Rutherfordton WWTP Capital Needs Review 7-21-15 · Rutherfordton WWTP Capital Needs Report, July...

ENGINEERING REPORT

TOWN OF RUTHERFORDTONWWTPCAPITAL NEEDS REVIEW

PREPARED FOR:

JULY, 2015

PREPARED BY:

170 TIMBERLAKE DRIVE

BOSTIC, NC 28018

Introduction ............................................................................................................................... ................... 3

Facility Overview............................................................................................................................... ............ 3

Evaluation of Plant Process Equipment ........................................................................................................ 3

Planned Capital Improvement Projects ........................................................................................................ 7

Discussion of Current Facility Operation ...................................................................................................... 7

Analysis of Cost of Treatment....................................................................................................................... 7

Conclusions and Recommendations ............................................................................................................. 9

List of Figures ............................................................................................................................... ............... 11

Supporting Documents ............................................................................................................................... 17

Operational Cost Projections .................................................................................................................. 18

Mechanical Component Testing ............................................................................................................. 19

WWTP Budget Information..................................................................................................................... 24

Rutherfordton NPDES Permit.................................................................................................................. 27

Rutherfordton Land Application Permit ................................................................................................. 40

Rutherfordton WWTP Capital Needs Report, July 2015

of 58

INTRODUCTIONThe Town of Rutherfordton recently expanded their waste water collection system to include service tothe Tryon International Equestrian Center and is considering adding additional customers as developmentoccurs in western Rutherford County. In order to ensure consistent compliance with the Town’s NPDESpermit as influent flow levels increase due to collection system expansion, an evaluation of thewastewater treatment plant was conducted to identify areas for improvement and providerecommendations for management of the facility. This report provides specific capital improvement andprocess modifications to allow for adequate treatment as average daily dry weathers flows increase to1.0 million gallons per day and 2.0 million gallons per day respectively.

FACILITY OVERVIEWThe WWTP is a 3.0 million gallons per day (MGD) capacity municipal wastewater treatment plant(extended aeration biological treatment process) consisting of influent screening, 10 million gallon (MG)aerated flow equalization basin, two (2) 1.5 MG extended aeration basins with floating surface aerators,two (2) secondary clarifiers, two (2) 60 hp return activated sludge pumps, chlorine contact chamber withsodium hypochlorite disinfection and sodium bisulfite de chlorination with post aeration.

Flow to the WWTP has been stable over the past three years and currently treats an average of 0.6 MGD.

EVALUATION OF PLANT PROCESS EQUIPMENTThe WWTP has a variety of both old and new process equipment, some of which is in need of immediatereplacement and others that will need replacing either in the next five years regardless of future flowrates or replacement once average daily flows exceed 1.0 MGD regardless of the time frame. Once theseimprovements are complete, the facility should be able to treat flows up to the design capacity of 3.0MGD consistently.

The major process equipment that is needed on a continuous basis to ensure consistent compliance withthe NPDES permit is shown in Table 1 on the following page. The current status of select critical processequipment is shown in Table 2, and a schematic that shows the location of the specific items relative tothe process flow stream is shown in Drawing 1.


of 58

Table 1: Summary Condition of WWTP Process Equipment.

Description Condition Comments

Manual Influent Screen Poor – Metal Grates Need Replacing See Figure 1.

Lakeside Equipment Microstrainer Fair – main unit in good condition, ancillaryequipment needs re painting

Unit is only sized to process a peak flow of1.255 MGD. Unit will need to be replacedto accommodate the permitted designflow of 3.0 MGD. See Figure 2.

Generac 500 KVA Stand by Generator Fair

Engine and drivetrain parts are not readilyavailable for repair – recommend replacingentire unit. Unit is budgeted forreplacement.

10 Hp floating aerators (Aqua Aerobic) inEQ Basin

Poor to unknown. The units have not beenoperated in several years.

Plant personnel report none of the unitshave been operated for several years. Theunits were placed into test operation andthe results are listed in Table 2. See Figures3 and 4.

Aeration basin – EQ Basin Flow splitter box Structurally sound. Valve operatordamaged and needs replacement.

Recommend installation of an adjustableby pass weir to allow for influent flowcontrol. Figure 5.

25 Hp floating aerators (Aqua Aerobic) inAeration Basins Fair condition. All are operable.

Results of electrical testing are listed inTable 2. See Figures 6 and 7.

Four (4) more aerators must be purchasedto allow for treatment of flows 1.0 MGDand greater.

Aeration Basins

Unit 1 in good condition – Unit 2 is off linedue to damaged liner. Liner must bereplaced before being placed back on line(scheduled for 2017).

Fencing around both units needs to bereplaced.

See Figure 8.

Secondary ClarifiersUS Filter Tow Bro Sludge collectionequipment

Poor condition. Only 1 unit in operation.Weirs are uneven and leaking. Concrete incollection troughs is broken. Unit 2 shouldbe placed back into operation when flowreaches 1.0 MGD

See Figures 9 and 10.

Return Activated Sludge Pumps60 hp – VSD

Two units in operation, a third new pumpis stored on site as a back up. Units are ingood operating condition, but the VSDfunction is not being utilized. VSDoperation should be implemented whenflows reach 1.0 MGD

Aerobic Digester

Tank is in good condition. Several leaksexist where supernatant draw off lineswere installed. Need to confirm conditionof aerators.

See Figure 11.

Chlorination/De chlorinatorTanks and related equipment in goodcondition. Recommend replacement ofmetering pumps.


of 58

Table 2: Results of Electrical Tests on Select Process Equipment

Unit Description Operating Condition & Comments

Aeration Basin #1 25 Hp Floating Aerator#1

Fair Condition – Amp Draw withinNameplate Tolerances















EQ Basin – 10 Hp Floating Aerator #1 Not Operational – Repair or Replace

EQ Basin – 10 Hp Floating Aerator #2 Fair Condition – Amp Draw withinNameplate Tolerances

EQ Basin – 10 Hp Floating Aerator #3 Not Operational – Repair or ReplaceEQ Basin – 10 Hp Floating Aerator #4 Not Operational – Repair or Replace








EQ Basin – 10 Hp Floating Aerator #12 Poor Condition – Repair or Replace


of 58

DATE: July 2015

170 TIMBERLAKE DRIVEBOSTIC, NC 28018

828.245.9674

PROJECT: RFTN WWTP

PAGE 1 OF 1

REVI

SIO

NS

REVI

SIO

N D

ESCR

IPTI

ON

DATE

NO

.

DRAW

ING

1:RU

THER

FORD

TON

WW

TPO

VERA

LL L

AYO

UT

RUTH

ERFO

RDTO

N W

WTP

RUTH

ERFO

RD C

OU

NTY

, NC

PRO

JECT

TIT

LE

PRO

JECT

TIT

LE

PROFESSIONAL ENGINEERINGCERTIFICATION

EQUALIZATION BASIN

AERATION BASIN #1

AERATION BASIN #2

HEADWORKS (BARSCREEN AND INFLUENT CHANNEL)

LAB/OPERATOR BUILDING

10 HP AERATORS (9 TOTAL)

CLARIFIER #1

CLARIFIER #2

CHLORINATION/DECHLORINATION

AEROBICDIGESTER

25 HP AERATORS(6 IN BASIN #1)

25 HP AERATORS(2 IN BASIN #2)

STORAGE

EQ BASIN FLOWSPLITTER BOX

RAS (RETURN ACTIVATEDSLUDGE) PUMPS

Feet0 40 80

PLANNED CAPITAL IMPROVEMENT PROJECTSThe Town’s current capital improvement plan includes the following items for the WWTP:

Replacement of Aeration Basin #2 HDPE liner in 2017 for $39,000,Replacement of WWTP generator in 2017 for $175,000,Installation of a SCADA system in 2019 for $115,000.

In addition to the planned projects, there are numerous other projects that must be completed as plantflows increase. Some of these projects supersede the planned projects in the CIP, and a detailed list andassociated costs of these projects can be found in the “Conclusions and Recommendations” section of thisreport.

DISCUSSION OF CURRENT FACILITY OPERATIONThe WWTP is operated under contract to Suez Water, which provides the Operator in Responsible Charge,additional certified operators, all laboratory analyses required for both the NPDES discharge permit andResiduals Land Application permit and daily minor maintenance of the facility. Major maintenanceactivities are the responsibility of the Town with assistance from Suez Water staff. The facility is staffedseven days per week year round.

The WWTP is well operated and maintained. All effluent limits are met on a consistent basis, with overalltreatment removal efficiency better that 95% for BOD5, TSR and Ammonia Nitrogen.

WWTP Residuals are land applied by private contractor. The current land application permit allows forsufficient capacity to dispose of residuals that are generated by flows up to 3.0 MGD, so no modificationsor changes are recommended.

ANALYSIS OF COST OF TREATMENTProjection of future costs of operation is estimated by identifying both fixed and variable (flow dependent)costs and applying an adjustment factor to both future fixed and variable costs based on historical data.

In Fiscal Year 2013 2014 (7/1/13 6/30/14), the WWTP incurred a total operational cost of $389,758,broken down as shown on the following page:


of 58

Fixed Cost Variable (Flow Dependent) Cost

Departmental Supplies $40,056.00 Plant Chemicals $32,529.00Testing/Monitoring $41,799.00 Utilities $64,676.00Contracted Services $124,393.00 Sludge Disposal $16,770.00Plant Maintenance $42,896.00 Equipment Repair $8,220.00 Insurance $4,262.00 Misc $14,157.00

Total Fixed Cost $275,783.00 Total Variable Cost $113,975.00

Total Operational Cost for FY 2013 2014: $389,758.00

During this same time period, the WWTP treated a total of 196,235,000 gallons, which represented avariable cost of $581 per MG treated (a summary of these calculations can be found in the “SupportingDocuments” section of this report). If a future inflation rate of 2% per year is assumed for all costs, thenfuture total cost of operation for future years can be estimated as follows:

Cost/Year1 = $275,783(1.02) + ($581)(Volume Treated, MG)(1.02)

The WWTP includes two parallel process streams (aeration basin and secondary clarifier), each with acapacity of 1.5 MGD. Current operation at a flow rate of 0.6 MGD allows for the operation of only one ofthe process streams with no flow equalization. As flows increase above 1.5 MGD, the second processstream will need to be placed into operation (the flow rate in which this occurs is operational dependent),and flow equalization may be needed intermittently. Placing the second process stream on line, as well asoperating the aerators in the equalization basin will result in a step increase in the variable cost. Theestimated step increase that will result when one or both processes are placed on line is included in theannual adjustment factor.

Estimated Cost of Treatment as a Function of Flow Rate in 2015 Dollars for Various Flows

Average Annual Flow Annual Cost

1.0 $ 487,7781.5 $ 593,7762.0 $ 699,773

Note that since fixed costs account for over 71% of historical total costs, the marginal cost of operation(cost per MG treated ) will decline as flows increase.


of 58

CONCLUSIONS AND RECOMMENDATIONSThe WWTP is currently well operated and maintained, meeting all effluent limits regularly at an averageflow rate of less than 25% of the rated capacity. However, many items of process equipment are off lineand have not been operated since the last expansion in 2006. In order for the plant to successfully treatflows in excess of 1.0 MGD up to 3.0MGD, it is recommended the Town implement the followingimprovements and operational modifications:

Current Flow to 1 million gallons per day

1. Repair concrete and re level effluent weirs in both secondary clarifiers.2. Place Clarifier #2 in operation and implement a standard operating procedure to exercise it

periodically when not in use.3. Install secure fencing around all ground level process units.4. Rebuild both clarifier drive units and scrapers5. Replace generator as budgeted in the CIP.

Items to be Completed Prior to Exceeding Flows of 1.0 MGD:

1. Repair liner in Aeration Basin #2 as budgeted in the CIP.2. Upgrade and/or replace undersized influent screen.3. Purchase and install four (4) 25 HP floating aerators in Aeration Basin #2.4. Place all equalization basin aerators in operation and implement a standard operating

procedure to exercise all process equipment periodically when not in use.5. Install plant wide SCADA system to provide continuous monitoring of operations critical

equipment as budgeted in the CIP.6. Replace generator as budgeted in the CIP.

Items to be Completed Prior to Exceeding Flows of 2.0 MGD:

1. Repair equalization basin by pass valve.2. Install an adjustable by pass weir at the equalization basin – aeration basin splitter box.

A list of all recommended capital improvements and their associated cost are shown in Table 3.


of 58

Table 3: Capital Expense Per Flow Threshold

To Be Completed Prior to 1.0 MGD Flow

1 Repair concrete and re level effluent weirs in both secondary clarifiers. $10,000.002 Install secure fencing around all ground level process units. $15,000.003 Rebuild both clarifier drive units and strainers $20,000.004 Replace existing 500kVa Generator $175,000.00

Total Capital Expense Prior to Exceeding 1.0 MGD Flow $220,000.00

To Be Completed Prior to 1.5 MGD Flow1 Repair liner in Aeration Basin #2. $39,000.002 Upgrade and/or replace undersized influent screen. $100,000.003 Purchase and install four (4) 25 HP floating aerators in Aeration Basin #2. $25,000.004 Replace six (6) 10Hp floating aerators in Equalization Basin $75,000.00

5 Install plant wide SCADA system to provide continuous monitoring of operationscritical equipment. $115,000.00


To Be Completed Prior to 2.0 MGD Flow1 Repair equalization basin by pass valve. $10,000.00

2 Install an adjustable by pass weir at the equalization basin – aeration basinsplitter box. $25,000.00



of 58

LIST OF FIGURES

Figure 1. Influent Bar Screen is highly corroded and need of immediate replacement.

Figure 2. Influent Microstrainer is undersized and needs to be either replaced or upgraded to accommodatehigher flow rates.


of 58

Figure 3. Equalization Basin is currently not in operation. Current flows have not required it to be used,however, the Basin will need to be utilized once peak wet weather flows approach 2.0 MGD.

Figure 4. None of the 10 Hp floating aerators are operated on a regular basis. Only six of the ten units werereported to be operational as of May, 2015.


of 58

Figure 5. The valve for the Equalization Basin by pass structure is not operational and must be repaired beforethe Basin can be placed on line.

Figure 6. Aeration Basin #1 has six – 25 Hp floating aerators, despite being at least ten years old, all appear to bein good to fair working order based on electrical tests conducted in May of 2015.


of 58

Figure 7. The two – 25 Hp floating aerators in Aeration Basin #2 are operational despite their age. Fouradditional aerators must be installed to allow for full operation of this basin.

Figure 8. Aeration Basin #2 liner is damaged and must be repaired or replaced before being placed intooperation.


of 58

Figure 9. Secondary Clarifier #2 is currently offline and has not been operated in years. The unit will need to bedrained and fully inspected before being placed back on line.

Figure 10. Effluent weirs and concrete trough in Clarifier #1 are uneven and in poor condition.


of 58

Figure 11. Aerobic Digester is in good condition – small leaks in the supertatant draw off line should berepaired.


of 58

SUPPORTING DOCUMENTS


of 58

OPERATIONAL COST PROJECTIONSThe following page contains the spreadsheet results for the projected operational Costs based on flow in millions ofgallons (MG)


of 58

WWTP Operational Cost Projection (2013 Dollars)

Annual Fixed Costs

Departmental Supplies $40,056.00 Flow (MG) Cost

Testing/Monitoring $41,799.00 0.6 $402,980.11Contracted Services $124,393.00 0.8 $445,379.15Plant Maintenance $42,896.00 1.0 $487,778.18Equipment Repair $8,220.00 1.2 $530,177.22Insurance $4,262.00 1.4 $572,576.26Misc $14,157.00 1.6 $614,975.29Total Fixed $275,783.00 1.8 $657,374.33

Annual Variable Costs 2.0 $699,773.37

Plant Chemicals $32,529.00 2.2 $742,172.41Utilities $64,676.00 2.4 $784,571.44Sludge Disposal $16,770.00 2.6 $826,970.48Total Variable Costs $113,975.00 2.8 $869,369.52

3.0 $911,768.55

Flow Treated in 2013 2014 196,235,000

Annual Fixed Cost $275,783.00 Annual Variable Cost $113,975.00 Variable Cost/MG $580.81


of 58

MECHANICAL COMPONENT TESTINGThe following three pages contain results submitted by Camp Electric after testing amperage draw on various piecesof equipment. The first two pages contain location information for each component that references the test resultson the third page.


of 58


of 58

AERATION BASIN #132.1 31.1 31.3 amps.30.8 31.0 29.1 amps.31.1 31.2 31.1 amps.31.5 31.0 30.3 amps.32.0 30.5 28.0 amps.31.7 31.8 32.0 amps.

AERATION BASIN #231.0 31.2 31.4 amps.30.2 30.0 30.3 amps.

EQ BASIN STAND APower to stand good but nothing coming on15.4 15.4 15.0 amp.No wiring going outPower on to stand but no motor coming on

EQ BASIN STAND B15.3 15.5 15.4 amps.15.4 15.4 15.1 amps.Power to stand but nothing coming on16.4 16.2 15.9 amps.Wires broke at waters edge

EQ BASIN STAND C15.8 15.7 15.4 amps.15.7 15.6 15.3 amps.16.0 16.0 15.4 amps. Making bad noiseUsed for caustic tank


of 58

WWTPBUDGET INFORMATIONThe following two pages contain budget information for the wastewater treatment plant operation.


of 58


of 58

Town of Rutherfordton


of 58

RUTHERFORDTONNPDES PERMIT


of 58


of 58

RUTHERFORDTON LAND APPLICATION PERMIT


of 58


of 58

Rutherfordton WWTP Capital Needs Review 7-21-15 · Rutherfordton WWTP Capital Needs Report, July...

Documents

Transcript of Rutherfordton WWTP Capital Needs Review 7-21-15 · Rutherfordton WWTP Capital Needs Report, July...