RECORD OF DECISION FOR THE LEE CHEMICAL SITE · Water Supply Wells Number 1 through 7 (WSW1 through...

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MEMORANDUM

SUBJECT:

FROM:

TO:

Record of Decision for the Lee Chemical Site

David A. WagonerDirectorWaste Management Division

Morris KayRegional Administrator

40175476

SUPERFUND RECORDS

Attached for your signature is the Record of Decision (ROD)for the Lee Chemical Site which is located in Liberty, Missouri.The Missouri Department of Natural Resources (MDNR) is the leadAgency for the remedial actions at the site, and the State ofMissouri concurs with the selected remedy as described in theROD.

This ROD addresses contaminated soil onsite and contaminatedground water in the aquifer which provides drinking water to theCity of Liberty. The selected remedy specifies that infiltrationtrenches will be used to enhance the flushing of contaminantsfrom the soil. Ground water extraction will be used to draw theplume boundaries back toward the site and to remove contaminantsfrom the aquifer. The extracted ground water is discharged toTown Branch Creek.

None «of the comments received on the Proposed Plan requiremaking significant changes to the selected remedy. Comments werereceived regarding the potential ecological and health impactsfrom discharging extracted contaminated ground water to TownBranch Creek. Unless contaminant concentrations in the discharge.increase significantly, the^risk of adverse human health effectsor~envT?ontaenta^> harm arj

Attachment

WSTM:SPFD:REML:vh:GUNN February 27, 1991 3:RODTRME1 Jr*REML REML CNSL CNSL PBAF CIGL SPFD WwSTMGunn-^ing Richards Schiller Michaels Ritter Morby Wagoner

RECORD OF DECISION

DECLARATION

LEE CHEMICAL SITE

LIBERTY, MISSOURI

Prepared by:

Missouri Department of Natural Resources

Waste Management Program

Jefferson City, Missouri

And

U.S. Environmental Protection Agency

Region VII

Kansas City, Kansas

March 1991

DECLARATION FOR THE RECORD OF DECISION

SITE NAME AND LOCATION

Lee Chemical SiteLiberty, Missouri

STATEMENT OF PURPOSE AND BASIS

This decision document presents the selected remedial actionfor the Lee Chemical Site in Liberty, Missouri, chosen inaccordance with the Comprehensive Environmental Response,Compensation and Liability Act of 1980 (CERCLA) as amended by theSuperfund Amendments and Reauthorization Act of 1986 (SARA) and,to the extent practicable, the National Oil and HazardousSubstances Pollution Contingency Plan (NCP) ; 40 CFR Part 300(1990). The Regional Administrator has been delegated theauthority to approve this Record of Decision.

This decision is based upon the contents of the AdministrativeRecord for the Lee Chemical Site which was developed inaccordance with Section 113 (k) of CERCLA, 42 U.S.C. 9613 (k) . TheAdministrative Record is available for public review at the Mid-Continent Library, 1000 South Kent, Liberty, Missouri and at theEnvironmental Protection Agency (EPA) Regional Office, 726Minnesota Avenue, Kansas City, Kansas.

The State of Missouri has concurred with the selected remedyand determined that the selected remedy is consistent withMissouri laws and regulations.

ASSESSMENT OF THE SITE

Actual or threatened releases of hazardous substances fromthis Site, if not addressed by implementing the response actionselected in this Record of Decision (ROD) , may present animminent and substantial endangerment to public health, welfare,or the environment.

DESCRIPTION OF THE REMEDY

This final remedy addresses the principal threat at the Sitethrough the remediation of soil contamination and mobilecontaminants released into the groundwater thus reducing therisks posed by the Site.

The major components of the selected remedy include:

- Extraction of contaminated groundwater to removecontaminants from the aquifer of concern and to controlgroundwater movement away from the Site;

- Installation of an in-situ aqueous soil washing systemconsisting of infiltration trenches to enhance the flushingof contaminants from Site soils;

- Discharge of the extracted groundwater to Town Branch Creekunder the terms of an NPDES permit; and

- In the event that additional treatment of the dischargewater becomes necessary to meet health based risk levels,existing NPDES permit limits, or other applicable orrelevant and appropriate requirements; a contingency phaseproject consisting of air stripping or other treatmentmethods will be implemented to bring the discharge intocompliance.

These response actions would prevent future exposures tohazardous substances from this Site in the City of Liberty'sdrinking water supply by containing the contaminated groundwaterplume. These'actions will also remove the contaminants from thesoil and groundwater and restore the aquifer to acceptable levelsfor unrestricted use.

STATUTORY DETERMINATIONS

The selected remedy is protective of human health and theenvironment, complies with Federal and State requirements thatare legally applicable or relevant and appropriate to theremedial action, and is cost-effective. This remedy utilizespermanent solutions and alternative treatment technologies to themaximum extent practicable for this Site, and satisfies thestatutory preference for remedies that employ treatment thatreduces toxicity, mobility, or volume as a principal element.

Because this remedy will result in hazardous substancesremaining onsite above health-based levels, a review will beconducted within five years after commencement of remedial actionto ensure that the remedy continues to provide adequateprotection of human health and the environment.

Morris KayRegional AdministratorU.S. Environmental Protection AgencyRegion VII

Date

JOHNASHCROFT tHI^iijSr) Division of Energy\ n®K? **7<3ryy Division of Environmental Quality

Govtmor Mm&JMJ nwon of Geology' and Land Survey.„,. , . , . , Division of Management Services

G. TRACY MEHAN III Division of Parks, Recreation,Director STATE OF MISSOURI and Historic Preservation

DEPARTMENT OF NATURAL RESOURCESOFFICE OF THE DIRECTOR

P.O.Box 176Jefferson City, MO 65102

314-751-4422

February 21, 1991

Mr. Morris Kay 'Regional AdministratorU.S. Environmental ProtectionAgency, Region VII

726 Minnesota AvenueKansas City, KS 66101

Dear Mr. Kay:

The Missouri Department of Natural Resources has reviewed the Record ofDecision (ROD) for the Lee Chemical site in Liberty, Missouri. TheDepartment concurs with the selected remedy for the site detailed in theROD.

If you have any questions regarding this matter, please do not hesitateto contact me.

Very truly yours,

DEPARTMENT OF NATURAL RESOURCES

^ Director

GTM:jkh

c: Mr. Robert Morby, USEPA

RECORD OF DECISION

DECISION SUMMARY

LEE CHEMICAL SITE

LIBERTY, MISSOURI

Prepared by:




And


Region VII

Kansas City, Kansas

March 1991

TABLE OF CONTENTS

SECTION PAGE

1.0 SITE NAME, LOCATION, AND DESCRIPTION 1

2 . 0 SITE HISTORY AND ENFORCEMENT ACTIVITIES 1

3 . 0 HIGHLIGHTS OF COMMUNITY PARTICIPATION 6

4 . 0 SCOPE OF RESPONSE ACTION 7

5 . 0 SUMMARY OF SITE CHARACTERISTICS .7

6 . 0 SUMMARY OF SITE RISKS 11

7 . 0 DESCRIPTION OF ALTERNATIVES 22

8.0 SUMMARY.OF THE COMPARATIVE ANALYSIS OF ALTERNATIVES 26

9 . 0 THE SELECTED REMEDY 33

10.0 STATUTORY DETERMINATIONS 3.6

11.0 DOCUMENTATION OF SIGNIFICANT CHANGES 39

LIST OF FIGURES

PAGE

FIGURE 1. LOCATION OF THE LEE CHEMICAL SITE 2

FIGURE 2 . REGIONAL LOCATION OF LIBERTY, MISSOURI 3

FIGURE 3. LOCATION OF THE LEE CHEMICAL SITE INRELATION TO THE CITY OF LIBERTY'SWELL SUPPLY FIELD 4

11

LIST OF TABLES

TABLE 1. SUMMARY OF EXPOSURE PATHWAYS AND. EXPOSED POPULATIONS 14

TABLE 2. SUMMARY OF PARAMETER VALUES USEDTO ESTIMATE EXPOSURE 15

TABLE 3. SUMMARY OF EXPOSURE DOSES VIA GROUNDWATERINGESTION AND HEALTH RISK CALCULATIONS 17

TABLE 4. SUMMARY OF EXPOSURE DOSES VIA INHALATIONOF VOLATILIZED VOCs FROM GROUNDWATER ANDHEALTH RISK CALCULATIONS 18

TABLE 5. SLOPE FACTORS FOR CARCINOGENIC EFFECTSOF CHEMICAL CONTAMINANTS ATTHE LEE CHEMICAL SITE 19

TABLE 6. CHRONIC REFERENCE DOSES (RFDs) FORNONCARCINOGENIC EFFECTS OF CHEMICALCONTAMINANTS AT THE LEE CHEMICAL SITE 20

TABLE 7. NUMERICAL VALUES FOR CONTAMINANT-SPECIFICARARS FOR THE LEE CHEMICAL SUPERFUND SITE 21

TABLE 8a. SCREENING OF ALLUVIAL AQUIFER ALTERNATIVES(PAGE 1 OF 2) 28

TABLE 8b. SCREENING OF ALLUVIAL AQUIFER ALTERNATIVES(PAGE 2 OF 2) 29

111

SECTION 1.0 SITE NAME. LOCATION. AND DESCRIPTION

The Lee Chemical Site (Site) is located along Missouri Highway210, approximately 0.7 mile east of Missouri Highway 291 in theCity of Liberty, Clay County, Missouri, approximately 15 mileseast of Kansas City, Missouri as shown on Figure 1. Liberty'spopulation is approximately 17,000. The City is accessible byInterstate 35 and Missouri State Highway 291 as illustrated inFigure 2.

Currently, the Site is a lot of approximately 2.5 acres enclosedwithin a chain link fence. There are no permanent buildingscurrently located on the Site. An old water plant buildinglocated on the Site was demolished in 1983 and its foundation anda concrete tank that originally was used as storage while thewater treatment facility was in operation remain. Six abandonedmunicipal water supply wells known as Existing Wells 0 through 5(EW-0 through, EW-5) developed in the alluvial aquifer also remainonsite.

The surrounding land use is commercial/rural. A single.familydwelling exists to the northeast, cropland to the south, andcommercial properties to the north and west. The general slopeof the area is to the southwest toward Shoal Creek. The City ofLiberty obtains its drinking water from seven municipal wells,Water Supply Wells Number 1 through 7 (WSW1 through WSW7),drawing from the alluvial aquifer underlying the entire area.The municipal wells are located approximately 2,000 feet east-southeast of the site. Municipal Water Supply Well Number 2(WSW2) has been taken off the water supply system because of1,1,2-trichloroethene (TCE) contamination and is being dischargedto surface waters as part of an interim response actionimplemented by the City. The location of the Site in relation tothe municipal well supply field is shown on Figure 3.

SECTION 2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES

2.1 Site History

The Lee Chemical Site is located on property owned by the City ofLiberty that was utilized from about 1920 until 1962 as theCity's water treatment plant. In 1965, the City of Libertyleased the property to the Lee Chemical Company. The LeeChemical Company packaged and distributed commercial andindustrial cleaning solvents and other chemicals. In addition,Lee 'Chemical accepted for disposal chemicals from variouscommercial companies. Some of these chemicals were reprocessedonsite but many were stored onsite in 55 gallon drums. In 1975,the City of Liberty filed suit against the Lee Chemical Companyfor nonpayment of rent. Upon settlement of the suit, the City ofLiberty was able to retake possession of its property and gainaccess to the Site.

FIGURE 1

LEE CHEMICAL SITE

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LEE CHEMICAL S I T E

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2.2 Removal History

In 1976, the U.S. Environmental Protection Agency (EPA) notifiedthe City of Liberty that the chemicals stored on the property hadto be properly disposed of. Approximately three hundred 55gallon drums of wastes were removed from the abandoned site andproperly disposed of in July 1977. In 1979, low levels of TCEwere detected in the raw water from the City of Liberty's publicwater supply wells.

In the years following 1979, groundwater and soil samplescollected by the EPA and the Missouri Department of NaturalResources (MDNR) were found to be contaminated. MDNR inspectedthe Site in September 1982, and found deteriorated drums andchemical containers plus an empty 55-gallon drum labeled1,1,1-trichloroethane. Subsequently the City of Liberty and MDNRidentified the abandoned Site as a source of TCE contamination inthe City's water supply wells. In April 1983, the old waterplant building on the Site was demolished and only its foundationand adjacent concrete storage tank remain. Hazardous materialsfound in the structure were disposed of offsite. Clean soil wasused to restore the surface of the Site.

In May 1983, MDNR recommended that the City of Liberty implementspecific actions to reduce the TCE levels in the drinking watersupply. In January 1984, the City of Liberty began dischargingwater from a municipal water supply well, WSW2, to the MissouriRiver through an abandoned sewer line. In July 1984, the Citybegan discharging water from an onsite abandoned municipal supplywell, EW-3, and the water from WSW2 to Town Branch of Shoal Creekthrough a segment of abandoned water line. Both of these actionswere taken to contain the plume of groundwater contamination andreduce the levels of TCE in the water supply. This discharge wasauthorized by a -National Pollutant Discharge Elimination System(NPDES) permit issued by MDNR on August 3, 1984.

Monitoring of the TCE levels in the City of Liberty's watersupply *wells indicated that contamination was present in allwells as late as June 1986. Levels in WSW1, WSW4, WSW5, and WSW6were approximately 5 parts per billion (ppb) while levels in WSW2and WSW3 were as high as 330 ppb and 75 ppb, respectively.

Since March 1987, the concentration of TCE in the finished supplywater has been at or below the drinking water standard of 5 ppb.By June 1987, levels of TCE had decreased to below detectionlimits in WSW1, WSW4, WSW5, and WSW6; to 3 ppb in WSW3; and 97ppb in WSW2. Since 1987, only WSW2 and WSW3 have showndetectable levels of TCE. In early 1988, a new, uncontaminatedwell, WSW7, was placed in service to compensate for the loss ofWSW2 as a source of drinking water. Currently, no detectablelevels of TCE are found in wells connected to the City ofLiberty's water supply system.

From 1989 to 1990, the City of Liberty conducted Remedial Inves-tigation and Feasibility Study (RI/FS) activities to identify thetypes, quantities, and locations of contaminants. The RI identi-fied the following:

- TCE contamination is present in the soil at depths rangingfrom 1 to 20 feet below ground level, the highestconcentration was 11,000 micrograms per kilogram (ug/kg) ata depth of 20 feet, east of the old water plant buildingfoundation;

- A plume of TCE contamination suspended in and moving withgroundwater in the aquifer underlying the Site;

- TCE contamination in the now out-of-production WSW2 andabandoned onsite well EW-3; and

- No present contamination in WSW1, WSW3, WSW4, WSW5,WSW6, and WSW7.

Currently, the City of Liberty is continuing the implementationof the interim response action of discharging WSW2 and EW-3 toTown Branch Creek and the remaining municipal wells (WSW1, WSW3,WSW4, WSW5, WSW6, and WSW7) do not show detectable levels of TCE.However, should the interim response action cease, it isestimated that the plume of contamination in the alluvial aquiferwill reach the remaining municipal wells in a relatively shortperiod of time.

2.3 Enforcement History

The City of Liberty was initially notified by MDNR on August 26,1983 of its intent to propose the Lee Chemical Site for inclusionon the Registry of Confirmed Abandoned or Uncontrolled HazardousWaste Disposal Sites in Missouri. On January 1, 1984, theproperty was placed on the Registry pursuant to Section 260.440,RSMo. The EPA added this Site to the National Priorities List(NPL) on May 20, 1986. On August 5, 1988, the State of Missouriand the City of Liberty entered into an Agreement which providedfor the City to conduct an RI/FS. This agreement wassubsequently modified on October 20, 1989, and the City completedthe RI/FS in August 1990.

In May 1988, EPA and the City of Liberty entered into anadministrative consent order which required the City to continuethe interim response action described in the previous section.

i

SECTION 3.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION

The RI/FS and Proposed Plan for the Lee Chemical Site werereleased to the public on December 24, 1990. These two documentswere included in the administrative record file maintained at theMDNR, in Jefferson City, Missouri, the EPA Region VII DocketRoom, in Kansas City, Kansas, and the Mid-Continent Library in

the City of Liberty, Missouri. The notice of availability forthese two documents was published in the KANSAS CITY STAR onDecember 24 and 31, 1990 and the LIBERTY TRIBUNE on January 2 and9, 1991. A public comment period was held from December 24, 1990through January 23, 1991. In addition, a public hearing was heldon January 9, 1991. At this meeting, representatives from theMDNR and EPA answered questions about problems at the Site andthe remedial alternatives under consideration. A response to thecomments received during this period is included in theResponsiveness Summary, which is part of this Record of Decision.This decision document presents the selected remedial action forthe Lee Chemical Site, in Liberty, Missouri, chosen in accordancewith the Comprehensive Environmental Response, Compensation .andLiability Act of 1980 (CERCLA), as amended by the SuperfundAmendments and Reauthorization Act of 1986 (SARA) and, to theextent practicable, the National Oil and Hazardous SubstancesPollution Contingency Plan of 1990 (NCP). The decision for thisSite is based,on the Administrative Record.

SECTION 4.0 SCOPE OF RESPONSE ACTION

The selected remedial actions represent the final remedy for thesite. The principal threat at the site is the highly mobileVolatile Organic Compounds (VOC) contamination that moves fromthe source of contamination in the Site soils to the groundwaterand the mobile VOCs within the groundwater migrating toward theCity of Liberty's water supply. To address potential risks fromsuch exposure, the following remedial objectives were identified:

* Prevent potential exposure to contaminated groundwater;

* Protect uncontaminated groundwater for future use bypreventing further migration of the contaminated groundwaterplume;

* Restore the contaminated aquifer for future use as adrinking water source by reducing the contaminantconcentrations to regulated or health based levels (forexample 5 ppb or less for TCE); and

*• Remediate contaminated soils onsite such that no furthergroundwater contamination can occur.

SECTION 5.0 SUMMARY OF SITE CHARACTERISTICS

As a result of prior removal actions at the Site, all drums andcontainers have been removed and the buildings have beendemolished. Clean soil was used to restore the Site surface andthe Site is fenced.

A groundwater extraction system to confine the spread of theplume of contaminants and protect the remaining City supply wellshas been in operation since 1984. The extracted water iscurrently being discharged under an NPDES permit through an

abandoned water main to Town Branch of Shoal Creek. TCEconcentrations had been as high as 330 ppb and 851 ppb in WSW2and EW-3, respectively; and all of the rest of the City wellshave shown TCE concentrations, but at lower levels.

As a result of this interim response action, the levels of TCEhave dropped below detection limits in all of the City's supplywells and the concentrations of TCE in the extraction wells hasdropped to 45.30 ppb in WSW2 and 116.3 ppb in EW-3, in 1990.

The remedial investigation (RI) field work, conducted by the Cityof Liberty under MDNR oversight from early 1989 to mid 1990,included activities to define the bedrock surface, groundwaterflow regime, potential groundwater contaminant migrationpathways, and the extent of soil and groundwater contamination.

The discovery of containers, barrels, and visible contaminationin and around,the Lee Chemical Site was the initial indication ofpotential contamination. Further investigation in the immediatearea provided additional information to delineate the source ofcontamination. The predominant data that confirms that the LeeChemical Site and immediate surrounding area as the source ofcontamination is the analytical results from soil and soil gassamples collected around the Site. Groundwater samplingconducted at monitoring wells installed during the RI, at EW-3,and at Liberty supply wells also provides evidence that the LeeChemical Site area is the origination of contamination. Greaterdetail as to the extent of contamination in the soil andgroundwater is provided below.

Soil contamination was found at the highest levels immediatelyadjacent to the demolished water plant building foundation, withdecreasing levels away from the foundation. Soil contaminationextends from approximately 1 foot below ground level to the watertable (approximately 20 feet). The shallow depths ofcontamination detected indicates that surface disposal orspillage of contaminants occurred. TCE, the most commonconstituent, was reported at consistently greater values thanother volatile organic compounds (VOCs).

The highest subsurface soil TCE concentration, 11,000 microgramsper kilogram (ug/kg) was found 20 feet below ground level in thearea east of the demolished water plant building foundation.Soil gas data obtained during the RI generally corresponds to theareal extent of soil contamination detected which is summarizedas follows:

Soil contamination is present in samples collected in theimmediate area of the Lee Chemical Site at depths from1 to 20 feet.

Soil contamination at shallow depths (1 to 10 feet belowground level) is greatest surrounding the demolished buildingfoundation with levels decreasing away from the foundation.

- Soil contamination at depths up to 20 feet below ground levelare greatest around the demolished building foundation andjust east of that location with decreasing levels furthereast.

Groundwater samples and corresponding analytical data obtainedfrom monitoring wells, extraction well EW-3 located on the LeeChemical Site, and Liberty supply wells were evaluated todetermine the source and extent of contamination.

Groundwater contamination is currently restricted to the areaimmediately surrounding the Lee Chemical Site with a pathwayextending east to Liberty supply well WSW2. Sampling conductedat the monitoring wells located south of the adjacent Norfolk andWestern railroad showed no contamination above detection limitsfollowing the initiation of the interim response action.

When the analytical data were evaluated in conjunction with thehydrogeologic data, the following conclusions were drawn:

Pumping of EW-3 is controlling the migration of groundwatercontamination at the identified source.

- Pumping of WSW2 has effectively decreased the contaminationoriginally present in the other Liberty supply, wells.

5.1 Topography and Drainage

The City of Liberty's municipal well field is located in extremesouth central Clay County, Missouri. Physiographically, it liesin the flood plain of the Missouri River. The uplands, north ofthe area, consist of highly dissected glacial fill plains coveredby loess of varying thicknesses. The flood plain includesextensive coarse grained outwash materials. The general slope ofthe area is to the southwest toward Shoal Creek. There aremeander scars locally that include oxbow lakes or depressionsthat collect local runoff. Shoal Creek traverses the flood plainthrough an oxbow meander of the Missouri River, discharging intothe Missouri River approximately 1.5 miles south of the wellfield.

5.2 Geology

The geology consists of Pennsylvanian aged bedrock strataoverlain by unconformed Pleistocene and Recent unconsolidatedalluvial deposits. The topographic relief of the outcroppingbedrock upland area can be as high as 200 feet. The topographicrelief of the flood plain is approximately 30 feet. The Sitelies entirely on the Missouri River flood plain. Portions ofupland area are covered by various thicknesses of loess andglacial drift. Boulder zones have been encountered .at the baseof the valley fill that are believed to be glacially derived andmay be Pleistocene in age.

The bedrock formations that outcrop and subcrop in the vicinityof the Site are, in ascending order, the Pleasanton Group andKansas City Group. Except for possible minor local structuralfeatures, the formations dip gently to the west. The Kansas Cityand Pleasanton Groups are composed of interbedded layers oflimestone, sandstone and shale. The unconformed surface thatseparates the bedrock from the alluvium dips sharply to the eastfrom the Lee Chemical Site to the well field.

The Missouri River Valley is a partially filled trough incisedinto the bedrock formations. The grain size generally becomesfiner upward through the sequence. The thickness of the alluviumis controlled by irregularities in the bedrock surface. Regionalstudies indicate that the maximum thickness encountered east ofKansas City is 143 feet. The average thickness is approximately85 feet. The alluvium in the Site area .is composed of fine tocoarse sand, gravel, silt and clay. The distribution of thesesediment types generally conforms to a three-fold classificationsystem. The "boulder zone" is composed of coarse gravel androcks and lies at the base of the alluvium. The "bottom stratum"is composed of gravel and sand and lies at intermediate depths.The "top stratum" is composed of fine sand, silt and clay and isat shallow depths.

5.3 Soils and Surface Water Hydrology

Surface soil in the area consists primarily of the Haynie,Mondale, and Gillam silt loams. These soils are moderately welldrained, moderately permeable soils. They formed in calcareous,silty, or loamy alluvium. Slopes range from 0 to 2 percent.They have a Unified Soil Classification of CL-ML, CL, and a claycontent of 15 to 35 percent. Permeability ranges from 0.6 to 2.0inches per hour (4.23 X 10 to 1.41 X 10~3 centimeters persecond). The loess is thickest on the highly dissected hillsclose to the flood plain. It gradually thins to the northeast,where the ridge-tops are loess covered and glacial till is on theside slopes.

Surficial water within the Site area flows to the south andempties into Shoal Creek as evidenced by the local topography.The ground elevation at the Site area is approximately 730 feetabove sea level while the approximate elevation of Shoal Creek inthe vicinity of the Site is 720 feet. Town Branch empties intoShoal Creek on the western edge of the area.

5.4 Hydrogeoloqy

The principle aquifer in the area is the Missouri River alluvium.The regional flow of the aquifer within the Site area is to theeast. The groundwater flow in the Site area is heavilyinfluenced by the pumping of the City of Liberty's water supplywell field. The depth of groundwater in the Site area isapproximately twenty feet.

10

Hydraulic conductivity of the .aquifer material has been estimatedto range from 2,000 to 5,000 gallons per day per square foot.This is based on constant head permeameter tests from samples ofthe aquifer material. Estimates of the aquifer transmissivitybased on pumping test data range from 95,000 to 250,000 gallonsper day per foot. The values are typical for alluvial aquifers.The storage coefficient (specific yield) of the aquifer isestimated to range from 0.10 to 0.20 for the sedimentsencountered.

Yields from wells completed in the Missouri River Alluvium havebeen reported to be as high as 1,250 gallons per minute. Yieldsfrom the City of Liberty's wells range approximately 500 to 1,000gallons per minute when pumping at full capacity. Specificcapacity of these wells average approximately 110 gallons perminute per foot.

Recharge to the alluvial aquifer comes primarily frominfiltration of rainfall and, to a lesser extent, from thebedrock. Discharge from the aquifer can be attributed to seepageinto the Missouri River, pumping wells, and evaportranspiration.Pumping wells may cause infiltration of water from the river tothe aquifer by reversing the hydraulic gradient.

SECTION 6.0 SUMMARY OF SITE RISKS

As part of the RI/FS process, a risk evaluation was conducted toestimate the human health and environmental risks associated withpossible exposures to contaminants detected at the Lee ChemicalSite. Both carcinogenic and noncarcinogenic adverse healtheffects were analyzed using a reasonable maximum exposureestimate. This risk analysis shows that an unacceptable excesscancer risk for a reasonably maximum exposed (RME) individualwould result if the City of Liberty discontinued the currentinterim response action to control the plume of contaminationcoming from the Site and returned the wells currently pumping aspart of this action to use as supply wells for the community.The noncarcinogenic risks analyzed were below levels of concern.

The risk evaluation also analyzed the potential short-termadverse health effects associated with air emissions from thedischarge of contaminated groundwater. This discharge is part ofan interim response action which began in 1984 to removecontaminated groundwater from the aquifer and to capture theplume of groundwater contamination thus protecting the City ofLiberty's remaining water supply wells. The interim action,described as Alternative II, utilizes WSW2 and EW-3 as extractionwells and discharges the extracted water through an old watermain to Town Branch Creek. As a result of this action,contaminants are no longer detected in the remaining City supply•wells. This part of the risk analysis, assumed a worst caseexposure and found that the risks from the air emissions at theoutfall were insignificant.

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The excess lifetime carcinogenic risk level is expressed inscientific notation, e.g., 1 X 10~. An excess lifetime cancerrisk of 1 X 10~6 indicates that as a plausible upper bound therisk of developing cancer as a result of site related exposure toa carcinogen over a 70-year lifetime under specific exposureconditions at a site is approximately one in one million.Cumulative risk levels of 1 X 10~6 to 1 X 10~4 can be used todetermine the environmental significance of the risk incurred andis a target range for remedial actions. A cumulative riskgreater than 1 X 10 is considered to be unacceptable. Risksbetween 1 X 10 and 1 X 10~4 are considered to be potentiallyunacceptable, and risks less than 1 X 10~6 are considered to beinsignificant.

Noncarcinogenic effects were analyzed using hazard indices andhazard quotients. The hazard index is the comparison ofestimated exposure (chronic dose) with reference doses (i.e.acceptable daily intake). The hazard quotient is the sum of thehazard indexes for a specific pathway. If the hazard index isless than one for an exposure pathway, no adverse health effectswould be expected.

The contaminated media considered in the risk evaluation weresoil and groundwater onsite and groundwater offsite. Soilsampling data in the RI indicates that no quantifiableconcentrations of hazardous substances exist in the near surface(0 to 1 foot) Site soils. However, deeper (5 to 20 feet) soilsamples did contain concentrations of contaminants which couldlead to potential exposures during construction activities atthose depths. Both the depth to significant levels of soilcontamination and the Site fencing limit public access tocontaminated soil. As a result, this pathway of exposure was notincluded in the calculation of the overall site risks. However,the migration of contaminants from the deeper soils to thegroundwater is expected to be a continuing source of groundwatercontamination.

The principal threat at the Site is the highly mobile VOCcontamination that moves from the source of contamination in theSite soils to the groundwater and the mobile VOCs within thegroundwater migrating toward the City of Liberty's water supply.Before the interim response action was taken, samples from all ofthe existing Water Supply Wells (WSW numbers 1 through 6) showed1,1,2-trichloroethene (TCE) contamination. Samples from WSW2contained concentrations as high as 330 parts per billion (ppb),and sampling of an abandoned City supply well (EW-3) on the LeeChemical Site showed concentrations of TCE as high as 851 ppb.

A review of the data in the RI lead to the identification of fiveindicator chemicals to be considered in the risk evaluation.

12

The five contaminants of concern are as follows:

a) 1,1,2-trichloroethene (TCE),b) 1,l-dichloroethane,c) 1,1-dichloroethene,d) trans-l,2-dichloroethene, ande) 1,1,1-trichloroethane (TCA).

TCE was the indicator chemical detected most frequently and inthe highest concentrations. TCE is a probable human carcinogen,and two other indicator chemicals (1,l-dichloroethane and1,1-dichloroethene) are potential human carcinogens. All of theindicator chemicals are capable of causing acute and chronicnoncarcinogenic health effects in humans. Vinyl chloride has notbeen detected in any of the samples taken at the Site.

Concern over the potential impacts of hazardous substancesreleased from,the Lee Chemical Site focuses on the residentialpopulations served by the City of Liberty's water system. TheCity of Liberty's water system serves 6,280 households or placesof business, which is approximately 20,000 people. The exposurepathways considered in the risk evaluation were ingestion andinhalation of VOCs from contaminated groundwater. Table 1summarizes the exposure pathways and exposed populations used inthe risk calculations, and Table 2 summarizes the exposureparameter values.

Another exposure scenario considered in the risk evaluation isrelated to VOC emissions from the interim pump and dischargeaction which is ongoing at the Site. The selected alternativeuses this same discharge method. Potential risk to industrialworkers and residential populations near the discharge point onTown Branch were evaluated. Risks, based on air modeling,associated with the extraction well discharge point on TownBranch were found to be insignificant.

Exposure due to direct contact with or ingestion of contaminantsfrom Site soils were not considered in the risk evaluation,because the lack of contaminants in shallow Site soils and theSite fencing combined to make the likelihood of these routes ofexposure remote. Exposures from the ingestion of surface waterfrom Town Branch or Shoal Creek were also very unlikely and notincluded in the computation of site risks due to the limitedaccess the public has to these creeks, their low flow rates, andthe low concentrations of contaminants that enter these streams.

The carcinogenic risk based on a reasonable maximum exposure(RME) associated with the use of contaminated groundwater fromthe Lee Chemical Site as a source of drinking water for the Cityof Liberty is 2 X 10" . This estimate combines the exposuresfrom ingestion and inhalation of Site contaminants and indicatesthat as a probable upper bound there would be two additionalcancers in a population of 10,000. Therefore, the carcinogenicrisk from this exposure scenario is unacceptable pursuant to therisk levels identified in the NCP. The carcinogenic risk

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TABLE 1

SUMMARY OP EXPOSURE PATHWAYS AND EXPOSED POPULATIONS

EVALUATED IN THE RISK EVALUATION OF THE LEE CHEMICAL SITE

EXPOSURE MEDIUM EXPOSURE rotm- EXPOSURE ROUTO POTHNTIAI1.Y EXPOSED OOMMBNIS

Groundwaler Lea Chemical SiteWcH AIM

Ingest ion

Qroundwater SICWell Area

Inhalation

Oroundwater

Gfoundwater

Suffice WaterContaminated byGroundwaler Discharge

Surface WaterContaminated byGroundwaler Discharge

Liberty Wen *2

Liberty Well #2

Town BranchDischarge Point

Town BranchDischarge Point

Ingest Ion

Inhalation

Inhalation

Inhalation

Residential: Children andadults using potable watersupplied from well OW-3.

Residential Children andadults being exposed tovolatile! while showeringwith water from well EW-3.

Residential: Children andadults using water suppliedfrom Well 02.

Residential; Children andadults being exposed tovolatile* while showeringwith water from Well f 2.

Residency. Children and adult*residing at the mini • warehouse,facility downwind of the extractionwells discharge point.

Indmlrlal/Commefrial:Workers at business downwindof the extraction welldischarge point.

Attaining that the City of Liberty wOlInstall • supply well it the site*, In th« are*

.of concern, or will resume vse of wetlEW-J n • supply well, for purposes ofthe risk assessment this area includes wellsBW.J, 1-83. 2-83, 3-83, 443, MW-2-86,MW-3-86. Evaluated risks to adults only.

Assuming that the dry of Liberty wfflInstall • supply wen at the site, In the areaof concern, or will resume use of wellEW-3 as a supply well. For purpose* ofthe risk assessment this area Includes well*EW-3,1-83. 2-83, 3-83, 4-83, MW-2-86,MW-3-86. Evaluated risk* to adult* only.

Assuming that the Oty of Liberty wfflInstall a tupply wefl at the *He In the areaof concern or will resume •*• of Wefl fta* a (apply well evaluated risk* lo adult*only.

Assuming that the Chy of Uberly wWInstall a supply wefl at the aha In the areaof concern or win resume aM of Wed 91a* a supply wen. Evaluated risk* to adult*only.

A**vmlng thai the Inouov air concentrationto the same a* the outdoor levelEvaluated risks to adill* only.

Assuming that the Indoor air concentrationb the urtie a* the outdoor level.

TA1HJB 2

SUMMARY OP PARAMOUR VALUES USED TO BS1TMATB EXTOSURD

VARIAITUJ VALUE USI5D IIRIEn RATIONAIJB

Chemical Concentration

Exposure Frequency (dayi/yw)ResidentialIndustrial/Commercial

• Exposure Duration (year)Residential (Average Exposure)Residential (RME) (a)Industrial/Commercial

Contact RateOroundwater Ingeslton JL/day)Air Inhalation Rate (mj/day)

ResidentialIndustrial/Commercial

Body Welfht (k|)

Avenging Time (year)For Carcinocenle EfTectt

Resldential/lndustrial/CommerclalPor Non<arrino(en<c Effeeis

Resldeniial (Average Biposure)Residential (RME)Industrial/Commercial

*

Time Convection Factor for Averaging Time(day/year)

Please rtfer to Tables 7-t to 2-2

365260

93040

208.8

70

70

93040

365

Daily (by convention)Assuming 5 work days/week for 52 weeks/year

National median lime (50th percenllle) at one residence (b)National upper-bound, time (90th percentlle)Upper-bound workers eiposure duration used by ACOIH/OSHA

Adult, 90th percentile (b) ,

Adult, average (b)Assuming I.I nr/hour for 8 hours/day

Adult, avenge (b) PRC did not evaluate risk* to dilMmk

Lifetime (by convention)

National median time (50)h percentlle) at one residence (b)National upper-bound time (90th percentlle)Upper-bound workers' exposure duration used by'ACOIH/OSHA

Daily

(0UJ. ETA (IWta), Ptaon Hadboak, EPA *90/M»/M1.19*

calculations for the ingestion and inhalation of VOCs fromcontaminated groundwater are summarized in Tables 3 and 4. Thebasic toxicity information used in these calculations is listedin Table 5. This risk level represents the baseline risk whichwould remain if no action was taken at the Site. The value of2 X 10~4 is based on the data in the RI which was collected afterthe interim action was taken at the Site. The risk level wouldbe approximately an order of magnitude higher if data from beforethe interim action was used in the risk calculations.

Groundwater from the Lee Chemical Site is not currently used tosupply drinking water to the City. Under current Siteconditions, with the interim response action operating, nodetectable levels of contaminants were found in samples takenfrom the Liberty supply wells, and risks associated with theextraction well discharge point on Town Branch are insignificant.

The noncarcinpgenic risks associated with all of the indicatorchemicals in all the exposure scenarios considered do notrepresent any significant concern for adverse health effects.The noncarcinogenic risk calculations are also summarized inTables 3 and 4 and the basic toxicity information used in thecalculations is listed in Table 6.

Cleanup goals for the groundwater will be based on Applicable orRelevant and Appropriate Requirements (ARARs), in particular,state and federal drinking water standards and state waterquality standards for groundwater (Table 7).

No rare, threatened, or endangered wildlife species wereidentified in the vicinity of the Site during the RI. There havebeen no samples taken of sediments or organisms from Town Branchor Shoal Creek to assess the environmental impact of thedischarge. There have been in-stream water quality samplescollected at the confluence of Town Branch and Shoal Creek, butnone of these samples has shown significant concentrations ofVOCs. The concentration of TCE entering Town Branch at theoutfall has consistently been below 90 ppb since the beginning ofthe RI. Based on that data, it would appear that almost completevolatilization of the TCE occurs between the point of dischargeand the confluence. However, further investigation of the needto sample the creek sediments and organisms will be considered aspart of the design of the remedial action.

Actual or threatened releases of hazardous substances from theSite, if not addressed by the preferred alternative or one of theother alternatives besides Alternative I (the no-actionalternative), may present an imminent and substantialendangerment to public health, welfare, or the environment.

16

TASLI 3

SUMMIT Of EXPOSURE DOSES VIA CROUND WATER INCESTION AND MAITN RISK CALCULATIONS

imam PARAMETERS!

Average Iipoaur*Reasonable KM. Cupoiur*

EXPRESSION FOt IM1AKE DOSCl

Cround tartar InfMtton (average)Cround Mttr Invention (RNt)

exposure) Exposure Contact Wt. Conv.Duration Freq. Rata Factor.

(yr) (day/yr) (I/day) (og/ug)9 345 2 0.00130 363 0.001

(Carcinogenic) (Non-careInogenlc)

J.7I-OA1.2E-03

2.9E-OS2.9E-05

Adult Avt. Tlt» TlM Cow.Weight Cancer Factor

(kg) Cyr) (day/yr)70 70 363

• 70 70 345tup. Duration • tup. Frequency • Contact Rate • Unit Convaralon factor

• . »---•-."«•««•••••«•«-••-•-«•»«»•»»•••••••»..•»»....i.... .............

•ody Weight • Averaging T!M • tla* Conversion factor

| CNCNICAIS Of CONCERN| * (IT LOCATION • PtESCNf/niTUM)|IU>AC N*M CAS NO.1ILK CHEMICAL sue urns (runmc)jdlchlorMthtn* (1.1-) 75-35-3jdlchlorMthtna <l,1-) H-35-4jdlchlorottlMna Ct-1.l-) S40-5?-0|trlckloro«thana C1.1.1-) 71-55-*Itrlchlorcwthcna 77-01-4(lOtAL CANCER tISK/NAIARD INDEK1ILIKRTT EXTRACTION WELL n (FUTURE)jdlchtorootliana (1,1-) 75-33-3jdlchlorovthona (1.1-) 75-33-4jdlchlorovthina (1-1.2-) 540-59*0jtrlchlero«thana (1.1. M 71-53-4(trlchlorocthcna 79-01-*(TOTAL CANCER RISK/HAZARD INDEX1ILISERTT FIELD sumr UELLS (PRESENT)jdlchlorovtliant (1,1-) H-35-3IdlcMorovtMna (1,1-) 73-33-4jdlchlorotthtna (t>1,2>) 5*0-59-0jtrlchloretthana (1,1,1-) 71-55-4jtrlchlorootlwna 79-01-*(TOTAL CANCER RISK/NAIARO INDEX1

CONCENTRATIONS 1Avaraa* RME(OB/L) (ooA)

1.4E«00 1.4E*004.3E«00 S.SE«002.0E*00 2.3E*003.9E*01 1.5E«023.3£»01 1.3E*02

'

i.BE«00 2.0E«001.4E«00 1.66*007.5E«00 i.K«001.7C«00 t.6E«00*.9E«01 7.6E«01

.5E«00 1.31*00

.5E«00 1.4E«00

.8E«00 2.1E«00

.5E«00 1.5E«00

.4E«M 1.8E«00

TOXICHT VALUES FOR ORAL ROUTEVt. of SF (a) RfD (b)Evldcnc* 1/(a9/k|-d) (a«/kg-d)

C 9.1E-02 1.0E-01C 4.0E-01 9.0E-03

2.0E-029.0E-02

•2 1.1E-02 '

•2 9.1E-02 1.0E-01C 4.0E-01 9.0E-03

2.0E-029.0E-02

•2 1.1E-02

•2 9.11-02 1.0E-01C 6.0E-01 9.0E-03

2.0E-029.0E-02

•2 1.1E-02

-

CAOUND IMIER INCESTION (AVCRACt)Cancor Doit Cancor N/C Doaa Raiard(•oAfd) Risk (««/kf-d) Quotient

5.9E-04 5. 36-07 4.4E-03 4.4E-041.4C-05 9.5E-04 1.2E-04 1.4C-027.3E-04 3.7E-05 2.9E-031.4E-04 1.1E-03 1.31-021.9E-04 2.1E-04 1.5E-03

1.2E-03 2.9E-02

4.4E-04 4.0C-07 3.1E-03 S.lt-043.1E-04 3.1E-OA 4.0E-03 4.4E-032.8E-05 2.1E-04 1.1E-02*.2E-04 4.9E-03 3.4E-042.5E-04 2.8E-04 2.0E-03

«.5E-0* l.tt-02

.31-0* S.OE-07 4.3E-03 4.SE-04

.5E-04 3.3E-06 4.3E-03 4.8E-03

.4E-04 3.1E-03 2.4C-03

.5E-04 4.3E-03 4.6C-04

.9E-04 4.5E-08 4.4E-033.9E-06 I.2E-03

CROUND WATER IMCSTION (RNK) |Canear DOM Cancer N/C DOM Naiard .(a«/kf-d) Rlak (aaTkf d) Quotient

2.01-03 1.K-0* 4.6E-03 4.M-044.7E-05 4.0E-05 1 .61-04 1.7E-022.BC-03 A.6C-03 3.3E-031.8E-03 4.11-03 4.4E-021.6C-03 1.71-03 3.6E-03

S.9E-03 t.TE-02

2.41-03 2.2C-0* 3.7E-03 S.71-042.0E-OS 1.2E-05 4.4C-03 3.1E-031.1E-04 2.3C-04 1. 31-022.2C-03 3.1E-05 3.7E-049.5E-04 1.0E-03 2.2C-03

2.4E-05 1.9E-02

1.8E-03 1.71-0* 4.31-03 4.31-042.0E-03 1.21-03 4.41-03 3.1E-032.4C-03 *.OE-03 3.0E-031.K-03 4.3E-03 4.8E-042.2E-03 2.41-07 3.1C-OS

1. 41-03 9.0E-OS

1 , .,.,- -

FOOTNOTEI(a) Stopa FactorN/C Non-carclnooonlc

(b) Chronic Reference Dote

00

TABLE A.

SUMNART OP EXPOSURE DOSES VIA INHALATION Of VOLATILIZED VOCe FROM GROUND IMTER AND HEALTH RISK CALCULATION (•)

»AMMETEHSl

Averote Iipoour*Heatonoblo NM.

tXTtESSION F« INTAKE OOStt

lirpotur* EupMuro Contact Ul. Conv.Duration Froq. Rate Factor

(yr) fday/yr) '(I/day) (a«/ug)f 365 2 0.00130 365 2 0.001

(Carcinogenic) (Han-carcinogenic)

Adult Avt. Tlaw KM Com.Weight Cancer Factor

(kg) (yr) (day/yr)70 70 365 .70 70 365

ERP. Duration • E*p. Fro(-ueney • Contact Rate • Unit Coiwertlon Factor• ..».>.......«......•....'.•».«.•.....................................

Body Weight • Averaging Tla* • Tlrai Conversion FactorCroud *eter Inhalation (average)Crowd Mttr Inhalation (RNC)

CNENICALS OP CONCERNfIT LOCATION • MESENT/FUTURI)

IUTAC NOT CAS HO.• 1

ILEE CHEMICAL SITE VEILS (FUTURE)jdlchloroethane (1.1*) 75-35*3(dlchloroothene (1.1*) 75*35-4jdlchloroathene (t-1.2-) 5(0-59-0trlchloroethane. (1.1.1*) 71-55-4trlchloroetheno 79-01-4TOTAL CANCER RISK/HAZARD INDEX

LIIEITV EXTRACTION HELL 12 (FUTURE)dlchloroethane (1.1-) 75-35-Sdlchloroethene (1.1*) 75-35-4jdlchloroethena (t-1.2-) 540-59-0jtrlcMoroothano (1,1,1-) 71-55-6jtrlchloroetheno 79-01-4(TOTAL CANCER RISK/HAZARD INDEX1(LIBERTY FIELD SUPPLY tens (PRESENT)jdlchloroethano (1,1-) 75-35-3jdlchloroothono (I.1-) 75-35-4jdlchloroothtno (t-1,l-) 540-59*0jtrlchloroethane (1.1.1*) 71-55-6(trlctitoroethene 79-01-6(TOTAL CANCER RISK/HAZARD INDEX1 . .

j.Ti-061.2E-OS

CONCENTRATIONSAverage RNC |(ug/L) (ug/L) |

1.4f»00 1.4E»004.3E«00 S.5E«002.0E«00 2.3E*003.9t»01 1.5E«025.3E»01 t.3E«02

•

1.K«00 1.0E*001.4E«00 1.4€»007.5E«00 t.BE»001.7E«00 1.BE«006.9E«01 7.8E«01

.51*00 1.5E»00,5E»00 1.4E«00.8E«00 2.1E»00.5E«00 1.5E»00,4E»00 1.6E«00

2.9E-052.9E-05

TOXICITT VALUES • INHALATIONWt. of SP (•) NfD (b>Evidence 1/(«o/kfd) (•o/kf-d)

1.0E-01C 1.2E»00

3.0E-01•2 1.7E-02

1.0E-01C 1.2E«00

3.0E-01•2 1.7E-02

1.01*01 .C 1.2E»00

s.oe-oi•2 1.7C-02

1

•

GROUND WATER INNAIATIM (AVERAGE)Cancer Dot* Canctr N/C Poto Nstard(•0/kf-d) Rltk (Mo/kf-d) Ouotlwit

S.9E-06 4.6E-05 4.6E-041.4E-05 1.9E-05 1.2E-047.3E-04 5.7E-D51.4E-04 1.U-OJ S.K-031.9E-04 S.3E-06 1.5E-OS

2.2E-05 4.2E-OJ

6.6E-06 S.1E-OS 9.11*045.1E-06 A.2E-06 4.0E-052.BE-05 2.1E-046.2E-06 4.9E-05 1.61-042.5E-04 4.3E-06 2.0E-OI

1.0E-05 6.8E-04

.51*06 4.3E-05 4.3B-04

.5E-06 6.6E-06 4.3E-05

.6E-06 9. IE-OS

.5E-06 4.3E-05 1.41*04

.9E-06 1.0E-07 4.6E-056.71-04 9.71-04

GROUND IMTER INHALATION (RNE)Cancer Dot* Cancer N/C Ooao NoiartJ(••/krd) Rlek (•t/ki-d) Quotient

t.OC-09 .61-09 4.6E-046.7E-09 •.11*09 .AE-042.81-09 .6E-051.8E-01 .1E-OS 1.4E-021.6E-03 t.TE-05 .6E-03

1.1E-04 1.4E-02*

2.4C-09 5.71-05 9.7E-042.0E-05 2.41*09 4.6E-091.1E-04 2.SE-042.2E-05 5.1E-05 1.71-049.5E-04 1.6E-05 2.2E-03

4.0E-09 7.4E-04

1.81-05 .3E-05 4.SC-04l.OE-05 2.41-09 .6E-052.6E-05 .OE-051.BE-09 .3E-05 1.41-042.2E-05 S.n-07 .1E-05

2.4E-09 9.71-04

FOOTNOTEt(a) Intake doeM via Irtialatlon of votatlted VOCi ffron ground uater ore aiauacd to bo equivalent to I now 11 en doeee of 2- lltert/day(b) Slope Factor (c). Chronic Reference Dote N/C Non-careInooenlc

*% tAIlt 5

StOW MCtMS fOR CARCINOGENIC EffECTS Of CHEMICAL CONTAMINANTS AT THE IEE CHEMICAL tITI

. CHEMICAL.

•

^ •1,1-Dlchtoroethana

1,1-Olchloroathana

t-1,2-DlcMoroethana

1,1,1-Trlchloraathana

H*VO

i r i en i aroatnena

•

fOOTNOTES

CAS NO.

75-34-4

75-33-4

540-39-0

71-55-4

_

SLOPE FACTOR(SF) (a)1/(a«/kg-d)

9.11-02(Oral) •

4.0E-01(Oral)1.2EMM

(Inhalation)

••

1 4V.A9•iC'Uc

(Oral)1.7E-02

(Inhalation)

,

WEIGHT -Of-EVIDENCE

CLASSIFICATION (

1e 1

e

e

0

.

« '

H

TTPE Of CANCER Sf IAS IS/Sf SOURCE (C)

b)

.HenanglosarcoM (Oavage/

JHEAST1

Adrenal tumor* (Oral gavaga/(IRIS

Kidney adenocerclnoM (Inhalation/(IRIS

, iF' "

IRIS'

liver • |urai gavaga/j NEAST

lung (Inhalation/JHEAST

.

COMMENTS

-

Not located In lilt ar NEAST

No quantitative attlaataof oral ar Inhalation Sfappaarad In IRIS ar NEAST

•-

;

(10 IRIS «ab tho flrtt aourca consultad for If value*. If no Sf Mat available In IRIS, NEAST wit consulted.Only tho wat currant Sf value* era used,

(b) The EM classification •yateai for welght-of-ovldeneo la at follow*!A • NuMn carcinogenSI • Probable huwn'carcinogen) Halted huam data12 • Probable huasn carcinogen; tuffIclent evidence In anlMla and Inadequate or no evidence In huaentC • •oaelble huasn carcinogen ^ ^ •0 • Not clattlfablo at-Jo huean corclnotfenlclty

. E • Evidence of nonearclnogenklty for'huaont(C) IRIS* Integrated Rlak Information Syatea (EPA, 1990a)|

«A$T« Health Effect* Atteswwnt Sumary Tablet, fourth Quarter 1989 (EPA,1990b).

TABLE -6 •

CHRONIC MFERENCt DMCI (RfDs) rM NONCARCINOGENIC EFFECTS OF CHEMICAL CONTAMINANTS AT TMt LEI CHEMICAL tITf

COMPOUND

•1.1-DlcMoroethant

"1,1-Olchloroetheno

..•

1.2-t-OfcMoroothtnt

1.1.1-lrlchloroetham

too

""

Trlchloroethene

FOOTNOTES

CAS NO. (a)

75-34*4•

73-33-4

• 340-39-0

71-55-e

79-01-0

'

CHRONIC RfO (b)(mg/kg-day)

1E-01(Oral)1E-01

(Inhalation)

9E-OS(Oral)

»-02(Oral)

9C-02.(Oral)

(Inhalation)'

.

• •

CONFIDENCE CRITICALLEVEL EFFECT

.» (None

(Kidney damage

1Medium (Hepatic lesions

ILOM (Increased serum alkaline

(phospato

1Medium (No adverse affects; flight

(growth retardation

(Nepototoxlcltr

'•« • ..

.

I t

RfD BASIS/ UNCERWINTr ANDRfO SOURCE MODIFYING FACTORS

.Iritaletlon/HEAST «)|UF- 1000 for N.A.8 (•)

.Iriialatlon/HEAST (UF- 1000 for N.A.I

Uater/IRIS (d) |UF- 1000 for N.A.lINF- 1

Uater/IRIS |UF- 1000 for M.IINF- 11

Inhatatlon/IRIS (UF- 1000 for N.A.IINF- 1

Inhalatlon/HEAST (UF- 1000 for R.A.I

••'

'

COHNENTS

-«

..

••.

••

••

••

No RfD Mas located for ICEIn IRIS or HEAST

*

(a) Chewlcat Abstract Service nuater • • unique Identification nunber for a che»leal co*pwid.(b) Only the aaat current RfO values appearing In IRIS or HEAST were selected for thla table.(c) NEAST* Health Effects Aaeessamtt Sumary Table* First/Second Quarters 1990 (EPA. 199%).(d) IRIS* Integrated Risk Information Syatcai (EPA, 1990a).(e) Uncertainty adjustment used to represent ceofclned N.A.S. and I extrapolations.

Uncertainty adjustments! H» Variation In human sensitivity;A« Animal to huaan titrapolatlon;S« Extrapolation from tubchronlc to chronic No Observable Adverse Effect Level (NOAEl).•i* Extrapolation from louett Observable Adverse Effect level (LOAEL) to NOAEL.

Modifying factors are applied to reflect profesdonal Judgement regarding additional uncertainties In the Studyand the entire database.

TABLE 7

NUMERICAL VALUES FOR CONTAMINANT-SPECIFIC ARARSFOR THE LEE CHEMICAL SITE

CONTAMINANT

1,1-Dichloroethane

1,1-Dichloroethene

t-1,2-Dichloroethene

1,1,1-Trichloroethane(TCA)

1,1,2-Trichloroethene(TCE)

SAFE DRINKING WATER ACT

MCL MCLGug/1 ug/1

7 7

100 100

200 200

EPA 304(a) WATER QUALITY CRITERIA

CONTAMINANT

1,1-Dichloroethane

1,1-Dichloroethene

t-1,2-Dichloroethene

1,1,1-Trichloroethane(TCA)

1,1,2-Trichloroethene(TCE)

FreshwaterCriterion

Concentrations

Acuteug/1

Chronicug/1

10~6 Risk forCarcinogens fromConsumption of:

Water & OrganismsOrganisms Onlyug/1 ug/1

0.057

3094

2.7

3.2

173077

80.7

21

SECTION 7.0 DESCRIPTION OF ALTERNATIVES

Alternative I:

Alternative I is a no action alternative, required by the NationalContingency Plan (NCP) and SARA. It is the baseline againstwhich the effectiveness of other alternatives are judged. Underthis alternative, monitoring, control, or remediation ofcontamination will not take place. Site perimeter fencing isrequired and is already in place. Groundwater contamination willspread throughout the area making new water wells at a distantlocation a requirement for the City of Liberty's water supply.Currently uncontaminated supply wells will, in time, becomecontaminated at levels above Maximum Contaminant Levels (MCLs).

Alternative II;

The remediation that has been taking place at the Lee ChemicalSite and the 'Liberty well field is pumping EW-3 and WSW2 to TownBranch Creek. Under this alternative, the site perimeter needsto be fenced and it is already in place. The City of Libertywill need to restrict any new well construction in closeproximity to the Lee Chemical Site. If this alternative ischosen, groundwater monitoring will be required. Air and surfacewater monitoring at the Town Branch outfall is also a requirementto meet the ARARs.

Groundwater quality data from the RI showed that between 1982 and1989, TCE concentration generally decreased at WSW2 from 330 ppbto approximately 65 ppb with a temporary low of 20 ppb. EW-3also showed a declining trend of TCE between 1984 and 1989. TheTCE concentration in 1984 was over 851 ppb and reduced to81.6 ppb in 1989.

The level of groundwater contamination suggests that both ofthese wells will continue to produce groundwater.above the MCLfor TCE and other constituents for an extended period of time.Although the decline of contamination is fairly slow, thecontaminant plume within the aquifer is contained withinapproximate limits described in Section 1. All other supplywells in the Liberty well field are producing groundwater belowMCL levels. This alternative is estimated to require 25 yearsfor site restoration at a present worth cost of $814,000.

Alternative III;

Alternative III follows all basic requirements of Alternative II.In this alternative, well EW-3 will be replaced by a highcapacity well, a more efficient well penetrating the fullsaturated thickness of the aquifer and located near the center ofthe contamination source. By constructing an extraction well toMissouri public water supply standards, the following goals willbe achieved:

22

a) Radius of influence within the Lee Chemical Site will befurther increased so that the entire contaminant plume can becaptured and limited to the site boundaries.

b) Water withdrawal from all depth levels will enhance cleanup of the aquifer.

c) Groundwater produced by Liberty well No. 2 will decreasebelow MCL levels and all other wells in the Liberty well fieldwill remain free of contamination.

Liberty well No. 2 will be pumped continuously until the MCLconcentration of 5 ppb of TCE and 200 ppb of TCA is reached atthis location.

In this alternative, the transport of contaminants through soilwill be inducted by local precipitation. Although thecontaminant plume will be contained within the radius ofinfluence of this high capacity well, an extended period of timewill be required to meet groundwater health based standardswithin the aquifer at the Lee Chemical Site.

Groundwater monitoring will be required for monitoring wells ator in the vicinity of the Lee Chemical Site. More stringentmonitoring programs for air and water samples will be required atTown Branch outfall locations. This alternative is estimated torequire 25 years for site restoration at a present worth cost of$767,000.

Alternative IV;

Alternative IV is the addition of a soil flushing system toAlternative II. All monitoring requirements explained inAlternatives II and III will be applicable to this alternative.Fencing the perimeter of the site is a requirement and is alreadyfulfilled.

The soil flushing system will cover an area of approximately 800feet in length (east to west) and 200 feet in width (north tosouth). Two foot wide trenches dug to a depth of approximately 3feet below ground level will be constructed at approximately 10foot centers throughout the area described above. At the bottomof the trenches, flexible perforated tubing will be emplaced andthe excavation will be backfilled with permeable material. Thesystem will be connected to a clean water supply from the Libertywell field.

The RI identified the vadose zone, the soils above the watertable, within the Lee Chemical Site area as the principal sourceof contamination. This alternative will enhance the flushing ofcontaminants through the vadose zone, thereby reducing the levelof contamination at the source. Contamination flushed from thevadose zone and escaping the influence of EW-3 will travel toLiberty well No. 2.

23

A relatively extended period of time will be required to bringgroundwater within the Lee Chemical Site within acceptablelevels.

Withdrawal from Liberty well No. 2 will continue to contain thecontaminated groundwater plume offsite. This alternative isestimated to require 15 years for site restoration at a presentworth cost of $860,000.

Alternative V;

This alternative is a combination of gravity induced soilflushing and Alternative III. The alternative will follow allmonitoring requirements and restrictions as explained inAlternative IV. Due to the elimination of limiting conditionsstated in Alternative IV, the cleanup of the Lee Chemical Sitecontamination will be expedited. The extraction well constructedto Missouri public water supply standards will be strategicallylocated at the center of the zone of contamination so the radiusof influence of the well will extend fully over the contaminatedarea. Full control will be exerted by the new extraction well sothat the City of Liberty well field will be protected. After thenew extraction well is operational, the contaminant level at WSW2will decline to below MCLs and can be retired from the extractionoperation and return to its normal water supply status.

The groundwater aquifer is expected to meet MCL water qualitystandard within five (5) years after initiating this process at apresent worth cost of $550,000.

Alternative VI:

This alternative is the addition of bioremediation to AlternativeIV once the residual concentration level of Alternative IV isreached. Bioremediation is the enhancement of the activity ofnaturally occurring microorganisms. The introduction of propernutrients to the system will increase their consumption ofcontaminants and will allow an increased population growth ofmicroorganisms. Bioremediation will be implemented using thesame infrastructure of Alternative IV. This alternative, isestimated to require 15 years for site restoration at a presentworth cost of $950,000.

Alternative VII:

This alternative is the addition of bioremediation to AlternativeV once the "residual concentration level of Alternative V isreached. Bioremediation will be implemented using the sameinfrastructure of Alternative V. This alternative is estimatedto require 5 years for site restoration at a present worth costof $640,000.

24

7.1 Applicable or Relevant and Appropriate Requirements fARARs)

The selected remedy will comply with all federal and stateapplicable or relevant and appropriate requirements (ARARs).Applicable requirements are those state or federal requirementslegally applicable to the release or remedial action contemplatedthat specifically address a hazardous substance, pollutant,contaminant, remedial action, location or other circumstancefound at the Site. If it is determined that a requirement is notapplicable, it may still be relevant and appropriate to thecircumstances of the release. Requirements are relevant andappropriate if they address problems or situations sufficientlysimilar to the circumstances of the release or remedial actioncontemplated and are well-suited to the Site.

Numerical values for the chemical-specific ARARs identified forthe Site are listed in Table 7. No federal or state location-specific ARARs were identified for the Site. The major chemical-specific and action-specific ARARs for the Lee Chemical Site arelisted below:

Chemical-specific ARARs

Federal Maximum Contaminant Levels for volatile organics indrinking water supplies (40 CFR Part 141).

- Establishes health-based standards, maximum contaminantlevels (MCLs), for public water systems.

- MCLs for organic contaminants are applicable togroundwater.

State Maximum Volatile Organic Chemical Contaminant Levels forpublic water systems (10 CSR 60-4.100).

- Establishes maximum chemical contaminant levels forvolatile organic chemicals in public water systems.

- Maximum contaminant levels may be applicable togroundwater at the Site. '

Federal Water Quality Criteria (40 CFR Part 131) QualityCriteria for water.

- Establishes criteria for water quality based ontoxicity to aquatic organisms and human health.

- Ambient water quality criteria may be relevantand appropriate for the discharge to Town Branch.

State Water Quality Standards for volatile organics ingroundwater (10 CSR 20-7.031).

- Establishes maximum contaminant levels and monitoringrequirements.

- Requirements may be applicable if more stringent thanfederal requirements.

25

Action-specific ARARs

National Primary and Secondary Ambient Air Quality Standards(40 CFR Part 50).

- Establishes primary (health based) and secondary(welfare based) standards for air quality.

- Standards may be relevant and appropriate to emissionsfrom discharge to Town Branch.

National Pollution Discharge Elimination System (NPDES)(40 CFR Part 125)

- Requires permits for the discharge of pollutantsinto the waters of the United States.

- NPDES permit is in effect for discharge toTown Branch.

f

State Air Quality DeMinimis Emission Levels 10 CSR6.060(7)(A).

- Establishes requirements for new source emissionpermits.

- Requirements may be relevant and appropriate toemissions from discharge to Town Branch.

State Water Quality Standards for Aquatic Life Protection(10 CSR 20-7.031).

\

- Promulgates standards and rules to protect the qualityof lakes and streams.

- Standards and rules may be relevant and appropriate tothe discharge to Town Branch.

SECTION 8.0 SUMMARY OF THE COMPARATIVE ANALYSIS OF ALTERNATIVES

Alternatives were developed to respond to the groundwatercontamination in the aquifer. The alternatives described in thepreceding section were evaluated using evaluation criteriapresented in OSWER Directive 9355.3-02, "Interim Final Guidanceon Preparing Superfund Decision Documents: The Proposed Plan,the Record of Decision, Explanation of Significant Differences,and the Record of Decision Amendment, June 1989" and the NationalOil and Hazardous Substances Pollution Contingency Plan (NCP), 40C.F.R. Part 300. These criteria relate to factors mandated inSection 121 of CERCLA/SARA and consideration of the overallfeasibility and acceptability of the remedy. The nine criteriaare as follows:

t.

Threshold Criteria

Overall Protection of Human Health and Environmentaddresses whether or not a remedy provides adequate protectionand describes how risks through each pathway are eliminated,

26

reduced or controlled through treatment, engineering controls,or institutional controls;

Compliance with Applicable or Relevant arid AppropriateRequirements (ARARs) addresses whether or not a remedy willmeet all of the applicable or relevant and appropriaterequirements of other Federal and State environmental statutesand/or provide grounds for invoking a waiver;

Primary Balancing Criteria

Long-Term Effectiveness and Permanenqe refers to themagnitude of residual risk and the ability of a remedy tomaintain reliable protection of human health and theenvironment over time once cleanup goals have been met;

Reduction of Toxicity, Mobility, or Volume throughTreatment ;Ls the anticipated performance of the treatmenttechnologies that may be employed in a remedy;

Short-Term Effectiveness refers to the speed with whichthe remedy achieves protection, as well as the remedy'spotential to create adverse impacts on human health and theenvironment that may result during the construction andimplementation period;

Implementability is the technical and administrativefeasibility of a remedy, including the availability ofmaterials and services needed to implement the chosensolution;

Cost includes capital and operation and maintenance costs;

Modifying Criteria

State Acceptance indicates whether, based on its review ofthe RI/FS and Proposed Plan, the State concurs with, opposes,or has no comment on the preferred alternative;

- Community Acceptance which is assessed in theResponsiveness Summary which is attached to this Record ofDecision (ROD), and which reviews the public comments receivedduring the public comment period.

Each alternative was evaluated against the specific criteriadescribed above to assess the relative performance of eachalternative. The comparative analysis is summarized below and inTables 8a and 8b:

THRESHOLD CRITERIA

-Overall Protection of Human Health and the Environment;

Alternative I, the no action alternative, will not be protectiveof human health and the environment. The contaminant plume will

27

TABLE 8a. .

Screening of Alluvial Aquifer Alternative!

ALTBWATm IHFUMEirr ABILITY COBT BQKERTM §TA1W

Alternative t

No nation

NJOO

Alternative II

trtendeel pteapla* *t

WO and Liberty

No. 2. DUcnerf.0 to

Town Branch.

Alternative tit

•.•tended pMpiMo ofnew well end Liberty••11 *». S

W-J *n4 LibertyV*. f. Conttroct•oil flaihlnt (rite*.

not pratMt IMBMH ti*«lth•t>4 the envlrorBMnt fraej futurerltk. Toileltr, •obllltr «M velu•( eenUBilnent plane anch«n(»4.

riVM «oald epreed over - larger•ree.

No technologic* |M01*Ment*4.Ho technical ar ednlnletretlvo

feeilbllltr •onclderctlon*.

£*N «0l ••tola •• M««lto4 if UMNC* to Mo*«ro UM •Cfoott•( olket

rroteete huMrt heettk kyeeotealnetlon. Aquifer eontevlnetlcreaedletlon In 23 yeer*.

No no* feellltlee required.Cxiitlnt dlecherge line endperalt to Town Branch In •>!•••.

Capital MS.COflMM IM.MIPresent wctk !««,«

(totalsjtoefcnoletle* In fleeo.

•Mtoet* tioBMi health Vy teewlntcoatoatlnatlon. Aquifer contamination

(reawdlatlon In 23 yean. Inoreaaed|control of pl«a* with oontalnaent•lUiln'tlte.

Conatructlon of new high eepavlty (Capital •17S.OOOveil. Dlicharge line and pervlt ((MM 841.000In place. JPreaent worth ITIT.C

Prote«ta \iimm health by rewrvlng

centealnatIon. Aquifer ftontaailnatlon

reewdletlen In 13 yeari. Inereeaee

rat* at toll aontawlnatlon rewnral.

(Construction of aoll fluthlnt

jayate* required. CH-3. Liberty

(Ho. 1, end dl(charge line In

(place.

I

I

(Retain hoeeoeo mt(Uchnologle* ajkl Mil* Ujpleee.

I

I •

I

Capital I1YS.OOOCMH 84*.000

Prteent worth 6040,1

(••tain| techno locy

I

ofwall* In

TABLE 8b.

Screening, of Alluvial Aquifer Alternative*

ALTOWATtn IHPLEHEItrABtLtTT COST

Att»tn«tlT*

•an«tnntin« •*!!

Prot»«t* haMH h««lth br ftiwlniaant«iln«tl«Mi. tnet*«>»d control

(Conitrtietlon ot n«« high eipceltr |C«plt«l t3>3,000«nd

pcmlt In•C ooll eontiBlnttlon rR«Mdl«tloa In 3 r**r*.

|pUc».

I

|<MM •«. wo|pr«**nt «orth IJM.C

IIII

|*rote«ta nxaan neslth toy rawing )Conetraetlon ot eoll f lushing (Capital IU3.000•ontaaUnatton and addressing realdval jayaten with the addition et JOCM ••t.OOOaoll •onteatnatlon. Ai|ulfer |blore«Mdlatlon. Oroundwater wella |Present wortll S*30.

•all Clachtn* «y*t«i.EW-I nd Llb«ttf Ho. Ila

Alicraitlv* Tit

eontMlnttlMi r«Mdl*tlon In 13

•nd LIMttr Ro. S.conctraet ooll

. nd lntt«dve«

•ontMlmtlon(•oil eantnlnatlon.|eont«BlnBtlo

(••tdu*l

«td dlich*r|* lln* In pl«eo.

Conitruetlon of new til«h capacity (Capital 8413.000MM 831.000Present worth IC40.MO

well and aoll flushing eyeteia are(rellebla technologies. Liberty

In 3 year*, (veil No. 2 end dlseherge lino In

I

(••tain b«ee«ee ofjtMtmloflM Mid oip»41tt4r«0*dl«l MttlOd.

(lUUU fcoaono Ot VOMdUt

|tMtnolofliM !• ytM* andlan «f

la Mil it

(Retain BOOMM ot «nnanaa4

migrate toward the currently uncontaminated municipal wells andpresent future health risks to groundwater users. The existingcontamination in the groundwater already exceeds state andfederal drinking water standards and state water qualitystandards for groundwater.

Alternatives II, III, IV, V, VI and VII will all be equallyprotective of human health and the environment by extracting thecontaminated groundwater. The contaminants will be permanentlyremoved from the groundwater. At the completion of theremediation, the TCE concentration in the aquifer will be reducedto 5 ppb or less, thereby bringing the exposure levels within anacceptable risk range.

- Compliance with ARARs:

Alternative I will not meet ARARs since the contaminantconcentrations will not be reduced. Alternatives II, III, IV, V,VI and VII will meet their respective Applicable or Relevant andAppropriate Requirements (ARARs) of federal and stateenvironmental laws. Specifically, they vill reduce thegroundwater contamination to meet Maximum Contaminant Levels fordrinking water supplies and Missouri water quality standards forgroundwater. No waiver from ARARs is required to implement anyof the active cleanup options. Since Alternative I does not meetthe threshold criteria, it will not be discussed in depth in thefollowing discussion of the other selection criteria.

PRIMARY BALANCING CRITERIA

- Long-term Effectiveness and Permanence;

For Alternative I, the no action alternative, the plume willcontinue to migrate and could eventually contaminate the rest ofthe City of Liberty's water supply wells.

All other Alternatives will involve long term pump and permitteddischarge remedies requiring from 5 to 25 years to complete.Reviews no less than every, five years will be required becausethe remedies will result in hazardous substances remaining onsiteabove health-based levels during the remediation. At thecompletion of the remediation, the groundwater in the aquiferwill be restored for future unrestricted use by reducing the Sitecontaminants to their respective ARAR levels.

All Alternatives, except Alternative I, use discharge under theterms and conditions of an NPDES permit as their means ofultimate removal of the contaminated groundwater. This method iscurrently being used at the Site under the remediation plan nowin effect. None of the Alternatives will produce residuals suchas a sludge. Stringent monitoring to insure the NPDES limits aremet will be required.

30

- Reduction of Toxicity. Mobility,, and Volume;

Alternative I will not reduce the toxicity or mobility of thecontaminants, and the volume of contaminated groundwater willincrease as the plume migrates.

All of the other Alternatives equally reduce the mobility andvolume of the contaminants. All other Alternatives willirreversibly reduce contaminant levels in the soil andgroundwater to levels which satisfy ARARs. Future use of onsiteand offsite groundwater from the aquifer could pose unacceptablehealth risks at present contaminant levels. Dermalcontact/ingestion of onsite groundwater poses the greatest healththreat. The permitted discharge processes employed by all of theAlternatives will reduce the inherent hazards posed by theprincipal threats at the Site.

-Short-term Effectiveness;

Alternatives I and II will not increase short-term risks- to thecommunity, environment, or workers since no constructionactivities are planned.

All other Alternatives provide adequate and approximately equalprotection to the community and workers during construction andimplementation. Alternatives III, V and VII will requireconstruction of an onsite extraction well and Alternatives IVthrough VII will require construction of an in-situ aqueous soilwashing system consisting of infiltration trenches. Any releaseof VOCs during well construction or the construction of the soilwashing system will rapidly disperse and are not likely to pose apublic health risk. The Site perimeter fence and backfillcovering the Site will minimize risks to the community posed byonsite construction of the new extraction well required forAlternatives III, V and VII. The vegetation already covering theSite will minimize dust emissions. Construction of theextraction well will pose normal risks associated with theconstruction of any well.

Drawdown of the aquifer, which is normal during groundwaterextraction, will not create any significant environmental impactsfrom Alternatives II through VII. The increased flow in TownBranch from all Alternatives will not create any significantenvironmental impacts.

- Implementability;

Alternative I does not use any controls or technologies whichwill require coordination with other agencies.

All other Alternatives will involve, long term pump and permitteddischarge remedies requiring from 5 to 25 years to complete andare approximately equal in terms of technical feasibility,administrative feasibility, and availability of services and

31

materials. All of the implementation time frames are based oncontaminant concentration trends as a result of the interimresponse action or sound engineering judgment. Alternative II isslightly more feasible technically and administratively, since itis currently being implemented. None of the remainingAlternatives should be difficult to implement. The services andreguired materials are readily available. The technologies usedin all Alternatives involve tested and widely used processeswhich have proven very effective in removing VOCs fromgroundwater. For all Alternatives except Alternative I, airtoxic regulations may necessitate new air permits for thevolatile organics being volatilized as a result of the NPDESdischarge. Alternative II will require the least coordinationwith MDNR, EPA, and the City of Liberty since no additionalconstruction is planned.

Alternatives III, IV, V, VI and VII will all require additionalconstruction., A NPDES permit will also need to be retained forthe discharge to Town Branch. No permits will be required forsoils remediation under Alternatives IV, V, VI or VII. •

Costs;

Alternative I will have $0 cost.

Alternative II will have an estimated capital cost of $25,000, anestimated annual operation and maintenance (O&M) cost of $56,000,and an estimated implementation time frame of 25 years. Assuminga 10 percent discount rate, the present worth is $814,000.

Alternative III will have an estimated capital cost of $175,000,an estimated annual O&M cost of $42,000, and an implementationtime frame of 25 years. Assuming a 10 percent discount rate, thepresent worth is $767,000.

Alternative IV will have an estimated capital cost of $175,000,an estimated annual O&M cost of $66,000, and an estimatedimplementation time frame of 15 years. Assuming a 10 percentdiscount rate, the present worth is $860,000.

Alternative V will have an estimated capital cost of $325,000, anestimated annual O&M cost of $52,000, and an estimatedimplementation time frame of 5 years. Assuming a 10 percentdiscount rate, the present worth is $550,000.

Alternative VI will have an estimated capital cost of $265,000,an estimated annual O&M cost of $66,000, and an estimatedimplementation time frame of 15 years. Assuming a 10 percentdiscount rate, the present worth is $950,000.

Alternative VII will have an estimated capital cost of $415,000,an estimated annual O&M cost of $52,000, and an estimatedimplementation time frame of 5 years. Assuming a 10 percentdiscount rate, the present worth is $640,000.

32

MODIFYING CRITERIA

- State Acceptance;

Representing the State of Missouri, the MDNR selected AlternativeV in the Proposed Plan as its preferred alternative. The Stateis the lead agency for this Site. However, under the Superfundlaw, it is the EPA which must make the decision, in consultationwith the State, on what the final remedy will be. MDNR hasconcurred with EPA's final remedy selection.

- Community Acceptance:

The reservations, concerns, and supporting or opposing commentsof the community on the RI/FS, the Proposed Plan, and otherinformation in the Administrative Record were made known to theMDNR and EPA during the thirty day comment period and the publichearing with the community on January 9, 1991. The public'scomments are addressed in the Responsiveness Summary, which is acomponent of this Record of Decision for the Site.

8.1 Conclusion on the Comparative Analysis

All Alternatives, except .Alternative J, the no-actionAlternative, meet the threshold criteria. All of these otherAlternatives are substantially equivalent under the balancingcriteria of the long-term effectiveness and permanence, thereduction of toxicity, mobility and volume, and the short-termeffectiveness. With respect to the balancing criteria ofimplementability, all of these Alternatives are substantiallyequivalent, except that the estimated implementation time framefor Alternatives V and VII are substantially shorter, estimatedat 5 years. Also, with respect to the balancing criteria ofcosts, Alternatives V and VII are the two lowest costalternatives that also meet the threshold criteria. AlternativeV, the lowest cost alternative, which is also one of the twoalternatives with the lowest implementation time frames, istherefore the most cost effective alternative. Additionally,Alternative V has been accepted by the State of Missouri as itspreferred alternative and the responsiveness summary showscommunity acceptance of Alternative V.

SECTION 9.0 THE SELECTED REMEDY

Based upon consideration of the requirements of CERCLA, thedetailed analysis of the alternatives, and public comments, boththe EPA and the State of Missouri have determined thatAlternative V, installation of an extraction well and an in-situaqueous soil washing system, discharge under the terms andconditions of a NPDES permit to Town Branch Creek; is the mostappropriate remedy for -the "Lee "Chemical—Srte ±n "Liberty,Missouri. This remedy is an enhancement of the ongoing interimresponse action (Alternative II) at the Site as described inSections 2.2 and 5.0. In the event that additional treatment <of

33

the discharge water becomes necessary to meet either the NPDESpermit limits or other applicable or relevant and appropriaterequirements, a contingency phase project consisting of airstripping or other treatment methods will be implemented to bringthe discharge into compliance.

The selected remedy will transfer the VOCs from the subsurfacesoils and groundwater to surface water as well as to the air asvolatiles are off-gassed during the discharge process. Airmodeling predicts that the potential cancer risk and the hazardindex ratios of airborne VOCs from the discharge are acceptable.However, continued ambient air monitoring will be required as apart of this Site remediation.

The extraction system for Alternative V consists of using oneexisting and one new well for the remediation. These extractionwells, WSW2 and the .new onsite well, will be used for collectionof contaminated groundwater from the aquifer. Several otherwells, both on and offsite, are available for use as extractionwells, should they be needed.

However, it is not anticipated that any other wells will beneeded unless the plume of contamination spreads beyond theexisting known areas of contamination. The new onsite extractionwell will be constructed in the southeast corner of the property.The exact well design and location will be determined duringremedial design. A well design similar to a normal water supplywell would accomplish the remedial objectives and could beutilized as a future supply well for the City of Liberty onceremediation is complete.

The current site conditions indicate that a pumping rate of 1,000to 1,300 gallons per minute is controlling groundwater flow andis limiting contamination in the well field to only WSW2. Theremedial pumping rate may need to be modified as other factorsinfluencing the aquifer are identified. The actual pumping raterequired will be based on the evaluation of conditions as theremediation gets underway. It is anticipated that the new onsiteextraction well will effectively produce a hydraulic barrier thatwill prevent further contaminant migration from the Site.

Contaminated groundwater from both extraction wells .will be pipedthrough the existing discharge system to Town Branch Creek. Ifthe TCE level in the groundwater extracted from these wells isfound to exceed the discharge limitations set forth in the NPDESpermit or if ambient air monitoring indicates an unacceptablehealth risk resulting from air emissions at the point ofdischarge, then it will be necessary to invoke the contingencyphase of this project consisting of further treatment prior todischarge. Periodic monitoring of ambient air quality along withwater quality monitoring, in accordance with the NPDES permit,will be performed. 'If needed, the additional treatment willremove the volatile organic contaminants from the groundwater.

34

An existing pipeline will carry the extracted groundwater fromthe Site to Town Branch Creek, where additional aeration andmixing occurs as the water flows down over riprap to the creekproper. The discharge operates under a state NPDES permit whichstipulates a TCE monthly average discharge limit of 1,000 ug/1.Subsurface soil contamination at the Site, further contributingto the groundwater contamination, is to be addressed by theinstallation of a series of parallel trenches to be located abovethe contaminated soil on the Lee Chemical Site. Uncontaminatedraw water from the City's well field will be utilized to floodthese trenches, allowing water to saturate the contaminated soilsbelow and thereby flushing contaminants 'to the groundwater tosubsequently be picked up by the groundwater extraction system.The number and depth of the trenches and the operationalparameters will be determined during the remedial design andmodified as site conditions warrant once actual remediationbegins.

The estimated capital cost of the remedy is $325,000, with annualO&M costs estimated to be $52,000. Assuming a 5 year operationand a 10% discount rate, the present worth is $550/000. Somechanges may be made to the remedy as a result of the remedialdesign and construction processes, thereby affecting theestimated costs. Such changes, in general, reflect modificationsresulting from the engineering design process or the use of thecontingency phase air stripper. For the air stripper, anadditional capital cost of $50,000 has been estimated, withannual O&M costs estimated at $15,000. Assuming a 5 yearoperation and a 10% discount rate, the present worth isapproximately $120,000 for this contingency phase.

9.1 Remediation Goals

The purpose of this response action is to prevent potentialexposure to contaminated groundwater; protect uncontaminatedgroundwater for future use by preventing further migration of thecontaminated groundwater plume; restore the contaminated aquiferfor future use as a drinking water source by reducing thecontaminant concentrations, to regulated or health-based levels,for example, 5 ppb or less for TCE, and remediate contaminatedsoils onsite such that no further groundwater contamination withVOCs above action levels can occur. Existing conditions at theSite have been determined to pose an excess lifetime cancer riskas high as 2 X 10" . The lifetime non-carcinogenic risk fromexposure to site contaminants is insignificant. These risksrelate to the VOC concentrations in groundwater which were foundto be as high as 130 ug/1 during the RI.

The acceptable exposure levels at this site that are protectiveof human health and the environment were developed by consideringthe ARARs identified in Section 10.2. Attainment of the chemicalspecific ARARs will result in cumulative carcinogenic risks atthe Site within the acceptable 10~4 to 10~6 risk range forcarcinogens, considering all contaminants and exposure pathwaysat the Site.

35

SECTION 10.0 STATUTORY DETERMINATIONS

Under its legal authorities, EPA's primary responsibility atSuperfund sites is to undertake remedial actions that achieveadequate protection of human health and the environment. Inaddition, Section 121 of CERCLA establishes several otherstatutory requirements and preferences. These specify that whencomplete, the selected remedial action for this site must complywith applicable or relevant and appropriate environmentalstandards established under Federal and State environmental lawsunless a statutory waiver is justified. The selected remedy alsomust be cost effective and utilize permanent solutions andalternative treatment technologies or resource recoverytechnologies to the maximum extent practicable. Finally, thestatute includes a preference for remedies that employ treatmentthat permanently and significantly reduce the volume, toxicity,or mobility of hazardous substances as their principal element.The following,subsections discuss how the selected remedy meetsthese statutory requirements.

10.1 Protection of Human Health and the Environment

The selected remedy protects human health and the environmentthrough extraction of the VOC-contaminated groundwater. Thecontaminants will be permanently removed from onsite soils andthe groundwater. Extraction of the VOC-contaminated groundwaterand remediation of contaminated site soils will eliminate thethreat of exposure to the most mobile contaminants at the Site.The current carcinogenic risks associated with the exposurepathways identified in the risk assessment are as high as2 X 10~4. The selected remedy will reduce the cancer risks atthe Site to within the acceptable 10 to 10 risk range forcarcinogens, and the Hazard Index for non-carcinogens will beless than one. There are no unacceptable short-term threatsassociated with the selected remedy that cannot be readilycontrolled. In addition, no adverse cross-media impacts areexpected from the remedy.

10.2 Compliance Applicable or Relevant and AppropriateRequirements (ARARs)

The selected remedy will comply with all federal and stateapplicable or relevant and appropriate requirements (ARARs).Applicable requirements are those state or federal requirementslegally applicable to the release or remedial action contemplatedthat specifically address a hazardous substance, pollutant,contaminant, remedial action, location or other circumstancefound at the Site. If it is determined that a requirement is notapplicable, it may still be relevant and appropriate to thecircumstances of the release. Requirements are relevant andappropriate if they address problems or situations sufficientlysimilar to the circumstances of the release or remedial actioncontemplated and are well-suited to the Site.

36

Numerical values for the chemical-specific ARARs identified forthe Site are listed in Table 7. No federal or state location-specific ARARs were identified for the Site. The major chemical-specific and action-specific ARARs for the Lee Chemical Site arelisted below:

Chemical-specific ARARs

Federal Maximum Contaminant Levels for volatile organics indrinking water supplies (40 CFR Part 1.41) .

- Establishes health-based standards, maximum contaminantlevels (MCLs), for public water systems.

- MCLs for organic contaminants are applicable togroundwater.

State Maximum Volatile Organic Chemical Contaminant Levels forpublic water systems (10 CSR 60-4.100).

- Establishes maximum chemical contaminant levels forvolatile organic chemicals in public water systems.

- Maximum contaminant levels may be applicable togroundwater at the Site.

Federal Water Quality Criteria (40 CFR Part 131) QualityCriteria for water.

- Establishes criteria for water quality based ontoxicity to aquatic organisms and human health.

- Ambient water quality criteria may be relevantand appropriate for the discharge to Town Branch.

State Water Quality Standards for volatile organics ingroundwater (10 CSR 20-7.031).

- Establishes maximum contaminant levels and monitoringrequirements.

- Requirements may be applicable if more stringent thanfederal requirements.

Action-specific ARARs

National Primary and Secondary Ambient Air Quality Standards(40 CFR Part 50).

- Establishes primary (health based) and secondary(welfare based) standards for air quality.

- Standards may be relevant and appropriate to emissionsfrom discharge to Town Branch.

National Pollution Discharge Elimination System (NPDES)(40 CFR Part 125)

- Requires permits for the discharge of pollutantsinto the waters of the United States.

37

- NPDES permit is in effect for discharge toTown Branch.

State Air Quality DeMinimis Emission Levels 10 CSR6.060(7)(A).

- Establishes requirements for new source emissionpermits.

- Requirements may be relevant and appropriate toemissions from discharge to Town Branch.

State Water Quality Standards for Aquatic Life Protection(10 CSR 20-7.031).

- Promulgates standards and rules to protect the qualityof lakes and streams.

- Standards and rules may be relevant and appropriate tothe discharge to Town Branch.

10.3 Cost Effectiveness

The selected remedy is cost effective because it has beendetermined to provide overall effectiveness proportional to itscosts, the net present worth value being $550,000.

10.4 Utilization of Permanent Solutions and Alternative TreatmentTechnologies to the .Maximum Extent Practicable

The State of Missouri and EPA have determined that the selectedremedy represents the maximum extent to which permanent solutionsand treatment technologies can be utilized in a cost effectivemanner for the Lee Chemical Site. Of those Alternatives that areprotective of human health and the environment and comply withARARs, the State of Missouri and EPA have determined that thisselected remedy provides the best balance of trade-offs in termsof long-term effectiveness and permanence, reduction in toxicity,mobility, or volume achieved through treatment, short-termeffectiveness, implementability, cost, also considering thestatutory preference for treatment as a principal element andconsidering State and community input.

Alternative V reduces the toxicity, mobility, and volume of thecontaminants in the groundwater and soil; complies with ARARs;provides short-term effectiveness; and protects human health andthe environment equally as well as all other Alternatives, interms of implementability, Alternative V is more reliable thanother Alternatives because the combination of a new extractionwell and soil washing system should result in a much quickerremoval of the contamination thus helping to prevent furthermigration of the contaminants. Alternative V will be easy toimplement technically because it requires only normalconstruction activities and administratively because it willrequire little additional coordination with relevant agencies.The major trade-offs that provide the basis for this selectiondecision are implementability and cost effectiveness. The

38

selected remedy is an enhancement of the interim response actioncurrently operating at the Site and thus is known to be reliable.The basic improvements to the existing process provided for inAlternative V can be implemented quickly and with more confidencethat they will protect the City's remaining water supply wellsfrom contamination. Therefore, Alternative V is the mostappropriate permanent solution for the contaminated soil andgroundwater at the Lee Chemical Site. /

10.5 Preference for Treatment as a Principal Element

The selected remedy removes the VOC contamination from the soilsat the Site as well as capturing and removing contaminatedgroundwater. Thus, the selected ifemedy addresses the principalthreats posed by the Site through the use of proven treatmentmethods. Therefore, the statutory preference for remedies thatemploy treatment as a principal element is satisfied. Thecontingency phase project for additional treatment of theextracted groundwater also incorporates treatment as a principalelement. •

SECTION 11.0 DOCUMENTATION OF SIGNIFICANT DIFFERENCES

No significant changes were made to the recommended alternativein the Proposed Plan.

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RECORD OF DECISION

THE RESPONSIVENESS SUMMARY

LEE CHEMICAL SITE

LIBERTY, MISSOURI

Prepared By:




. And


Region VII

Kansas City, Kansas

March 1991

RESPONSIVENESS SUMMARY

TABLE OF CONTENTS

SECTION PAGE

1. 0 OVERVIEW 1

2 . 0 BACKGROUND ON COMMUNITY INVOLVEMENT 1

3.0 SUMMARY OF COMMENTS RECEIVED DURINGPUBLIC COMMENT PERIOD 2

LEE CHEMICAL SITELIBERTY, MISSOURI

RESPONSIVENESS SUMMARY

SECTION 1.0 OVERVIEW

In the Proposed Plan released to the public, the MissouriDepartment of Natural Resources (MDNR), with U.S. EnvironmentalProtection Agency concurrence, made a preliminary selection forthe preferred Alternative. MDNR's recommended Alternativeaddressed the groundwater and soil contamination problem at theSite. The preferred alternative involved extraction andcontainment of the contaminant plume using existing and newwells, implementing an in-situ aqueous soil washing systemconsisting of' infiltration trenches to enhance the flushing ofcontaminants from Site soils, and discharge of the purgedgroundwater to Town Branch Creek under the terms and conditionsof a NPDES permit.

In the event that additional treatment of the discharge waterbecomes necessary to meet either the NPDES permit limits or otherapplicable or relevant and appropriate requirements, acontingency phase project consisting of air stripping or othertreatment methods will be implemented to bring the discharge intocompliance.

No comments were received during the public comment periodopposing the preferred alternative as presented. One Libertyresident asked for an analysis of the effects of1,1,2-trichloroethene (TCE) on Town Branch and Shoal Creeks andthe possibility of bioaccumulation occurring. This resident alsoasked what the impacts resulting from the release of TCE into theair, either through the outfall from the wells or through an airstripper if required, will have on the people who work down inthe bottoms near the Site..

The Potentially Responsible Party supported the preferredAlternative as described in the Proposed Plan.

SECTION 2.0 BACKGROUND ON COMMUNITY INVOLVEMENT

Community interest in the Site dates back to 1979 whencontamination of the public water supply wells in Liberty wasfirst discovered. The major issues expressed at that time wereconcerned with providing the community with a safe drinking watersupply. This issue was addressed by the interim response actiontaken by the City of Liberty which effectively returned levels ofTCE in the public water supply to below levels of concern. TheRI/FS process was performed with regular, reports to the CityCouncil on its progress and findings.

The public comment period on the preferred Alternative asoutlined in the Proposed Plan began on December 24, 1990 andended January 23, 1991. A public hearing was held in Liberty onJanuary 9, 1991. The responsiveness summary addresses commentsreceived during this period.

SECTION 3.0 SUMMARY OF COMMENTS RECEIVED DURING PUBLIC COMMENTPERIOD

Comments received during the public comment period on theRemedial Investigation, Feasibility Study, and Proposed Plan forthe Lee Chemical Site are briefly summarized below. Only twocomments were received.

Question 1./

Considering that purged groundwater has been discharged intoTown Branch Creek for several years, has anyone looked at theeffects of the TCE on the creek itself, i.e., buildup in thesediment or the benthic organisms (the organisms living on thecreek bottoms) or anything of that nature?

MDNR/EPA Response;

There have been no samples of sediments or of the organismsliving on the creek bottoms collected/analyzed from Town Branchor Shoal Creek to date. There have been in-stream water qualitysamples collected at the confluence of Town Branch and ShoalCreek none of which showed significant concentrations of TCE.

Laboratory studies have demonstrated that TCE volatilizesrapidly from water. Although volatilization is rapid, actualvolatilization rates are dependent upon temperature, watermovement and depth, associated air movement, and other factors.Because neither biodegradation nor other fate processes occur ata rapid rate, most TCE present in surface waters can be expectedto volatilize into the atmosphere.

The biological process of bioaccumulation is generallyreported in terms of a bioconcentration factor (BCF), the ratioof the concentration of a substance in a living organism to theequilibrium concentration in the medium in which the organismlives. Bioconcentration factors reported in the literaturegenerally range from one to one million. Experimental BCF datameasuring TCE concentrations in fish, seawater, and associatedaquatic organisms supports a low bioaccumulation potential forbenthic organisms (i.e. BCF of 17 in fish). Although evidence ofbioaccumulation potential exists, the process for TCE is probablynot important in comparison to other removal mechanisms, such asvolatilization.

The level of TCE concentrations entering Town Branch at theoutfall has consistently been below 90 parts per billion (ppb)since the RI commenced. Based on that data, it would appearthere is an almost complete volatilization of the TCE in thewater between the point of discharge and the confluence of ShoalCreek (approximately 1600 feet).

However, in response to this concern, MDNR will furtherinvestigate the need to sample and analyze the creek sedimentsand benthic organisms for TCE bioaccumulation.

Question 2.

What are the air impacts of TCE being released, either throughthe outfall from the wells or an air stripper if implemented, onpeople who work in the bottoms near the Site?

MDNR/EPA RESPONSE:•

As part of the Risk Evaluation prepared for the Lee ChemicalSite, inhalation of VOCs by residents and industrial workersdownwind of the extraction well discharge point on Town Branchwas examined. • "

The purged water flows through a discharge line to Town Branchwhere it continues over a dispersion plate and then cascades downthe embankment approximately 20 to 30 feet over riprap and entersthe Town Branch. Although the VOCs in this water will partiallyvolatilize and potentially expose those downwind of the dischargepoint, we studied the exposure of workers and residents closestto the Site and found negligible risks. The extent of exposurewas calculated based on employees working at the closest facilityto the discharge point (100 yards) and on the closest permanentresidents (200 yards), because they would have the potential forthe highest exposure duration.

Should discharge concentrations increase to levels that wouldrepresent a significant risk to resident and worker populations,monitoring of ambient air quality will be performed to verifythese risks. If this monitoring indicates that an unacceptablehealth risk is resulting from air emissions at the point ofdischarge, it will then be necessary to invoke the contingencyphase of this project consisting of further treatment prior todischarge.

RECORD OF DECISION FOR THE LEE CHEMICAL SITE · Water Supply Wells Number 1 through 7 (WSW1 through...

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