138

TECHNICAL MEMORANDUM

CONCEPTUAL DESIGN

AIR STRIPPING SYSTEMEAU CLAIRE MUNICIPAL WELL FIELD

MAY 20, 1 9 8 5

CONTENTS

IntroductionSite DescriptionSummary of the Selected Initial Remedial MeasuresRationale for SelectionDescription of the IRMDesign Criteria SummaryPreliminary LayoutsOperation and Maintenance Requirements

OperationMaintenanceMonitoringDesign and Implementation ConsiderationsTe chnicai-€eft»i4erat ions'acility Sitin^COnfTIctsUpgrade North Well Field WellConstant Speed Versus Adjustable Speed PumpingBlower Turndown'acking—Goaf igiu aAdditional Engineering DataPilot Data and InterpretationSoils InformationSite Survey

Costs Estimates and SchedulesCost EstimatesImplementation Schedule

GLT497/56

INTRODUCTIONThis conceptual design has been prepared for the selectedInitial Remedial Measure (IRM) that is proposed for the EauClaire Municipal Well Field. The conceptual design developsthe selected IRM in more detail than presented in the FocusedFeasibility Study (FFS) and will serve as the foundation forthe final engineering design of the IRM. This technicalmemorandum, which presents the conceptual design, consistsof four sections as follows:

o Site Descriptiono Summary of the Selected Initial Remedial Measureo Design and Implementation Considerationso Cost Estimates and Schedules

A description of the Eau Claire Municipal Well Field and theEau Claire Water Treatment plant is presented under SiteDescription. In addition, a brief history of the problem ispresented to establish a framework within which the IRM mustperform.A technical description of the selected IRM is outlined inthe Summary of the Selected Initial Remedial Measure. Pre-liminary design criteria and rationale are identified andthree preliminary drawings are presented. These drawingsconsist of a site layout, a process flow diagram, and a faci-lity layout.In the third section, Design and Implementation Considerations,unresolved concerns and design considerations are highlighted.These issues will be evaluated and resolved in the finalengineering design of the IRM.The final section of this memorandum presents cost estimatesand implementation schedules for the IRM.

SITE DESCRIPTIONThe City of Eau Claire is a community of approximately 5 5 , 0 0 0population located in west-central Wisconsin. The City'swater system, as well as that of the Town of Washington (appro-ximately 2 , 5 0 0 residents), are supplied by groundwater producedby the Eau Claire Municipal Well Field. Low levels of volatileorganic compounds (VOC' s ) have been found in the Eau Clairemunicipal water supply system.The City of Eau Claire and WDNR have monitored VOC concentra-tions closely since their discovery in 198 1 . Thus far theCity has been able to provide a safe potable water supply tothe community by blending water furnished by the contaminatedwells with water from the slightly contaminated and cleanwells. The DNR nominated the Eau Claire Municipal Well Field

as a potential Superfund site in spring of 1983 . Subsequently,in September of 1 9 8 4 , the site was placed on EPA's NationalPriority List making it eligible for federal funds.The municipal well field is a 500-acre site located in thenorthwest corner of the City on the east bank of the ChippewaRiver. A water treatment facility is located at the southernend of the field. There are 14 active wells in the wellfield, with 9 wells developed in the north well field, and 5wells in the south well field. Historically, the north wellfield has exhibited lower iron and manganese concentrationsthan water from the south well field, therefore, the Cityhas always considered the north well field to produce thehighest quality raw water. However, the highest levels ofVOC concentration have been observed in the north well field,particularly in Well Nos. 11, 15, 16, and 17.The existing raw water treatment plant has a design capacityof 24 mgd and consists of hardness removal, followed by fil-tration, disinfection and fluoridation. Current operationentails split flow treatment with only water produced by thesouth well field being subjected to hardness removal. Waterfurnished from the north well field is blended with the watertreated for hardness removal from the south well field immedi-ately prior to filtration.A more detailed site description and more thorough backgroundhave been previously presented in the Focused FeasibilityStudy, dated April 11, 1985 . Copies of this document areavailable upon request.

SUMMARY OF THE SELECTED INITIAL REMEDIAL MEASURERATIONALE FOR SELECTIONThree alternatives were developed and evaluated in the FFS.Based on comparing the three potential initial remedial mea-sures with the evaluation criteria established, a packedtower aeration system capable of stripping VOC's from a flowof 14 mgd was recommended as the preferred alternative. Theprimary factor leading to the selection of this alternativewas its ability to more reliably protect public health thanthe other alternatives under consideration. Both of the twoother alternatives depended on the performance of a blockingwell barrier to block the flow of contaminated groundwaterfrom entering the municipal well field. The level of confi-dence of the design of a blocking well barrier is more uncer-tain than that associated with an air stripping system. Asa result, the air stripping system was judged to providemore reliable protection of public health.All three alternatives compared consistently with respect tothe other evaluation criteria used in the FFS. No

outstanding differences were observed in the areas of relativecosts, environmental effects, and time required to implement.DESCRIPTION OF THE IRMThe selected IRM will consist of an air stripping systemcapable of removing VOC's from a flow of 14 mgd furnished bythe north well field. The air stripping system will consistof three packed stripping towers, each 12-feet in diameterwith 30 feet of packed bed depth and ancillary componentsnecessary to make the system complete. Figure 1 presents aPreliminary Process Flow Diagram of the selected IRM.Raw water will be delivered to the air stripping treatmentfacility from any of the nine active wells in the north wellfield. Since water delivered from the north well field haslimited available head when it reaches the treatment plant,pumping to the air stripping towers will be necessary. Three(3) in line, adjustable speed pumps will be provided to pumpthe raw water over the tower. The pumps will be sized suchthat two pumps deliver the design flow and the third pumpwill serve as a standby. The pumps will discharge to a commondistribution header equipped with three laterals; one foreach tower. Each lateral will be furnished with a flowmeterand balancing valve to allow for approximately equal distribu-tion of the flow between the three towers.The three towers will be operated in parallel. The prelimi-nary configuration of the towers is illustrated in Figure 1.Each tower will consist of two 15-foot deep packed beds.The advisable stacking depth of the packing is limited toavoid deformation of the media which would result in poortransfer efficiencies and more frequent plugging problems.A second support plate and an intermediate distributionplate will require about a 4-foot separation between the twobeds. Sizing of the plenum and sump and the tower stackduring final design will determine the overall height of thecolumns. Based on preliminary sizing criteria and facilitylayouts, the overall height of the columns will be approxi-mately 55 to 60 feet above the existing ground surface.The structural shell of the columns will be fabricated offiberglass reinforced plastic (FRP) . The packing media willbe an acid resistant plastic and the column internals ( i . e . ,distribution plates, packing restrainers, and support plates,etc.) will be stainless steel.Each tower will be equipped with an air supply fan capableof delivering sufficient air to maintain the required air towater ratios. The fans will be equipped with inlet silencersto reduce ambient noise levels.

W6U. CUT*

K.OW*f£7-E&S4£_ ACyA*S&*-*£

~T >K£i.^. <?

/BW M«7T5?BOOSTER PUMPS

•H*

/^--^•H+l Kl V _

J*J-£Xj-

>*AO<-7^ /=7---3

717 &KAIN\

6 tx>

JJV/Vtf? tf /^/Atf*

If it.t *HH* r r *T

JLJUUUUUUUUUL

-t-OtVEK f&CXING

-La**&?f*eK//*sst/W'asrr-N /**£&*?£*

MerrS*

•**&M\ /*r-z

sxatf\ rr- 2 f?XM<\ f^T-3

@3— -fsj—(4

V

M£tfr PLANT

WELLPfSCHAKGE POWNSTKEAMOf= CONNECTiOM-

O^ DOCUMEMTVTM3 OOCUMerT. AM) THE «CAS ANO OCStONS MCOA-

AS AN MCTMUMetT Of PftOFCSSKMALUSB). M WHOLE Off M PAffT. KMWMTMOUT TVC WMTTB4 AUtHOmlATION 0* CMM MU.

BAHtSCMEMCMON

EAUCONCEPTUAL DESIGN

MUNICIPAL WELL FIELDFIGURE 1

PRELIMINARY PROCESS FLOW DIAGRAM

SMCET 1of3

DAT* MAY 1905

A chlorination system will be provided for each tower toperiodically recycle a chlorine solution through the towersto clean and disinfect the packing. The chlorination systemwill be designed to allow acid washing of the packing mediashould iron buildup and scaling be exhibited.Locating the base of the stripping tower at grade on thetreatment plant site will require repumping the treated waterto the existing treatment system. Raw water which has beentreated by the air stripper will flow by gravity into a wetwell. Three (3) adjustable speed pumps will be provided topump the raw water into the existing treatment plant. Thepumps will be designed such that two pumps are capable ofdelivering the design flow while the third will serve as astandby.A mechanical building will be constructed to shelter thepumps, electrical controls, chlorination system, and ancillarysystem components. The building will consist of a concretemasonry block building with a steel joist and metal deckroof.To provide system flexibility, a bypass around the air strip-ping system will be installed. The frequency of use of thebypass is expected to be minimal since preferential pumpingof the four production wells with the highest levels of conta-mination is recommended to assist in limiting the spread ofcontamination. The bypass valve will normally be locked inthe closed position and only a limited number of key staffwill be provided with access keys.DESIGN CRITERIA SUMMARYThe stripping system will be designed to provide air strippingfor a maximum hydraulic loading of 14 mgd from the northwell field. The design flow was established on the followingbasis. Historical data has shown that the maximum dailydemand over the recent record has been approximately 20 mgd.A safety factor of 10 percent was added to the historicalmaximum daily demand to establish 22 mgd as the maximum dailydesign flow which the municipal system should .furnish. Thesouth well field is capable of furnishings mgd~~^f safe watertoward meeting the design flow of 22 mgd. The "remaining14 mgd must be furnished by the north well field. Currently,only 8.6 mgd of the total production capacity of the northwell field is significantly contaminated. However, sincehalting the spread of the contamination cannot be assumed,the IRM must be sized to provide air stripping for the balanceof the water needed to meet the maximum daily demand. There-fore, maximum daily demand (22 mgd) less the raw water sup-plied by the south well field (8 mgd) equals the air stripp-ing system design capacity of 14 mgd.

The groundwater contaminants observed in the raw water pro-duced by the well field are identified below in Table 1.The design basis for the air stripping system establishesremoval efficiencies for these compounds such that the fin-ished water provided to consumers will contain VOC concentra-tions equal to or less than 1 x 10 excess lifetime cancerrisk. The estimated future maximum concentrations of thesecompounds as well as the corresponding minimum removal effi-ciencies are also presented.Design criteria for the major components of the air strippingsystem are identified in Table 2.PRELIMINARY LAYOUTSFigure 2 presents a preliminary site layout for the IRM.The air stripping towers and associated mechanical buildingwill occupy an area of approximately 4 , 2 0 0 sf immediatelyoff the northeast corner of the existing settling basins.The stripping towers will be located in a linear patternalong a north-south line with the building located contiguousto and west of the towers. The connection to the 36-inchdischarge pipe from the north well field will be made approxi-mately 230-feet north of the existing treatment facility.Locating the connection at this point will reserve the adja-cent corridor for future expansion of the treatment plantand avoid potential interferences with Well No. 18 dischargepiping. Treated water from the air stripping system will bedischarged into the existing influent box at the head end ofthe settling basins.Approximately 350 feet east of the proposed site for thestripping facility is the foot of a steep bluff. The bluffrises nearly 80 feet at a slope of 1 to 1. A number of resi-dences are located at the top of the bluff. This is an impor-tant aesthetic consideration and factors such as tower heightand noise levels must be addressed in the final design process,Figure 3 presents a preliminary layout of the air strippingfacility. Raw water will be delivered to the facility via anew 36-inch pipe connected to the existing well dischargepipe. Three adjustable speed, in line, vertically mountedsplit casing centrifugal pumps will be used to boost thewater over the stripping towers. Two pumps will be capableof boosting the design flow of 14 mgd, the third pump willserve as a redundant unit. For purposes of the conceptualdesign, it has been assumed that variable frequency driveswill be used to provide the speed adjustment on the boosterpumps. Control of the variable frequency drives will belinked to pressure sensing on the suction side of the pumps.Raw water will be distributed evenly between the three stripp-ing towers using a distribution header, flow meters, and

a

0

!

so/

^V~" 1 EXISTING PIPING LOCATIONS WHICH INFLUENCE LAYOUT OF THEINITIAL REMEDIAL MEASURE MUST BE VERIFIED BY FIELD SURVEY.

} EXISTING WELL FIELD AND TREATMENT PLANT PIPING NETWORKCONFIGURATION MUST BE UPDATED AFTER FIELD SURVEY.

REUSE OP DOCUMENTSIVbM^ta » • *^*»^***«B>^r» I +f I—————————THHS DOCUMENT. ANO THE IDEAS ANO DESIGNS INCOR- I a*" « ONE INCH ONPORATED HEREIN AS AN INSTRUMENT OF PROFESSIONAL I OBIGINALDRAWING.USED. IN WHOLE OR IN *ABT. FOR ANY OTHER «WXIECT I IF NOT ONE INCH ONWITHOUT THE WRITTEN AUTHORIZATION O* CHZM MILL I j G SHEET, ADJUST

CONCEPTUAL DESIGNEAU CLAIRE MUNICIPAL WELL FIELD

FIGURE 2PRELIMINARY SITE LAYOUT

SHEET 2of3

DATE MAY 1985

RACKED TOWERCm* OF 3)

PACK5P TOWEREFFLUENT (TYF)

PACKED TOWER0KAIN SUMP (TYF)

J»———P&INFECTIONPKA/N L/NE (TYf)

MO7VR CONTROL. CENTERPROPELLERFLOW METER(TYP OPS)

PUMP £ SUMP

FLOOR PRA/N (TYP)

CONCRETE SLAB

INFLUENT

(I

INFLUENTBOOSTER PUMP(TYP OF3J

FLEXIBLE COUPLING (TYP)8YPAS5

PACKEP TOWEREFFLUENTWET WELL

EFFL UENT PUMP(TYP OP 3)'

•WELL ACCESS HATCH

-CONCRETE MASONRYSUILDtNG

EFFLUENT TO EX/STfMSTREATMENT FACILITY

PLAN

OSGHRJ.SCHLtCHER REUSE OF DOCUMENTSTHIS DOCUMENT. ANO THE IDEAS ANO DESIGNS INCOR-PORATED HEREIN. AS AN INSTRUMENT OF PROFESSION*!.SERVICE, a THE PftOMPTY Of CKIM HIU. ANO IS NOT TO MUSED. IN WHOLE OH * *A«T. TOR ANY OTHER PROJECTWITHOUT THE WRTTTW AUTHORIZATION Of OOM HHJ.

BAfl IS ONE tNCM ONOFVGMAL ORAIMNO.

IF NOT ONE INCH ONTHB SHEET, ADJUSTSCALES ACCOPOWGLH

CONCEPTUAL DESIGNEAU CLAIRE MUNICIPAL WELL FIELD

RGURE 3PRELIMINARY LAYOUT OFAIR STRIPPING FACILITY

SHEET 3of3

DATE MAY 1985

throttling valves as indicated in Figure 3 and in the processflow diagram. The system will be designed such that threetowers will be operational the majority of the time, thusminimizing the number of startup efforts for towers takenout of service. The north well field has typically furnishedbetween 6 and 7 mgd of the average daily demand of 9 to 10 mgd.The air stripping system will be designed to operate effectivelyusing three towers for flows ranging from 5 to 14 mgd. Atflows below 5 mgd, it may be necessary to take one tower outof service.As previously stated, the air stripping towers are sized toprovide the required removal ( i . e . , 9 9 . 6 percent) of thecritical contaminant, 1,1-dichloroethene. Thirty feet ofpacked media depth is necessary to provide adequate opportun-ity for transfer of the VOC' s . The preliminary design hasbeen developed assuming two 15-foot deep packed beds pertower, with a 4-foot separation between beds. Recent discus-sions with packing suppliers have indicated a single bed,30-feet deep, may be possible, thus eliminating the need forthe 4-foot separation and decreasing the overall height ofthe tower. This issue will be addressed and resolved duringfinal design.Each tower will be equipped with a sump and blower. Thesump is sized based on two criteria. First, the sump mustcontain an adequate volume of water to allow for continuousflushing of the packing with a chlorine solution, accountingfor the "holdup" of flushing water by the packing. Second,the sump must be adequately sized to allow uniform distribu-tion of air supplied by the blower across the bottom face ofthe packing. The blower wilx be designed to supply a 56to 1, air to water ratio at design flow. Since the systemwill not always be operated at design flow, the blowers willbe equipped with a some turn down capabilities to reduceoperating costs. As noted in the discussion of the siteplan, the stripping system must be located in close proximityto several private residences. As a result, inlet silencersfor the supply fans will be necessary.From the tower sumps, water will flow by gravity into a wetwell and then be pumped to the head end of the existing treat-ment facility. Three adjustable speed, vertical turbinepumps will be used to pump the water treated by the air stripp-ing system into the conventional water treatment facility.The pumps will be sized such that two pumps will handle thedesign flow while the third pump will be in standby. Variablefrequency drives will be used to achieve the adjustable speedfeature. Control of these drives will be linked to levelsensing in the wet well.

OPERATING AND MAINTENANCE REQUIREMENTSOperationContinuous pumping of the contaminated wells through the airstripping system is recommended. This procedure will helpcontrol migration of the contaminant plume and limit thespread of contamination. Continuous operation of all threestripping towers is also preferred to prevent problems associ-ated with on and off operation such as biological growth,freezing, etc. Pumps and blowers will be equipped with someturndown capability to minimize costs of operating the system.MaintenanceThe maintenance requirements of the air stripping systeminclude equipment maintenance and packing media maintenance.Equipment maintenance involves routine procedures typicalwith mechanical equipment, such as greasing blower bearings,and is estimated to require approximately 16 man hours permonth.Maintenance of the packing media is necessary to preventbiological growth or deposition of minerals. Initially, andafter each shutdown period, the towers will be disinfectedwith a chlorine solution ( 0 . 0 3 percent) for approximately2 hours followed by a 1-hour rinse cycle. In addition, thisprocedure will be performed on each tower once every threemonths unless actual operating conditions demand otherwise.If mineral deposition on the media becomes a problem, anacid wash similar to uhe disinfection will be employed.MonitoringThe monitoring requirements for the selected IRM are:

o Monitoring of the test wells and production wellso Monitoring the stripping towers influent and efflu-

entCity personnel currently collect and analyze samples fromthe test wells and production wells on a monthly basis.This procedure should be continued to provide valuable infor-mation on contaminant plume migration and any change in conta-minant concentrations which would affect the stripping system.Monitoring the stripping towers efficiencies is necessary toassure proper operation and sufficient removal of contaminantsFour samples (one common influent and three effluent) willbe collected and analyzed for VOC' s on a regular basis. TheWisconsin Department of Natural Resources requires the follow-ing sample frequency:

1st week after each startup - I/day2nd thru 12th week after each startup - I/week13th week on - 1/month

DESIGN AND IMPLEMENTATION CONSIDERATIONSWith the completion of the conceptual design effort and theprevious focused feasibility study, a number of unresolvedissues relating to the design and implementation of the airstripping system have emerged. These issues, which are mostappropriately resolved during the final design activities,are briefly discussed below. In addition to the typicaldesign activities scoped into the work plan for the finaldesign, these specific issues will be identified in the workplan to ensure they are addressed.TECHNICAL CONSIDERATIONSFacility Siting ConflictsThe location of the air stripping facility on the water treat-ment plant site (as shown in Figure 2) appears to be themost desirable from a facility layout and operation viewpointThe facility would be close to the head end of the watertreatment plant and would enable relative ease of observationand operation of the air stripping system. However, theresidences on top of the steep bluff located immediatelyeast of the proposed location, present a potential conflict.The full impact of the plumes being emitted by the strippingtowers must be evaluated before the proposed site can beconfirmed. During final design a study of prevailing windpattern and other significant meteorological data, as wellas an effort to model plume dissipation will be necessary.This evaluation will address the toxicity effects of theplume ( i . e . , estimate VOC concentrations in the atmospherenear the residences) , potential for odors cause by the airemissions, and the impact of the saturated air discharge atcolder temperatures ( i . e . , the potential for fogging andicing problems at the ground surface) . Should any of theseconcerns present serious problems a potential secondarysiting choice would be west of the existing treatment plantcomplex — in the area of the "Operator's House" shown inFigure 2. Relocating the facility and adjusting the stackheight provide the flexibility needed to mitigate anyproblems created by the air discharge plume.Upgrade North Well Field Well PumpsTo minimize the height of the tower above the ground surfaceand limit tower construction costs, pumping of the raw waterbefore and after the tower will be necessary. The 9 activewells in the north well field deliver raw water to the treat-ment plant with limited excess available head. Two optionsexist for furnishing the necessary head to lift the raw water

over the packed tower. As presented in this conceptual design,a battery of in line booster pumps may be used. This optionis technically feasible and represents a conservative concep-tual design approach. A second option that exists is toupgrade the existing well field pumps by adding additionalstages and larger motors, if required, to deliver the designflow to the plant with sufficient head to discharge over thepacked towers. Depending on the current condition of thewell field pumps and well field electrical provisions, thisoption may be less costly than the in line pumping option.Constant Speed Versus Adjustable Speed PumpingAdjustable speed pumps using variable frequency drives havebeen assumed necessary for both tower influent and towereffluent pumps. Again, this is a conservative conceptualdesign approach. The potential exists that both sets ofpumps may be able to function as constant speed pumps. Finaldesign activities should evaluate the use of constant speedpumps and compare the cost trade-offs in both pumping applica-tions.Blower TurndownMinimizing operating costs associated with the air strippingsystem is an important concern of both the City of Eau Claireand Wisconsin DNR. Since the stripping tower will not operatecontinuously at design capacity, some turndown capability inthe blowers, proportional to raw water flow turndown, wouldbe desirable. Use of inlet guide vanes or variable speeddrives on the blowers will be investigated to minimize bloweroperating costs.Packing ConfigurationThe conceptual design has assumed that each tower will con-sist of two packed beds each 15-feet deep with a 4-foot inter-mediate separation. With some types of packing media theintermediate separation may be eliminated, thus decreasingthe overall tower height. The final design effort will evalu-ate the feasibility and effectiveness of a single bed approxi-mately 30-feet deep for each tower.ADDITIONAL ENGINEERING DATAPilot Data and InterpretationThe City of Eau Claire, with the assistance of Strand andAssociates, had conducted pilot testing of the air strippingprocess in late 1 9 8 4 . Securing a copy of the raw data andthe report presenting the interpretation of that data isdesirable to optimize the final tower design. VOC removalperformance data contained in the pilot data may prove the

preliminary tower design to be conservative and allow somereduction in tower size.Soils InformationSoils information near the proposed site of the facilityappears to be limited to data pertaining to the constructionof Well No. 18. A maximum of 3 to 5 borings at the proposedlocation of the stripping towers and building are necessary.This information will assist in defining foundation designcriteria and potential construction difficulties related tosubsurface conditions.Site SurveyA detailed site survey in the area of the proposed construc-tion will be necessary to locate interface piping and avoidsiting conflicts. The existing water treatment plant andwell field piping system have been constructed over manyyears and through numerous construction contracts. In-housemodifications to optimize system operations have also occurredAlthough general records of the construction are available,consistency between records is not exhibited and the levelof confidence of future siting based on these records isuncertain. A field survey of several identified interfaceswill result in a reliable layout of the air stripping system.

COST ESTIMATES AND SCHEDULESCOST ESTIMATESTable 3 presents an order-of-magnitude cost estimate for theselected IRM. (The American Association of Cost Engineersdefines this classification of estimate as having an expectedaccuracy of +50 percent and -30 percent). The total costdeveloped in this phase of the project are somewhat higherthan those estimated in the FFS. The increased costs arethe result of additional requirements disclosed during theconceptual design, such as:

o The requirement for tower effluent pumps in additionto the booster pumps

o The enlargement of the mechanical building to housethe additional pumps

o Additional electric equipment to provide power tothe stripping system for the supply available atthe existing treatment plant.

Costs for equipment and major material component costs ( i .e . ,pumps, blowers, towers, packing, and tower internals) werederived through conversations/quotations with suppliers and

10

manufacturers. Estimated costs include delivery and installa-tion. The building costs includes an insulated, heated andventilated concrete masonry block building. Structural costswere based on costs for similar work in the upper midwest.Construction excavation costs were based on local rates.The estimated annual operation and maintenance costs areshown in Table 4. Annual electrical costs are estimatedbased on continuous operation at average flow conditions(9 mgd) and 1-day per month operation of the disinfectionsystem. Power costs were assumed to be $ 0 . 0 5 per kWh. Equip-ment maintenance costs were based on a labor rate of $ 1 8 . 8 0per hour (including benefits). Cost for maintenance materialsand supplies were based on 2.5 percent of the installed costper year.Washdown costs were estimated assuming 8 manhours per monthat $ 1 8 . 8 0 per hour and approximately $500 per year in chemi-cal costs. Monitoring costs were based on the required samplefrequency and analytical costs (including labor) from theCity of Eau Claire's Public Utility Services personnel.IMPLEMENTATION SCHEDULEFigure 4 presents the preliminary implementation schedulefor the IRM. Assuming final design can begin approximatelyJune 1, 1 9 8 5 , the facility could be in operation in earlyDecember. The schedule assumes CH2M HILL would function asthe construction manager and prepurchase the equipment andmanage the construction contract. The proposed and acceler-ated delivery process shortens the overall schedule by 3 to4 months from typical delivery approaches which require thegeneral contractor to furnish all equipment. This approachexhibits the potential for cost savings in the area of equip-ment procurement and completion of construction prior toadverse winter weather conditions.GLT497/ 105

11

Table 1VOC REMOVAL DESIGN CRITERIAESTIMATED FUTURE MAXIMUM

Influent MinimumcConcentration Removal EfficiencyCompound (ug/L)

1,1-dichloroethene* 25 99.6

Trichloroethene 43.3 99 .3

Tetracnloroethene 21.4 99.1b1,1,1-trichloroethane 235

v bV_- 1,1-dichloroethane 12.9

The critical contaminant is 1,1-dichloroethene. Removal efficiencies for the othercarcinogens are based on 99,6 percent removal of 1,1-dichloroethene.These compounds do not have cancer potency values.cEstimated future maximum concentrations.

GLT497/107

Table 2 (Page 1 of 2)COMPONENT DESIGN CRITERIA

Packed TowerNumber of TowersShell DiameterCylindrical Shell Height1:1 Cone HeightStack HeightStack DiameterMedia HeightShell MaterialNumber of Media Support PlatesLiquid Flow Rate per TowerLiquid Loading RateHeadlessAir/Water RatioLiquid TemperatureAir Temperature

312 ft51 ft

4.5 ft9 ft4 ft

30 ftFRP2

3,500 gpm30 gpm/ft2

0.25 in H 0/ft of packing56

50°F average, 46° minimum-15°F to 100°F

Packed Tower Media

MaterialTypeSizeVolume per Tower

PlasticPall Rings2 inches3,400 ft*

Supply Blowers

TypeNumberFlowrate/TowerStatic PressureFan SpeedMotor Horsepower

Centrifugal Airfoil3 (1 per tower)

26,000 scfro8 Inches1,400 rpm

50

Tower Influent Booster PumpsTypeNumberCapacity/PumpPumpMotor Horsepower

Split Casing Centrifugal3

5,000 gpm @ 40 ft XDH (maximum)Adjustable; 880 rpm max

60

Table 2 (Page 2 of 2)

Tower Effluent Pumps

TypeNumberCapacity/PumpSpeedMotor HorsepowerWet Well Volume

Vertical Turbine3

5,000 gpm @ 40 ft TDH (maximum)Adjustable; 1,160 rpro max

7521,000 gal

Chlorlnation System

Liquid Loading RateDisinfection FrequencyPump TypePump CapacityPump SpeedMotor HorsepowerSump Volume

3 gpra/ft2Once per 3 months-minimum

Fiberglass wet-pit400 gpm @ SO ft TDH

1,750 rpm20

3,300 gal

GLT497/108

Table 3CAPITAL COST ESTIMATE

Yard Piping/Site Work $ 8 5 , 3 0 0Tower Foundation 57 , 100Mechanical Building 8 2 , 6 0 0Process Piping/Valves 9 9 , 9 0 0Major Equipment

Packed Towers 4 3 2 , 0 0 0Blower/Silencer/Ductwork 46, 100Booster Pumps /Variable Frequency Drives 1 3 5 , 2 0 0Effluent Pumps/Variable Frequency Drives 1 10 ,900

Electrical/HVAC/Pumping 1 5 1 , 1 0 0Construction Subtotal 1 , 2 0 0 , 0 0 0Construction Contingency (20 percent) ' 2 4 0 , 0 0 0Construction Total 1 , 4 4 0 , 0 0 0Construction Engineering (5 percent) 7 2 , 0 0 0 -Total Implementation Cost 1 , 5 1 2 , 0 0 0Engineering Design Costs (8 percent)^ 1 1 5 , 0 0 0Total Implementation Cost Plus Engineering ,

Cost l , 6 2 7 , O O O a ' D

Order-of-Magnitude estimate; expected accuracy +50 to -30.percent.DENR CCI 4200GLT497/59

Table 4ESTIMATED ANNUAL O&M COST

Monitoring $ 2 , 0 0 0Disinfection Washdown 2 ,500Equipment Maintenance 8 , 0 0 0Electric Power 1 0 8 , 0 0 0

TOTAL $ 1 2 0 , 5 0 0

GLT497/ 109

FINAL DESIGN

EQUIPMENT PREPURCHASE

CONTRACTOR PROCUREMENT

CONSTRUCTION

OPERATION

1986

MAY6 113 201 27

JUNE3 10 17 24 30

JULY AUG7 14 21 |28 4 11 IB | 25

SEPT1 8 16 22 129

OCT6 13 120 27

NOV3 10 17 24

DEC1 | 8 16 22 29

FIGURE 4EAU CLAIRE MUNICIPAL WELL FIELDIRM IMPLEMENTATION SCHEDULE