RESULTS OF A PILOT STUDY OF DUST CONTROL TECHNOLOGY FOR ASPHALTMILLING

at

Payne amp Dolan IncUS Route 12 Project Wisconsin

With assistance fromThe National Asphalt Pavement Association Silica Parnership

REPORT WRITTEN BYAlan Echt MPH

Stanley Shulman PhDJay Colinet MS

Gerrit Goodman PhD

REPORT DATEOctober 25 2004

REPORT NOEPHB282-11 b

US DEPARTMENT OF HEALTH AN HUAN SERVICESCenters for Disease Control and Prevention

National mstitute for Occupational Safety and HealthDivision of Applied Research and Technology

Engineering and Physical Hazards Branch4676 Columbia Parkway Mail Stop R-5

Cincinnati Ohio 45226-1998

This Survey Report and any recommendations made herein are for the specific facility evaluated and may not be universally applicable Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual involved Additional NIOSH Survey Reports are available at httpwwwcdcgovnioshsurveyreports

SITES SURVEYED

sic CODE

SURVEY DATE

SURVEY CONDUCTED BY

EMPLOYER REPRESENTATIVE CONTACTED

Payne amp Dogravelan Inc Route 12 Maintenance Project Wisconsin

1611 (Highway and Street Constrction)

October 7-92003

Alan Echt NIOSH DART Staey Shulman NIOSH DART Jay Colinet NIOSR PRL Gerrit Goodman NIOSH PRL

Carl Thiesen Payne amp Dolan Inc

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DISCLAIMER

Mention of company names or products does not constitute endorsement by the Centers for Disease Control and Prevention

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ACKNOWLEDGMENT

The authors than the National Asphalt Pavement Association Silca Parership for their efforts on behalf of ths study and for their assistance in aranging this site visit

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ABSTRACT

A pilot study was performed to evaluate the effectiveness of water spray controls for a cold miling machine The objective of ths study was to quantify the exposure reduction that could be achieved through the use of higher flow water-spray nozzles durng pavement miling The effectiveness of the dust controls examned in ths study was evaluated by measurng the reduction in the respirable dust and resprrable quart exposures in personal and area samples collected durg a typical milling job Use ofthe higher flow nozzles resulted in reductions in respirable dust and respirable quar exposures but the differences were not statistically signficant Durng this study the higher flow nozzles were only installed on the cutter dr and the cutter drm extension

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INTRODUCTION

The National Institute for Occupational Safety and Health (NOSH) is located in the Centers for Disease Control and Prevention (CDe) par of the Deparent of Health and Human Services (DHHS) NIOSH was established in 1970 by the Occupational Safety and Health Act at the same time that the Occupational Safety and Health Adminstration

Labor (DOL) The OSH Act legislation mandated NIOSH to conduct research and education programs separate from the standard-setting and enforcement fuctions conducted by OSHA An important area of NIaSH research deals with methods for controllng occupational exposure to potential chemical and physical hazards

(OSHA) was established in the Deparent of

The Engineering and Physical Hazards Branch (EPHB) of the Division of Applied Research and Technology (DART) has been given the lead within NIOSH to study and develop engineering controls and assess their impact on reducing occupational ilness Since 1976 EPHB (and its predecessor the Engineering Control Technology Branch) has conducted a large number of studies to evaluate engineerig control technology based upon industr process or control technique The objective of each ofthese studies has

been to evaluate and document control techniques and to determine their effectiveness in reducing potential health hazards in an industr or for a specific process

The primary aim of this project is to determine if the engineering controls supplied with new miling machines and operated according to the manufactuers recommendations are adequate to control worker exposures to respirable dust and respirable crystallne silca (in the fonI of quarz) The long term goal of ths project is to reduce worker exposures to silica hy providing data to support the development of a set of practice guidelines for the equipment if the engineering controls are adequate or to develop a set

best

of recommendations to improve the performance of controls if they are not adequate

Many constrction tasks have been associated with overexposure to crystalline silca (Rappaport et al 2003) Among these tasks are tuck pointing concrete sawing concrete grding and abrasive blasting (NIOSH 2000 Thorpe et aL 1999 Akbar-Kanadeh andBrillhar 2002 Glindmeyer and Hamad 1988) Road miling has also been shown to result in overexposures to respirable crystallne silca (Linch 2002 Rappaport et aL 2003 NJ Dept of Health and Senior Services 2001) However all three of the road-miling studies are limited because they do not provide enough information about the operating parameters and engineering controls present on the miling machies to determine if the overexposures were due to a lack of effective controls or poor work practices This study wil attempt to fill that knowledge gap

A varety of machinery and work practices are employed in asphalt pavement recycling includng cold-planers heater planers cold-millers and heater-scarfiers (public Works 1995) Cold-millng which uses a toothed rotating dr to grind and remove the

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pavement to be recycled is primarily used to remove surface deterioration on both asphalt and Portland cement concrete road surfaces (public Works 1995) The millng machines used in cold miling are the fociis ofthis investigation

the US 12The cold miling work observed durng ths piacutelot study was par of

section ofreconstruction project from CTH KP to STH 19 west in Wisconsin This was a

old US 12 that was rehabiltated and wil be tranferred to the local township There was a 20 ft wide concrete pavement placed in the early 1900s Above that was a layer of

varying thickness about 0 inches to 10 inches Above that was varying asphaIgravet pavement thiclmess of about 8 to more than 12 inches which had crushed aggregate base course of

been placed at varous times in about the last 60 years The asphaltic pavement was rutted and cracked to varying degrees The portion of old US 12 from Simpson Road to the south where it meets the new US 12 was re-graded on new alignent this pavement removal was specified by a Common Excavation item The Common Excavation item specification enables the contractor to remove the pavement in any way they see fit In this case the contractor chose to mill the pavement because it was of value

removed and disposed of In the area from Simpson to the nort this section was not re-graded but the entigravere existing asphaltic pavement was removed under the item of Removing Asphaltic Surface This specifies the removal of only the asphaltic pavement Again the contractor chose

as a recycled product The existing concrete was also

and recycle it (Neuhauser 2004)to salvage this pavement

This study was faciltated by a partership in cooperation with the National Asphalt Pavement Assocation that includes millng machine manufacturers contractors employee

the millng machinerepresentatives NIOSH and other interested paries One of

study on a 2003 miacuteling machine model with the latest state-of-the-ar water spraying system produced by the manufacturer The mill is a half-lane miling machine rated at 560HP with a water spray system capable of l5gpm at 200psI This system was put into production in 2001 - before initial discussions on testing airborne dust concentration

manufacturers manufacturer A had initially arranged to perform the pilot

About one week before the pilot study was to be performed manufacturer A leared that the 2003 mil would not be available for the test Instead an older machine was substituted The replacement machine was a half-lane millng machine rated at 800 HP with an eight-foot cutter and an older model water system designed for i Ogpm at 50psi

Manufacturer A knew that the lower water flow at much lower pressure would result in higher airborne dust content hut Manufacturer A was stil confident that the dust suppression system even on the older model machines should still be very effective if properly maintained and operated Therefore Manufacturer A agreed to perform the test (even with the last minute changes) as a means of getting at least a good baseline for this type of airborne dust test

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OCCUPATIONAL EXPOSUR TO CRYSTALLIN SILICA

Silcosis is an occupational respiratory disease caused by inaling respirable crystalline

silca dust Silcosis is irreversible often progressive (even after exposure has ceased)

and potentially fataL Because no effective treatment exists for silicosis prevention though exposure control is essentiaL Exposure to respirable crystalline silca dust occurs in many occupations including constrction Crystalline silca refers to a group of minerals composed of silcon and oxygen a crystalline strctue is one in which the atoms are aranged in a repeating three-dimensional pattern (Bureau of Mines 1992) The three major forms of crystalline silca are quartz cristobalite and trdymite quar is the most common form (Bureau of Mines 1992) Respirable refers to that portion of airborne crystalline silca that is capable of entering the gas-exchange regions of the lungs if inhaled this includes paricles with aerodynamc diameters less than approximately 10

Ilm (NOSH 2002)

When proper practices are not followed or controls are not maintained respirable crystallne silica exposures can exceed the NIaSH Recommended Exposure Limit

Permssible Exposure Limit (PEL) or the American Conference of(RL) the OSHA

Governental Industral Hygienists (ACGIH) Threshold Limit Value (TLV) (NOSH 200229 CFR 19101000 ACGll 2004) NiaSH recommends an exposure limit of 005 mgm3 to reduce the risk of developing silicosis lung cancer and other adverse health effects

The OSHA PEL for respirable dust containing 1 quarz or more in general industr is expressed as an equation (29 CFR 19101000)

10 mgm3 Respirable PEL =

Silca + 2

If for example the dust contai no crystalline silica the PEL is 5 mgm3 and if the dust is 100 crystalline silca the PEL is 01 mgm3 For trdymite and cristobalite OSHA uses half the value calculated using the formula for quarz (29 CPR 19101000)

The curent OSHA permissible exposure limit (PEL) for respirable dust containng crystallne silica (quartz) for the constrction industr is measured by impinger sampling The PEL is expressed in millons of paricles per cubic foot (mppcf) and is calculated using the following formula (29 CFR 192655)

250 mppcf Respirable PEL =

Silca + 5

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Since the PELs were adopted the impinger sampling method ha been rendered obsolete by gravimetrc sampling (OSHA 1996) OSHA is not aware of any goverent agencies or employers in ths countr that are curently usng impinger sampling to assess worker

exposure to dust containig crystallne silca and impinger samples are generally

recogned as being less reliable than gravimetrc samples (OSHA 1996) OSHA has determed that sampling procedures in the consction industr should be the same as in general industr and that the mppcfPEL in 29 CFR 192655(a) is equivalent to the mgm3 PEL in 29 CFR 19101000 (aSHA 1996)

The ACGrnCE TL VIs for cristobalte quar and trdymte are all 005 mglm3 (ACGm 2004) The ACGrn~ ha published a notice of their intent to change the TL ~ for (Xshyquar and cristobalte (respirable fraction) to 0025 mgm3 and to withdraw the documentation and adopted TL yi for trdymte (ACGrn 2004)

METHODS

Descriptive data about the millig machie were gathered durng the aferoon and evening prior to the fist day of sampling while the machie was undergoing repais at the Payne amp Dolan shop Information was collected about the number tye condition and placement of water spray nozzles on thedr and at the conveyor belt tranitions the cutter dr rotation rate (measured using a non-contact tachometer (T AC2K Dwyer Instrents Inc Michigan City Indiana) while the mill was rug) the hours on the machie the cutter dr condition and the cutter bits including their spacing condition make and model number NIOSH personnel worked with Payne amp Dolan sta and the manufactuers representative to install water flow meters and pressure gauges install new water spray nozzles and cutter bits and restore the water spray nozzles at the seconda conveyor tranition to the manufactuers specification This tie was also used to lear aboutthe operation of the machie and safe work practices

Water flow rate was measured using two water flow meters (Confowmeter II Confow Inc WashigtonP A) intaled in the water supply lies on the milL One meter was installed in the line between the water pump and the cutter dr spray bar The second meter was installed in the line between the water pump and the conveyor transition sprays (Figure 1 ) Water pressure was measured using pressure gauges attched to tee-fittgs

instaled in the water lie supplyig the cutter dr spray bar (Figue 2) in the water line

supplyigthe spray bar for the fist conveyor belt tranition and in the water lie supplyig the nozzles on the secondar conveyor transition The readings on thesemeters and gauges were obsered and recorded periodicaly thoughout both days of millig

Vehic1e speed and diection of trvel was meased using a Trible GeoXT hadheld data-loggig global positionig system (GPS) unt (Trible Navigation Ltd Sunyvale CA) receiver on the second day of millig The GPS unt was placed on padding on the top of the millig machie in an empty fi-extiguisher bracket (the extingusher had been relocated previously) in front of the operators station (Figue 3) Speed was also

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observing and recording the foot speed reading on the intrent panel ofthe mil every two minutes As a measure recorded durng both days of miling by a NIOSH researcher

of productivity the time was recorded when each dump truck was loaded and pulled away from the millng machine

Depth of cut was measurecl every fifteen minutes during both milling days using a tape measure helcl at the edge of the cut pavement The width of the cut was measured as well Bulk samples of the miled pavement were collected on a periodic basis from

left in or next to the cut by the milling machine Wind speed and direction and temperature were recorded usigraveng a data-loggigraveug weather station (MultiLog Weather material

Station Fourier Systems Inc Atlanta GA) A hand-held muitigrave~directional impeller wind meter was also used during the survey (Skywatch Meteos JDC Electronic SA Yverdon-Ies-Bains Switzerland)

The work practices and use of personal protective equipment were recorded for each worker sampled including the workers position and distance relative to the miling machine (eg walking alongside following behind riding) Infomiation obtained from conversations with worlcers to detennine if the sampling days were typical of the nomial work load helped to place the sampling results in proper perspective Data were recorded describing other operations nearby that generated dust including the process its location relatIacuteve to the miling machine and whether it was upwind or downwind of the millng machine

Dust and Silca Sampling Methods

On both days of sampling personal breathing zone samples on the three members of the miling crew were collected at a flow rate of 42 liters per minute (Umin) using a battery-operated sampling pump at the employees waist connected via flexible tubing to a pre-weighed 37-mm diameter 5-micron (~m) pore-size polyvinyl chloride filter supported by a backup pad in a three-piece filter cassette sealed with a cellulose shrink band in accordance with NIOSH Methods 0600 and 7500 and a cyclone (GK 269 RespirableThoracic Cyclone BGi Inc Waltham MA) placed in the employees breathing zone (NIOSH 1994 HSE 1997)

Area samples were collected on both days of sampling at six locations on the millng instruments mounted on a metal frame (Figure 4) Themachine using an aray of

platform near the level controls onlocations included the dashboard on the operators

both sides of the mil near the cutter dr on both sides of the mil and on the right side

conveyor to the loading conveyor (Figure 5) The sampling intruments in each aray included a Ii ght-scattering aerosol photometer (pDR near the transition from the primary

Theano Electron Corp Franklin MA) with a 10 millmeter (mm) nylon cyclone comiected to the inlet via flexible tubing The pDR was in tur connected via flexible tubing to a battery-operated sampling pump calibrated at a flow rate of 17 Llmin A pre-weighed 5-~m pore-size polyvinyl chloride filter supported by a backup pad in a two-piece filter cassette sealed with a cellulose shr band was placed in line between the

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pDR and the pump Also included in each sampling aray were two battery-operated sampling pumps both connected though flexible tubing to a 10-mm nylon cyclone and a pre-weighed 37-mm diameter 5-iexclm pore-size polyvnyl chloride filter supported by a backup pad in a two-piece filter cassette sealed with a cellulose shn band in accordance with NIOSH Methods 0600 and 7500

On the second day of sampling addigravetional area sauiples were collected at the six locations described above at a flow rate of 42 litersminute using a battery-operated sampling pump connected via flexible tubing to a pre-weighed 37-mm diameter 5shymicron (iexclm) pore-size polyvinyl chloride filter supported by a backup pad in a three-piece fiter cassette sealed with a cellulose shrink band in accordance with NIOSH Methods 0600 and 7500 and a cyclone (OK 269 RespirableThoracic Cyclone BGI Inc Waltham MA) attached to the metal frame

Gravimetric analysis for respirable pariculate was cared out with the fOllOWing modifications to NIOSH Method 0600 1) the fiters and backup pads were stored in an environmentally controlled room (201 1degC and 50i5 relative humidity) and were subj ected to the room conditions for at least two hours for stabilization prior to tare and gross weighing and 2) two weighings of the tare weight and gross weight were performed (NIOSH 1994) The difference between the average gross weight and the average tare weight was the result of the analysis The limit of detection for this method was 002 mg

Crystalline silica analysis ofthehigravegher-flow fiter and all bulk samples was perfornied using X-ray diffraction NIOSHMethod 7500 was used ith the following modifications 1) fiters were dissolved in tetraIgraveydrofurail rather than being ashed in a furace and 2) standards and samples were run concurently and an external calibration ciire was prepared from the integrated intensities rather than using the suggested normalization procedure (NIOSH 1994) These samples were analyzed for quarz and cristobalite The limits of detection for quarz and cristobalite on filters were 001 and 002 mg respectively The limit of quantiation is 003 mg for both quarz and cristobalite The lower-flow filter samples were not analyzed for silica

bulk samples collected from miled pavement left in or next to the cut by the millng machine The limit of detection for quar in bulk samples was 08 The limit of quantitation was 2

The silica content of the pavement was determined though testing of

Experimental design

Initial activities on site such as installing new water spray nozzles and new cutter-drm teeth were devoted to returing the mil to the manufacturers specifications DulIgraveng the

first day of sampling samples were collected over thee sampliacuteng periods during a typical miling job The second day of sampling was divided into four 2-hour periods During

the first period the manufacturer-specified nozzles (UniJetll model1 005 SS Spraying Systems Co Wheaton IL) rated at 05 gallons per minute (gpm) at 40 pounds per square

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inch (psi) were used For the second and thd period higher-flow nozzles CUniJ etQI

model 11008 Spraying System Co Wheaton IL) rated at 08 gpm at 40 psi were installed on the cutter-dr spray bar Durng the final period the manufactuershy

specified nozzles were used again This design was used instead of a randomized design because of the length of time and effort required to change the nozzles in the field The spray nozzles for the primar conveyor and the material transfer conveyor were not changed Personal and high-flow area samples for respirable dust and respirable crystallne silica were changed approximately every two hours durig both sampling days The lower-flow area samples were collected for the full shift on both days

RESULTS AND DISCUSSION

Description of the Mil and the Controls

The miling machine used at this site had 3560 hours on the machine at the beginnng of the site visit It was equipped with water spray nozzles at three places including dr spraying nozzles primar conveyor spraying nozzles and material transfer conveying nozzles There were 18 flat fan spray nozzles (UniJetQI model 11005 SS Spraying Systems Co Wheaton IL) mounted on a spragravey bar in the cutter dru housing This type

of nozzle was used at all of the installations on this milL Thegrave fist thee nozzles on the cutter dr spray bar were mounted 2 inches (in) apar the thrd and fourh nozzle were

mounted 3 in apar and the remaining nozzles were 5 Yi in apar The cutter dr

extension was served by a separate spray bar equipped with thee nozzles The first two nozzles were 2in apar while the second and thrd nozzle were 5 Yi in apar There were a total of nine nozzles at the primary conveyor installed at the transition from the cutter dr to the primar conveyor four were mounted on each side and one on the extension

These nozzles were 1 foot apar There were two nozzles mounted above the material transfer conveyor at the transition from the primar cogravenveyor Those nozzles were 32 in apar New nozzles were installed on the evening before the first sampling day The water pump for the spraying system is rated at 40 Llmin (106 gallons) of water at 3 Yi bar (51 psi)

The 8 ft 6 in wide cutter dr held 193 bits aranged in a helical coil around the dr

holders were in factory spec condition with 50 hrs on the holders NewThe drm and

bits were installed on the evening before the first sampling day and were changed several times durg the next two days The dr rotation was measured and found to agree with

the manufacturers specification of928 rpm

Personal protective equipment and work practices

The miling crew members wore hard hats (except the operator) safety glasses and traffc safety vests The operator was the only employee who spent all of his time on the mil operating the mil from either the right or left side of the operators station The foreman spent the majority of the first day operatig the rear controls while the thid ecircrewman performed tasks such as operating a skid-steer loader and drvig the water

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in the afternoon the foreman operated the skid steer loader while the third crewman ran the rear controls For the most par the skid-steer loader was not operated near the miling machine on the first day On one occasion a road grader passed by and for a brief period in the afternoon nugravellig took place alongside a field while a farer was running a combine On the second day the skid-steer loader

truck (Figure 6) However

the daythe day and the third crew member spent most ofwas idle for the majority of

the rear controls The foreman left the migravelperiodically to attend torunning one of

matters such as trck scheduling On both days the trcks assigned to take away thepossiblethe road unti that was no longermiled material drove on the paved portion of

lessening the potential of dust being generated by the trucks as they passed the millng machine

Respirable dust and crystallne silica sampling results

personal breathing zone sampling for respirable dust and crystalline silica conducted on October 8 are presented in Table 1 On October 8 which represented a typical millng day respirable dust results ranged from 014 to 183 mgm The TW A respirable dust exposures for the three employees were 026 mgmJ (499 minutes) for the

The results of

operator 10 mgm3 (495 minutes) for the foreman and 038 mgm3 (438 minutes) for the third employee who began the day operatin~ the skid steer loader Their 8-hour TWAs were 027 mgm3 for the operator 10 mgm for the foreman and 035 mgm3 for the third crew member The OSHA PELs for these employees calculated based upon the percent silica in their samples were 142 mgm 3 for the operator 117 mgm3 for the foreman and 113 mgm3 for the third member of the miling crew The PELs were calculated using the value of the LODJ for quarz values below the LOD (Hornung and Reed 1990) None of the employees exposures exceeded the OSHA PEL on October 8 as a TW A but excursions above the PEL did take place during the first two sampling periods for the foreman who spent most of those periods operating the rear controls on the mUL

Respirable quarz results from personal samples ranged from below the limit of to

detection 01 1 inglm3 The TW A respirable quarz exposures for October 8 were 0013 mgm3 for the operator 0064 mgm3 for the foreman and 0030 mgm3 for the third

LOD formiling Crew member The TWAs were also calculated using the value of

001 mg Their 8-hour quartz TWAs were 0014 mgm3 0066 mglm3 and 0027 mgm3 respectively On October 8 the foremans TWA and 8-hour TWA exposure exceeded the NIOSH quarz REL of 005 nigm3

quarz results less than the LOD of

the milling crews respirable dust and respirable quartzTable 2 lists the results of

exposures by nozzle type and employee results in TWAs of21 mgm3 for the operator 062 mgm3 for the foreman and 11 mgm3 for the rear control operator for the UniJ etfI 11005 nozzle versus 14 mglm3 065 mgm3 and 089 mgm respectively forthe UniJetaeligl 11008 nozzle TWA

samples on October 9 Calculating TWA respirable dust

the operator 0041

mgm3 for the foreman and 0050 mgin3 for the worker operating the rear controls quartz results for the UniJetfI 11005 nozzle were 012 mgm3 for

8

0081 mgm3 for the operator TW A quarz results for the UniacuteJetlIII008 nozzle were

0041 mgm3 for the foreman and 0043 mgm3 for the thrd crewman In contrast to October 8 the operator received the highest exposures on the second sampling day

Table 3 shows that the highest emissionsthe nozzle type Inspection ofregardless of

side of the mil and the upper conveyor Unfortunately the weather station did not log data so the effect of the wind direction on those results is unnown

were associated with the left

the area samplescoUected on October 8 with the lower-flow respirable dust samplers (17 Lmin) and the pdR direct-reading instruments Those results indicate that for both sampling methods that exposures were lowest igraven the

Table 4 reports the results of

operators station and highest at the upper conveyor (the material transfer conveyor) This table also lists the gravimetricpDR ratios calculated for each sampling location These ratios were used to adjust pDR short teimsampling concentrations which are provided later in ths report Table 5 presents the results for the lower-flow respirable

dust samples and the pdR samples for October 9 including the results from all nozzle types The upper conveyor produced the highest exposure on that day as welL Perhaps the operators personal exposures differ from the area sample at his work station because

the time on one or the other side of the mm while the sampler was in the

he spends most of

his work station (Figure 7) Table 5 which provides the results ofthe center of

lower-flow andpdR area samples shows that as in Table 3 the highest emissions were associated with the left side of the mill and the upper conveyor The migraveU removed

the road so the left side oftlie mm was facing the pavedmaterial from the right side of

the road while the right side faced the previous cut This orientation may explain the milL The manufacturers

edge of

in par why the exposures were higher on the left side of

6 relates area samplingrepresentative attributed this result to passing truck trame Table

results to productivity water flow and water spray pressure while Table 7 describes the work done on October 9

When reviewing the results of sampling conducted on October 9 for the purpose of this study it is useful to compare the results obtained when the different water spray nozzles

logwere used For the purpose ofthisaualysis the results were converted to the natural

the data did not vary with(In) scale because on the log scale the varabmty of

concentration From the In scale analysis of the respirable dust results (Tables 8~ II) the ratio of the UniJ etlf 11005 nozzle to the DniJ et(szlig i 1008 nozzle results is the ratio of their geometric means 12 This indicates that the respirable dust measurements obtained

are about 20 higher thotigh the result is not statistically significant even at the lO signifcance leveL Results for the pDRs are while the UniJetlf 11005 nozzle was used

also about 20 higher for the UnijetQ 11005 and are also notsimilar Those results are

statistically significant at the 10 leveL Examination oftbe tables indicates that for mostthe

groupings the UniJetlIl1005 nozzle does give higher results Review of all of

the UniacuteJet(( 11005 nozzle resultsrespirable dust data from October 9 shows that 59 of

exceeded the PEL while 50 of the UniJetI 11008 nozzle results did so For personal breathing zone samples half of the results while the Unijet(szlig 11005 was in use exceeded

the UnijetlI 11008 results exceeded the PELthe PEL one third of

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From the In scale analysis of the quarz samplig results (Tables 12-15) the ratio of the Uniet(szlig 11005 nozzle to the Uniet(szlig 11008 nozzle results is the ratio of their geometrc means 116 Thus for respirable quar the results while Uniet(szlig i 1005 nozzles were intalled on the cutter drm were about 16 higher though the result is not statisticaly signficant even at the 10 signcance leveL Examation of the tables indicates that the quar results are not as consistent as those for respirable dust For data from both days 7 respirable quar results were less than the LOD and 13 values were between LOD and LOQ For the seven quarz values below the LOD the value Lan was substituted

Quarz in bulk samples

The results of 10 bulk samples ranged from 12 to 28 with a mean of 199 and a median of 185

CONCLUSIONS AN RECOMMNDATIONS

Conclusions from ths pilot study regardig the effect of increasing the water flow to the spray nozzles on dust and quart exposures are lited by several factors First the higher flow nozzles were only intalled on the cutter dr and the cutter dr extension

the nozzles selected represent a difference of only 30 more flow when the higher-flow nozzles were installed Nevereless the respirable dust measurements obtaied while the Uniet(szlig 11005 nozzles were used were about 20 higher than when the higher-flow Uniet(szlig 11008 nozzles were used The respirable quarz results while Uniet(szlig 11005 nozzles were installed on the cutter dr were about 16 higher Neither

Second

the reductions in respirable dust concentrations nor those for the quarz results were statistically signficant even at the lO signficance leveL Statistical signficance mean that the difference is not due to chance alone

Research on dust controls in minig has shown that water sprays have two roles wetting of broken material being transported and airborne captue (NOSH 2003) Uniformly wetting the broken material durg the breakage process is far more effective and enures that dust paricles stay attached to the materal (NQSH 2003) Increasing the water flow rate and increasing the number of sprays have both been shown to be effective it is tooearly in this proj ect to recommend an approach In one inance dust from a shearer dr was reduced by 60 when the 46 smaler orifice nozzles were substituted for the originall7 nozzles with the pressure and flow held constant (NOSH 2003) The shape of the spray is another importnt factor in its effectveness

Futue studies might test the water system on a newer-model machie to begi to explore the relationship between water flow and pressue agravend aiborne dust concentrtions Varables related to the site andjob might obscure ths relationship but it is hoped that a trend might emerge

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REFERENCES

29 CFR 19101000 (2001) Occupational Safety and Health Admstration air

containants

29 CFR 192655 (2003) Occupational Safety and Health Adminstration gases vapors fues dusts and mists

ACGrn (2004) Theshold limit values for chemical substances CincinatiOH American Conference of Governental Industral Hygienists

Akbar-Khanadeh F Brillhar RL (2002) Respirable crystallne silca dust exposure durng concrete finshing (grnding) using hand-held grnders in the constrction industr An occup Hyg 46341-346

Bureau of Mines (1992) Crystallne silica primer Washigton DC US Deparent of the Interior Bureau of Mines Branch of Industral Minerals Special Publication

Glindmeyer HW Hamad YY (1988) Contributing factors to sandblasters silcosis inadequate respiratory protection equipment and standards J accup Med 30917-921

HSE (1997) MDHS 142 General methods for sampling and gravimetrc analysis of respirable and total inhalable dust Methods for the determination of hazardous substances lIealth and safety laboratory Sudbur Suffolk UK Health and Safety Executive

Homuug R Reed L (1990) Estimation of average concentration in the presence of nondetectable values Applied Occupational and Environmental Hygiene 5(1)46-51

Linch KD (2002) Respirable concrete dust-silcosis hazard in the constrction industr

Appl Occup and Environ Hyg 17 209-221

Neuhauser Curt (curneuhauser(ecircdotstatewius) (2004) RE US 12 project Private e-mail message to Alan Echt (AEcht(ecirccdcgov) Januar 7

New Jersey Deparent of Health and Senior Services (2001) New Jersey silica parership In Occupational Health Sureilance Update February Trenton NJ NJ

Deparment of Health and Senior Services Division of Epidemiology Environmental and Occupational Health Occupational Health Service Occupational Health Sureilance Program

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DISCLAIMER

Mention of company names or products does not constitute endorsement by the Centers for Disease Control and Prevention

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ACKNOWLEDGMENT

The authors than the National Asphalt Pavement Association Silca Parership for their efforts on behalf of ths study and for their assistance in aranging this site visit

iv

ABSTRACT

A pilot study was performed to evaluate the effectiveness of water spray controls for a cold miling machine The objective of ths study was to quantify the exposure reduction that could be achieved through the use of higher flow water-spray nozzles durng pavement miling The effectiveness of the dust controls examned in ths study was evaluated by measurng the reduction in the respirable dust and resprrable quart exposures in personal and area samples collected durg a typical milling job Use ofthe higher flow nozzles resulted in reductions in respirable dust and respirable quar exposures but the differences were not statistically signficant Durng this study the higher flow nozzles were only installed on the cutter dr and the cutter drm extension

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INTRODUCTION

The National Institute for Occupational Safety and Health (NOSH) is located in the Centers for Disease Control and Prevention (CDe) par of the Deparent of Health and Human Services (DHHS) NIOSH was established in 1970 by the Occupational Safety and Health Act at the same time that the Occupational Safety and Health Adminstration

Labor (DOL) The OSH Act legislation mandated NIOSH to conduct research and education programs separate from the standard-setting and enforcement fuctions conducted by OSHA An important area of NIaSH research deals with methods for controllng occupational exposure to potential chemical and physical hazards

(OSHA) was established in the Deparent of

The Engineering and Physical Hazards Branch (EPHB) of the Division of Applied Research and Technology (DART) has been given the lead within NIOSH to study and develop engineering controls and assess their impact on reducing occupational ilness Since 1976 EPHB (and its predecessor the Engineering Control Technology Branch) has conducted a large number of studies to evaluate engineerig control technology based upon industr process or control technique The objective of each ofthese studies has

been to evaluate and document control techniques and to determine their effectiveness in reducing potential health hazards in an industr or for a specific process

The primary aim of this project is to determine if the engineering controls supplied with new miling machines and operated according to the manufactuers recommendations are adequate to control worker exposures to respirable dust and respirable crystallne silca (in the fonI of quarz) The long term goal of ths project is to reduce worker exposures to silica hy providing data to support the development of a set of practice guidelines for the equipment if the engineering controls are adequate or to develop a set

best

of recommendations to improve the performance of controls if they are not adequate

Many constrction tasks have been associated with overexposure to crystalline silca (Rappaport et al 2003) Among these tasks are tuck pointing concrete sawing concrete grding and abrasive blasting (NIOSH 2000 Thorpe et aL 1999 Akbar-Kanadeh andBrillhar 2002 Glindmeyer and Hamad 1988) Road miling has also been shown to result in overexposures to respirable crystallne silca (Linch 2002 Rappaport et aL 2003 NJ Dept of Health and Senior Services 2001) However all three of the road-miling studies are limited because they do not provide enough information about the operating parameters and engineering controls present on the miling machies to determine if the overexposures were due to a lack of effective controls or poor work practices This study wil attempt to fill that knowledge gap

A varety of machinery and work practices are employed in asphalt pavement recycling includng cold-planers heater planers cold-millers and heater-scarfiers (public Works 1995) Cold-millng which uses a toothed rotating dr to grind and remove the

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pavement to be recycled is primarily used to remove surface deterioration on both asphalt and Portland cement concrete road surfaces (public Works 1995) The millng machines used in cold miling are the fociis ofthis investigation

the US 12The cold miling work observed durng ths piacutelot study was par of

section ofreconstruction project from CTH KP to STH 19 west in Wisconsin This was a

old US 12 that was rehabiltated and wil be tranferred to the local township There was a 20 ft wide concrete pavement placed in the early 1900s Above that was a layer of

varying thickness about 0 inches to 10 inches Above that was varying asphaIgravet pavement thiclmess of about 8 to more than 12 inches which had crushed aggregate base course of

been placed at varous times in about the last 60 years The asphaltic pavement was rutted and cracked to varying degrees The portion of old US 12 from Simpson Road to the south where it meets the new US 12 was re-graded on new alignent this pavement removal was specified by a Common Excavation item The Common Excavation item specification enables the contractor to remove the pavement in any way they see fit In this case the contractor chose to mill the pavement because it was of value

removed and disposed of In the area from Simpson to the nort this section was not re-graded but the entigravere existing asphaltic pavement was removed under the item of Removing Asphaltic Surface This specifies the removal of only the asphaltic pavement Again the contractor chose

as a recycled product The existing concrete was also

and recycle it (Neuhauser 2004)to salvage this pavement

This study was faciltated by a partership in cooperation with the National Asphalt Pavement Assocation that includes millng machine manufacturers contractors employee

the millng machinerepresentatives NIOSH and other interested paries One of

study on a 2003 miacuteling machine model with the latest state-of-the-ar water spraying system produced by the manufacturer The mill is a half-lane miling machine rated at 560HP with a water spray system capable of l5gpm at 200psI This system was put into production in 2001 - before initial discussions on testing airborne dust concentration

manufacturers manufacturer A had initially arranged to perform the pilot

About one week before the pilot study was to be performed manufacturer A leared that the 2003 mil would not be available for the test Instead an older machine was substituted The replacement machine was a half-lane millng machine rated at 800 HP with an eight-foot cutter and an older model water system designed for i Ogpm at 50psi

Manufacturer A knew that the lower water flow at much lower pressure would result in higher airborne dust content hut Manufacturer A was stil confident that the dust suppression system even on the older model machines should still be very effective if properly maintained and operated Therefore Manufacturer A agreed to perform the test (even with the last minute changes) as a means of getting at least a good baseline for this type of airborne dust test

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OCCUPATIONAL EXPOSUR TO CRYSTALLIN SILICA

Silcosis is an occupational respiratory disease caused by inaling respirable crystalline

silca dust Silcosis is irreversible often progressive (even after exposure has ceased)

and potentially fataL Because no effective treatment exists for silicosis prevention though exposure control is essentiaL Exposure to respirable crystalline silca dust occurs in many occupations including constrction Crystalline silca refers to a group of minerals composed of silcon and oxygen a crystalline strctue is one in which the atoms are aranged in a repeating three-dimensional pattern (Bureau of Mines 1992) The three major forms of crystalline silca are quartz cristobalite and trdymite quar is the most common form (Bureau of Mines 1992) Respirable refers to that portion of airborne crystalline silca that is capable of entering the gas-exchange regions of the lungs if inhaled this includes paricles with aerodynamc diameters less than approximately 10

Ilm (NOSH 2002)

When proper practices are not followed or controls are not maintained respirable crystallne silica exposures can exceed the NIaSH Recommended Exposure Limit

Permssible Exposure Limit (PEL) or the American Conference of(RL) the OSHA

Governental Industral Hygienists (ACGIH) Threshold Limit Value (TLV) (NOSH 200229 CFR 19101000 ACGll 2004) NiaSH recommends an exposure limit of 005 mgm3 to reduce the risk of developing silicosis lung cancer and other adverse health effects

The OSHA PEL for respirable dust containing 1 quarz or more in general industr is expressed as an equation (29 CFR 19101000)

10 mgm3 Respirable PEL =

Silca + 2

If for example the dust contai no crystalline silica the PEL is 5 mgm3 and if the dust is 100 crystalline silca the PEL is 01 mgm3 For trdymite and cristobalite OSHA uses half the value calculated using the formula for quarz (29 CPR 19101000)

The curent OSHA permissible exposure limit (PEL) for respirable dust containng crystallne silica (quartz) for the constrction industr is measured by impinger sampling The PEL is expressed in millons of paricles per cubic foot (mppcf) and is calculated using the following formula (29 CFR 192655)

250 mppcf Respirable PEL =

Silca + 5

3

Since the PELs were adopted the impinger sampling method ha been rendered obsolete by gravimetrc sampling (OSHA 1996) OSHA is not aware of any goverent agencies or employers in ths countr that are curently usng impinger sampling to assess worker

exposure to dust containig crystallne silca and impinger samples are generally

recogned as being less reliable than gravimetrc samples (OSHA 1996) OSHA has determed that sampling procedures in the consction industr should be the same as in general industr and that the mppcfPEL in 29 CFR 192655(a) is equivalent to the mgm3 PEL in 29 CFR 19101000 (aSHA 1996)

The ACGrnCE TL VIs for cristobalte quar and trdymte are all 005 mglm3 (ACGm 2004) The ACGrn~ ha published a notice of their intent to change the TL ~ for (Xshyquar and cristobalte (respirable fraction) to 0025 mgm3 and to withdraw the documentation and adopted TL yi for trdymte (ACGrn 2004)

METHODS

Descriptive data about the millig machie were gathered durng the aferoon and evening prior to the fist day of sampling while the machie was undergoing repais at the Payne amp Dolan shop Information was collected about the number tye condition and placement of water spray nozzles on thedr and at the conveyor belt tranitions the cutter dr rotation rate (measured using a non-contact tachometer (T AC2K Dwyer Instrents Inc Michigan City Indiana) while the mill was rug) the hours on the machie the cutter dr condition and the cutter bits including their spacing condition make and model number NIOSH personnel worked with Payne amp Dolan sta and the manufactuers representative to install water flow meters and pressure gauges install new water spray nozzles and cutter bits and restore the water spray nozzles at the seconda conveyor tranition to the manufactuers specification This tie was also used to lear aboutthe operation of the machie and safe work practices

Water flow rate was measured using two water flow meters (Confowmeter II Confow Inc WashigtonP A) intaled in the water supply lies on the milL One meter was installed in the line between the water pump and the cutter dr spray bar The second meter was installed in the line between the water pump and the conveyor transition sprays (Figure 1 ) Water pressure was measured using pressure gauges attched to tee-fittgs

instaled in the water lie supplyig the cutter dr spray bar (Figue 2) in the water line

supplyigthe spray bar for the fist conveyor belt tranition and in the water lie supplyig the nozzles on the secondar conveyor transition The readings on thesemeters and gauges were obsered and recorded periodicaly thoughout both days of millig

Vehic1e speed and diection of trvel was meased using a Trible GeoXT hadheld data-loggig global positionig system (GPS) unt (Trible Navigation Ltd Sunyvale CA) receiver on the second day of millig The GPS unt was placed on padding on the top of the millig machie in an empty fi-extiguisher bracket (the extingusher had been relocated previously) in front of the operators station (Figue 3) Speed was also

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observing and recording the foot speed reading on the intrent panel ofthe mil every two minutes As a measure recorded durng both days of miling by a NIOSH researcher

of productivity the time was recorded when each dump truck was loaded and pulled away from the millng machine

Depth of cut was measurecl every fifteen minutes during both milling days using a tape measure helcl at the edge of the cut pavement The width of the cut was measured as well Bulk samples of the miled pavement were collected on a periodic basis from

left in or next to the cut by the milling machine Wind speed and direction and temperature were recorded usigraveng a data-loggigraveug weather station (MultiLog Weather material

Station Fourier Systems Inc Atlanta GA) A hand-held muitigrave~directional impeller wind meter was also used during the survey (Skywatch Meteos JDC Electronic SA Yverdon-Ies-Bains Switzerland)

The work practices and use of personal protective equipment were recorded for each worker sampled including the workers position and distance relative to the miling machine (eg walking alongside following behind riding) Infomiation obtained from conversations with worlcers to detennine if the sampling days were typical of the nomial work load helped to place the sampling results in proper perspective Data were recorded describing other operations nearby that generated dust including the process its location relatIacuteve to the miling machine and whether it was upwind or downwind of the millng machine

Dust and Silca Sampling Methods

On both days of sampling personal breathing zone samples on the three members of the miling crew were collected at a flow rate of 42 liters per minute (Umin) using a battery-operated sampling pump at the employees waist connected via flexible tubing to a pre-weighed 37-mm diameter 5-micron (~m) pore-size polyvinyl chloride filter supported by a backup pad in a three-piece filter cassette sealed with a cellulose shrink band in accordance with NIOSH Methods 0600 and 7500 and a cyclone (GK 269 RespirableThoracic Cyclone BGi Inc Waltham MA) placed in the employees breathing zone (NIOSH 1994 HSE 1997)

Area samples were collected on both days of sampling at six locations on the millng instruments mounted on a metal frame (Figure 4) Themachine using an aray of

platform near the level controls onlocations included the dashboard on the operators

both sides of the mil near the cutter dr on both sides of the mil and on the right side

conveyor to the loading conveyor (Figure 5) The sampling intruments in each aray included a Ii ght-scattering aerosol photometer (pDR near the transition from the primary

Theano Electron Corp Franklin MA) with a 10 millmeter (mm) nylon cyclone comiected to the inlet via flexible tubing The pDR was in tur connected via flexible tubing to a battery-operated sampling pump calibrated at a flow rate of 17 Llmin A pre-weighed 5-~m pore-size polyvinyl chloride filter supported by a backup pad in a two-piece filter cassette sealed with a cellulose shr band was placed in line between the

5

pDR and the pump Also included in each sampling aray were two battery-operated sampling pumps both connected though flexible tubing to a 10-mm nylon cyclone and a pre-weighed 37-mm diameter 5-iexclm pore-size polyvnyl chloride filter supported by a backup pad in a two-piece filter cassette sealed with a cellulose shn band in accordance with NIOSH Methods 0600 and 7500

On the second day of sampling addigravetional area sauiples were collected at the six locations described above at a flow rate of 42 litersminute using a battery-operated sampling pump connected via flexible tubing to a pre-weighed 37-mm diameter 5shymicron (iexclm) pore-size polyvinyl chloride filter supported by a backup pad in a three-piece fiter cassette sealed with a cellulose shrink band in accordance with NIOSH Methods 0600 and 7500 and a cyclone (OK 269 RespirableThoracic Cyclone BGI Inc Waltham MA) attached to the metal frame

Gravimetric analysis for respirable pariculate was cared out with the fOllOWing modifications to NIOSH Method 0600 1) the fiters and backup pads were stored in an environmentally controlled room (201 1degC and 50i5 relative humidity) and were subj ected to the room conditions for at least two hours for stabilization prior to tare and gross weighing and 2) two weighings of the tare weight and gross weight were performed (NIOSH 1994) The difference between the average gross weight and the average tare weight was the result of the analysis The limit of detection for this method was 002 mg

Crystalline silica analysis ofthehigravegher-flow fiter and all bulk samples was perfornied using X-ray diffraction NIOSHMethod 7500 was used ith the following modifications 1) fiters were dissolved in tetraIgraveydrofurail rather than being ashed in a furace and 2) standards and samples were run concurently and an external calibration ciire was prepared from the integrated intensities rather than using the suggested normalization procedure (NIOSH 1994) These samples were analyzed for quarz and cristobalite The limits of detection for quarz and cristobalite on filters were 001 and 002 mg respectively The limit of quantiation is 003 mg for both quarz and cristobalite The lower-flow filter samples were not analyzed for silica

bulk samples collected from miled pavement left in or next to the cut by the millng machine The limit of detection for quar in bulk samples was 08 The limit of quantitation was 2

The silica content of the pavement was determined though testing of

Experimental design

Initial activities on site such as installing new water spray nozzles and new cutter-drm teeth were devoted to returing the mil to the manufacturers specifications DulIgraveng the

first day of sampling samples were collected over thee sampliacuteng periods during a typical miling job The second day of sampling was divided into four 2-hour periods During

the first period the manufacturer-specified nozzles (UniJetll model1 005 SS Spraying Systems Co Wheaton IL) rated at 05 gallons per minute (gpm) at 40 pounds per square

6

inch (psi) were used For the second and thd period higher-flow nozzles CUniJ etQI

model 11008 Spraying System Co Wheaton IL) rated at 08 gpm at 40 psi were installed on the cutter-dr spray bar Durng the final period the manufactuershy

specified nozzles were used again This design was used instead of a randomized design because of the length of time and effort required to change the nozzles in the field The spray nozzles for the primar conveyor and the material transfer conveyor were not changed Personal and high-flow area samples for respirable dust and respirable crystallne silica were changed approximately every two hours durig both sampling days The lower-flow area samples were collected for the full shift on both days

RESULTS AND DISCUSSION

Description of the Mil and the Controls

The miling machine used at this site had 3560 hours on the machine at the beginnng of the site visit It was equipped with water spray nozzles at three places including dr spraying nozzles primar conveyor spraying nozzles and material transfer conveying nozzles There were 18 flat fan spray nozzles (UniJetQI model 11005 SS Spraying Systems Co Wheaton IL) mounted on a spragravey bar in the cutter dru housing This type

of nozzle was used at all of the installations on this milL Thegrave fist thee nozzles on the cutter dr spray bar were mounted 2 inches (in) apar the thrd and fourh nozzle were

mounted 3 in apar and the remaining nozzles were 5 Yi in apar The cutter dr

extension was served by a separate spray bar equipped with thee nozzles The first two nozzles were 2in apar while the second and thrd nozzle were 5 Yi in apar There were a total of nine nozzles at the primary conveyor installed at the transition from the cutter dr to the primar conveyor four were mounted on each side and one on the extension

These nozzles were 1 foot apar There were two nozzles mounted above the material transfer conveyor at the transition from the primar cogravenveyor Those nozzles were 32 in apar New nozzles were installed on the evening before the first sampling day The water pump for the spraying system is rated at 40 Llmin (106 gallons) of water at 3 Yi bar (51 psi)

The 8 ft 6 in wide cutter dr held 193 bits aranged in a helical coil around the dr

holders were in factory spec condition with 50 hrs on the holders NewThe drm and

bits were installed on the evening before the first sampling day and were changed several times durg the next two days The dr rotation was measured and found to agree with

the manufacturers specification of928 rpm

Personal protective equipment and work practices

The miling crew members wore hard hats (except the operator) safety glasses and traffc safety vests The operator was the only employee who spent all of his time on the mil operating the mil from either the right or left side of the operators station The foreman spent the majority of the first day operatig the rear controls while the thid ecircrewman performed tasks such as operating a skid-steer loader and drvig the water

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in the afternoon the foreman operated the skid steer loader while the third crewman ran the rear controls For the most par the skid-steer loader was not operated near the miling machine on the first day On one occasion a road grader passed by and for a brief period in the afternoon nugravellig took place alongside a field while a farer was running a combine On the second day the skid-steer loader

truck (Figure 6) However

the daythe day and the third crew member spent most ofwas idle for the majority of

the rear controls The foreman left the migravelperiodically to attend torunning one of

matters such as trck scheduling On both days the trcks assigned to take away thepossiblethe road unti that was no longermiled material drove on the paved portion of

lessening the potential of dust being generated by the trucks as they passed the millng machine

Respirable dust and crystallne silica sampling results

personal breathing zone sampling for respirable dust and crystalline silica conducted on October 8 are presented in Table 1 On October 8 which represented a typical millng day respirable dust results ranged from 014 to 183 mgm The TW A respirable dust exposures for the three employees were 026 mgmJ (499 minutes) for the

The results of

operator 10 mgm3 (495 minutes) for the foreman and 038 mgm3 (438 minutes) for the third employee who began the day operatin~ the skid steer loader Their 8-hour TWAs were 027 mgm3 for the operator 10 mgm for the foreman and 035 mgm3 for the third crew member The OSHA PELs for these employees calculated based upon the percent silica in their samples were 142 mgm 3 for the operator 117 mgm3 for the foreman and 113 mgm3 for the third member of the miling crew The PELs were calculated using the value of the LODJ for quarz values below the LOD (Hornung and Reed 1990) None of the employees exposures exceeded the OSHA PEL on October 8 as a TW A but excursions above the PEL did take place during the first two sampling periods for the foreman who spent most of those periods operating the rear controls on the mUL

Respirable quarz results from personal samples ranged from below the limit of to

detection 01 1 inglm3 The TW A respirable quarz exposures for October 8 were 0013 mgm3 for the operator 0064 mgm3 for the foreman and 0030 mgm3 for the third

LOD formiling Crew member The TWAs were also calculated using the value of

001 mg Their 8-hour quartz TWAs were 0014 mgm3 0066 mglm3 and 0027 mgm3 respectively On October 8 the foremans TWA and 8-hour TWA exposure exceeded the NIOSH quarz REL of 005 nigm3

quarz results less than the LOD of

the milling crews respirable dust and respirable quartzTable 2 lists the results of

exposures by nozzle type and employee results in TWAs of21 mgm3 for the operator 062 mgm3 for the foreman and 11 mgm3 for the rear control operator for the UniJ etfI 11005 nozzle versus 14 mglm3 065 mgm3 and 089 mgm respectively forthe UniJetaeligl 11008 nozzle TWA

samples on October 9 Calculating TWA respirable dust

the operator 0041

mgm3 for the foreman and 0050 mgin3 for the worker operating the rear controls quartz results for the UniJetfI 11005 nozzle were 012 mgm3 for

8

0081 mgm3 for the operator TW A quarz results for the UniacuteJetlIII008 nozzle were

0041 mgm3 for the foreman and 0043 mgm3 for the thrd crewman In contrast to October 8 the operator received the highest exposures on the second sampling day

Table 3 shows that the highest emissionsthe nozzle type Inspection ofregardless of

side of the mil and the upper conveyor Unfortunately the weather station did not log data so the effect of the wind direction on those results is unnown

were associated with the left

the area samplescoUected on October 8 with the lower-flow respirable dust samplers (17 Lmin) and the pdR direct-reading instruments Those results indicate that for both sampling methods that exposures were lowest igraven the

Table 4 reports the results of

operators station and highest at the upper conveyor (the material transfer conveyor) This table also lists the gravimetricpDR ratios calculated for each sampling location These ratios were used to adjust pDR short teimsampling concentrations which are provided later in ths report Table 5 presents the results for the lower-flow respirable

dust samples and the pdR samples for October 9 including the results from all nozzle types The upper conveyor produced the highest exposure on that day as welL Perhaps the operators personal exposures differ from the area sample at his work station because

the time on one or the other side of the mm while the sampler was in the

he spends most of

his work station (Figure 7) Table 5 which provides the results ofthe center of

lower-flow andpdR area samples shows that as in Table 3 the highest emissions were associated with the left side of the mill and the upper conveyor The migraveU removed

the road so the left side oftlie mm was facing the pavedmaterial from the right side of

the road while the right side faced the previous cut This orientation may explain the milL The manufacturers

edge of

in par why the exposures were higher on the left side of

6 relates area samplingrepresentative attributed this result to passing truck trame Table

results to productivity water flow and water spray pressure while Table 7 describes the work done on October 9

When reviewing the results of sampling conducted on October 9 for the purpose of this study it is useful to compare the results obtained when the different water spray nozzles

logwere used For the purpose ofthisaualysis the results were converted to the natural

the data did not vary with(In) scale because on the log scale the varabmty of

concentration From the In scale analysis of the respirable dust results (Tables 8~ II) the ratio of the UniJ etlf 11005 nozzle to the DniJ et(szlig i 1008 nozzle results is the ratio of their geometric means 12 This indicates that the respirable dust measurements obtained

are about 20 higher thotigh the result is not statistically significant even at the lO signifcance leveL Results for the pDRs are while the UniJetlf 11005 nozzle was used

also about 20 higher for the UnijetQ 11005 and are also notsimilar Those results are

statistically significant at the 10 leveL Examination oftbe tables indicates that for mostthe

groupings the UniJetlIl1005 nozzle does give higher results Review of all of

the UniacuteJet(( 11005 nozzle resultsrespirable dust data from October 9 shows that 59 of

exceeded the PEL while 50 of the UniJetI 11008 nozzle results did so For personal breathing zone samples half of the results while the Unijet(szlig 11005 was in use exceeded

the UnijetlI 11008 results exceeded the PELthe PEL one third of

9

From the In scale analysis of the quarz samplig results (Tables 12-15) the ratio of the Uniet(szlig 11005 nozzle to the Uniet(szlig 11008 nozzle results is the ratio of their geometrc means 116 Thus for respirable quar the results while Uniet(szlig i 1005 nozzles were intalled on the cutter drm were about 16 higher though the result is not statisticaly signficant even at the 10 signcance leveL Examation of the tables indicates that the quar results are not as consistent as those for respirable dust For data from both days 7 respirable quar results were less than the LOD and 13 values were between LOD and LOQ For the seven quarz values below the LOD the value Lan was substituted

Quarz in bulk samples

The results of 10 bulk samples ranged from 12 to 28 with a mean of 199 and a median of 185

CONCLUSIONS AN RECOMMNDATIONS

Conclusions from ths pilot study regardig the effect of increasing the water flow to the spray nozzles on dust and quart exposures are lited by several factors First the higher flow nozzles were only intalled on the cutter dr and the cutter dr extension

the nozzles selected represent a difference of only 30 more flow when the higher-flow nozzles were installed Nevereless the respirable dust measurements obtaied while the Uniet(szlig 11005 nozzles were used were about 20 higher than when the higher-flow Uniet(szlig 11008 nozzles were used The respirable quarz results while Uniet(szlig 11005 nozzles were installed on the cutter dr were about 16 higher Neither

Second

the reductions in respirable dust concentrations nor those for the quarz results were statistically signficant even at the lO signficance leveL Statistical signficance mean that the difference is not due to chance alone

Research on dust controls in minig has shown that water sprays have two roles wetting of broken material being transported and airborne captue (NOSH 2003) Uniformly wetting the broken material durg the breakage process is far more effective and enures that dust paricles stay attached to the materal (NQSH 2003) Increasing the water flow rate and increasing the number of sprays have both been shown to be effective it is tooearly in this proj ect to recommend an approach In one inance dust from a shearer dr was reduced by 60 when the 46 smaler orifice nozzles were substituted for the originall7 nozzles with the pressure and flow held constant (NOSH 2003) The shape of the spray is another importnt factor in its effectveness

Futue studies might test the water system on a newer-model machie to begi to explore the relationship between water flow and pressue agravend aiborne dust concentrtions Varables related to the site andjob might obscure ths relationship but it is hoped that a trend might emerge

10

REFERENCES

29 CFR 19101000 (2001) Occupational Safety and Health Admstration air

containants

29 CFR 192655 (2003) Occupational Safety and Health Adminstration gases vapors fues dusts and mists

ACGrn (2004) Theshold limit values for chemical substances CincinatiOH American Conference of Governental Industral Hygienists

Akbar-Khanadeh F Brillhar RL (2002) Respirable crystallne silca dust exposure durng concrete finshing (grnding) using hand-held grnders in the constrction industr An occup Hyg 46341-346

Bureau of Mines (1992) Crystallne silica primer Washigton DC US Deparent of the Interior Bureau of Mines Branch of Industral Minerals Special Publication

Glindmeyer HW Hamad YY (1988) Contributing factors to sandblasters silcosis inadequate respiratory protection equipment and standards J accup Med 30917-921

HSE (1997) MDHS 142 General methods for sampling and gravimetrc analysis of respirable and total inhalable dust Methods for the determination of hazardous substances lIealth and safety laboratory Sudbur Suffolk UK Health and Safety Executive

Homuug R Reed L (1990) Estimation of average concentration in the presence of nondetectable values Applied Occupational and Environmental Hygiene 5(1)46-51

Linch KD (2002) Respirable concrete dust-silcosis hazard in the constrction industr

Appl Occup and Environ Hyg 17 209-221

Neuhauser Curt (curneuhauser(ecircdotstatewius) (2004) RE US 12 project Private e-mail message to Alan Echt (AEcht(ecirccdcgov) Januar 7

New Jersey Deparent of Health and Senior Services (2001) New Jersey silica parership In Occupational Health Sureilance Update February Trenton NJ NJ

Deparment of Health and Senior Services Division of Epidemiology Environmental and Occupational Health Occupational Health Service Occupational Health Sureilance Program

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ACKNOWLEDGMENT

The authors than the National Asphalt Pavement Association Silca Parership for their efforts on behalf of ths study and for their assistance in aranging this site visit

iv

ABSTRACT

A pilot study was performed to evaluate the effectiveness of water spray controls for a cold miling machine The objective of ths study was to quantify the exposure reduction that could be achieved through the use of higher flow water-spray nozzles durng pavement miling The effectiveness of the dust controls examned in ths study was evaluated by measurng the reduction in the respirable dust and resprrable quart exposures in personal and area samples collected durg a typical milling job Use ofthe higher flow nozzles resulted in reductions in respirable dust and respirable quar exposures but the differences were not statistically signficant Durng this study the higher flow nozzles were only installed on the cutter dr and the cutter drm extension

v

INTRODUCTION

The National Institute for Occupational Safety and Health (NOSH) is located in the Centers for Disease Control and Prevention (CDe) par of the Deparent of Health and Human Services (DHHS) NIOSH was established in 1970 by the Occupational Safety and Health Act at the same time that the Occupational Safety and Health Adminstration

Labor (DOL) The OSH Act legislation mandated NIOSH to conduct research and education programs separate from the standard-setting and enforcement fuctions conducted by OSHA An important area of NIaSH research deals with methods for controllng occupational exposure to potential chemical and physical hazards

(OSHA) was established in the Deparent of

The Engineering and Physical Hazards Branch (EPHB) of the Division of Applied Research and Technology (DART) has been given the lead within NIOSH to study and develop engineering controls and assess their impact on reducing occupational ilness Since 1976 EPHB (and its predecessor the Engineering Control Technology Branch) has conducted a large number of studies to evaluate engineerig control technology based upon industr process or control technique The objective of each ofthese studies has

been to evaluate and document control techniques and to determine their effectiveness in reducing potential health hazards in an industr or for a specific process

The primary aim of this project is to determine if the engineering controls supplied with new miling machines and operated according to the manufactuers recommendations are adequate to control worker exposures to respirable dust and respirable crystallne silca (in the fonI of quarz) The long term goal of ths project is to reduce worker exposures to silica hy providing data to support the development of a set of practice guidelines for the equipment if the engineering controls are adequate or to develop a set

best

of recommendations to improve the performance of controls if they are not adequate

Many constrction tasks have been associated with overexposure to crystalline silca (Rappaport et al 2003) Among these tasks are tuck pointing concrete sawing concrete grding and abrasive blasting (NIOSH 2000 Thorpe et aL 1999 Akbar-Kanadeh andBrillhar 2002 Glindmeyer and Hamad 1988) Road miling has also been shown to result in overexposures to respirable crystallne silca (Linch 2002 Rappaport et aL 2003 NJ Dept of Health and Senior Services 2001) However all three of the road-miling studies are limited because they do not provide enough information about the operating parameters and engineering controls present on the miling machies to determine if the overexposures were due to a lack of effective controls or poor work practices This study wil attempt to fill that knowledge gap

A varety of machinery and work practices are employed in asphalt pavement recycling includng cold-planers heater planers cold-millers and heater-scarfiers (public Works 1995) Cold-millng which uses a toothed rotating dr to grind and remove the

1

pavement to be recycled is primarily used to remove surface deterioration on both asphalt and Portland cement concrete road surfaces (public Works 1995) The millng machines used in cold miling are the fociis ofthis investigation

the US 12The cold miling work observed durng ths piacutelot study was par of

section ofreconstruction project from CTH KP to STH 19 west in Wisconsin This was a

old US 12 that was rehabiltated and wil be tranferred to the local township There was a 20 ft wide concrete pavement placed in the early 1900s Above that was a layer of

varying thickness about 0 inches to 10 inches Above that was varying asphaIgravet pavement thiclmess of about 8 to more than 12 inches which had crushed aggregate base course of

been placed at varous times in about the last 60 years The asphaltic pavement was rutted and cracked to varying degrees The portion of old US 12 from Simpson Road to the south where it meets the new US 12 was re-graded on new alignent this pavement removal was specified by a Common Excavation item The Common Excavation item specification enables the contractor to remove the pavement in any way they see fit In this case the contractor chose to mill the pavement because it was of value

removed and disposed of In the area from Simpson to the nort this section was not re-graded but the entigravere existing asphaltic pavement was removed under the item of Removing Asphaltic Surface This specifies the removal of only the asphaltic pavement Again the contractor chose

as a recycled product The existing concrete was also

and recycle it (Neuhauser 2004)to salvage this pavement

This study was faciltated by a partership in cooperation with the National Asphalt Pavement Assocation that includes millng machine manufacturers contractors employee

the millng machinerepresentatives NIOSH and other interested paries One of

study on a 2003 miacuteling machine model with the latest state-of-the-ar water spraying system produced by the manufacturer The mill is a half-lane miling machine rated at 560HP with a water spray system capable of l5gpm at 200psI This system was put into production in 2001 - before initial discussions on testing airborne dust concentration

manufacturers manufacturer A had initially arranged to perform the pilot

About one week before the pilot study was to be performed manufacturer A leared that the 2003 mil would not be available for the test Instead an older machine was substituted The replacement machine was a half-lane millng machine rated at 800 HP with an eight-foot cutter and an older model water system designed for i Ogpm at 50psi

Manufacturer A knew that the lower water flow at much lower pressure would result in higher airborne dust content hut Manufacturer A was stil confident that the dust suppression system even on the older model machines should still be very effective if properly maintained and operated Therefore Manufacturer A agreed to perform the test (even with the last minute changes) as a means of getting at least a good baseline for this type of airborne dust test

2

OCCUPATIONAL EXPOSUR TO CRYSTALLIN SILICA

Silcosis is an occupational respiratory disease caused by inaling respirable crystalline

silca dust Silcosis is irreversible often progressive (even after exposure has ceased)

and potentially fataL Because no effective treatment exists for silicosis prevention though exposure control is essentiaL Exposure to respirable crystalline silca dust occurs in many occupations including constrction Crystalline silca refers to a group of minerals composed of silcon and oxygen a crystalline strctue is one in which the atoms are aranged in a repeating three-dimensional pattern (Bureau of Mines 1992) The three major forms of crystalline silca are quartz cristobalite and trdymite quar is the most common form (Bureau of Mines 1992) Respirable refers to that portion of airborne crystalline silca that is capable of entering the gas-exchange regions of the lungs if inhaled this includes paricles with aerodynamc diameters less than approximately 10

Ilm (NOSH 2002)

When proper practices are not followed or controls are not maintained respirable crystallne silica exposures can exceed the NIaSH Recommended Exposure Limit

Permssible Exposure Limit (PEL) or the American Conference of(RL) the OSHA

Governental Industral Hygienists (ACGIH) Threshold Limit Value (TLV) (NOSH 200229 CFR 19101000 ACGll 2004) NiaSH recommends an exposure limit of 005 mgm3 to reduce the risk of developing silicosis lung cancer and other adverse health effects

The OSHA PEL for respirable dust containing 1 quarz or more in general industr is expressed as an equation (29 CFR 19101000)

10 mgm3 Respirable PEL =

Silca + 2

If for example the dust contai no crystalline silica the PEL is 5 mgm3 and if the dust is 100 crystalline silca the PEL is 01 mgm3 For trdymite and cristobalite OSHA uses half the value calculated using the formula for quarz (29 CPR 19101000)

The curent OSHA permissible exposure limit (PEL) for respirable dust containng crystallne silica (quartz) for the constrction industr is measured by impinger sampling The PEL is expressed in millons of paricles per cubic foot (mppcf) and is calculated using the following formula (29 CFR 192655)

250 mppcf Respirable PEL =

Silca + 5

3

Since the PELs were adopted the impinger sampling method ha been rendered obsolete by gravimetrc sampling (OSHA 1996) OSHA is not aware of any goverent agencies or employers in ths countr that are curently usng impinger sampling to assess worker

exposure to dust containig crystallne silca and impinger samples are generally

recogned as being less reliable than gravimetrc samples (OSHA 1996) OSHA has determed that sampling procedures in the consction industr should be the same as in general industr and that the mppcfPEL in 29 CFR 192655(a) is equivalent to the mgm3 PEL in 29 CFR 19101000 (aSHA 1996)

The ACGrnCE TL VIs for cristobalte quar and trdymte are all 005 mglm3 (ACGm 2004) The ACGrn~ ha published a notice of their intent to change the TL ~ for (Xshyquar and cristobalte (respirable fraction) to 0025 mgm3 and to withdraw the documentation and adopted TL yi for trdymte (ACGrn 2004)

METHODS

Descriptive data about the millig machie were gathered durng the aferoon and evening prior to the fist day of sampling while the machie was undergoing repais at the Payne amp Dolan shop Information was collected about the number tye condition and placement of water spray nozzles on thedr and at the conveyor belt tranitions the cutter dr rotation rate (measured using a non-contact tachometer (T AC2K Dwyer Instrents Inc Michigan City Indiana) while the mill was rug) the hours on the machie the cutter dr condition and the cutter bits including their spacing condition make and model number NIOSH personnel worked with Payne amp Dolan sta and the manufactuers representative to install water flow meters and pressure gauges install new water spray nozzles and cutter bits and restore the water spray nozzles at the seconda conveyor tranition to the manufactuers specification This tie was also used to lear aboutthe operation of the machie and safe work practices

Water flow rate was measured using two water flow meters (Confowmeter II Confow Inc WashigtonP A) intaled in the water supply lies on the milL One meter was installed in the line between the water pump and the cutter dr spray bar The second meter was installed in the line between the water pump and the conveyor transition sprays (Figure 1 ) Water pressure was measured using pressure gauges attched to tee-fittgs

instaled in the water lie supplyig the cutter dr spray bar (Figue 2) in the water line

supplyigthe spray bar for the fist conveyor belt tranition and in the water lie supplyig the nozzles on the secondar conveyor transition The readings on thesemeters and gauges were obsered and recorded periodicaly thoughout both days of millig

Vehic1e speed and diection of trvel was meased using a Trible GeoXT hadheld data-loggig global positionig system (GPS) unt (Trible Navigation Ltd Sunyvale CA) receiver on the second day of millig The GPS unt was placed on padding on the top of the millig machie in an empty fi-extiguisher bracket (the extingusher had been relocated previously) in front of the operators station (Figue 3) Speed was also

4

observing and recording the foot speed reading on the intrent panel ofthe mil every two minutes As a measure recorded durng both days of miling by a NIOSH researcher

of productivity the time was recorded when each dump truck was loaded and pulled away from the millng machine

Depth of cut was measurecl every fifteen minutes during both milling days using a tape measure helcl at the edge of the cut pavement The width of the cut was measured as well Bulk samples of the miled pavement were collected on a periodic basis from

left in or next to the cut by the milling machine Wind speed and direction and temperature were recorded usigraveng a data-loggigraveug weather station (MultiLog Weather material

Station Fourier Systems Inc Atlanta GA) A hand-held muitigrave~directional impeller wind meter was also used during the survey (Skywatch Meteos JDC Electronic SA Yverdon-Ies-Bains Switzerland)

The work practices and use of personal protective equipment were recorded for each worker sampled including the workers position and distance relative to the miling machine (eg walking alongside following behind riding) Infomiation obtained from conversations with worlcers to detennine if the sampling days were typical of the nomial work load helped to place the sampling results in proper perspective Data were recorded describing other operations nearby that generated dust including the process its location relatIacuteve to the miling machine and whether it was upwind or downwind of the millng machine

Dust and Silca Sampling Methods

On both days of sampling personal breathing zone samples on the three members of the miling crew were collected at a flow rate of 42 liters per minute (Umin) using a battery-operated sampling pump at the employees waist connected via flexible tubing to a pre-weighed 37-mm diameter 5-micron (~m) pore-size polyvinyl chloride filter supported by a backup pad in a three-piece filter cassette sealed with a cellulose shrink band in accordance with NIOSH Methods 0600 and 7500 and a cyclone (GK 269 RespirableThoracic Cyclone BGi Inc Waltham MA) placed in the employees breathing zone (NIOSH 1994 HSE 1997)

Area samples were collected on both days of sampling at six locations on the millng instruments mounted on a metal frame (Figure 4) Themachine using an aray of

platform near the level controls onlocations included the dashboard on the operators

both sides of the mil near the cutter dr on both sides of the mil and on the right side

conveyor to the loading conveyor (Figure 5) The sampling intruments in each aray included a Ii ght-scattering aerosol photometer (pDR near the transition from the primary

Theano Electron Corp Franklin MA) with a 10 millmeter (mm) nylon cyclone comiected to the inlet via flexible tubing The pDR was in tur connected via flexible tubing to a battery-operated sampling pump calibrated at a flow rate of 17 Llmin A pre-weighed 5-~m pore-size polyvinyl chloride filter supported by a backup pad in a two-piece filter cassette sealed with a cellulose shr band was placed in line between the

5

pDR and the pump Also included in each sampling aray were two battery-operated sampling pumps both connected though flexible tubing to a 10-mm nylon cyclone and a pre-weighed 37-mm diameter 5-iexclm pore-size polyvnyl chloride filter supported by a backup pad in a two-piece filter cassette sealed with a cellulose shn band in accordance with NIOSH Methods 0600 and 7500

On the second day of sampling addigravetional area sauiples were collected at the six locations described above at a flow rate of 42 litersminute using a battery-operated sampling pump connected via flexible tubing to a pre-weighed 37-mm diameter 5shymicron (iexclm) pore-size polyvinyl chloride filter supported by a backup pad in a three-piece fiter cassette sealed with a cellulose shrink band in accordance with NIOSH Methods 0600 and 7500 and a cyclone (OK 269 RespirableThoracic Cyclone BGI Inc Waltham MA) attached to the metal frame

Gravimetric analysis for respirable pariculate was cared out with the fOllOWing modifications to NIOSH Method 0600 1) the fiters and backup pads were stored in an environmentally controlled room (201 1degC and 50i5 relative humidity) and were subj ected to the room conditions for at least two hours for stabilization prior to tare and gross weighing and 2) two weighings of the tare weight and gross weight were performed (NIOSH 1994) The difference between the average gross weight and the average tare weight was the result of the analysis The limit of detection for this method was 002 mg

Crystalline silica analysis ofthehigravegher-flow fiter and all bulk samples was perfornied using X-ray diffraction NIOSHMethod 7500 was used ith the following modifications 1) fiters were dissolved in tetraIgraveydrofurail rather than being ashed in a furace and 2) standards and samples were run concurently and an external calibration ciire was prepared from the integrated intensities rather than using the suggested normalization procedure (NIOSH 1994) These samples were analyzed for quarz and cristobalite The limits of detection for quarz and cristobalite on filters were 001 and 002 mg respectively The limit of quantiation is 003 mg for both quarz and cristobalite The lower-flow filter samples were not analyzed for silica

bulk samples collected from miled pavement left in or next to the cut by the millng machine The limit of detection for quar in bulk samples was 08 The limit of quantitation was 2

The silica content of the pavement was determined though testing of

Experimental design

Initial activities on site such as installing new water spray nozzles and new cutter-drm teeth were devoted to returing the mil to the manufacturers specifications DulIgraveng the

first day of sampling samples were collected over thee sampliacuteng periods during a typical miling job The second day of sampling was divided into four 2-hour periods During

the first period the manufacturer-specified nozzles (UniJetll model1 005 SS Spraying Systems Co Wheaton IL) rated at 05 gallons per minute (gpm) at 40 pounds per square

6

inch (psi) were used For the second and thd period higher-flow nozzles CUniJ etQI

model 11008 Spraying System Co Wheaton IL) rated at 08 gpm at 40 psi were installed on the cutter-dr spray bar Durng the final period the manufactuershy

specified nozzles were used again This design was used instead of a randomized design because of the length of time and effort required to change the nozzles in the field The spray nozzles for the primar conveyor and the material transfer conveyor were not changed Personal and high-flow area samples for respirable dust and respirable crystallne silica were changed approximately every two hours durig both sampling days The lower-flow area samples were collected for the full shift on both days

RESULTS AND DISCUSSION

Description of the Mil and the Controls

The miling machine used at this site had 3560 hours on the machine at the beginnng of the site visit It was equipped with water spray nozzles at three places including dr spraying nozzles primar conveyor spraying nozzles and material transfer conveying nozzles There were 18 flat fan spray nozzles (UniJetQI model 11005 SS Spraying Systems Co Wheaton IL) mounted on a spragravey bar in the cutter dru housing This type

of nozzle was used at all of the installations on this milL Thegrave fist thee nozzles on the cutter dr spray bar were mounted 2 inches (in) apar the thrd and fourh nozzle were

mounted 3 in apar and the remaining nozzles were 5 Yi in apar The cutter dr

extension was served by a separate spray bar equipped with thee nozzles The first two nozzles were 2in apar while the second and thrd nozzle were 5 Yi in apar There were a total of nine nozzles at the primary conveyor installed at the transition from the cutter dr to the primar conveyor four were mounted on each side and one on the extension

These nozzles were 1 foot apar There were two nozzles mounted above the material transfer conveyor at the transition from the primar cogravenveyor Those nozzles were 32 in apar New nozzles were installed on the evening before the first sampling day The water pump for the spraying system is rated at 40 Llmin (106 gallons) of water at 3 Yi bar (51 psi)

The 8 ft 6 in wide cutter dr held 193 bits aranged in a helical coil around the dr

holders were in factory spec condition with 50 hrs on the holders NewThe drm and

bits were installed on the evening before the first sampling day and were changed several times durg the next two days The dr rotation was measured and found to agree with

the manufacturers specification of928 rpm

Personal protective equipment and work practices

The miling crew members wore hard hats (except the operator) safety glasses and traffc safety vests The operator was the only employee who spent all of his time on the mil operating the mil from either the right or left side of the operators station The foreman spent the majority of the first day operatig the rear controls while the thid ecircrewman performed tasks such as operating a skid-steer loader and drvig the water

7

in the afternoon the foreman operated the skid steer loader while the third crewman ran the rear controls For the most par the skid-steer loader was not operated near the miling machine on the first day On one occasion a road grader passed by and for a brief period in the afternoon nugravellig took place alongside a field while a farer was running a combine On the second day the skid-steer loader

truck (Figure 6) However

the daythe day and the third crew member spent most ofwas idle for the majority of

the rear controls The foreman left the migravelperiodically to attend torunning one of

matters such as trck scheduling On both days the trcks assigned to take away thepossiblethe road unti that was no longermiled material drove on the paved portion of

lessening the potential of dust being generated by the trucks as they passed the millng machine

Respirable dust and crystallne silica sampling results

personal breathing zone sampling for respirable dust and crystalline silica conducted on October 8 are presented in Table 1 On October 8 which represented a typical millng day respirable dust results ranged from 014 to 183 mgm The TW A respirable dust exposures for the three employees were 026 mgmJ (499 minutes) for the

The results of

operator 10 mgm3 (495 minutes) for the foreman and 038 mgm3 (438 minutes) for the third employee who began the day operatin~ the skid steer loader Their 8-hour TWAs were 027 mgm3 for the operator 10 mgm for the foreman and 035 mgm3 for the third crew member The OSHA PELs for these employees calculated based upon the percent silica in their samples were 142 mgm 3 for the operator 117 mgm3 for the foreman and 113 mgm3 for the third member of the miling crew The PELs were calculated using the value of the LODJ for quarz values below the LOD (Hornung and Reed 1990) None of the employees exposures exceeded the OSHA PEL on October 8 as a TW A but excursions above the PEL did take place during the first two sampling periods for the foreman who spent most of those periods operating the rear controls on the mUL

Respirable quarz results from personal samples ranged from below the limit of to

detection 01 1 inglm3 The TW A respirable quarz exposures for October 8 were 0013 mgm3 for the operator 0064 mgm3 for the foreman and 0030 mgm3 for the third

LOD formiling Crew member The TWAs were also calculated using the value of

001 mg Their 8-hour quartz TWAs were 0014 mgm3 0066 mglm3 and 0027 mgm3 respectively On October 8 the foremans TWA and 8-hour TWA exposure exceeded the NIOSH quarz REL of 005 nigm3

quarz results less than the LOD of

the milling crews respirable dust and respirable quartzTable 2 lists the results of

exposures by nozzle type and employee results in TWAs of21 mgm3 for the operator 062 mgm3 for the foreman and 11 mgm3 for the rear control operator for the UniJ etfI 11005 nozzle versus 14 mglm3 065 mgm3 and 089 mgm respectively forthe UniJetaeligl 11008 nozzle TWA

samples on October 9 Calculating TWA respirable dust

the operator 0041

mgm3 for the foreman and 0050 mgin3 for the worker operating the rear controls quartz results for the UniJetfI 11005 nozzle were 012 mgm3 for

8

0081 mgm3 for the operator TW A quarz results for the UniacuteJetlIII008 nozzle were

0041 mgm3 for the foreman and 0043 mgm3 for the thrd crewman In contrast to October 8 the operator received the highest exposures on the second sampling day

Table 3 shows that the highest emissionsthe nozzle type Inspection ofregardless of

side of the mil and the upper conveyor Unfortunately the weather station did not log data so the effect of the wind direction on those results is unnown

were associated with the left

the area samplescoUected on October 8 with the lower-flow respirable dust samplers (17 Lmin) and the pdR direct-reading instruments Those results indicate that for both sampling methods that exposures were lowest igraven the

Table 4 reports the results of

operators station and highest at the upper conveyor (the material transfer conveyor) This table also lists the gravimetricpDR ratios calculated for each sampling location These ratios were used to adjust pDR short teimsampling concentrations which are provided later in ths report Table 5 presents the results for the lower-flow respirable

dust samples and the pdR samples for October 9 including the results from all nozzle types The upper conveyor produced the highest exposure on that day as welL Perhaps the operators personal exposures differ from the area sample at his work station because

the time on one or the other side of the mm while the sampler was in the

he spends most of

his work station (Figure 7) Table 5 which provides the results ofthe center of

lower-flow andpdR area samples shows that as in Table 3 the highest emissions were associated with the left side of the mill and the upper conveyor The migraveU removed

the road so the left side oftlie mm was facing the pavedmaterial from the right side of

the road while the right side faced the previous cut This orientation may explain the milL The manufacturers

edge of

in par why the exposures were higher on the left side of

6 relates area samplingrepresentative attributed this result to passing truck trame Table

results to productivity water flow and water spray pressure while Table 7 describes the work done on October 9

When reviewing the results of sampling conducted on October 9 for the purpose of this study it is useful to compare the results obtained when the different water spray nozzles

logwere used For the purpose ofthisaualysis the results were converted to the natural

the data did not vary with(In) scale because on the log scale the varabmty of

concentration From the In scale analysis of the respirable dust results (Tables 8~ II) the ratio of the UniJ etlf 11005 nozzle to the DniJ et(szlig i 1008 nozzle results is the ratio of their geometric means 12 This indicates that the respirable dust measurements obtained

are about 20 higher thotigh the result is not statistically significant even at the lO signifcance leveL Results for the pDRs are while the UniJetlf 11005 nozzle was used

also about 20 higher for the UnijetQ 11005 and are also notsimilar Those results are

statistically significant at the 10 leveL Examination oftbe tables indicates that for mostthe

groupings the UniJetlIl1005 nozzle does give higher results Review of all of

the UniacuteJet(( 11005 nozzle resultsrespirable dust data from October 9 shows that 59 of

exceeded the PEL while 50 of the UniJetI 11008 nozzle results did so For personal breathing zone samples half of the results while the Unijet(szlig 11005 was in use exceeded

the UnijetlI 11008 results exceeded the PELthe PEL one third of

9

From the In scale analysis of the quarz samplig results (Tables 12-15) the ratio of the Uniet(szlig 11005 nozzle to the Uniet(szlig 11008 nozzle results is the ratio of their geometrc means 116 Thus for respirable quar the results while Uniet(szlig i 1005 nozzles were intalled on the cutter drm were about 16 higher though the result is not statisticaly signficant even at the 10 signcance leveL Examation of the tables indicates that the quar results are not as consistent as those for respirable dust For data from both days 7 respirable quar results were less than the LOD and 13 values were between LOD and LOQ For the seven quarz values below the LOD the value Lan was substituted

Quarz in bulk samples

The results of 10 bulk samples ranged from 12 to 28 with a mean of 199 and a median of 185

CONCLUSIONS AN RECOMMNDATIONS

Conclusions from ths pilot study regardig the effect of increasing the water flow to the spray nozzles on dust and quart exposures are lited by several factors First the higher flow nozzles were only intalled on the cutter dr and the cutter dr extension

the nozzles selected represent a difference of only 30 more flow when the higher-flow nozzles were installed Nevereless the respirable dust measurements obtaied while the Uniet(szlig 11005 nozzles were used were about 20 higher than when the higher-flow Uniet(szlig 11008 nozzles were used The respirable quarz results while Uniet(szlig 11005 nozzles were installed on the cutter dr were about 16 higher Neither

Second

the reductions in respirable dust concentrations nor those for the quarz results were statistically signficant even at the lO signficance leveL Statistical signficance mean that the difference is not due to chance alone

Research on dust controls in minig has shown that water sprays have two roles wetting of broken material being transported and airborne captue (NOSH 2003) Uniformly wetting the broken material durg the breakage process is far more effective and enures that dust paricles stay attached to the materal (NQSH 2003) Increasing the water flow rate and increasing the number of sprays have both been shown to be effective it is tooearly in this proj ect to recommend an approach In one inance dust from a shearer dr was reduced by 60 when the 46 smaler orifice nozzles were substituted for the originall7 nozzles with the pressure and flow held constant (NOSH 2003) The shape of the spray is another importnt factor in its effectveness

Futue studies might test the water system on a newer-model machie to begi to explore the relationship between water flow and pressue agravend aiborne dust concentrtions Varables related to the site andjob might obscure ths relationship but it is hoped that a trend might emerge

10

REFERENCES

29 CFR 19101000 (2001) Occupational Safety and Health Admstration air

containants

29 CFR 192655 (2003) Occupational Safety and Health Adminstration gases vapors fues dusts and mists

ACGrn (2004) Theshold limit values for chemical substances CincinatiOH American Conference of Governental Industral Hygienists

Akbar-Khanadeh F Brillhar RL (2002) Respirable crystallne silca dust exposure durng concrete finshing (grnding) using hand-held grnders in the constrction industr An occup Hyg 46341-346

Bureau of Mines (1992) Crystallne silica primer Washigton DC US Deparent of the Interior Bureau of Mines Branch of Industral Minerals Special Publication

Glindmeyer HW Hamad YY (1988) Contributing factors to sandblasters silcosis inadequate respiratory protection equipment and standards J accup Med 30917-921

HSE (1997) MDHS 142 General methods for sampling and gravimetrc analysis of respirable and total inhalable dust Methods for the determination of hazardous substances lIealth and safety laboratory Sudbur Suffolk UK Health and Safety Executive

Homuug R Reed L (1990) Estimation of average concentration in the presence of nondetectable values Applied Occupational and Environmental Hygiene 5(1)46-51

Linch KD (2002) Respirable concrete dust-silcosis hazard in the constrction industr

Appl Occup and Environ Hyg 17 209-221

Neuhauser Curt (curneuhauser(ecircdotstatewius) (2004) RE US 12 project Private e-mail message to Alan Echt (AEcht(ecirccdcgov) Januar 7

New Jersey Deparent of Health and Senior Services (2001) New Jersey silica parership In Occupational Health Sureilance Update February Trenton NJ NJ

Deparment of Health and Senior Services Division of Epidemiology Environmental and Occupational Health Occupational Health Service Occupational Health Sureilance Program

11

ABSTRACT

A pilot study was performed to evaluate the effectiveness of water spray controls for a cold miling machine The objective of ths study was to quantify the exposure reduction that could be achieved through the use of higher flow water-spray nozzles durng pavement miling The effectiveness of the dust controls examned in ths study was evaluated by measurng the reduction in the respirable dust and resprrable quart exposures in personal and area samples collected durg a typical milling job Use ofthe higher flow nozzles resulted in reductions in respirable dust and respirable quar exposures but the differences were not statistically signficant Durng this study the higher flow nozzles were only installed on the cutter dr and the cutter drm extension

v

INTRODUCTION

The National Institute for Occupational Safety and Health (NOSH) is located in the Centers for Disease Control and Prevention (CDe) par of the Deparent of Health and Human Services (DHHS) NIOSH was established in 1970 by the Occupational Safety and Health Act at the same time that the Occupational Safety and Health Adminstration

Labor (DOL) The OSH Act legislation mandated NIOSH to conduct research and education programs separate from the standard-setting and enforcement fuctions conducted by OSHA An important area of NIaSH research deals with methods for controllng occupational exposure to potential chemical and physical hazards

(OSHA) was established in the Deparent of

The Engineering and Physical Hazards Branch (EPHB) of the Division of Applied Research and Technology (DART) has been given the lead within NIOSH to study and develop engineering controls and assess their impact on reducing occupational ilness Since 1976 EPHB (and its predecessor the Engineering Control Technology Branch) has conducted a large number of studies to evaluate engineerig control technology based upon industr process or control technique The objective of each ofthese studies has

been to evaluate and document control techniques and to determine their effectiveness in reducing potential health hazards in an industr or for a specific process

The primary aim of this project is to determine if the engineering controls supplied with new miling machines and operated according to the manufactuers recommendations are adequate to control worker exposures to respirable dust and respirable crystallne silca (in the fonI of quarz) The long term goal of ths project is to reduce worker exposures to silica hy providing data to support the development of a set of practice guidelines for the equipment if the engineering controls are adequate or to develop a set

best

of recommendations to improve the performance of controls if they are not adequate

Many constrction tasks have been associated with overexposure to crystalline silca (Rappaport et al 2003) Among these tasks are tuck pointing concrete sawing concrete grding and abrasive blasting (NIOSH 2000 Thorpe et aL 1999 Akbar-Kanadeh andBrillhar 2002 Glindmeyer and Hamad 1988) Road miling has also been shown to result in overexposures to respirable crystallne silca (Linch 2002 Rappaport et aL 2003 NJ Dept of Health and Senior Services 2001) However all three of the road-miling studies are limited because they do not provide enough information about the operating parameters and engineering controls present on the miling machies to determine if the overexposures were due to a lack of effective controls or poor work practices This study wil attempt to fill that knowledge gap

A varety of machinery and work practices are employed in asphalt pavement recycling includng cold-planers heater planers cold-millers and heater-scarfiers (public Works 1995) Cold-millng which uses a toothed rotating dr to grind and remove the

1

pavement to be recycled is primarily used to remove surface deterioration on both asphalt and Portland cement concrete road surfaces (public Works 1995) The millng machines used in cold miling are the fociis ofthis investigation

the US 12The cold miling work observed durng ths piacutelot study was par of

section ofreconstruction project from CTH KP to STH 19 west in Wisconsin This was a

old US 12 that was rehabiltated and wil be tranferred to the local township There was a 20 ft wide concrete pavement placed in the early 1900s Above that was a layer of

varying thickness about 0 inches to 10 inches Above that was varying asphaIgravet pavement thiclmess of about 8 to more than 12 inches which had crushed aggregate base course of

been placed at varous times in about the last 60 years The asphaltic pavement was rutted and cracked to varying degrees The portion of old US 12 from Simpson Road to the south where it meets the new US 12 was re-graded on new alignent this pavement removal was specified by a Common Excavation item The Common Excavation item specification enables the contractor to remove the pavement in any way they see fit In this case the contractor chose to mill the pavement because it was of value

removed and disposed of In the area from Simpson to the nort this section was not re-graded but the entigravere existing asphaltic pavement was removed under the item of Removing Asphaltic Surface This specifies the removal of only the asphaltic pavement Again the contractor chose

as a recycled product The existing concrete was also

and recycle it (Neuhauser 2004)to salvage this pavement

This study was faciltated by a partership in cooperation with the National Asphalt Pavement Assocation that includes millng machine manufacturers contractors employee

the millng machinerepresentatives NIOSH and other interested paries One of

study on a 2003 miacuteling machine model with the latest state-of-the-ar water spraying system produced by the manufacturer The mill is a half-lane miling machine rated at 560HP with a water spray system capable of l5gpm at 200psI This system was put into production in 2001 - before initial discussions on testing airborne dust concentration

manufacturers manufacturer A had initially arranged to perform the pilot

About one week before the pilot study was to be performed manufacturer A leared that the 2003 mil would not be available for the test Instead an older machine was substituted The replacement machine was a half-lane millng machine rated at 800 HP with an eight-foot cutter and an older model water system designed for i Ogpm at 50psi

Manufacturer A knew that the lower water flow at much lower pressure would result in higher airborne dust content hut Manufacturer A was stil confident that the dust suppression system even on the older model machines should still be very effective if properly maintained and operated Therefore Manufacturer A agreed to perform the test (even with the last minute changes) as a means of getting at least a good baseline for this type of airborne dust test

2

OCCUPATIONAL EXPOSUR TO CRYSTALLIN SILICA

Silcosis is an occupational respiratory disease caused by inaling respirable crystalline

silca dust Silcosis is irreversible often progressive (even after exposure has ceased)

and potentially fataL Because no effective treatment exists for silicosis prevention though exposure control is essentiaL Exposure to respirable crystalline silca dust occurs in many occupations including constrction Crystalline silca refers to a group of minerals composed of silcon and oxygen a crystalline strctue is one in which the atoms are aranged in a repeating three-dimensional pattern (Bureau of Mines 1992) The three major forms of crystalline silca are quartz cristobalite and trdymite quar is the most common form (Bureau of Mines 1992) Respirable refers to that portion of airborne crystalline silca that is capable of entering the gas-exchange regions of the lungs if inhaled this includes paricles with aerodynamc diameters less than approximately 10

Ilm (NOSH 2002)

When proper practices are not followed or controls are not maintained respirable crystallne silica exposures can exceed the NIaSH Recommended Exposure Limit

Permssible Exposure Limit (PEL) or the American Conference of(RL) the OSHA

Governental Industral Hygienists (ACGIH) Threshold Limit Value (TLV) (NOSH 200229 CFR 19101000 ACGll 2004) NiaSH recommends an exposure limit of 005 mgm3 to reduce the risk of developing silicosis lung cancer and other adverse health effects

The OSHA PEL for respirable dust containing 1 quarz or more in general industr is expressed as an equation (29 CFR 19101000)

10 mgm3 Respirable PEL =

Silca + 2

If for example the dust contai no crystalline silica the PEL is 5 mgm3 and if the dust is 100 crystalline silca the PEL is 01 mgm3 For trdymite and cristobalite OSHA uses half the value calculated using the formula for quarz (29 CPR 19101000)

The curent OSHA permissible exposure limit (PEL) for respirable dust containng crystallne silica (quartz) for the constrction industr is measured by impinger sampling The PEL is expressed in millons of paricles per cubic foot (mppcf) and is calculated using the following formula (29 CFR 192655)

250 mppcf Respirable PEL =

Silca + 5

3

Since the PELs were adopted the impinger sampling method ha been rendered obsolete by gravimetrc sampling (OSHA 1996) OSHA is not aware of any goverent agencies or employers in ths countr that are curently usng impinger sampling to assess worker

exposure to dust containig crystallne silca and impinger samples are generally

recogned as being less reliable than gravimetrc samples (OSHA 1996) OSHA has determed that sampling procedures in the consction industr should be the same as in general industr and that the mppcfPEL in 29 CFR 192655(a) is equivalent to the mgm3 PEL in 29 CFR 19101000 (aSHA 1996)

The ACGrnCE TL VIs for cristobalte quar and trdymte are all 005 mglm3 (ACGm 2004) The ACGrn~ ha published a notice of their intent to change the TL ~ for (Xshyquar and cristobalte (respirable fraction) to 0025 mgm3 and to withdraw the documentation and adopted TL yi for trdymte (ACGrn 2004)

METHODS

Descriptive data about the millig machie were gathered durng the aferoon and evening prior to the fist day of sampling while the machie was undergoing repais at the Payne amp Dolan shop Information was collected about the number tye condition and placement of water spray nozzles on thedr and at the conveyor belt tranitions the cutter dr rotation rate (measured using a non-contact tachometer (T AC2K Dwyer Instrents Inc Michigan City Indiana) while the mill was rug) the hours on the machie the cutter dr condition and the cutter bits including their spacing condition make and model number NIOSH personnel worked with Payne amp Dolan sta and the manufactuers representative to install water flow meters and pressure gauges install new water spray nozzles and cutter bits and restore the water spray nozzles at the seconda conveyor tranition to the manufactuers specification This tie was also used to lear aboutthe operation of the machie and safe work practices

Water flow rate was measured using two water flow meters (Confowmeter II Confow Inc WashigtonP A) intaled in the water supply lies on the milL One meter was installed in the line between the water pump and the cutter dr spray bar The second meter was installed in the line between the water pump and the conveyor transition sprays (Figure 1 ) Water pressure was measured using pressure gauges attched to tee-fittgs

instaled in the water lie supplyig the cutter dr spray bar (Figue 2) in the water line

supplyigthe spray bar for the fist conveyor belt tranition and in the water lie supplyig the nozzles on the secondar conveyor transition The readings on thesemeters and gauges were obsered and recorded periodicaly thoughout both days of millig

Vehic1e speed and diection of trvel was meased using a Trible GeoXT hadheld data-loggig global positionig system (GPS) unt (Trible Navigation Ltd Sunyvale CA) receiver on the second day of millig The GPS unt was placed on padding on the top of the millig machie in an empty fi-extiguisher bracket (the extingusher had been relocated previously) in front of the operators station (Figue 3) Speed was also

4

observing and recording the foot speed reading on the intrent panel ofthe mil every two minutes As a measure recorded durng both days of miling by a NIOSH researcher

of productivity the time was recorded when each dump truck was loaded and pulled away from the millng machine

Depth of cut was measurecl every fifteen minutes during both milling days using a tape measure helcl at the edge of the cut pavement The width of the cut was measured as well Bulk samples of the miled pavement were collected on a periodic basis from

left in or next to the cut by the milling machine Wind speed and direction and temperature were recorded usigraveng a data-loggigraveug weather station (MultiLog Weather material

Station Fourier Systems Inc Atlanta GA) A hand-held muitigrave~directional impeller wind meter was also used during the survey (Skywatch Meteos JDC Electronic SA Yverdon-Ies-Bains Switzerland)

The work practices and use of personal protective equipment were recorded for each worker sampled including the workers position and distance relative to the miling machine (eg walking alongside following behind riding) Infomiation obtained from conversations with worlcers to detennine if the sampling days were typical of the nomial work load helped to place the sampling results in proper perspective Data were recorded describing other operations nearby that generated dust including the process its location relatIacuteve to the miling machine and whether it was upwind or downwind of the millng machine

Dust and Silca Sampling Methods

On both days of sampling personal breathing zone samples on the three members of the miling crew were collected at a flow rate of 42 liters per minute (Umin) using a battery-operated sampling pump at the employees waist connected via flexible tubing to a pre-weighed 37-mm diameter 5-micron (~m) pore-size polyvinyl chloride filter supported by a backup pad in a three-piece filter cassette sealed with a cellulose shrink band in accordance with NIOSH Methods 0600 and 7500 and a cyclone (GK 269 RespirableThoracic Cyclone BGi Inc Waltham MA) placed in the employees breathing zone (NIOSH 1994 HSE 1997)

Area samples were collected on both days of sampling at six locations on the millng instruments mounted on a metal frame (Figure 4) Themachine using an aray of

platform near the level controls onlocations included the dashboard on the operators

both sides of the mil near the cutter dr on both sides of the mil and on the right side

conveyor to the loading conveyor (Figure 5) The sampling intruments in each aray included a Ii ght-scattering aerosol photometer (pDR near the transition from the primary

Theano Electron Corp Franklin MA) with a 10 millmeter (mm) nylon cyclone comiected to the inlet via flexible tubing The pDR was in tur connected via flexible tubing to a battery-operated sampling pump calibrated at a flow rate of 17 Llmin A pre-weighed 5-~m pore-size polyvinyl chloride filter supported by a backup pad in a two-piece filter cassette sealed with a cellulose shr band was placed in line between the

5

pDR and the pump Also included in each sampling aray were two battery-operated sampling pumps both connected though flexible tubing to a 10-mm nylon cyclone and a pre-weighed 37-mm diameter 5-iexclm pore-size polyvnyl chloride filter supported by a backup pad in a two-piece filter cassette sealed with a cellulose shn band in accordance with NIOSH Methods 0600 and 7500

On the second day of sampling addigravetional area sauiples were collected at the six locations described above at a flow rate of 42 litersminute using a battery-operated sampling pump connected via flexible tubing to a pre-weighed 37-mm diameter 5shymicron (iexclm) pore-size polyvinyl chloride filter supported by a backup pad in a three-piece fiter cassette sealed with a cellulose shrink band in accordance with NIOSH Methods 0600 and 7500 and a cyclone (OK 269 RespirableThoracic Cyclone BGI Inc Waltham MA) attached to the metal frame

Gravimetric analysis for respirable pariculate was cared out with the fOllOWing modifications to NIOSH Method 0600 1) the fiters and backup pads were stored in an environmentally controlled room (201 1degC and 50i5 relative humidity) and were subj ected to the room conditions for at least two hours for stabilization prior to tare and gross weighing and 2) two weighings of the tare weight and gross weight were performed (NIOSH 1994) The difference between the average gross weight and the average tare weight was the result of the analysis The limit of detection for this method was 002 mg

Crystalline silica analysis ofthehigravegher-flow fiter and all bulk samples was perfornied using X-ray diffraction NIOSHMethod 7500 was used ith the following modifications 1) fiters were dissolved in tetraIgraveydrofurail rather than being ashed in a furace and 2) standards and samples were run concurently and an external calibration ciire was prepared from the integrated intensities rather than using the suggested normalization procedure (NIOSH 1994) These samples were analyzed for quarz and cristobalite The limits of detection for quarz and cristobalite on filters were 001 and 002 mg respectively The limit of quantiation is 003 mg for both quarz and cristobalite The lower-flow filter samples were not analyzed for silica

bulk samples collected from miled pavement left in or next to the cut by the millng machine The limit of detection for quar in bulk samples was 08 The limit of quantitation was 2

The silica content of the pavement was determined though testing of

Experimental design

Initial activities on site such as installing new water spray nozzles and new cutter-drm teeth were devoted to returing the mil to the manufacturers specifications DulIgraveng the

first day of sampling samples were collected over thee sampliacuteng periods during a typical miling job The second day of sampling was divided into four 2-hour periods During

the first period the manufacturer-specified nozzles (UniJetll model1 005 SS Spraying Systems Co Wheaton IL) rated at 05 gallons per minute (gpm) at 40 pounds per square

6

inch (psi) were used For the second and thd period higher-flow nozzles CUniJ etQI

model 11008 Spraying System Co Wheaton IL) rated at 08 gpm at 40 psi were installed on the cutter-dr spray bar Durng the final period the manufactuershy

specified nozzles were used again This design was used instead of a randomized design because of the length of time and effort required to change the nozzles in the field The spray nozzles for the primar conveyor and the material transfer conveyor were not changed Personal and high-flow area samples for respirable dust and respirable crystallne silica were changed approximately every two hours durig both sampling days The lower-flow area samples were collected for the full shift on both days

RESULTS AND DISCUSSION

Description of the Mil and the Controls

The miling machine used at this site had 3560 hours on the machine at the beginnng of the site visit It was equipped with water spray nozzles at three places including dr spraying nozzles primar conveyor spraying nozzles and material transfer conveying nozzles There were 18 flat fan spray nozzles (UniJetQI model 11005 SS Spraying Systems Co Wheaton IL) mounted on a spragravey bar in the cutter dru housing This type

of nozzle was used at all of the installations on this milL Thegrave fist thee nozzles on the cutter dr spray bar were mounted 2 inches (in) apar the thrd and fourh nozzle were

mounted 3 in apar and the remaining nozzles were 5 Yi in apar The cutter dr

extension was served by a separate spray bar equipped with thee nozzles The first two nozzles were 2in apar while the second and thrd nozzle were 5 Yi in apar There were a total of nine nozzles at the primary conveyor installed at the transition from the cutter dr to the primar conveyor four were mounted on each side and one on the extension

These nozzles were 1 foot apar There were two nozzles mounted above the material transfer conveyor at the transition from the primar cogravenveyor Those nozzles were 32 in apar New nozzles were installed on the evening before the first sampling day The water pump for the spraying system is rated at 40 Llmin (106 gallons) of water at 3 Yi bar (51 psi)

The 8 ft 6 in wide cutter dr held 193 bits aranged in a helical coil around the dr

holders were in factory spec condition with 50 hrs on the holders NewThe drm and

bits were installed on the evening before the first sampling day and were changed several times durg the next two days The dr rotation was measured and found to agree with

the manufacturers specification of928 rpm

Personal protective equipment and work practices

The miling crew members wore hard hats (except the operator) safety glasses and traffc safety vests The operator was the only employee who spent all of his time on the mil operating the mil from either the right or left side of the operators station The foreman spent the majority of the first day operatig the rear controls while the thid ecircrewman performed tasks such as operating a skid-steer loader and drvig the water

7

in the afternoon the foreman operated the skid steer loader while the third crewman ran the rear controls For the most par the skid-steer loader was not operated near the miling machine on the first day On one occasion a road grader passed by and for a brief period in the afternoon nugravellig took place alongside a field while a farer was running a combine On the second day the skid-steer loader

truck (Figure 6) However

the daythe day and the third crew member spent most ofwas idle for the majority of

the rear controls The foreman left the migravelperiodically to attend torunning one of

matters such as trck scheduling On both days the trcks assigned to take away thepossiblethe road unti that was no longermiled material drove on the paved portion of

lessening the potential of dust being generated by the trucks as they passed the millng machine

Respirable dust and crystallne silica sampling results

personal breathing zone sampling for respirable dust and crystalline silica conducted on October 8 are presented in Table 1 On October 8 which represented a typical millng day respirable dust results ranged from 014 to 183 mgm The TW A respirable dust exposures for the three employees were 026 mgmJ (499 minutes) for the

The results of

operator 10 mgm3 (495 minutes) for the foreman and 038 mgm3 (438 minutes) for the third employee who began the day operatin~ the skid steer loader Their 8-hour TWAs were 027 mgm3 for the operator 10 mgm for the foreman and 035 mgm3 for the third crew member The OSHA PELs for these employees calculated based upon the percent silica in their samples were 142 mgm 3 for the operator 117 mgm3 for the foreman and 113 mgm3 for the third member of the miling crew The PELs were calculated using the value of the LODJ for quarz values below the LOD (Hornung and Reed 1990) None of the employees exposures exceeded the OSHA PEL on October 8 as a TW A but excursions above the PEL did take place during the first two sampling periods for the foreman who spent most of those periods operating the rear controls on the mUL

Respirable quarz results from personal samples ranged from below the limit of to

detection 01 1 inglm3 The TW A respirable quarz exposures for October 8 were 0013 mgm3 for the operator 0064 mgm3 for the foreman and 0030 mgm3 for the third

LOD formiling Crew member The TWAs were also calculated using the value of

001 mg Their 8-hour quartz TWAs were 0014 mgm3 0066 mglm3 and 0027 mgm3 respectively On October 8 the foremans TWA and 8-hour TWA exposure exceeded the NIOSH quarz REL of 005 nigm3

quarz results less than the LOD of

the milling crews respirable dust and respirable quartzTable 2 lists the results of

exposures by nozzle type and employee results in TWAs of21 mgm3 for the operator 062 mgm3 for the foreman and 11 mgm3 for the rear control operator for the UniJ etfI 11005 nozzle versus 14 mglm3 065 mgm3 and 089 mgm respectively forthe UniJetaeligl 11008 nozzle TWA

samples on October 9 Calculating TWA respirable dust

the operator 0041

mgm3 for the foreman and 0050 mgin3 for the worker operating the rear controls quartz results for the UniJetfI 11005 nozzle were 012 mgm3 for

8

0081 mgm3 for the operator TW A quarz results for the UniacuteJetlIII008 nozzle were

0041 mgm3 for the foreman and 0043 mgm3 for the thrd crewman In contrast to October 8 the operator received the highest exposures on the second sampling day

Table 3 shows that the highest emissionsthe nozzle type Inspection ofregardless of

side of the mil and the upper conveyor Unfortunately the weather station did not log data so the effect of the wind direction on those results is unnown

were associated with the left

the area samplescoUected on October 8 with the lower-flow respirable dust samplers (17 Lmin) and the pdR direct-reading instruments Those results indicate that for both sampling methods that exposures were lowest igraven the

Table 4 reports the results of

operators station and highest at the upper conveyor (the material transfer conveyor) This table also lists the gravimetricpDR ratios calculated for each sampling location These ratios were used to adjust pDR short teimsampling concentrations which are provided later in ths report Table 5 presents the results for the lower-flow respirable

dust samples and the pdR samples for October 9 including the results from all nozzle types The upper conveyor produced the highest exposure on that day as welL Perhaps the operators personal exposures differ from the area sample at his work station because

the time on one or the other side of the mm while the sampler was in the

he spends most of

his work station (Figure 7) Table 5 which provides the results ofthe center of

lower-flow andpdR area samples shows that as in Table 3 the highest emissions were associated with the left side of the mill and the upper conveyor The migraveU removed

the road so the left side oftlie mm was facing the pavedmaterial from the right side of

the road while the right side faced the previous cut This orientation may explain the milL The manufacturers

edge of

in par why the exposures were higher on the left side of

6 relates area samplingrepresentative attributed this result to passing truck trame Table

results to productivity water flow and water spray pressure while Table 7 describes the work done on October 9

When reviewing the results of sampling conducted on October 9 for the purpose of this study it is useful to compare the results obtained when the different water spray nozzles

logwere used For the purpose ofthisaualysis the results were converted to the natural

the data did not vary with(In) scale because on the log scale the varabmty of

concentration From the In scale analysis of the respirable dust results (Tables 8~ II) the ratio of the UniJ etlf 11005 nozzle to the DniJ et(szlig i 1008 nozzle results is the ratio of their geometric means 12 This indicates that the respirable dust measurements obtained

are about 20 higher thotigh the result is not statistically significant even at the lO signifcance leveL Results for the pDRs are while the UniJetlf 11005 nozzle was used

also about 20 higher for the UnijetQ 11005 and are also notsimilar Those results are

statistically significant at the 10 leveL Examination oftbe tables indicates that for mostthe

groupings the UniJetlIl1005 nozzle does give higher results Review of all of

the UniacuteJet(( 11005 nozzle resultsrespirable dust data from October 9 shows that 59 of

exceeded the PEL while 50 of the UniJetI 11008 nozzle results did so For personal breathing zone samples half of the results while the Unijet(szlig 11005 was in use exceeded

the UnijetlI 11008 results exceeded the PELthe PEL one third of

9

From the In scale analysis of the quarz samplig results (Tables 12-15) the ratio of the Uniet(szlig 11005 nozzle to the Uniet(szlig 11008 nozzle results is the ratio of their geometrc means 116 Thus for respirable quar the results while Uniet(szlig i 1005 nozzles were intalled on the cutter drm were about 16 higher though the result is not statisticaly signficant even at the 10 signcance leveL Examation of the tables indicates that the quar results are not as consistent as those for respirable dust For data from both days 7 respirable quar results were less than the LOD and 13 values were between LOD and LOQ For the seven quarz values below the LOD the value Lan was substituted

Quarz in bulk samples

The results of 10 bulk samples ranged from 12 to 28 with a mean of 199 and a median of 185

CONCLUSIONS AN RECOMMNDATIONS

Conclusions from ths pilot study regardig the effect of increasing the water flow to the spray nozzles on dust and quart exposures are lited by several factors First the higher flow nozzles were only intalled on the cutter dr and the cutter dr extension

the nozzles selected represent a difference of only 30 more flow when the higher-flow nozzles were installed Nevereless the respirable dust measurements obtaied while the Uniet(szlig 11005 nozzles were used were about 20 higher than when the higher-flow Uniet(szlig 11008 nozzles were used The respirable quarz results while Uniet(szlig 11005 nozzles were installed on the cutter dr were about 16 higher Neither

Second

the reductions in respirable dust concentrations nor those for the quarz results were statistically signficant even at the lO signficance leveL Statistical signficance mean that the difference is not due to chance alone

Research on dust controls in minig has shown that water sprays have two roles wetting of broken material being transported and airborne captue (NOSH 2003) Uniformly wetting the broken material durg the breakage process is far more effective and enures that dust paricles stay attached to the materal (NQSH 2003) Increasing the water flow rate and increasing the number of sprays have both been shown to be effective it is tooearly in this proj ect to recommend an approach In one inance dust from a shearer dr was reduced by 60 when the 46 smaler orifice nozzles were substituted for the originall7 nozzles with the pressure and flow held constant (NOSH 2003) The shape of the spray is another importnt factor in its effectveness

Futue studies might test the water system on a newer-model machie to begi to explore the relationship between water flow and pressue agravend aiborne dust concentrtions Varables related to the site andjob might obscure ths relationship but it is hoped that a trend might emerge

10

REFERENCES

29 CFR 19101000 (2001) Occupational Safety and Health Admstration air

containants

29 CFR 192655 (2003) Occupational Safety and Health Adminstration gases vapors fues dusts and mists

ACGrn (2004) Theshold limit values for chemical substances CincinatiOH American Conference of Governental Industral Hygienists

Akbar-Khanadeh F Brillhar RL (2002) Respirable crystallne silca dust exposure durng concrete finshing (grnding) using hand-held grnders in the constrction industr An occup Hyg 46341-346

Bureau of Mines (1992) Crystallne silica primer Washigton DC US Deparent of the Interior Bureau of Mines Branch of Industral Minerals Special Publication

Glindmeyer HW Hamad YY (1988) Contributing factors to sandblasters silcosis inadequate respiratory protection equipment and standards J accup Med 30917-921

HSE (1997) MDHS 142 General methods for sampling and gravimetrc analysis of respirable and total inhalable dust Methods for the determination of hazardous substances lIealth and safety laboratory Sudbur Suffolk UK Health and Safety Executive

Homuug R Reed L (1990) Estimation of average concentration in the presence of nondetectable values Applied Occupational and Environmental Hygiene 5(1)46-51

Linch KD (2002) Respirable concrete dust-silcosis hazard in the constrction industr

Appl Occup and Environ Hyg 17 209-221

Neuhauser Curt (curneuhauser(ecircdotstatewius) (2004) RE US 12 project Private e-mail message to Alan Echt (AEcht(ecirccdcgov) Januar 7

New Jersey Deparent of Health and Senior Services (2001) New Jersey silica parership In Occupational Health Sureilance Update February Trenton NJ NJ

Deparment of Health and Senior Services Division of Epidemiology Environmental and Occupational Health Occupational Health Service Occupational Health Sureilance Program

11

INTRODUCTION

The National Institute for Occupational Safety and Health (NOSH) is located in the Centers for Disease Control and Prevention (CDe) par of the Deparent of Health and Human Services (DHHS) NIOSH was established in 1970 by the Occupational Safety and Health Act at the same time that the Occupational Safety and Health Adminstration

Labor (DOL) The OSH Act legislation mandated NIOSH to conduct research and education programs separate from the standard-setting and enforcement fuctions conducted by OSHA An important area of NIaSH research deals with methods for controllng occupational exposure to potential chemical and physical hazards

(OSHA) was established in the Deparent of

The Engineering and Physical Hazards Branch (EPHB) of the Division of Applied Research and Technology (DART) has been given the lead within NIOSH to study and develop engineering controls and assess their impact on reducing occupational ilness Since 1976 EPHB (and its predecessor the Engineering Control Technology Branch) has conducted a large number of studies to evaluate engineerig control technology based upon industr process or control technique The objective of each ofthese studies has

been to evaluate and document control techniques and to determine their effectiveness in reducing potential health hazards in an industr or for a specific process

The primary aim of this project is to determine if the engineering controls supplied with new miling machines and operated according to the manufactuers recommendations are adequate to control worker exposures to respirable dust and respirable crystallne silca (in the fonI of quarz) The long term goal of ths project is to reduce worker exposures to silica hy providing data to support the development of a set of practice guidelines for the equipment if the engineering controls are adequate or to develop a set

best

of recommendations to improve the performance of controls if they are not adequate

Many constrction tasks have been associated with overexposure to crystalline silca (Rappaport et al 2003) Among these tasks are tuck pointing concrete sawing concrete grding and abrasive blasting (NIOSH 2000 Thorpe et aL 1999 Akbar-Kanadeh andBrillhar 2002 Glindmeyer and Hamad 1988) Road miling has also been shown to result in overexposures to respirable crystallne silca (Linch 2002 Rappaport et aL 2003 NJ Dept of Health and Senior Services 2001) However all three of the road-miling studies are limited because they do not provide enough information about the operating parameters and engineering controls present on the miling machies to determine if the overexposures were due to a lack of effective controls or poor work practices This study wil attempt to fill that knowledge gap

A varety of machinery and work practices are employed in asphalt pavement recycling includng cold-planers heater planers cold-millers and heater-scarfiers (public Works 1995) Cold-millng which uses a toothed rotating dr to grind and remove the

1

pavement to be recycled is primarily used to remove surface deterioration on both asphalt and Portland cement concrete road surfaces (public Works 1995) The millng machines used in cold miling are the fociis ofthis investigation

the US 12The cold miling work observed durng ths piacutelot study was par of

section ofreconstruction project from CTH KP to STH 19 west in Wisconsin This was a

old US 12 that was rehabiltated and wil be tranferred to the local township There was a 20 ft wide concrete pavement placed in the early 1900s Above that was a layer of

varying thickness about 0 inches to 10 inches Above that was varying asphaIgravet pavement thiclmess of about 8 to more than 12 inches which had crushed aggregate base course of

been placed at varous times in about the last 60 years The asphaltic pavement was rutted and cracked to varying degrees The portion of old US 12 from Simpson Road to the south where it meets the new US 12 was re-graded on new alignent this pavement removal was specified by a Common Excavation item The Common Excavation item specification enables the contractor to remove the pavement in any way they see fit In this case the contractor chose to mill the pavement because it was of value

removed and disposed of In the area from Simpson to the nort this section was not re-graded but the entigravere existing asphaltic pavement was removed under the item of Removing Asphaltic Surface This specifies the removal of only the asphaltic pavement Again the contractor chose

as a recycled product The existing concrete was also

and recycle it (Neuhauser 2004)to salvage this pavement

This study was faciltated by a partership in cooperation with the National Asphalt Pavement Assocation that includes millng machine manufacturers contractors employee

the millng machinerepresentatives NIOSH and other interested paries One of

study on a 2003 miacuteling machine model with the latest state-of-the-ar water spraying system produced by the manufacturer The mill is a half-lane miling machine rated at 560HP with a water spray system capable of l5gpm at 200psI This system was put into production in 2001 - before initial discussions on testing airborne dust concentration

manufacturers manufacturer A had initially arranged to perform the pilot

About one week before the pilot study was to be performed manufacturer A leared that the 2003 mil would not be available for the test Instead an older machine was substituted The replacement machine was a half-lane millng machine rated at 800 HP with an eight-foot cutter and an older model water system designed for i Ogpm at 50psi

Manufacturer A knew that the lower water flow at much lower pressure would result in higher airborne dust content hut Manufacturer A was stil confident that the dust suppression system even on the older model machines should still be very effective if properly maintained and operated Therefore Manufacturer A agreed to perform the test (even with the last minute changes) as a means of getting at least a good baseline for this type of airborne dust test

2

OCCUPATIONAL EXPOSUR TO CRYSTALLIN SILICA

Silcosis is an occupational respiratory disease caused by inaling respirable crystalline

silca dust Silcosis is irreversible often progressive (even after exposure has ceased)

and potentially fataL Because no effective treatment exists for silicosis prevention though exposure control is essentiaL Exposure to respirable crystalline silca dust occurs in many occupations including constrction Crystalline silca refers to a group of minerals composed of silcon and oxygen a crystalline strctue is one in which the atoms are aranged in a repeating three-dimensional pattern (Bureau of Mines 1992) The three major forms of crystalline silca are quartz cristobalite and trdymite quar is the most common form (Bureau of Mines 1992) Respirable refers to that portion of airborne crystalline silca that is capable of entering the gas-exchange regions of the lungs if inhaled this includes paricles with aerodynamc diameters less than approximately 10

Ilm (NOSH 2002)

When proper practices are not followed or controls are not maintained respirable crystallne silica exposures can exceed the NIaSH Recommended Exposure Limit

Permssible Exposure Limit (PEL) or the American Conference of(RL) the OSHA

Governental Industral Hygienists (ACGIH) Threshold Limit Value (TLV) (NOSH 200229 CFR 19101000 ACGll 2004) NiaSH recommends an exposure limit of 005 mgm3 to reduce the risk of developing silicosis lung cancer and other adverse health effects

The OSHA PEL for respirable dust containing 1 quarz or more in general industr is expressed as an equation (29 CFR 19101000)

10 mgm3 Respirable PEL =

Silca + 2

If for example the dust contai no crystalline silica the PEL is 5 mgm3 and if the dust is 100 crystalline silca the PEL is 01 mgm3 For trdymite and cristobalite OSHA uses half the value calculated using the formula for quarz (29 CPR 19101000)

The curent OSHA permissible exposure limit (PEL) for respirable dust containng crystallne silica (quartz) for the constrction industr is measured by impinger sampling The PEL is expressed in millons of paricles per cubic foot (mppcf) and is calculated using the following formula (29 CFR 192655)

250 mppcf Respirable PEL =

Silca + 5

3

Since the PELs were adopted the impinger sampling method ha been rendered obsolete by gravimetrc sampling (OSHA 1996) OSHA is not aware of any goverent agencies or employers in ths countr that are curently usng impinger sampling to assess worker

exposure to dust containig crystallne silca and impinger samples are generally

recogned as being less reliable than gravimetrc samples (OSHA 1996) OSHA has determed that sampling procedures in the consction industr should be the same as in general industr and that the mppcfPEL in 29 CFR 192655(a) is equivalent to the mgm3 PEL in 29 CFR 19101000 (aSHA 1996)

The ACGrnCE TL VIs for cristobalte quar and trdymte are all 005 mglm3 (ACGm 2004) The ACGrn~ ha published a notice of their intent to change the TL ~ for (Xshyquar and cristobalte (respirable fraction) to 0025 mgm3 and to withdraw the documentation and adopted TL yi for trdymte (ACGrn 2004)

METHODS

Descriptive data about the millig machie were gathered durng the aferoon and evening prior to the fist day of sampling while the machie was undergoing repais at the Payne amp Dolan shop Information was collected about the number tye condition and placement of water spray nozzles on thedr and at the conveyor belt tranitions the cutter dr rotation rate (measured using a non-contact tachometer (T AC2K Dwyer Instrents Inc Michigan City Indiana) while the mill was rug) the hours on the machie the cutter dr condition and the cutter bits including their spacing condition make and model number NIOSH personnel worked with Payne amp Dolan sta and the manufactuers representative to install water flow meters and pressure gauges install new water spray nozzles and cutter bits and restore the water spray nozzles at the seconda conveyor tranition to the manufactuers specification This tie was also used to lear aboutthe operation of the machie and safe work practices

Water flow rate was measured using two water flow meters (Confowmeter II Confow Inc WashigtonP A) intaled in the water supply lies on the milL One meter was installed in the line between the water pump and the cutter dr spray bar The second meter was installed in the line between the water pump and the conveyor transition sprays (Figure 1 ) Water pressure was measured using pressure gauges attched to tee-fittgs

instaled in the water lie supplyig the cutter dr spray bar (Figue 2) in the water line

supplyigthe spray bar for the fist conveyor belt tranition and in the water lie supplyig the nozzles on the secondar conveyor transition The readings on thesemeters and gauges were obsered and recorded periodicaly thoughout both days of millig

Vehic1e speed and diection of trvel was meased using a Trible GeoXT hadheld data-loggig global positionig system (GPS) unt (Trible Navigation Ltd Sunyvale CA) receiver on the second day of millig The GPS unt was placed on padding on the top of the millig machie in an empty fi-extiguisher bracket (the extingusher had been relocated previously) in front of the operators station (Figue 3) Speed was also

4

observing and recording the foot speed reading on the intrent panel ofthe mil every two minutes As a measure recorded durng both days of miling by a NIOSH researcher

of productivity the time was recorded when each dump truck was loaded and pulled away from the millng machine

Depth of cut was measurecl every fifteen minutes during both milling days using a tape measure helcl at the edge of the cut pavement The width of the cut was measured as well Bulk samples of the miled pavement were collected on a periodic basis from

left in or next to the cut by the milling machine Wind speed and direction and temperature were recorded usigraveng a data-loggigraveug weather station (MultiLog Weather material

Station Fourier Systems Inc Atlanta GA) A hand-held muitigrave~directional impeller wind meter was also used during the survey (Skywatch Meteos JDC Electronic SA Yverdon-Ies-Bains Switzerland)

The work practices and use of personal protective equipment were recorded for each worker sampled including the workers position and distance relative to the miling machine (eg walking alongside following behind riding) Infomiation obtained from conversations with worlcers to detennine if the sampling days were typical of the nomial work load helped to place the sampling results in proper perspective Data were recorded describing other operations nearby that generated dust including the process its location relatIacuteve to the miling machine and whether it was upwind or downwind of the millng machine

Dust and Silca Sampling Methods

On both days of sampling personal breathing zone samples on the three members of the miling crew were collected at a flow rate of 42 liters per minute (Umin) using a battery-operated sampling pump at the employees waist connected via flexible tubing to a pre-weighed 37-mm diameter 5-micron (~m) pore-size polyvinyl chloride filter supported by a backup pad in a three-piece filter cassette sealed with a cellulose shrink band in accordance with NIOSH Methods 0600 and 7500 and a cyclone (GK 269 RespirableThoracic Cyclone BGi Inc Waltham MA) placed in the employees breathing zone (NIOSH 1994 HSE 1997)

Area samples were collected on both days of sampling at six locations on the millng instruments mounted on a metal frame (Figure 4) Themachine using an aray of

platform near the level controls onlocations included the dashboard on the operators

both sides of the mil near the cutter dr on both sides of the mil and on the right side

conveyor to the loading conveyor (Figure 5) The sampling intruments in each aray included a Ii ght-scattering aerosol photometer (pDR near the transition from the primary

Theano Electron Corp Franklin MA) with a 10 millmeter (mm) nylon cyclone comiected to the inlet via flexible tubing The pDR was in tur connected via flexible tubing to a battery-operated sampling pump calibrated at a flow rate of 17 Llmin A pre-weighed 5-~m pore-size polyvinyl chloride filter supported by a backup pad in a two-piece filter cassette sealed with a cellulose shr band was placed in line between the

5

pDR and the pump Also included in each sampling aray were two battery-operated sampling pumps both connected though flexible tubing to a 10-mm nylon cyclone and a pre-weighed 37-mm diameter 5-iexclm pore-size polyvnyl chloride filter supported by a backup pad in a two-piece filter cassette sealed with a cellulose shn band in accordance with NIOSH Methods 0600 and 7500

On the second day of sampling addigravetional area sauiples were collected at the six locations described above at a flow rate of 42 litersminute using a battery-operated sampling pump connected via flexible tubing to a pre-weighed 37-mm diameter 5shymicron (iexclm) pore-size polyvinyl chloride filter supported by a backup pad in a three-piece fiter cassette sealed with a cellulose shrink band in accordance with NIOSH Methods 0600 and 7500 and a cyclone (OK 269 RespirableThoracic Cyclone BGI Inc Waltham MA) attached to the metal frame

Gravimetric analysis for respirable pariculate was cared out with the fOllOWing modifications to NIOSH Method 0600 1) the fiters and backup pads were stored in an environmentally controlled room (201 1degC and 50i5 relative humidity) and were subj ected to the room conditions for at least two hours for stabilization prior to tare and gross weighing and 2) two weighings of the tare weight and gross weight were performed (NIOSH 1994) The difference between the average gross weight and the average tare weight was the result of the analysis The limit of detection for this method was 002 mg

Crystalline silica analysis ofthehigravegher-flow fiter and all bulk samples was perfornied using X-ray diffraction NIOSHMethod 7500 was used ith the following modifications 1) fiters were dissolved in tetraIgraveydrofurail rather than being ashed in a furace and 2) standards and samples were run concurently and an external calibration ciire was prepared from the integrated intensities rather than using the suggested normalization procedure (NIOSH 1994) These samples were analyzed for quarz and cristobalite The limits of detection for quarz and cristobalite on filters were 001 and 002 mg respectively The limit of quantiation is 003 mg for both quarz and cristobalite The lower-flow filter samples were not analyzed for silica

bulk samples collected from miled pavement left in or next to the cut by the millng machine The limit of detection for quar in bulk samples was 08 The limit of quantitation was 2

The silica content of the pavement was determined though testing of

Experimental design

Initial activities on site such as installing new water spray nozzles and new cutter-drm teeth were devoted to returing the mil to the manufacturers specifications DulIgraveng the

first day of sampling samples were collected over thee sampliacuteng periods during a typical miling job The second day of sampling was divided into four 2-hour periods During

the first period the manufacturer-specified nozzles (UniJetll model1 005 SS Spraying Systems Co Wheaton IL) rated at 05 gallons per minute (gpm) at 40 pounds per square

6

inch (psi) were used For the second and thd period higher-flow nozzles CUniJ etQI

model 11008 Spraying System Co Wheaton IL) rated at 08 gpm at 40 psi were installed on the cutter-dr spray bar Durng the final period the manufactuershy

specified nozzles were used again This design was used instead of a randomized design because of the length of time and effort required to change the nozzles in the field The spray nozzles for the primar conveyor and the material transfer conveyor were not changed Personal and high-flow area samples for respirable dust and respirable crystallne silica were changed approximately every two hours durig both sampling days The lower-flow area samples were collected for the full shift on both days

RESULTS AND DISCUSSION

Description of the Mil and the Controls

The miling machine used at this site had 3560 hours on the machine at the beginnng of the site visit It was equipped with water spray nozzles at three places including dr spraying nozzles primar conveyor spraying nozzles and material transfer conveying nozzles There were 18 flat fan spray nozzles (UniJetQI model 11005 SS Spraying Systems Co Wheaton IL) mounted on a spragravey bar in the cutter dru housing This type

of nozzle was used at all of the installations on this milL Thegrave fist thee nozzles on the cutter dr spray bar were mounted 2 inches (in) apar the thrd and fourh nozzle were

mounted 3 in apar and the remaining nozzles were 5 Yi in apar The cutter dr

extension was served by a separate spray bar equipped with thee nozzles The first two nozzles were 2in apar while the second and thrd nozzle were 5 Yi in apar There were a total of nine nozzles at the primary conveyor installed at the transition from the cutter dr to the primar conveyor four were mounted on each side and one on the extension

These nozzles were 1 foot apar There were two nozzles mounted above the material transfer conveyor at the transition from the primar cogravenveyor Those nozzles were 32 in apar New nozzles were installed on the evening before the first sampling day The water pump for the spraying system is rated at 40 Llmin (106 gallons) of water at 3 Yi bar (51 psi)

The 8 ft 6 in wide cutter dr held 193 bits aranged in a helical coil around the dr

holders were in factory spec condition with 50 hrs on the holders NewThe drm and

bits were installed on the evening before the first sampling day and were changed several times durg the next two days The dr rotation was measured and found to agree with

the manufacturers specification of928 rpm

Personal protective equipment and work practices

The miling crew members wore hard hats (except the operator) safety glasses and traffc safety vests The operator was the only employee who spent all of his time on the mil operating the mil from either the right or left side of the operators station The foreman spent the majority of the first day operatig the rear controls while the thid ecircrewman performed tasks such as operating a skid-steer loader and drvig the water

7

in the afternoon the foreman operated the skid steer loader while the third crewman ran the rear controls For the most par the skid-steer loader was not operated near the miling machine on the first day On one occasion a road grader passed by and for a brief period in the afternoon nugravellig took place alongside a field while a farer was running a combine On the second day the skid-steer loader

truck (Figure 6) However

the daythe day and the third crew member spent most ofwas idle for the majority of

the rear controls The foreman left the migravelperiodically to attend torunning one of

matters such as trck scheduling On both days the trcks assigned to take away thepossiblethe road unti that was no longermiled material drove on the paved portion of

lessening the potential of dust being generated by the trucks as they passed the millng machine

Respirable dust and crystallne silica sampling results

personal breathing zone sampling for respirable dust and crystalline silica conducted on October 8 are presented in Table 1 On October 8 which represented a typical millng day respirable dust results ranged from 014 to 183 mgm The TW A respirable dust exposures for the three employees were 026 mgmJ (499 minutes) for the

The results of

operator 10 mgm3 (495 minutes) for the foreman and 038 mgm3 (438 minutes) for the third employee who began the day operatin~ the skid steer loader Their 8-hour TWAs were 027 mgm3 for the operator 10 mgm for the foreman and 035 mgm3 for the third crew member The OSHA PELs for these employees calculated based upon the percent silica in their samples were 142 mgm 3 for the operator 117 mgm3 for the foreman and 113 mgm3 for the third member of the miling crew The PELs were calculated using the value of the LODJ for quarz values below the LOD (Hornung and Reed 1990) None of the employees exposures exceeded the OSHA PEL on October 8 as a TW A but excursions above the PEL did take place during the first two sampling periods for the foreman who spent most of those periods operating the rear controls on the mUL

Respirable quarz results from personal samples ranged from below the limit of to

detection 01 1 inglm3 The TW A respirable quarz exposures for October 8 were 0013 mgm3 for the operator 0064 mgm3 for the foreman and 0030 mgm3 for the third

LOD formiling Crew member The TWAs were also calculated using the value of

001 mg Their 8-hour quartz TWAs were 0014 mgm3 0066 mglm3 and 0027 mgm3 respectively On October 8 the foremans TWA and 8-hour TWA exposure exceeded the NIOSH quarz REL of 005 nigm3

quarz results less than the LOD of

the milling crews respirable dust and respirable quartzTable 2 lists the results of

exposures by nozzle type and employee results in TWAs of21 mgm3 for the operator 062 mgm3 for the foreman and 11 mgm3 for the rear control operator for the UniJ etfI 11005 nozzle versus 14 mglm3 065 mgm3 and 089 mgm respectively forthe UniJetaeligl 11008 nozzle TWA

samples on October 9 Calculating TWA respirable dust

the operator 0041

mgm3 for the foreman and 0050 mgin3 for the worker operating the rear controls quartz results for the UniJetfI 11005 nozzle were 012 mgm3 for

8

0081 mgm3 for the operator TW A quarz results for the UniacuteJetlIII008 nozzle were

0041 mgm3 for the foreman and 0043 mgm3 for the thrd crewman In contrast to October 8 the operator received the highest exposures on the second sampling day

Table 3 shows that the highest emissionsthe nozzle type Inspection ofregardless of

side of the mil and the upper conveyor Unfortunately the weather station did not log data so the effect of the wind direction on those results is unnown

were associated with the left

the area samplescoUected on October 8 with the lower-flow respirable dust samplers (17 Lmin) and the pdR direct-reading instruments Those results indicate that for both sampling methods that exposures were lowest igraven the

Table 4 reports the results of

operators station and highest at the upper conveyor (the material transfer conveyor) This table also lists the gravimetricpDR ratios calculated for each sampling location These ratios were used to adjust pDR short teimsampling concentrations which are provided later in ths report Table 5 presents the results for the lower-flow respirable

dust samples and the pdR samples for October 9 including the results from all nozzle types The upper conveyor produced the highest exposure on that day as welL Perhaps the operators personal exposures differ from the area sample at his work station because

the time on one or the other side of the mm while the sampler was in the

he spends most of

his work station (Figure 7) Table 5 which provides the results ofthe center of

lower-flow andpdR area samples shows that as in Table 3 the highest emissions were associated with the left side of the mill and the upper conveyor The migraveU removed

the road so the left side oftlie mm was facing the pavedmaterial from the right side of

the road while the right side faced the previous cut This orientation may explain the milL The manufacturers

edge of

in par why the exposures were higher on the left side of

6 relates area samplingrepresentative attributed this result to passing truck trame Table

results to productivity water flow and water spray pressure while Table 7 describes the work done on October 9

When reviewing the results of sampling conducted on October 9 for the purpose of this study it is useful to compare the results obtained when the different water spray nozzles

logwere used For the purpose ofthisaualysis the results were converted to the natural

the data did not vary with(In) scale because on the log scale the varabmty of

concentration From the In scale analysis of the respirable dust results (Tables 8~ II) the ratio of the UniJ etlf 11005 nozzle to the DniJ et(szlig i 1008 nozzle results is the ratio of their geometric means 12 This indicates that the respirable dust measurements obtained

are about 20 higher thotigh the result is not statistically significant even at the lO signifcance leveL Results for the pDRs are while the UniJetlf 11005 nozzle was used

also about 20 higher for the UnijetQ 11005 and are also notsimilar Those results are

statistically significant at the 10 leveL Examination oftbe tables indicates that for mostthe

groupings the UniJetlIl1005 nozzle does give higher results Review of all of

the UniacuteJet(( 11005 nozzle resultsrespirable dust data from October 9 shows that 59 of

exceeded the PEL while 50 of the UniJetI 11008 nozzle results did so For personal breathing zone samples half of the results while the Unijet(szlig 11005 was in use exceeded

the UnijetlI 11008 results exceeded the PELthe PEL one third of

9

From the In scale analysis of the quarz samplig results (Tables 12-15) the ratio of the Uniet(szlig 11005 nozzle to the Uniet(szlig 11008 nozzle results is the ratio of their geometrc means 116 Thus for respirable quar the results while Uniet(szlig i 1005 nozzles were intalled on the cutter drm were about 16 higher though the result is not statisticaly signficant even at the 10 signcance leveL Examation of the tables indicates that the quar results are not as consistent as those for respirable dust For data from both days 7 respirable quar results were less than the LOD and 13 values were between LOD and LOQ For the seven quarz values below the LOD the value Lan was substituted

Quarz in bulk samples

The results of 10 bulk samples ranged from 12 to 28 with a mean of 199 and a median of 185

CONCLUSIONS AN RECOMMNDATIONS

Conclusions from ths pilot study regardig the effect of increasing the water flow to the spray nozzles on dust and quart exposures are lited by several factors First the higher flow nozzles were only intalled on the cutter dr and the cutter dr extension

the nozzles selected represent a difference of only 30 more flow when the higher-flow nozzles were installed Nevereless the respirable dust measurements obtaied while the Uniet(szlig 11005 nozzles were used were about 20 higher than when the higher-flow Uniet(szlig 11008 nozzles were used The respirable quarz results while Uniet(szlig 11005 nozzles were installed on the cutter dr were about 16 higher Neither

Second

the reductions in respirable dust concentrations nor those for the quarz results were statistically signficant even at the lO signficance leveL Statistical signficance mean that the difference is not due to chance alone

Research on dust controls in minig has shown that water sprays have two roles wetting of broken material being transported and airborne captue (NOSH 2003) Uniformly wetting the broken material durg the breakage process is far more effective and enures that dust paricles stay attached to the materal (NQSH 2003) Increasing the water flow rate and increasing the number of sprays have both been shown to be effective it is tooearly in this proj ect to recommend an approach In one inance dust from a shearer dr was reduced by 60 when the 46 smaler orifice nozzles were substituted for the originall7 nozzles with the pressure and flow held constant (NOSH 2003) The shape of the spray is another importnt factor in its effectveness

Futue studies might test the water system on a newer-model machie to begi to explore the relationship between water flow and pressue agravend aiborne dust concentrtions Varables related to the site andjob might obscure ths relationship but it is hoped that a trend might emerge

10

REFERENCES

29 CFR 19101000 (2001) Occupational Safety and Health Admstration air

containants

29 CFR 192655 (2003) Occupational Safety and Health Adminstration gases vapors fues dusts and mists

ACGrn (2004) Theshold limit values for chemical substances CincinatiOH American Conference of Governental Industral Hygienists

Akbar-Khanadeh F Brillhar RL (2002) Respirable crystallne silca dust exposure durng concrete finshing (grnding) using hand-held grnders in the constrction industr An occup Hyg 46341-346

Bureau of Mines (1992) Crystallne silica primer Washigton DC US Deparent of the Interior Bureau of Mines Branch of Industral Minerals Special Publication

Glindmeyer HW Hamad YY (1988) Contributing factors to sandblasters silcosis inadequate respiratory protection equipment and standards J accup Med 30917-921

HSE (1997) MDHS 142 General methods for sampling and gravimetrc analysis of respirable and total inhalable dust Methods for the determination of hazardous substances lIealth and safety laboratory Sudbur Suffolk UK Health and Safety Executive

Homuug R Reed L (1990) Estimation of average concentration in the presence of nondetectable values Applied Occupational and Environmental Hygiene 5(1)46-51

Linch KD (2002) Respirable concrete dust-silcosis hazard in the constrction industr

Appl Occup and Environ Hyg 17 209-221

Neuhauser Curt (curneuhauser(ecircdotstatewius) (2004) RE US 12 project Private e-mail message to Alan Echt (AEcht(ecirccdcgov) Januar 7

New Jersey Deparent of Health and Senior Services (2001) New Jersey silica parership In Occupational Health Sureilance Update February Trenton NJ NJ

Deparment of Health and Senior Services Division of Epidemiology Environmental and Occupational Health Occupational Health Service Occupational Health Sureilance Program

11

pavement to be recycled is primarily used to remove surface deterioration on both asphalt and Portland cement concrete road surfaces (public Works 1995) The millng machines used in cold miling are the fociis ofthis investigation

the US 12The cold miling work observed durng ths piacutelot study was par of

section ofreconstruction project from CTH KP to STH 19 west in Wisconsin This was a

old US 12 that was rehabiltated and wil be tranferred to the local township There was a 20 ft wide concrete pavement placed in the early 1900s Above that was a layer of

varying thickness about 0 inches to 10 inches Above that was varying asphaIgravet pavement thiclmess of about 8 to more than 12 inches which had crushed aggregate base course of

been placed at varous times in about the last 60 years The asphaltic pavement was rutted and cracked to varying degrees The portion of old US 12 from Simpson Road to the south where it meets the new US 12 was re-graded on new alignent this pavement removal was specified by a Common Excavation item The Common Excavation item specification enables the contractor to remove the pavement in any way they see fit In this case the contractor chose to mill the pavement because it was of value

removed and disposed of In the area from Simpson to the nort this section was not re-graded but the entigravere existing asphaltic pavement was removed under the item of Removing Asphaltic Surface This specifies the removal of only the asphaltic pavement Again the contractor chose

as a recycled product The existing concrete was also

and recycle it (Neuhauser 2004)to salvage this pavement

This study was faciltated by a partership in cooperation with the National Asphalt Pavement Assocation that includes millng machine manufacturers contractors employee

the millng machinerepresentatives NIOSH and other interested paries One of

study on a 2003 miacuteling machine model with the latest state-of-the-ar water spraying system produced by the manufacturer The mill is a half-lane miling machine rated at 560HP with a water spray system capable of l5gpm at 200psI This system was put into production in 2001 - before initial discussions on testing airborne dust concentration

manufacturers manufacturer A had initially arranged to perform the pilot

About one week before the pilot study was to be performed manufacturer A leared that the 2003 mil would not be available for the test Instead an older machine was substituted The replacement machine was a half-lane millng machine rated at 800 HP with an eight-foot cutter and an older model water system designed for i Ogpm at 50psi

Manufacturer A knew that the lower water flow at much lower pressure would result in higher airborne dust content hut Manufacturer A was stil confident that the dust suppression system even on the older model machines should still be very effective if properly maintained and operated Therefore Manufacturer A agreed to perform the test (even with the last minute changes) as a means of getting at least a good baseline for this type of airborne dust test

2

OCCUPATIONAL EXPOSUR TO CRYSTALLIN SILICA

Silcosis is an occupational respiratory disease caused by inaling respirable crystalline

silca dust Silcosis is irreversible often progressive (even after exposure has ceased)

and potentially fataL Because no effective treatment exists for silicosis prevention though exposure control is essentiaL Exposure to respirable crystalline silca dust occurs in many occupations including constrction Crystalline silca refers to a group of minerals composed of silcon and oxygen a crystalline strctue is one in which the atoms are aranged in a repeating three-dimensional pattern (Bureau of Mines 1992) The three major forms of crystalline silca are quartz cristobalite and trdymite quar is the most common form (Bureau of Mines 1992) Respirable refers to that portion of airborne crystalline silca that is capable of entering the gas-exchange regions of the lungs if inhaled this includes paricles with aerodynamc diameters less than approximately 10

Ilm (NOSH 2002)

When proper practices are not followed or controls are not maintained respirable crystallne silica exposures can exceed the NIaSH Recommended Exposure Limit

Permssible Exposure Limit (PEL) or the American Conference of(RL) the OSHA

Governental Industral Hygienists (ACGIH) Threshold Limit Value (TLV) (NOSH 200229 CFR 19101000 ACGll 2004) NiaSH recommends an exposure limit of 005 mgm3 to reduce the risk of developing silicosis lung cancer and other adverse health effects

The OSHA PEL for respirable dust containing 1 quarz or more in general industr is expressed as an equation (29 CFR 19101000)

10 mgm3 Respirable PEL =

Silca + 2

If for example the dust contai no crystalline silica the PEL is 5 mgm3 and if the dust is 100 crystalline silca the PEL is 01 mgm3 For trdymite and cristobalite OSHA uses half the value calculated using the formula for quarz (29 CPR 19101000)

The curent OSHA permissible exposure limit (PEL) for respirable dust containng crystallne silica (quartz) for the constrction industr is measured by impinger sampling The PEL is expressed in millons of paricles per cubic foot (mppcf) and is calculated using the following formula (29 CFR 192655)

250 mppcf Respirable PEL =

Silca + 5

3

Since the PELs were adopted the impinger sampling method ha been rendered obsolete by gravimetrc sampling (OSHA 1996) OSHA is not aware of any goverent agencies or employers in ths countr that are curently usng impinger sampling to assess worker

exposure to dust containig crystallne silca and impinger samples are generally

recogned as being less reliable than gravimetrc samples (OSHA 1996) OSHA has determed that sampling procedures in the consction industr should be the same as in general industr and that the mppcfPEL in 29 CFR 192655(a) is equivalent to the mgm3 PEL in 29 CFR 19101000 (aSHA 1996)

The ACGrnCE TL VIs for cristobalte quar and trdymte are all 005 mglm3 (ACGm 2004) The ACGrn~ ha published a notice of their intent to change the TL ~ for (Xshyquar and cristobalte (respirable fraction) to 0025 mgm3 and to withdraw the documentation and adopted TL yi for trdymte (ACGrn 2004)

METHODS

Descriptive data about the millig machie were gathered durng the aferoon and evening prior to the fist day of sampling while the machie was undergoing repais at the Payne amp Dolan shop Information was collected about the number tye condition and placement of water spray nozzles on thedr and at the conveyor belt tranitions the cutter dr rotation rate (measured using a non-contact tachometer (T AC2K Dwyer Instrents Inc Michigan City Indiana) while the mill was rug) the hours on the machie the cutter dr condition and the cutter bits including their spacing condition make and model number NIOSH personnel worked with Payne amp Dolan sta and the manufactuers representative to install water flow meters and pressure gauges install new water spray nozzles and cutter bits and restore the water spray nozzles at the seconda conveyor tranition to the manufactuers specification This tie was also used to lear aboutthe operation of the machie and safe work practices

Water flow rate was measured using two water flow meters (Confowmeter II Confow Inc WashigtonP A) intaled in the water supply lies on the milL One meter was installed in the line between the water pump and the cutter dr spray bar The second meter was installed in the line between the water pump and the conveyor transition sprays (Figure 1 ) Water pressure was measured using pressure gauges attched to tee-fittgs

instaled in the water lie supplyig the cutter dr spray bar (Figue 2) in the water line

supplyigthe spray bar for the fist conveyor belt tranition and in the water lie supplyig the nozzles on the secondar conveyor transition The readings on thesemeters and gauges were obsered and recorded periodicaly thoughout both days of millig

Vehic1e speed and diection of trvel was meased using a Trible GeoXT hadheld data-loggig global positionig system (GPS) unt (Trible Navigation Ltd Sunyvale CA) receiver on the second day of millig The GPS unt was placed on padding on the top of the millig machie in an empty fi-extiguisher bracket (the extingusher had been relocated previously) in front of the operators station (Figue 3) Speed was also

4

observing and recording the foot speed reading on the intrent panel ofthe mil every two minutes As a measure recorded durng both days of miling by a NIOSH researcher

of productivity the time was recorded when each dump truck was loaded and pulled away from the millng machine

Depth of cut was measurecl every fifteen minutes during both milling days using a tape measure helcl at the edge of the cut pavement The width of the cut was measured as well Bulk samples of the miled pavement were collected on a periodic basis from

left in or next to the cut by the milling machine Wind speed and direction and temperature were recorded usigraveng a data-loggigraveug weather station (MultiLog Weather material

Station Fourier Systems Inc Atlanta GA) A hand-held muitigrave~directional impeller wind meter was also used during the survey (Skywatch Meteos JDC Electronic SA Yverdon-Ies-Bains Switzerland)

The work practices and use of personal protective equipment were recorded for each worker sampled including the workers position and distance relative to the miling machine (eg walking alongside following behind riding) Infomiation obtained from conversations with worlcers to detennine if the sampling days were typical of the nomial work load helped to place the sampling results in proper perspective Data were recorded describing other operations nearby that generated dust including the process its location relatIacuteve to the miling machine and whether it was upwind or downwind of the millng machine

Dust and Silca Sampling Methods

On both days of sampling personal breathing zone samples on the three members of the miling crew were collected at a flow rate of 42 liters per minute (Umin) using a battery-operated sampling pump at the employees waist connected via flexible tubing to a pre-weighed 37-mm diameter 5-micron (~m) pore-size polyvinyl chloride filter supported by a backup pad in a three-piece filter cassette sealed with a cellulose shrink band in accordance with NIOSH Methods 0600 and 7500 and a cyclone (GK 269 RespirableThoracic Cyclone BGi Inc Waltham MA) placed in the employees breathing zone (NIOSH 1994 HSE 1997)

Area samples were collected on both days of sampling at six locations on the millng instruments mounted on a metal frame (Figure 4) Themachine using an aray of

platform near the level controls onlocations included the dashboard on the operators

both sides of the mil near the cutter dr on both sides of the mil and on the right side

conveyor to the loading conveyor (Figure 5) The sampling intruments in each aray included a Ii ght-scattering aerosol photometer (pDR near the transition from the primary

Theano Electron Corp Franklin MA) with a 10 millmeter (mm) nylon cyclone comiected to the inlet via flexible tubing The pDR was in tur connected via flexible tubing to a battery-operated sampling pump calibrated at a flow rate of 17 Llmin A pre-weighed 5-~m pore-size polyvinyl chloride filter supported by a backup pad in a two-piece filter cassette sealed with a cellulose shr band was placed in line between the

5

pDR and the pump Also included in each sampling aray were two battery-operated sampling pumps both connected though flexible tubing to a 10-mm nylon cyclone and a pre-weighed 37-mm diameter 5-iexclm pore-size polyvnyl chloride filter supported by a backup pad in a two-piece filter cassette sealed with a cellulose shn band in accordance with NIOSH Methods 0600 and 7500

On the second day of sampling addigravetional area sauiples were collected at the six locations described above at a flow rate of 42 litersminute using a battery-operated sampling pump connected via flexible tubing to a pre-weighed 37-mm diameter 5shymicron (iexclm) pore-size polyvinyl chloride filter supported by a backup pad in a three-piece fiter cassette sealed with a cellulose shrink band in accordance with NIOSH Methods 0600 and 7500 and a cyclone (OK 269 RespirableThoracic Cyclone BGI Inc Waltham MA) attached to the metal frame

Gravimetric analysis for respirable pariculate was cared out with the fOllOWing modifications to NIOSH Method 0600 1) the fiters and backup pads were stored in an environmentally controlled room (201 1degC and 50i5 relative humidity) and were subj ected to the room conditions for at least two hours for stabilization prior to tare and gross weighing and 2) two weighings of the tare weight and gross weight were performed (NIOSH 1994) The difference between the average gross weight and the average tare weight was the result of the analysis The limit of detection for this method was 002 mg

Crystalline silica analysis ofthehigravegher-flow fiter and all bulk samples was perfornied using X-ray diffraction NIOSHMethod 7500 was used ith the following modifications 1) fiters were dissolved in tetraIgraveydrofurail rather than being ashed in a furace and 2) standards and samples were run concurently and an external calibration ciire was prepared from the integrated intensities rather than using the suggested normalization procedure (NIOSH 1994) These samples were analyzed for quarz and cristobalite The limits of detection for quarz and cristobalite on filters were 001 and 002 mg respectively The limit of quantiation is 003 mg for both quarz and cristobalite The lower-flow filter samples were not analyzed for silica

bulk samples collected from miled pavement left in or next to the cut by the millng machine The limit of detection for quar in bulk samples was 08 The limit of quantitation was 2

The silica content of the pavement was determined though testing of

Experimental design

Initial activities on site such as installing new water spray nozzles and new cutter-drm teeth were devoted to returing the mil to the manufacturers specifications DulIgraveng the

first day of sampling samples were collected over thee sampliacuteng periods during a typical miling job The second day of sampling was divided into four 2-hour periods During

the first period the manufacturer-specified nozzles (UniJetll model1 005 SS Spraying Systems Co Wheaton IL) rated at 05 gallons per minute (gpm) at 40 pounds per square

6

inch (psi) were used For the second and thd period higher-flow nozzles CUniJ etQI

model 11008 Spraying System Co Wheaton IL) rated at 08 gpm at 40 psi were installed on the cutter-dr spray bar Durng the final period the manufactuershy

specified nozzles were used again This design was used instead of a randomized design because of the length of time and effort required to change the nozzles in the field The spray nozzles for the primar conveyor and the material transfer conveyor were not changed Personal and high-flow area samples for respirable dust and respirable crystallne silica were changed approximately every two hours durig both sampling days The lower-flow area samples were collected for the full shift on both days

RESULTS AND DISCUSSION

Description of the Mil and the Controls

The miling machine used at this site had 3560 hours on the machine at the beginnng of the site visit It was equipped with water spray nozzles at three places including dr spraying nozzles primar conveyor spraying nozzles and material transfer conveying nozzles There were 18 flat fan spray nozzles (UniJetQI model 11005 SS Spraying Systems Co Wheaton IL) mounted on a spragravey bar in the cutter dru housing This type

of nozzle was used at all of the installations on this milL Thegrave fist thee nozzles on the cutter dr spray bar were mounted 2 inches (in) apar the thrd and fourh nozzle were

mounted 3 in apar and the remaining nozzles were 5 Yi in apar The cutter dr

extension was served by a separate spray bar equipped with thee nozzles The first two nozzles were 2in apar while the second and thrd nozzle were 5 Yi in apar There were a total of nine nozzles at the primary conveyor installed at the transition from the cutter dr to the primar conveyor four were mounted on each side and one on the extension

These nozzles were 1 foot apar There were two nozzles mounted above the material transfer conveyor at the transition from the primar cogravenveyor Those nozzles were 32 in apar New nozzles were installed on the evening before the first sampling day The water pump for the spraying system is rated at 40 Llmin (106 gallons) of water at 3 Yi bar (51 psi)

The 8 ft 6 in wide cutter dr held 193 bits aranged in a helical coil around the dr

holders were in factory spec condition with 50 hrs on the holders NewThe drm and

bits were installed on the evening before the first sampling day and were changed several times durg the next two days The dr rotation was measured and found to agree with

the manufacturers specification of928 rpm

Personal protective equipment and work practices

The miling crew members wore hard hats (except the operator) safety glasses and traffc safety vests The operator was the only employee who spent all of his time on the mil operating the mil from either the right or left side of the operators station The foreman spent the majority of the first day operatig the rear controls while the thid ecircrewman performed tasks such as operating a skid-steer loader and drvig the water

7

in the afternoon the foreman operated the skid steer loader while the third crewman ran the rear controls For the most par the skid-steer loader was not operated near the miling machine on the first day On one occasion a road grader passed by and for a brief period in the afternoon nugravellig took place alongside a field while a farer was running a combine On the second day the skid-steer loader

truck (Figure 6) However

the daythe day and the third crew member spent most ofwas idle for the majority of

the rear controls The foreman left the migravelperiodically to attend torunning one of

matters such as trck scheduling On both days the trcks assigned to take away thepossiblethe road unti that was no longermiled material drove on the paved portion of

lessening the potential of dust being generated by the trucks as they passed the millng machine

Respirable dust and crystallne silica sampling results

personal breathing zone sampling for respirable dust and crystalline silica conducted on October 8 are presented in Table 1 On October 8 which represented a typical millng day respirable dust results ranged from 014 to 183 mgm The TW A respirable dust exposures for the three employees were 026 mgmJ (499 minutes) for the

The results of

operator 10 mgm3 (495 minutes) for the foreman and 038 mgm3 (438 minutes) for the third employee who began the day operatin~ the skid steer loader Their 8-hour TWAs were 027 mgm3 for the operator 10 mgm for the foreman and 035 mgm3 for the third crew member The OSHA PELs for these employees calculated based upon the percent silica in their samples were 142 mgm 3 for the operator 117 mgm3 for the foreman and 113 mgm3 for the third member of the miling crew The PELs were calculated using the value of the LODJ for quarz values below the LOD (Hornung and Reed 1990) None of the employees exposures exceeded the OSHA PEL on October 8 as a TW A but excursions above the PEL did take place during the first two sampling periods for the foreman who spent most of those periods operating the rear controls on the mUL

Respirable quarz results from personal samples ranged from below the limit of to

detection 01 1 inglm3 The TW A respirable quarz exposures for October 8 were 0013 mgm3 for the operator 0064 mgm3 for the foreman and 0030 mgm3 for the third

LOD formiling Crew member The TWAs were also calculated using the value of

001 mg Their 8-hour quartz TWAs were 0014 mgm3 0066 mglm3 and 0027 mgm3 respectively On October 8 the foremans TWA and 8-hour TWA exposure exceeded the NIOSH quarz REL of 005 nigm3

quarz results less than the LOD of

the milling crews respirable dust and respirable quartzTable 2 lists the results of

exposures by nozzle type and employee results in TWAs of21 mgm3 for the operator 062 mgm3 for the foreman and 11 mgm3 for the rear control operator for the UniJ etfI 11005 nozzle versus 14 mglm3 065 mgm3 and 089 mgm respectively forthe UniJetaeligl 11008 nozzle TWA

samples on October 9 Calculating TWA respirable dust

the operator 0041

mgm3 for the foreman and 0050 mgin3 for the worker operating the rear controls quartz results for the UniJetfI 11005 nozzle were 012 mgm3 for

8

0081 mgm3 for the operator TW A quarz results for the UniacuteJetlIII008 nozzle were

0041 mgm3 for the foreman and 0043 mgm3 for the thrd crewman In contrast to October 8 the operator received the highest exposures on the second sampling day

Table 3 shows that the highest emissionsthe nozzle type Inspection ofregardless of

side of the mil and the upper conveyor Unfortunately the weather station did not log data so the effect of the wind direction on those results is unnown

were associated with the left

the area samplescoUected on October 8 with the lower-flow respirable dust samplers (17 Lmin) and the pdR direct-reading instruments Those results indicate that for both sampling methods that exposures were lowest igraven the

Table 4 reports the results of

operators station and highest at the upper conveyor (the material transfer conveyor) This table also lists the gravimetricpDR ratios calculated for each sampling location These ratios were used to adjust pDR short teimsampling concentrations which are provided later in ths report Table 5 presents the results for the lower-flow respirable

dust samples and the pdR samples for October 9 including the results from all nozzle types The upper conveyor produced the highest exposure on that day as welL Perhaps the operators personal exposures differ from the area sample at his work station because

the time on one or the other side of the mm while the sampler was in the

he spends most of

his work station (Figure 7) Table 5 which provides the results ofthe center of

lower-flow andpdR area samples shows that as in Table 3 the highest emissions were associated with the left side of the mill and the upper conveyor The migraveU removed

the road so the left side oftlie mm was facing the pavedmaterial from the right side of

the road while the right side faced the previous cut This orientation may explain the milL The manufacturers

edge of

in par why the exposures were higher on the left side of

6 relates area samplingrepresentative attributed this result to passing truck trame Table

results to productivity water flow and water spray pressure while Table 7 describes the work done on October 9

When reviewing the results of sampling conducted on October 9 for the purpose of this study it is useful to compare the results obtained when the different water spray nozzles

logwere used For the purpose ofthisaualysis the results were converted to the natural

the data did not vary with(In) scale because on the log scale the varabmty of

concentration From the In scale analysis of the respirable dust results (Tables 8~ II) the ratio of the UniJ etlf 11005 nozzle to the DniJ et(szlig i 1008 nozzle results is the ratio of their geometric means 12 This indicates that the respirable dust measurements obtained

are about 20 higher thotigh the result is not statistically significant even at the lO signifcance leveL Results for the pDRs are while the UniJetlf 11005 nozzle was used

also about 20 higher for the UnijetQ 11005 and are also notsimilar Those results are

statistically significant at the 10 leveL Examination oftbe tables indicates that for mostthe

groupings the UniJetlIl1005 nozzle does give higher results Review of all of

the UniacuteJet(( 11005 nozzle resultsrespirable dust data from October 9 shows that 59 of

exceeded the PEL while 50 of the UniJetI 11008 nozzle results did so For personal breathing zone samples half of the results while the Unijet(szlig 11005 was in use exceeded

the UnijetlI 11008 results exceeded the PELthe PEL one third of

9

From the In scale analysis of the quarz samplig results (Tables 12-15) the ratio of the Uniet(szlig 11005 nozzle to the Uniet(szlig 11008 nozzle results is the ratio of their geometrc means 116 Thus for respirable quar the results while Uniet(szlig i 1005 nozzles were intalled on the cutter drm were about 16 higher though the result is not statisticaly signficant even at the 10 signcance leveL Examation of the tables indicates that the quar results are not as consistent as those for respirable dust For data from both days 7 respirable quar results were less than the LOD and 13 values were between LOD and LOQ For the seven quarz values below the LOD the value Lan was substituted

Quarz in bulk samples

The results of 10 bulk samples ranged from 12 to 28 with a mean of 199 and a median of 185

CONCLUSIONS AN RECOMMNDATIONS

Conclusions from ths pilot study regardig the effect of increasing the water flow to the spray nozzles on dust and quart exposures are lited by several factors First the higher flow nozzles were only intalled on the cutter dr and the cutter dr extension

the nozzles selected represent a difference of only 30 more flow when the higher-flow nozzles were installed Nevereless the respirable dust measurements obtaied while the Uniet(szlig 11005 nozzles were used were about 20 higher than when the higher-flow Uniet(szlig 11008 nozzles were used The respirable quarz results while Uniet(szlig 11005 nozzles were installed on the cutter dr were about 16 higher Neither

Second

the reductions in respirable dust concentrations nor those for the quarz results were statistically signficant even at the lO signficance leveL Statistical signficance mean that the difference is not due to chance alone

Research on dust controls in minig has shown that water sprays have two roles wetting of broken material being transported and airborne captue (NOSH 2003) Uniformly wetting the broken material durg the breakage process is far more effective and enures that dust paricles stay attached to the materal (NQSH 2003) Increasing the water flow rate and increasing the number of sprays have both been shown to be effective it is tooearly in this proj ect to recommend an approach In one inance dust from a shearer dr was reduced by 60 when the 46 smaler orifice nozzles were substituted for the originall7 nozzles with the pressure and flow held constant (NOSH 2003) The shape of the spray is another importnt factor in its effectveness

Futue studies might test the water system on a newer-model machie to begi to explore the relationship between water flow and pressue agravend aiborne dust concentrtions Varables related to the site andjob might obscure ths relationship but it is hoped that a trend might emerge

10

REFERENCES

29 CFR 19101000 (2001) Occupational Safety and Health Admstration air

containants

29 CFR 192655 (2003) Occupational Safety and Health Adminstration gases vapors fues dusts and mists

ACGrn (2004) Theshold limit values for chemical substances CincinatiOH American Conference of Governental Industral Hygienists

Akbar-Khanadeh F Brillhar RL (2002) Respirable crystallne silca dust exposure durng concrete finshing (grnding) using hand-held grnders in the constrction industr An occup Hyg 46341-346

Bureau of Mines (1992) Crystallne silica primer Washigton DC US Deparent of the Interior Bureau of Mines Branch of Industral Minerals Special Publication

Glindmeyer HW Hamad YY (1988) Contributing factors to sandblasters silcosis inadequate respiratory protection equipment and standards J accup Med 30917-921

HSE (1997) MDHS 142 General methods for sampling and gravimetrc analysis of respirable and total inhalable dust Methods for the determination of hazardous substances lIealth and safety laboratory Sudbur Suffolk UK Health and Safety Executive

Homuug R Reed L (1990) Estimation of average concentration in the presence of nondetectable values Applied Occupational and Environmental Hygiene 5(1)46-51

Linch KD (2002) Respirable concrete dust-silcosis hazard in the constrction industr

Appl Occup and Environ Hyg 17 209-221

Neuhauser Curt (curneuhauser(ecircdotstatewius) (2004) RE US 12 project Private e-mail message to Alan Echt (AEcht(ecirccdcgov) Januar 7

New Jersey Deparent of Health and Senior Services (2001) New Jersey silica parership In Occupational Health Sureilance Update February Trenton NJ NJ

Deparment of Health and Senior Services Division of Epidemiology Environmental and Occupational Health Occupational Health Service Occupational Health Sureilance Program

11

OCCUPATIONAL EXPOSUR TO CRYSTALLIN SILICA

Silcosis is an occupational respiratory disease caused by inaling respirable crystalline

silca dust Silcosis is irreversible often progressive (even after exposure has ceased)

and potentially fataL Because no effective treatment exists for silicosis prevention though exposure control is essentiaL Exposure to respirable crystalline silca dust occurs in many occupations including constrction Crystalline silca refers to a group of minerals composed of silcon and oxygen a crystalline strctue is one in which the atoms are aranged in a repeating three-dimensional pattern (Bureau of Mines 1992) The three major forms of crystalline silca are quartz cristobalite and trdymite quar is the most common form (Bureau of Mines 1992) Respirable refers to that portion of airborne crystalline silca that is capable of entering the gas-exchange regions of the lungs if inhaled this includes paricles with aerodynamc diameters less than approximately 10

Ilm (NOSH 2002)

When proper practices are not followed or controls are not maintained respirable crystallne silica exposures can exceed the NIaSH Recommended Exposure Limit

Permssible Exposure Limit (PEL) or the American Conference of(RL) the OSHA

Governental Industral Hygienists (ACGIH) Threshold Limit Value (TLV) (NOSH 200229 CFR 19101000 ACGll 2004) NiaSH recommends an exposure limit of 005 mgm3 to reduce the risk of developing silicosis lung cancer and other adverse health effects

The OSHA PEL for respirable dust containing 1 quarz or more in general industr is expressed as an equation (29 CFR 19101000)

10 mgm3 Respirable PEL =

Silca + 2

If for example the dust contai no crystalline silica the PEL is 5 mgm3 and if the dust is 100 crystalline silca the PEL is 01 mgm3 For trdymite and cristobalite OSHA uses half the value calculated using the formula for quarz (29 CPR 19101000)

The curent OSHA permissible exposure limit (PEL) for respirable dust containng crystallne silica (quartz) for the constrction industr is measured by impinger sampling The PEL is expressed in millons of paricles per cubic foot (mppcf) and is calculated using the following formula (29 CFR 192655)

250 mppcf Respirable PEL =

Silca + 5

3

Since the PELs were adopted the impinger sampling method ha been rendered obsolete by gravimetrc sampling (OSHA 1996) OSHA is not aware of any goverent agencies or employers in ths countr that are curently usng impinger sampling to assess worker

exposure to dust containig crystallne silca and impinger samples are generally

recogned as being less reliable than gravimetrc samples (OSHA 1996) OSHA has determed that sampling procedures in the consction industr should be the same as in general industr and that the mppcfPEL in 29 CFR 192655(a) is equivalent to the mgm3 PEL in 29 CFR 19101000 (aSHA 1996)

The ACGrnCE TL VIs for cristobalte quar and trdymte are all 005 mglm3 (ACGm 2004) The ACGrn~ ha published a notice of their intent to change the TL ~ for (Xshyquar and cristobalte (respirable fraction) to 0025 mgm3 and to withdraw the documentation and adopted TL yi for trdymte (ACGrn 2004)

METHODS

Descriptive data about the millig machie were gathered durng the aferoon and evening prior to the fist day of sampling while the machie was undergoing repais at the Payne amp Dolan shop Information was collected about the number tye condition and placement of water spray nozzles on thedr and at the conveyor belt tranitions the cutter dr rotation rate (measured using a non-contact tachometer (T AC2K Dwyer Instrents Inc Michigan City Indiana) while the mill was rug) the hours on the machie the cutter dr condition and the cutter bits including their spacing condition make and model number NIOSH personnel worked with Payne amp Dolan sta and the manufactuers representative to install water flow meters and pressure gauges install new water spray nozzles and cutter bits and restore the water spray nozzles at the seconda conveyor tranition to the manufactuers specification This tie was also used to lear aboutthe operation of the machie and safe work practices

Water flow rate was measured using two water flow meters (Confowmeter II Confow Inc WashigtonP A) intaled in the water supply lies on the milL One meter was installed in the line between the water pump and the cutter dr spray bar The second meter was installed in the line between the water pump and the conveyor transition sprays (Figure 1 ) Water pressure was measured using pressure gauges attched to tee-fittgs

instaled in the water lie supplyig the cutter dr spray bar (Figue 2) in the water line

supplyigthe spray bar for the fist conveyor belt tranition and in the water lie supplyig the nozzles on the secondar conveyor transition The readings on thesemeters and gauges were obsered and recorded periodicaly thoughout both days of millig

Vehic1e speed and diection of trvel was meased using a Trible GeoXT hadheld data-loggig global positionig system (GPS) unt (Trible Navigation Ltd Sunyvale CA) receiver on the second day of millig The GPS unt was placed on padding on the top of the millig machie in an empty fi-extiguisher bracket (the extingusher had been relocated previously) in front of the operators station (Figue 3) Speed was also

4

observing and recording the foot speed reading on the intrent panel ofthe mil every two minutes As a measure recorded durng both days of miling by a NIOSH researcher

of productivity the time was recorded when each dump truck was loaded and pulled away from the millng machine

Depth of cut was measurecl every fifteen minutes during both milling days using a tape measure helcl at the edge of the cut pavement The width of the cut was measured as well Bulk samples of the miled pavement were collected on a periodic basis from

left in or next to the cut by the milling machine Wind speed and direction and temperature were recorded usigraveng a data-loggigraveug weather station (MultiLog Weather material

Station Fourier Systems Inc Atlanta GA) A hand-held muitigrave~directional impeller wind meter was also used during the survey (Skywatch Meteos JDC Electronic SA Yverdon-Ies-Bains Switzerland)

The work practices and use of personal protective equipment were recorded for each worker sampled including the workers position and distance relative to the miling machine (eg walking alongside following behind riding) Infomiation obtained from conversations with worlcers to detennine if the sampling days were typical of the nomial work load helped to place the sampling results in proper perspective Data were recorded describing other operations nearby that generated dust including the process its location relatIacuteve to the miling machine and whether it was upwind or downwind of the millng machine

Dust and Silca Sampling Methods

On both days of sampling personal breathing zone samples on the three members of the miling crew were collected at a flow rate of 42 liters per minute (Umin) using a battery-operated sampling pump at the employees waist connected via flexible tubing to a pre-weighed 37-mm diameter 5-micron (~m) pore-size polyvinyl chloride filter supported by a backup pad in a three-piece filter cassette sealed with a cellulose shrink band in accordance with NIOSH Methods 0600 and 7500 and a cyclone (GK 269 RespirableThoracic Cyclone BGi Inc Waltham MA) placed in the employees breathing zone (NIOSH 1994 HSE 1997)

Area samples were collected on both days of sampling at six locations on the millng instruments mounted on a metal frame (Figure 4) Themachine using an aray of

platform near the level controls onlocations included the dashboard on the operators

both sides of the mil near the cutter dr on both sides of the mil and on the right side

conveyor to the loading conveyor (Figure 5) The sampling intruments in each aray included a Ii ght-scattering aerosol photometer (pDR near the transition from the primary

Theano Electron Corp Franklin MA) with a 10 millmeter (mm) nylon cyclone comiected to the inlet via flexible tubing The pDR was in tur connected via flexible tubing to a battery-operated sampling pump calibrated at a flow rate of 17 Llmin A pre-weighed 5-~m pore-size polyvinyl chloride filter supported by a backup pad in a two-piece filter cassette sealed with a cellulose shr band was placed in line between the

5

pDR and the pump Also included in each sampling aray were two battery-operated sampling pumps both connected though flexible tubing to a 10-mm nylon cyclone and a pre-weighed 37-mm diameter 5-iexclm pore-size polyvnyl chloride filter supported by a backup pad in a two-piece filter cassette sealed with a cellulose shn band in accordance with NIOSH Methods 0600 and 7500

On the second day of sampling addigravetional area sauiples were collected at the six locations described above at a flow rate of 42 litersminute using a battery-operated sampling pump connected via flexible tubing to a pre-weighed 37-mm diameter 5shymicron (iexclm) pore-size polyvinyl chloride filter supported by a backup pad in a three-piece fiter cassette sealed with a cellulose shrink band in accordance with NIOSH Methods 0600 and 7500 and a cyclone (OK 269 RespirableThoracic Cyclone BGI Inc Waltham MA) attached to the metal frame

Gravimetric analysis for respirable pariculate was cared out with the fOllOWing modifications to NIOSH Method 0600 1) the fiters and backup pads were stored in an environmentally controlled room (201 1degC and 50i5 relative humidity) and were subj ected to the room conditions for at least two hours for stabilization prior to tare and gross weighing and 2) two weighings of the tare weight and gross weight were performed (NIOSH 1994) The difference between the average gross weight and the average tare weight was the result of the analysis The limit of detection for this method was 002 mg

Crystalline silica analysis ofthehigravegher-flow fiter and all bulk samples was perfornied using X-ray diffraction NIOSHMethod 7500 was used ith the following modifications 1) fiters were dissolved in tetraIgraveydrofurail rather than being ashed in a furace and 2) standards and samples were run concurently and an external calibration ciire was prepared from the integrated intensities rather than using the suggested normalization procedure (NIOSH 1994) These samples were analyzed for quarz and cristobalite The limits of detection for quarz and cristobalite on filters were 001 and 002 mg respectively The limit of quantiation is 003 mg for both quarz and cristobalite The lower-flow filter samples were not analyzed for silica

bulk samples collected from miled pavement left in or next to the cut by the millng machine The limit of detection for quar in bulk samples was 08 The limit of quantitation was 2

The silica content of the pavement was determined though testing of

Experimental design

Initial activities on site such as installing new water spray nozzles and new cutter-drm teeth were devoted to returing the mil to the manufacturers specifications DulIgraveng the

first day of sampling samples were collected over thee sampliacuteng periods during a typical miling job The second day of sampling was divided into four 2-hour periods During

the first period the manufacturer-specified nozzles (UniJetll model1 005 SS Spraying Systems Co Wheaton IL) rated at 05 gallons per minute (gpm) at 40 pounds per square

6

inch (psi) were used For the second and thd period higher-flow nozzles CUniJ etQI

model 11008 Spraying System Co Wheaton IL) rated at 08 gpm at 40 psi were installed on the cutter-dr spray bar Durng the final period the manufactuershy

specified nozzles were used again This design was used instead of a randomized design because of the length of time and effort required to change the nozzles in the field The spray nozzles for the primar conveyor and the material transfer conveyor were not changed Personal and high-flow area samples for respirable dust and respirable crystallne silica were changed approximately every two hours durig both sampling days The lower-flow area samples were collected for the full shift on both days

RESULTS AND DISCUSSION

Description of the Mil and the Controls

The miling machine used at this site had 3560 hours on the machine at the beginnng of the site visit It was equipped with water spray nozzles at three places including dr spraying nozzles primar conveyor spraying nozzles and material transfer conveying nozzles There were 18 flat fan spray nozzles (UniJetQI model 11005 SS Spraying Systems Co Wheaton IL) mounted on a spragravey bar in the cutter dru housing This type

of nozzle was used at all of the installations on this milL Thegrave fist thee nozzles on the cutter dr spray bar were mounted 2 inches (in) apar the thrd and fourh nozzle were

mounted 3 in apar and the remaining nozzles were 5 Yi in apar The cutter dr

extension was served by a separate spray bar equipped with thee nozzles The first two nozzles were 2in apar while the second and thrd nozzle were 5 Yi in apar There were a total of nine nozzles at the primary conveyor installed at the transition from the cutter dr to the primar conveyor four were mounted on each side and one on the extension

These nozzles were 1 foot apar There were two nozzles mounted above the material transfer conveyor at the transition from the primar cogravenveyor Those nozzles were 32 in apar New nozzles were installed on the evening before the first sampling day The water pump for the spraying system is rated at 40 Llmin (106 gallons) of water at 3 Yi bar (51 psi)

The 8 ft 6 in wide cutter dr held 193 bits aranged in a helical coil around the dr

holders were in factory spec condition with 50 hrs on the holders NewThe drm and

bits were installed on the evening before the first sampling day and were changed several times durg the next two days The dr rotation was measured and found to agree with

the manufacturers specification of928 rpm

Personal protective equipment and work practices

The miling crew members wore hard hats (except the operator) safety glasses and traffc safety vests The operator was the only employee who spent all of his time on the mil operating the mil from either the right or left side of the operators station The foreman spent the majority of the first day operatig the rear controls while the thid ecircrewman performed tasks such as operating a skid-steer loader and drvig the water

7

in the afternoon the foreman operated the skid steer loader while the third crewman ran the rear controls For the most par the skid-steer loader was not operated near the miling machine on the first day On one occasion a road grader passed by and for a brief period in the afternoon nugravellig took place alongside a field while a farer was running a combine On the second day the skid-steer loader

truck (Figure 6) However

the daythe day and the third crew member spent most ofwas idle for the majority of

the rear controls The foreman left the migravelperiodically to attend torunning one of

matters such as trck scheduling On both days the trcks assigned to take away thepossiblethe road unti that was no longermiled material drove on the paved portion of

lessening the potential of dust being generated by the trucks as they passed the millng machine

Respirable dust and crystallne silica sampling results

personal breathing zone sampling for respirable dust and crystalline silica conducted on October 8 are presented in Table 1 On October 8 which represented a typical millng day respirable dust results ranged from 014 to 183 mgm The TW A respirable dust exposures for the three employees were 026 mgmJ (499 minutes) for the

The results of

operator 10 mgm3 (495 minutes) for the foreman and 038 mgm3 (438 minutes) for the third employee who began the day operatin~ the skid steer loader Their 8-hour TWAs were 027 mgm3 for the operator 10 mgm for the foreman and 035 mgm3 for the third crew member The OSHA PELs for these employees calculated based upon the percent silica in their samples were 142 mgm 3 for the operator 117 mgm3 for the foreman and 113 mgm3 for the third member of the miling crew The PELs were calculated using the value of the LODJ for quarz values below the LOD (Hornung and Reed 1990) None of the employees exposures exceeded the OSHA PEL on October 8 as a TW A but excursions above the PEL did take place during the first two sampling periods for the foreman who spent most of those periods operating the rear controls on the mUL

Respirable quarz results from personal samples ranged from below the limit of to

detection 01 1 inglm3 The TW A respirable quarz exposures for October 8 were 0013 mgm3 for the operator 0064 mgm3 for the foreman and 0030 mgm3 for the third

LOD formiling Crew member The TWAs were also calculated using the value of

001 mg Their 8-hour quartz TWAs were 0014 mgm3 0066 mglm3 and 0027 mgm3 respectively On October 8 the foremans TWA and 8-hour TWA exposure exceeded the NIOSH quarz REL of 005 nigm3

quarz results less than the LOD of

the milling crews respirable dust and respirable quartzTable 2 lists the results of

exposures by nozzle type and employee results in TWAs of21 mgm3 for the operator 062 mgm3 for the foreman and 11 mgm3 for the rear control operator for the UniJ etfI 11005 nozzle versus 14 mglm3 065 mgm3 and 089 mgm respectively forthe UniJetaeligl 11008 nozzle TWA

samples on October 9 Calculating TWA respirable dust

the operator 0041

mgm3 for the foreman and 0050 mgin3 for the worker operating the rear controls quartz results for the UniJetfI 11005 nozzle were 012 mgm3 for

8

0081 mgm3 for the operator TW A quarz results for the UniacuteJetlIII008 nozzle were

0041 mgm3 for the foreman and 0043 mgm3 for the thrd crewman In contrast to October 8 the operator received the highest exposures on the second sampling day

Table 3 shows that the highest emissionsthe nozzle type Inspection ofregardless of

side of the mil and the upper conveyor Unfortunately the weather station did not log data so the effect of the wind direction on those results is unnown

were associated with the left

the area samplescoUected on October 8 with the lower-flow respirable dust samplers (17 Lmin) and the pdR direct-reading instruments Those results indicate that for both sampling methods that exposures were lowest igraven the

Table 4 reports the results of

operators station and highest at the upper conveyor (the material transfer conveyor) This table also lists the gravimetricpDR ratios calculated for each sampling location These ratios were used to adjust pDR short teimsampling concentrations which are provided later in ths report Table 5 presents the results for the lower-flow respirable

dust samples and the pdR samples for October 9 including the results from all nozzle types The upper conveyor produced the highest exposure on that day as welL Perhaps the operators personal exposures differ from the area sample at his work station because

the time on one or the other side of the mm while the sampler was in the

he spends most of

his work station (Figure 7) Table 5 which provides the results ofthe center of

lower-flow andpdR area samples shows that as in Table 3 the highest emissions were associated with the left side of the mill and the upper conveyor The migraveU removed

the road so the left side oftlie mm was facing the pavedmaterial from the right side of

the road while the right side faced the previous cut This orientation may explain the milL The manufacturers

edge of

in par why the exposures were higher on the left side of

6 relates area samplingrepresentative attributed this result to passing truck trame Table

results to productivity water flow and water spray pressure while Table 7 describes the work done on October 9

When reviewing the results of sampling conducted on October 9 for the purpose of this study it is useful to compare the results obtained when the different water spray nozzles

logwere used For the purpose ofthisaualysis the results were converted to the natural

the data did not vary with(In) scale because on the log scale the varabmty of

concentration From the In scale analysis of the respirable dust results (Tables 8~ II) the ratio of the UniJ etlf 11005 nozzle to the DniJ et(szlig i 1008 nozzle results is the ratio of their geometric means 12 This indicates that the respirable dust measurements obtained

are about 20 higher thotigh the result is not statistically significant even at the lO signifcance leveL Results for the pDRs are while the UniJetlf 11005 nozzle was used

also about 20 higher for the UnijetQ 11005 and are also notsimilar Those results are

statistically significant at the 10 leveL Examination oftbe tables indicates that for mostthe

groupings the UniJetlIl1005 nozzle does give higher results Review of all of

the UniacuteJet(( 11005 nozzle resultsrespirable dust data from October 9 shows that 59 of

exceeded the PEL while 50 of the UniJetI 11008 nozzle results did so For personal breathing zone samples half of the results while the Unijet(szlig 11005 was in use exceeded

the UnijetlI 11008 results exceeded the PELthe PEL one third of

9

From the In scale analysis of the quarz samplig results (Tables 12-15) the ratio of the Uniet(szlig 11005 nozzle to the Uniet(szlig 11008 nozzle results is the ratio of their geometrc means 116 Thus for respirable quar the results while Uniet(szlig i 1005 nozzles were intalled on the cutter drm were about 16 higher though the result is not statisticaly signficant even at the 10 signcance leveL Examation of the tables indicates that the quar results are not as consistent as those for respirable dust For data from both days 7 respirable quar results were less than the LOD and 13 values were between LOD and LOQ For the seven quarz values below the LOD the value Lan was substituted

Quarz in bulk samples

The results of 10 bulk samples ranged from 12 to 28 with a mean of 199 and a median of 185

CONCLUSIONS AN RECOMMNDATIONS

Conclusions from ths pilot study regardig the effect of increasing the water flow to the spray nozzles on dust and quart exposures are lited by several factors First the higher flow nozzles were only intalled on the cutter dr and the cutter dr extension

the nozzles selected represent a difference of only 30 more flow when the higher-flow nozzles were installed Nevereless the respirable dust measurements obtaied while the Uniet(szlig 11005 nozzles were used were about 20 higher than when the higher-flow Uniet(szlig 11008 nozzles were used The respirable quarz results while Uniet(szlig 11005 nozzles were installed on the cutter dr were about 16 higher Neither

Second

the reductions in respirable dust concentrations nor those for the quarz results were statistically signficant even at the lO signficance leveL Statistical signficance mean that the difference is not due to chance alone

Research on dust controls in minig has shown that water sprays have two roles wetting of broken material being transported and airborne captue (NOSH 2003) Uniformly wetting the broken material durg the breakage process is far more effective and enures that dust paricles stay attached to the materal (NQSH 2003) Increasing the water flow rate and increasing the number of sprays have both been shown to be effective it is tooearly in this proj ect to recommend an approach In one inance dust from a shearer dr was reduced by 60 when the 46 smaler orifice nozzles were substituted for the originall7 nozzles with the pressure and flow held constant (NOSH 2003) The shape of the spray is another importnt factor in its effectveness

Futue studies might test the water system on a newer-model machie to begi to explore the relationship between water flow and pressue agravend aiborne dust concentrtions Varables related to the site andjob might obscure ths relationship but it is hoped that a trend might emerge

10

REFERENCES

29 CFR 19101000 (2001) Occupational Safety and Health Admstration air

containants

29 CFR 192655 (2003) Occupational Safety and Health Adminstration gases vapors fues dusts and mists

ACGrn (2004) Theshold limit values for chemical substances CincinatiOH American Conference of Governental Industral Hygienists

Akbar-Khanadeh F Brillhar RL (2002) Respirable crystallne silca dust exposure durng concrete finshing (grnding) using hand-held grnders in the constrction industr An occup Hyg 46341-346

Bureau of Mines (1992) Crystallne silica primer Washigton DC US Deparent of the Interior Bureau of Mines Branch of Industral Minerals Special Publication

Glindmeyer HW Hamad YY (1988) Contributing factors to sandblasters silcosis inadequate respiratory protection equipment and standards J accup Med 30917-921

HSE (1997) MDHS 142 General methods for sampling and gravimetrc analysis of respirable and total inhalable dust Methods for the determination of hazardous substances lIealth and safety laboratory Sudbur Suffolk UK Health and Safety Executive

Homuug R Reed L (1990) Estimation of average concentration in the presence of nondetectable values Applied Occupational and Environmental Hygiene 5(1)46-51

Linch KD (2002) Respirable concrete dust-silcosis hazard in the constrction industr

Appl Occup and Environ Hyg 17 209-221

Neuhauser Curt (curneuhauser(ecircdotstatewius) (2004) RE US 12 project Private e-mail message to Alan Echt (AEcht(ecirccdcgov) Januar 7

New Jersey Deparent of Health and Senior Services (2001) New Jersey silica parership In Occupational Health Sureilance Update February Trenton NJ NJ

Deparment of Health and Senior Services Division of Epidemiology Environmental and Occupational Health Occupational Health Service Occupational Health Sureilance Program

11

Since the PELs were adopted the impinger sampling method ha been rendered obsolete by gravimetrc sampling (OSHA 1996) OSHA is not aware of any goverent agencies or employers in ths countr that are curently usng impinger sampling to assess worker

exposure to dust containig crystallne silca and impinger samples are generally

recogned as being less reliable than gravimetrc samples (OSHA 1996) OSHA has determed that sampling procedures in the consction industr should be the same as in general industr and that the mppcfPEL in 29 CFR 192655(a) is equivalent to the mgm3 PEL in 29 CFR 19101000 (aSHA 1996)

The ACGrnCE TL VIs for cristobalte quar and trdymte are all 005 mglm3 (ACGm 2004) The ACGrn~ ha published a notice of their intent to change the TL ~ for (Xshyquar and cristobalte (respirable fraction) to 0025 mgm3 and to withdraw the documentation and adopted TL yi for trdymte (ACGrn 2004)

METHODS

Descriptive data about the millig machie were gathered durng the aferoon and evening prior to the fist day of sampling while the machie was undergoing repais at the Payne amp Dolan shop Information was collected about the number tye condition and placement of water spray nozzles on thedr and at the conveyor belt tranitions the cutter dr rotation rate (measured using a non-contact tachometer (T AC2K Dwyer Instrents Inc Michigan City Indiana) while the mill was rug) the hours on the machie the cutter dr condition and the cutter bits including their spacing condition make and model number NIOSH personnel worked with Payne amp Dolan sta and the manufactuers representative to install water flow meters and pressure gauges install new water spray nozzles and cutter bits and restore the water spray nozzles at the seconda conveyor tranition to the manufactuers specification This tie was also used to lear aboutthe operation of the machie and safe work practices

Water flow rate was measured using two water flow meters (Confowmeter II Confow Inc WashigtonP A) intaled in the water supply lies on the milL One meter was installed in the line between the water pump and the cutter dr spray bar The second meter was installed in the line between the water pump and the conveyor transition sprays (Figure 1 ) Water pressure was measured using pressure gauges attched to tee-fittgs

instaled in the water lie supplyig the cutter dr spray bar (Figue 2) in the water line

supplyigthe spray bar for the fist conveyor belt tranition and in the water lie supplyig the nozzles on the secondar conveyor transition The readings on thesemeters and gauges were obsered and recorded periodicaly thoughout both days of millig

Vehic1e speed and diection of trvel was meased using a Trible GeoXT hadheld data-loggig global positionig system (GPS) unt (Trible Navigation Ltd Sunyvale CA) receiver on the second day of millig The GPS unt was placed on padding on the top of the millig machie in an empty fi-extiguisher bracket (the extingusher had been relocated previously) in front of the operators station (Figue 3) Speed was also

4

observing and recording the foot speed reading on the intrent panel ofthe mil every two minutes As a measure recorded durng both days of miling by a NIOSH researcher

of productivity the time was recorded when each dump truck was loaded and pulled away from the millng machine

Depth of cut was measurecl every fifteen minutes during both milling days using a tape measure helcl at the edge of the cut pavement The width of the cut was measured as well Bulk samples of the miled pavement were collected on a periodic basis from

left in or next to the cut by the milling machine Wind speed and direction and temperature were recorded usigraveng a data-loggigraveug weather station (MultiLog Weather material

Station Fourier Systems Inc Atlanta GA) A hand-held muitigrave~directional impeller wind meter was also used during the survey (Skywatch Meteos JDC Electronic SA Yverdon-Ies-Bains Switzerland)

The work practices and use of personal protective equipment were recorded for each worker sampled including the workers position and distance relative to the miling machine (eg walking alongside following behind riding) Infomiation obtained from conversations with worlcers to detennine if the sampling days were typical of the nomial work load helped to place the sampling results in proper perspective Data were recorded describing other operations nearby that generated dust including the process its location relatIacuteve to the miling machine and whether it was upwind or downwind of the millng machine

Dust and Silca Sampling Methods

On both days of sampling personal breathing zone samples on the three members of the miling crew were collected at a flow rate of 42 liters per minute (Umin) using a battery-operated sampling pump at the employees waist connected via flexible tubing to a pre-weighed 37-mm diameter 5-micron (~m) pore-size polyvinyl chloride filter supported by a backup pad in a three-piece filter cassette sealed with a cellulose shrink band in accordance with NIOSH Methods 0600 and 7500 and a cyclone (GK 269 RespirableThoracic Cyclone BGi Inc Waltham MA) placed in the employees breathing zone (NIOSH 1994 HSE 1997)

Area samples were collected on both days of sampling at six locations on the millng instruments mounted on a metal frame (Figure 4) Themachine using an aray of

platform near the level controls onlocations included the dashboard on the operators

both sides of the mil near the cutter dr on both sides of the mil and on the right side

conveyor to the loading conveyor (Figure 5) The sampling intruments in each aray included a Ii ght-scattering aerosol photometer (pDR near the transition from the primary

Theano Electron Corp Franklin MA) with a 10 millmeter (mm) nylon cyclone comiected to the inlet via flexible tubing The pDR was in tur connected via flexible tubing to a battery-operated sampling pump calibrated at a flow rate of 17 Llmin A pre-weighed 5-~m pore-size polyvinyl chloride filter supported by a backup pad in a two-piece filter cassette sealed with a cellulose shr band was placed in line between the

5

pDR and the pump Also included in each sampling aray were two battery-operated sampling pumps both connected though flexible tubing to a 10-mm nylon cyclone and a pre-weighed 37-mm diameter 5-iexclm pore-size polyvnyl chloride filter supported by a backup pad in a two-piece filter cassette sealed with a cellulose shn band in accordance with NIOSH Methods 0600 and 7500

On the second day of sampling addigravetional area sauiples were collected at the six locations described above at a flow rate of 42 litersminute using a battery-operated sampling pump connected via flexible tubing to a pre-weighed 37-mm diameter 5shymicron (iexclm) pore-size polyvinyl chloride filter supported by a backup pad in a three-piece fiter cassette sealed with a cellulose shrink band in accordance with NIOSH Methods 0600 and 7500 and a cyclone (OK 269 RespirableThoracic Cyclone BGI Inc Waltham MA) attached to the metal frame

Gravimetric analysis for respirable pariculate was cared out with the fOllOWing modifications to NIOSH Method 0600 1) the fiters and backup pads were stored in an environmentally controlled room (201 1degC and 50i5 relative humidity) and were subj ected to the room conditions for at least two hours for stabilization prior to tare and gross weighing and 2) two weighings of the tare weight and gross weight were performed (NIOSH 1994) The difference between the average gross weight and the average tare weight was the result of the analysis The limit of detection for this method was 002 mg

Crystalline silica analysis ofthehigravegher-flow fiter and all bulk samples was perfornied using X-ray diffraction NIOSHMethod 7500 was used ith the following modifications 1) fiters were dissolved in tetraIgraveydrofurail rather than being ashed in a furace and 2) standards and samples were run concurently and an external calibration ciire was prepared from the integrated intensities rather than using the suggested normalization procedure (NIOSH 1994) These samples were analyzed for quarz and cristobalite The limits of detection for quarz and cristobalite on filters were 001 and 002 mg respectively The limit of quantiation is 003 mg for both quarz and cristobalite The lower-flow filter samples were not analyzed for silica

bulk samples collected from miled pavement left in or next to the cut by the millng machine The limit of detection for quar in bulk samples was 08 The limit of quantitation was 2

The silica content of the pavement was determined though testing of

Experimental design

Initial activities on site such as installing new water spray nozzles and new cutter-drm teeth were devoted to returing the mil to the manufacturers specifications DulIgraveng the

first day of sampling samples were collected over thee sampliacuteng periods during a typical miling job The second day of sampling was divided into four 2-hour periods During

the first period the manufacturer-specified nozzles (UniJetll model1 005 SS Spraying Systems Co Wheaton IL) rated at 05 gallons per minute (gpm) at 40 pounds per square

6

inch (psi) were used For the second and thd period higher-flow nozzles CUniJ etQI

model 11008 Spraying System Co Wheaton IL) rated at 08 gpm at 40 psi were installed on the cutter-dr spray bar Durng the final period the manufactuershy

specified nozzles were used again This design was used instead of a randomized design because of the length of time and effort required to change the nozzles in the field The spray nozzles for the primar conveyor and the material transfer conveyor were not changed Personal and high-flow area samples for respirable dust and respirable crystallne silica were changed approximately every two hours durig both sampling days The lower-flow area samples were collected for the full shift on both days

RESULTS AND DISCUSSION

Description of the Mil and the Controls

The miling machine used at this site had 3560 hours on the machine at the beginnng of the site visit It was equipped with water spray nozzles at three places including dr spraying nozzles primar conveyor spraying nozzles and material transfer conveying nozzles There were 18 flat fan spray nozzles (UniJetQI model 11005 SS Spraying Systems Co Wheaton IL) mounted on a spragravey bar in the cutter dru housing This type

of nozzle was used at all of the installations on this milL Thegrave fist thee nozzles on the cutter dr spray bar were mounted 2 inches (in) apar the thrd and fourh nozzle were

mounted 3 in apar and the remaining nozzles were 5 Yi in apar The cutter dr

extension was served by a separate spray bar equipped with thee nozzles The first two nozzles were 2in apar while the second and thrd nozzle were 5 Yi in apar There were a total of nine nozzles at the primary conveyor installed at the transition from the cutter dr to the primar conveyor four were mounted on each side and one on the extension

These nozzles were 1 foot apar There were two nozzles mounted above the material transfer conveyor at the transition from the primar cogravenveyor Those nozzles were 32 in apar New nozzles were installed on the evening before the first sampling day The water pump for the spraying system is rated at 40 Llmin (106 gallons) of water at 3 Yi bar (51 psi)

The 8 ft 6 in wide cutter dr held 193 bits aranged in a helical coil around the dr

holders were in factory spec condition with 50 hrs on the holders NewThe drm and

bits were installed on the evening before the first sampling day and were changed several times durg the next two days The dr rotation was measured and found to agree with

the manufacturers specification of928 rpm

Personal protective equipment and work practices

The miling crew members wore hard hats (except the operator) safety glasses and traffc safety vests The operator was the only employee who spent all of his time on the mil operating the mil from either the right or left side of the operators station The foreman spent the majority of the first day operatig the rear controls while the thid ecircrewman performed tasks such as operating a skid-steer loader and drvig the water

7

in the afternoon the foreman operated the skid steer loader while the third crewman ran the rear controls For the most par the skid-steer loader was not operated near the miling machine on the first day On one occasion a road grader passed by and for a brief period in the afternoon nugravellig took place alongside a field while a farer was running a combine On the second day the skid-steer loader

truck (Figure 6) However

the daythe day and the third crew member spent most ofwas idle for the majority of

the rear controls The foreman left the migravelperiodically to attend torunning one of

matters such as trck scheduling On both days the trcks assigned to take away thepossiblethe road unti that was no longermiled material drove on the paved portion of

lessening the potential of dust being generated by the trucks as they passed the millng machine

Respirable dust and crystallne silica sampling results

personal breathing zone sampling for respirable dust and crystalline silica conducted on October 8 are presented in Table 1 On October 8 which represented a typical millng day respirable dust results ranged from 014 to 183 mgm The TW A respirable dust exposures for the three employees were 026 mgmJ (499 minutes) for the

The results of

operator 10 mgm3 (495 minutes) for the foreman and 038 mgm3 (438 minutes) for the third employee who began the day operatin~ the skid steer loader Their 8-hour TWAs were 027 mgm3 for the operator 10 mgm for the foreman and 035 mgm3 for the third crew member The OSHA PELs for these employees calculated based upon the percent silica in their samples were 142 mgm 3 for the operator 117 mgm3 for the foreman and 113 mgm3 for the third member of the miling crew The PELs were calculated using the value of the LODJ for quarz values below the LOD (Hornung and Reed 1990) None of the employees exposures exceeded the OSHA PEL on October 8 as a TW A but excursions above the PEL did take place during the first two sampling periods for the foreman who spent most of those periods operating the rear controls on the mUL

Respirable quarz results from personal samples ranged from below the limit of to

detection 01 1 inglm3 The TW A respirable quarz exposures for October 8 were 0013 mgm3 for the operator 0064 mgm3 for the foreman and 0030 mgm3 for the third

LOD formiling Crew member The TWAs were also calculated using the value of

001 mg Their 8-hour quartz TWAs were 0014 mgm3 0066 mglm3 and 0027 mgm3 respectively On October 8 the foremans TWA and 8-hour TWA exposure exceeded the NIOSH quarz REL of 005 nigm3

quarz results less than the LOD of

the milling crews respirable dust and respirable quartzTable 2 lists the results of

exposures by nozzle type and employee results in TWAs of21 mgm3 for the operator 062 mgm3 for the foreman and 11 mgm3 for the rear control operator for the UniJ etfI 11005 nozzle versus 14 mglm3 065 mgm3 and 089 mgm respectively forthe UniJetaeligl 11008 nozzle TWA

samples on October 9 Calculating TWA respirable dust

the operator 0041

mgm3 for the foreman and 0050 mgin3 for the worker operating the rear controls quartz results for the UniJetfI 11005 nozzle were 012 mgm3 for

8

0081 mgm3 for the operator TW A quarz results for the UniacuteJetlIII008 nozzle were

0041 mgm3 for the foreman and 0043 mgm3 for the thrd crewman In contrast to October 8 the operator received the highest exposures on the second sampling day

Table 3 shows that the highest emissionsthe nozzle type Inspection ofregardless of

side of the mil and the upper conveyor Unfortunately the weather station did not log data so the effect of the wind direction on those results is unnown

were associated with the left

the area samplescoUected on October 8 with the lower-flow respirable dust samplers (17 Lmin) and the pdR direct-reading instruments Those results indicate that for both sampling methods that exposures were lowest igraven the

Table 4 reports the results of

operators station and highest at the upper conveyor (the material transfer conveyor) This table also lists the gravimetricpDR ratios calculated for each sampling location These ratios were used to adjust pDR short teimsampling concentrations which are provided later in ths report Table 5 presents the results for the lower-flow respirable

dust samples and the pdR samples for October 9 including the results from all nozzle types The upper conveyor produced the highest exposure on that day as welL Perhaps the operators personal exposures differ from the area sample at his work station because

the time on one or the other side of the mm while the sampler was in the

he spends most of

his work station (Figure 7) Table 5 which provides the results ofthe center of

lower-flow andpdR area samples shows that as in Table 3 the highest emissions were associated with the left side of the mill and the upper conveyor The migraveU removed

the road so the left side oftlie mm was facing the pavedmaterial from the right side of

the road while the right side faced the previous cut This orientation may explain the milL The manufacturers

edge of

in par why the exposures were higher on the left side of

6 relates area samplingrepresentative attributed this result to passing truck trame Table

results to productivity water flow and water spray pressure while Table 7 describes the work done on October 9

When reviewing the results of sampling conducted on October 9 for the purpose of this study it is useful to compare the results obtained when the different water spray nozzles

logwere used For the purpose ofthisaualysis the results were converted to the natural

the data did not vary with(In) scale because on the log scale the varabmty of

concentration From the In scale analysis of the respirable dust results (Tables 8~ II) the ratio of the UniJ etlf 11005 nozzle to the DniJ et(szlig i 1008 nozzle results is the ratio of their geometric means 12 This indicates that the respirable dust measurements obtained

are about 20 higher thotigh the result is not statistically significant even at the lO signifcance leveL Results for the pDRs are while the UniJetlf 11005 nozzle was used

also about 20 higher for the UnijetQ 11005 and are also notsimilar Those results are

statistically significant at the 10 leveL Examination oftbe tables indicates that for mostthe

groupings the UniJetlIl1005 nozzle does give higher results Review of all of

the UniacuteJet(( 11005 nozzle resultsrespirable dust data from October 9 shows that 59 of

exceeded the PEL while 50 of the UniJetI 11008 nozzle results did so For personal breathing zone samples half of the results while the Unijet(szlig 11005 was in use exceeded

the UnijetlI 11008 results exceeded the PELthe PEL one third of

9

From the In scale analysis of the quarz samplig results (Tables 12-15) the ratio of the Uniet(szlig 11005 nozzle to the Uniet(szlig 11008 nozzle results is the ratio of their geometrc means 116 Thus for respirable quar the results while Uniet(szlig i 1005 nozzles were intalled on the cutter drm were about 16 higher though the result is not statisticaly signficant even at the 10 signcance leveL Examation of the tables indicates that the quar results are not as consistent as those for respirable dust For data from both days 7 respirable quar results were less than the LOD and 13 values were between LOD and LOQ For the seven quarz values below the LOD the value Lan was substituted

Quarz in bulk samples

The results of 10 bulk samples ranged from 12 to 28 with a mean of 199 and a median of 185

CONCLUSIONS AN RECOMMNDATIONS

Conclusions from ths pilot study regardig the effect of increasing the water flow to the spray nozzles on dust and quart exposures are lited by several factors First the higher flow nozzles were only intalled on the cutter dr and the cutter dr extension

the nozzles selected represent a difference of only 30 more flow when the higher-flow nozzles were installed Nevereless the respirable dust measurements obtaied while the Uniet(szlig 11005 nozzles were used were about 20 higher than when the higher-flow Uniet(szlig 11008 nozzles were used The respirable quarz results while Uniet(szlig 11005 nozzles were installed on the cutter dr were about 16 higher Neither

Second

the reductions in respirable dust concentrations nor those for the quarz results were statistically signficant even at the lO signficance leveL Statistical signficance mean that the difference is not due to chance alone

Research on dust controls in minig has shown that water sprays have two roles wetting of broken material being transported and airborne captue (NOSH 2003) Uniformly wetting the broken material durg the breakage process is far more effective and enures that dust paricles stay attached to the materal (NQSH 2003) Increasing the water flow rate and increasing the number of sprays have both been shown to be effective it is tooearly in this proj ect to recommend an approach In one inance dust from a shearer dr was reduced by 60 when the 46 smaler orifice nozzles were substituted for the originall7 nozzles with the pressure and flow held constant (NOSH 2003) The shape of the spray is another importnt factor in its effectveness

Futue studies might test the water system on a newer-model machie to begi to explore the relationship between water flow and pressue agravend aiborne dust concentrtions Varables related to the site andjob might obscure ths relationship but it is hoped that a trend might emerge

10

REFERENCES

29 CFR 19101000 (2001) Occupational Safety and Health Admstration air

containants

29 CFR 192655 (2003) Occupational Safety and Health Adminstration gases vapors fues dusts and mists

ACGrn (2004) Theshold limit values for chemical substances CincinatiOH American Conference of Governental Industral Hygienists

Akbar-Khanadeh F Brillhar RL (2002) Respirable crystallne silca dust exposure durng concrete finshing (grnding) using hand-held grnders in the constrction industr An occup Hyg 46341-346

Bureau of Mines (1992) Crystallne silica primer Washigton DC US Deparent of the Interior Bureau of Mines Branch of Industral Minerals Special Publication

Glindmeyer HW Hamad YY (1988) Contributing factors to sandblasters silcosis inadequate respiratory protection equipment and standards J accup Med 30917-921

HSE (1997) MDHS 142 General methods for sampling and gravimetrc analysis of respirable and total inhalable dust Methods for the determination of hazardous substances lIealth and safety laboratory Sudbur Suffolk UK Health and Safety Executive

Homuug R Reed L (1990) Estimation of average concentration in the presence of nondetectable values Applied Occupational and Environmental Hygiene 5(1)46-51

Linch KD (2002) Respirable concrete dust-silcosis hazard in the constrction industr

Appl Occup and Environ Hyg 17 209-221

Neuhauser Curt (curneuhauser(ecircdotstatewius) (2004) RE US 12 project Private e-mail message to Alan Echt (AEcht(ecirccdcgov) Januar 7

New Jersey Deparent of Health and Senior Services (2001) New Jersey silica parership In Occupational Health Sureilance Update February Trenton NJ NJ

Deparment of Health and Senior Services Division of Epidemiology Environmental and Occupational Health Occupational Health Service Occupational Health Sureilance Program

11

observing and recording the foot speed reading on the intrent panel ofthe mil every two minutes As a measure recorded durng both days of miling by a NIOSH researcher

of productivity the time was recorded when each dump truck was loaded and pulled away from the millng machine

Depth of cut was measurecl every fifteen minutes during both milling days using a tape measure helcl at the edge of the cut pavement The width of the cut was measured as well Bulk samples of the miled pavement were collected on a periodic basis from

left in or next to the cut by the milling machine Wind speed and direction and temperature were recorded usigraveng a data-loggigraveug weather station (MultiLog Weather material

Station Fourier Systems Inc Atlanta GA) A hand-held muitigrave~directional impeller wind meter was also used during the survey (Skywatch Meteos JDC Electronic SA Yverdon-Ies-Bains Switzerland)

The work practices and use of personal protective equipment were recorded for each worker sampled including the workers position and distance relative to the miling machine (eg walking alongside following behind riding) Infomiation obtained from conversations with worlcers to detennine if the sampling days were typical of the nomial work load helped to place the sampling results in proper perspective Data were recorded describing other operations nearby that generated dust including the process its location relatIacuteve to the miling machine and whether it was upwind or downwind of the millng machine

Dust and Silca Sampling Methods

On both days of sampling personal breathing zone samples on the three members of the miling crew were collected at a flow rate of 42 liters per minute (Umin) using a battery-operated sampling pump at the employees waist connected via flexible tubing to a pre-weighed 37-mm diameter 5-micron (~m) pore-size polyvinyl chloride filter supported by a backup pad in a three-piece filter cassette sealed with a cellulose shrink band in accordance with NIOSH Methods 0600 and 7500 and a cyclone (GK 269 RespirableThoracic Cyclone BGi Inc Waltham MA) placed in the employees breathing zone (NIOSH 1994 HSE 1997)

Area samples were collected on both days of sampling at six locations on the millng instruments mounted on a metal frame (Figure 4) Themachine using an aray of

platform near the level controls onlocations included the dashboard on the operators

both sides of the mil near the cutter dr on both sides of the mil and on the right side

conveyor to the loading conveyor (Figure 5) The sampling intruments in each aray included a Ii ght-scattering aerosol photometer (pDR near the transition from the primary

Theano Electron Corp Franklin MA) with a 10 millmeter (mm) nylon cyclone comiected to the inlet via flexible tubing The pDR was in tur connected via flexible tubing to a battery-operated sampling pump calibrated at a flow rate of 17 Llmin A pre-weighed 5-~m pore-size polyvinyl chloride filter supported by a backup pad in a two-piece filter cassette sealed with a cellulose shr band was placed in line between the

5

pDR and the pump Also included in each sampling aray were two battery-operated sampling pumps both connected though flexible tubing to a 10-mm nylon cyclone and a pre-weighed 37-mm diameter 5-iexclm pore-size polyvnyl chloride filter supported by a backup pad in a two-piece filter cassette sealed with a cellulose shn band in accordance with NIOSH Methods 0600 and 7500

On the second day of sampling addigravetional area sauiples were collected at the six locations described above at a flow rate of 42 litersminute using a battery-operated sampling pump connected via flexible tubing to a pre-weighed 37-mm diameter 5shymicron (iexclm) pore-size polyvinyl chloride filter supported by a backup pad in a three-piece fiter cassette sealed with a cellulose shrink band in accordance with NIOSH Methods 0600 and 7500 and a cyclone (OK 269 RespirableThoracic Cyclone BGI Inc Waltham MA) attached to the metal frame

Gravimetric analysis for respirable pariculate was cared out with the fOllOWing modifications to NIOSH Method 0600 1) the fiters and backup pads were stored in an environmentally controlled room (201 1degC and 50i5 relative humidity) and were subj ected to the room conditions for at least two hours for stabilization prior to tare and gross weighing and 2) two weighings of the tare weight and gross weight were performed (NIOSH 1994) The difference between the average gross weight and the average tare weight was the result of the analysis The limit of detection for this method was 002 mg

Crystalline silica analysis ofthehigravegher-flow fiter and all bulk samples was perfornied using X-ray diffraction NIOSHMethod 7500 was used ith the following modifications 1) fiters were dissolved in tetraIgraveydrofurail rather than being ashed in a furace and 2) standards and samples were run concurently and an external calibration ciire was prepared from the integrated intensities rather than using the suggested normalization procedure (NIOSH 1994) These samples were analyzed for quarz and cristobalite The limits of detection for quarz and cristobalite on filters were 001 and 002 mg respectively The limit of quantiation is 003 mg for both quarz and cristobalite The lower-flow filter samples were not analyzed for silica

bulk samples collected from miled pavement left in or next to the cut by the millng machine The limit of detection for quar in bulk samples was 08 The limit of quantitation was 2

The silica content of the pavement was determined though testing of

Experimental design

Initial activities on site such as installing new water spray nozzles and new cutter-drm teeth were devoted to returing the mil to the manufacturers specifications DulIgraveng the

first day of sampling samples were collected over thee sampliacuteng periods during a typical miling job The second day of sampling was divided into four 2-hour periods During

the first period the manufacturer-specified nozzles (UniJetll model1 005 SS Spraying Systems Co Wheaton IL) rated at 05 gallons per minute (gpm) at 40 pounds per square

6

inch (psi) were used For the second and thd period higher-flow nozzles CUniJ etQI

model 11008 Spraying System Co Wheaton IL) rated at 08 gpm at 40 psi were installed on the cutter-dr spray bar Durng the final period the manufactuershy

specified nozzles were used again This design was used instead of a randomized design because of the length of time and effort required to change the nozzles in the field The spray nozzles for the primar conveyor and the material transfer conveyor were not changed Personal and high-flow area samples for respirable dust and respirable crystallne silica were changed approximately every two hours durig both sampling days The lower-flow area samples were collected for the full shift on both days

RESULTS AND DISCUSSION

Description of the Mil and the Controls

The miling machine used at this site had 3560 hours on the machine at the beginnng of the site visit It was equipped with water spray nozzles at three places including dr spraying nozzles primar conveyor spraying nozzles and material transfer conveying nozzles There were 18 flat fan spray nozzles (UniJetQI model 11005 SS Spraying Systems Co Wheaton IL) mounted on a spragravey bar in the cutter dru housing This type

of nozzle was used at all of the installations on this milL Thegrave fist thee nozzles on the cutter dr spray bar were mounted 2 inches (in) apar the thrd and fourh nozzle were

mounted 3 in apar and the remaining nozzles were 5 Yi in apar The cutter dr

extension was served by a separate spray bar equipped with thee nozzles The first two nozzles were 2in apar while the second and thrd nozzle were 5 Yi in apar There were a total of nine nozzles at the primary conveyor installed at the transition from the cutter dr to the primar conveyor four were mounted on each side and one on the extension

These nozzles were 1 foot apar There were two nozzles mounted above the material transfer conveyor at the transition from the primar cogravenveyor Those nozzles were 32 in apar New nozzles were installed on the evening before the first sampling day The water pump for the spraying system is rated at 40 Llmin (106 gallons) of water at 3 Yi bar (51 psi)

The 8 ft 6 in wide cutter dr held 193 bits aranged in a helical coil around the dr

holders were in factory spec condition with 50 hrs on the holders NewThe drm and

bits were installed on the evening before the first sampling day and were changed several times durg the next two days The dr rotation was measured and found to agree with

the manufacturers specification of928 rpm

Personal protective equipment and work practices

The miling crew members wore hard hats (except the operator) safety glasses and traffc safety vests The operator was the only employee who spent all of his time on the mil operating the mil from either the right or left side of the operators station The foreman spent the majority of the first day operatig the rear controls while the thid ecircrewman performed tasks such as operating a skid-steer loader and drvig the water

7

in the afternoon the foreman operated the skid steer loader while the third crewman ran the rear controls For the most par the skid-steer loader was not operated near the miling machine on the first day On one occasion a road grader passed by and for a brief period in the afternoon nugravellig took place alongside a field while a farer was running a combine On the second day the skid-steer loader

truck (Figure 6) However

the daythe day and the third crew member spent most ofwas idle for the majority of

the rear controls The foreman left the migravelperiodically to attend torunning one of

matters such as trck scheduling On both days the trcks assigned to take away thepossiblethe road unti that was no longermiled material drove on the paved portion of

lessening the potential of dust being generated by the trucks as they passed the millng machine

Respirable dust and crystallne silica sampling results

personal breathing zone sampling for respirable dust and crystalline silica conducted on October 8 are presented in Table 1 On October 8 which represented a typical millng day respirable dust results ranged from 014 to 183 mgm The TW A respirable dust exposures for the three employees were 026 mgmJ (499 minutes) for the

The results of

operator 10 mgm3 (495 minutes) for the foreman and 038 mgm3 (438 minutes) for the third employee who began the day operatin~ the skid steer loader Their 8-hour TWAs were 027 mgm3 for the operator 10 mgm for the foreman and 035 mgm3 for the third crew member The OSHA PELs for these employees calculated based upon the percent silica in their samples were 142 mgm 3 for the operator 117 mgm3 for the foreman and 113 mgm3 for the third member of the miling crew The PELs were calculated using the value of the LODJ for quarz values below the LOD (Hornung and Reed 1990) None of the employees exposures exceeded the OSHA PEL on October 8 as a TW A but excursions above the PEL did take place during the first two sampling periods for the foreman who spent most of those periods operating the rear controls on the mUL

Respirable quarz results from personal samples ranged from below the limit of to

detection 01 1 inglm3 The TW A respirable quarz exposures for October 8 were 0013 mgm3 for the operator 0064 mgm3 for the foreman and 0030 mgm3 for the third

LOD formiling Crew member The TWAs were also calculated using the value of

001 mg Their 8-hour quartz TWAs were 0014 mgm3 0066 mglm3 and 0027 mgm3 respectively On October 8 the foremans TWA and 8-hour TWA exposure exceeded the NIOSH quarz REL of 005 nigm3

quarz results less than the LOD of

the milling crews respirable dust and respirable quartzTable 2 lists the results of

exposures by nozzle type and employee results in TWAs of21 mgm3 for the operator 062 mgm3 for the foreman and 11 mgm3 for the rear control operator for the UniJ etfI 11005 nozzle versus 14 mglm3 065 mgm3 and 089 mgm respectively forthe UniJetaeligl 11008 nozzle TWA

samples on October 9 Calculating TWA respirable dust

the operator 0041

mgm3 for the foreman and 0050 mgin3 for the worker operating the rear controls quartz results for the UniJetfI 11005 nozzle were 012 mgm3 for

8

0081 mgm3 for the operator TW A quarz results for the UniacuteJetlIII008 nozzle were

0041 mgm3 for the foreman and 0043 mgm3 for the thrd crewman In contrast to October 8 the operator received the highest exposures on the second sampling day

Table 3 shows that the highest emissionsthe nozzle type Inspection ofregardless of

side of the mil and the upper conveyor Unfortunately the weather station did not log data so the effect of the wind direction on those results is unnown

were associated with the left

the area samplescoUected on October 8 with the lower-flow respirable dust samplers (17 Lmin) and the pdR direct-reading instruments Those results indicate that for both sampling methods that exposures were lowest igraven the

Table 4 reports the results of

operators station and highest at the upper conveyor (the material transfer conveyor) This table also lists the gravimetricpDR ratios calculated for each sampling location These ratios were used to adjust pDR short teimsampling concentrations which are provided later in ths report Table 5 presents the results for the lower-flow respirable

dust samples and the pdR samples for October 9 including the results from all nozzle types The upper conveyor produced the highest exposure on that day as welL Perhaps the operators personal exposures differ from the area sample at his work station because

the time on one or the other side of the mm while the sampler was in the

he spends most of

his work station (Figure 7) Table 5 which provides the results ofthe center of

lower-flow andpdR area samples shows that as in Table 3 the highest emissions were associated with the left side of the mill and the upper conveyor The migraveU removed

the road so the left side oftlie mm was facing the pavedmaterial from the right side of

the road while the right side faced the previous cut This orientation may explain the milL The manufacturers

edge of

in par why the exposures were higher on the left side of

6 relates area samplingrepresentative attributed this result to passing truck trame Table

results to productivity water flow and water spray pressure while Table 7 describes the work done on October 9

When reviewing the results of sampling conducted on October 9 for the purpose of this study it is useful to compare the results obtained when the different water spray nozzles

logwere used For the purpose ofthisaualysis the results were converted to the natural

the data did not vary with(In) scale because on the log scale the varabmty of

concentration From the In scale analysis of the respirable dust results (Tables 8~ II) the ratio of the UniJ etlf 11005 nozzle to the DniJ et(szlig i 1008 nozzle results is the ratio of their geometric means 12 This indicates that the respirable dust measurements obtained

are about 20 higher thotigh the result is not statistically significant even at the lO signifcance leveL Results for the pDRs are while the UniJetlf 11005 nozzle was used

also about 20 higher for the UnijetQ 11005 and are also notsimilar Those results are

statistically significant at the 10 leveL Examination oftbe tables indicates that for mostthe

groupings the UniJetlIl1005 nozzle does give higher results Review of all of

the UniacuteJet(( 11005 nozzle resultsrespirable dust data from October 9 shows that 59 of

exceeded the PEL while 50 of the UniJetI 11008 nozzle results did so For personal breathing zone samples half of the results while the Unijet(szlig 11005 was in use exceeded

the UnijetlI 11008 results exceeded the PELthe PEL one third of

9

From the In scale analysis of the quarz samplig results (Tables 12-15) the ratio of the Uniet(szlig 11005 nozzle to the Uniet(szlig 11008 nozzle results is the ratio of their geometrc means 116 Thus for respirable quar the results while Uniet(szlig i 1005 nozzles were intalled on the cutter drm were about 16 higher though the result is not statisticaly signficant even at the 10 signcance leveL Examation of the tables indicates that the quar results are not as consistent as those for respirable dust For data from both days 7 respirable quar results were less than the LOD and 13 values were between LOD and LOQ For the seven quarz values below the LOD the value Lan was substituted

Quarz in bulk samples

The results of 10 bulk samples ranged from 12 to 28 with a mean of 199 and a median of 185

CONCLUSIONS AN RECOMMNDATIONS

Conclusions from ths pilot study regardig the effect of increasing the water flow to the spray nozzles on dust and quart exposures are lited by several factors First the higher flow nozzles were only intalled on the cutter dr and the cutter dr extension

the nozzles selected represent a difference of only 30 more flow when the higher-flow nozzles were installed Nevereless the respirable dust measurements obtaied while the Uniet(szlig 11005 nozzles were used were about 20 higher than when the higher-flow Uniet(szlig 11008 nozzles were used The respirable quarz results while Uniet(szlig 11005 nozzles were installed on the cutter dr were about 16 higher Neither

Second

the reductions in respirable dust concentrations nor those for the quarz results were statistically signficant even at the lO signficance leveL Statistical signficance mean that the difference is not due to chance alone

Research on dust controls in minig has shown that water sprays have two roles wetting of broken material being transported and airborne captue (NOSH 2003) Uniformly wetting the broken material durg the breakage process is far more effective and enures that dust paricles stay attached to the materal (NQSH 2003) Increasing the water flow rate and increasing the number of sprays have both been shown to be effective it is tooearly in this proj ect to recommend an approach In one inance dust from a shearer dr was reduced by 60 when the 46 smaler orifice nozzles were substituted for the originall7 nozzles with the pressure and flow held constant (NOSH 2003) The shape of the spray is another importnt factor in its effectveness

Futue studies might test the water system on a newer-model machie to begi to explore the relationship between water flow and pressue agravend aiborne dust concentrtions Varables related to the site andjob might obscure ths relationship but it is hoped that a trend might emerge

10

REFERENCES

29 CFR 19101000 (2001) Occupational Safety and Health Admstration air

containants

29 CFR 192655 (2003) Occupational Safety and Health Adminstration gases vapors fues dusts and mists

ACGrn (2004) Theshold limit values for chemical substances CincinatiOH American Conference of Governental Industral Hygienists

Akbar-Khanadeh F Brillhar RL (2002) Respirable crystallne silca dust exposure durng concrete finshing (grnding) using hand-held grnders in the constrction industr An occup Hyg 46341-346

Bureau of Mines (1992) Crystallne silica primer Washigton DC US Deparent of the Interior Bureau of Mines Branch of Industral Minerals Special Publication

Glindmeyer HW Hamad YY (1988) Contributing factors to sandblasters silcosis inadequate respiratory protection equipment and standards J accup Med 30917-921

HSE (1997) MDHS 142 General methods for sampling and gravimetrc analysis of respirable and total inhalable dust Methods for the determination of hazardous substances lIealth and safety laboratory Sudbur Suffolk UK Health and Safety Executive

Homuug R Reed L (1990) Estimation of average concentration in the presence of nondetectable values Applied Occupational and Environmental Hygiene 5(1)46-51

Linch KD (2002) Respirable concrete dust-silcosis hazard in the constrction industr

Appl Occup and Environ Hyg 17 209-221

Neuhauser Curt (curneuhauser(ecircdotstatewius) (2004) RE US 12 project Private e-mail message to Alan Echt (AEcht(ecirccdcgov) Januar 7

New Jersey Deparent of Health and Senior Services (2001) New Jersey silica parership In Occupational Health Sureilance Update February Trenton NJ NJ

Deparment of Health and Senior Services Division of Epidemiology Environmental and Occupational Health Occupational Health Service Occupational Health Sureilance Program

11

pDR and the pump Also included in each sampling aray were two battery-operated sampling pumps both connected though flexible tubing to a 10-mm nylon cyclone and a pre-weighed 37-mm diameter 5-iexclm pore-size polyvnyl chloride filter supported by a backup pad in a two-piece filter cassette sealed with a cellulose shn band in accordance with NIOSH Methods 0600 and 7500

On the second day of sampling addigravetional area sauiples were collected at the six locations described above at a flow rate of 42 litersminute using a battery-operated sampling pump connected via flexible tubing to a pre-weighed 37-mm diameter 5shymicron (iexclm) pore-size polyvinyl chloride filter supported by a backup pad in a three-piece fiter cassette sealed with a cellulose shrink band in accordance with NIOSH Methods 0600 and 7500 and a cyclone (OK 269 RespirableThoracic Cyclone BGI Inc Waltham MA) attached to the metal frame

Gravimetric analysis for respirable pariculate was cared out with the fOllOWing modifications to NIOSH Method 0600 1) the fiters and backup pads were stored in an environmentally controlled room (201 1degC and 50i5 relative humidity) and were subj ected to the room conditions for at least two hours for stabilization prior to tare and gross weighing and 2) two weighings of the tare weight and gross weight were performed (NIOSH 1994) The difference between the average gross weight and the average tare weight was the result of the analysis The limit of detection for this method was 002 mg

Crystalline silica analysis ofthehigravegher-flow fiter and all bulk samples was perfornied using X-ray diffraction NIOSHMethod 7500 was used ith the following modifications 1) fiters were dissolved in tetraIgraveydrofurail rather than being ashed in a furace and 2) standards and samples were run concurently and an external calibration ciire was prepared from the integrated intensities rather than using the suggested normalization procedure (NIOSH 1994) These samples were analyzed for quarz and cristobalite The limits of detection for quarz and cristobalite on filters were 001 and 002 mg respectively The limit of quantiation is 003 mg for both quarz and cristobalite The lower-flow filter samples were not analyzed for silica

bulk samples collected from miled pavement left in or next to the cut by the millng machine The limit of detection for quar in bulk samples was 08 The limit of quantitation was 2

The silica content of the pavement was determined though testing of

Experimental design

Initial activities on site such as installing new water spray nozzles and new cutter-drm teeth were devoted to returing the mil to the manufacturers specifications DulIgraveng the

first day of sampling samples were collected over thee sampliacuteng periods during a typical miling job The second day of sampling was divided into four 2-hour periods During

the first period the manufacturer-specified nozzles (UniJetll model1 005 SS Spraying Systems Co Wheaton IL) rated at 05 gallons per minute (gpm) at 40 pounds per square

6

inch (psi) were used For the second and thd period higher-flow nozzles CUniJ etQI

model 11008 Spraying System Co Wheaton IL) rated at 08 gpm at 40 psi were installed on the cutter-dr spray bar Durng the final period the manufactuershy

specified nozzles were used again This design was used instead of a randomized design because of the length of time and effort required to change the nozzles in the field The spray nozzles for the primar conveyor and the material transfer conveyor were not changed Personal and high-flow area samples for respirable dust and respirable crystallne silica were changed approximately every two hours durig both sampling days The lower-flow area samples were collected for the full shift on both days

RESULTS AND DISCUSSION

Description of the Mil and the Controls

The miling machine used at this site had 3560 hours on the machine at the beginnng of the site visit It was equipped with water spray nozzles at three places including dr spraying nozzles primar conveyor spraying nozzles and material transfer conveying nozzles There were 18 flat fan spray nozzles (UniJetQI model 11005 SS Spraying Systems Co Wheaton IL) mounted on a spragravey bar in the cutter dru housing This type

of nozzle was used at all of the installations on this milL Thegrave fist thee nozzles on the cutter dr spray bar were mounted 2 inches (in) apar the thrd and fourh nozzle were

mounted 3 in apar and the remaining nozzles were 5 Yi in apar The cutter dr

extension was served by a separate spray bar equipped with thee nozzles The first two nozzles were 2in apar while the second and thrd nozzle were 5 Yi in apar There were a total of nine nozzles at the primary conveyor installed at the transition from the cutter dr to the primar conveyor four were mounted on each side and one on the extension

These nozzles were 1 foot apar There were two nozzles mounted above the material transfer conveyor at the transition from the primar cogravenveyor Those nozzles were 32 in apar New nozzles were installed on the evening before the first sampling day The water pump for the spraying system is rated at 40 Llmin (106 gallons) of water at 3 Yi bar (51 psi)

The 8 ft 6 in wide cutter dr held 193 bits aranged in a helical coil around the dr

holders were in factory spec condition with 50 hrs on the holders NewThe drm and

bits were installed on the evening before the first sampling day and were changed several times durg the next two days The dr rotation was measured and found to agree with

the manufacturers specification of928 rpm

Personal protective equipment and work practices

The miling crew members wore hard hats (except the operator) safety glasses and traffc safety vests The operator was the only employee who spent all of his time on the mil operating the mil from either the right or left side of the operators station The foreman spent the majority of the first day operatig the rear controls while the thid ecircrewman performed tasks such as operating a skid-steer loader and drvig the water

7

in the afternoon the foreman operated the skid steer loader while the third crewman ran the rear controls For the most par the skid-steer loader was not operated near the miling machine on the first day On one occasion a road grader passed by and for a brief period in the afternoon nugravellig took place alongside a field while a farer was running a combine On the second day the skid-steer loader

truck (Figure 6) However

the daythe day and the third crew member spent most ofwas idle for the majority of

the rear controls The foreman left the migravelperiodically to attend torunning one of

matters such as trck scheduling On both days the trcks assigned to take away thepossiblethe road unti that was no longermiled material drove on the paved portion of

lessening the potential of dust being generated by the trucks as they passed the millng machine

Respirable dust and crystallne silica sampling results

personal breathing zone sampling for respirable dust and crystalline silica conducted on October 8 are presented in Table 1 On October 8 which represented a typical millng day respirable dust results ranged from 014 to 183 mgm The TW A respirable dust exposures for the three employees were 026 mgmJ (499 minutes) for the

The results of

operator 10 mgm3 (495 minutes) for the foreman and 038 mgm3 (438 minutes) for the third employee who began the day operatin~ the skid steer loader Their 8-hour TWAs were 027 mgm3 for the operator 10 mgm for the foreman and 035 mgm3 for the third crew member The OSHA PELs for these employees calculated based upon the percent silica in their samples were 142 mgm 3 for the operator 117 mgm3 for the foreman and 113 mgm3 for the third member of the miling crew The PELs were calculated using the value of the LODJ for quarz values below the LOD (Hornung and Reed 1990) None of the employees exposures exceeded the OSHA PEL on October 8 as a TW A but excursions above the PEL did take place during the first two sampling periods for the foreman who spent most of those periods operating the rear controls on the mUL

Respirable quarz results from personal samples ranged from below the limit of to

detection 01 1 inglm3 The TW A respirable quarz exposures for October 8 were 0013 mgm3 for the operator 0064 mgm3 for the foreman and 0030 mgm3 for the third

LOD formiling Crew member The TWAs were also calculated using the value of

001 mg Their 8-hour quartz TWAs were 0014 mgm3 0066 mglm3 and 0027 mgm3 respectively On October 8 the foremans TWA and 8-hour TWA exposure exceeded the NIOSH quarz REL of 005 nigm3

quarz results less than the LOD of

the milling crews respirable dust and respirable quartzTable 2 lists the results of

exposures by nozzle type and employee results in TWAs of21 mgm3 for the operator 062 mgm3 for the foreman and 11 mgm3 for the rear control operator for the UniJ etfI 11005 nozzle versus 14 mglm3 065 mgm3 and 089 mgm respectively forthe UniJetaeligl 11008 nozzle TWA

samples on October 9 Calculating TWA respirable dust

the operator 0041

mgm3 for the foreman and 0050 mgin3 for the worker operating the rear controls quartz results for the UniJetfI 11005 nozzle were 012 mgm3 for

8

0081 mgm3 for the operator TW A quarz results for the UniacuteJetlIII008 nozzle were

0041 mgm3 for the foreman and 0043 mgm3 for the thrd crewman In contrast to October 8 the operator received the highest exposures on the second sampling day

Table 3 shows that the highest emissionsthe nozzle type Inspection ofregardless of

side of the mil and the upper conveyor Unfortunately the weather station did not log data so the effect of the wind direction on those results is unnown

were associated with the left

the area samplescoUected on October 8 with the lower-flow respirable dust samplers (17 Lmin) and the pdR direct-reading instruments Those results indicate that for both sampling methods that exposures were lowest igraven the

Table 4 reports the results of

operators station and highest at the upper conveyor (the material transfer conveyor) This table also lists the gravimetricpDR ratios calculated for each sampling location These ratios were used to adjust pDR short teimsampling concentrations which are provided later in ths report Table 5 presents the results for the lower-flow respirable

dust samples and the pdR samples for October 9 including the results from all nozzle types The upper conveyor produced the highest exposure on that day as welL Perhaps the operators personal exposures differ from the area sample at his work station because

the time on one or the other side of the mm while the sampler was in the

he spends most of

his work station (Figure 7) Table 5 which provides the results ofthe center of

lower-flow andpdR area samples shows that as in Table 3 the highest emissions were associated with the left side of the mill and the upper conveyor The migraveU removed

the road so the left side oftlie mm was facing the pavedmaterial from the right side of

the road while the right side faced the previous cut This orientation may explain the milL The manufacturers

edge of

in par why the exposures were higher on the left side of

6 relates area samplingrepresentative attributed this result to passing truck trame Table

results to productivity water flow and water spray pressure while Table 7 describes the work done on October 9

When reviewing the results of sampling conducted on October 9 for the purpose of this study it is useful to compare the results obtained when the different water spray nozzles

logwere used For the purpose ofthisaualysis the results were converted to the natural

the data did not vary with(In) scale because on the log scale the varabmty of

concentration From the In scale analysis of the respirable dust results (Tables 8~ II) the ratio of the UniJ etlf 11005 nozzle to the DniJ et(szlig i 1008 nozzle results is the ratio of their geometric means 12 This indicates that the respirable dust measurements obtained

are about 20 higher thotigh the result is not statistically significant even at the lO signifcance leveL Results for the pDRs are while the UniJetlf 11005 nozzle was used

also about 20 higher for the UnijetQ 11005 and are also notsimilar Those results are

statistically significant at the 10 leveL Examination oftbe tables indicates that for mostthe

groupings the UniJetlIl1005 nozzle does give higher results Review of all of

the UniacuteJet(( 11005 nozzle resultsrespirable dust data from October 9 shows that 59 of

exceeded the PEL while 50 of the UniJetI 11008 nozzle results did so For personal breathing zone samples half of the results while the Unijet(szlig 11005 was in use exceeded

the UnijetlI 11008 results exceeded the PELthe PEL one third of

9

From the In scale analysis of the quarz samplig results (Tables 12-15) the ratio of the Uniet(szlig 11005 nozzle to the Uniet(szlig 11008 nozzle results is the ratio of their geometrc means 116 Thus for respirable quar the results while Uniet(szlig i 1005 nozzles were intalled on the cutter drm were about 16 higher though the result is not statisticaly signficant even at the 10 signcance leveL Examation of the tables indicates that the quar results are not as consistent as those for respirable dust For data from both days 7 respirable quar results were less than the LOD and 13 values were between LOD and LOQ For the seven quarz values below the LOD the value Lan was substituted

Quarz in bulk samples

The results of 10 bulk samples ranged from 12 to 28 with a mean of 199 and a median of 185

CONCLUSIONS AN RECOMMNDATIONS

Conclusions from ths pilot study regardig the effect of increasing the water flow to the spray nozzles on dust and quart exposures are lited by several factors First the higher flow nozzles were only intalled on the cutter dr and the cutter dr extension

the nozzles selected represent a difference of only 30 more flow when the higher-flow nozzles were installed Nevereless the respirable dust measurements obtaied while the Uniet(szlig 11005 nozzles were used were about 20 higher than when the higher-flow Uniet(szlig 11008 nozzles were used The respirable quarz results while Uniet(szlig 11005 nozzles were installed on the cutter dr were about 16 higher Neither

Second

the reductions in respirable dust concentrations nor those for the quarz results were statistically signficant even at the lO signficance leveL Statistical signficance mean that the difference is not due to chance alone

Research on dust controls in minig has shown that water sprays have two roles wetting of broken material being transported and airborne captue (NOSH 2003) Uniformly wetting the broken material durg the breakage process is far more effective and enures that dust paricles stay attached to the materal (NQSH 2003) Increasing the water flow rate and increasing the number of sprays have both been shown to be effective it is tooearly in this proj ect to recommend an approach In one inance dust from a shearer dr was reduced by 60 when the 46 smaler orifice nozzles were substituted for the originall7 nozzles with the pressure and flow held constant (NOSH 2003) The shape of the spray is another importnt factor in its effectveness

Futue studies might test the water system on a newer-model machie to begi to explore the relationship between water flow and pressue agravend aiborne dust concentrtions Varables related to the site andjob might obscure ths relationship but it is hoped that a trend might emerge

10

REFERENCES

29 CFR 19101000 (2001) Occupational Safety and Health Admstration air

containants

29 CFR 192655 (2003) Occupational Safety and Health Adminstration gases vapors fues dusts and mists

ACGrn (2004) Theshold limit values for chemical substances CincinatiOH American Conference of Governental Industral Hygienists

Akbar-Khanadeh F Brillhar RL (2002) Respirable crystallne silca dust exposure durng concrete finshing (grnding) using hand-held grnders in the constrction industr An occup Hyg 46341-346

Bureau of Mines (1992) Crystallne silica primer Washigton DC US Deparent of the Interior Bureau of Mines Branch of Industral Minerals Special Publication

Glindmeyer HW Hamad YY (1988) Contributing factors to sandblasters silcosis inadequate respiratory protection equipment and standards J accup Med 30917-921

HSE (1997) MDHS 142 General methods for sampling and gravimetrc analysis of respirable and total inhalable dust Methods for the determination of hazardous substances lIealth and safety laboratory Sudbur Suffolk UK Health and Safety Executive

Homuug R Reed L (1990) Estimation of average concentration in the presence of nondetectable values Applied Occupational and Environmental Hygiene 5(1)46-51

Linch KD (2002) Respirable concrete dust-silcosis hazard in the constrction industr

Appl Occup and Environ Hyg 17 209-221

Neuhauser Curt (curneuhauser(ecircdotstatewius) (2004) RE US 12 project Private e-mail message to Alan Echt (AEcht(ecirccdcgov) Januar 7

New Jersey Deparent of Health and Senior Services (2001) New Jersey silica parership In Occupational Health Sureilance Update February Trenton NJ NJ

Deparment of Health and Senior Services Division of Epidemiology Environmental and Occupational Health Occupational Health Service Occupational Health Sureilance Program

11

inch (psi) were used For the second and thd period higher-flow nozzles CUniJ etQI

model 11008 Spraying System Co Wheaton IL) rated at 08 gpm at 40 psi were installed on the cutter-dr spray bar Durng the final period the manufactuershy

specified nozzles were used again This design was used instead of a randomized design because of the length of time and effort required to change the nozzles in the field The spray nozzles for the primar conveyor and the material transfer conveyor were not changed Personal and high-flow area samples for respirable dust and respirable crystallne silica were changed approximately every two hours durig both sampling days The lower-flow area samples were collected for the full shift on both days

RESULTS AND DISCUSSION

Description of the Mil and the Controls

The miling machine used at this site had 3560 hours on the machine at the beginnng of the site visit It was equipped with water spray nozzles at three places including dr spraying nozzles primar conveyor spraying nozzles and material transfer conveying nozzles There were 18 flat fan spray nozzles (UniJetQI model 11005 SS Spraying Systems Co Wheaton IL) mounted on a spragravey bar in the cutter dru housing This type

of nozzle was used at all of the installations on this milL Thegrave fist thee nozzles on the cutter dr spray bar were mounted 2 inches (in) apar the thrd and fourh nozzle were

mounted 3 in apar and the remaining nozzles were 5 Yi in apar The cutter dr

extension was served by a separate spray bar equipped with thee nozzles The first two nozzles were 2in apar while the second and thrd nozzle were 5 Yi in apar There were a total of nine nozzles at the primary conveyor installed at the transition from the cutter dr to the primar conveyor four were mounted on each side and one on the extension

These nozzles were 1 foot apar There were two nozzles mounted above the material transfer conveyor at the transition from the primar cogravenveyor Those nozzles were 32 in apar New nozzles were installed on the evening before the first sampling day The water pump for the spraying system is rated at 40 Llmin (106 gallons) of water at 3 Yi bar (51 psi)

The 8 ft 6 in wide cutter dr held 193 bits aranged in a helical coil around the dr

holders were in factory spec condition with 50 hrs on the holders NewThe drm and

bits were installed on the evening before the first sampling day and were changed several times durg the next two days The dr rotation was measured and found to agree with

the manufacturers specification of928 rpm

Personal protective equipment and work practices

The miling crew members wore hard hats (except the operator) safety glasses and traffc safety vests The operator was the only employee who spent all of his time on the mil operating the mil from either the right or left side of the operators station The foreman spent the majority of the first day operatig the rear controls while the thid ecircrewman performed tasks such as operating a skid-steer loader and drvig the water

7

in the afternoon the foreman operated the skid steer loader while the third crewman ran the rear controls For the most par the skid-steer loader was not operated near the miling machine on the first day On one occasion a road grader passed by and for a brief period in the afternoon nugravellig took place alongside a field while a farer was running a combine On the second day the skid-steer loader

truck (Figure 6) However

the daythe day and the third crew member spent most ofwas idle for the majority of

the rear controls The foreman left the migravelperiodically to attend torunning one of

matters such as trck scheduling On both days the trcks assigned to take away thepossiblethe road unti that was no longermiled material drove on the paved portion of

lessening the potential of dust being generated by the trucks as they passed the millng machine

Respirable dust and crystallne silica sampling results

personal breathing zone sampling for respirable dust and crystalline silica conducted on October 8 are presented in Table 1 On October 8 which represented a typical millng day respirable dust results ranged from 014 to 183 mgm The TW A respirable dust exposures for the three employees were 026 mgmJ (499 minutes) for the

The results of

operator 10 mgm3 (495 minutes) for the foreman and 038 mgm3 (438 minutes) for the third employee who began the day operatin~ the skid steer loader Their 8-hour TWAs were 027 mgm3 for the operator 10 mgm for the foreman and 035 mgm3 for the third crew member The OSHA PELs for these employees calculated based upon the percent silica in their samples were 142 mgm 3 for the operator 117 mgm3 for the foreman and 113 mgm3 for the third member of the miling crew The PELs were calculated using the value of the LODJ for quarz values below the LOD (Hornung and Reed 1990) None of the employees exposures exceeded the OSHA PEL on October 8 as a TW A but excursions above the PEL did take place during the first two sampling periods for the foreman who spent most of those periods operating the rear controls on the mUL

Respirable quarz results from personal samples ranged from below the limit of to

detection 01 1 inglm3 The TW A respirable quarz exposures for October 8 were 0013 mgm3 for the operator 0064 mgm3 for the foreman and 0030 mgm3 for the third

LOD formiling Crew member The TWAs were also calculated using the value of

001 mg Their 8-hour quartz TWAs were 0014 mgm3 0066 mglm3 and 0027 mgm3 respectively On October 8 the foremans TWA and 8-hour TWA exposure exceeded the NIOSH quarz REL of 005 nigm3

quarz results less than the LOD of

the milling crews respirable dust and respirable quartzTable 2 lists the results of

exposures by nozzle type and employee results in TWAs of21 mgm3 for the operator 062 mgm3 for the foreman and 11 mgm3 for the rear control operator for the UniJ etfI 11005 nozzle versus 14 mglm3 065 mgm3 and 089 mgm respectively forthe UniJetaeligl 11008 nozzle TWA

samples on October 9 Calculating TWA respirable dust

the operator 0041

mgm3 for the foreman and 0050 mgin3 for the worker operating the rear controls quartz results for the UniJetfI 11005 nozzle were 012 mgm3 for

8

0081 mgm3 for the operator TW A quarz results for the UniacuteJetlIII008 nozzle were

0041 mgm3 for the foreman and 0043 mgm3 for the thrd crewman In contrast to October 8 the operator received the highest exposures on the second sampling day

Table 3 shows that the highest emissionsthe nozzle type Inspection ofregardless of

side of the mil and the upper conveyor Unfortunately the weather station did not log data so the effect of the wind direction on those results is unnown

were associated with the left

the area samplescoUected on October 8 with the lower-flow respirable dust samplers (17 Lmin) and the pdR direct-reading instruments Those results indicate that for both sampling methods that exposures were lowest igraven the

Table 4 reports the results of

operators station and highest at the upper conveyor (the material transfer conveyor) This table also lists the gravimetricpDR ratios calculated for each sampling location These ratios were used to adjust pDR short teimsampling concentrations which are provided later in ths report Table 5 presents the results for the lower-flow respirable

dust samples and the pdR samples for October 9 including the results from all nozzle types The upper conveyor produced the highest exposure on that day as welL Perhaps the operators personal exposures differ from the area sample at his work station because

the time on one or the other side of the mm while the sampler was in the

he spends most of

his work station (Figure 7) Table 5 which provides the results ofthe center of

lower-flow andpdR area samples shows that as in Table 3 the highest emissions were associated with the left side of the mill and the upper conveyor The migraveU removed

the road so the left side oftlie mm was facing the pavedmaterial from the right side of

the road while the right side faced the previous cut This orientation may explain the milL The manufacturers

edge of

in par why the exposures were higher on the left side of

6 relates area samplingrepresentative attributed this result to passing truck trame Table

results to productivity water flow and water spray pressure while Table 7 describes the work done on October 9

When reviewing the results of sampling conducted on October 9 for the purpose of this study it is useful to compare the results obtained when the different water spray nozzles

logwere used For the purpose ofthisaualysis the results were converted to the natural

the data did not vary with(In) scale because on the log scale the varabmty of

concentration From the In scale analysis of the respirable dust results (Tables 8~ II) the ratio of the UniJ etlf 11005 nozzle to the DniJ et(szlig i 1008 nozzle results is the ratio of their geometric means 12 This indicates that the respirable dust measurements obtained

are about 20 higher thotigh the result is not statistically significant even at the lO signifcance leveL Results for the pDRs are while the UniJetlf 11005 nozzle was used

also about 20 higher for the UnijetQ 11005 and are also notsimilar Those results are

statistically significant at the 10 leveL Examination oftbe tables indicates that for mostthe

groupings the UniJetlIl1005 nozzle does give higher results Review of all of

the UniacuteJet(( 11005 nozzle resultsrespirable dust data from October 9 shows that 59 of

exceeded the PEL while 50 of the UniJetI 11008 nozzle results did so For personal breathing zone samples half of the results while the Unijet(szlig 11005 was in use exceeded

the UnijetlI 11008 results exceeded the PELthe PEL one third of

9

From the In scale analysis of the quarz samplig results (Tables 12-15) the ratio of the Uniet(szlig 11005 nozzle to the Uniet(szlig 11008 nozzle results is the ratio of their geometrc means 116 Thus for respirable quar the results while Uniet(szlig i 1005 nozzles were intalled on the cutter drm were about 16 higher though the result is not statisticaly signficant even at the 10 signcance leveL Examation of the tables indicates that the quar results are not as consistent as those for respirable dust For data from both days 7 respirable quar results were less than the LOD and 13 values were between LOD and LOQ For the seven quarz values below the LOD the value Lan was substituted

Quarz in bulk samples

The results of 10 bulk samples ranged from 12 to 28 with a mean of 199 and a median of 185

CONCLUSIONS AN RECOMMNDATIONS

Conclusions from ths pilot study regardig the effect of increasing the water flow to the spray nozzles on dust and quart exposures are lited by several factors First the higher flow nozzles were only intalled on the cutter dr and the cutter dr extension

the nozzles selected represent a difference of only 30 more flow when the higher-flow nozzles were installed Nevereless the respirable dust measurements obtaied while the Uniet(szlig 11005 nozzles were used were about 20 higher than when the higher-flow Uniet(szlig 11008 nozzles were used The respirable quarz results while Uniet(szlig 11005 nozzles were installed on the cutter dr were about 16 higher Neither

Second

the reductions in respirable dust concentrations nor those for the quarz results were statistically signficant even at the lO signficance leveL Statistical signficance mean that the difference is not due to chance alone

Research on dust controls in minig has shown that water sprays have two roles wetting of broken material being transported and airborne captue (NOSH 2003) Uniformly wetting the broken material durg the breakage process is far more effective and enures that dust paricles stay attached to the materal (NQSH 2003) Increasing the water flow rate and increasing the number of sprays have both been shown to be effective it is tooearly in this proj ect to recommend an approach In one inance dust from a shearer dr was reduced by 60 when the 46 smaler orifice nozzles were substituted for the originall7 nozzles with the pressure and flow held constant (NOSH 2003) The shape of the spray is another importnt factor in its effectveness

Futue studies might test the water system on a newer-model machie to begi to explore the relationship between water flow and pressue agravend aiborne dust concentrtions Varables related to the site andjob might obscure ths relationship but it is hoped that a trend might emerge

10

REFERENCES

29 CFR 19101000 (2001) Occupational Safety and Health Admstration air

containants

29 CFR 192655 (2003) Occupational Safety and Health Adminstration gases vapors fues dusts and mists

ACGrn (2004) Theshold limit values for chemical substances CincinatiOH American Conference of Governental Industral Hygienists

Akbar-Khanadeh F Brillhar RL (2002) Respirable crystallne silca dust exposure durng concrete finshing (grnding) using hand-held grnders in the constrction industr An occup Hyg 46341-346

Bureau of Mines (1992) Crystallne silica primer Washigton DC US Deparent of the Interior Bureau of Mines Branch of Industral Minerals Special Publication

Glindmeyer HW Hamad YY (1988) Contributing factors to sandblasters silcosis inadequate respiratory protection equipment and standards J accup Med 30917-921

HSE (1997) MDHS 142 General methods for sampling and gravimetrc analysis of respirable and total inhalable dust Methods for the determination of hazardous substances lIealth and safety laboratory Sudbur Suffolk UK Health and Safety Executive

Homuug R Reed L (1990) Estimation of average concentration in the presence of nondetectable values Applied Occupational and Environmental Hygiene 5(1)46-51

Linch KD (2002) Respirable concrete dust-silcosis hazard in the constrction industr

Appl Occup and Environ Hyg 17 209-221

Neuhauser Curt (curneuhauser(ecircdotstatewius) (2004) RE US 12 project Private e-mail message to Alan Echt (AEcht(ecirccdcgov) Januar 7

New Jersey Deparent of Health and Senior Services (2001) New Jersey silica parership In Occupational Health Sureilance Update February Trenton NJ NJ

Deparment of Health and Senior Services Division of Epidemiology Environmental and Occupational Health Occupational Health Service Occupational Health Sureilance Program

11

in the afternoon the foreman operated the skid steer loader while the third crewman ran the rear controls For the most par the skid-steer loader was not operated near the miling machine on the first day On one occasion a road grader passed by and for a brief period in the afternoon nugravellig took place alongside a field while a farer was running a combine On the second day the skid-steer loader

truck (Figure 6) However

the daythe day and the third crew member spent most ofwas idle for the majority of

the rear controls The foreman left the migravelperiodically to attend torunning one of

matters such as trck scheduling On both days the trcks assigned to take away thepossiblethe road unti that was no longermiled material drove on the paved portion of

lessening the potential of dust being generated by the trucks as they passed the millng machine

Respirable dust and crystallne silica sampling results

personal breathing zone sampling for respirable dust and crystalline silica conducted on October 8 are presented in Table 1 On October 8 which represented a typical millng day respirable dust results ranged from 014 to 183 mgm The TW A respirable dust exposures for the three employees were 026 mgmJ (499 minutes) for the

The results of

operator 10 mgm3 (495 minutes) for the foreman and 038 mgm3 (438 minutes) for the third employee who began the day operatin~ the skid steer loader Their 8-hour TWAs were 027 mgm3 for the operator 10 mgm for the foreman and 035 mgm3 for the third crew member The OSHA PELs for these employees calculated based upon the percent silica in their samples were 142 mgm 3 for the operator 117 mgm3 for the foreman and 113 mgm3 for the third member of the miling crew The PELs were calculated using the value of the LODJ for quarz values below the LOD (Hornung and Reed 1990) None of the employees exposures exceeded the OSHA PEL on October 8 as a TW A but excursions above the PEL did take place during the first two sampling periods for the foreman who spent most of those periods operating the rear controls on the mUL

Respirable quarz results from personal samples ranged from below the limit of to

detection 01 1 inglm3 The TW A respirable quarz exposures for October 8 were 0013 mgm3 for the operator 0064 mgm3 for the foreman and 0030 mgm3 for the third

LOD formiling Crew member The TWAs were also calculated using the value of

001 mg Their 8-hour quartz TWAs were 0014 mgm3 0066 mglm3 and 0027 mgm3 respectively On October 8 the foremans TWA and 8-hour TWA exposure exceeded the NIOSH quarz REL of 005 nigm3

quarz results less than the LOD of

the milling crews respirable dust and respirable quartzTable 2 lists the results of

exposures by nozzle type and employee results in TWAs of21 mgm3 for the operator 062 mgm3 for the foreman and 11 mgm3 for the rear control operator for the UniJ etfI 11005 nozzle versus 14 mglm3 065 mgm3 and 089 mgm respectively forthe UniJetaeligl 11008 nozzle TWA

samples on October 9 Calculating TWA respirable dust

the operator 0041

mgm3 for the foreman and 0050 mgin3 for the worker operating the rear controls quartz results for the UniJetfI 11005 nozzle were 012 mgm3 for

8

0081 mgm3 for the operator TW A quarz results for the UniacuteJetlIII008 nozzle were

0041 mgm3 for the foreman and 0043 mgm3 for the thrd crewman In contrast to October 8 the operator received the highest exposures on the second sampling day

Table 3 shows that the highest emissionsthe nozzle type Inspection ofregardless of

side of the mil and the upper conveyor Unfortunately the weather station did not log data so the effect of the wind direction on those results is unnown

were associated with the left

the area samplescoUected on October 8 with the lower-flow respirable dust samplers (17 Lmin) and the pdR direct-reading instruments Those results indicate that for both sampling methods that exposures were lowest igraven the

Table 4 reports the results of

operators station and highest at the upper conveyor (the material transfer conveyor) This table also lists the gravimetricpDR ratios calculated for each sampling location These ratios were used to adjust pDR short teimsampling concentrations which are provided later in ths report Table 5 presents the results for the lower-flow respirable

dust samples and the pdR samples for October 9 including the results from all nozzle types The upper conveyor produced the highest exposure on that day as welL Perhaps the operators personal exposures differ from the area sample at his work station because

the time on one or the other side of the mm while the sampler was in the

he spends most of

his work station (Figure 7) Table 5 which provides the results ofthe center of

lower-flow andpdR area samples shows that as in Table 3 the highest emissions were associated with the left side of the mill and the upper conveyor The migraveU removed

the road so the left side oftlie mm was facing the pavedmaterial from the right side of

the road while the right side faced the previous cut This orientation may explain the milL The manufacturers

edge of

in par why the exposures were higher on the left side of

6 relates area samplingrepresentative attributed this result to passing truck trame Table

results to productivity water flow and water spray pressure while Table 7 describes the work done on October 9

When reviewing the results of sampling conducted on October 9 for the purpose of this study it is useful to compare the results obtained when the different water spray nozzles

logwere used For the purpose ofthisaualysis the results were converted to the natural

the data did not vary with(In) scale because on the log scale the varabmty of

concentration From the In scale analysis of the respirable dust results (Tables 8~ II) the ratio of the UniJ etlf 11005 nozzle to the DniJ et(szlig i 1008 nozzle results is the ratio of their geometric means 12 This indicates that the respirable dust measurements obtained

are about 20 higher thotigh the result is not statistically significant even at the lO signifcance leveL Results for the pDRs are while the UniJetlf 11005 nozzle was used

also about 20 higher for the UnijetQ 11005 and are also notsimilar Those results are

statistically significant at the 10 leveL Examination oftbe tables indicates that for mostthe

groupings the UniJetlIl1005 nozzle does give higher results Review of all of

the UniacuteJet(( 11005 nozzle resultsrespirable dust data from October 9 shows that 59 of

exceeded the PEL while 50 of the UniJetI 11008 nozzle results did so For personal breathing zone samples half of the results while the Unijet(szlig 11005 was in use exceeded

the UnijetlI 11008 results exceeded the PELthe PEL one third of

9

From the In scale analysis of the quarz samplig results (Tables 12-15) the ratio of the Uniet(szlig 11005 nozzle to the Uniet(szlig 11008 nozzle results is the ratio of their geometrc means 116 Thus for respirable quar the results while Uniet(szlig i 1005 nozzles were intalled on the cutter drm were about 16 higher though the result is not statisticaly signficant even at the 10 signcance leveL Examation of the tables indicates that the quar results are not as consistent as those for respirable dust For data from both days 7 respirable quar results were less than the LOD and 13 values were between LOD and LOQ For the seven quarz values below the LOD the value Lan was substituted

Quarz in bulk samples

The results of 10 bulk samples ranged from 12 to 28 with a mean of 199 and a median of 185

CONCLUSIONS AN RECOMMNDATIONS

Conclusions from ths pilot study regardig the effect of increasing the water flow to the spray nozzles on dust and quart exposures are lited by several factors First the higher flow nozzles were only intalled on the cutter dr and the cutter dr extension

the nozzles selected represent a difference of only 30 more flow when the higher-flow nozzles were installed Nevereless the respirable dust measurements obtaied while the Uniet(szlig 11005 nozzles were used were about 20 higher than when the higher-flow Uniet(szlig 11008 nozzles were used The respirable quarz results while Uniet(szlig 11005 nozzles were installed on the cutter dr were about 16 higher Neither

Second

the reductions in respirable dust concentrations nor those for the quarz results were statistically signficant even at the lO signficance leveL Statistical signficance mean that the difference is not due to chance alone

Research on dust controls in minig has shown that water sprays have two roles wetting of broken material being transported and airborne captue (NOSH 2003) Uniformly wetting the broken material durg the breakage process is far more effective and enures that dust paricles stay attached to the materal (NQSH 2003) Increasing the water flow rate and increasing the number of sprays have both been shown to be effective it is tooearly in this proj ect to recommend an approach In one inance dust from a shearer dr was reduced by 60 when the 46 smaler orifice nozzles were substituted for the originall7 nozzles with the pressure and flow held constant (NOSH 2003) The shape of the spray is another importnt factor in its effectveness

Futue studies might test the water system on a newer-model machie to begi to explore the relationship between water flow and pressue agravend aiborne dust concentrtions Varables related to the site andjob might obscure ths relationship but it is hoped that a trend might emerge

10

REFERENCES

29 CFR 19101000 (2001) Occupational Safety and Health Admstration air

containants

29 CFR 192655 (2003) Occupational Safety and Health Adminstration gases vapors fues dusts and mists

ACGrn (2004) Theshold limit values for chemical substances CincinatiOH American Conference of Governental Industral Hygienists

Akbar-Khanadeh F Brillhar RL (2002) Respirable crystallne silca dust exposure durng concrete finshing (grnding) using hand-held grnders in the constrction industr An occup Hyg 46341-346

Bureau of Mines (1992) Crystallne silica primer Washigton DC US Deparent of the Interior Bureau of Mines Branch of Industral Minerals Special Publication

Glindmeyer HW Hamad YY (1988) Contributing factors to sandblasters silcosis inadequate respiratory protection equipment and standards J accup Med 30917-921

HSE (1997) MDHS 142 General methods for sampling and gravimetrc analysis of respirable and total inhalable dust Methods for the determination of hazardous substances lIealth and safety laboratory Sudbur Suffolk UK Health and Safety Executive

Homuug R Reed L (1990) Estimation of average concentration in the presence of nondetectable values Applied Occupational and Environmental Hygiene 5(1)46-51

Linch KD (2002) Respirable concrete dust-silcosis hazard in the constrction industr

Appl Occup and Environ Hyg 17 209-221

Neuhauser Curt (curneuhauser(ecircdotstatewius) (2004) RE US 12 project Private e-mail message to Alan Echt (AEcht(ecirccdcgov) Januar 7

New Jersey Deparent of Health and Senior Services (2001) New Jersey silica parership In Occupational Health Sureilance Update February Trenton NJ NJ

Deparment of Health and Senior Services Division of Epidemiology Environmental and Occupational Health Occupational Health Service Occupational Health Sureilance Program

11

0081 mgm3 for the operator TW A quarz results for the UniacuteJetlIII008 nozzle were

0041 mgm3 for the foreman and 0043 mgm3 for the thrd crewman In contrast to October 8 the operator received the highest exposures on the second sampling day

Table 3 shows that the highest emissionsthe nozzle type Inspection ofregardless of

side of the mil and the upper conveyor Unfortunately the weather station did not log data so the effect of the wind direction on those results is unnown

were associated with the left

the area samplescoUected on October 8 with the lower-flow respirable dust samplers (17 Lmin) and the pdR direct-reading instruments Those results indicate that for both sampling methods that exposures were lowest igraven the

Table 4 reports the results of

operators station and highest at the upper conveyor (the material transfer conveyor) This table also lists the gravimetricpDR ratios calculated for each sampling location These ratios were used to adjust pDR short teimsampling concentrations which are provided later in ths report Table 5 presents the results for the lower-flow respirable

dust samples and the pdR samples for October 9 including the results from all nozzle types The upper conveyor produced the highest exposure on that day as welL Perhaps the operators personal exposures differ from the area sample at his work station because

the time on one or the other side of the mm while the sampler was in the

he spends most of

his work station (Figure 7) Table 5 which provides the results ofthe center of

lower-flow andpdR area samples shows that as in Table 3 the highest emissions were associated with the left side of the mill and the upper conveyor The migraveU removed

the road so the left side oftlie mm was facing the pavedmaterial from the right side of

the road while the right side faced the previous cut This orientation may explain the milL The manufacturers

edge of

in par why the exposures were higher on the left side of

6 relates area samplingrepresentative attributed this result to passing truck trame Table

results to productivity water flow and water spray pressure while Table 7 describes the work done on October 9

When reviewing the results of sampling conducted on October 9 for the purpose of this study it is useful to compare the results obtained when the different water spray nozzles

logwere used For the purpose ofthisaualysis the results were converted to the natural

the data did not vary with(In) scale because on the log scale the varabmty of

concentration From the In scale analysis of the respirable dust results (Tables 8~ II) the ratio of the UniJ etlf 11005 nozzle to the DniJ et(szlig i 1008 nozzle results is the ratio of their geometric means 12 This indicates that the respirable dust measurements obtained

are about 20 higher thotigh the result is not statistically significant even at the lO signifcance leveL Results for the pDRs are while the UniJetlf 11005 nozzle was used

also about 20 higher for the UnijetQ 11005 and are also notsimilar Those results are

statistically significant at the 10 leveL Examination oftbe tables indicates that for mostthe

groupings the UniJetlIl1005 nozzle does give higher results Review of all of

the UniacuteJet(( 11005 nozzle resultsrespirable dust data from October 9 shows that 59 of

exceeded the PEL while 50 of the UniJetI 11008 nozzle results did so For personal breathing zone samples half of the results while the Unijet(szlig 11005 was in use exceeded

the UnijetlI 11008 results exceeded the PELthe PEL one third of

9

From the In scale analysis of the quarz samplig results (Tables 12-15) the ratio of the Uniet(szlig 11005 nozzle to the Uniet(szlig 11008 nozzle results is the ratio of their geometrc means 116 Thus for respirable quar the results while Uniet(szlig i 1005 nozzles were intalled on the cutter drm were about 16 higher though the result is not statisticaly signficant even at the 10 signcance leveL Examation of the tables indicates that the quar results are not as consistent as those for respirable dust For data from both days 7 respirable quar results were less than the LOD and 13 values were between LOD and LOQ For the seven quarz values below the LOD the value Lan was substituted

Quarz in bulk samples

The results of 10 bulk samples ranged from 12 to 28 with a mean of 199 and a median of 185

CONCLUSIONS AN RECOMMNDATIONS

Conclusions from ths pilot study regardig the effect of increasing the water flow to the spray nozzles on dust and quart exposures are lited by several factors First the higher flow nozzles were only intalled on the cutter dr and the cutter dr extension

the nozzles selected represent a difference of only 30 more flow when the higher-flow nozzles were installed Nevereless the respirable dust measurements obtaied while the Uniet(szlig 11005 nozzles were used were about 20 higher than when the higher-flow Uniet(szlig 11008 nozzles were used The respirable quarz results while Uniet(szlig 11005 nozzles were installed on the cutter dr were about 16 higher Neither

Second

the reductions in respirable dust concentrations nor those for the quarz results were statistically signficant even at the lO signficance leveL Statistical signficance mean that the difference is not due to chance alone

Research on dust controls in minig has shown that water sprays have two roles wetting of broken material being transported and airborne captue (NOSH 2003) Uniformly wetting the broken material durg the breakage process is far more effective and enures that dust paricles stay attached to the materal (NQSH 2003) Increasing the water flow rate and increasing the number of sprays have both been shown to be effective it is tooearly in this proj ect to recommend an approach In one inance dust from a shearer dr was reduced by 60 when the 46 smaler orifice nozzles were substituted for the originall7 nozzles with the pressure and flow held constant (NOSH 2003) The shape of the spray is another importnt factor in its effectveness

Futue studies might test the water system on a newer-model machie to begi to explore the relationship between water flow and pressue agravend aiborne dust concentrtions Varables related to the site andjob might obscure ths relationship but it is hoped that a trend might emerge

10

REFERENCES

29 CFR 19101000 (2001) Occupational Safety and Health Admstration air

containants

29 CFR 192655 (2003) Occupational Safety and Health Adminstration gases vapors fues dusts and mists

ACGrn (2004) Theshold limit values for chemical substances CincinatiOH American Conference of Governental Industral Hygienists

Akbar-Khanadeh F Brillhar RL (2002) Respirable crystallne silca dust exposure durng concrete finshing (grnding) using hand-held grnders in the constrction industr An occup Hyg 46341-346

Bureau of Mines (1992) Crystallne silica primer Washigton DC US Deparent of the Interior Bureau of Mines Branch of Industral Minerals Special Publication

Glindmeyer HW Hamad YY (1988) Contributing factors to sandblasters silcosis inadequate respiratory protection equipment and standards J accup Med 30917-921

HSE (1997) MDHS 142 General methods for sampling and gravimetrc analysis of respirable and total inhalable dust Methods for the determination of hazardous substances lIealth and safety laboratory Sudbur Suffolk UK Health and Safety Executive

Homuug R Reed L (1990) Estimation of average concentration in the presence of nondetectable values Applied Occupational and Environmental Hygiene 5(1)46-51

Linch KD (2002) Respirable concrete dust-silcosis hazard in the constrction industr

Appl Occup and Environ Hyg 17 209-221

Neuhauser Curt (curneuhauser(ecircdotstatewius) (2004) RE US 12 project Private e-mail message to Alan Echt (AEcht(ecirccdcgov) Januar 7

New Jersey Deparent of Health and Senior Services (2001) New Jersey silica parership In Occupational Health Sureilance Update February Trenton NJ NJ

Deparment of Health and Senior Services Division of Epidemiology Environmental and Occupational Health Occupational Health Service Occupational Health Sureilance Program

11

From the In scale analysis of the quarz samplig results (Tables 12-15) the ratio of the Uniet(szlig 11005 nozzle to the Uniet(szlig 11008 nozzle results is the ratio of their geometrc means 116 Thus for respirable quar the results while Uniet(szlig i 1005 nozzles were intalled on the cutter drm were about 16 higher though the result is not statisticaly signficant even at the 10 signcance leveL Examation of the tables indicates that the quar results are not as consistent as those for respirable dust For data from both days 7 respirable quar results were less than the LOD and 13 values were between LOD and LOQ For the seven quarz values below the LOD the value Lan was substituted

Quarz in bulk samples

The results of 10 bulk samples ranged from 12 to 28 with a mean of 199 and a median of 185

CONCLUSIONS AN RECOMMNDATIONS

Conclusions from ths pilot study regardig the effect of increasing the water flow to the spray nozzles on dust and quart exposures are lited by several factors First the higher flow nozzles were only intalled on the cutter dr and the cutter dr extension

the nozzles selected represent a difference of only 30 more flow when the higher-flow nozzles were installed Nevereless the respirable dust measurements obtaied while the Uniet(szlig 11005 nozzles were used were about 20 higher than when the higher-flow Uniet(szlig 11008 nozzles were used The respirable quarz results while Uniet(szlig 11005 nozzles were installed on the cutter dr were about 16 higher Neither

Second

the reductions in respirable dust concentrations nor those for the quarz results were statistically signficant even at the lO signficance leveL Statistical signficance mean that the difference is not due to chance alone

Research on dust controls in minig has shown that water sprays have two roles wetting of broken material being transported and airborne captue (NOSH 2003) Uniformly wetting the broken material durg the breakage process is far more effective and enures that dust paricles stay attached to the materal (NQSH 2003) Increasing the water flow rate and increasing the number of sprays have both been shown to be effective it is tooearly in this proj ect to recommend an approach In one inance dust from a shearer dr was reduced by 60 when the 46 smaler orifice nozzles were substituted for the originall7 nozzles with the pressure and flow held constant (NOSH 2003) The shape of the spray is another importnt factor in its effectveness

Futue studies might test the water system on a newer-model machie to begi to explore the relationship between water flow and pressue agravend aiborne dust concentrtions Varables related to the site andjob might obscure ths relationship but it is hoped that a trend might emerge

10

REFERENCES

29 CFR 19101000 (2001) Occupational Safety and Health Admstration air

containants

29 CFR 192655 (2003) Occupational Safety and Health Adminstration gases vapors fues dusts and mists

ACGrn (2004) Theshold limit values for chemical substances CincinatiOH American Conference of Governental Industral Hygienists

Akbar-Khanadeh F Brillhar RL (2002) Respirable crystallne silca dust exposure durng concrete finshing (grnding) using hand-held grnders in the constrction industr An occup Hyg 46341-346

Bureau of Mines (1992) Crystallne silica primer Washigton DC US Deparent of the Interior Bureau of Mines Branch of Industral Minerals Special Publication

Glindmeyer HW Hamad YY (1988) Contributing factors to sandblasters silcosis inadequate respiratory protection equipment and standards J accup Med 30917-921

HSE (1997) MDHS 142 General methods for sampling and gravimetrc analysis of respirable and total inhalable dust Methods for the determination of hazardous substances lIealth and safety laboratory Sudbur Suffolk UK Health and Safety Executive

Homuug R Reed L (1990) Estimation of average concentration in the presence of nondetectable values Applied Occupational and Environmental Hygiene 5(1)46-51

Linch KD (2002) Respirable concrete dust-silcosis hazard in the constrction industr

Appl Occup and Environ Hyg 17 209-221

Neuhauser Curt (curneuhauser(ecircdotstatewius) (2004) RE US 12 project Private e-mail message to Alan Echt (AEcht(ecirccdcgov) Januar 7

New Jersey Deparent of Health and Senior Services (2001) New Jersey silica parership In Occupational Health Sureilance Update February Trenton NJ NJ

Deparment of Health and Senior Services Division of Epidemiology Environmental and Occupational Health Occupational Health Service Occupational Health Sureilance Program

11

REFERENCES

29 CFR 19101000 (2001) Occupational Safety and Health Admstration air

containants

29 CFR 192655 (2003) Occupational Safety and Health Adminstration gases vapors fues dusts and mists

ACGrn (2004) Theshold limit values for chemical substances CincinatiOH American Conference of Governental Industral Hygienists

Akbar-Khanadeh F Brillhar RL (2002) Respirable crystallne silca dust exposure durng concrete finshing (grnding) using hand-held grnders in the constrction industr An occup Hyg 46341-346

Bureau of Mines (1992) Crystallne silica primer Washigton DC US Deparent of the Interior Bureau of Mines Branch of Industral Minerals Special Publication

Glindmeyer HW Hamad YY (1988) Contributing factors to sandblasters silcosis inadequate respiratory protection equipment and standards J accup Med 30917-921

HSE (1997) MDHS 142 General methods for sampling and gravimetrc analysis of respirable and total inhalable dust Methods for the determination of hazardous substances lIealth and safety laboratory Sudbur Suffolk UK Health and Safety Executive

Homuug R Reed L (1990) Estimation of average concentration in the presence of nondetectable values Applied Occupational and Environmental Hygiene 5(1)46-51

Linch KD (2002) Respirable concrete dust-silcosis hazard in the constrction industr

Appl Occup and Environ Hyg 17 209-221

Neuhauser Curt (curneuhauser(ecircdotstatewius) (2004) RE US 12 project Private e-mail message to Alan Echt (AEcht(ecirccdcgov) Januar 7

New Jersey Deparent of Health and Senior Services (2001) New Jersey silica parership In Occupational Health Sureilance Update February Trenton NJ NJ

Deparment of Health and Senior Services Division of Epidemiology Environmental and Occupational Health Occupational Health Service Occupational Health Sureilance Program

11

NlOSH (1994) NIOSH manual of analytical methods 4th rev ed Eller PM edHealth and Human Services Public Health Service

Cincinnati OH Us Deparment of

Centers for Disease Control and Prevention National Institute for Occupational Safety and Health DHHS (NIOSH) Publication No 94-113

NJOSH (2000) Respirable crystallie silica exposures during tuck pointing Cincinnati OH US Deparent of Health and Human Servces Public Health Service Centers for Disease Control and Prevention National Institute for Occupational Safety and Health DHHS (NIOSH) Publication No 2000-113

NIOSH (2002) NIOSH hazard review health effects of occupational exposure toHealth and Human

respirable crystallne silca Cincinnati OH US Department of

Institute for OccupationalServices Centers for Disease Control and Prevention National

Safety and Health DHHS (NIOSH) Publication No 2002-129

NIOSH (2003) Inormation Circular2003 Handbook for dust control in mining Health and Human Services Public Health Service

Centers for Disease Control and Prevention Naringtional Institute for Occupational Safety and Health Pittsburgh Research Laboratory IC 9465 DHHS (NIOSH) Publication No 2003-147

Pittsburgh P A US Deparment of

OSHA (1996) Memorandum for regional administrators from Joseph A Dear Subject special emphasis program (SEP) for silcosis May 2nd 1996 Appendix F Pemiissible Exposure Limits for Constrction and Maritime Retreved May 24 2004 from httpww osha gov SiacutelcaSpecialEmphasishtml

15 1995Publigravec Works (1995) Pavement recycling Public Works 126 April

Rappaport 8M Goldberg M Susi p Herrick RF (2003) Excessive exposure to silica in the US construction industr An occup Hyg 47111-122

the effectiveness Thorpe A Ritchie AS Gibson MJ Brown RC (1999) Measurements of

of dust control on cut-off saws used in the construction industry Ann occup Hyg 43443-456

12

Personal Breathing Zone Samples Payne and Dolan October 8 2003

Respirable Respirable Respirable OSHA Respirable

Table 1 Results of

Time Percent Volume Job Dust Quarz Dust PEL Quartz

(min) Quarz (L)(mg) (mg) (mgm3) (mgm3) (mgm3)

Operator 146 019 (001) (526) 598 032 138 (002) 069 005 754 549 126 105 009Foreman 142

137 037 003 892 569 065 092 006Skid steer 639 014 500Operator 156 0087 NO 600 183 124 011Foreman 155 11 007 609 636 035 153 (002)Skid steer 153 022 (001) (455)

Operator 197 026 (001) (385) 807 032 171 (001) 766 020 500Foreman 198 015 ND

016 500Skid steer 148 0098 ND 615

Notes All results are field-blan corrected NO indicates a result less than the limit of detection for this method of 1 Oiexclg of quarz per sample Results in parentheses indicate a semi-quantitative value between the limit of detection and the limit of quantitation

13

Table 2 Results of Personal Breathg Zone Samples Payne and Dolan October 92003

Respirable Respirable Respirable OSHA RespirableTime Percent VolumeJob Dust Quarz Dust PEL Quarz(min) Quarz (L)(mg) (mg) (mgm3) (mgm3) (mgm3) UniJetQ 11005 Nozzle

Operator 138 13 008 600 572 227 125 014 Foreman 117 04 (003) (750) 499 080 105 (006) Rear Control 105 023 (001) (435) 435 053 158 (002)

~ UnigraveJet91lO08Nozzle ~ Ooerator HI 069 003 493 460

l50 144 001

Foreman 114 022 (001 ) (455) 486

045 153 XOOL) Rear Control 111 059 (003) (508) 460 128 14L fO07)

d Dniecirct~ 11008 Nozzle f

Operator 132 069 005 681 547 L26 113 009 Forerraringn 125 Q44 003 750 533

OS3 105 006 ~

Rear Control 134 031 (001) (323) 556 OS6 Ln (002) UniJet 11005 Nozzle

Operator 114 093 005 495 472 197 144 010 Foreman 111 021 (001) (476) 473 044 148 (002) Rear Control 107 072 003 472 444 162 149 008

Notes All results are field-blan corrected

ND indicates a result less than the limit of detection for this method of 10 lJg of quarz per sample Results in parentheses indicate a semi-quantitative value between the limit of detection and the limit of quantitation

14

Tab

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sample Results in parntheses indicate a semi-quatitative value between the lit of detection and the lit of quantitation

Table 4 Low-Flow and pDR Area Sample Results Payne and Dolan October 8 2003

Sampling Location

Sample Time (min)

Gravimetrc Respirable Dust

(mglm3)

Average Respirable

Dust at Location (mgm3)

pDR Respirable Dust

(mglm3)

GravimetrcpDR Ratio

498 0309

Operator 032 0216 1469

501 0325

514 0753

Cutter Drum 072 0633 1133 Right

515 0681

507 0486 Cutter Dru 050 0722 0692

Left 507 0513

505 0714 Rear Controls 085 0856 0989

Right 505 0980

522 3333 Upper 279 3315 0841

Conveyor 522 2244

518 1742 Rear Controls 170 1750 0973

Left 520 1664

Notes All gravimetric results are field-blan corrected

16

Table 5 Low-Flow and pDR Area Sample Results

Sampling Location

Operator

Cutter Drum Right

Cutter Drum Left

Rear Controls

Right

Upper Conveyor

Rear Controls

Left

Sample Time (min)

505

505

498

499

506

504

498

498

507

507

506

508

Gravimetrc Respirable

Dust (mgm3)

0964

1043

1938

1709

2882

1850

0519

0775

3169

2184

2696

2545

Payne and Dolan October 9 2003

Average Respirable

Dust at Location (mwm3)

100

182

288

pinched hose

065

268

262

pDR Respirable

Dust (mglm3)

0989

1839

2939

0746

3297

2459

GravimetrcpDR Ratio

1015

0992

0980

0867

0812

1066

Notes All gravimetric results are field-blank corrected

17

Table 2 Results of Personal Breathg Zone Samples Payne and Dolan October 92003

Respirable Respirable Respirable OSHA RespirableTime Percent VolumeJob Dust Quarz Dust PEL Quarz(min) Quarz (L)(mg) (mg) (mgm3) (mgm3) (mgm3) UniJetQ 11005 Nozzle

Operator 138 13 008 600 572 227 125 014 Foreman 117 04 (003) (750) 499 080 105 (006) Rear Control 105 023 (001) (435) 435 053 158 (002)

~ UnigraveJet91lO08Nozzle ~ Ooerator HI 069 003 493 460

l50 144 001

Foreman 114 022 (001 ) (455) 486

045 153 XOOL) Rear Control 111 059 (003) (508) 460 128 14L fO07)

d Dniecirct~ 11008 Nozzle f

Operator 132 069 005 681 547 L26 113 009 Forerraringn 125 Q44 003 750 533

OS3 105 006 ~

Rear Control 134 031 (001) (323) 556 OS6 Ln (002) UniJet 11005 Nozzle

Operator 114 093 005 495 472 197 144 010 Foreman 111 021 (001) (476) 473 044 148 (002) Rear Control 107 072 003 472 444 162 149 008

Notes All results are field-blan corrected

ND indicates a result less than the limit of detection for this method of 10 lJg of quarz per sample Results in parentheses indicate a semi-quantitative value between the limit of detection and the limit of quantitation

14

Tab

le 3

Hig

h~Fl

ow A

rea

Sam

ple

Res

ults

Pa

yne

and

Dol

an

Oct

ober

9 2

003

Res

pira

ble

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ble

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i V

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n N

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p ~Y~

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Upp

er C

onve

yor

Uni

Jetlszlig

1100

5 1

8 0

11

Not

es A

ll re

sults

are

fie

ld-b

lan

corr

ecte

d N

O in

dica

tes

a re

sult

less

than

the

lit o

f de

tect

ion

for

tls m

etho

d of

1 O

iexclg

of q

uar

per

sample Results in parntheses indicate a semi-quatitative value between the lit of detection and the lit of quantitation

Table 4 Low-Flow and pDR Area Sample Results Payne and Dolan October 8 2003

Sampling Location

Sample Time (min)

Gravimetrc Respirable Dust

(mglm3)

Average Respirable

Dust at Location (mgm3)

pDR Respirable Dust

(mglm3)

GravimetrcpDR Ratio

498 0309

Operator 032 0216 1469

501 0325

514 0753

Cutter Drum 072 0633 1133 Right

515 0681

507 0486 Cutter Dru 050 0722 0692

Left 507 0513

505 0714 Rear Controls 085 0856 0989

Right 505 0980

522 3333 Upper 279 3315 0841

Conveyor 522 2244

518 1742 Rear Controls 170 1750 0973

Left 520 1664

Notes All gravimetric results are field-blan corrected

16

Table 5 Low-Flow and pDR Area Sample Results

Sampling Location

Operator

Cutter Drum Right

Cutter Drum Left

Rear Controls

Right

Upper Conveyor

Rear Controls

Left

Sample Time (min)

505

505

498

499

506

504

498

498

507

507

506

508

Gravimetrc Respirable

Dust (mgm3)

0964

1043

1938

1709

2882

1850

0519

0775

3169

2184

2696

2545

Payne and Dolan October 9 2003

Average Respirable

Dust at Location (mwm3)

100

182

288

pinched hose

065

268

262

pDR Respirable

Dust (mglm3)

0989

1839

2939

0746

3297

2459

GravimetrcpDR Ratio

1015

0992

0980

0867

0812

1066

Notes All gravimetric results are field-blank corrected

17

Tab

le 3

Hig

h~Fl

ow A

rea

Sam

ple

Res

ults

Pa

yne

and

Dol

an

Oct

ober

9 2

003

Res

pira

ble

Res

pira

ble

Res

pira

ble

Res

pira

ble

T

i V

olum

ePe

rcen

t D

ust

Qua

Loc

atio

n N

ozze

D

ust

Qu

Qua

(m

iute

s)

(L)

(mg

m3)

(m

gm3)

(mg)

(m

g)

Ope

rato

r U

niet

(szlig 1

1005

N

D

- ~

ii~

-

~~

i

~2

S

iquest

(3

~

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135

~ s

k

il

Q

iexcllf

1 I

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t

~

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negrave~

llOO

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)

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t i i ~

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a o

r c7

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1

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559

322

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11

132

Upp

er C

onve

yor

Uni

Jetlszlig

1100

5 1

8 0

11

Not

es A

ll re

sults

are

fie

ld-b

lan

corr

ecte

d N

O in

dica

tes

a re

sult

less

than

the

lit o

f de

tect

ion

for

tls m

etho

d of

1 O

iexclg

of q

uar

per

sample Results in parntheses indicate a semi-quatitative value between the lit of detection and the lit of quantitation

Table 4 Low-Flow and pDR Area Sample Results Payne and Dolan October 8 2003

Sampling Location

Sample Time (min)

Gravimetrc Respirable Dust

(mglm3)

Average Respirable

Dust at Location (mgm3)

pDR Respirable Dust

(mglm3)

GravimetrcpDR Ratio

498 0309

Operator 032 0216 1469

501 0325

514 0753

Cutter Drum 072 0633 1133 Right

515 0681

507 0486 Cutter Dru 050 0722 0692

Left 507 0513

505 0714 Rear Controls 085 0856 0989

Right 505 0980

522 3333 Upper 279 3315 0841

Conveyor 522 2244

518 1742 Rear Controls 170 1750 0973

Left 520 1664

Notes All gravimetric results are field-blan corrected

16

Table 5 Low-Flow and pDR Area Sample Results

Sampling Location

Operator

Cutter Drum Right

Cutter Drum Left

Rear Controls

Right

Upper Conveyor

Rear Controls

Left

Sample Time (min)

505

505

498

499

506

504

498

498

507

507

506

508

Gravimetrc Respirable

Dust (mgm3)

0964

1043

1938

1709

2882

1850

0519

0775

3169

2184

2696

2545

Payne and Dolan October 9 2003

Average Respirable

Dust at Location (mwm3)

100

182

288

pinched hose

065

268

262

pDR Respirable

Dust (mglm3)

0989

1839

2939

0746

3297

2459

GravimetrcpDR Ratio

1015

0992

0980

0867

0812

1066

Notes All gravimetric results are field-blank corrected

17

Table 4 Low-Flow and pDR Area Sample Results Payne and Dolan October 8 2003

Sampling Location

Sample Time (min)

Gravimetrc Respirable Dust

(mglm3)

Average Respirable

Dust at Location (mgm3)

pDR Respirable Dust

(mglm3)

GravimetrcpDR Ratio

498 0309

Operator 032 0216 1469

501 0325

514 0753

Cutter Drum 072 0633 1133 Right

515 0681

507 0486 Cutter Dru 050 0722 0692

Left 507 0513

505 0714 Rear Controls 085 0856 0989

Right 505 0980

522 3333 Upper 279 3315 0841

Conveyor 522 2244

518 1742 Rear Controls 170 1750 0973

Left 520 1664

Notes All gravimetric results are field-blan corrected

16

Table 5 Low-Flow and pDR Area Sample Results

Sampling Location

Operator

Cutter Drum Right

Cutter Drum Left

Rear Controls

Right

Upper Conveyor

Rear Controls

Left

Sample Time (min)

505

505

498

499

506

504

498

498

507

507

506

508

Gravimetrc Respirable

Dust (mgm3)

0964

1043

1938

1709

2882

1850

0519

0775

3169

2184

2696

2545

Payne and Dolan October 9 2003

Average Respirable

Dust at Location (mwm3)

100

182

288

pinched hose

065

268

262

pDR Respirable

Dust (mglm3)

0989

1839

2939

0746

3297

2459

GravimetrcpDR Ratio

1015

0992

0980

0867

0812

1066

Notes All gravimetric results are field-blank corrected

17

Table 5 Low-Flow and pDR Area Sample Results

Sampling Location

Operator

Cutter Drum Right

Cutter Drum Left

Rear Controls

Right

Upper Conveyor

Rear Controls

Left

Sample Time (min)

505

505

498

499

506

504

498

498

507

507

506

508

Gravimetrc Respirable

Dust (mgm3)

0964

1043

1938

1709

2882

1850

0519

0775

3169

2184

2696

2545

Payne and Dolan October 9 2003

Average Respirable

Dust at Location (mwm3)

100

182

288

pinched hose

065

268

262

pDR Respirable

Dust (mglm3)

0989

1839

2939

0746

3297

2459

GravimetrcpDR Ratio

1015

0992

0980

0867

0812

1066

Notes All gravimetric results are field-blank corrected

17

Tab

le 6

Sum

ar o

f Adj

uste

d pD

R D

ust C

once

ntrt

ions

for

Eac

h C

ut

Payn

e an

d D

olan

O

ctob

er 8

and

9 2

003

A

vera

ge

Ave

rage

wat

erfl

Ave

rage

wat

er p

ress

me

Cu

U O

p t C

utte

r D

n R

ear

Con

trol

s fo

r cu

tow i-te (l t pper era or 3 3 3)

Cut Cut Trucks (llm ) bs per sq men) Sp d C ( I 3) (mgm ) (mgm ) (mgm

ime

a e

(mlm

i) (m

gr)

T Lad d ga om ee onveyoi mg m

~tte

r U

pper

Cut

ter

uPP

~er

Low

er L

eft R

ight

~ft

Rig

htDr Conveyor Dru Conveyor Conveyor

~~ 1 i r iexclJd- ~ ~IJ ~EA_~~ t r t tpound~~- J ~(~r~~ iexcl~~r l Jir-~~~ ~i~ ~ ~ri ~ffW~ ~ tiC5f

_~ u J ~ ~~I oM l u _lamp~_It~~~~~_~~))iJltW(~ WJ ~~~

1 26 9 6 4 50 38 30 71 363 035 032 113 231 198 162

2 14 5 6 4 50 30 20 70 566 079 085 254 591 413 331

3 63

26

6 4

50 4

0 25

14

7 5

18 0

68

060

14

0 2

62 1

50

199

4 73 35 6 4 45 35 20 92 748 016 014 088 059 14 176

5 58 21 6 4 na 11a nla 95 047 044 200 039 519 039 148

6 35 205 6 4 50 35 25 130 025 045 059 040 149 044 060

7 26 7 6 4 50 40 25 nla 050 002 010 016 020 005 017

8 74

39

6 4

50 3

5 25

11

0 3

74 uuml

52

041

10

7 1

60 0

79

136

~ ~

iexcl

~~~~

-~

~~

~~

iexcl~

~szlig

igrave~

~iexcl

~~

i

~~

~~

~~

~

t

v4~

~

~~

~

I~~

~l

~~

l~1 16 7 6 4 nla 35 nla 90 131 16 680 126 454 034 257

2 61 23 6 4 49 38 25 71 677 18 400 275 319 029 313

2A 3

5 16

9 3

7 3

5 28

22

74

084

20

5 9

04 2

72

605

17

2 3

74

3 76 35 9 37 35 28 22 71 391 095 372 219 381 036 2A9

4 30 15 9 37 nla nla nla lOA 743 14 240 387 251 092 304

4A 4

6 19

6 4

45

35 2

0 52

19

0 1

83 3

76

289

47

7 2

29 2

91

5 39 18 6 4 40 35 20 91 399 143 277 307 316 19 260

~_

~~

~~

m~

~iexcl

~

~~

c

~~

~1

~

~iexclq

~iJ ~1I ~t~~~~~z~~~ ~ia ~yiexcl~~t~~ rlsect~jtiocircIacutei~~~~~

Nozze Tota Cu Averges Time Weigraveghted Averages

Uni

etlB

162

67

6 4

46 3

6 22

72

41

8 1

65 3

91

272

37

6 1

08 2

88

1100

5U

nigraveet

l 1

41 6

6 9

37

35 2

8 22

79

39

0 1

26 4

76

268

40

9 0

81 2

92

11

008

Milig Machie Cuts

Table 7 Descriptions of Pa

yne

and

Dol

an

Oct

ober

9 2

003

GPS

Average speed

Ave

rage

A

vera

geE

laps

ed

Digraves

tace

A

vera

ge

from tie stdy

Cut

C

ut

Noz

zle

Cut

ID

T

ime

Cut

V

eloc

ity

Dep

th

Wid

th

Typ

e (m

iute

s)

(fee

t)

(ftm

in)

(inc

hes)

(i

nche

s)

mm

iacute ft

mi

1 17

6

446

253

9

295

9

98

Unigrave

Jetll

110

05

Bac

k up

5

9 14

12

238

7 7

1 23

3

74

98

Uniel 11 005

2 67

3

1255

18

6

243

9

5 98

U

nicircJe

tlI 1

1008

2A

341

69

0 20

2

74

B

ack

up

72

1893

26

48

3 68

5

1805

26

4

71

232

7

8 98

U

niJe

tl11

008

-C

Bac

k up

7

1 18

77

264

9 4

287

11

17

390

10

4

34

67

Dni

J et

~ 1

1008

449

77

1 17

2

52

171

10

9

97

Uni

et(szlig

1 i

005

4A

Bac

k up

6

8 17

78

263

4

5 42

8

1582

36

9

94

307

6

3 98

U

niJe

tl 1

1 00

5

Not

es B

acku

mea

n ba

ckig

the

mil

up th

e bi

to b

egi a

new

cut

Ela

psed

ties

are

act

ual o

pera

tig ti

es

Tab

le 8

Res

pigravera

ble

Dus

t Mea

n by

Uni

etlI

Noz

zle

Typ

e

Payn

e an

d D

olan

O

ctob

er 9

200

3 G

eorn

G

eorn

1100

5 N

umbe

r of

Fr

actio

n of

M

ean

Num

ber

of

Frac

tion

of

Mea

n M

ean

Mea

n G

MI

(SD

)11

008

(GSD

)11

005

11 0

05

(SD

) 11

008

1100

8 (G

SD)

1100

8 Sa

mpl

es

Sam

ples

~ P

EL

11

005

1100

8Sa

mpl

es

Sam

ples

~ P

EL

11

005

G

M

125

(20

7)

15125= 12

050

1

59(1

15)

1

50(2

39)

17

059

2

05(1

58)

18

Tab

le 9

Res

pigravera

ble

Dus

t Mea

ns a

nd G

eom

etrc

Mea

n by

Are

a or

Per

sona

l Sam

ple

Payn

e an

d D

olan

October 8 an 9~ 2003

Frac

tion

Gem

G

eOID

Frac

tion

Unigrave

JetII

110

05~ c

U

niJ

etII

M

ean

Unigrave

JetI

I M

ean

Mea

n M

ean

of

of

Pers

ona

11 0

05

Uni

etII

(S

D)~

11

008

Uni

J et

(8

(SD

)

(GSD

) (G

SD)

G

M

Uni

JetI

I 11

Ouml08

Uni

etII

N

umbe

r U

niJe

tII

Dat

e or

Are

a N

umbe

r U

nigraveJe

tII

Uni

etII

11 0

05

1100

8 G

MSa

mpl

e of

11

005

of

1100

8 11

008

Sani

ples

Sa

mpl

es

11 0

05

Sam

ples

Sa

mpl

es~P

EL

~P

EL

0

40(2

45)

10-0

8 P

9 0

22

058

(05

8)

089

(16

4)

105

08

9=1

1810

-09

P 6

050

1

27(0

78)

6

033

0

98(0

43)

1

05(2

02)

10-0

9 A

11

0

64

247

(17

7)

12

058

1

90(

129

) 1

82(2

52)

1

47(2

20)

1

8211

47=

124

Tab

le 1

0 R

espi

rabl

e D

ust M

ean

and

Geo

met

rc M

ean

by W

orke

r Pa

yne

and

Dol

an

Oct

ober

8 a

nd 9

200

3 G

eom

G

eom

N

umbe

r N

umbe

rM

ean(

SD)

M

ean(

SD)

M

ean

Mea

n U

niJe

tQ 1

1005

GM

Iof

of

Uni

etQ

D

niJe

tQ

(GSD

)

(GSD

)

Uni

etQ

110

08D

ate

Wor

ker

Unigrave

JetQ

U

niJe

tQ

1100

5

1100

8 U

niet

Ol

Unigrave

Jet~

G

Mn0

05

1100

8 11

005

11 0

08

Sam

ples

Sa

mpl

es

10-0

8 Fo

rem

an

3 1

10(0

83)

0

77(3

27)

0

24(1

61)

10

-08

Ope

rato

r 3

026

(01

0)

0

33(2

02)

10

-08

Slaringd

Ste

er

3 0

39(0

25)

2

064

(02

7)

059

(15

3)

061

(15

4)

059

06

1=0

9710

-09

Fore

man

2

062

(02

5)

2 1

38(0

17)

211(11 1)

137

(11

3)

211

13

7=1

5410

-09

2

212

(02

1)O

pera

tor

093

08

5=1

0910

-09

Rea

r C

ontr

ol

2 1

08(0

77)

2

092

(05

1)

093

(22

0)

085

(17

9)

t

Tab

le 1

1 R

espi

rabl

e D

ust M

ean

and

Geo

met

rc M

ean

by L

ocat

ion

Payn

e an

d D

olan

O

ctob

er 8

and

9 2

003

Uni

Jetszlig

U

niet

(szligu

Geo

m M

ean

11 0

05

Mea

n(SD

) 11

008

Mea

n(SD

) Gem Mean

(GSD

)

Uni

etiI

II00

5GM

D

ate

Loc

atio

n N

umbe

r U

niJe

tiI

Num

ber

Uni

Jet(

szlig (G

SD)

U

niet

iI

Uni

JetiI

i 10

08 G

Mof

11

005

of

1100

8 U

niJ

et(szlig

110

05

1100

8Sa

mpl

es

Sam

ples

10

-09

Cut

ter

Dr

Lef

t 2

248

(12

6)

2 2

46(1

25)

2

31(1

70)

2

29(1

71)

2

312

29=

101

10

-09

Rea

r C

ontr

ols

Lef

t 2

400

061

)

2 2

73(0

46)

3

83(1

51)

2

71 (

118

) 3

832

71=

141

10

-09

Ope

rato

r 1

148

0 2

108

(03

9)

lA8(

) 1

04(1

45)

1

481

041

42

10-0

9 C

utte

r D

ru R

ight

2

120

(06

6)

2 0

96(0

28)

1

10(1

79)

0

94(1

35)

1

100

94=

117

10

-09

Upper Conveyor

2 4

47(1

76)

2

372

(07

3)

429

(15

0)

368

(12

2)

429

36

8=1

17

10-0

9 R

ear

Con

trol

s R

ight

2

070

(06

4)

2 0

47(0

14)

0

53(3

03)

0

46(1

36)

0

530

46=

i 1

5

~

Noz

zle

Typ

e Pa

yne

and

Dol

an

Oct

ober

9 2

003

Geo

m M

ean

Geo

m M

ean

Table 12 Respirable Quar Mean by UnietQi

Num

ber

of 1

1005

M

ean

(SD

) N

umbe

r of

110

08

Mea

n (S

D)

1100

5 G

MI

(GSD

) (G

SD)

Sam

ples

1

1005

Sa

mpl

es

1 10

08

1100

8 G

M11

005

1100

8 17

0

13(0

16)

18

0

10(0

094

) 0

078(

269

) 0

067(

264

) 0

780

67=

116

Tab

le 1

3 R

espi

rabl

e Q

uar

Mea

n an

d G

eom

etrc

Mea

n by

Are

a or

Per

sona

l Sam

ple

Payn

e an

d D

olan

O

ctob

er 8

and

92

003

Uni

Jetl

U

niJe

t(I

Geo

m M

ean

Geo

m M

ean

Pers

ona

1100

5 11

008

Mea

n (S

D)

Mea

n (S

D)

(GSD

) D

nigraveJ

etQ

i 1 i

005

GM

(G

SD)

Dat

e or

Are

a N

umbe

r N

umbe

rU

niJe

ti11

005

Uni

JetlI

1100

8 U

niet

i

Uni

JetQ

U

niet

i110

08 G

MSa

mpl

e of

of

11

005

11 0

08

~ Sa

mpl

es

Sam

ples

LUgrave

10

-08

P 9

004

0(0

039)

10

~09

P 6

006

9(0

043)

6

005

4(0

026)

0

057(

202

) 0

048(

181

) 0

057

004

8=1

19

10-0

9 A

11

0

16(0

19)

12

0

13(0

11)

0

092(

303

) 0

080(

299

) 0

092

100

80=

1 1

5

Dat

e W

orke

r

10-0

8 Fo

rem

a 10

-08

Ope

rato

r 10

-08

Skid

Ste

er

10-0

9 Fo

rem

an

10-0

9 O

pera

tor

10-0

9 R

ear

Con

trol

s

~

Tab

le 1

4 R

espIgrave

Tab

le Q

ua M

eans

and

Geo

met

rc M

ean

by W

orke

r

Payn

e an

d D

olan

O

ctob

er 8

and

9 2

003

G

eom

Num

ber

Num

ber

Gom

M

ean

of

Mea

n(SD

) of

M

ean

Mea

n(SD

) (G

SD)

Uni

et(I

U

nigraveet

(szlig

Uni

Jet(

szlig (G

SD)

Uni

Jet(

szlig 11

008

Uiugrave

Jet(

szlig11

005

1100

5 11

008

Unigrave

et(

szlig 1

1008

Sa

mpl

es

Sam

ples

11

005

3 0

072(

005

5)

3 0

046(

403

) 3

001

8(0

0062

) 3

001

7(1

46)

3 0

029(

002

5)

3 0

023(

229

) 2

003

9(0

022)

2

004

1(0

029)

0

035(

182

) 0

036(

218

) 2

012

(00

28)

2 0

080(

000

85)

012

(12

7)

008

0(1

11)

2 0

052(

003

5)

2 0

041(

002

2)

004

6(2

06)

003

8(1

77)

Uni

Jet4

110

05 G

MI

Uni

Jet(

szlig 11

008

GM

003

50

036=

97

012

00

80=

15

004

60

038=

121

Tab

le 1

5 R

espi

rabl

e Q

uar

Mea

n an

d G

eom

etrc

Mea

n by

Loc

atio

n Pa

yne

and

Dol

an

Oct

ober

8 a

nd 9

200

3 U

niet

lszlig

Unicirc

Jetauml

G

eom

Geo

m

1100

5 M

ean(

SD)

1100

8 M

ean(

SD)

M

ean

Mea

n (G

SD

) U

niet

lI 1

1005

GM

I D

ate

Loc

atio

n N

umbe

r U

niet

lI

Num

ber

Unicirc

J et

tj (G

SD)

Uni

JetC

I

Uni

ettj

1100

8 G

Mof

11

005

of

1100

8

Uni

etlI

1

i 005

Sa

mpl

es

Sam

ples

11

008

014

(17

2)

013

01

4=9

310

-09

Cut

ter

Dr

Lef

t 2

014

(00

93)

2 0

15(0

079

)

013

(20

1)

018

(13

1)

018

(1

38)

018

01

8==

1i 0

-09

Rea

r C

ontr

ols

Left

2

018

(00

50)

2 0

19(0

059

) 0

0490

2

003

3(0

028)

0

049

002

6(2

67)

004

90

026=

188

10-0

9 O

pera

tor

1

005

9(2

11)

004

90

059=

083

10-0

9 C

utte

r D

r R

ight

2

005

4(0

034)

2

0

067(

004

6)

004

9(1

94)

029

(00

96)

036

(23

7)

028

(14

1)

036

02

8=1

2910

-09

Upper Conveyor

2 0

43(0

33)

2

002

2(1

85)

002

4(1

97)

002

20

024=

92

i 0-0

9 R

ear

Con

trol

s R

ight

2

0

024

(00

14)

2 0

027(

001

7)

~ (r

Figure 1 Water flow meterS

Figue 2 Cutter drm water supply pressire gauge

27

Figure 3 GPS igravenstniment location

iB

Figure 4 Area sampling array

aq

-- PLAN VIEgraveW

SIDE VIEW

KEY Acirc Machine mounted dust

monitoring locations

3D VIEW I Milling crew dustmonitoring locations

(shown igraven plan view only)

Figure 5 Area Sample Locations

3Otilde

Figure 6 Operator and foreman Foreman is operating right rear controls

31

Figure 7 Position of operator and locatigraveons of personal and area samplers

Milig Machie Cuts

Table 7 Descriptions of Pa

yne

and

Dol

an

Oct

ober

9 2

003

GPS

Average speed

Ave

rage

A

vera

geE

laps

ed

Digraves

tace

A

vera

ge

from tie stdy

Cut

C

ut

Noz

zle

Cut

ID

T

ime

Cut

V

eloc

ity

Dep

th

Wid

th

Typ

e (m

iute

s)

(fee

t)

(ftm

in)

(inc

hes)

(i

nche

s)

mm

iacute ft

mi

1 17

6

446

253

9

295

9

98

Unigrave

Jetll

110

05

Bac

k up

5

9 14

12

238

7 7

1 23

3

74

98

Uniel 11 005

2 67

3

1255

18

6

243

9

5 98

U

nicircJe

tlI 1

1008

2A

341

69

0 20

2

74

B

ack

up

72

1893

26

48

3 68

5

1805

26

4

71

232

7

8 98

U

niJe

tl11

008

-C

Bac

k up

7

1 18

77

264

9 4

287

11

17

390

10

4

34

67

Dni

J et

~ 1

1008

449

77

1 17

2

52

171

10

9

97

Uni

et(szlig

1 i

005

4A

Bac

k up

6

8 17

78

263

4

5 42

8

1582

36

9

94

307

6

3 98

U

niJe

tl 1

1 00

5

Not

es B

acku

mea

n ba

ckig

the

mil

up th

e bi

to b

egi a

new

cut

Ela

psed

ties

are

act

ual o

pera

tig ti

es

Tab

le 8

Res

pigravera

ble

Dus

t Mea

n by

Uni

etlI

Noz

zle

Typ

e

Payn

e an

d D

olan

O

ctob

er 9

200

3 G

eorn

G

eorn

1100

5 N

umbe

r of

Fr

actio

n of

M

ean

Num

ber

of

Frac

tion

of

Mea

n M

ean

Mea

n G

MI

(SD

)11

008

(GSD

)11

005

11 0

05

(SD

) 11

008

1100

8 (G

SD)

1100

8 Sa

mpl

es

Sam

ples

~ P

EL

11

005

1100

8Sa

mpl

es

Sam

ples

~ P

EL

11

005

G

M

125

(20

7)

15125= 12

050

1

59(1

15)

1

50(2

39)

17

059

2

05(1

58)

18

Tab

le 9

Res

pigravera

ble

Dus

t Mea

ns a

nd G

eom

etrc

Mea

n by

Are

a or

Per

sona

l Sam

ple

Payn

e an

d D

olan

October 8 an 9~ 2003

Frac

tion

Gem

G

eOID

Frac

tion

Unigrave

JetII

110

05~ c

U

niJ

etII

M

ean

Unigrave

JetI

I M

ean

Mea

n M

ean

of

of

Pers

ona

11 0

05

Uni

etII

(S

D)~

11

008

Uni

J et

(8

(SD

)

(GSD

) (G

SD)

G

M

Uni

JetI

I 11

Ouml08

Uni

etII

N

umbe

r U

niJe

tII

Dat

e or

Are

a N

umbe

r U

nigraveJe

tII

Uni

etII

11 0

05

1100

8 G

MSa

mpl

e of

11

005

of

1100

8 11

008

Sani

ples

Sa

mpl

es

11 0

05

Sam

ples

Sa

mpl

es~P

EL

~P

EL

0

40(2

45)

10-0

8 P

9 0

22

058

(05

8)

089

(16

4)

105

08

9=1

1810

-09

P 6

050

1

27(0

78)

6

033

0

98(0

43)

1

05(2

02)

10-0

9 A

11

0

64

247

(17

7)

12

058

1

90(

129

) 1

82(2

52)

1

47(2

20)

1

8211

47=

124

Tab

le 1

0 R

espi

rabl

e D

ust M

ean

and

Geo

met

rc M

ean

by W

orke

r Pa

yne

and

Dol

an

Oct

ober

8 a

nd 9

200

3 G

eom

G

eom

N

umbe

r N

umbe

rM

ean(

SD)

M

ean(

SD)

M

ean

Mea

n U

niJe

tQ 1

1005

GM

Iof

of

Uni

etQ

D

niJe

tQ

(GSD

)

(GSD

)

Uni

etQ

110

08D

ate

Wor

ker

Unigrave

JetQ

U

niJe

tQ

1100

5

1100

8 U

niet

Ol

Unigrave

Jet~

G

Mn0

05

1100

8 11

005

11 0

08

Sam

ples

Sa

mpl

es

10-0

8 Fo

rem

an

3 1

10(0

83)

0

77(3

27)

0

24(1

61)

10

-08

Ope

rato

r 3

026

(01

0)

0

33(2

02)

10

-08

Slaringd

Ste

er

3 0

39(0

25)

2

064

(02

7)

059

(15

3)

061

(15

4)

059

06

1=0

9710

-09

Fore

man

2

062

(02

5)

2 1

38(0

17)

211(11 1)

137

(11

3)

211

13

7=1

5410

-09

2

212

(02

1)O

pera

tor

093

08

5=1

0910

-09

Rea

r C

ontr

ol

2 1

08(0

77)

2

092

(05

1)

093

(22

0)

085

(17

9)

t

Tab

le 1

1 R

espi

rabl

e D

ust M

ean

and

Geo

met

rc M

ean

by L

ocat

ion

Payn

e an

d D

olan

O

ctob

er 8

and

9 2

003

Uni

Jetszlig

U

niet

(szligu

Geo

m M

ean

11 0

05

Mea

n(SD

) 11

008

Mea

n(SD

) Gem Mean

(GSD

)

Uni

etiI

II00

5GM

D

ate

Loc

atio

n N

umbe

r U

niJe

tiI

Num

ber

Uni

Jet(

szlig (G

SD)

U

niet

iI

Uni

JetiI

i 10

08 G

Mof

11

005

of

1100

8 U

niJ

et(szlig

110

05

1100

8Sa

mpl

es

Sam

ples

10

-09

Cut

ter

Dr

Lef

t 2

248

(12

6)

2 2

46(1

25)

2

31(1

70)

2

29(1

71)

2

312

29=

101

10

-09

Rea

r C

ontr

ols

Lef

t 2

400

061

)

2 2

73(0

46)

3

83(1

51)

2

71 (

118

) 3

832

71=

141

10

-09

Ope

rato

r 1

148

0 2

108

(03

9)

lA8(

) 1

04(1

45)

1

481

041

42

10-0

9 C

utte

r D

ru R

ight

2

120

(06

6)

2 0

96(0

28)

1

10(1

79)

0

94(1

35)

1

100

94=

117

10

-09

Upper Conveyor

2 4

47(1

76)

2

372

(07

3)

429

(15

0)

368

(12

2)

429

36

8=1

17

10-0

9 R

ear

Con

trol

s R

ight

2

070

(06

4)

2 0

47(0

14)

0

53(3

03)

0

46(1

36)

0

530

46=

i 1

5

~

Noz

zle

Typ

e Pa

yne

and

Dol

an

Oct

ober

9 2

003

Geo

m M

ean

Geo

m M

ean

Table 12 Respirable Quar Mean by UnietQi

Num

ber

of 1

1005

M

ean

(SD

) N

umbe

r of

110

08

Mea

n (S

D)

1100

5 G

MI

(GSD

) (G

SD)

Sam

ples

1

1005

Sa

mpl

es

1 10

08

1100

8 G

M11

005

1100

8 17

0

13(0

16)

18

0

10(0

094

) 0

078(

269

) 0

067(

264

) 0

780

67=

116

Tab

le 1

3 R

espi

rabl

e Q

uar

Mea

n an

d G

eom

etrc

Mea

n by

Are

a or

Per

sona

l Sam

ple

Payn

e an

d D

olan

O

ctob

er 8

and

92

003

Uni

Jetl

U

niJe

t(I

Geo

m M

ean

Geo

m M

ean

Pers

ona

1100

5 11

008

Mea

n (S

D)

Mea

n (S

D)

(GSD

) D

nigraveJ

etQ

i 1 i

005

GM

(G

SD)

Dat

e or

Are

a N

umbe

r N

umbe

rU

niJe

ti11

005

Uni

JetlI

1100

8 U

niet

i

Uni

JetQ

U

niet

i110

08 G

MSa

mpl

e of

of

11

005

11 0

08

~ Sa

mpl

es

Sam

ples

LUgrave

10

-08

P 9

004

0(0

039)

10

~09

P 6

006

9(0

043)

6

005

4(0

026)

0

057(

202

) 0

048(

181

) 0

057

004

8=1

19

10-0

9 A

11

0

16(0

19)

12

0

13(0

11)

0

092(

303

) 0

080(

299

) 0

092

100

80=

1 1

5

Dat

e W

orke

r

10-0

8 Fo

rem

a 10

-08

Ope

rato

r 10

-08

Skid

Ste

er

10-0

9 Fo

rem

an

10-0

9 O

pera

tor

10-0

9 R

ear

Con

trol

s

~

Tab

le 1

4 R

espIgrave

Tab

le Q

ua M

eans

and

Geo

met

rc M

ean

by W

orke

r

Payn

e an

d D

olan

O

ctob

er 8

and

9 2

003

G

eom

Num

ber

Num

ber

Gom

M

ean

of

Mea

n(SD

) of

M

ean

Mea

n(SD

) (G

SD)

Uni

et(I

U

nigraveet

(szlig

Uni

Jet(

szlig (G

SD)

Uni

Jet(

szlig 11

008

Uiugrave

Jet(

szlig11

005

1100

5 11

008

Unigrave

et(

szlig 1

1008

Sa

mpl

es

Sam

ples

11

005

3 0

072(

005

5)

3 0

046(

403

) 3

001

8(0

0062

) 3

001

7(1

46)

3 0

029(

002

5)

3 0

023(

229

) 2

003

9(0

022)

2

004

1(0

029)

0

035(

182

) 0

036(

218

) 2

012

(00

28)

2 0

080(

000

85)

012

(12

7)

008

0(1

11)

2 0

052(

003

5)

2 0

041(

002

2)

004

6(2

06)

003

8(1

77)

Uni

Jet4

110

05 G

MI

Uni

Jet(

szlig 11

008

GM

003

50

036=

97

012

00

80=

15

004

60

038=

121

Tab

le 1

5 R

espi

rabl

e Q

uar

Mea

n an

d G

eom

etrc

Mea

n by

Loc

atio

n Pa

yne

and

Dol

an

Oct

ober

8 a

nd 9

200

3 U

niet

lszlig

Unicirc

Jetauml

G

eom

Geo

m

1100

5 M

ean(

SD)

1100

8 M

ean(

SD)

M

ean

Mea

n (G

SD

) U

niet

lI 1

1005

GM

I D

ate

Loc

atio

n N

umbe

r U

niet

lI

Num

ber

Unicirc

J et

tj (G

SD)

Uni

JetC

I

Uni

ettj

1100

8 G

Mof

11

005

of

1100

8

Uni

etlI

1

i 005

Sa

mpl

es

Sam

ples

11

008

014

(17

2)

013

01

4=9

310

-09

Cut

ter

Dr

Lef

t 2

014

(00

93)

2 0

15(0

079

)

013

(20

1)

018

(13

1)

018

(1

38)

018

01

8==

1i 0

-09

Rea

r C

ontr

ols

Left

2

018

(00

50)

2 0

19(0

059

) 0

0490

2

003

3(0

028)

0

049

002

6(2

67)

004

90

026=

188

10-0

9 O

pera

tor

1

005

9(2

11)

004

90

059=

083

10-0

9 C

utte

r D

r R

ight

2

005

4(0

034)

2

0

067(

004

6)

004

9(1

94)

029

(00

96)

036

(23

7)

028

(14

1)

036

02

8=1

2910

-09

Upper Conveyor

2 0

43(0

33)

2

002

2(1

85)

002

4(1

97)

002

20

024=

92

i 0-0

9 R

ear

Con

trol

s R

ight

2

0

024

(00

14)

2 0

027(

001

7)

~ (r

Figure 1 Water flow meterS

Figue 2 Cutter drm water supply pressire gauge

27

Figure 3 GPS igravenstniment location

iB

Figure 4 Area sampling array

aq

-- PLAN VIEgraveW

SIDE VIEW

KEY Acirc Machine mounted dust

monitoring locations

3D VIEW I Milling crew dustmonitoring locations

(shown igraven plan view only)

Figure 5 Area Sample Locations

3Otilde

Figure 6 Operator and foreman Foreman is operating right rear controls

31

Figure 7 Position of operator and locatigraveons of personal and area samplers

Tab

le 8

Res

pigravera

ble

Dus

t Mea

n by

Uni

etlI

Noz

zle

Typ

e

Payn

e an

d D

olan

O

ctob

er 9

200

3 G

eorn

G

eorn

1100

5 N

umbe

r of

Fr

actio

n of

M

ean

Num

ber

of

Frac

tion

of

Mea

n M

ean

Mea

n G

MI

(SD

)11

008

(GSD

)11

005

11 0

05

(SD

) 11

008

1100

8 (G

SD)

1100

8 Sa

mpl

es

Sam

ples

~ P

EL

11

005

1100

8Sa

mpl

es

Sam

ples

~ P

EL

11

005

G

M

125

(20

7)

15125= 12

050

1

59(1

15)

1

50(2

39)

17

059

2

05(1

58)

18

Tab

le 9

Res

pigravera

ble

Dus

t Mea

ns a

nd G

eom

etrc

Mea

n by

Are

a or

Per

sona

l Sam

ple

Payn

e an

d D

olan

October 8 an 9~ 2003

Frac

tion

Gem

G

eOID

Frac

tion

Unigrave

JetII

110

05~ c

U

niJ

etII

M

ean

Unigrave

JetI

I M

ean

Mea

n M

ean

of

of

Pers

ona

11 0

05

Uni

etII

(S

D)~

11

008

Uni

J et

(8

(SD

)

(GSD

) (G

SD)

G

M

Uni

JetI

I 11

Ouml08

Uni

etII

N

umbe

r U

niJe

tII

Dat

e or

Are

a N

umbe

r U

nigraveJe

tII

Uni

etII

11 0

05

1100

8 G

MSa

mpl

e of

11

005

of

1100

8 11

008

Sani

ples

Sa

mpl

es

11 0

05

Sam

ples

Sa

mpl

es~P

EL

~P

EL

0

40(2

45)

10-0

8 P

9 0

22

058

(05

8)

089

(16

4)

105

08

9=1

1810

-09

P 6

050

1

27(0

78)

6

033

0

98(0

43)

1

05(2

02)

10-0

9 A

11

0

64

247

(17

7)

12

058

1

90(

129

) 1

82(2

52)

1

47(2

20)

1

8211

47=

124

Tab

le 1

0 R

espi

rabl

e D

ust M

ean

and

Geo

met

rc M

ean

by W

orke

r Pa

yne

and

Dol

an

Oct

ober

8 a

nd 9

200

3 G

eom

G

eom

N

umbe

r N

umbe

rM

ean(

SD)

M

ean(

SD)

M

ean

Mea

n U

niJe

tQ 1

1005

GM

Iof

of

Uni

etQ

D

niJe

tQ

(GSD

)

(GSD

)

Uni

etQ

110

08D

ate

Wor

ker

Unigrave

JetQ

U

niJe

tQ

1100

5

1100

8 U

niet

Ol

Unigrave

Jet~

G

Mn0

05

1100

8 11

005

11 0

08

Sam

ples

Sa

mpl

es

10-0

8 Fo

rem

an

3 1

10(0

83)

0

77(3

27)

0

24(1

61)

10

-08

Ope

rato

r 3

026

(01

0)

0

33(2

02)

10

-08

Slaringd

Ste

er

3 0

39(0

25)

2

064

(02

7)

059

(15

3)

061

(15

4)

059

06

1=0

9710

-09

Fore

man

2

062

(02

5)

2 1

38(0

17)

211(11 1)

137

(11

3)

211

13

7=1

5410

-09

2

212

(02

1)O

pera

tor

093

08

5=1

0910

-09

Rea

r C

ontr

ol

2 1

08(0

77)

2

092

(05

1)

093

(22

0)

085

(17

9)

t

Tab

le 1

1 R

espi

rabl

e D

ust M

ean

and

Geo

met

rc M

ean

by L

ocat

ion

Payn

e an

d D

olan

O

ctob

er 8

and

9 2

003

Uni

Jetszlig

U

niet

(szligu

Geo

m M

ean

11 0

05

Mea

n(SD

) 11

008

Mea

n(SD

) Gem Mean

(GSD

)

Uni

etiI

II00

5GM

D

ate

Loc

atio

n N

umbe

r U

niJe

tiI

Num

ber

Uni

Jet(

szlig (G

SD)

U

niet

iI

Uni

JetiI

i 10

08 G

Mof

11

005

of

1100

8 U

niJ

et(szlig

110

05

1100

8Sa

mpl

es

Sam

ples

10

-09

Cut

ter

Dr

Lef

t 2

248

(12

6)

2 2

46(1

25)

2

31(1

70)

2

29(1

71)

2

312

29=

101

10

-09

Rea

r C

ontr

ols

Lef

t 2

400

061

)

2 2

73(0

46)

3

83(1

51)

2

71 (

118

) 3

832

71=

141

10

-09

Ope

rato

r 1

148

0 2

108

(03

9)

lA8(

) 1

04(1

45)

1

481

041

42

10-0

9 C

utte

r D

ru R

ight

2

120

(06

6)

2 0

96(0

28)

1

10(1

79)

0

94(1

35)

1

100

94=

117

10

-09

Upper Conveyor

2 4

47(1

76)

2

372

(07

3)

429

(15

0)

368

(12

2)

429

36

8=1

17

10-0

9 R

ear

Con

trol

s R

ight

2

070

(06

4)

2 0

47(0

14)

0

53(3

03)

0

46(1

36)

0

530

46=

i 1

5

~

Noz

zle

Typ

e Pa

yne

and

Dol

an

Oct

ober

9 2

003

Geo

m M

ean

Geo

m M

ean

Table 12 Respirable Quar Mean by UnietQi

Num

ber

of 1

1005

M

ean

(SD

) N

umbe

r of

110

08

Mea

n (S

D)

1100

5 G

MI

(GSD

) (G

SD)

Sam

ples

1

1005

Sa

mpl

es

1 10

08

1100

8 G

M11

005

1100

8 17

0

13(0

16)

18

0

10(0

094

) 0

078(

269

) 0

067(

264

) 0

780

67=

116

Tab

le 1

3 R

espi

rabl

e Q

uar

Mea

n an

d G

eom

etrc

Mea

n by

Are

a or

Per

sona

l Sam

ple

Payn

e an

d D

olan

O

ctob

er 8

and

92

003

Uni

Jetl

U

niJe

t(I

Geo

m M

ean

Geo

m M

ean

Pers

ona

1100

5 11

008

Mea

n (S

D)

Mea

n (S

D)

(GSD

) D

nigraveJ

etQ

i 1 i

005

GM

(G

SD)

Dat

e or

Are

a N

umbe

r N

umbe

rU

niJe

ti11

005

Uni

JetlI

1100

8 U

niet

i

Uni

JetQ

U

niet

i110

08 G

MSa

mpl

e of

of

11

005

11 0

08

~ Sa

mpl

es

Sam

ples

LUgrave

10

-08

P 9

004

0(0

039)

10

~09

P 6

006

9(0

043)

6

005

4(0

026)

0

057(

202

) 0

048(

181

) 0

057

004

8=1

19

10-0

9 A

11

0

16(0

19)

12

0

13(0

11)

0

092(

303

) 0

080(

299

) 0

092

100

80=

1 1

5

Dat

e W

orke

r

10-0

8 Fo

rem

a 10

-08

Ope

rato

r 10

-08

Skid

Ste

er

10-0

9 Fo

rem

an

10-0

9 O

pera

tor

10-0

9 R

ear

Con

trol

s

~

Tab

le 1

4 R

espIgrave

Tab

le Q

ua M

eans

and

Geo

met

rc M

ean

by W

orke

r

Payn

e an

d D

olan

O

ctob

er 8

and

9 2

003

G

eom

Num

ber

Num

ber

Gom

M

ean

of

Mea

n(SD

) of

M

ean

Mea

n(SD

) (G

SD)

Uni

et(I

U

nigraveet

(szlig

Uni

Jet(

szlig (G

SD)

Uni

Jet(

szlig 11

008

Uiugrave

Jet(

szlig11

005

1100

5 11

008

Unigrave

et(

szlig 1

1008

Sa

mpl

es

Sam

ples

11

005

3 0

072(

005

5)

3 0

046(

403

) 3

001

8(0

0062

) 3

001

7(1

46)

3 0

029(

002

5)

3 0

023(

229

) 2

003

9(0

022)

2

004

1(0

029)

0

035(

182

) 0

036(

218

) 2

012

(00

28)

2 0

080(

000

85)

012

(12

7)

008

0(1

11)

2 0

052(

003

5)

2 0

041(

002

2)

004

6(2

06)

003

8(1

77)

Uni

Jet4

110

05 G

MI

Uni

Jet(

szlig 11

008

GM

003

50

036=

97

012

00

80=

15

004

60

038=

121

Tab

le 1

5 R

espi

rabl

e Q

uar

Mea

n an

d G

eom

etrc

Mea

n by

Loc

atio

n Pa

yne

and

Dol

an

Oct

ober

8 a

nd 9

200

3 U

niet

lszlig

Unicirc

Jetauml

G

eom

Geo

m

1100

5 M

ean(

SD)

1100

8 M

ean(

SD)

M

ean

Mea

n (G

SD

) U

niet

lI 1

1005

GM

I D

ate

Loc

atio

n N

umbe

r U

niet

lI

Num

ber

Unicirc

J et

tj (G

SD)

Uni

JetC

I

Uni

ettj

1100

8 G

Mof

11

005

of

1100

8

Uni

etlI

1

i 005

Sa

mpl

es

Sam

ples

11

008

014

(17

2)

013

01

4=9

310

-09

Cut

ter

Dr

Lef

t 2

014

(00

93)

2 0

15(0

079

)

013

(20

1)

018

(13

1)

018

(1

38)

018

01

8==

1i 0

-09

Rea

r C

ontr

ols

Left

2

018

(00

50)

2 0

19(0

059

) 0

0490

2

003

3(0

028)

0

049

002

6(2

67)

004

90

026=

188

10-0

9 O

pera

tor

1

005

9(2

11)

004

90

059=

083

10-0

9 C

utte

r D

r R

ight

2

005

4(0

034)

2

0

067(

004

6)

004

9(1

94)

029

(00

96)

036

(23

7)

028

(14

1)

036

02

8=1

2910

-09

Upper Conveyor

2 0

43(0

33)

2

002

2(1

85)

002

4(1

97)

002

20

024=

92

i 0-0

9 R

ear

Con

trol

s R

ight

2

0

024

(00

14)

2 0

027(

001

7)

~ (r

Figure 1 Water flow meterS

Figue 2 Cutter drm water supply pressire gauge

27

Figure 3 GPS igravenstniment location

iB

Figure 4 Area sampling array

aq

-- PLAN VIEgraveW

SIDE VIEW

KEY Acirc Machine mounted dust

monitoring locations

3D VIEW I Milling crew dustmonitoring locations

(shown igraven plan view only)

Figure 5 Area Sample Locations

3Otilde

Figure 6 Operator and foreman Foreman is operating right rear controls

31

Figure 7 Position of operator and locatigraveons of personal and area samplers

Tab

le 1

0 R

espi

rabl

e D

ust M

ean

and

Geo

met

rc M

ean

by W

orke

r Pa

yne

and

Dol

an

Oct

ober

8 a

nd 9

200

3 G

eom

G

eom

N

umbe

r N

umbe

rM

ean(

SD)

M

ean(

SD)

M

ean

Mea

n U

niJe

tQ 1

1005

GM

Iof

of

Uni

etQ

D

niJe

tQ

(GSD

)

(GSD

)

Uni

etQ

110

08D

ate

Wor

ker

Unigrave

JetQ

U

niJe

tQ

1100

5

1100

8 U

niet

Ol

Unigrave

Jet~

G

Mn0

05

1100

8 11

005

11 0

08

Sam

ples

Sa

mpl

es

10-0

8 Fo

rem

an

3 1

10(0

83)

0

77(3

27)

0

24(1

61)

10

-08

Ope

rato

r 3

026

(01

0)

0

33(2

02)

10

-08

Slaringd

Ste

er

3 0

39(0

25)

2

064

(02

7)

059

(15

3)

061

(15

4)

059

06

1=0

9710

-09

Fore

man

2

062

(02

5)

2 1

38(0

17)

211(11 1)

137

(11

3)

211

13

7=1

5410

-09

2

212

(02

1)O

pera

tor

093

08

5=1

0910

-09

Rea

r C

ontr

ol

2 1

08(0

77)

2

092

(05

1)

093

(22

0)

085

(17

9)

t

Tab

le 1

1 R

espi

rabl

e D

ust M

ean

and

Geo

met

rc M

ean

by L

ocat

ion

Payn

e an

d D

olan

O

ctob

er 8

and

9 2

003

Uni

Jetszlig

U

niet

(szligu

Geo

m M

ean

11 0

05

Mea

n(SD

) 11

008

Mea

n(SD

) Gem Mean

(GSD

)

Uni

etiI

II00

5GM

D

ate

Loc

atio

n N

umbe

r U

niJe

tiI

Num

ber

Uni

Jet(

szlig (G

SD)

U

niet

iI

Uni

JetiI

i 10

08 G

Mof

11

005

of

1100

8 U

niJ

et(szlig

110

05

1100

8Sa

mpl

es

Sam

ples

10

-09

Cut

ter

Dr

Lef

t 2

248

(12

6)

2 2

46(1

25)

2

31(1

70)

2

29(1

71)

2

312

29=

101

10

-09

Rea

r C

ontr

ols

Lef

t 2

400

061

)

2 2

73(0

46)

3

83(1

51)

2

71 (

118

) 3

832

71=

141

10

-09

Ope

rato

r 1

148

0 2

108

(03

9)

lA8(

) 1

04(1

45)

1

481

041

42

10-0

9 C

utte

r D

ru R

ight

2

120

(06

6)

2 0

96(0

28)

1

10(1

79)

0

94(1

35)

1

100

94=

117

10

-09

Upper Conveyor

2 4

47(1

76)

2

372

(07

3)

429

(15

0)

368

(12

2)

429

36

8=1

17

10-0

9 R

ear

Con

trol

s R

ight

2

070

(06

4)

2 0

47(0

14)

0

53(3

03)

0

46(1

36)

0

530

46=

i 1

5

~

Noz

zle

Typ

e Pa

yne

and

Dol

an

Oct

ober

9 2

003

Geo

m M

ean

Geo

m M

ean

Table 12 Respirable Quar Mean by UnietQi

Num

ber

of 1

1005

M

ean

(SD

) N

umbe

r of

110

08

Mea

n (S

D)

1100

5 G

MI

(GSD

) (G

SD)

Sam

ples

1

1005

Sa

mpl

es

1 10

08

1100

8 G

M11

005

1100

8 17

0

13(0

16)

18

0

10(0

094

) 0

078(

269

) 0

067(

264

) 0

780

67=

116

Tab

le 1

3 R

espi

rabl

e Q

uar

Mea

n an

d G

eom

etrc

Mea

n by

Are

a or

Per

sona

l Sam

ple

Payn

e an

d D

olan

O

ctob

er 8

and

92

003

Uni

Jetl

U

niJe

t(I

Geo

m M

ean

Geo

m M

ean

Pers

ona

1100

5 11

008

Mea

n (S

D)

Mea

n (S

D)

(GSD

) D

nigraveJ

etQ

i 1 i

005

GM

(G

SD)

Dat

e or

Are

a N

umbe

r N

umbe

rU

niJe

ti11

005

Uni

JetlI

1100

8 U

niet

i

Uni

JetQ

U

niet

i110

08 G

MSa

mpl

e of

of

11

005

11 0

08

~ Sa

mpl

es

Sam

ples

LUgrave

10

-08

P 9

004

0(0

039)

10

~09

P 6

006

9(0

043)

6

005

4(0

026)

0

057(

202

) 0

048(

181

) 0

057

004

8=1

19

10-0

9 A

11

0

16(0

19)

12

0

13(0

11)

0

092(

303

) 0

080(

299

) 0

092

100

80=

1 1

5

Dat

e W

orke

r

10-0

8 Fo

rem

a 10

-08

Ope

rato

r 10

-08

Skid

Ste

er

10-0

9 Fo

rem

an

10-0

9 O

pera

tor

10-0

9 R

ear

Con

trol

s

~

Tab

le 1

4 R

espIgrave

Tab

le Q

ua M

eans

and

Geo

met

rc M

ean

by W

orke

r

Payn

e an

d D

olan

O

ctob

er 8

and

9 2

003

G

eom

Num

ber

Num

ber

Gom

M

ean

of

Mea

n(SD

) of

M

ean

Mea

n(SD

) (G

SD)

Uni

et(I

U

nigraveet

(szlig

Uni

Jet(

szlig (G

SD)

Uni

Jet(

szlig 11

008

Uiugrave

Jet(

szlig11

005

1100

5 11

008

Unigrave

et(

szlig 1

1008

Sa

mpl

es

Sam

ples

11

005

3 0

072(

005

5)

3 0

046(

403

) 3

001

8(0

0062

) 3

001

7(1

46)

3 0

029(

002

5)

3 0

023(

229

) 2

003

9(0

022)

2

004

1(0

029)

0

035(

182

) 0

036(

218

) 2

012

(00

28)

2 0

080(

000

85)

012

(12

7)

008

0(1

11)

2 0

052(

003

5)

2 0

041(

002

2)

004

6(2

06)

003

8(1

77)

Uni

Jet4

110

05 G

MI

Uni

Jet(

szlig 11

008

GM

003

50

036=

97

012

00

80=

15

004

60

038=

121

Tab

le 1

5 R

espi

rabl

e Q

uar

Mea

n an

d G

eom

etrc

Mea

n by

Loc

atio

n Pa

yne

and

Dol

an

Oct

ober

8 a

nd 9

200

3 U

niet

lszlig

Unicirc

Jetauml

G

eom

Geo

m

1100

5 M

ean(

SD)

1100

8 M

ean(

SD)

M

ean

Mea

n (G

SD

) U

niet

lI 1

1005

GM

I D

ate

Loc

atio

n N

umbe

r U

niet

lI

Num

ber

Unicirc

J et

tj (G

SD)

Uni

JetC

I

Uni

ettj

1100

8 G

Mof

11

005

of

1100

8

Uni

etlI

1

i 005

Sa

mpl

es

Sam

ples

11

008

014

(17

2)

013

01

4=9

310

-09

Cut

ter

Dr

Lef

t 2

014

(00

93)

2 0

15(0

079

)

013

(20

1)

018

(13

1)

018

(1

38)

018

01

8==

1i 0

-09

Rea

r C

ontr

ols

Left

2

018

(00

50)

2 0

19(0

059

) 0

0490

2

003

3(0

028)

0

049

002

6(2

67)

004

90

026=

188

10-0

9 O

pera

tor

1

005

9(2

11)

004

90

059=

083

10-0

9 C

utte

r D

r R

ight

2

005

4(0

034)

2

0

067(

004

6)

004

9(1

94)

029

(00

96)

036

(23

7)

028

(14

1)

036

02

8=1

2910

-09

Upper Conveyor

2 0

43(0

33)

2

002

2(1

85)

002

4(1

97)

002

20

024=

92

i 0-0

9 R

ear

Con

trol

s R

ight

2

0

024

(00

14)

2 0

027(

001

7)

~ (r

Figure 1 Water flow meterS

Figue 2 Cutter drm water supply pressire gauge

27

Figure 3 GPS igravenstniment location

iB

Figure 4 Area sampling array

aq

-- PLAN VIEgraveW

SIDE VIEW

KEY Acirc Machine mounted dust

monitoring locations

3D VIEW I Milling crew dustmonitoring locations

(shown igraven plan view only)

Figure 5 Area Sample Locations

3Otilde

Figure 6 Operator and foreman Foreman is operating right rear controls

31

Figure 7 Position of operator and locatigraveons of personal and area samplers

Tab

le 1

1 R

espi

rabl

e D

ust M

ean

and

Geo

met

rc M

ean

by L

ocat

ion

Payn

e an

d D

olan

O

ctob

er 8

and

9 2

003

Uni

Jetszlig

U

niet

(szligu

Geo

m M

ean

11 0

05

Mea

n(SD

) 11

008

Mea

n(SD

) Gem Mean

(GSD

)

Uni

etiI

II00

5GM

D

ate

Loc

atio

n N

umbe

r U

niJe

tiI

Num

ber

Uni

Jet(

szlig (G

SD)

U

niet

iI

Uni

JetiI

i 10

08 G

Mof

11

005

of

1100

8 U

niJ

et(szlig

110

05

1100

8Sa

mpl

es

Sam

ples

10

-09

Cut

ter

Dr

Lef

t 2

248

(12

6)

2 2

46(1

25)

2

31(1

70)

2

29(1

71)

2

312

29=

101

10

-09

Rea

r C

ontr

ols

Lef

t 2

400

061

)

2 2

73(0

46)

3

83(1

51)

2

71 (

118

) 3

832

71=

141

10

-09

Ope

rato

r 1

148

0 2

108

(03

9)

lA8(

) 1

04(1

45)

1

481

041

42

10-0

9 C

utte

r D

ru R

ight

2

120

(06

6)

2 0

96(0

28)

1

10(1

79)

0

94(1

35)

1

100

94=

117

10

-09

Upper Conveyor

2 4

47(1

76)

2

372

(07

3)

429

(15

0)

368

(12

2)

429

36

8=1

17

10-0

9 R

ear

Con

trol

s R

ight

2

070

(06

4)

2 0

47(0

14)

0

53(3

03)

0

46(1

36)

0

530

46=

i 1

5

~

Noz

zle

Typ

e Pa

yne

and

Dol

an

Oct

ober

9 2

003

Geo

m M

ean

Geo

m M

ean

Table 12 Respirable Quar Mean by UnietQi

Num

ber

of 1

1005

M

ean

(SD

) N

umbe

r of

110

08

Mea

n (S

D)

1100

5 G

MI

(GSD

) (G

SD)

Sam

ples

1

1005

Sa

mpl

es

1 10

08

1100

8 G

M11

005

1100

8 17

0

13(0

16)

18

0

10(0

094

) 0

078(

269

) 0

067(

264

) 0

780

67=

116

Tab

le 1

3 R

espi

rabl

e Q

uar

Mea

n an

d G

eom

etrc

Mea

n by

Are

a or

Per

sona

l Sam

ple

Payn

e an

d D

olan

O

ctob

er 8

and

92

003

Uni

Jetl

U

niJe

t(I

Geo

m M

ean

Geo

m M

ean

Pers

ona

1100

5 11

008

Mea

n (S

D)

Mea

n (S

D)

(GSD

) D

nigraveJ

etQ

i 1 i

005

GM

(G

SD)

Dat

e or

Are

a N

umbe

r N

umbe

rU

niJe

ti11

005

Uni

JetlI

1100

8 U

niet

i

Uni

JetQ

U

niet

i110

08 G

MSa

mpl

e of

of

11

005

11 0

08

~ Sa

mpl

es

Sam

ples

LUgrave

10

-08

P 9

004

0(0

039)

10

~09

P 6

006

9(0

043)

6

005

4(0

026)

0

057(

202

) 0

048(

181

) 0

057

004

8=1

19

10-0

9 A

11

0

16(0

19)

12

0

13(0

11)

0

092(

303

) 0

080(

299

) 0

092

100

80=

1 1

5

Dat

e W

orke

r

10-0

8 Fo

rem

a 10

-08

Ope

rato

r 10

-08

Skid

Ste

er

10-0

9 Fo

rem

an

10-0

9 O

pera

tor

10-0

9 R

ear

Con

trol

s

~

Tab

le 1

4 R

espIgrave

Tab

le Q

ua M

eans

and

Geo

met

rc M

ean

by W

orke

r

Payn

e an

d D

olan

O

ctob

er 8

and

9 2

003

G

eom

Num

ber

Num

ber

Gom

M

ean

of

Mea

n(SD

) of

M

ean

Mea

n(SD

) (G

SD)

Uni

et(I

U

nigraveet

(szlig

Uni

Jet(

szlig (G

SD)

Uni

Jet(

szlig 11

008

Uiugrave

Jet(

szlig11

005

1100

5 11

008

Unigrave

et(

szlig 1

1008

Sa

mpl

es

Sam

ples

11

005

3 0

072(

005

5)

3 0

046(

403

) 3

001

8(0

0062

) 3

001

7(1

46)

3 0

029(

002

5)

3 0

023(

229

) 2

003

9(0

022)

2

004

1(0

029)

0

035(

182

) 0

036(

218

) 2

012

(00

28)

2 0

080(

000

85)

012

(12

7)

008

0(1

11)

2 0

052(

003

5)

2 0

041(

002

2)

004

6(2

06)

003

8(1

77)

Uni

Jet4

110

05 G

MI

Uni

Jet(

szlig 11

008

GM

003

50

036=

97

012

00

80=

15

004

60

038=

121

Tab

le 1

5 R

espi

rabl

e Q

uar

Mea

n an

d G

eom

etrc

Mea

n by

Loc

atio

n Pa

yne

and

Dol

an

Oct

ober

8 a

nd 9

200

3 U

niet

lszlig

Unicirc

Jetauml

G

eom

Geo

m

1100

5 M

ean(

SD)

1100

8 M

ean(

SD)

M

ean

Mea

n (G

SD

) U

niet

lI 1

1005

GM

I D

ate

Loc

atio

n N

umbe

r U

niet

lI

Num

ber

Unicirc

J et

tj (G

SD)

Uni

JetC

I

Uni

ettj

1100

8 G

Mof

11

005

of

1100

8

Uni

etlI

1

i 005

Sa

mpl

es

Sam

ples

11

008

014

(17

2)

013

01

4=9

310

-09

Cut

ter

Dr

Lef

t 2

014

(00

93)

2 0

15(0

079

)

013

(20

1)

018

(13

1)

018

(1

38)

018

01

8==

1i 0

-09

Rea

r C

ontr

ols

Left

2

018

(00

50)

2 0

19(0

059

) 0

0490

2

003

3(0

028)

0

049

002

6(2

67)

004

90

026=

188

10-0

9 O

pera

tor

1

005

9(2

11)

004

90

059=

083

10-0

9 C

utte

r D

r R

ight

2

005

4(0

034)

2

0

067(

004

6)

004

9(1

94)

029

(00

96)

036

(23

7)

028

(14

1)

036

02

8=1

2910

-09

Upper Conveyor

2 0

43(0

33)

2

002

2(1

85)

002

4(1

97)

002

20

024=

92

i 0-0

9 R

ear

Con

trol

s R

ight

2

0

024

(00

14)

2 0

027(

001

7)

~ (r

Figure 1 Water flow meterS

Figue 2 Cutter drm water supply pressire gauge

27

Figure 3 GPS igravenstniment location

iB

Figure 4 Area sampling array

aq

-- PLAN VIEgraveW

SIDE VIEW

KEY Acirc Machine mounted dust

monitoring locations

3D VIEW I Milling crew dustmonitoring locations

(shown igraven plan view only)

Figure 5 Area Sample Locations

3Otilde

Figure 6 Operator and foreman Foreman is operating right rear controls

31

Figure 7 Position of operator and locatigraveons of personal and area samplers

Noz

zle

Typ

e Pa

yne

and

Dol

an

Oct

ober

9 2

003

Geo

m M

ean

Geo

m M

ean

Table 12 Respirable Quar Mean by UnietQi

Num

ber

of 1

1005

M

ean

(SD

) N

umbe

r of

110

08

Mea

n (S

D)

1100

5 G

MI

(GSD

) (G

SD)

Sam

ples

1

1005

Sa

mpl

es

1 10

08

1100

8 G

M11

005

1100

8 17

0

13(0

16)

18

0

10(0

094

) 0

078(

269

) 0

067(

264

) 0

780

67=

116

Tab

le 1

3 R

espi

rabl

e Q

uar

Mea

n an

d G

eom

etrc

Mea

n by

Are

a or

Per

sona

l Sam

ple

Payn

e an

d D

olan

O

ctob

er 8

and

92

003

Uni

Jetl

U

niJe

t(I

Geo

m M

ean

Geo

m M

ean

Pers

ona

1100

5 11

008

Mea

n (S

D)

Mea

n (S

D)

(GSD

) D

nigraveJ

etQ

i 1 i

005

GM

(G

SD)

Dat

e or

Are

a N

umbe

r N

umbe

rU

niJe

ti11

005

Uni

JetlI

1100

8 U

niet

i

Uni

JetQ

U

niet

i110

08 G

MSa

mpl

e of

of

11

005

11 0

08

~ Sa

mpl

es

Sam

ples

LUgrave

10

-08

P 9

004

0(0

039)

10

~09

P 6

006

9(0

043)

6

005

4(0

026)

0

057(

202

) 0

048(

181

) 0

057

004

8=1

19

10-0

9 A

11

0

16(0

19)

12

0

13(0

11)

0

092(

303

) 0

080(

299

) 0

092

100

80=

1 1

5

Dat

e W

orke

r

10-0

8 Fo

rem

a 10

-08

Ope

rato

r 10

-08

Skid

Ste

er

10-0

9 Fo

rem

an

10-0

9 O

pera

tor

10-0

9 R

ear

Con

trol

s

~

Tab

le 1

4 R

espIgrave

Tab

le Q

ua M

eans

and

Geo

met

rc M

ean

by W

orke

r

Payn

e an

d D

olan

O

ctob

er 8

and

9 2

003

G

eom

Num

ber

Num

ber

Gom

M

ean

of

Mea

n(SD

) of

M

ean

Mea

n(SD

) (G

SD)

Uni

et(I

U

nigraveet

(szlig

Uni

Jet(

szlig (G

SD)

Uni

Jet(

szlig 11

008

Uiugrave

Jet(

szlig11

005

1100

5 11

008

Unigrave

et(

szlig 1

1008

Sa

mpl

es

Sam

ples

11

005

3 0

072(

005

5)

3 0

046(

403

) 3

001

8(0

0062

) 3

001

7(1

46)

3 0

029(

002

5)

3 0

023(

229

) 2

003

9(0

022)

2

004

1(0

029)

0

035(

182

) 0

036(

218

) 2

012

(00

28)

2 0

080(

000

85)

012

(12

7)

008

0(1

11)

2 0

052(

003

5)

2 0

041(

002

2)

004

6(2

06)

003

8(1

77)

Uni

Jet4

110

05 G

MI

Uni

Jet(

szlig 11

008

GM

003

50

036=

97

012

00

80=

15

004

60

038=

121

Tab

le 1

5 R

espi

rabl

e Q

uar

Mea

n an

d G

eom

etrc

Mea

n by

Loc

atio

n Pa

yne

and

Dol

an

Oct

ober

8 a

nd 9

200

3 U

niet

lszlig

Unicirc

Jetauml

G

eom

Geo

m

1100

5 M

ean(

SD)

1100

8 M

ean(

SD)

M

ean

Mea

n (G

SD

) U

niet

lI 1

1005

GM

I D

ate

Loc

atio

n N

umbe

r U

niet

lI

Num

ber

Unicirc

J et

tj (G

SD)

Uni

JetC

I

Uni

ettj

1100

8 G

Mof

11

005

of

1100

8

Uni

etlI

1

i 005

Sa

mpl

es

Sam

ples

11

008

014

(17

2)

013

01

4=9

310

-09

Cut

ter

Dr

Lef

t 2

014

(00

93)

2 0

15(0

079

)

013

(20

1)

018

(13

1)

018

(1

38)

018

01

8==

1i 0

-09

Rea

r C

ontr

ols

Left

2

018

(00

50)

2 0

19(0

059

) 0

0490

2

003

3(0

028)

0

049

002

6(2

67)

004

90

026=

188

10-0

9 O

pera

tor

1

005

9(2

11)

004

90

059=

083

10-0

9 C

utte

r D

r R

ight

2

005

4(0

034)

2

0

067(

004

6)

004

9(1

94)

029

(00

96)

036

(23

7)

028

(14

1)

036

02

8=1

2910

-09

Upper Conveyor

2 0

43(0

33)

2

002

2(1

85)

002

4(1

97)

002

20

024=

92

i 0-0

9 R

ear

Con

trol

s R

ight

2

0

024

(00

14)

2 0

027(

001

7)

~ (r

Figure 1 Water flow meterS

Figue 2 Cutter drm water supply pressire gauge

27

Figure 3 GPS igravenstniment location

iB

Figure 4 Area sampling array

aq

-- PLAN VIEgraveW

SIDE VIEW

KEY Acirc Machine mounted dust

monitoring locations

3D VIEW I Milling crew dustmonitoring locations

(shown igraven plan view only)

Figure 5 Area Sample Locations

3Otilde

Figure 6 Operator and foreman Foreman is operating right rear controls

31

Figure 7 Position of operator and locatigraveons of personal and area samplers

Dat

e W

orke

r

10-0

8 Fo

rem

a 10

-08

Ope

rato

r 10

-08

Skid

Ste

er

10-0

9 Fo

rem

an

10-0

9 O

pera

tor

10-0

9 R

ear

Con

trol

s

~

Tab

le 1

4 R

espIgrave

Tab

le Q

ua M

eans

and

Geo

met

rc M

ean

by W

orke

r

Payn

e an

d D

olan

O

ctob

er 8

and

9 2

003

G

eom

Num

ber

Num

ber

Gom

M

ean

of

Mea

n(SD

) of

M

ean

Mea

n(SD

) (G

SD)

Uni

et(I

U

nigraveet

(szlig

Uni

Jet(

szlig (G

SD)

Uni

Jet(

szlig 11

008

Uiugrave

Jet(

szlig11

005

1100

5 11

008

Unigrave

et(

szlig 1

1008

Sa

mpl

es

Sam

ples

11

005

3 0

072(

005

5)

3 0

046(

403

) 3

001

8(0

0062

) 3

001

7(1

46)

3 0

029(

002

5)

3 0

023(

229

) 2

003

9(0

022)

2

004

1(0

029)

0

035(

182

) 0

036(

218

) 2

012

(00

28)

2 0

080(

000

85)

012

(12

7)

008

0(1

11)

2 0

052(

003

5)

2 0

041(

002

2)

004

6(2

06)

003

8(1

77)

Uni

Jet4

110

05 G

MI

Uni

Jet(

szlig 11

008

GM

003

50

036=

97

012

00

80=

15

004

60

038=

121

Tab

le 1

5 R

espi

rabl

e Q

uar

Mea

n an

d G

eom

etrc

Mea

n by

Loc

atio

n Pa

yne

and

Dol

an

Oct

ober

8 a

nd 9

200

3 U

niet

lszlig

Unicirc

Jetauml

G

eom

Geo

m

1100

5 M

ean(

SD)

1100

8 M

ean(

SD)

M

ean

Mea

n (G

SD

) U

niet

lI 1

1005

GM

I D

ate

Loc

atio

n N

umbe

r U

niet

lI

Num

ber

Unicirc

J et

tj (G

SD)

Uni

JetC

I

Uni

ettj

1100

8 G

Mof

11

005

of

1100

8

Uni

etlI

1

i 005

Sa

mpl

es

Sam

ples

11

008

014

(17

2)

013

01

4=9

310

-09

Cut

ter

Dr

Lef

t 2

014

(00

93)

2 0

15(0

079

)

013

(20

1)

018

(13

1)

018

(1

38)

018

01

8==

1i 0

-09

Rea

r C

ontr

ols

Left

2

018

(00

50)

2 0

19(0

059

) 0

0490

2

003

3(0

028)

0

049

002

6(2

67)

004

90

026=

188

10-0

9 O

pera

tor

1

005

9(2

11)

004

90

059=

083

10-0

9 C

utte

r D

r R

ight

2

005

4(0

034)

2

0

067(

004

6)

004

9(1

94)

029

(00

96)

036

(23

7)

028

(14

1)

036

02

8=1

2910

-09

Upper Conveyor

2 0

43(0

33)

2

002

2(1

85)

002

4(1

97)

002

20

024=

92

i 0-0

9 R

ear

Con

trol

s R

ight

2

0

024

(00

14)

2 0

027(

001

7)

~ (r

Figure 1 Water flow meterS

Figue 2 Cutter drm water supply pressire gauge

27

Figure 3 GPS igravenstniment location

iB

Figure 4 Area sampling array

aq

-- PLAN VIEgraveW

SIDE VIEW

KEY Acirc Machine mounted dust

monitoring locations

3D VIEW I Milling crew dustmonitoring locations

(shown igraven plan view only)

Figure 5 Area Sample Locations

3Otilde

Figure 6 Operator and foreman Foreman is operating right rear controls

31

Figure 7 Position of operator and locatigraveons of personal and area samplers

Tab

le 1

5 R

espi

rabl

e Q

uar

Mea

n an

d G

eom

etrc

Mea

n by

Loc

atio

n Pa

yne

and

Dol

an

Oct

ober

8 a

nd 9

200

3 U

niet

lszlig

Unicirc

Jetauml

G

eom

Geo

m

1100

5 M

ean(

SD)

1100

8 M

ean(

SD)

M

ean

Mea

n (G

SD

) U

niet

lI 1

1005

GM

I D

ate

Loc

atio

n N

umbe

r U

niet

lI

Num

ber

Unicirc

J et

tj (G

SD)

Uni

JetC

I

Uni

ettj

1100

8 G

Mof

11

005

of

1100

8

Uni

etlI

1

i 005

Sa

mpl

es

Sam

ples

11

008

014

(17

2)

013

01

4=9

310

-09

Cut

ter

Dr

Lef

t 2

014

(00

93)

2 0

15(0

079

)

013

(20

1)

018

(13

1)

018

(1

38)

018

01

8==

1i 0

-09

Rea

r C

ontr

ols

Left

2

018

(00

50)

2 0

19(0

059

) 0

0490

2

003

3(0

028)

0

049

002

6(2

67)

004

90

026=

188

10-0

9 O

pera

tor

1

005

9(2

11)

004

90

059=

083

10-0

9 C

utte

r D

r R

ight

2

005

4(0

034)

2

0

067(

004

6)

004

9(1

94)

029

(00

96)

036

(23

7)

028

(14

1)

036

02

8=1

2910

-09

Upper Conveyor

2 0

43(0

33)

2

002

2(1

85)

002

4(1

97)

002

20

024=

92

i 0-0

9 R

ear

Con

trol

s R

ight

2

0

024

(00

14)

2 0

027(

001

7)

~ (r

Figure 1 Water flow meterS

Figue 2 Cutter drm water supply pressire gauge

27

Figure 3 GPS igravenstniment location

iB

Figure 4 Area sampling array

aq

-- PLAN VIEgraveW

SIDE VIEW

KEY Acirc Machine mounted dust

monitoring locations

3D VIEW I Milling crew dustmonitoring locations

(shown igraven plan view only)

Figure 5 Area Sample Locations

3Otilde

Figure 6 Operator and foreman Foreman is operating right rear controls

31

Figure 7 Position of operator and locatigraveons of personal and area samplers

Figure 1 Water flow meterS

Figue 2 Cutter drm water supply pressire gauge

27

Figure 3 GPS igravenstniment location

iB

Figure 4 Area sampling array

aq

-- PLAN VIEgraveW

SIDE VIEW

KEY Acirc Machine mounted dust

monitoring locations

3D VIEW I Milling crew dustmonitoring locations

(shown igraven plan view only)

Figure 5 Area Sample Locations

3Otilde

Figure 6 Operator and foreman Foreman is operating right rear controls

31

Figure 7 Position of operator and locatigraveons of personal and area samplers

Figue 2 Cutter drm water supply pressire gauge

27

Figure 3 GPS igravenstniment location

iB

Figure 4 Area sampling array

aq

-- PLAN VIEgraveW

SIDE VIEW

KEY Acirc Machine mounted dust

monitoring locations

3D VIEW I Milling crew dustmonitoring locations

(shown igraven plan view only)

Figure 5 Area Sample Locations

3Otilde

Figure 6 Operator and foreman Foreman is operating right rear controls

31

Figure 7 Position of operator and locatigraveons of personal and area samplers

Figure 3 GPS igravenstniment location

iB

Figure 4 Area sampling array

aq

-- PLAN VIEgraveW

SIDE VIEW

KEY Acirc Machine mounted dust

monitoring locations

3D VIEW I Milling crew dustmonitoring locations

(shown igraven plan view only)

Figure 5 Area Sample Locations

3Otilde

Figure 6 Operator and foreman Foreman is operating right rear controls

31

Figure 7 Position of operator and locatigraveons of personal and area samplers

Figure 4 Area sampling array

aq

-- PLAN VIEgraveW

SIDE VIEW

KEY Acirc Machine mounted dust

monitoring locations

3D VIEW I Milling crew dustmonitoring locations

(shown igraven plan view only)

Figure 5 Area Sample Locations

3Otilde

Figure 6 Operator and foreman Foreman is operating right rear controls

31

Figure 7 Position of operator and locatigraveons of personal and area samplers

-- PLAN VIEgraveW

SIDE VIEW

KEY Acirc Machine mounted dust

monitoring locations

3D VIEW I Milling crew dustmonitoring locations

(shown igraven plan view only)

Figure 5 Area Sample Locations

3Otilde

Figure 6 Operator and foreman Foreman is operating right rear controls

31

Figure 7 Position of operator and locatigraveons of personal and area samplers

Figure 6 Operator and foreman Foreman is operating right rear controls

31

Figure 7 Position of operator and locatigraveons of personal and area samplers

Figure 7 Position of operator and locatigraveons of personal and area samplers