Port Washington Road Relief Sewer Vol III

8/9/2019 Port Washington Road Relief Sewer Vol III

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PORT WASHINGTON ROAD RELIEF SEWER

PRELIMINARY ENGINEERING REPORT

Volume 3

Prepared for:

Milwaukee Metropolitan

Sewerage District

MMSD Project: CO5013E01

Prepared by:

in association with

September 2006


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PRELIMINARY ENGINEERING REPORT

Volume 3

Prepared for:

Milwaukee Metropolitan Sewerage District

MMSD Contract No. CO5013E01

Prepared by:

Brown and Caldwell

in association with

HNTB Corporation

September 2006


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PRELIMINARY GEOTECHNICAL DATA

REPORT

Prepared for:

Milwaukee Metropolitan Sewerage District

MMSD Contract No. CO5013E01

Prepared by:

Brown and Caldwell

in association with

HNTB Corporation

R.I. Geotechnical, Inc.

November 2005


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CONTENTS

PROJECT OVERVIEW ...................................................................................................1

Introduction.......................................................................................................................1

Purpose and Scope of Preliminary Geotechnical Data Report .........................................1

HISTORICAL SUBSURFACE INFORMATION...........................................................1

Summary of Historical Subsurface Information Reviewed ..............................................1

Published Literature and Theses.......................................................................................2

As-Built Records of MMSD Tunnel Construction...........................................................2

EXPLORATION AND TESTING PROCEDURES........................................................2

Boring Location and Survey .............................................................................................2

Drilling and Sampling Procedures....................................................................................3Groundwater Measurement and Borehole Abandonment.................................................4Field and Laboratory Testing Programs ...........................................................................4

PRELIMINARY SITE GEOLOGY EVALUATIONS....................................................5

Exploration Plan................................................................................................................5

Soil Conditions..................................................................................................................5Rock Conditions................................................................................................................5

Bedrock Topography ............................................................................................5

Rock Formations Present ......................................................................................5

Thiensville Formation...........................................................................................6Waubakee Formation............................................................................................6

Racine Formation..................................................................................................6

Waukesha Formation ............................................................................................7Bedrock Structure .................................................................................................7

Indications of Faulting from the Study.................................................................8Groundwater .....................................................................................................................9

Water Wells ..........................................................................................................9

Bedrock Groundwater...........................................................................................9

REFERENCES ...............................................................................................................11

APPENDICES

Appendix A Summary of Review of Geotechnical Reports and As-Builts from MMSD

Projects in the Study Area

Appendix B Boring Logs with General Notes

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Appendix C Completed Monitoring Well Construction Forms and Borehole

Abandonment Forms

Appendix D Water Pressure Tests Results

Appendix E Laboratory Tests on Soil Samples

Appendix F Laboratory Tests on Rock Samples

TABLES

1 Summary of Boring and Elevations

2 Summary of Piezometric and Standing Water Elevations

3 Thicknesses of Soil and Rock Formations at Boring Locations

4 Ranges of Core Recovery and Rock Quality Designation

FIGURES

1 Milwaukee River Alignment: Boring Locations

2 27th Street Alignment: Boring Locations

3 Milwaukee River Alignment: Geologic Profile

4 27th

Street Alignment: Geologic Profile

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North Side High Level Relief Sewer, MMSD Contract Nos. I48G11, G12, G13, G14,G15 and As-Builts [3]

Northeast Side Relief Sewer System East Branch, Contracts 287 and 288. MMSDContract No. I45541 and As-Builts for Contract 287 only. [4]

North Shore Interceptor Phase IIA Lining Report No. 2. [5] Rust/Harza, 2002, Estabrook Parkway and Glendale Avenue Relief Project, DesignContract CO48DE001 Alternative Analysis [6] Published literature on local geology and soil properties [7, 10, 11] Records of residential and high capacity city wells from the City of Glendale Geologic maps of the North Shore Interceptor, Phase II tunnelPublished Literature and ThesesThe referenced sources include discussions of area glacial and post-glacial soils and rock

geology. Several publications describe the Quaternery soil deposits of the area and

provide generalized discussions of soil composition. Reference 7 was authored by

former Milwaukee Water Pollution Abatement Program (MWPAP) staff and presents a

summary of geotechnical properties of the soils in the Milwaukee area. The paper wasbased on information from the MWPAP exploration borings and laboratory testing data

in the period 1980 to 1983. The paper provides geologic characteristics for the primary

soil units identified and summarizes their index and engineering properties. Reference 10

provides discussions of rock stratigraphy in the area. Reference 11 describes solutionfeatures encountered in the North Shore Tunnel and their impacts on mining.

As-Built Records of MMSD Tunnel ConstructionThese records include geologic tunnel maps and as-built profiles recording the geologyencountered, methods of construction and daily progress rates. A summary is provided in

Appendix A.

EXPLORATION AND TESTING PROCEDURES

Boring Location and SurveyFive new borings were completed during the latter half of 2004. Figures 1 and 2 show

the boring locations on the Milwaukee River and 27th

Street Alignments, respectively:three are located on the Milwaukee River Alignment and two are on the 27 th Street

Alignment. All of the borings were originally spaced along the Milwaukee River

Alignment to allow development of the preliminary alignment stratigraphy and to

investigate ground conditions at the probable shaft locations. Subsequently, the 27th

Street Alignment was recognized as a potential alternative and the budgeted borings werethen split between the two alignments. The resultant spacing is relatively wide, but does

allow preliminary stratigraphic evaluations when combined with data from the NorthShore Phase II geotechnical report and provides information at probable shaft sites.

The borings were surveyed to determine state plane coordinates and ground surfaceelevations. These data are shown on the boring logs and in Table 1. Elevations are

reported in terms of the MMSD datum, which is the same as Milwaukee City datum.

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Table 1

Summary of Boring Elevations

Preliminary Geotechnical Investigation

Port Washington Road Relief Sewer

Notes: ---- No piezometer installed

----

Surface

Elevation (Feet,

MMSD Datum)

Top of Piezometer

Casing Elevation

(Feet, MMSD

Datum)

46.72

Boring No.

95.37

----

----

CA-3

46.88

95.66

48.55

47.38

58.48

WA-1

WA-2B

CA-1

CA-2


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Note that elevation 0.0 feet MMSD datum equals 580.6 feet National Vertical GeodeticDatum (NVGD).

Drilling and Sampling ProceduresThe borings were conducted in accordance with the Field Manual for Subsurface

Exploration [8].

Terracon, Inc. using a CME-750 rubber-tired, all-terrain drill rig, completed the borings.

Drilling inspection and initial soil classification was done principally by a technician,

assisted by a geologist, both of HNTB.

The borings at shaft locations (WA-2, WA-2, CA-3) were sampled at 5-foot intervals in

the soil. Piezometers were also established in the rock at these locations. The rock wascored using double-tube HQ wireline equipment and water return in general accordance

with ASTM D2113, Standard Practice for Diamond Core Drilling and Site Investigation.

The core was removed from the core barrel and laid out in a trough. The field technicianthen measured the core and established core recovery and Rock Quality Designation

(RQD), which he then recorded on the inside lid of the core box. The core was also

photographed in the core box before daily transfer to the MMSD core storage and loggingfacility. A geologist subsequently logged the cores. The logging included a detailed

lithologic description of the core and descriptions of significant discontinuities, such as

faults, bedding and joints. Mechanical breaks were identified and the RQD adjustedaccordingly. After the draft logs were produced, a senior geologist checked the lithologic

descriptions and formation boundaries.

Soil samples were obtained using a split-barrel sampler driven according to ASTM

D1586 Standard Method for Penetration Test and Split-Barrel Sampling of Soils.

The soil samples were placed in appropriately labeled seal top glass jars and transportedto the MMSD storage facility. Subsequently, a geotechnical engineer checked the soil

classifications made by the field technician.

All of the rock portions of the borings were water pressure tested using four pressure

increments: 25 psi, 50 psi, 75 psi, 25 psi again. The double packer pressure tests were

conducted for 20-foot depth increments from the bottom of the borehole upwards.

The field technician observed the drilling and completed the appropriate field logs for

both rock and soil. He also recorded the data from the water pressure testing conductedin the rock, the details of the piezometer, placement and recorded standing water levels inthe boreholes and piezometers.

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Groundwater Measurement and Borehole AbandonmentDuring drilling, the field technician noted the presence of inflows, or wet conditions, in

the boreholes while drilling and sampling in the soil and loss or gain of drill water returnwhile in the rock. Standing water levels were recorded in the boreholes when possible.

Piezometers were constructed in boreholes WA-1 and WA-2 to sense the piezometriclevel within the rock. The levels recorded are noted on the borehole logs and presentedin Table 2. Copies of completed Monitoring Well Construction Forms, as required by the

Wisconsin Department of Natural Resources (WDNR), are included in Appendix C.

Piezometric water levels should be recorded periodically in the final design phase and thepiezometers specified for abandonment under the construction contract after use in the

construction phase.

The drilling crew backfilled and abandoned the remaining boreholes in accordance with

WDNR regulations. Because of artesian conditions in boring CA-2 (water level

approximately 11 feet above the ground surface), an inflatable packer was inserted in the

rock to cut-off the upward flow and allow grouting of the borehole. Copies of thecompleted borehole abandonment forms are included in Appendix C.

Field and Laboratory Testing ProgramsWater pressure (packer) testing of all of the rock portions of the boreholes was completed

except for boring CA-1 where the core barrel became stuck in the upper part of the

borehole and in the ensuing over-drilling, the hole was enlarged such that the packerswould not fit.

The packer test set-up consisted of two inflatable packers enclosing a 20-foot piece ofperforated steel pipe through which water was introduced from the surface under

pressure. The test zone was tested at gauge pressures of 25, 50, 75 and subsequently 25psi. Using these data, the permeability (hydraulic conductivity) was calculated for eachpressure increment and reported in cm/sec. Using the approach suggested by Houlsby [9]

which compares the trend of volume of water take for each pressure increment, a

representative value of permeability was selected and recorded on the boring logs. Thepressure test data and the values of permeability calculated are presented in Appendix D.

The field technician visually examined in the field the recovered Standard Penetration

Test (SPT) samples to initially classify the samples in accordance with the Unified SoilClassification System (USCS) as described in the HNTB Field Manual. After

examination, the soils were placed in glass jars with moisture-proof lids and labeled. The

sample jars were transported to the MMSD storage facility where a geotechnical engineerexamined them, the soil classifications were verified and laboratory test samples selected

for testing. The soil testing was done by Terracon and consisted of moisture contents,

unconfined compression, Atterberg Limit tests and unit weight measurement on thecohesive soil samples. Grain size analysis tests were done on selected granular soil

samples. The results of some of the soil test results are shown on the logs. All of the soil

test results are presented in Appendix E.

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10/7/2004 10/15/2004 12/15/2004

Notes: Elevations are feet, MMSD datum

Top of casing elevation WA-1: 46.72

Top of casing elevation WA-2B: 95.37

Ground elevation CA-1: 48.55

Ground elevation CA-3: 58.48

Flowing artesian conditions present at borehole CA-2

---- Not Applicable

65.77

----

47.18

70.82

-10.95

----

WA-2B Piezometer

Groundwater ElevationCA-1 Open Borehole

Groundwater ElevationCA-3 Open Borehole

Groundwater Elevation

----

----

----

Date

Boring/Piezometer No.WA-1 Piezometer

Groundwater Elevation-42.53 -41.78 -42.30

Table 2

Summary of Piezometric and Standing Water Elevations




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The senior geologist selected rock core samples for testing. The laboratory testing wasdone by Geotest and consisted of unconfined compression tests with elastic modulus

measurement; indirect tensile strength measurement (Brazilian Disc) and bulk density

measurement. The results are presented in Appendix F and on the boring logs.

PRELIMINARY SITE GEOLOGY EVALUATIONS

Exploration PlanThe initially conceived exploration plan focused on the Milwaukee River Alignment.After review of existing geologic data and the results of flow tests in existing facilities, it

was decided to explore the 27th Street alignment as well. Hence, the originally planned

borings were spread over two alignments, two on the 27 th Street Alignment and three on

the Milwaukee River Alignment. The rationale was that this exploration data, coupledwith existing geologic data, would be sufficient to characterize the alignment for the

purpose of confirmation of the general stratigraphy, ground water conditions, soil

conditions and top of rock at potential shaft sites. Once a preferred alignment has been

selected and the required tunnel storage capacity decided upon, additional borings may bedrilled during this preliminary phase.

Soil ConditionsThe characteristics of the soils along the two alignments are most important at the

potential shaft sites. Therefore, soil sampling was only conducted at these sites in

borings WA-1, WA-2 and CA-3. This report does not provide detailed soil descriptionsat these shaft locations because they are preliminary.

The thickness of soil at boreholes WA-1, WA-2 and CA-3 was 124.0, 59.4 and 46.5 feet.Appendix A provides a compilation of soil and rock tunneling experience and geologic

conditions in the project area.

Rock Conditions

Bedrock Topography

The bedrock topography in the study area is formed by the Milwaukee, Thiensville,Waubakee and Racine Formations [Refer to Figure 4, Appendix A]. Tunneling

experience has shown that where Devonian Age rocks form the top of rock, topographical

relief of tens of feet over plan distances of 100 feet of the bedrock surface is common.There are indications of a bedrock valley broadly extending from 27 th Street and Villard

Avenue to the east northeast, encompassing borings WA-1, CA-1 and CA-2. This

bedrock valley is likely fault controlled and will be discussed further below.

Rock Formations Present

In descending depth from the ground surface, the rock formations present in the projectarea are the Milwaukee, Thiensville, Waubakee, Racine, Waukesha and Mayville

Formations. Detailed descriptions of these formations from previous MMSD project siteinvestigations are presented in Appendix A.

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The five borings drilled during this exploration phase [see Appendix B for boring logs]on the Milwaukee River and 27th Street Alignments all penetrated to approximately 20

feet below the proposed tunnel inverts (refer to Figures 3 and 4) respectively. The

thickness of the soil and rock formations encountered is presented in Table 3. Note thatthe Milwaukee Formation was not present at any of the boring locations and that soil

depths ranging from 124 to 144.5 feet thick at borings WA-1, CA-1 and CA-2 indicate abedrock valley trending east northeast across the project area. The lithology of the rockformations encountered is described on the boring logs and conforms generally to that

previously encountered in prior MMSD exploration borings [Appendix A].

Thiensville Formation

The Thiensville Formation formed the top of rock at boreholes WA-2 and CA-3 at the

north end of each alignment. These are the probable locations of workshafts and/or

dropshafts. The formation consists of solutioned limestones with very soft to moderatelyhard mudstone, siltstone and calcareous sandstone interbeds, the whole being moderately

to severely weathered. Refer to Table 4 for the ranges of core recovery, defined as the

percentage of core recovered from a given core run length. Also, the Rock QualityDesignation (RQD), defined as the percentage of total length of pieces of core greater

than four inches in length in a given core run length.

The contact between the Thiensville Formation and the underlying Waubakee Formationis an unconformity. A relief of eight feet in 500 feet was recorded on this unconformity in

an 8-foot diameter rock tunnel further west on N. 43 rd Street.

Waubakee Formation

The Waubakee Formation was encountered in borings WA-2, CA-1, CA-2 and CA-3

with thickness ranging from 43.2 to 89.7 feet and formed the top of rock at borings CA-1

and CA-2. The formation generally consists of very thin to thinly bedded dolomite withthin, alternating brown and light and dark gray bands. The typical bedding plane parting

is very thin shale across which the core readily separates, giving a smooth planar surface.

In borehole CA-1, bedding dips of 10 to 12 degrees, very frequently with clay infill, werenoted. The bedding dip is likely due to the presence of a nearby reef in the Racine

Formation over which the Waubakee beds have draped, creating inclined flank beds.

Refer to Table 4 for ranges of core recovery and RQD. The RQD was likely reduced

when the core was removed from the barrel because of its propensity to part readily aspreviously described.

Racine Formation

The Racine Formation was encountered in all five borings in thicknesses ranging from

75.8 to 187.4 feet and forms the top of rock at boring WA-1. The formation generally

consists of fine-grained, thin to medium bedded dolomite with argillaceous partings onbedding planes, stylolite zones and is slightly to moderately weathered.

An artesian flow condition was intercepted in this formation during the drilling of runnumber 27 [depth increment 227.5 to 236 feet] in borehole CA-2. The head above the

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WA-1 WA-2B CA-1 CA-2 CA-3

Soil 126.5 59.4 130.5 144.5 46.5

Total Depth (Feet) 300.5 339.0 296.3 302.0 294.0

Notes: ---- Formation not encountered

---- ----

126.2

47.8 16.7 ----

113.5114.376.1178.1

---- 67.3

66.743.2----

---- 29.1 ----

89.755.7

Thiensville

Formation

Waubakee

Formation

Racine Formation

Waukesha

Formation

Thickness of Soil and Rock Formations at Boring Locations

Table 3

Boring No.



Thickness (feet)


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Thiensville Waubakee Racine

Rec % RQD % Rec % RQD % Rec % RQD %

Notes: ---- Formation not encountered

NA Not Applicable

Rec % Recovery (Percent)

RQD % Rock Quality Designation (Percent)

94-100

74-100

85-100

87-100

98-100

97-100

97-100

97-100

76-95

43-70

37-100

35-96

94-100

98-100

80-100

98-10021-100

----

----

0-52

71-100 36-71

----

----

95-100 92-100---- ---- ---- ----

Boring No.

Table 4

Ranges of Core Recovery and Rock Quality Designation



CA-2

CA-3

WA-1

WA-2B

CA-1


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ground surface was measured at 11 feet and an initial flow of about 60 gpm declining to30 gpm. A small breccia zone, solutioned joints and a core loss of approximately four

inches were noted in the core for run number 27. A subsequent water pressure (double

packer) test gave a permeability value of 3.1 x 102

cm/sec for the depth increment of 229to 249 feet. Very high permeabilities of 3.4 to 3.6 x 10-2 cm/sec were recorded in this

formation in borehole CA-3 in the depth increment of 40 feet between 197 and 237 feet.The core log notes a small void and vuggy and broken rock which are indications ofsolutioning. Refer to Table 4 for ranges in core recovery and RQD.

Waukesha Formation

Because the planned tunnel will intersect with the existing North Shore Phase II Tunnel,the geologic information from borings and geologic tunnel maps will be used for the rock

mass characterization in this study. To facilitate the use of this information, it was

decided to conform to the same criteria used for selecting the boundary between theRacine and Waukesha Formations; the principal criterion being the first appearance of

chert.

The Waukesha Formation was encountered in borings WA-1 and WA-2 with partial

thicknesses (bottom of formation not encountered) of 39.7 and 6.6 feet respectively. The

formation generally consists of thinly bedded, fresh to slightly weathered dolomite, with

frequent chert nodules and few stylolites. Refer to Table 4 for the range of core recoveryand RQD.

Bedrock Structure

Relevant generalized descriptions of the rock structure at the proposed tunnel depth are

presented in the Geotechnical Report for the North Shore Phase II Tunnel [1] and LiningReport No. 2 [5] for this tunnel. Sections from this report discussing pertinent aspects of

the geology, water inflow and construction experience are presented in Appendix A.

Because joint spacing orientation and their detailed characteristics are more readilyobtained during tunnel mapping than from vertical borings, these parameters will be

reproduced here from Lining Report No. 2.

The majority of faults and joints observed in the North Shore Phase II Tunnel

belong to two joint sets. Based on the geological mapping of the entire tunnel,

the mean orientation of the two sets are: strike N47 W, dip 89 NE; and strike

N41 E, dip 89 NW.

True joint spacings (measured perpendicular to joint strike) are shown below:

Joint SetMinimum

(ft)

Maximum

(ft)

Median

(ft)

No. of Joints

(ft)

NW


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Joint Filling

CharacteristicsClay Shale Silt Mineralized Unfilled

Mean Width

(ft)0.13 0.02 0.06 0.04 0.01

NE Occurrence

(%)

16 18 14 7 30

More than one-third of the discontinuities are mapped as faults. The sole

geologic criterion used to identify features as faults is evidence of

displacement of the 162 faults; about three-quarters of them have widths of

less than 0.1 foot. Sixteen of the faults have widths 0.1 to 0.5 foot and 26 of

the faults have widths greater than 0.5 foot. A shear zone located at station

361+65 has a width of about 10 feet. Most of the observed faults have

apparent vertical displacement less than one foot. Less than 10% of the faults

have displacements greater than one foot, with the maximum displacement

being about 15 feet.

In regard to bedding planes, it says,

Solutioned bedding planes within the Racine Formation occurs at a much

greater frequency than anticipated in the Geotechnical Report. For example,

a single bedding plane was intersected between about Station 329 and

306+00. Along much of its length solutioning had widened the bedding plane

to 1-2 feet. Portions of the bedding plane were filled with red claystone.

Other portions were open and produced significant amounts of groundwater

infiltration to the tunnel during and after mining.

Indication of Faults from this Study

The regional dip of the rock formations is about 1 degree (about 90 feet/mile) to the eastand is illustrated on Figure 5, Appendix A. Therefore, it is generally expected that ageologic section perpendicular to the dip along the strike will show formation boundaries

which are close to horizontal. This is shown on Figure 7, Appendix A which is an as-

built geologic profile in a North-South direction along the strike from station 410+00 toabout station 453+50 of the North Shore Phase IIA Tunnel. The boundary between the

Waukesha and Mayville Formations is sub-horizontal to horizontal and remains in the

tunnel for virtually the entire length of 4,350 feet.

The adjacent as-built geologic profiles (Figures 8 & 9, Appendix A) is in the East-West

direction and shows the formation boundaries dipping downwards towards the east as

expected, at about 76 feet per mile. Also noted in the tunnel geologic maps are a series offault zones in between stations 405+40 and 400+43, a distance of about 500 feet. The

tunnel maps indicate the following fault zones:

Station 404+20 to 405+20; 11 faults trending northeast with offsets up to 10 feet and

up to two feet gouge width.

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Station 402+50 to 402+73; four faults trending northeast with offsets up to 2.2 feetand up to two feet gouge width.

Station 401+76 to 402+10; three faults trending northeast with offsets up to 1.6 feetand up to three feet gouge width.

Station 400+43 to 401+00; five faults trending northeast with offsets on one fault of15 feet, another to 15 feet and gouge thickness to 1.5 feet.

The total tunnel inflow at the time of mapping (do not know how long after initial

excavation) from station 400+25 to 405+50 was 313 gpm. The ground was supportedwith the design pattern of rock dowels, additional dowels, wire mesh, minestraps and

rolled channel pieces. No steel sets were placed in the 19.5 foot excavated diameter

tunnel.

It is believed that these North-East trending fault zones bound a series of blocks which

have been progressively displaced downwards on the north side of the fault zone.Additional evidence is provided on Figure 3, the 27 th Street Geologic Profile, where an

offset of the Racine-Waukesha Formation boundary of about 95 feet is observed between

boreholes I30-02-NS and WA-1, a distance of about 3,200 feet in a North-South

direction, i.e., generally along the regional strike and therefore expected to be sub-horizontal to horizontal. Similarly, on Figure 4, the Milwaukee River Geologic Profile,

an offset of about 80 feet is observed in the Waubakee-Racine Formation boundary

between boreholes I30-NS-AL-11 and CA-1, a distance of about 5,800 feet in a North-South direction. An offset in the same boundary (except upwards) of about 50 feet is

observed between boreholes CA-1 and CA-2, a distance of about 3,500 feet.Subsequently, the boundary is almost horizontal between boreholes CA-2 and CA-3.

This reversal of the fault throw direction indicates a graben effect, with blocks displaced

progressively downwards towards the north and then the sequence reversed with theblocks stepping upwards.

Further evidence of this fault zone is the deep, broad bedrock valley which appears totrend east- northeast and encompasses borings WA-1, CA-1 and CA-2. The faulting

previously discussed is most likely a significant contributory cause to the formation of

the bedrock valley due to preferential weathering and glacial scouring.

Groundwater

Water WellsGroundwater occurs in the post-glacial and glacial soils and in the bedrock. Highcapacity industrial wells are present (Table 3, Appendix A) in the study area; however,

their operating status has yet to be ascertained. Shallow domestic wells developed in the

near-surface soils also exist (Tables 2 and 3, Appendix A) and may still be used for lawnwatering.

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Bedrock Groundwater

The principal storage and means of transfer of groundwater in the Silurian dolomites are

the discontinuities, such as bedding, joints and fault systems. Solutioning of these

features provides greater capacity for storage and higher initial inflows when interceptedin tunnels. Experience in deep rock MMSD tunnels shows generally that when not

overlain by the Thiensville Formation (a major aquifer), the inflows diminish rapidlywith time as storage is depleted. Conversely, when overlain by the ThiensvilleFormation, such as in the North Shore Phase 1 tunnel, inflow rates were high and did not

attenuate rapidly. Solutioned openings, such as pipes yielding high inflows, were also

encountered in the Racine Formation in this tunnel [11].

Water pressure testing was conducted in all of the rock portions of the boreholes as

described in Field and Laboratory Testing Programs. The calculated permeability (used

interchangeably with hydraulic conductivity in this report) values are presented inAppendix D and selected values are shown at the test depth on the borehole logs. The

tests indicate a range of values in the Silurian dolomites from 1 x 10 -7 to 3 x 10-2 cm/sec.

The high values occur at the following locations: 3 x 10

-2

cm/sec in the RacineFormation from 229 to 249 foot depth in Boring CA-2; a value of 3.5 x 10-2 cm/sec for

the depth increment 197 to 237 feet in borehole CA-3. A fault was logged in this depth

increment. Generally, the values for the Silurian dolomites in boreholes WA-1, CA-1,

CA-2 and CA-3 were in the 1 x 10-5

cm/sec and higher range. However, borehole WA-2has a permeability value of 3.6 x 10-2 cm/sec for depth increment 229 to 249 feet in the

Racine and the remaining values in the range of 3 x 10-3 to 5 x 10-4 cm/sec.

As expected, the Devonian Age Thiensville Formation, which forms the top of rock at

boreholes WA-2 and CA-3, yielded very high permeability values ranging up to 1 x 10 -1cm/sec at borehole CA-3 and up to 1.6 x 10-3 cm/sec at borehole WA-2.

Groundwater in the dolomite typically occurs under confined or semi-confinedconditions. An artesian condition was encountered in borehole CA-2 in the core run from

227.5 to 236 feet depth. The water level rose to about 11 feet above the ground surface

when restricted into a one-inch diameter pipe and the flow rate was in the range of 30 to60 gpm. The rock is overlain by about 77 feet of very dense, gravelly silt with cobbles

(till) at this location which provided a very effective confining layer.

To provide information on groundwater levels, open stand-pipe piezometers were placedin boreholes WA-1 and WA-2. The recorded water elevations are shown in Table 2 and

presented on the boring logs.

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REFERENCES

1. North Shore Interceptor, Phase IIA, MMSD Contract No. I36G152. North Shore Interceptor, Phase 1, MMSD Contract No. 136G113. North Side High Level Relief Sewer, MMSD Contract Nos. I48G11, G13, G14,

G15 and As-Builts

4. Northeast Side Relief Sewer System East Branch, Contracts 287 and 288. MMSDContract No. I45541 and As-Builts for Contract 287 only

5. North Shore Interceptor Phase IIA Lining Report No. 26. Rust/Harza 2002 Eastabrook Parkway and Glendale Avenue Relief Project

Design Contract CO48DE001 Alternative Analysis

7. Singh, P.N., Tatioussian, S.V. and Flagg, C.G., 1983. A Study of GeotechnicalProperties of Milwaukee Area Soils, Geologic Environment and Soil Properties,

American Society of Civil Engineers, Geotechnical Special Publication, pp. 269-30.

8. Field Manual for Subsurface Exploration, prepared by HNTB9. Houlsby, A.C., 1990. Construction and Design of Cement Grouting, pp. 221-

222, J. Wiley & Sons.

10.Mikulic, Donald G. and Kluessendorf, J. Subsurface Stratigraphic Relationshipsof the Upper Silurian and Devonian Rocks of Milwaukee County, Wisconsin.

11.Pennock, E.S., Fradkin, S.B. and Ilsley, R.C., 1991. Impacts of SolutionFeatures on Mining of the North Shore Tunnel in Milwaukee, Wisconsin, in

Proceedings: Association of Engineering Geologists 34th Annual meeting,Chicago, pp. 38-47.

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APPENDIX A

Summary of Review of Geotechnical Reports and As-Builts

from MMSD Projects in the Study Area

CONTENTS

Introduction.................................................................................................................1

Study Area Geology-East and Central (Milwaukee River) Alignments.....................1

Physiography...................................................................................................1Soil ..................................................................................................................2

Rock................................................................................................................3

Groundwater Conditions in Soil .....................................................................5Groundwater Conditions in Rock ...................................................................7

Domestic and High Capacity Wells............................................................................8

Construction Experience...........................................................................................10

NSHLRS .......................................................................................................10Section 1............................................................................................10

Section 2............................................................................................10Encountered Ground Conditions and Excavation Rates...................10

NESRS (Contract 287)..................................................................................11

Study Area Geology- West (27th

Street) Alignment ................................................12Soil ................................................................................................................12

Rock..............................................................................................................13

Construction Experience: North Shore Phase IIA Tunnel........................................14

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APPENDIX A

SUMMARY OF GEOTECHNICAL INFORMATION AND

CONSTRUCTION EXPERIENCE IN THE STUDY AREA

INTRODUCTIONThe study area is bounded east to west by Lydell Avenue and 43

rdStreet and north to

south by Green Tree Road and Hampton Avenue. Within the study area, three north to

south corridors have been identified. These are the East Alignment along Lydell Avenue

(equivalent to 1st

Street); the Central Alignment along Sunny Point Road (equivalent to13th Street); and the West Alignment on 27th Street (meeting Hampton Avenue

somewhere between 27th and 32nd Streets).

Because of the relative lack of tunnel construction experience along the East Alignment

and the likely similarities in the soil and rock conditions, the East and Central Alignments

will be described together. The West Alignment merits a separate discussion. The

sources of information used are the Geotechnical Reports and As-Built Reports as listedbelow. The locations of these project alignments are shown in Figure 1 (Appendix A).

North Side High Level Relief Sewers, or NSHLRS, (Contracts I48G11, G12, G13,G14, G15); Geotechnical Report and As-Builts

Northeast Side Relief Sewer System East Branch, or NESRS, (Contracts 287 & 288[I45541]); Geotechnical Report and As-Built for Contract #287 only

North Shore InterceptorPhase IIA Main Tunnel Grouting (Contract I36G15);Tunnel Maps only

North Shore Interceptor (Contracts I36G11, 12, 13, 21, 22, 23, 24, 31, 32, 33, 34, 51,42, 51, 52, 53, 54, 55, 56, 57, 61, 62, 63, 64); Geotechnical Report

STUDY AREA GEOLOGY: EAST AND CENTRAL ALIGNMENTS

PhysiographyThe following is from the NSHLRS Geotechnical Report:

The area is underlain by gently dipping sedimentary rocks of

Paleozoic age. The bedrock surface has greater relief than that

of the present land surface as a result of preglacial and glacialerosion. The rock is almost entirely covered by soil deposits of

glacial and postglacial origin. The present relief is a composite

of bedrock topography, glacial landforms and changes caused

by erosion by streams, rivers, and Lake Michigan and by works

of man.

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SoilThe following discussion is from the NSHLRS Geotechnical Report. The alignment is

shown in Figure 2 (Appendix A). The following sections are referenced in the text:Section 1, Station 0+00 at Dropshaft NS-3 to Station 45+00 at Port Washington Road;

Section 2, Station 45+00 to Station 116+00 at 24 th Street.

In Section 1, the sewer will be installed in bedrock, a discussion

of which is presented in a later section of this report. The soils

overlying the bedrock in this area include fill of varying composition,

lacustrine clays and clay tills, generally in descending order. The fill

soils are generally limited in depth to the upper 10 feet of the profile

and vary texturally from silty sand and gravel to silty clay. Granular

fills are generally in a medium dense condition and clay fill is typically

in a stiff to very stiff condition

The lacustrine clays and clay till soils are typically found to be in a

stiff to hard condition. The latter soil type extends to the bedrocksurface, which occurs at depths of 8 to 30 feet below grade, generally

increasing to the north.

The soil conditions of Section 2 include four major soil types. The

surficial soils, extending to depths in the range of 5 to 10 feet, are fill

materials of variable composition and density. In the general area of Lincoln

Park, the fill is typically underlain, in order, by strata of silty sand alluvium

and silty clay of lacustrine origin. The sandy soils, a postglacial deposit, are

generally in a medium dense condition. The clay soils are generally in a stiff

to very stiff condition. The combined thickness of these soils extend to

approximately elevation 20.0 to 30.0 feet, terminating above the sewerenvelope. Further west in this section, the soils below the surficial fill are

generally postglacial granular alluvium. These soils, extending

approximately to elevations 25.0 to 30.0 feet and including fine, to fine to

coarse sands with variable silt content, are generally in a loose to medium

condition to depths of approximately 15 feet, and medium dense to dense at

greater depth.

Glacial lacustrine soils occur below approximately 20.0 to 30.0-feet elevation

throughout Section 2 and will comprise the sewer envelope soil. These soils

generally consist of horizontally laminated clayey silt and silt with occasional

layers of fine sand and silty clay. They are generally in a medium densecondition (granular soil) or stiff to very stiff condition (cohesive soil). These

lacustrine soils, in particular the silt soil, exhibit a high degree of dilatency

and are considered to be moderately to highly sensitive to disturbance. That

is, they experience a dramatic loss in strength upon remolding and are,

therefore, susceptible to disturbance by construction activities.

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The following discussion is from the Contract 287 Geotechnical Report. The alignmentis shown in Figure 3 (Appendix A). Of particular interest is the north-south section on

Green Bay Road and Green Tree Road and the east-west section along Green Tree Road

between Green Bay Road and Port Washington Road.

Based on the characteristics of samples recovered in the exploration programand a review of other construction projects in the area, this tunnel project can

be divided into several broad geologic settings. West of the Milwaukee River

the soil is dense, overconsolidated glacial till, characterized as Till 1. The

tunnel often cuts into overlying more clayey glacial deposits, Till 2. Till 2 acts

to confine the groundwater in the water bearing seams of Till 1. Groundwater

levels are above the crown in this setting.

Near the Milwaukee River, extensive alluvial sands and other river bed

deposits should be expected within the glacial sediments. Borings did not

yield samples of this type soil but it is likely that it exists. Groundwater levels

are above the crown in this area.

East of the river, clayey glacial sediments (till 2) predominate. Within these

sediments are extensive deposits of waterlaid stratified drift. These deposits

exhibit varves, or silty layers, which may tend to conduct large amounts of

water. Groundwater east of the river varies from above crown to below the

invert at the eastern extreme of the project.

Rock will be encountered near the beginning and end of the project. Mixed

face conditions govern at transitions. Top of rock may be weathered and

broken. A fault zone is possible at the rock section at the east end of the

project. Groundwater is above the crown in the western rock section and

below the invert in the eastern rock section. Pinnacles of rock may be

encountered between boreholes elsewhere, especially west of the river.

Extreme variability in soil and rock conditions with location should be

expected. Boulders, including possible granite glacial erratics, were not

encountered during exploration but are likely to be found during excavation.

RockThe predominant bedrock forming the top of rock in the study area consists of theMilwaukee and Thiensville Formations of Devonian Age. Figure 4 (Appendix A) is from

Reference 1 and is a map showing the extent of the outcrop of the Milwaukee,

Thiensville and Waubakee Formations. Below the Waubakee and increasing in age arethe Racine, Waukesha and Mayville Formations. However, the Mayville will not beintercepted in the East and Central Alignments. Table 1 of Appendix A (Table 3-6 Area

Stratigraphic Section) shows the thicknesses of the formations and Figure 5 (Appendix

A) is a geologic section of the North Shore Phase II tunnel in the east-west direction,generally along Hampton Avenue until about Station 405+00 where the tunnel turns due

south beneath 32nd

Street and terminates at NS-12 Dropshaft at Capitol Drive. The

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following rock formation descriptions are from the North Shore Interceptor GeotechnicalReport.

Milwaukee Formation

The Milwaukee Formation has been subdivided into units based upon

differences in lithology. The Milwaukee 1 (Mil-1) unit is a green, soft,pyritiferous mudstone that slakes or breaks down rapidly when immersed in

water (Appendix B). It forms the bedrock surface at the Humboldt Yards

access shaft site. The bedding plane spacings are predominantly close. The

Milwaukee 2 (Mil-2) unit is a greenish, gray argillaceous dolomite that

becomes highly argillaceous towards the base. It forms the bedrock surface

at Sites NS-7, NS-6 and NS-5. The Milwaukee 3 (Mil-3) unit is generally a

greenish gray, moderately soft to hard, occasionally very soft dolomitic

mudstone with close to medium bedding and is not susceptible to slaking

(Appendix B). The Milwaukee 4 (Mil-4) unit is a greenish gray, hard,

argillaceous dolomite, with close to medium bedding and occasional thin clay

partings. It forms the bedrock surface at the sites of dropshafts NS-3, NS-8and NS-11 and the Schlitz Terminal access shaft.

Thiensville Formation

The Thiensville Formation consists of interbedded dolomites and limestones

with occasional mudstone beds. The dolomite beds vary from brown

(generally bituminous) to gray and from slightly to highly weathered. The

limestone beds are weathered and solutioned. A weakly cemented, breccia

has been noted principally at the base of the formation, but occasionally

above the base. It consists of angular fragments of dolomite and limestone in

a silty clay matrix.

Tunnel mapping in local projects and cores from this project indicate that the

lower part of the Thiensville Formation is weathered. Mapping in MMSD

Contracts 289 and 867 north of the North Shore Interceptor site revealed that

various beds were subaerially weathered before the deposition of overlying

beds. The degree of weathering ranged from moderate to high. One of the

features mapped was a 50-foot long crevice filled with rock debris and

cemented by secondary calcite. Boring evidence of weathering includes high

core loss and weathered samples.

The contact between the Thiensville Formation and the underlying Waubakee

Formation is an unconformity. The bedding above and below the

unconformity are essentially parallel. Mapping in MMSD tunnel contract 867

indicates that locally the unconformity is an undulating surface with an

amplitude of 1 to 2 feet. The average dip of the unconformity appears to be

parallel to the dip of the adjacent formations. Borehole pressure testing of the

unconformity and the adjacent Waubakee formation resulted in permeability

calculations as high as 2x10-3

cm/sec. This indicates that the unconformity

could yield high groundwater inflows.

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Waubakee Formation

The Waubakee Formation is a very close to closely bedded dolomite with thin,

alternating brown and light and dark gray bands. The typical bedding plane

parting is very thin shale across which the core readily separates giving

smooth, planar surfaces. Low RQD values generally reflect the presence ofnumerous bedding plane partings. The bedding planes are generally

horizontal but dips of up to 25 degrees were measured in core from I30-NS-

MR-4D, about 1,100 feet east of the alignment where the Waubakee Strata are

flank beds on a Racine formation reef.

Racine Formation

The Racine Formation is a uniform, light gray, dense dolomite with bedding

plane spacings that range from close to medium. There are occasional zones

of very closely spaced, thin, shaly partings and rock containing small pores or

vugs.

A reef was encountered in borings 130-NS-DS-6, I30-NS-MR-4D and MI-5,

with an extent of approximately 1,500 feet in an east-west direction. The reef

rock is generally vuggy throughout with several zones of coarse vugs.

Pressure testing in borehole I30-NS-DS-6 gave permeabilities ranging from

1x10-3

to 5x10-4

cm/sec for the reef rock.

Waukesha Formation

The Waukesha Formation, generally a dense, gray dolomite, is divided into

three units on the basis of lithologic variations as shown below. Unit WA-1 is

generally dense, very close (less than 0.2 foot) to close (0.2 to 1.0 foot)

bedded, and cherty. Its midportion is typically fossiliferous, finely vuggy and

medium bedded. Unit WA-2 is characterized by the general absence of chert.

The top part is medium to widely bedded with stylolites and is generally

fossiliferous and finely vuggy. The bottom part of the unit is very close to

close bedded with shale partings and is dense. Unit WA-3 is a light gray,

dense dolomite and is very close to close bedded with thin shale partings.

Chert occurs as coarse nodules and layers throughout the unit. Bedding

plane fillings in the Waukesha Formation are predominantly shale and range

up to 0.05 inch in thickness. Most of the other fillings are clay with mean

thicknesses of 0.25 inch in Unit WA-1 and 0.02 inch in Units WA-2 and WA-3.

Groundwater Conditions in SoilThe following discussion is from the NSHLRS Geotechnical Report and applies to thealignment shown in Figure 2 (Appendix A).

GROUNDWATER CONDITIONS IN SOIL

The soil deposits in the area form a generally complex stratigraphy, and an

equally complex arrangement of aquifers and aquicludes. The soil aquifers

usually consist of sand and gravel zones, of alluvial deposits or outwash

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deposits or occasionally sandy and silty lacustrine deposits. The alluvial

aquifers are located in the lowland areas along the valley courses of rivers

and streams. They can be extensive and continuous within those confines.

The glacial aquifers are considerably more widely distributed and indefinitely

defined.

On a local scale, individual soil aquifers can be confined or unconfined,

depending upon the nature and extent of surrounding deposits of soil and

rock. The confining soils are generally clayey till and clayey lacustrine

deposits. The grain size distribution of all the soil deposits can vary, which

changes their effectiveness as aquifers or as confining layers. This is

particularly true of till deposits. The hydraulic properties of permeability,

transmissivity and specific storage of the glacial and postglacial aquifers can

vary greatly.

The soil aquifers are recharged primarily by infiltration of precipitation and

water from rivers and streams. Groundwater discharge from the soil aquifersis primarily to streams, rivers and the underlying bedrock. The

potentiometric heads in nearby soil aquifers may differ from each other or

from the head in nearby unconfined aquifers, or from the position of the water

table.

Groundwater flow through the soil aquifers is dependent on their grain size

characteristics, their extent, the degree of confinement provided by

surrounding aquicludes, and their connection to sources of recharge. In

addition, all of the glacial soils may include layers or pockets of permeable

soils that could produce groundwater inflow. Fine-grained deposits of

alluvial and sandy or silty lacustrine soils, such as occur along the Milwaukee

River and Lincoln Creek, have all, on occasion, been observed to loosen in

boreholes when hydraulic pressures were not maintained above in-situ

hydrostatic pressures. This indicates that these soils may become unstable

even under low hydraulic gradients.

The results of permeability tests performed in piezometers and observation

wells in soil indicate permeability coefficients ranging from about 4x10-6

cm/sec to 1x10-4

cm/sec (refer Table 2). Higher permeability coefficients

could be expected in sandy lacustrine deposits or in outwash deposits. One

test was performed in alluvial deposits along Lincoln Creek and indicated a

permeability coefficient of 4x10-3

cm/sec.

The generally low measured permeability coefficient of the soils indicates that

dewatering by use of gravity wells or vacuum assisted wellpoints would

probably not be effective, except for shallow depth excavations in the more

coarsely grained alluvium along Lincoln Creek.

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In the area of the C&NW Railroad crossing of the Milwaukee River, which

corresponds to the alignment crossing the river approximately between

stations 69+90 and 71+90, the 10-year flood is estimated to cause a rise in

river level to about elevation 39 feet, and the 100-year flood is estimated to

cause a rise in river level to about elevation 42 feet {12}. In the river channel

areas, groundwater level elevations in the soil are generally about equal tothe surface water levels in the Milwaukee River. In the upland areas,

groundwater levels range up to elevation 75 feet (generally 5 to 15 and

occasionally as deep as 30 feet below ground surface). Water levels

measured in piezometers and observation wells along the North Side High

Level Relief Sewer system are listed in Table 4.

The following discussion is from the Contract 287 Geotechnical Report. Refer to Figure

3 o f Appendix A for the alignment.

West of the Milwaukee River, water level observations indicate full saturation

along the proposed interceptor and a water table configuration consistentwith the general groundwater gradient toward the Milwaukee River. Water

levels vary from near ground surface to about 20 feet below surface.

In general, sand content of Pleistocene deposits is higher and more uniformly

distributed on the west side of the Milwaukee River than elsewhere along the

project. For purposes of evaluating interceptor and shaft dewatering

feasibility, the deposits west of the river should be treated as one

hydrogeologic unit.

East of the Milwaukee River, water levels are generally near tunnel crown

elevations or lower. Depth of water ranges from about 30 feet to about 85

feet below the surface. Ten test borings are dry. The water level in hole EB-

17 appears anomalous. Based on water levels measured in adjacent test

borings and type of material logged in this hole during drilling, it is believed

that the high water elevation measured in boring EB-17 is due to piezometer

construction rather than groundwater conditions.

Neglecting this irregular water level observation, the general trend of

groundwater slope is from the Milwaukee River toward Lake Michigan.

Groundwater Conditions in RockThe following discussion is from the NSHLRS Geotechnical Report and refers to

expected conditions in the Thiensville Formation only. The alignment discussed is thatportion in rock and mixed face described as Section 1 previously, i.e., from Station 0+00at NS-3 Dropshaft to Station 45+00 at Port Washington Road.

The piezometric head observed in boring ULC-3 is approximately 28 feet

above tunnel crown and appears to generally coincide with the level of the

Milwaukee River at the alignment crossing in Estabrook Park. Measured

piezometric heads in borings ULC-5A and ULC-5B are at approximately 21

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feet to 25 feet above tunnel crown. This data indicates that piezometric levels

in the upper bedrock are at or near the river levels.

Hydraulic pressure (packer) testing of the Thiensville Formation indicates

permeability coefficients ranging from 1x10-5

cm/sec to 3x10-3

cm/sec. A

summary of results for these tests is presented in Appendix E. Permeabilitycoefficients within the tunnel envelope range from 1x10-4

cm/sec to 3x10-3

cm/sec. In addition, analysis of pump test data from the construction of the

Schlitz Terminal Access Shaft of the Inline Storage System (adjacent to the

NS-3 site) near the south end of the alignment indicates a range of

permeability coefficients from 1x10-1

cm/sec to 9x10-3

cm/sec. Design of the

dewatering system for the Thiensville Formation by the use of deep gravity

wells along the southern portion of the alignment from Station 0+00 to

approximately 19+00 should consider, amongst other constraints, the terrain,

the river crossing, the high rock-mass permeability and transmissivity, and the

proximity to the river which is a direct source of recharge to the rock. The

design of a dewatering system north of Station 19+00 should consider thepotentially high rock-mass permeabilities and transmissivities, and the

presence of domestic wells in the alignment vicinity (refer Appendix H for

locations). The use of compressed air to control groundwater inflow

throughout the rock portion of the tunnel appears to be technically feasible.

Refer to the section Surface Constraints for further discussion regarding

these wells and the use of compressed air.

The groundwater table was encountered at depths in the range of 2.2 feet to

28.3 feet below present grades. A tabulation of groundwater levels observed

in each of the piezometer/observation well installations along the alignment is

presented in Table 4.

The following general discussion of the Dolomite Aquifer which includes the Devonian

and Silurian Age Formations and applies generally to the existing North Shore Phase II

alignment along Hampton Avenue (refer to Figure 5 of Appendix A). A review of thepacker test data for the exploration borings along the North Shore Phase II alignment

show that for the Waubakee Formation the measured permeability was generally in the

range of 4x10-3 to > 1x10-7 cm/s; and for the Racine and Waukesha Formations generally

in the range of 7x10-5

to > 1x10-7

cm/s. A further evaluation of potential water inflowsduring construction will be discussed below based on tunnel mapping of the North Shore

Phase II Tunnel.

DOMESTIC AND HIGH CAPACITY WELLSThe location and concentration of domestic wells is useful information from a potential

project impact viewpoint as is the location of high capacity wells (>10,000 gallons/day)which may have industrial use. Figure 6 (Appendix A) is from the Contract 287 and 288

Geotechnical Report presents an overview of the density of the domestic wells and the

location of the high capacity wells. The current activity status of the high capacity wells

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is not known. The following discussion is from the Contract 287 and 288 GeotechnicalReport.

EXISTING DOMESTIC WATER SUPPLY WELLS

Logs were located for 217 domestic water supply wells within one mile of theproposedalignment were located [sic]. The logs are part of well

constructors reports submitted to the Wisconsin Department of Natural

Resources. These wells can be located by use of State Plane Coordinates.

The number assigned to each well is for identification and can be used in

conjunction with the original well logs. These logs can be reviewed by

appointment at the PMO. Well construction information includes the

following parameters: drawdown after initial well test, depth of surface

casing, and lithology and length of production zone. The drawdone and

specific capacity of each well were calculated and tabulated (Tables E-1 and

E-2, Appendix E).

The total depth of the wells ranges between 73 and 460 feet. The production

zone thickness is reported to be from 4 feet to 292 feet. Although no

correlation was established between length of production zone and well yield,

it seems that wells with long production zones also demonstrate large

drawdowns (or small specific capacities). Well yields at time of completion

ranged from about 7 to 50 gpm.

Few of the domestic wells exhibited confined (or artesian) conditions at time

of completion. No such wells were recorded within two miles of the proposed

tunnel.

The domestic well logs can be used to confirm and verify depth to top of

bedrock in places where test borings did not penetrate bedrock. Well drillers

logs must be assigned a limited reliability because of the crude mode of well

installation.

Each property along West Green Tree Road (between the Milwaukee River

and Port Washington Road) has its own well. Based on conversations with

home owners in the area, it was determined that these wells have quite

uniform characteristics. Most are about 100 feet in total depth and were

drilled into the upper part of the bedrock. At the time of completion, these

wells yielded between 10 and 30 gpm.

Appendix H of the NSHLRS Geotechnical Report lists wells indicated to exist within

1,000 feet of that alignment. These locations are presented in Tables 2 and 3 ofAppendix A.

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CONSTRUCTION EXPERIENCEThe following information is derived from the As-Built Profiles for tunnels and

constructed in the study area.

NSHLRS

The NSHLRS was constructed under two separate contracts.

Section 1

Section 1 extends from Station 0+00 at the NS-3 Dropshaft to Station 45+00 at Port

Washington Road and was principally excavated within the Thiensville Formation.Sections 2, 3 from Station 45+00 to Station 116+00 at 24 th Street was the second

contract. Section 1 was excavated to a 10.5 foot diameter using a Robbins Tunnel Boring

Machine (TBM) except for the last (approximately) 200 feet which was excavated bydrill and blast. This was because high water inflows washed the fines out of the mined

rock in the face into the tunnel invert from where it had to be hand-mucked. The

contractor did not attempt to dewater and submitted a claim for an alleged Differing Site

Condition. The peak water inflow experienced was 1100 gpm at Station 7+00. Themixed face conditions were excavated using a shield with drill and blast.

Section 2

Section 2 from Station 45+00 to 116+00 at 24th Street was excavated at 7.5 feet diameter

using a Lovat TBM equipped with flood doors (can be closed to prevent soil/water

inflow) and pressure relief gates which are hydraulically operated gates within theplenum that are used to control the amount of soil exiting the plenum onto the conveyor.

The system affords good ground control when in poor soil conditions and can be opened

up when in good ground conditions. Of the three river crossings, two were made inopen cut and one completed by tunneling under the Milwaukee River, which was 250 feet

wide at this point. The tunnel support throughout was provided by jacked concrete pipe.From Station 45+00 to 76+00 the finished diameter was seven feet. From 76+00 to

Station 214+00 the finished diameter was six feet.

Encountered Ground Conditions and Excavation Rates

The excavation for the seven-foot diameter jacked pipe tunnel between Station 45+00 to

76+00 encountered Grey sandy clay. Progress rates ranged from 16 to 96 feet and

averaged 52 feet per one-day shift (assumed to be eight hours). There was no indicationof wet conditions. The tunnel depth was approximately 42 feet over this length, reducing

to 32 feet beneath the Milwaukee River. The overall continuous pipe jacked length was

about 1,450 feet.

The excavation for the six-foot diameter jacked pipe tunnel between Station 75+00 to

89+50 (just east of Lincoln Creek Crossing No. 1) encountered principally silty clay,

occasionally soft and wet with a few boulders on one shift. Progress ranged from 7.5 to90 feet and averaged 47 feet per shift (assumed eight hour shift). The total length of

continuous jacked pipe was 1,160 feet.

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The section between stations 95+66 to 115+14 at the east side of Lincoln Creek crossingNo. 2, encountered primarily silty clay which was wet for 57% of the total length of

1,918 feet. The excavation rate ranged from 17.5 to 73 feet with an average of 32.5 feet

per shift. The depth of cover to the tunnel invert averaged about 28 feet.

The 1,258 foot section between stations 119+05 and 131+63 at Villard Avenue and 27

th

Street, encountered principally damp, sticky, silty clay, in lumps: cobbles and boulderswere encountered over a length of 105 feet (8.5% of length).

The excavation rate ranged from 7.5 to 45 feet and averaged 29 feet per shift. The depth

of cover above the tunnel invert averaged about 22 feet. The occurrence of sticky claylikely had an adverse affect on tunnel excavation rates. Note that the majority of this

tunnel excavation was completed in the flood plain of the Milwaukee River and Lincoln

Creek at shallow depths up to 42 feet. The soils encountered were silty clay and sandyclay, with very occasional sands and no gravel and few cobbles and boulders. These soils

are described as glacial lacustrine deposits in the project Geotechnical Report.

NESRS (Contract 287)The 12,080 feet of eight-foot diameter tunnel for the NESRS was excavated using a

Lovat TBM, with the same capabilities as that TBM described for the NSHLRS, andsupported with ribs and lagging at four-foot centers. A small section in rock at Station

0+00 (discussed in more detail under the West Alignment) was hand-mined and the

Milwaukee River Crossing was in open-cut excavation.

The following discussion relates to the section of the alignment from Station 34+80 at

Green Bay and Mill Road north along Green Bay Road to the junction with Green TreeRoad at Station 61+50. The tunnel was excavated in Till 1 which is very hard, very

consolidated silt, gravel with cobbles and boulders and virtually dry; it lies directly on theThiensville bedrock. Occasionally the overlying Till 2 would dip down into the tunnel.

The Till 2 consisted of either moist clays or wet sand and/or gravel. Excavation rates inthe Till 1 averaged 43 feet and ranged from four to 96 feet per shift (assumed to be eight

hours). At two locations, wet sand and gravel in the crown led to sink holes, the larger

being about 60 feet long and seven feet deep. Ground modification using chemical groutwas done. The tunnel progress was impacted such that over a period of 11 days the

average progress was 15.5 feet and ranged from six to 29 feet.

From Station 61+50 to 75+65 (west of Milwaukee River Crossing) and from 86+90 at N.

River and Green Tree Roads, to station 120+80 at Green Tree and Port Washington

Roads. The tunnel was excavated in Till 1. At two locations, wet sand and gravel wasintercepted that led to major sinkholes, both about 10 feet deep and 70 feet long. Somechemical grouting of the tunnel ahead of the excavation was done between the sinkholes.

Rock was intercepted in the invert at two locations: one 60 feet, the other 155 feet long.

It appears the TBM was able to excavate through the rock with some blasting. All of thedomestic wells along the section from station 86+90 to 113+00 were dried up by the

project dewatering and were serviced by tanker truck. Excavation rates for 4,800 feetaveraged 70.5 feet per shift and ranged from four to 164 feet per shift.

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STUDY AREA GEOLOGYWEST ALIGNMENTThis alignment extends along 27th Street in a northerly direction from Hampton Avenuebetween 27th and 32nd Street, to an east-west line of Green Tree Road extended (about the

junction with Vera Street). This alignment has the following differences with the Central

and East Alignments:

It is the furthest away from the Milwaukee River, Lincoln Creek and their confluence. The predominant soils are likely to be Till 1 on bedrock and overlain by Till 2 with

very little recent post-glacial soils.

The Thiensville Formation forms the TOR and is closer to the ground surface in theMill Road vicinity.

The density of domestic wells decreases, but four highcap wells are shown on Figure6 of Appendix A.

The thickness of Thiensville diminishes towards the west and the contact with theWaubakee Formation is closer to the ground surface as shown in Figure 5 (Appendix

A).

The differences will generally be advantageous to construction of the deep tunnelalternative. The high top of rock presents problems for a large diameter shallow tunnel.

SoilThe following description is from the NSHLRS Geotechnical Report. The alignment is

shown in Figure 2 (Appendix A). Sections 3 and 4 are from Station 116+00 at 24 th and

Villard Avenue, north along 24th

to Station 214+60 at Mill Road and Sydney Place. Thesoils are described as follows:

Glacial lacustrine soils occur below approximately 20.0 to 30.0 feet elevationthroughout Section 2 and will comprise the sewer envelope soil. These soils

generally consist of horizontally laminated clayey silt and silt with occasional

layers of fine sand and silty clay. They are generally in a medium dense

condition (granular soil) or stiff to very stiff condition (cohesive soil). These

lacustrine soils, in particular the silt soil, exhibit a high degree of dilatency

and are considered to be moderately to highly sensitive to disturbance. That

is, they experience a dramatic loss in strength upon remolding and are,

therefore, susceptible to disturbance by construction activities.

Glacial till soils are the predominant soil type in Section 3, extending

approximately from 24th

Street to the southernmost crossing of the Soo Line

railroad. Excluding a limited amount of overlying lucustrine and alluvialsoils (as described for Section 2 above) occurring near the east end of Section

3 (refer to borings ULC-13, ULC-13A and ULC-13B) and isolated fill and

topsoil deposits near the surface, the soils of the area are generally moderate

strength, low to moderate plasticity, silty clay. These soils generally exhibit

unconfined compressive strengths in the range of 2 to 3 tsf. Occasional lenses

of lacustrine silt and clayey silt were observed interlayered with the till.

These soils contain a trace of sand and gravel and the occurrence of boulders

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or cobbles is considered infrequent, none having been encountered in the

borings in this area.

Till soils are also the predominant soil type in the northernmost portion of the

alignment, Section 4. However, two distinctly different till types occur. The

upper portion of the profile (generally extending 20 to 40 feet in depth) issimilar to that described for the preceding section and consists of moderate to

high strength clay till. At greater depth, a second till with texture ranging

from sandy clayey silt to sandy silt occurs. This soil type is characterized by a

much greater sand and gravel fraction and an extremely dense condition.

Boulders and cobbles are known to be prominent in this latter till. The

borings in this section were terminated in this till except boring ULC-22 at the

northern terminus of the Upper Lincoln Creek alignment which encountered

bedrock at a depth of 64 feet.

The Geotechnical Report for Contract 287 NESRS describes the glacial soils along the

alignment between Station 0+00 at Mill Road and Sydney Place and 34+80 at Mill Roadand Green Bay Road as follows:

Till 1 is composed primarily of sand and silt mixtures with random cobbles

and boulders. It is generally found directly above bedrock along most of the

alignment. It is overlain by Till 2. Till 1 is generally gray to gray-brown. It

is a hard, dense soil with a water content lower than that of the overlying soil.

It is assumed that Till 1 is a remnant of the first stages of Wisconsin glaciation

in the region.

Till 2 underlies surficial fill at most boring locations. Till 2 is primarily

clayey silt. Silts are more predominant west of the Milwaukee River. Some

lenses of sand and gravel occur in Till 2. Generally, it is less dense and more

moist than the underlying Till 1. Till 2 is considered to have been deposited

from one of the later glacial stages of southeastern Wisconsin. It is generally

brown to gray-brown. In the literature, it has been described as buff-colored.

These deposits are less compressed and consolidated than the older

underlying material. Till 2 contains lenses of waterlaid stratified drift.

RockFigure 5 (Appendix A) is the geologic profile of the North Shore Phase II Tunnel which

is generally east-west along Hampton Avenue. At about Station 405+00 the tunnel turns

due south down 34

th

Street. Also, at Station 405+00 the invert of the tunnel is at thestratigraphic boundary between the Waukesha Formation overlying the MayvilleFormation. The Racine Formation forms the top of rock. No packer tests were done in

borehole I30-2-NS, the only deep boring at this location. A tunnel bored to the north

along 27th

Street at this same depth would likely be at or slightly above theWaukesha/Mayville boundary. The Waukesha has been described previously, the

following description of the Mayville is from the North Shore Interceptor GeotechnicalReport.

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Mayville Formation

The Mayville Formation is a light gray and gray mottled dolomite, with light

brown, finely vuggy nodular zones. Many of the vugs are coarse and clay- or

gypsum-filled. The formation becomes dense towards its base. It is close to

medium bedded with thin shaly partings.

About 35 percent of the bedding plane fillings recovered during coring areclay with a mean thickness of 0.22 inch. Shale fillings constitute more than 50

percent of the remaining filling types, with a mean thickness of 0.10 inch.

CONSTRUCTION EXPERIENCE: NORTH SHORE PHASE IIA

TUNNELThe tunnel was excavated to a diameter of 19.5 feet. Figures 7, 8 and 9 of Appendix A

are As-Built geologic profiles which were included in the North Shore Interceptor PhaseIIA Lining Report No. 2. Figure 7 shows that on the north-south leg from about Station

453+50 to 410+00 the tunnel was excavated along the boundary of the Waukesha and

Mayville Formations. A vuggy zone several feet thick which yielded residual flows up to

about 250 gpm (Figure 10 of Appendix A) was present continuously along this 4,350 feetlength of tunnel. Figure 8 shows the tunnel turning 90 degrees to an east-west direction

and indicates faulting. Geologic tunnel maps indicate a series of fault zones over about500 feet, extending from Station 405+40 to 400+43. The tunnel inflow in this tunnel

length at the time of mapping was 313 gpm, but was certainly higher when first

excavated by the TBM. The ground was supported by the design pattern of rock dowels,

additional dowels, wire mesh, mine straps and rolled channel pieces. No steel sets wereplaced. A fault was intercepted at Station 371+75 and when mapped, an inflow of 200

gpm was estimated.

Figure 9 shows the tunnel passing upwards through the boundary between the Waukesha

and Racine Formations and continuing east in the Racine Formation before turning southto join with the 32-foot diameter North Shore Phase I tunnel. Note that Boring I30-NS-AL-11 is very close to the junction of the central alignment (Milwaukee River) and the

North Shore Phase IIA Tunnel. The report also indicates that the frequency of solutioned

bedding planes was higher than anticipated in the Geotechnical report. An example isgiven of a single bedding plane intersected between about Stations 329+00 to 306+00

which was solutioned for much of its length, in parts up to one to two feet wide. Portions

of the bedding plane were filled with red claystone and the open portions produced

significant amounts of groundwater inflow. A summary of water inflows into the tunnel,measured on three different occasions in the period 12/19/89 to 2/19/92 are presented in

Table 4, Sheets 1 and 2. A histogram showing the cement (sacks) per 100 feet of tunnel

placed during the post-excavation grouting program is presented in Figure 11 (AppendixA).

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8/9/2019 Port Washington Road Relief Sewer V

Port Washington Road Relief Sewer Vol III

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Transcript of Port Washington Road Relief Sewer Vol III