RECORD OF DECISION

VERTAC SUPERFUND SITEJACKSONVILLE. ARKANSAS

OPERABLE UNIT 2SOILS, FOUNDATIONS AND UNDERGROUND UTILITIES

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

DECEMBER 1995

RECORD OF DECISIONCONCURRENCE DOCUMENTATION

FOR THEVERTAC SUPERFDND SITE

OPERABLE UNIT 2JACKSONVILLE, ARKANSAS

Richard Ehrhart, Site Remedial Project ManagerSuperfund Division

John Dugdale, Site AttorneySuperfund Litigation and Enforcement Branch

Mark Peycke, ChiefSuperfund Litigation and Enforcement Branch

Wren Stenger, ChiefArkansas/Oklahoma Section 6SF-AO

William K. Honker, ChiefSuperfund Ar/Ok/Tx Branch

Pam Phillips, DeputySuperfund Division

Myron 0. Knudson, P . E . , DirectorSuperfund Division

DECLARATIONVERTAC SUPERFUND SITERECORD OF DECISIONOPERABLE UNIT 2DECEMBER 1995

SITE NAME AND LOCATIONVertac IncorporatedJacksonville, ArkansasSTATEMENT OF BASIS AND PURPOSE

This decision document presents the selected remedial actionfor Operable Unit 2 , Soils, Foundations and UndergroundUtilities, for the Vertac, Incorporated, site in Jacksonville,Arkansas. The Environmental Protection Agency (EPA) has selectedthis remedy in accordance with the Comprehensive EnvironmentalResponse, Compensation and Liability Act of 1980 (CERCLA), asamended by the Superfund Attachments and Reauthorization Act of1986 (SARA), 42 U . S . C . § 9601 et s e q . . and, to the extentpracticable, the National Oil and Hazardous Substances PollutionContingency Plan ( N C P ) , 40 CFR Part 300. This decision is basedon the administrative record file for this site.

The State of Arkansas' comments on the selected remedy canbe found in Appendix C.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 ( R O D ) , may present animminent and substantial endangerment to public health, welfare,or the environment.DESCRIPTION OF THE SELECTED REMEDY

There are six operable units for the Vertac site. ThisRecord of Decision addresses the remediation of dioxin andherbicide-contaminated soils, sediments, and sludges from bothon-site and off-site locations, the remediation of on-siteunderground utility lines and tanks, and the remediation of on-site building foundations and curbs.

The remedy for Operable Unit 2 will result in the site beingdivided roughly into two 100 acre tracts. The northern 100 acretract was never a part of the industrial operations at Vertac,and as such, will be remediated so that it can potentially bereturned to commercial/industrial use. Under this remedy, thesouthern 100 acres of the site will remain mostly fenced and

C^ wss will be restricted to on-site maintenance workers because j^.itaminants will remain in place under a soil cap after ^Q

'remediation that will prevent future commercial redevelopment. 05Other site factors that impelled EPA to evaluate a restricted oaccess land use scenario for the southern 100 included: 1) The < »presence of several existing waste disposal areas on this part of <the property that were capped as part of an earlier 1984 Court-ordered remedy; 2) The ROD for Operable Unit 1 requires that allabove ground structures be demolished and placed into an onsiteRCRA Subtitle-C landfill; and 3 ) , This portion of the site willrequire long term ground water control. Access to this part ofthe site is necessary for the purpose of maintaining the wasteburial areas, ground water wells, and ground water treatmentfacility.Inside the Restricted Fenced AreaSoils. Sediments and Sludges• Excavation of dioxin-contaminated surface soils greater than

1,000 ppb (expressed as 2 , 3 , 7 , 8 TCDD toxicity equivalents orTEQ) , and consolidation into an on-site RCRA Subtitle-Chazardous waste containment vault. Excavated areas will bebackfilled with a minimum of one foot of clean fill, graded,and a vegetative cover will be established.

• In-place capping of all dioxin-contaminated soils between 5ppb and 1,000 ppb TEQ with a minimum of 1 foot of clean soilcover. Areas that are capped in place will be graded and avegetative cover will be established.

• Crystalline tetrachlorobenzene (TCB) and soils contaminatedwith TCB from an on-site rail car spill will be excavatedwhere the concentration exceeds 500 ppm and taken off-sitefor disposal at a permitted hazardous waste treatmentfacility.

• Bagged dioxin-containing soils that were excavated fromresidential yards in 1988 as a part of a removal will beconsolidated into the on-site RCRA Subtitle-C landfill.

• Soils with dioxin concentrations greater than 1 ppb TEQ willbe excavated from the residential portion of Bayou Meto andRocky Branch Creek and consolidated in the on-site RCRASubtitle-C landfill.

• Sludges from the off-site abandoned sewage treatment plantwill be consolidated into the on-site RCRA Subtitle-Clandfill.

Underground Utility Lines. Underground Tanks. BuildingFoundations and Curbed Areas• Underground utility lines will be cleaned to remove solids

^'^'•{^ and filled with grout. Solids from the lines will be placed < 1V into the on-site RCRA Subtitle-C landfill. Cuttoff barriers I>*

will be installed around various underground utility lines s—to prevent shallow water migration and contaminant transport —along the lines. °

• Underground storage tanks will be drained and the material ,recycled or incinerated off-site. Tanks will either beclosed in place or removed and disposed of in the on-siteRCRA Subtitle-C landfill.

• Building foundations and curbed areas will be cleanedthrough hydroblasting and scarification and left in place.Areas with persistent staining will be sealed with epoxy"type sealants.

Outside the Fenced AreaSoils• Excavation of dioxin-contaminated surface soils greater than

1 ppb TEQ, and consolidation into an on-site RCRA Subtitle-Clandfill. Excavated areas will be backfilled with cleansoil, graded, and a vegetative cover will be established.

Underground Utility Lines. Building Foundations and Curbed Areas• Underground utility lines will be cleaned to remove solids

and filled with grout. Solids from the lines will be placedinto the on-site RCRA Subtitle-C landfill. Cuttoff barrierswill be installed around various underground utility linesto prevent shallow water migration and contaminant transportalong the lines.

• Building foundations and curbed areas will be cleanedthrough hydroblasting and scarification and left in place.Areas with persistent staining will be sealed with epoxy-type sealants.

STATUTORY DETERMINATIONSThe selected remedy is protective of human health and theenvironment, complies with Federal and State requirements thatare legally applicable or relevant and appropriate to the

remedial action, and is cost effective. This remedy utilizespermanent solutions and alternative treatment technologies, tothe maximum extent practicable, and satisfies the statutorypreference for remedies that employ treatment that reducestoxicity, mobility, or volume as a principle element. Becausethis remedy will result in the capping and landfilling ofcontaminated soils, hazardous substances will remain at the siteabove levels that will allow for unlimited use and unrestrictedexposure. EPA shall review the remedial action no less thanevery five years after initiation of the selected remedial action

to ensure that the remedy continues to provide adequateprotection of human health and the environment.

Jane N. SaginawRegional AdministratorU . S . EPA - Region 6

Date

THE DECISION SUMMARYVERTAC OPERABLE UNIT 2 MEDIA

JACKSONVILLE, ARKANSASDECEMBER 1995

^f-.. :--: vI '• %^ T>»V •^ TABLE OF CONTENTS £,

\^ '' '1.0 SITE LOCATION AND DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . 1 <D

2 . 0 SITE HISTORY AND ENFORCEMENT ACTIVITIES . . . . . . . . . . . . . . . . 4 °2 . 1 Site Operations History . . . . . . . . . . . . . . . . . . . . . . . . . . 42. 2 Enforcement Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3 . 0 HIGHLIGHTS OF COMMUNITY PARTICIPATION . . . . . . . . . . . . . . . . 10

4.0 SCOPE AND ROLE OF OPERABLE UNIT . . . . . . . . . . . . . . . . . . . . . . 11

5 . 0 SUMMARY OF SITE CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . 165 . 1 Demography and Land Use in the Area of the Site . . 165 . 2 Soils and Geology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

5 . 2 . 1 Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185 . 2 . 2 Geology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

5 . 3 Hydrology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 . 3 . 1 Surface Water . . . . . . . . . . . . . . . . . . . . . . . . . 215 . 3 . 2 Ground Water . . . . . . . . . . . . . . . . . . . . . . . . . . 22

5. 4 Remedial Investigation Findings . . . . . . . . . . . . . . . . . 225 . 4 . 1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 . 4 . 2 Sampling Results for Surface Soils . . . . 265 . 4 . 3 Subsurface Soils . . . . . . . . . . . . . . . . . . . . . . 315 . 4 . 4 Tetrachlorobenzene Spill Area . . . . . . . . . 325 . 4 . 5 Underground Utilities . . . . . . . . . . . . . . . . . 325 . 4 . 6 Underground Storage Tanks . . . . . . . . . . . . . 335 . 4 . 7 Off site Rocky Branch Creek and Bayou

Meto Flood Plain Soils . . . . . . . . . . . 335 . 4 . 8 Residential Bagged Soils . . . . . . . . . . . . . . 345 . 4 . 9 Sludges and Sediments from Old Sewage

Treatment Plant Digester . . . . . . . . . 346 . 0 SUMMARY OF SITE RISKS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

6 . 1 Risk Assessment Description . . . . . . . . . . . . . . . . . . . . . 346 . 2 Identification of Chemicals of Concern . . . . . . . . . . 356 . 3 Human Health'Risk Assessment . . . . . . . . . . . . . . . . . . . . 36

6 . 3 . 1 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 366 . 3 . 2 Exposure Assessment . . . . . . . . . . . . . . . . . . . 366 . 3 . 3 Toxicity Assessment . . . . . . . . . . . . . . . . . . . 436 . 3 . 4 Risk Characterization . . . . . . . . . . . . . . . . . 616 . 3 . 5 Uncertainty Analysis . . . . . . . . . . . . . . . . . . 6 96 . 3 . 6 Central Tendency Exposure . . . . . . . . . . . . . 6 9

6 . 4 Ecological Risk Assessment . . . . . . . . . . . . . . . . . . . . . . 716 . 5 Remedial Action Goals . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

7 . 0 DESCRIPTIONS OF ALTERNATIVES . . . . . . . . . . . . . . . . . . . . . . . . . 797 . 1 Alternatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 797.2 ARARs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

7 . 2 . 1 Federal ARARs . . . . . . . . . . . . . . . . . . . . . . . . . 987 . 2 . 2 State ARARs . . . . . . . . . . . . . . . . . . . . . . . . . . 1147 . 2 . 3 To-Be-Considered . . . . . . . . . . . . . . . . . . . . . 120

008 . 0 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES . . . . . 120 ^8 . 1 Comparative Analysis of Remedial Alternatives . . 123 ^

<M9 . 0 THE SELECTED REMEDY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 Q9 . 1 Soils and Sediment Media . . . . . . . . . . . . . . . . . . . . . . . 128 ^9 . 2 Underground Utilities and Tanks . . . . . . . . . . . . . . . . 130 . .

i10. STATUTORY DETERMINATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

10.1 Protection of Human Health and the Environment . . 13110.2 Compliance with ARARs . . . . . . . . . . . . . . . . . . . . . . . . . . 13210.3 Cost Effectiveness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13310.4 Utilization of Permanent Solutions and

Alternative Treatment Technologies . . . . . . . . 13410.5 Preference for Treatment . . . . . . . . . . . . . . . . . . . . . . . 134

11.0 DOCUMENTATION OF SIGNIFICANT CHANGES . . . . . . . . . . . . . . . . 135

05AFT rLIST OF FIGURES SO1 Site Location Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 ^2 Vertac Site Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 w3 Land Use Zoning Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174 Geologic Map of Jacksonville Area . . . . . . . . . . . . . . . . 205 Remedial Actions Performed at the Site . . . . . . . . . . . 236 Vertac Site Process Areas . . . . . . . . . . . . . . . . . . . . . . . . 257 Early Sampling Grids at Vertac . . . . . . . . . . . . . . . . . . . 278 Sampling Grids in the Central Process Plant Area . . 289 Sampling Grids Outside Central Process Plant Area . 2910 Conceptual Model of Exposure Pathways . . . . . . . . . . . . 4411 Conceptual Diagram of Soil Cover . . . . . . . . . . . . . . . . . 8412 Conceptual Model of Subtitle-C Landfill . . . . . . . . . . 8513 Map Depicting Fenced (Restricted Access) Area of

the Site and Area where Access will beUnrestricted . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129

DRAFT 000<^5LIST OF TABLES

General Geologic Section for Site . . . . . . . . . . . . . . . . . . 19 CQSite Contaminants of Concern . . . . . . . . . . . . . . . . . . . . . . 30 0Contaminates of Concern in Soil . . . . . . . . . . . . . . . . . . . 37 t—1Contaminants of Concern in Ground Water . . . . . . . . . . . . 38 * 'Contaminants of Concern in Surface Water . . . . . . . . . . 40 'Model for Calculating Dose - Soil Ingestion . . . . . . . 45Model for Calculating Dose - Dermal Absorption . . . . 46Model for Calculating Dose - Soil Inhalation . . . . . . 48Model for Calculating Dose - Vapor Inhalation . . . . . 50Model for Calculating Dose - Surface Water Dermal . . 51Model for Calculating Dose - Ground Water Ingestion 53Categorization of Carcinogenic Substances . . . . . . . . . 55Cancer Slope Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56Chronic Reference Doses . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57Subchronic Reference Doses . . . . . . . . . . . . . . . . . . . . . . . . . 59Potential Lifetime Cancer Risk - Trespasser . . . . . . . 62Potential Lifetime Cancer Risk - Current Worker . . . . 63Potential Lifetime Cancer Risk - Future Worker . . . . 64Hazard Quotient/Index - Trespasser . . . . . . . . . . . . . . . . 6 6Hazard Quotient/Index - Current Worker . . . . . . . . . . . . 67Hazard Quotient/Index - Future Worker . . . . . . . . . . . . . 68Central Tendency - Cancer Risk/Hazard Indices . . . . . 70Parameters Used in RME Risk Calculations . . . . . . . . . . 74Parameters Used in Monte Carlo Risk Calculations . . . 75Comparison of RME and Monte Carlo Risk Calculations 77Remediation Goals for Contaminated Soils . . . . . . . . . . 78Summary of Soils Alternatives . . . . . . . . . . . . . . . . . . . . . 80Quantities of Materials for Soils Alternatives . . . . 81Summary of Underground Utilities Alternatives . . . . . 93Potential ARARs for the Vertac Site . . . . . . . . . . . . . . . 97

LIST OF APPENDICES

Appendix A - Responsiveness SummaryAppendix B - Administrative Record IndexAppendix C - Arkansas Department of Pollution Control and

Ecology Comments

Vertac Superfund SiteOperable Unit 2Decision Summary

1 . 0 SITE LOCATION AND DESCRIPTIONThe Vertac Incorporated Superfund Site (the " s i t e " ) is

approximately 192 acres in size, and is located on Marshall Roadin Jacksonville, Pulaski County, Arkansas as shown in Figure 1.Jacksonville is about 15 miles northwest of the State Capital,Little Rock. Approximately 1,000 residents live within one mileof the site with residential areas bordering the entire east andsouth sides. The west and northern sides of the site are boundedby an industrial area and the Little Rock Air Force Base.

The site consists of two parcels of land (Parcel 1 andParcel 2) that were acquired at different times during plantoperations (Figure 2 ) . Parcel 1, which contains the centralprocess area, is approximately 93 acres and has been in nearlycontinuous industrial use since 1948. Parcel 2 which isapproximately 100 additional acres to the north, was purchased byVertac in 1978 but was never used in the herbicides formulationsoperation. In 1 9 7 9 , the 2 , 4 , 5 - T storage shed was built adjacentto the Regina paint building, which today is believed to containempty Vertac 2 , 4 , 5 - T waste drums. Parcel 2 does not containproduction facilities and is currently used by the United StatesEnvironmental Protection Agency (EPA) for drum storage in newlyconstructed warehouse buildings. An incinerator constructedunder the contract to the Arkansas Department of PollutionControl and Ecology (ADPC&E) to burn drummed waste is alsolocated in the northern part of Parcel 1.

Topographically, the land has moderate relief, sloping fromabout 310 feet above mean sea level (MSL) in the north toapproximately 260 feet near the southwestern corner. The centralprocess area is located on a south plunging topographic nosebounded by Rocky Branch Creek on the west and Marshall Road onthe east. Land on the western side of Rocky Branch Creek has notbeen used for manufacturing or disposal and is topographicallyseparated from the central process plant area by the creek.Land on the eastern side of Marshall Road has not been used formanufacturing and is geographically separated from the centralprocess plant area by Marshall Road. Land on the northern partof the site has not been used for herbicide manufacture and isgenerally up slope from the central process plant area.

SITE LOCATION MAP. VERTAC SITEJACKSONVILLE, ARKANSAS

FIGURE 1

SITE MAP, VEBTAC SITEJACKSONVILLE, ARKANSAS

C02684

2 . 0 SITE HISTORY AND ENFORCEMENT ACTIVITIES

2 . 1 SITE OPERATIONS HISTORY

The first facilities on the site were constructed by theU . S . Government in the 1930s and 1940s. These facilities werepart of a munitions complex that extended beyond the present siteboundaries. Little is known about the operations that occurredduring that time period. In 1948, the Reasor-Hill Companypurchased the property and converted the operations tomanufacture insecticides such as DDT, aldrin, dieldrin, andtoxaphene. During the 1950s, Reasor-Hill manufactured herbicidessuch as 2,4-dichlorophenoxyacetic acid ( 2 , 4 - D ) , 2 , 4 , 5 -trichlorophenoxyacetic acid ( 2 , 4 , 5 , - T ) , and 2 , 4 , 5 -trichlorophenoxypropionic acid ( 2 , 4 , 5 , - T P ) , which is also calledSilvex. Drums of organic material were stacked in an open fieldimmediately southwest of the production area, and untreatedprocess water was discharged from the western end of the plant toRocky Branch Creek.

Hercules Powder Company, now known as Hercules Inc.(Hercules), purchased the Reasor-Hill property and plant in 1961and continued to manufacture and formulate herbicides. The drumsthat were in the open area southwest of the central process areawere buried in what is now referred to as the Reasor-HillLandfill. From 1964 to 1968, Hercules produced the herbicideAgent Orange, a mixture of equal parts of 2 , 4 , 5 -trichlorophenoxyacetic acid ( 2 , 4 , 5 - T ) and 2 , 4 -dichlorophenoxyacetic acid ( 2 , 4 - D ) . Hercules discontinuedoperations at the site in 1971.

From 1971 to 1976, Hercules leased the plant site toTransvaal, Inc. (Transvaal), a predecessor company of Vertac Inc(Vertac). Transvaal resumed production of 2,4-D andintermittently produced 2 , 4 , 5 - T . Organic wastes from thesemanufacturing processes were stored and then buried by Herculeson the site in what is now referred to as the North Landfillarea. Transvaal purchased the property and plant from Herculesin 1976. In 1978, Transvaal underwent a Chapter XI bankruptcyreorganization and ownership of the site was transferred to thenew company, Vertac Chemical Corporation, which is the presentowner.

In 19 7 9 , ADPC&E issued an order that required Vertac toimprove its hazardous waste practices, and in 1980, EPA andADPC&E jointly filed suit in federal district court againstVertac and Hercules. A Consent Decree entered into by EPA,ADPC&E, Vertac, and Hercules in January 1982, required that anindependent consultant assess the conditions of on-site wastesand develop a proposed disposal method for the wastes. Theproposal, called the "Vertac Remedy", was deemed by EPA to beunsatisfactory. The court decided in favor of the proposed

4

__ a... ri^aii,^tDRAH so00remedy, which was implemented in the summer of 1984 and completed <^

in July 1986. As part of the remedy, the Vertac plant cooling ^water pond was closed, and sediment from this unit was removed Qand place in an above-ground vault. The Reasor-Hill and (_^Hercules/Transvaal Landfills were capped, and a french drain and , ,leachate collection system were installed around the burial , .(landfill) areas. Ground water monitoring wells were alsoinstalled, and a ground water monitoring program was initiated.

Vertac operated the plant until 1986. On January 31, 1987,Vertac abandoned the site and declaimed bankruptcy leavingapproximately 29,000 drums of 2,4-D and 2 , 4 , 5 - T wastes. Many ofthese drums were corroded and leaking. At that time EPAinitiated an Emergency Removal Action to stabilize and secure thesite.

In 1988, ADPC&E contracted for the incineration of thedrummed waste, using a $10.7 million combined trust fund anletter of credit obtained from Vertac during bankruptcylitigation. A contract for the incineration of the drummed wastewas signed in 1989 between ADPC&E and Vertac Site Contractors( V S C ) . VSC is a joint venture of MRK Incineration and Morrison-Knudsen Environmental Services. In January 19 9 2 , ADPC&E approvedthe VSC trial burn and production incineration began. Because ofthe difficulty in handling the Vertac drummed waste materialincineration operations took longer than originally anticipated.In May 199 3 , the trust fund money had been expended withapproximately 50 percent of the waste destroyed under the State'scontract. In June 1993, EPA took over the incineration operationand completed the incineration of the D-waste drums in September1994. EPA has now contracted for the off-site incineration ofthe remaining 3,100 drums of T-waste. Shipments of T-waste tothe APTUS commercial hazardous waste incineration facility,located in Coffeyville, Kansas, will occur over the next 12months.

Currently, there are no manufacturing operations at thesite. At the time operations were shut down, Vertac "mothballed"the plant. Mothballing involved flushing process lines anddraining several of the process vessels. Continuing activitiesat the site include operation of an on-site water treatment plantby Hercules under the terms of the 1986 consent decree. Thetreatment plant processes ground water collected in French drainsconstructed downgradient (south and west) of the old waste burialareas, and surface water runoff collected in a series of drainageditches and sumps that surround the central process area. Thistreated water was originally piped to the West WastewaterTreatment Plant owned and operated by the city of Jacksonvilleand was discharged into Bayou Meto. As part of ongoing remedialactivities at the site, Hercules, Inc. has recently completed thecleaning and regrouting of certain sections of the sewer linesthat run through the site to the West Wastewater Treatment Plant,

r- A^\L ' • • "-* and as such, water that was discharged to the sewer interceptor °0on the site is now treated and discharged directly into Rocky <0Branch Creek (after meeting discharge limits established by ^ADPC&E). <-?

The Vertac site was added to the National Priorities List(NPL) of hazardous waste sites in 1982. Once the site was placedon the NPL, money available from the Comprehensive EnvironmentalResponse, Compensation, and Liability Act of 1980, commonlycalled Superfund, could be used to investigate and study theproblems at the Vertac site and find ways to correct them toprotect the public health and the environment.2 . 2 ENFORCEMENT ACTIVITIES

A Potentially Responsible Party (PRP) search was notconducted since the Agency knew the identities of former owners,operators, and some generators of waste at the Vertac site, andsince litigation was already ongoing prior to CERCLA activities.However, CERCLA Section 104(e) information request letters weremailed in March 1990, and later to several companies which had"tolling agreements" with the Vertac Chemical Corporation and/orHercules Inc.

The following is a chronology of enforcement activity at theVertac site:1. Litigation was filed in 1980 under RCRA Section 7003 and

other statutes by the United States and the State ofArkansas against Vertac Chemical Corporation and HerculesInc. (the " P a r t i e s " ) . In January 1982, EPA and the State ofArkansas entered into a Consent Decree with Vertac ChemicalCorp. and Hercules Inc. in the litigation for developing aremedial plan for,certain on-site and off-site areas. AfterEPA invoked dispute resolution and had a hearing on theremedy, the court ordered the implementation of the "VertacRemedy" in July 1984 (see Site History for a discussion ofthe action taken).

2. In July 19 8 6 , pursuant to an agreement between the partiesand entry by the court, Vertac established an EnvironmentalTrust Fund, as part of a bankruptcy agreement. Vertacplaced $6 , 7 0 0 , 0 0 0 . i n this fund to be used to remediateportions of the plant. A $4,000,000 letter of credit waslater added to this Trust Fund also for the purpose offuture site remediation. Both EPA and the State of Arkansashad access to this fund which was later used to incineratethe 29,000 drums of waste left at the site by Vertac.

3 . In August 1986 , EPA issued a Unilateral Administrative Orderto all PRPs to require posting of warning signs and thefencing of portions of the West Waste Water Treatment Plan

r-- ,-\, \f a< t . ' p-J s• .•'•'•as. "

"" and certain areas of Rocky Branch Creek. This work wasperformed by Hercules.

0000<^<M

4. In January 1987, EPA issued a notice letter to Vertac , ^Chemical Corp. that required Vertac Chemical Corp. to , ,continue operation and maintenance of the leachate , ,collection and treatment system which was established aroundold on-site waste burial areas.

5. In June 1988, EPA signed an Administrative Order on Consentwith Hercules to allow Hercules to implement the fine gridsampling investigation for specific off-site areas.

6 . In September 1988, EPA signed an Administrative Order onConsent with Hercules that required Hercules to removeapproximately 3,000 cubic yards of dioxin contaminated soilfrom residential yards near the facility.

7. In July 1989, EPA,signed an Administrative Order on Consentwith Hercules that required Hercules to conduct the on-siteRemedial Investigation/Feasibility Study (RI/FS).

8. In March 1990, EPA sent CERCLA Section 104(e) informationrequest letters to several companies which had been involvedin business deals with the Vertac Chemical Corp. andHercules Inc . , including "tolling agreements".

9 . In July 1990, EPA-sent General Notice letters to the PRPsregarding the proposed off-site remedial plan and other siteactions.

10. In February 1991, the District Court entered a ConsentDecree between the United States and "Phoenix Parties",which are companies related to the Vertac Chemical Corp.,and which carried on the remaining business of Vertac undertheir names after Vertac abandoned the site. Herculesappealed the entry of the Consent Decree to the EighthCircuit Court of Appeals, which upheld the entry of theConsent Decree in April 1992. Under the terms of theConsent Decree, the Phoenix Parties have contributed$1,840,000 to a RCRA Closure Trust Fund, and will contributea percentage of pre-tax profits for 12 years, in return forrelease of liability.

11. Hercules Inc. had opposed the United States' efforts toselect a remedy for the off-site area at Vertac. Thisopposition included a motion filed in September 199 2 , toenforce the 1982 RCRA Consent Decree. The parties wereultimately unable to resolve their differences regardingthis motion. In June 1992, the trial court entered an orderdenying Hercules' motion to enforce the Consent Decree, andallowed EPA to CERCLA procedures to select remedies for the

7

^ r r i' 'J^ osVertac site. °0<^

12. The United States'added CERCLA Section 107 cost recovery <claims against Hercules, Dow Chemical Company, and Uniroyal Chemical Limited of Canada, in a complaint filed in March, (—*1992. By order of the trial court in June 1992, thiscomplaint was administratively closed, and the claimsasserted against Hercules, Dow, and Uniroyal wereconsolidated with the existing litigation. Other parties,including BASF AG, Standard Chlorine, and Velsicol, havebeen added to the litigation as third-party defendants.

13. Special notice letters for Remedial Design/Remedial Action(RD/RA) for the off-site areas were sent to the PRPs inAugust 1992. No "good faith" offers were received inresponse to the letter. A subsequent special notice letterwas sent in December 1992, to the PRPs after EPA revised thescope of the remedial work at the off-site areas.Negotiations regarding this work did not result in an RD/RAConsent Decree.

14. In June 19 9 3 , EPA signed an Administrative Order on Consentwith Hercules to allow Hercules to implement the RemedialDesign and Remedial Action for the Off-site ROD, which wassigned in September of 199 0 .

15. In March 1994, EPA signed an Administrative Order on Consentwith Hercules to allow Hercules to implement the RemedialDesign and Remedial Action for the Operable Unit 1 ROD,which was signed in June of 1 9 9 3 .

1 6 . The Liability phase of the on-going litigation was completedin October 1994, when the United States was granted a motionfor summary judgement against Hercules Inc. for joint andseveral liability. The claims made by the United Stateswere against Hercules, Inc., Dow Chemical Company, andUniroyal under CERCLA Section 107, for recovery of costsrelated to the Vertac site, including EPA removal costs.The claims against Dow and Uniroyal were based on tollingagreements that those companies had with Vertac, where theysent raw materials to Vertac for processing into finishedproduct that was shipped back to them. Prior to a liabilityphase trial, the United States settled its claims againstDow through a Consent Decree for $3.5 million. Settlementswere also reached with Velsicol and the United States onbehalf of the Department of Defense.The only United States claims remaining unresolved afterthese settlements were those against Uniroyal. Theliability phase of the trial against Uniroyal was concludedin November 19 9 3 . A jury, sitting both as an advisory juryand a fact-finding jury, returned a verdict finding Uniroyal

iu^ " also liable at the site for CERCLA §107 costs, but thattheir involvement was divisible. To date, the court has notentered its order addressing the findings of the jury, andthe cost phase of the trial has not been initiated.

17. Although not specifically enforcement related, severalseparate citizens suits were filed seeking to haltincineration of the 29,000 drums of dioxin contaminatedstill bottom wastes which were stored at the site. They areas follows:After the incineration contract was finalized, but beforethe first trial burn, came National Toxics Campaign (NTC) .e t.al. v. Arkansas Department of Pollution Control andEcology (ADPCE). et. al. seeking to enjoin the impendingtrial burn. After six days of testimony, the trial courtdenied a preliminary injunction based on the merits. NTCdismissed their lawsuit in federal court.Incineration opponents sued again, in chancery court, on themorning of the same trial burn approved in federal courtduring the NTC litigation. This suit. Ruby Brown and SharonGolgan v. ADPCE. was filed in Pulaski County Chancery Court.The chancellor denied the temporary restraining order on themerits after a hearing that day.After thousands of D-waste drums had been burned, ADPC&Edirector announced that T-waste would be burned after alimited burn of T-waste so that ambient air and incineratorstack data could be evaluated for risk considerations. Thisannouncement brought the lawsuit by the Arkansas PeaceCenter (APC) et. al. in October 1992. During thislitigation, control of the incineration passed from state toEPA control, after state funds were exhausted.The APC litigation resulted in a preliminary injunction (theMarch 17, 1 9 9 3 , order mentioned above), a stay of thatinjunction by the Eighth Circuit based on both jurisdictionand the merits, and eventually dismissal due to lack ofjurisdiction.After denial of petition for appeal to the U . S . SupremeCourt, plaintiffs filed suit again in chancery court inApril 1994. That case was removed to federal court andeventually dismissed. In the dismissal order, the districtcourt found that the lawsuit was barred by CERCLA 113(h)since the lawsuit was clearly designed to stop incineration.The district court also found that dismissal was appropriatebased on res judicata. i . e . , the same case had already beentried.

< . ; • yf< ; • - ^ S»:-.\^-^^.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION

A community relations plan for the Vertac site was put inplace in 1983. This plan list contacts and interested partieswithin the federal, state, and local governments, variousorganized affiliations, and local citizens. It also establishescommunication pathways to ensure timely dissemination ofpertinent information about site activities. Extensive communityoutreach has been performed in Jacksonville over the yearsthrough the release of information fact sheets, by conductingfrequent open houses and work shops, and through numerousmeetings with local civic groups and media representatives(newspapers, radio and T V ) . Reports updating activities at thesite are also distributed to the mayor, interested civic groups,and the local media on a weekly basis. A satellite communityrelations office was established in Jacksonville in July 1990 toprovide easy access to documents and information, and to providea local contact for questions and concerns.

In February 1995, EPA released the draft Feasibility Study(FS ) for Operable Unit 2 , and several meetings were held inJacksonville with local citizens groups and the press to discussthe various options being considered. The Operable Unit 2Feasibility Study was finalized in April 1 9 9 5 , and was madeavailable to the public at five local repositories (JacksonvilleCity Hall, Public Library, Police Courts Building, Air Force BaseLibrary, and ADPC&E). The official Administrative Record forthis Operable Unit is maintained at EPA in Dallas, theJacksonville City Hall, and the Arkansas Department of PollutionControl and Ecology in Little Rock.

On May 25, 1995 EPA held an informal open house inJacksonville to discuss EPAs proposed plan of action forcontaminated soils at the Vertac site. The meeting was wellattended by Jacksonville citizens, members of the citygovernment. State Health Department representatives, numerouslocal civic groups, and the technical advisor for the TAG grant.At that time, the proposed plan was released to the public forreview and comment. Several weeks prior to the informal openhouse the EPA project manager met with the local press to discussthe major elements of EPAs proposed plan which received coveragein both local papers and the State paper.

A Technical Assistance Grant (TAG) was awarded by EPA in1989 to a citizens group called Jacksonville People With PrideClean Up Coalition (JPWPCUC). This award was challenged bycitizens groups that competed for the grant, who alleged thatJPWPCUC was funded by the Potentially Responsible Parties (PRPs)for Vertac. Upon investigation by EPA, the grant was annulledafter it was determined that the JPWPCUC TAG application listedtheir source of matching funds as a bank account shared withtheir larger "parent" group, the Jacksonville People With Pride.

10

This parent group had indeed accepted monetary contributions from ^Vertac PRPs, and since these funds were not distinct from those ^of JPWPCUC, EPA determined that a possible conflict of interest -could exist, resulting in annulment of the TAG in December 1991. ^

TAG availability was again advertised in January 1992, andthe grant was awarded to the Concerned Citizens Coalition (CCC)in April 1993 after considerable effort by EPA to facilitateconsolidation of four competing citizen groups. CCC thensolicited several technical groups in order to select a technicaladvisor for the TAG. The Environmental Compliance Organization(ECO) was selected as the technical advisor and has been activein reviewing site documents for the community.

On June 15, 1995, EPA held a formal public meeting inJacksonville at the community civic center to discuss EPAsproposed cleanup scenario for dioxin contaminated soils at theVertac site. At that meeting EPA attempted to address allcomments or questions raised concerning the proposed cleanup andformally accepted all public comments. Over 100 citizensattended the meeting, including members from the JacksonvilleChamber of Commerce, Jacksonville City Council, the Mayor,representatives from ADPC&E, and the State Health Department.The comment period for the proposal ran from May 26 throughAugust 11, 1 9 9 5 , after two extensions. All comments received byEPA prior to the end of the public comment period, includingthose expressed verbally at the public meeting, are addressed inthe Responsiveness Summary section of this Record of Decision.Thus, the requirements of CERCLA Sections 1 1 3 ( k ) ( 2 ) ( B ) ( i - v ) and117, 42 U . S . C . § § 9 6 1 3 ( k ) ( 2 ) ( B ) ( i - v ) and 9617, were met during theremedy selection process.4 . 0 SCOPE AND ROLE OF OPERABLE UNIT

The problems at the Vertac Superfund site are complex andthe EPA has determined that site remediation can be accomplishedmost efficiently in six phases. This ROD addresses one of thesix cleanup phases i . e . . Operable Unit 2 , which consists of; on-site soils, off-site soils and sediments, underground storagetanks, underground utility lines, building and equipmentfoundations, curbs, and pads.

The studies undertaken at the Vertac Superfund site forOperable Unit 2 media have identified that the soils at the siteto be a low-level threat in light of all the media beingremediated at the site. Generally, EPA associates principlethreats with liquids, areas contaminated with high concentrationsof toxic compounds, and highly mobile materials that generallycannot be reliably contained. Low-level threat wastes are thosesource materials that can be reliably contained and that wouldpose only a low risk in the event of a release. Wastes thatgenerally are considered to constitute a low-level threat

11

(> •

COinclude; surface soils containing contaminants of concern that ^are relatively immobile in air or ground water i . e . , non-liquid, ^low volatility, and low leachability (see Guidance to principal Qthreat and low-level threat wastes, Nov. 1991, EPA Pub. No. Q9 3 8 0 . 3 - 0 6 F S ) . ^

4

The concentrations of dioxin present in Vertac soils are igenerally an order of magnitude lower than the concentrationsfound in the dioxin containing liquids (both drummed still bottomwastes and process tank sludges), and as such, are identified asa low-level threat based on relative concentration to other sitemedia. The dioxin in the Vertac soils also fit the definition ofa low-level threat due to the fact that they are relativelyimmobile except through sediment transport, i . e . , soil migrationfrom rainwater runoff. Dioxins are characterized as having avery low solubility in water and a very low vapor pressure (theydon't readily leach to ground water or vaporize to the a i r ) . Inaddition, numerous studies have also shown that dioxin bindstightly to fined grained and organic rich soils further reducingits mobility.

Dioxin, however, is considered to be a highly toxiccompound, and if left unremediated would continue to present aserious threat to the public health and the environment due tothe potential for cancer and noncancer effects, and would alsocontinue to present potential long term threats to theenvironment from the migration of contaminants off-site throughvarious sediment transport mechanisms.

Remedial action objectives have been developed to addressthe compounds of concern at this site, namely, TCDD and otherdioxin and furan congeners, chlorobenzene,chlorophenoxyherbicides, chlorophenols, and toluene. Theremedial action objectives are formulated in such a way thatresidual contaminant concentrations in the media of concern arereduced or controlled to a level where exposure of anenvironmental receptor.to the contaminants does not result in anunacceptable carcinogenic risk or an adverse toxic response whenconsidering the intended future use of the site.

The remedial action objectives which are applicable to theOU2 media are as follows:• Prevent exposure of future site workers to concentrations of

site contaminants in surface soils that remain followingremedial activities which would result in an excess lifetimecancer risk greater than 1 in 10,000 to 1 in a 1,000,000.

• Prevent exposure of future site workers to concentrations ofsite contaminants that would result in an adverse toxicresponse.

12

^^fibfl, ; .&< — ^«"' • Prevent off-site residents at the fence line from exposure ^

to site contaminants at concentrations resulting in an ^excess lifetime cancer risk of 1 in 10,000 to 1 in a ^1,000,000. , 0

<—>• Prevent off-site environmental receptors from exposure to . •site contaminants that would result in an adverse toxicresponse.

• Prevent/control dust generation during remedial activitiesand/or removal activities to the maximum extent practicable.

• In concert with OU3 (ground water) remedial activities,prevent potential contamination of the on-site and off-siteground water by releases from below ground portions of theplant, and

• Destroy and/or contain hazardous substances generated by theremedial ion.Following is a description of the six cleanup phases or

operable units that are currently in progress, or have beencompleted at the Vertac site. Collectively, the completion ofall six phases is intended to address all environmental risksposed by the site.Phase 1 The "VERTAC REMEDY"

ADPC&E issued an order in 1979 that required Vertac, Inc. toimprove their hazardous waste practices, and in 1980 EPA andADPC&E jointly filed suit in federal district court againstVertac, Inc. and Hercules, Inc. A Consent Decree entered into byEPA, ADPC&E, Vertac, and Hercules in January 1982 required anindependent consultant to assess the conditions of on-site wastesand to develop a proposed disposal method for the wastes. Theproposal, called the "Vertac Remedy," was deemed by EPA to beunsatisfactory and EPA returned to court in early 1984 for aresolution. The court decided in favor of the proposed remedy,which was implemented in the summer of 1984 and completed in July198 6 .

As part of the remedy, the Vertac plant cooling water pondand the equalization basin were closed and sediments from theseunits were removed and placed into an excavated area whereearlier operators had buried drums of waste. The burial area wascapped and a French drain and leachate collection system wereinstalled around the burial areas. Ground water monitoring wellswere also installed and a ground water monitoring program wasinitiated.

13

Ifii 2 DRUMMED WASTE INCINERATION (J^<£>In 1989, ADPC&E signed a contract to have approximately ^

29,000 barrels of 2,4-D and 2 , 4 , 5 - T herbicide still bottom wastes oincinerated on-site. Wastes from the production of 2 , 4 , 5 - T at c.^this site have been found to contain up to 50 ppm of dioxin, .while wastes from the production of 2,4-D generally containdioxin in the low parts per billion range. All drummed wastesare treated as F-listed (dioxin containing) wastes.

The State used funds from the trust fund that wasestablished when Vertac went bankrupt. Incineration of thesewastes began in Fall 1990. In June of 1993, funding for theproject was depleted and EPA assumed immediate responsibility forincinerating the remaining drums as a time critical removalaction. In late September 1994, the incineration of 25,179 drumsof dioxin contaminated 2,4-D waste was completed at the Vertacsite. In July of this past year EPA announced that it wouldpursue the off-site incineration of approximately 3,200 drums ofdioxin containing 2 , 4 , 5 - T waste located at the Vertac site. OnNovember 9 , 1994, a contract was signed between the APTUScommercial incineration facility in Coffeyville, Kansas, andEPA's prime contractor URS Consultants, to accept the Vertacdrummed T-waste material. The first shipment of T-waste went toAPTUS in November 1994, with the remainder of the drums beingshipped over the next 12 months.Phase 3 VERTAC OFF-SITE AREAS

A Record of Decision was signed in September 1990 to addressthe cleanup of off-site areas that were contaminated as a resultof untreated and partially treated surface and undergrounddischarges of plant wastewater, and other releases. Elements ofthis operable unit include; an active sewer interceptor and anabandoned sewer interceptor, portions of an abandoned tricklingfilter sewage treatment plant (Old STP), an active westwastewater treatment plant (WWTP), and the sediments along theRocky Branch Creek flood plain. The selected remedy calls forremoving sediments from the active sewer interceptor, installingpipe liners in the clean sewer, filling the abandoned interceptorwith grout, and removing sludge from the sludge digester in theold STP. Sludge drying beds in the old STP will be capped withone foot of clean soil and the aeration basin in the WWTP will bedrained and demolished. Flood plain soils along Rocky BranchCreek that are contaminated with dioxin in excess of one part perbillion ( p p b ) , will be excavated for treatment at Vertac.Monitoring of fish in Rocky Branch Creek and Bayou Meto fordioxin will continue.

Hercules has completed the remedial design and has startedthe remedial action under the terms of an UnilateralAdministrative Order issued in July 1993. The Order required

14

n^ M' i. • ^LJt'''^ CT>Herdtfles to conduct the remedial design and remedial action to ^implement the selected remedy, except the on-site incineration of soils excavated from the Rocky Branch Creek flood plain was ^deferred to make the disposal of excavated off-site soils r^consistent with the disposal of on-site soils. Off-site remedialaction (except for the excavated flood plain soils) was completedin November 1995.Phase 4 ON-SITE ABOVE GROUND MEDIA

A Record of Decision for the above ground media was signedin June 1993. The above ground media includes buildings, processequipment, left over chemicals in the process vessels, spentactivated carbon, shredded trash and pallets, and miscellaneousdrummed wastes at the site. The selected remedy consists of: ( 1 )on-site incineration of F-listed process vessel contents, spentcarbon, shredded trash and pallets, and miscellaneous drummedwastes; ( 2 ) off-site incineration of PCB transformer oils andnon- F-listed process vessel contents; ( 3 ) recycle/reuse ofdecontaminated process equipment to the maximum extentpracticable; ( 4 ) on-site consolidation of debris resulting fromdemolition of buildings and equipment that cannot berecycled/reused in a RCRA subtitle C landfill; and ( 5 ) disposalof treatment residues consistent with disposal of ash and saltcurrently being generated by the incineration of drummed wastesat the site.

An Unilateral Administrative Order was issued to Hercules inMarch 1994 to perform the remedial design and remedial action.Remedial design work plan has been approved. Hercules hasexpressed interest in pursuing off-site incineration and hassigned a contract with APTUS, an off-site commercial hazardouswaste incineration facility. An Explanation of SignificantDifference (ESD) has been issued by EPA to allow off-siteincineration.Phase 5 SOILS AND UNDERGROUND UTILITIES (Operable Unit 2)

Operable Unit 2 media are the subject of this ROD, andincludes surface and subsurface soils, underground utilities,underground fuel storage tanks, foundations, curbs and pads.Other soil and sediment media that will be covered in this RemedyDecision include; off-site soils from the Rocky Branch Creekflood plain, sludge and sediment from Old Sewage Treatment Plantsludge digester, and bagged soils excavated from residentialyards in 1990.

EPA made a decision in two previous Vertac RODS to addressthe treatment of the off-site soils from the Rocky Branch Creekflood plain, sludges from the Old Sewage Treatment Plantdigester, and bagged soils excavated from residential yards, inthis ROD, so that similar waste materials (particularly soils and

15

!>sediments) associated with the Vertac site would be treated in a °^consistent manner. '-

The ROD for the off-site area, September 1990, called forthe excavation and incineration of soils in the flood plain areaalong Rocky Branch Creek that had a 2,3,7,8-TCDD concentrationgreater than 1 ppb. The estimated volume of flood plain soils isapproximately 4,100 cubic yards. The off-site ROD also calledfor the incineration of sediments removed from the digester atthe Old Sewage Treatment Plant. The approximate volume ofsludges from the digester is 800 cubic yards. The ROD for OU1,deferred the treatment decision for the bagged soils removed fromresidential yards as a part of a removal action in 1990. Thetotal volume of bagged soil is estimated at 2,770 cubic yards.Phase 6 GROUND WATER

Hercules completed the Remedial Investigation/FeasibilityStudy (RI/FS) for this phase of the site cleanup in September1995. Remedy selection is expected to occur in early 1 9 9 6 .

Ground water remediation at the Vertac site will posecertain technical challenges due the combination of complexsubsurface geology (tilted, fractured bedrock), and the presenceof dense nonaqueous phase liquids (DNAPLs). Ground water isgenerally contaminated with chlorophenols,chlorophenoxyherbicides, and dioxin.5 . 0 SUMMARY OF SITE CHARACTERISTICS

5.1 DEMOGRAPHY AND LAND USE IN THE AREA OF THE SITE

The Vertac site covers approximately 192 acres on MarshallRoad within the city limits of Jacksonville, Arkansas, population2 9 , 0 0 0 . Approximately 1,000 residents live within one mile ofthe site with residential areas bordering the entire east andsouth sides. The west and northern sides of the site are boundedby an industrial area and the Little Rock Air Force Base.

The Vertac site is currently zoned for industrial use andhas been used for commercial/industrial operations forapproximately 50 years. Land use zoning near the Vertac plant isshown in Figure 3 . The area just south of the Vertac site,between Marshall Road and the Missouri-Pacific railroad tracks,south to West Main Street, is a residential area made up of bothsingle family homes, and apartments. The area immediately westof the railroad tracts and north of West Main Street has recentlybeen developed and supports several light industries. The areabetween West Main Street and South Redmond Road is commercial andlight industrial. Just south of South Redmond Road isundeveloped land that includes the Jacksonville Sewage TreatmentPlant, DuPree Park, and Lake DuPree. On to the south, the rest

16

0<—>

Land Use Zoning MapFIGURE 3

of the area consists predominantly of irrigated rice fields and ^woodlands. ^

<05 . 2 SOILS AND GEOLOGY <^05 . 2 . 1 Soils (_>

Soils in the area of the plant are classified as the i •Leadvale-Urban land complex with a 1 to 3 percent slope. TheLeadvale series soils is composed of moderately well-drainedsoils in valleys, formed mainly loamy sediment and washed fromuplands consisting of weathered shale, siltstone and sandstone,such as those that underlie the site. Leadvale soils aregenerally described as having moderately low permeability and aseasonally perched water table. The Leadvale-Urban land complexconsists of areas of Leadvale soils that have been modified byurban development. Because of the extensive development andearth-moving activities at the site, natural soil characteristicshave been obscured.5 . 2 . 2 Geology

The site lies in the transition zone between the CoastalPlain and the Interior Highlands Physiographic Provinces. Thesurficial geology of the Coastal Plain Province in the regionsurrounding the site is dominated by westward thinning wedge ofunconsolidated sediment consisting of the Tertiary Age ClairborneGroup, Wilcox Group, and Midway Formation.

The Clairborne Group and the Wilcox Group areundifferentiated along the fall line that occurs in the sitearea. The wedge onlaps the Rocks of Pennsylvanian Age lowerAtoka Formation, which dominates the geology of the InteriorHighlands Province in the region surrounding the site.Quaternary alluvium and terrace deposits occur locally alongdrainages in both provinces and are more common in the CoastalPlain Province. A generalized summary of the geologic formationssurrounding the site is presented in Table 1. A map of the sitegeology is presented in Figure 4.

The contact between the Tertiary Age sediments and thePennsylvanian Age rocks occurs along a regional trend northeastto southwest and is present in the area of the site. On a localscale, the trend of the contact depends on the current erosionalsurface and the paleotopographic surface of the Atoka Formation.The strike of the Wilcox Group Sediments and the Midway Formationtends toward the northeast-southwest. The dip of the sedimentsis low and oriented toward the southeast. The Midway Formationwas deposited, onto the irregular and weathered surface of theAtoka Formation, which was folded and fractured during the latestages of the Alleghenian orogeny. The Atoka Formation was lateruplifted and weathered. In the area of the site, the strike of

18

ERA

u0sgu

u

is

1£

SYSTEM

^

1

0

^

I"

^ -

1EU

-I

J BJ —

SERIES

HOLOCENE

PLEISTOCENE

EOCENE

PALEOCENE

UPPERCRETACEOUS

ATOKA

—^ - - — — «• —^«.q-^f« ^r«^%i ^k^si^« r^nkfl Af^%klA «km t»&vf« wri r»&i rrnm Daor rnn«i ilfanK 1 QOf

SUBDIVISION

ALLUVIUM

ALLUVIUMAND

TERRACEDEPOSITS

CLAIBORNEGROUP

WILCOXGROUP

MIDWAYFORMATION

UNDIFFERENTIATED

ATOKAFORMATION

Q

12 i i

'!u- d^<Q a:2cs3 <

t2

feS

THICKNESS(FEET)

0-50

0-156

0-700

0-800

0-500

0-500

500-1500

&<

3

UTHOLOGY

RED TO GRAY CLAY;OCCASIONALLY SILTY TO SANDY

*

BASAL SAND AND GRAVELOVERLAIN BY FINE SAND.

SILT AND CLAY

WHITE TO UGHTGRAY, FINE TOMEDIUM SAND;

GRAY TO TAN CLAYAND SANDY CLAY

SPECKLED UGHTGRAY AND BLACKTO BROWN CLAY;

UGNITIC CLAY ANDUGNITIC FINE SAND

DARK BLUE-GRAY TO BIACKNONCALCAREOUS TO VERY CALCAREOUSClAY; OCCASIONAL THIN BEDS OF WHITE

CLAY AND DENSE. FINE GRAINED SANDSTONE

UGHT GRAY TO WHITE, CALCAREOUS,FOSSIUFEROUS, GLAUCONITIC SANDSTONE;OVERLAIN AND UNDERLAIN BY SANDY CLAY

SHALE AND MARL

INTERBEDDED SHALE ANDSANDSTONE; SANDSTONE TIGHTLY

CEMENTED

YELLOWISH TOREDDISH-BROWNMOTTLED/CLAYEYSAND AND SANDY

CLAY; MOTTLEDGRAY UNDER

REDUCINGCONDITIONS

WATER SUPPLY

GENERALLY NON-WATERBEARING; DOMESTICSUPPUES AVAILABLEFROM BASAL UNITS

BASAL SANDS ANDGRAVELS YIELD UP TO

2000 GPM; MOSTIMPORTANT AQUIFER

IN AREA

NOTWELL

DEVELOPED

NOTWELL

DEVELOPED

GENERALLYNON-WATER

BEARING

DEEPLY BURIED;SAUNE WATER

WATER BEARING INOUTCROP ONLY;

DOMESTIC SUPPUESUP TO 10 GPM

CLEANSANDBEDSYIELD

DOMESTICSUPPUES

SUMMARY OF SELECTED GEOLOGIC FORMATIONS AND WATER - YIELDING ^^'^S-^CHARACTERISTICS FOR REGION SURROUNDING VERTAC SITE p^uch(?%o) ' '

002700

Q:

M327-4127

QuJtemwyAlluvium - Red to Gray Clay.Occasionally Silly to Sandy

Terrace Deposits - Basal Sand andGravel Overlain by Fine Sand.Silt and Clay

TertiaryWllcox Group - Orange<ed toRed-brown Silly Sand to Silly Clay

l—fl Midway Formation - Light Gray Clay11"'111 or Silly Clay.

PennsylvanlanAtoka Formation - Interbedded;Sandstones. Siltstones and Shales

SUke • Slip Fault Indicating RelativeMotion

^ Normal Fault Indicating Dip Direction

Sources: C. Stone. Cabot Geologic QuadrangleMap. 1968

C. Stone, CUmstead GeologicQuadrangle Map. 1968

B. Haley and C Stone. JacksonvillleGeologic Quadrangle Map. 1968

C. Stone and B. Haley. McAlmontGeologic Quadrangle Map, 1968

400 ____ 800 1200

Sate In F—t

GEOLOGIC MAP OF THEJACKSONVILLE, ARKANSAS AREA

•^ •"<"fc. V\i \ v, "'.<^ IX>5V^»?• - <-Stthe beds in the Atoka Formation trends N70°W and dip of about —35°NE. The Atoka Formation outcrops along Rocky Branch Creek on 0

I>the western side of the property. - '(••<5 . 3 HYDROLOGY °

5 . 3 . 1 Surface Water ,Because of the potential for surface runoff to transport

potentially contaminated soils off of the site, previous remedialactions included the installation of sumps for the collection andtreatment of the first flush of surface water runoff from thecentral process area. After treatment, this water is dischargedto Rocky Branch Creek. Runoff that exceeds the capacity of thesumps flows to the Rocky Branch Creek. This ROD will in partaddress potentially contaminated sediments that bypass the sumpsafter they are inundated by heavy rains.

There are two major drainageways in the area. Rocky BranchCreek, and Bayou Meto which is a tributary to the Arkansas River.The Rocky Branch Creek flows through the part of the site west ofthe central process area. Approximately 2 miles downstream,Rocky Branch Creek flows into Bayou Meto.

Surface drainage ditches on the western part of the sitedirect local runoff westward toward Rocky Branch Creek. Anearthen dam was constructed across the creek in the early 1950'sto form a cooling water pond that was used to supply non-contactcooling water to the plant.

At its maximum extent, the pond extended to a distance ofabout 1,000 feet north of the dam. The pond was adjacent to thenorth burial area. The dam was removed and the cooling waterpond was closed in July 1985. Rocky Branch Creek was divertedaround the location of.the former cooling water pond as a part ofthe pond closure. The diversion is maintained today by anearthen dike along the eastern side of the creek.

Surface water runoff from the western part of the centralprocess area (including the central ditch that transects thecentral process area) is contained in drainage ditches thatdivert the runoff to sumps. The sumps are connected to the watertreatment plant, which uses activated granular carbon to treatthe water.

Surface drainage ditches in the northeastern part of thesite direct runoff eastward toward a primary ditch that liesalong the western side of Marshall Road. This ditch directswater toward Rocky Branch Creek south of the site.

21

, ^ . - . - )^ w. • • • • '1?:.^°"»CO5 . 3 . 2 Ground Water Q2>This ROD does not address the ground water issue at the c<i

Vertac site. The Operable Unit 3 ROD, scheduled for early 1 9 9 6 , owill address ground water contamination. <^,

Ground water in the region surrounding the site occurs in 'both the overburden and the underlying bedrock. The overburdenand bedrock are generally not considered as major sources ofground water near the site. Ground water supplies in the regionare obtained from the unconsolidated sands and gravels in theTertiary and younger Quaternary sediments. Most ground water isproduced from wells completed in the sands within the WilcoxGroup and basal sands and gravels within the Pleistocene alluviumand terrace deposits. Yields from these deposits can range up to2,000 gallons per minute ( g p m ) . Ground water in theunconsolidated sediments is present in the primary intergranularpore space. Some domestic ground water supplies are obtainedfrom the Atoka Formation. Yields can range up to 10 gpm. Groundwater in the bedrock is present in fractures and partings withinthe rock.

The hydrology in the area of the site is influenced by thelocation of Rocky Branch Creek, the french drain, the centralditch, and the hydraulic characteristics of the overburden,weathered rock, and bedrock.5 . 4 REMEDIAL INVESTIGATION FINDINGS

5 . 4 . 1 BackgroundSite investigations and remedial actions have been performed

at the site since 1978. Figure 5 shows an overview of theremedial action performed at the site to date, mostly involvingthe closing of a cooling water pond, capping old landfills andburial areas, and the installation of a french drain leachatecollection around the landfills.

Hercules Inc. completed the RI for OU2 Phase 1 in December19 9 2 , which addressed surface and subsurface soils, shallowground water, and underground structures such as; undergroundutilities, foundations, curbs, pads and fuel storage tanks. TheOU2 Phase 2 RI, completed in September 1995, principallyaddressed deep ground water contamination and some additionalsoil investigation in the northern part of the site. Groundwater has since been split off into a separate operable unit(OU3) for the purpose of expediting the completion of the soilsand underground structures remediation effort, and is not a partof this ROD.

The RI for OU2 has shown that nature and levels ofcontaminants found in the soils at the site tend to parallel

22

Capped Equalization Basin AreaSediment Containment VaultCapped Reasor-HNI Landfill AreaCapped North LandtHI AreaClosed Cooling Pond <^aExcavated Surface Solli AreaAsphalt-Capped Blow Out AreaScraped AreasFrench DrainSlurry WallFence UneCentral DitchRailroadDiversion DikeClay Barrier WanDrainage Ditch. •GunnHe-Covered

Surface Water SumpBuildings and Foundations

400 800ScarinF—t

Source- v«nKS«*BouniMryndPnotogr«n>netrlcSuvey Prepand by Wtt •nd AisoclMd. Inc

PrqjtCUon: Munus Coordinate SytMn.Nonh Zone (MAO 1«B3|.

AREAS OF PREVIOUS REMEDIATIONVERTAC SITE

JACKSONVILLE, AR

f02704

»f5particular process areas of the plant. The central process area Qof the site has been divided into 10 subareas based on j^.operational activities (see Figure 6 ) , they include: QQ

0• Maintenance Area - used for equipment repairs and storage of ^equipment, parts, and some raw materials. ,

t• Formulations Area - used for the storage of raw and finished

products (large warehouse and some process vessels).• Former Chlorination Plant Area - used in manufacturing 2,4-D

herbicide.• Existing Chlorination Plant Area - built in early 1980s and

replaced old Chlorination plant.• Esterification Plant - used to add alcohols to increase

solubility of the herbicide to water.• Dalapon Production Area - used in manufacturing dalapon

(1,1,1-fcrichloropropionic acid).• Recycle Liquor Storage Area - used for the storage of

manufacturing materials such as recycle liquor, causticsoda, and spent solvents. Currently used to store drumsgenerated by ongoing site activities.

• Recovery Plant - used in the treatment of process wastes.2,4-D waste were recovered, and drums containing 2,4-D werewashed.

• 2 . 4 , 5 - T Production Area - used in manufacturing of 2 , 4 , 5 - Therbicide.

• Acid Plant - chlorophenols were reacted with acetic acid andmonochloroacetic acid to form phenoxyacetic acid herbicides.The area around the Regina Paint Building, located in Parcel

1 (north area of the site) is included in OU2 because thebuilding was used to store empty drums that had been used handleor store wastes from the manufacture of 2 , 4 , 5 - T .The media addressed in the OU2 RI include:

Surface soilsSubsurface soilsTetrachlorobenzene (TCB) spill areaUnderground utilitiesUnderground Storage Tanks (USTs)Building Foundations and Curbed Areas

24

C02706

DRAFTOther media that will also be addressed in this ROD include; I'""

0• Off-site soils from Rocky Branch Creek flood plain t*"

(ROD September 1 9 9 0 ) . °10• Sludge from Old Sewage Treatment Plant sludge digester <-"

(ROD September 1 9 9 0 ) . '• Bagged soils excavated from residential yards

(ROD June 1 9 9 3 ) .Remediation of the off-site soils, sludges from the off-site

sewage digester, and bagged soils from a residential removalaction were originally addressed by EPA as response elements inprevious RODS. However, because of the similarities of thesemedia, and the wish to treat similar media in a consistent mannerEPA now will address these media with the on-site soil media.

The ROD for the off-site area, September 1990, called forthe excavation and incineration of soils in the flood plain areaalong Rocky Branch Creek that had a 2,3,7,8-TCDD concentrationgreater than 1 ppb. The estimated volume of flood plain soils isapproximately 4,100 cubic yards. The off-site ROD also calledfor the incineration of sediments removed from the digester atthe Old Sewage Treatment Plant. The approximate volume ofsludges from the digester is 800 cubic yards. The ROD for OUl,deferred the treatment decision for the bagged soils removed fromresidential yards as a part of a removal action in 1990. Thetotal volume of bagged soil is estimated at 2,770 cubic yards.5 . 4 . 2 Sampling Results for Surface Soils

During the period between 1989 and 1992 approximately 461grids were established,for the purpose of determining the levelof contaminants present across the site. EPA, IT Corporation,Hercules, Vertac Site Contractors, and Weston (contractor forHercules) were principally responsible for the collection of thisinformation (see Figures 1 , 8, and 9 ; early grid sampling,surface grid locations in the central process plant area, andsurface soils sampling outside the central process plant area,respectively).

Over 180 grids were sampled under the OU2 Phase 1 RI. Themajority of the grids were located in the central process areaand were approximately 5,000 square feet. These grids weresampled for 2-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol,2,6-dichlorophenol, 2,3,6-trichlorophenol, 2,4,5-trichlorophenol,2 , 4 - D , silvex, 2 , 4 , 5 - T , and 2 , 3 , 7 , 8 - T C D D . Grids outside thecentral process area are approximately 40,000 square feet, andwere screened for 2,3,7,8-TCDD only, because these areas wereoutside of known production operations. Eleven samples werecollected from a series of 11 uniform nodes within each grid.

26

000i>(M0<—

050I>(M0t—

<

——— Oulane of GridlOuulde DM Cenm Process Aref <

m WESTON Surface Sd Swiping Grid andNurrtw.Numtwi tor WBTON Gricb andGrab Sarr(ik3 Range from 400 Through US

0 WESTONSu«K«Sol(inbteiwlnguXJllonandNuntxr

•"* \*WONSurt»ce Sot Samptng Location WiMnttw Blow Out Alw

—-—• CennlProceii eiBoundwy

—— Proptny Boundary

400 800

Source V«uc SJU •oundaly and PhocogramfnetricSurv«y Prepared by W<H and AnodJtel. me

•LINQ ORID8OUTMOE THE CENTRAL PROCESS AREA

VERTACSITEJACKSONVILLE, AR

C02710

B 'a' ^-il I

From those 11 samples three composites were made andanalyzed for 2, 3 , 7 , 8 - T C D D . Essentially all areas exhibitingelevated TCDD concentrations are located in the central processarea, and relative concentrations of chlorophenoxyherbicides andchlorophenols measured in the surface soils paralleled dioxinconcentrations.

Most of the unsampled areas of the site were generally in adownstream direction from sampled areas exhibiting TCDDconcentrations of 2 ppb or less.

Table 2 depicts the maximum and average concentrations forthe contaminants of concern (COCs) at the site.Table 2 .

CHLOROPHENOLS2 -chlorophenol4 -chlorophenol2,4-dichlorophenol2,6-dichlorophenol2,3,6-trichlorophenol2,4,5-trichlorophenol2,4,6-trichlorophenol

CHLOROBENZENESTrichlorobenzene

CHLOROPHENOXYACIDS2 , 4 - D

Silvex2 , 4 , 5 - T

MftXIMDM CONC.3 ppm

0.12 ppm360 ppm15 ppm

0.73 ppm270 ppm79 ppm

17,000 ppm

5,500 ppm290 ppm710 ppm

AVERAGE CONC.1.9 ppm

not computed6.9 ppm

0.54 ppm0.54 ppm2.0 ppm3.5 ppm

not computed

191 ppm12.4 ppm23.1 ppm

TCDD concentrations at the site ranged between non-detect to2,200 ppb. The highest concentrations of TCDD found in surfacesoils at the site were in the following areas (note; TCDDconcentrations are reported as the 95 percent upper confidencelimit for each grid sampled in an area);• Blow Out Area - For the seven grids sampled in this area

TCDD concentrations ranged between 0.25 ppb for the leastcontaminated grid to 660 ppb for the most contaminated grid.The dioxin in this area is associated with occasionalreleases "blow outs" from the reactor vessel when the

30

control of the chemical reactions were not maintained.After such a release the solidified 2,4-D and 2 , 4 , 5 - T was c'1scraped from the ground and replaced with a thin layer of THclean fill material, r—

(M• East Drum Storage Field Area - TCDD concentrations for this 0

area ranged between 7. 3 ppb and 120 ppb. J

The east drum storage field can be subdivided into twodistinct areas. The first area includes the drainage gridsalong the northern side of the site entrance road. Dioxinin this area was most likely transported there from the blowout area. The second area is located in the western part ofthe drum field. Soil contaminants are most likely relatedto spillage from the drum storage operations.

• Main Boiler House Area - TCDD concentrations in this arearanged between 0 . 3 9 ppb and 1,270 ppb.This area acted as a sediment retention basin, and since itis located down downslope from the blow out area, TCDD islikely present from sediment migration from the blow outarea.

• Area East of the Main Boiler House - TCDD concentrations inthis area ranged between non-detect and 98 ppb.This area is down slope from the main boiler house,therefore, the TCDD may have originated at the blow out areaand migrated with sediments from the main boiler house area.

• Area of the Existing and Former Chlorination Plants - TCDDconcentrations in this area ranged between 22 ppb and2,800 ppb.Portions of this area was used to dry 2 , 4 , 5 - T , and TCDD issuspected to be present as the result of these dryingpractices.

• Maintenance Area - TCDD concentrations in this area rangedbetween 4 . 8 ppb and 57 ppb.Previous overpacking of leaking drums in this area may havecontributed to the TCDD found in this area.

5 . 4 . 3 Subsurface SoilsDuring the RI numerous subsurface soil samples were taken

from soil borings throughout the site. The purpose was todetermine whether significant sources of contamination existedbelow the surface soils which could potentially migrate anddegrade water quality. Analyses were performed on these samples

31

to quantify the concentrations of chlorophenols, (Y-)chlorophenoxyherbicides, and TCDD in these soils. ^

i>Of more than 90 samples taken and analyzed for TCDD, only 5 <were greater than 20 ppb. The range of the 5 samples were obetween 20 ppb and 310 ppb. These elevated levels were all c^,obtained in different borings and at different depths. •

iThe vertical extent of TCDD at depths greater than 36 inches

appears to be related to areas where burial occurred, such as thechlorination area, or where sediments may have accumulated suchas the main boiler house area. The vertical extent of TCDDbetween 12 and 36 inches is limited to areas where the landsurface may have been built up during subsequent site activities,such as the blow out area, and south of the chlorination area.The data suggest that TCDD contamination between 12 and 36 inchesof soil depth is not the result of downward migration of TCDDfrom the surface.5 . 4 . 4 Tetrachlorobenzene Spill Area

The tetrachlorobenzene (TCB) spill area resulted from anaccidental release of TCB from a railroad car. Molten TCB filledthe low area between the railroad tracks and penetrated into thesoils pore spaces under the tracks before crystallizing. Thespill area is about 830 square yards, based on where TCB wasobserved. The western limit was not found because access forexcavation was impeded due physical obstructions at the site,e . g . , building foundations, etc. The vertical extent was alsonot determined at the time of the RI for similar reasons. Thehorizontal and vertical extent of the TCB contamination will bedetermined during the remediation process. TCB was found atconcentrations ranging between 200 ppm and 1,700 ppm in pitsamples at depths of 32 to 34 inches below ground surface.5 . 4 . 5 Underground Utilities

Because TCDD tends to adsorb to clay-rich and organic richsoils and the potential for the compound to migrate with thesesediments if they are transported by water flow, samples weretaken from several underground utility lines including theindustrial and sanitary sewer lines, as well as, surface watersumps. Pressurized piping (natural gas lines and public waterlines) were not sampled since there was no accessible point ofentry to these lines at the site due to the fact that they wereunder constant pressure.Five samples were collected for each structure.• Industrial Sewer - sediment samples showed the highest TCDD

concentrations of any underground utilities, with theconcentrations ranging between 7. 3 ppb and 79 ppb.

32

SJ'^^r i• Surface Water Sumps - sediment samples for TCDD from the

surface water sumps ranged between 8.4 ppb and 18 ppb, andare generally consistent with the soil concentrations withinthe central process area.

• Sanitary Sewer - the lowest concentrations of TCDD found inthe underground utilities was found in the sanitary sewersystem, and ranged between non-detect to 4. 1 ppb.Measurable concentrations of TCDD were found in the on-sitesewer lines extending southeastward from the central processarea. No TCDD was found in the currently active portions ofthe sanitary sewer which extends southward of the site.

• Porous Bedding Material around Underground Utilities - thereare no field information or design drawings available whichindicates whether or not granular material was used forbedding of these lines, thus the potential for preferentialflow of ground water in bedding material around the outsideof utility piping may exist at the site.

5 . 4 . 6 Underground Storage TanksA survey of the underground storage tanks (USTs) for the

site indicated the presence of 5 tanks, with capacities rangingbetween 250 gallons and 1,000 gallons. All 5 tanks havepreviously been used to store gasoline or diesel fuel. Theapproximate volume of residual fuel in the tanks is as follows:

UST1 - 42 gallonsUST2 - 57 gallonsUST3 - 17 gallonsUST4 - 35 gallonsUST5 - 208 gallonsSubsequent to the sampling during the RI, tanks UST4 and

UST5 were apparently flooded with water and no longer contain anyfuel. Subsurface soil samples around the USTs for petroleumhydrocarbons, lead, benzene, toluene, and xylenes do not indicatethe presence of any significant leaks from these USTs.5 . 4 . 7 Off-site Rocky Branch Creek and Bayou Meto Flood Plain

SoilsOne element of the 1990 Off-site ROD called for the

excavation of floodplain areas that are currently zonedresidential where the TCDD concentrations are greater than 1 ppb.Approximately 4,100 cubic yards of soils are estimated to containdioxin above the cleanup goal. The highest TCDD concentrationfound in this area was 9 . 6 ppb. The remedy in the 1990 ROD alsocalled for these soils to be brought back to the Vertac site foron-site incineration. EPA subsequently deferred the treatmentrequirement for these soils such that all site soils could be

33

handled in a consistent manner. The remediation of these soils ufhas now been incorporated into this ROD. For more information ^—}see the Record of Decision, Vertac Superfund site - Off-site j>»Areas, September 1990. C<1

05 . 4 . 8 Residential Bagged Soils Cx

fIn 1988, EPA signed an Administrative Order on Consent (AOC) '

with Hercules, requiring them to remove soils from residentialyards south of the Vertac plant where TCDD was found above 1 ppb,and a drainage ditch on-site in the area of the residences.Approximately 2,770 cubic yards of soils were bagged and placedin a storage facility at the site. Chlorinated phenols,chlorinated benzenes, and chlorinated phenoxyherbicides werepresent at non-detect to low concentrations. TCDD was detectedin all samples at levels ranging from 13 ppb to 55 ppb. The1993 ROD for Vertac On-site Operable Unit 1 (above ground media)deferred the treatment requirement for these soils such that allsite soils could be handled in a consistent manner. Theremediation of these soils has now been incorporated into thisROD. For more information see the Record of Decision, VertacSuperfund site - Operable Unit 1, June 1 9 9 3 .5 . 4 . 9 Sludges and Sediments from the Old Sewage Treatment Plant

DigesterOne element of the Record of Decision for the Vertac Off-

site Areas, September 1990, called for cleanup and demolition ofthe old Sewage Treatment Plant. As a part of this ROD,approximately 890 cubic yards of sludge and sediments from thesludge digester would be removed using a vacuum pumping systemand dewatered to approximately 300 cubic yards as a final volume.The dewatered sludges would then be transported back to theVertac site for on-site incineration. The maximum concentrationof TCDD found in the sludge digester sediments was 12.5 ppb. EPAsubsequently deferred the treatment requirement for these sludgesand sediments such that all site soils could be handled in aconsistent manner. The remediation of these sediments will nowbe incorporated into this Proposed Plan. For more informationsee the Record of Decision, Vertac Superfund site - Off-siteAreas, September 1990.6 . 0 SUMMARY OF SITE RISKS

6 . 1 RISK ASSESSMENT DESCRIPTIONAn evaluation of the potential risks to human health and the

environment from site contaminants associated with Operable Unit2 media were presented in a separate document called the OU2Baseline Risk Assessment. The baseline risk assessment wascompleted in concert with the development of the RI/FS. Thepurpose of the baseline risk assessment is to evaluate the

34

..^ -•.atf^*c.-^4potential risk to human health and the environment from site ^contaminants prior to remediation. The results from the baseline risk assessment are used to establish cleanup goals for the {*—contaminants at the site that pose the greatest risk. The OU2 c<lbaseline risk assessment is divided into two main sections, they oare; the Human Health Risk Assessment, and the Ecological Risk c-<Assessment. •

J

In general, a risk assessment is a procedure which uses acombination of facts and assumptions to estimate the potentialfor adverse effects on human health and the environment fromexposure to contaminants found at a site. The environmental orecological risk assessment is conducted to determine if there areany current or potential impacts on ecological receptorsattributable to the unremediated site. Human health risks aredetermined by evaluating known chemical exposure limits andactual concentrations at the site as identified during the RIsampling activities. In the risk assessment, carcinogenic risks(from chemicals that are known or believed to cause cancer) andnon-carcinogenic health risks (from chemicals that do not causecancer, but can cause a range of other illnesses) are calculated.6 . 2 IDENTIFICATION OF CHEMICALS OF CONCERN

This section summarizes the site data that were used toevaluate potential health risks to human and nonhuman receptors.The substances that were considered for each exposure mediuminclude the following:

• Surface Soil - ChlorophenolsChlorophenoxyherbicides

- 2,3,7,8-TCDD

• Ground Water - AcetoneChloroformChlorophenolsChlorophenoxyherbicidesMethylene ChlorideNitroaromatic explosivesPriority pollutant metals

- 2,3,7,8-TCDDTetrachlorobenzeneToluene

• Surface Water - ChlorophenolsChlorophenoxyherbicides

- 2,3,7,8-TCDDToluene

An effort was made to focus the risk assessment on thosechemicals that are greatest concern for a given medium.Chemicals that were infrequently detected in a medium that was

35

•».* '--

sampled systematically, unless there was evidence for a "hot ?*-spot" were eliminated (see U . S . EPA guidance, 1989 ( b ) ) . <r

Is-Tables 3, 4, and 5 presents the data summary for substances c

of potential concern for each medium and their frequency of ®detection. However, when evaluating the combined risk posed by <—'all the COCs at the site, dioxin contributed over 9 9 percent ofthe total risk.6 . 3 HUMAN HEALTH RISK ASSESSMENT

6 . 3 . 1 SummaryA baseline risk assessment was conducted for the Vertac site

where risks were evaluated using current site conditions forthree potential receptor scenarios: teenage trespasser, currentunprotected worker, and future unprotected worker. Exposureroutes assessed for the trespasser scenario included dermalcontact with soil, incidental ingestion of soil, contact withsurface water, and inhalation of particulates or vapors.Exposure routes accessed for the current unprotected workerscenario included incidental ingestion of soil, dermal contactwith soil, dermal contact with surface water and water from theproduction outfalls at the site, and the inhalation of airborneparticulates and vapors. A future unprotected worker was assumedto be exposed to the same substances of concern as the currentunprotected worker with the addition of the ingestion of siteground water. It should be noted, however, that the cleanup goalproposed by EPA for the site does not consider that a futureworker will be consuming ground water. Public water supplies arereadily available and the future use of site ground water as adrinking water source will be prohibited through administrativecontrols.6 . 3 . 2 Exposure Assessment

The potentially exposed populations and the pathways throughwhich they could be exposed for current and future siteconditions are discussed below.Current and Future Land Use

The land occupied by the Vertac facility is zonedcommercial/industrial. At present there are no manufacturingoperations at the site. Continuing activities include generalmaintenance of the plant, maintenance of previous remedies, andoperation of a ground water treatment plant by PRP sitemaintenance workers.

The land located west and north of the plant is also usedfor commercial/industrial purposes. Residential areas arelocated directly east and south of the plant. Deed restrictions

36

Substances of Potential Concern in SoilData Summary — All Samples

Substance

2-Chlorophenol2.4-D2 4-Dichlorophenol2,6-DichlorophenolSilvex245-T2,3,7,8-TCDD

Tetrachlorobenzene'1

2-4.5-Trichlorophenol

Frequencyof

Detection"

19/138122/12777/13833/138105/124125/129

443/1,146

1/153/13753/136

Range ofSample

QuantitationLimits

(mg/kgy0.33-18

0.023-4.20.042-180.33-18

0.012-6700.012-6700.01-4.5(ng/g)

N10.33-3.81.7-91

Range ofDetected

Concentrations(mg/kg)^0.047-3.0

0.0053-5,5000.034-3600.066-15

0.0012-2900.0016-7100.04-2.200

(ng/g)670,000

0.033-2700.047-79

AdjustedGeometric

MeanConcentration

0.34580

3.00.54

28635.3

(ng/g)NA

1.92.6

Upper 95%Confidence Limitof the Geometric

MeanConcentration

(mg/kg)^0.39

3,1005.00.66

110250

9.2(ng/g)

NA3.03.4

NA = Not applicableN1 = Information was not available•Ratio of the number of sampling locations at which the substance was detected to the total number of sampling locations with the exceotion of2,3,7,8-TCDD. The frequency of detection for 2,3,7,8-TCDD is the ratio of the number of composite samples in which 2,3 7 8-TCDD was detected »nthe total number of composite samples. ' ' wioucu in

•With the exception of 2,3,7,8-TCDD, which is expressed in units of ng/g.Includes "J" values, which are estimated below the minimum sample quantitation limit."These data are evaluated in the hot spot analysis (Subsection 3.5). - - r n o c y - 1 0" I U & I 10

Substances of Potential Concern in GroundwaterData Summary — Atoka Formation

Substance

OrganicsAcetoneChloroform2-Chlorophenol4-Chlorophenol

2,4-D2,6-D2,4-Dichlorophenol2.6-DichlorophenolMethylene chloride

PhenolSilvex2.4.5-T2,4,6-T2,3,7,8-TCDD

Tetrachlorobenzene

Toluene2,3,6-Trichlorophenol2.4,5-Trichlorophenol

Frequency ofDetection'

5/153/1534/7638/8052/8535/4743/8135/812/1520/4741/8545/8531/479/39

12/3041/8519/8044/81

(Range of) SampleQuantitation Limit(s)

(•ng/L)"

0.0021-0.110.005-0.050.005-0.0550.005-0.0140.0001-0.027

0.0050.005-0.060.005-0.820.005-0.063

0.0050.0005-0.54

0.00013-0.0070.005

0.01-1.8(ng/L)

0.01-0.400.001-0.820.005-0.820.005-4.1

Range of DetectedConcentrations

(mg/L)^

0.009-0.0300.002-0.0300.002-66.70.001-61.4

0.00015-1,6400.006-1,1000.0012-5970.001-90.10.022-0.100.001-10

0.00036-1100.0001-3800.004-2100.85-2.080

(ng/L)0.008-2.90.002-4400.002-8.920.002-411

Adjusted GeometricMean Concentration

(mg/L)"

0.00950.0049

3.013

4,200''10,000'

554.4

0.00771.023

430'230'13

(ng/L)0.0411,100'0.048

19

Upper 95% ConfidenceLimit of the Geometric

Mean Concentration(mg/L)-

0.0160.0071

16100'

160,000'2,000,000'

58025

0.0137.6230'

11,000'8,700'

97(ng/L)0.10

29,000'0.095130

- - C 0 2 7 1 9

Substances of Potential Concern in GroundwaterData Summary — Atoka Formation

(continued)

Substance

Organics (continued)2,4,6-TrichlorophenolInofganicsAntimonyArsenicChromiumCopperLeadMercuryNickelSilver

Frequency ofDetection*

38/80

3/262/265/263/262/269/2610/1811/264/2622/22

(Range of) SampleQuantitation Limit(s)

(mg/L)'

0.005-0.82

0.0600.0100.0100.0250.003

0.0002-0.000250.0400.010

0.010-0.100.020*

Range of DetectedConcentrations

(mg/L)-'

0.001-94

0.022-0.0290.0036-0.0130.0020-0.0120.0066-0.0250.0036-0.011

0.00022-0.000760.011-0.109

0.0034-0.00940.010-0.1000.011-0.270

Adjusted GeometricMean Concentration

(mg/L)"

2.1

0.0290.00530.00500.0130.00180.000230.0320.00560.0310.043

Upper 95% ConfidenceLimit of the Geometric

Mean Concentration("g/L)-

9.9

0.030"0.00560.00550.0140.00210.000310.0490.00600.0600.063

•Ratio of the number of wells in which the substance was detected during one or more sampling rounds to the total number of wells sampled.•With the exception of 2.3,7,8-TCDD, which is expressed in units of ng/L.Includes "J" values, which are estimated concentrations, usually below the minimum sariple quantitation limit."Exceeds the maximum reported concentration (Subsection 2.1).'Sample quantitation limits were not available. The contract-required detection limit/instrument detection limit (CRQL/IDL) is indicated.

-C02720

Substances of Potential Concern in Surface WaterData Summary — All Sample Locations

Substance

2-Chlorophenol4-Chlorophenol

2,4-D2,6-D2.4-Dichlorophenol2.6-Dichlorophenol

PhenolSilvex245-T*"i*^ l

2.4.6-T2.3,7,8-TCDD

Toluene

Frequency ofDetection*

6/66/66/66/66/66/66/66/66/66/63/6

6/6

Range ofSample

QuantitationLimits(^/L)"0.8-51.1-52-52-51-5

0.5-500.6-51-21-21-2

2-10(ng/L)5-21

Range of DetectedConcentrations

WL)^0.85-4601.2-8,800

2.9-17,0002.0-5,4001.8-6,8001.0-1,1000.60-6201.0-1,1001.7-3,3001.1-11,000

2.0-12(ng/L)

0.022-3.900

AdjustedGeometric

MeanConcentration

(wW18

2301,1005002001324842002401.6

(ng/L)52

Upper 95%Confidence Limitof the Geometric

MeanConcentration

(^/L)"420

480,000<1

^OO.OOO'1

45.000-290,00(y1

3504.60011

18,00011

44,000d

33.00(y1

1.9(ng/L)9,9ow1

-C02721

Substances of Potential Concern in Surface WaterData Summary — All Sample Locations

(continued)

Substance

2,3,6-Trichlorophenol2,4,5-Trichlorophenol2,4,6-Trichlorophenol

Frequency ofDetection"

5/66/66/6

Range ofSample

QuantitationLimitsWL)"1.2-501.5-51.1-5

Range of DetectedConcentrations

WL)^2.0-69

1.6-5,0001.7-1.500

AdjustedGeometric

MeanConcentration

WL)-4.113029

Upper 95%Confidence Limitof the Geometric

MeanConcentration

WL)"12

350,00011

2,50ff1

•Ratio of the number of sampling locations at which the substance was detected to the total number of sampling locations.•With the exception of 2,3,7,8-TCDD, which is expressed in units of ng/L.Includes "J" values, which are estimated below the minimum sample quantitation limit."Exceeds the maximum reported concentration (Subsection 2.1).

-C02722

, (,".9> "W"'r^ rl• • •&a '- ,ws»-*"" CT.)are in place that will prevent future residential development of G lthe site. Additional deed restrictions will be sought to limit !>•future commercial development of portions of the site that will ^contain waste disposal'areas. ®<-

Based on current and probable future land uses, three 'receptors were evaluated: a trespasser, a current unprotectedworker, and a future unprotected worker. Trespassers and workersare the most likely future receptors at the site and representthose individuals with the highest potential for exposure to siterelated substances of concern.

Although the site is locked and fenced a trespasser couldenter the 200 acre site un-noticed by either climbing or crawlingunder one of the fences either currently or in the future. Ateenager between 12 and 18 years of age was evaluated.

Current and future worker scenarios were also evaluated.Because this site is zoned commercial/industrial, a maintenanceworker is the individual who has the greatest potential tocontact on-site media on a regular basis, both currently and inthe future.Potential Exposure PathwaysTrespasser

It is possible for a trespasser to be exposed to substancesof concern on the site through contact with soil, surface water,and air. Potential soil exposure routes include dermal contactand incidental ingestion of soil.

Of the on-site surface waters, a trespasser is most likelyto come into contact with Rocky Branch Creek, which is locatedwithin the western margin of the site. Due to shallow nature ofthe creek, approximately 1 foot, only dermal contact wasevaluated. The potential for a trespasser to come into contactwith outfalls that flow to Rocky Branch Creek, was considered tobe unlikely, due to the fact that they flow only during periodsof high rainfall.

The trespasser could also be exposed to chemicals of concernthrough the inhalation of airborne substances originating fromsurface soil and surface water (particulate and/or vapor).

The potential for a trespasser to become exposed to siteground water was considered to be remote. Even if ground waterwere to be used on the-site in the future, it is likely that theground water would be used only after treatment. Thus, thisexposure pathway was not evaluated.

42

^ yi -. JW^-^..'a « 1C<1Current Unprotected Worker i-s,CMThe current unprotected worker was assumed to be exposed to Q

substances of potential concern through the same exposure routes <as the trespasser: incidental ingestion of soil, dermal , .absorption of soil, dermal absorption from surface water, and » •inhalation of airborne soil and vapors. However, the on-siteworker could also potentially come into contact with all on-sitesurface waters, including outfalls, on a regular basis. Contactcould occur during performance of general maintenance activities.

Because ground water has no current on-site uses, thecurrent worker has limited potential for contact with groundwater. Thus, the ground water pathway was not evaluated.Future Unprotected Worker

The future unprotected worker was assumed to be exposed tothe substances of potential concern through the same exposureroutes as the current unprotected worker, with the addition ofthe ingestion of site ground water. Ground water is currentlynot used as a drinking water source for the site, and it isunlikely that it will be used as such in the future because ofthe availability of public water. Conservatively, this pathwaywas evaluated, but EPA did not include this exposure route indeveloping remediation goals for the site.

A summary of the exposure pathways used for quantitativeevaluation is shown in Figure 10. Models used to calculateintakes, i . e . , doses, of the substances of concern for eachreceptor through the various exposure routes are shown in Tables6 . 7, 8, 9 , 10, and 11.6 . 3 . 3 Toxicity Assessment

The toxic effects of a chemical generally depend upon thelevel of exposure ( d o s e ) , the route of exposure (oral,inhalation, dermal), and the duration of exposure (acute,chronic, subchronic, or lifetime). Thus, a full description ofthe toxic effects of a chemical includes a listing of whatadverse health effects the chemical may cause (carcinogenic andnoncarcinogenic), and how the occurrence of these effects dependsupon dose, route, and duration of exposure.

Slope factors (SFs) have been developed by EPA forestimating excess lifetime cancer risks associated with exposureto potentially carcinogenic contaminants of concern. SFs, whichare expressed in units of (mg/kg-day)'1, are multiplied by theestimated intake of potential carcinogen, in mg/kg-day, toprovide an upper-bound.estimate of the excess lifetime cancerrisk associated with exposure at that intake level. The term"upper bound" reflects the conservative estimate of the risks

43

POTENTIALEXPOSURE

ROUTE

RELEASEMECHANISMSOURCE

RELEASEMECHANISM

SOURCE SOURCE

WATER U | DERMAL L-_fS^Lr- tM

...V "DISCHARGE" \ '

I Exposure pathway to receptor' cannot be completedU Exposure route Is highly unlikely

I———J DERMAL|——fI CONTACT I ILEGEND: ,••••• Pathway

:•. uncertainX Exposure route wasquantitatively evaluated

0 Exposure route wasqualitatively addressed

S Safety Issue; not addressedNOTES: * - System Includes leachate collection - french

drains and water treatment plantIn risk assessment

INHALATION

INHALATION

INGEST (ON

DERMAL| fCONTACT I I

INHALATION

INQE8TION

DERMAL|——|——,7PONTAQT I I — — u

INHALATION

INQESTION

DERMAL| fCONTACT I [

INQESTION

CONCEPTUAL MODEL OF POTENTIAL EXPOSURE ROUTES

VAPOR |__(——i———|fINHALATION I I — — — ! — — — I I

C02725

F / - ~ iy-'. , .

Model for Calculating Doses through theIncidental Ingestion of Soil

Soil Ingestion Dose CS * SIR * EF * ED(mg/kg-day) ' BW • AT

Where:

CS = Chemical concentration in surface soil (nig/kg)SIR = Soil mgestion rate (kg/day)EF = Exposure frequency (days/year)ED = Exposure duration (years)BW = Body weight (kg)AT = Averaging time (days)

Exposure AssumptionsAll Scenarios:CS = Surface soil exposure concentrationsTrespasser:SIR = 5.0E-05 kg/day (U.S. EPA, 1994a)EF = 1 day/week, 26 weeks/yearED == 5 yearsBW = 56 kg, average weight of a 12-to 18-year old (U.S. EPA, 1989a)AT = 365 days/year x 5 years (for evaluating noncancer risk)

= 365 days/year x 70 years (for evaluating cancer risk)Worker (Current and Future):SIR = 5.0E-05 kg/day (U.S. EPA, 1991)EF = 250 days/year (U.S. EPA, 1991)ED = 25 years (U.S. EPA, 1991)BW = 70 kg (U.S. EPA, 1991)AT = 365 days/year x 25 years (for evaluating noncancer risk)

= 365 days/year x 70 years (for evaluating cancer risk)

TABLE 6

Model for Calculating Doses throughDermal Absorption from Soil

SoU Dermal Absorption Dose CS * SA * AF ' ABS (or RABS) * EF * ED(mg/kg-day) s BW • AT

Where:CS = Chemical concentration in surface soil (mg/kg)SA = Skin surface area available for contact (cm2/day)AF = Soil-to-skin adherence factor (kg/cm2)ABS = Absorption factor (unitless)RABS = Relative dermal absorption factor (unitless)EF = Exposure frequency (days/year)ED = Exposure duration (years)BW = Body weight (kg)AT = Averaging time (days)

Exposure AssumptionsAll Scenarios:CS = Surface soil exposure concentrationsAF = l.OOE-06 kg/cm2, reasonable upper limit of soil adherence factor (U.S.

EPA, 1992a)ABS = 0.03 for dioxin (U.S. EPA, 1992a)RABS = 0.50 for all chemicals except dioxin, based on guidance in U.S. EPA, i<)89cTrespasser:SA = 1,950 cn^/day, based on the average arm and hand surface area of a 12- to

18-year old (U.S. EPA, 1989a)EF = 1 day/week, 26 weeks/yearED = 5 yearsBW = 56 kg, average weight of a 12- to 18-year old (EPA, 1989a)AT = 365 days/year x 5 years (for evaluating noncancer risk)

= 365 days/year x 70 years (for evaluating cancer risk)

TABLE 7

... '•'•«',•. ''*- '-'---- t.,

rv-:r^ fe

Model for Calculating Doses throughDermal Absorption from Soil

(continued)

Worker (Current and Future):

SA = 2,000 oaf/day, based on the average arm and hand surface area of adultmales (U.S. EPA, 1989a)

EF =250 days/year (U.S. EPA, 1991)

ED =25 years (U.S. EPA, 1991)

BW = 70 kg (U.S. EPA, 1991)

AT = 365 days/year x 25 years (for evaluating noncancer risk)= 365 days/year x 70 years (for evaluating cancer risk)

TABLE 7 (cont)

.... 'Y-- i. . - • . ' ^^ t!ts „•• .-'•^ K( "

Model for Calculating Doses through theInhalation of Airborne Soil

Soil Inhalation Dose CS * RD * IV ' EF * ED(mg/kg-day) = BW • AT

Where:CS = Chemical concentration in surface soil (mg/kg)RD = Respirable-size soil particle concentration in air (i.e., PMio) (kg/m3)IV = Inhalation volume (mVday)EF = Exposure frequency (days/year)ED = Exposure duration (years)BW = Body weight (kg)AT = Averaging time (days)

Exposure AssumptionsAll Scenarios:CS = Surface soil exposure concentrationsRD = 3.1E-08 kg/m3 (URS, 1990)Trespasser:IV = 2.5 mVday, based on 1 hour of moderate activity on the site (U.S. EPA,

1989a)EF = 1 day/week, 26 weeks/yearED = 5 yearsBW = 56 kg, average weight of a 12- to 18-year old (U.S. EPA, 1989a)AT = 365 days/year x 5 years (for evaluating noncancer risk)

= 365 days/year x 70 years (for evaluating cancer risk)

TABLE 8

s-- ' '.«?-'S)*t • -\ '•,.0 ,t

•e^^ -:' .; i :., " »; fl,

w»"^'"

Model for Calculating Doses through theInhalation of Airborne Soil

(continued)

Worker (Current and Future):

IV = 2 0 m^day (U.S. EPA, 1991)

EF =250 days/year (U.S. EPA, 1991)

ED = 25 years (U.S. EPA, 1991)

BW = 70 kg (U.S. EPA, 1991)

AT = 365 days/year x 25 years (for evaluating noncancer risk)= 365 days/year x 70 years (for evaluating cancer risk)

TABLE 8 (cont)

Model for Calculating Doses through theInhalation of Vapors

Vapor Inhalation Dose CA * IV * EF ' ED(mg/kg-day) ° BW • AT

Where:CA = Chemical vapor concentration in air (mg/m3)IV = Inhalation volume (mVday)EF = Exposure frequency (days/year)ED = Exposure duration (years)BW = Body weight (kg)AT = Averaging time (days)

Exposure Assumptions

All Scenarios:CA = Vapor concentrationsTrespasser:IV = 2.5 m'/day, based on 1 hour of moderate activity on the site (U.S. EPA,

1989a)EF = 1 day/week, 26 weeks/yearED = 5 yearsBW = 56 kg, average weight of a 12- to 18-year old (U.S. EPA, 1989a)AT = 365 days/year x 5 years (for evaluating noncancer risk)

= 365 days/year x 70 years (for evaluating cancer risk)Worker (Current and Future):IV = 20 mVday (U.S. EPA, 1991)EF = 250 days/year (U.S. EPA, 1991)ED = 25 years (U.S. EPA, 1991)BW = 70 kg (U.S. EPA, 1991)AT = 365 days/year x 25 years (for evaluating noncancer risk)

= 365 days/year x 70 years (for evaluating cancer risk)

TABLE 9

Model for Calculating Doses throughDermal Absorption from Surface Water

Surface WaterDermal Absorption Dose = CSW » CF-1 * SA ' PC ' ET * CF-2 * EF ' ED

(mg/kg-day) BW • ATWhere:CSW = Chemical concentration in surface water (mg/L)CF-1 = Conversion factor (mg//Jg)SA = Skin surface area available for contact (cm2)PC = Dermal permeability coefficient (cm/hour)ET = Exposure time (hours/day)CF-2 = Conversion factor (L/cm3)EF = Exposure frequency (days/year)ED = Exposure duration (years)BW = Body weight (kg)AT = Averaging time (days) ____Exposure AssumptionsAll Scenarios:CF-1 = lmg/l,000^gPC = Permeability coefficientCF-2 = IL/l.OOOcm3

Trespasser:CSW = Surface water exposure concentrations for Rocky Branch Creek, presented

in Table 3-2SA = 1,970 cm2, average hand and foot surface area of a 12- to 18-year old (U.S.

EPA, 1989a)ET = 1 hour/dayEF = 1 day/week, 13 weeks/yearED = 5 yearsBW = 56 kg, average weight of a 12- to 18-year old (U.S. EPA, 1989a)AT = 365 days/year x 5 years (for evaluating noncancer risk)____= 365 days/year x 70 years (for evaluating cancer risk)

TABLE 10

Model for Calculating Doses throughDermal Absorption from Surface Water

(continued)

Worker (Current and Future):CSW = Surface water exposure concentrations based on all surface waters,

presented in Table 3-2SA =840 cm2, average hand surface area of an adult (U.S. EPA, 1989a)ET = 1 hour/dayEF = 1 day/week, 50 weeks/year (U.S. EPA, 1991)ED = 25 years (U.S. EPA, 1991)BW = 70 kg (U.S. EPA, 1991)AT = 365 days/year x 25 years (for evaluating noncancer risk)___= 365 days/year x 70 years (for evaluating cancer risk) ___

TABLE 10 (cont)

r--^ ?U1 iv'-"' '"

Model for Calculating Doses through theIngestion of Groundwater

Groundwater Ingestion Dose CGW * GIR * EF * ED(mg/kg-day) - BW • AT

Where:CGW = Chemical concentration in groundwater (mg/L)GIR = Groundwater mgestion rate (L/day)EF = Exposure frequency (days/year)ED = Exposure duration (years)BW = Body weight (kg)AT = Averaging time (days)

Exposure AssumptionsWorker (Future):CW = Groundwater exposure concentrationsIR = 1 L/day (U.S. EPA, 1991)EF = 250 days/year (U.S. EPA, 1991)ED = 25 years (U.S. EPA, 1991)BW = 70 kg (U.S. EPA, 1991)

AT = 365 days/year x 25 years (for evaluating noncancer risk)365 days/year x 70 years (for evaluating cancer risk)

TABLE 11

calculated from the SF. Use of this approach makes *underestimation of the actual cancer risk unlikely. Slope cfactors are derived from the results of human epidemiological ^*studies or chronic animal bioassys to which animal-to-human "-extrapolation and uncertainty factors have been applied. °

References doses (RfDs) have been developed by EPA for ^indicating the potential for adverse health effects from exposureto contaminants of concern exhibiting non-carcinogenic adversehealth effects. RfDs which are expressed in units of mg/kg-day,are estimates of daily (maximum) exposure levels for the humanpopulation, including sensitive subpopulations. Estimatedintakes of contaminants of concern from environmental media( e . g . , the amount of chemical ingested from drinking contaminatedground water) can be compared to the RfD. RfDs are derived fromhuman epidemiological studies or animal studies to whichuncertainty factors have been applied to account for the use ofanimal data to predict effects on humans.

Toxicity information used to calculate the risk forcarcinogenic risk including the slope factor, the weight ofevidence, and source of the toxicity information can be found inTables 12 and 13. Chronic and subchronic references doses usedin the toxicity assessment can be found in Tables 14 and 15.

In numerous public forums over the past year, EPA hassummarized the preliminary results from the dioxin reassessmentstudy in order to accept public comment during the scientificpeer review process. One of the major conclusions was that the"weight-of-evidence" suggested that dioxin, furans, and dioxinlike compounds are likely to present a cancer hazard to humans,and that a risk specific dose of dioxin at 0.01 pico grams (pg)TEQ per kilogram (kg) of body weight per day, resulted in oneadditional cancer in one million. This risk specific doseestimate represents a plausible upper bound on risk based on theevaluation of both animal and human data. With regards toaverage intake, humans are currently exposed to background levelsof dioxin-like compounds on the order of 3-6 TEQs pg/kg/day.Therefore, plausible upper-bound risk estimates for generalpopulation exposures to dioxin and related compounds (atbackground levels) may be as high as 1 in 10,000 (1X10'4) to 1 in1,000 (1X10' 3) . High end estimates of body burden of individualsin the general population (approximately the top 10% of thegeneral population) may be greater than 3 times higher.

What should also be noted here is that the risk calculationspresented in the baseline risk assessment, and reported in thissummary for dioxin, are based on exposure to 2,3,7,8-TCDD only.Additional sampling performed by the PRP at the request of EPAshows that other dioxin and furan compounds are present at thesite, and could contribute to approximately 20 percent greaterrisk than TCDD alone, i . e . , the risk estimates presented could be

54

U.S. EPA and IARC Categorizations of the CarcinogenicSubstances of Potential Concern

Substance

OrganicsChloroformMethylene chloride2 ,7.8-TCDD2,4,6-TrichlorophenolInofganicsArsenicLead

EPACardnogenicity

Category"'"

B2CB2B2

AB2

IARCCardnogenidty

Category^

2B2B2BNC

12B

•References: KIS, 1995; VS. EPA, 19946"Category definitions (VS. EPA, 1986b):

A = Human carcinogen (sufficient evidence from epidemiologic studies).B2 = Probable human carcinogen (sufficient evidence from animal studies and inadequate or no human

data).C = Possible human carcinogen (limited evidence from animal studies and no human data)

'Reference: WHO, 1987"Category definition (WHO, 1987):

1 = Human carcinogen (sufficient evidence of cardnogenidty in humans).2B = Possible human carcinogen (limited evidence of cardnogenidty in humans in the absence of

suffident evidence of cardnogenidty in experimental animals; inadequate evidence of cardnogenidtyin humans or no human data and suffident evidence of cardnogenidty in experimental animals; orinadequate evidence of cardnogenidty or no data in humans and limited evidence of cardnogenidtyin experimental animals with supporting evidence from other relevant data).

NC = Not categorized.

TABLE 12

Cancer Slope Factors

Substance

ChymesChloroform

Mcthylene chloride

2A7.8.TCDD

2.4,6-Trichlorophcnol

Inorymucs

Arsenic

Lead

InhalationSlope Factor(mg/kg-day)'1

NC

NC

L5E+Q5

9.7E+03

1.1E-02"

NC

NC

Referenceor Basis

—

—

U.S.EPA,1994b

OSF

IRIS, 1995

—

—

Oral SlopeFactor

(mg/kg-day)-1

6.1E-03

7.5E-03

L5E+05

9.7E+03

1.1E-02

1.75E+W

NTV

Referenceor Basis

IRIS, 1995

IRIS, 1995

U.S.EPA,1994b

ChfinRkIc,1990

IRIS, 1995

IRIS, 1995

-

Dermal SlopeFactor*

(mg/kg-day)'1

NC

NC

3.0E+05

1.9E+04

Z2E-02

NC

NC

'Dermal slope factors were derived from the oral slope factors as described in Subsection 3323.'Derived from a unit ride, ai«nming fhf. inhal^rm nf 7Q m3 nf ajr pfr Ayy »ni\ y bo^y wmgh* nf 70 leg (I T S RPA,1994b).

"Derived from a unit risk, assuming the consumption of 2 liters of water per day and a body weight of 70 kg(U.S. EPA, 1994b).

NC = Substance is not of concern through this exposure route.NTV = A toxidty value was not available.OSF = Oral slope factor was used (Subsection 33.2.2).

TABLE 13

Chronic Reference Doses (RfDs)

Substance

Orsanics

Acetone

Chloroform

2-Chlorophcnol

4-Chlorophenol

2,4-D

2,6-D

2,4-Dichlorophenyl

2,6-Dichlorophenyl

Methylene chloride

Phenol

Silvex

2.4,5-T

2.4.6-T

2.3.7.8-TCDD

Tetrachlorobenzene

Toluene2,3,6-Trichlorophenol

Inhalation RfD(mg/kg-day)

NC

NC

5.0E-03

NC

l.OE-02

NC

3.0E-03

3.0E-03

NC

NC

8.0E-03

l.OE-02

NC

NTV

3.00E-04t>

NC

NC

Referenceor Basis

—

—

ORD

—

ORD

—

ORD

ORD

—

—

ORD

ORD

—

ORD

—

—

Oral RfD(mg/kg-day)

l.OE-01

l.OE-02

5.0E-03

5.0E-03

l.OE-02

l.OE-02

3.0E-03

3.0E-03

6.0E-02

6.0E-01

8.0E-03

l.OE-02

l.OE-02

NTV

3.0E-04'

2.0E-01

l.OE-01

Referenceor Basis

IRIS, 1995

IRIS, 1995

IRIS, 1995

Isomer

IRIS, 1995

Isomer

IRIS, 1995

Isomer

BUS, 1995

IRIS, 1995

IRIS, 1995

IRIS, 1995

Isomer

—

IRIS. 1995

IRIS, 1995

Isomer

Dermal RfD*(mg/kg-day)

NC

NC

4.5E-03 (dw)

4.5E-03 (dw)

5.0E-03 (d)

5.0E-03(d)

2.7E-03 (dw)

2.7E-03 (dw)

NC

5.4E-01 (g)

4.0E.03 (d)

5.0E-03 (d)

5.0E-03(d)

NTV

NC

1.8E-01 (g)

5.0E-02 (d)

C02738

Chronic Reference Doses (RfDs)(continued)

Substance

Organics (continued)2,4,5-Tnchlorophcnol

2.4.6-Trichlorophenol

Inofganics

Antimony

Arsenic

Copper

Lead

Mercury

Nickel

Silver

Thallium

Inhalation RfD(mg/kg-day)

l.OE-01

l.OE-01

NC

NC

NC

NC

NC

NC

NC

NC

NC

NC

Referenceor Basis

ORD

ORD

—

—

—

—

—

—

—

—

—

Oral RfD(mg/kg-day)

l.OE-01

l.OE-01

4.0E-04

3.0E-04

5.0E-03"

3.7E-02'

NTV

3.0E-04

2.0E-02

5.0E-03

NTV

3.0E-01

Referenceor Basis

IRIS, 1995

Isomcr

IRIS, 1995

IRIS, 1995

DUS, 1995

U.S. EPA, 1994b

—

U.S. EPA, 1994b

IRIS, 1995

IRIS, 1995

—

IRIS, 1995

Dermal RfD*(mg/kg-day)

5.0E-02 (d)

5.0E-02 (d)

NC

NC

NC

NC

NC

NC

NC

NC

NC

NC

•Chronic dermal RfDs were calculated from the chronic oral RfDs as described in Subsection 3.3.3.3. The route by which the chemical was administeredin the studies on which the oral RfD was based is indicated in parentheses as follows:

d = dietdw = drinking waterg = gavage

'The inhalation RfD was used only in the hot spot analysis (Subsection 3.5).

: -002739

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1U§•I.4

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18»-i|UQ^

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fl

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l

i<fl

3»-i1»-<Q060»-i?W)

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s0»-1

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U21UZ12a'0(.«^

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l-l

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TAB

LE 15

Subchronic Reference Doses (RfDs)(continued)

Substance

Organics (continued)

2,4,5-Trichlorophenol

2,4,6-Trichlorophenol

Inhalation RfD(mg/kg-day)

l.OE+00

l.OE+00

Referenceor Basis

ORD

ORD

Oral RfD(mg/kg-day)

l.OE+00

l.OE+00

Referenceor Basis

VS. EPA, 1994b

Isomer

Dermal RfD*(mg/kg-day)

5.0E-01 (d)

5.0E-01 (d)

*Subchronic dermal RfDs were calculated from the subchronic oral RfDs as described in Subsection 3333. The route by which the chemical wasadministered in the studies on which the oral RfD was based is indicated in parentheses as follows:

ddwg

(D)

NCNTVORD

dietdrinking watergavageThe substance is not of concern for the trespasser scenario through the oral route.The oral RfD was used only to calculate the dermal RfD.The chemical is not a substance of potential concern through this exposure route.A toxicity value was not available.The subchronic oral RfD was used.

-C02741

adjusted upward by 20 percent.It is also important to note that the non-cancer risks

outlined in baseline risk assessment and summarized here do notaddress the noncancer risks associated with low level exposuresto dioxin. As a result, the baseline risk assessment mayunderestimate the noncancer risk associated with exposure to sitecontaminants. The reason being is that a reference dose (RfD)(the daily intake of a chemical to which an individual can beexposed without experiencing noncancer health effects) has notbeen established by EPA for dioxin at this time. If a referencedose were to be calculated for dioxin based on human and animaldata, it could result in an acceptable intake level for humansbelow the current level of daily intake in the generalpopulation. EPA's dioxin reassessment study has suggested thatat some dose, and possibly within one order of magnitude ofaverage background body burdens, dioxin exposure can result innoncancer health effects in humans. These effects includedevelopmental and reproductive effects, immune suppression, anddisruption of regulatory hormones.6 . 3 . 4 Risk CharacterizationCancer Risk

The risk of getting cancer from exposure to a chemical isdescribed in terms of probability that an individual exposed forhis or her entire lifetime will develop cancer by the age 70.For carcinogens, risks are estimated as the incrementalprobability of an individual developing cancer over a life-timeas a result of exposure to the carcinogen. Excess life-timecancer risk is calculated using the following equation:

Cancer Lifetime CancerRisk = Averaged x Slope

Dose Factor(mg/kg-day) (mg/kg-day)'1

These risks are probabilities that are generally expressedin scientific notation' ( e . g . , 1 x 10'6 or I E ' 6 ) . An excesslifetime cancer risk of 1 x 10'6 indicates that, as a reasonablemaximum estimate, and individual has a 1 in 1,000,000 chance ofdeveloping cancer as a result of site related exposure to acarcinogen over a 70-year lifetime under the specific exposureconditions at a site.

Tables 16, 17, and 18 summarize the potential lifetimecancer risk for the three exposure scenarios examined in the riskassessment.

The calculated excess lifetime cancer risk for thetrespasser scenario was 8X10'5 or approximately 8 in 100,000.

61

POTENTIAL LIFETIME CANCER RISKTRESPASSER

SUBSTANCE

2,3,7,8-TCBD (U.S. EPA)(ChcmRlak)

2.4,6-Trlchlofoph»nol

TOTAL (U.8.EPA)

TOTAL (Ch»mRi8f()

SOILINGESTION

4.05E-071.70E-10

6.27E-06

4.06E-07

DERMALABSORPTIONFROM SOIL

9.29E-073.31 E-09

1.47E-05

9.32E-07

SOILINHALATION

9.72E-096.28E-102.63E-13

9.72E-09

6.29E-10

VAPORINHALATION

1.94E-101.26E-112.50E-14

1.94E-10

1.26E-11

TOTAL LIFETIMECANCER RISK (U.S. EPA)

TOTAL LIFETIMECANCER RISK (Ch.mRl.ki 5.39E-06

———BERMAL |ABSORPTION

FROM SURFACEWATER

8.39E-064.05E-064.41 E-10

6.39E-05

TOTAL

8.48E-055.38E-063.92E-09

8.49E-05

POTENTIAL LIFETIME CANCER RISKCURRENT UNPROTECTED WORKER

SUBSTANCE

2,3,7,8-TCDD (U.S. EPA)(Ch«mRi«k)

2,4,6-TrlchlorophTiol

TOTAL (U.S. EPA)

SOILINGESTION

2.41 E-041.56E-056.53E-09

2.41E-04

1.56E-05

DERMALABSORPTIONFROM SOIL

5.79E-043.67E-051.31E-07

5.79E-04

3.6BE-0'6

SOILINHALATION

2.99E-061.93E-078.10E-11

2.99E-06

1.93E-07

VAPORINHALATION

5.98E-083.88E-007.69E-12

5.98E-08

3.87E-OB

TOTAL LIFETIMECANCER RISK (U.S. EPA) 1.29E-03

TOTAL LIFETIMECANCER RISK (ClwmRIck) 8.34E-05

DERMALABSORPTION

FROM SURFACEWATER

4.88E-042.97E-051.14E-06

4.70E-04

3.08E-05

TOTAL

1.29E-038.21 E-051.28E-06

- - f 0 2 7 4 4

POTENTIAL LIFETIME CANCER RISKFUTURE UNPROTECTED WORKER

SUBSTANCE

ChloroformMethytorr chloride2,3,7,8-TCDD (U.S. EPA)

(ChtmFUtk)2,4,6-Trichloroprrnol

Ar—nicLwad

TOTAL (U.S. EPA)

TOTAL fCh.mRl.M 1

SOILINGESTION

NANA

2.41E-041.56E-056.53E-09

NANA

2.41E-04

1.56E-05

DERMALABSORPTIONFROM SOIL

NANA

5.79E-043.67E-051.31E-07

NANA

5.79E-04

3.68E-05

SOILINHALATION

NANA

2.99E-061.93E-078.10E-11

NANA

2.99E-06

1.93E-07

VAPORINHALATION

NANA

5.98E-083.86E-097.69E-12

NANA

5.98E-08

. 3.87E-09

DERMALABSORPTION

FROM SURFACEWATER

NANA4.68E-042.87E-051.14E-06

NANA

4.70E-04

a.OBE-05

TOTAL LIFETIMECANCER RISK (U.S. EPA) 5.28E-02

TOTAL LIFETIMECANCER RISK (CrwmRI«M 3.78E-03

QROUNDWATERINQESTION

1.51E-073.41 E-075.08E-023.29E-033.81 E-04

3.42E-05NTV

5.13E-02

,3,70E-Q3

TOTAL

1.51E-073.41 E-075.21 E-023.37E-033.82E-04

3.42E-OSNTV

NA - Not applicable. Crrmlcal Is not of concern through this •xpcrur* route.NTV - Not calculated b«cau— a alop* tactor was not avallabte.

C02745

The exposure routes that posed the majority of the risk to the <trespasser was through dermal absorption from surface water, ^incidental soil ingestion, and dermal contact with soil. TCDD j^.dioxin was the only contaminant that contributed to an excess 0}cancer risk greater that 1X10'6. 0

The calculated excess lifetime cancer risk for the currentunprotected worker scenario based on all exposure routes wasapproximately 1 in 1,000 or 1X10'3. This risk exceeds EPA'sacceptable risk range. The exposure routes that posed themajority of the risk to the current unprotected worker wasthrough dermal contact with soil (6X10' 4) , dermal contact withsurface waters (5X10' 4) , and incidental soil ingestion (2X10'4) .

The calculated excess lifetime cancer risk for the futureunprotected worker scenario based on all exposure routes wasapproximately 5 in 100 or 5X10'2. This risk exceeds EPA'sacceptable risk range. The exposure routes that posed themajority of the risk to the future unprotected worker was throughsoil ingestion (2X10'4) , dermal contact with soil (6X10' 4) , dermalcontact with surface water (5X10'4) , and ground water ingestion(5X10" 2) .

Over 9 9 percent of the calculated risk for all exposurescenarios was contributed by 2 , 3 , 7 , 8 - T C D D . As mentioned earlier,when all dioxin and furan congeners are factored into the riskestimates, those estimates may be 20 percent higher.Noncancer Risk

The potential for'noncarcinogenic effects is evaluated bycomparing an exposure level over a specified time period ( e . g . ,life-time) with a reference dose derived for a similar exposureperiod. The ratio of exposure to toxicity is called the hazardquotient. By adding the hazard quotients for all contaminants ofconcern which affect the same target organ ( e . g . , the liver)within a medium or across all media to which a population mayreasonably be exposed, the Hazard Index (HI) can be generated.In general, a total hazard index of 1 is used as a benchmark ofpotential concern for noncancer health effects.

Hazard Daily ReferenceQuotient = Intake - Dose

Tables 19, 20, and 21 summarize the hazard quotients and indicescalculated for the same potentially exposed individuals.

The total hazard index calculated (for contaminants ofconcern other than dioxin) for a trespasser was approximately0 . 4 , based on soil ingestion, soil inhalation, dermal contactwith soil, and dermal contact with surface water. Again, thebenchmark of concern for noncancer health effects is 1. A total

65

<—» •

HAZARD QUOTIENTS AND INDICESTRESPASSER

SUBSTANCE

2-Chlorophtnol4-Chlofophenol2.4-D2 A n,o u2.4-Dlchlwophcnol2,6- DIchlofOphTio)PhwiolSllvx2,4,5-T2.4,6-T2,3,7.8-TCDDT»trachlorob»nz«n»Toluw2,3,6-Trlchlof0ph»nol2,4,5 -Triehlofophano)2,4,6 -Trlchlwoph«nol

HAZARD INDEX (BY EXPOSURE ROUTE) 1

SOILINQESTION

NA1.97E-02

NA1.06E-041.40E-05

NA8.75E-041.59E-04

NANTVNANANA

1.91E-072.16E-07

2.09E-02

DERMALABSORPTIONFROM SOIL

9.67E-06NA

3.84E-01NA

2.07E-032.73E-04NA

1.71E-023.10E-03NANTVNANANA

3.72E-064.22E-06

4.07E-01

SOILINHALATION

NA3.06E-05

NA1.64E-072.17E-08

NA1.36E-062.46E-07

NANTVNANANA

2.96E-103.35E-10

3.23E-05

VAPORINHALATION

1.S4E-10NANCNA

3.60E-086.04E-09NA5.96E-093.18E-09NANTVNANANA

5.09E-103.18E-11

,,5-,1»E-<»

TOTAL HAZARD INDEX 4.29E-01

DERMAL |ABSORPTION

FROM SURFACEWATER

1.60E-052.78E-048.ME-053.62E-042.22E-054.38E-089.96E-052.76E-051.55E-05

NTVNA

6.01 E-072.88E-071.58E-06S.62E-07

9.10E-04

HAZARD INDEX(BY

SUBSTANCE)

1.22E-051.60E-OS4.04E-018.88E-052.54E-033.09E-044.38E-081.80E-023.29E-031.55E-05

NTVNA

5.01 E-072.85E-075.49E-065.00E-06

NA- NotaoDllcabte. Chemical Is not of conc«rn through thl» •xposuf rout«.NC - Not criculafd b«cau- «n •xpo«ur« conc»ntratlon could not b* d.frmln.d (Appendix E).NTV - Not calculated becau— an RID waa not available.

C02747

HAZARD QUOTIENTS AND INDICESCURRENT UNPROTECTED WORKER

SUBSTANCE

2-ChlorophTiol4-ChlorophTiol2,4-02,6-02,4-Dlchlo»oph«nol2,6-Dlchlofopheno)PhenolSllvx2,4.5-T2,4,6-T2,3,7,8-TCDDT«trachlorob»nz»n«TolUTT2,3,6-Trlchloroph»nol2,4,5-Trlchloroph»nol2,4,6-Trlchloroprrnol

HAZARD INDEX (BY EXPOSURE .ROUTE)

SOILINGESTION

3.82E-05NA

1.52E-01NA

8.15E-041.08E-04

NA6.73E-031.22E-02

NANTVNANANA

1.47E-051.66E-05

1.72E-01

DERMALABSORPTIONFROM SOIL

7.63E-04NA

3.03E+00NA1.63E-022.15E-03NA

1.35E-012.45E-01NANTVNANANA

2.94E-043.33E-04

3.43E+00

SOILINHALATION

4.73E-07NA

1.68E-03NA

1.01E-051.33E-06

NAB.34E-051.52E-04

NANTVNANANA

1.82E-072.06E-07

2.13E-03

VAPORINHALATION

8.22E-08NANCNA

2.22E-063.72E-07NA

3.67E-071.96E-06NANTVNANANA

3.13E-071.96E-08

5.33E-06

TOTAL HAZARD INDEX 4.19E+00

DERMALABSORPTION

FROM SURFACEWATER

5.00E-031.16E-014.72E-021.80E-022.48E-013.09E-031.55E-051.20E-023.08E-027.WE-02

NTVNA1.60E-032.24E-058.61 E-032.91 E-03

5.79E-01

HAZARD INDEX(BY

SUBSTANCE)

5.86E-031.16E-013.23E+001.50E-022.66E-015.3SE-031.55E-051.53E-012.97E-017.99E-02

NTVNA1.60E-032.24E-056.92E-033.26E-03

NA - Not applicable. Chemical l« not of concTn through this •xpo«um route.NC - Not calculated b«cau— an •xpoaum concentration could not b« dwtermlrwd (App«ndlx E).NTV - Not calculated fcrcau— an RrD was not available.

-C02748

HAZARD QUOTIENTS AND INDICESFUTURE UNPROTECTED WORKER

SUBSTANCE

AcetoneChloroform2-Chlorophenol4-Chlorophenol2,4-02,6-D2,4-Dichlorophenol2,6-DlchlorophfwlMetnylene chloridePhenolSUvex2,4,5-T2,4,6-T2,3,7,8-TCDDTetaehlorobenzTieToluene2,3.6-Trlchlorophenol2,4,5-Trlchlorophenol2,4,6-Trlchlorophenot

AntimonyArsenicChromiumCopperLeadMercuryML*lr«lNICKwQllutfOIIVW

ThalliumZinc

HAZARD INDEX tW EXPOSURE ROUTE) 1

SOILINGESTION

NANA

3.B2E-05NA

1.52E-01NA

8.15E-041.08E-04

NANA

673E-031.22E-02

NANTVNANANA

1.47E-051.66E-05

NANANANANANANANANANA

1.72E-01

DERMALABSORPTIONFROM SOIL

NANA

7.63E-04NA

3.03E+00NA1.63E-022.15E-03NANA1.35E-012.45E-01NANTVNANANA

2.94E-043.33E-04

NANANANANANANANANANA

3.43E+00

SOILINHALATION

NANA

4.73E-07NA

1.88E-03NA

1.01E-051.33E-06

NANA

8.34E-051.52E-04

NANTVNANANA

1.82E-072.06E-07

NANANANANANANANANANA

2.13E-03

VAPORINHALATION

NANA

8.22E-06NANCNA

2.22E-063.72E-07NANA3.67E-071.96E-06NANTVNANANA

3.13E-071.96E-06

NANANANANANANANANANA

5.33E-06

DERMALABSORPTION

FROM SURFACEWATER

NANA5.0CE-031.16E-014.72E-021.50E-022.4BE-013.08E-03

NA1.56E-061.20E-023.08E-027.90E-02

NTVNA1.60E-032.24E-068.61 E-032.B1E-03

NANANANANANANANANANA

5.79E-01

TOTAL HAZARD INDEX 5.52E+03

QROUNDWATERINQESTION

1.87E-036.9SE-033.13E+011.19E+021.57E+031.06E+031.88E+038.15E+012.12E-031.24E-011.35E+023.72E+022.05E+02

NTV3.26E+002.15E+019.30E-031.27E+019.68E-01

7.08E-011.83E-011.08E-023.70E-03

NTV1.01E-022.40E-021.17E-02

NTV2.05E-03

5.52E+03

HAZARD INDEX(BY

SUBSTANCE)

1.57E-038.88E-033.13E+011.19E+021.S7E+031.06E+031.89E+038.15E+012.12E-031.24E-011.35E+023.72E+022.06E+02NTV3.26E+002.15E+019.32E-031.27E+019.72E-01

7.09E-011.83E-011.08E-023.70E-03NTV1.01E-022.40E-021.17E-02NTV2.05E-03

NA - Not applicable. Chemical Is not of concern through this exposure route.NC - Not calculated because an exposure concentration could not be determined (Appendx E).NTV - Not calculated because an RID value was not available.

0hazard index of approximately 4 was calculated for the current »unprotected worker with dermal contact with 2,4-D contributing y^,most of the risk. For the future unprotected worker a hazard ^index of 5,520 was calculated. The ground water ingestion Qpathway contributed most to the noncancer risk for the future r^unprotected worker. Again, EPA for this ROD, did not considerthe ground water ingestion exposure route in developing theremediation goals for this site, because drinking water for theJacksonville area is provided from sources near Little Rock, andit is doubtful that any wells on this property will ever be usedfor domestic purposes.6 . 3 . 5 Uncertainty Analysis

Within the Superfund process, baseline risk assessments aredeveloped to provide risk managers a numerical representation ofthe severity of contamination present at a site, as well as toprovide an indication of the potential for adverse public healtheffects. There are many inherent and imposed uncertainties inthe risk assessment process. Some of these uncertainties maycontribute to the under estimation of site risk others, in itsoverestimation.

Factors that Tend to Underestimate Exposure/Risk• Lack of RfDs or SFs for all chemicals of concern• Nonquantification of some exposure pathways• Exclusion of chemicals present but not detected

Factors that Tend to Overestimate Exposure/Risk• Use of conservative exposure assumptions• Use of conservative RfDs or SFs

Factors that could either Over or UnderestimateExposure/Risk• Use of 1/2 the detection limit• Possible occurrence of hotspots6 . 3 . 6 Central Tendency Exposure

In February 199 2 , a guidance memorandum from the DeputyAdministrator of EPA required that all Superfund risk assessmentsto evaluate both reasonable maximum exposure (RME) and centraltendency exposures. Exposure assumptions in the ROD up to thissection have been based on RME. The central tendency scenario,represents the risk from more of an "average" exposure (seeTable 2 2 ) . However, EPA wanted to more fully evaluate potentialrisk at this site by conducting a Monte Carlo modelling, which isdescribed more fully later in the Remediation Goals section ofthe ROD.

6 9

Summary of Potential Cancer Risks and Hazard Indices'Central Tendency Case

Scenario

Trespasser

Current Unprotected Worker

Future Unprotected Worker

Total Lifetime Cancer Risk1'

4E-06 (CnemRisk)7E-05 (U.S. EPA)1E-05 (CnemRisk)2E-04 (U.S. EPA)2E-04 (ChemRisk)2E-03 (U.S. EPA)

Total Hazard Index

2E-02

2E-01

2E+03

"Values are rounded to one significant figure."ChcrnRisk = Cancer risk was calculated using the slope factor for 2 ,7,8-TCDD developed by ChemRisk.VS. EPA = Cancer risk was calculated using the slope factors for 2 ,7,8-TCDD developed by U.S. EPA.

TABLE 22

6 . 4 ECOLOGICAL RISK ASSESSMENT 0Uft

The objective of the ecological risk assessment is to !>•identify and estimate the potential for adverse ecological Ceffects to terrestrial and aquatic flora and fauna from exposure ®to substances found in the soil and surface waters at the Vertac t—site, including Rocky Branch Creek.

In general, the approach for conducting the ecological riskassessment parallels that used in the human health riskassessment. Habitats and organisms potentially affected by site-related chemicals were identified. For some organisms, the riskestimated was due to direct exposure to site chemicals, such asthrough ingestion of site surface water, and for other organismssimple models were used to determine exposure to sitecontaminants through indirect exposure routes, such as eatingcontaminated vegetation. The potential for effects to occur wasevaluated by comparing benchmark criteria, such as acceptabledaily intakes to estimated exposures. This comparison resultedin the calculation of hazard quotients. In general, a hazardquotient greater than 1 indicated a potential for impacts tooccur as a result of exposure to a particular chemical.

Potential ecological risks were evaluated for two mammalianspecies and three avian species. The potential for adverseecological effects on aquatic fauna of the Rocky Branch Creekwere also estimated. The results of the ecological riskassessment showed that each of the organisms evaluated had ahazard index exceeding the benchmark of 1. The total hazardindices for the ecological receptors evaluated ranged between 3 . 4and 54.

In addition to the Ecological Risk Assessment, fish tissuedata collected for TCDD from the Rocky Branch Creek/Bayou Metowatershed areas near the site suggests that contaminants ofconcern may pose an actual threat to local ecological receptors.EPA issued a ROD in September 1990 addressing the Vertac off-siteareas. One of the ROD requirements was to monitor fish in thestreams for dioxin and continue the ban on commercial fishing andthe advisory discouraged sport fishing as long as fish tissuedioxin levels are above Food and Drug Administration (FDA) alertlevels. FDA issued a health advisory stating that fish with2 , 3 , 7, 8-TCDD .>. 50 parts per trillion (ppt) should not beconsumed, and levels below 25 ppt pose no serious health threat.Based on this guidance, the Arkansas Department of Health (ADH)has established an advisory level of 25 ppt in fish flesh. Thecurrent advisory encompasses Bayou Meto from Arkansas Highway 13,upstream to the mouth of the discharge from Jacksonville WestWaste Water Treatment ponds, including Rocky Branch Creek andLake Dupree.

Based on 1994 fish tissue sampling results, dioxin71

concentrations appeared to generally decrease with increasing y^distance from the site. The highest dioxin concentrations were ^found in big mouth buffalo from Rocky Branch Creek and Bayou Meto f—upstream of Hwy 67-167. The concentrations found were 73 ppt and <?^94 ppt as TCDD TEQs, respectively. Concentrations of TCDD for owhite crappie at the Rocky Branch Creek location was 26 ppt, and c -19 ppt for large mouth bass at the Bayou Meto 67-167 location.At the Arkansas Highway 161 location, TCDD concentrations rangedfrom 22 to 36 ppt depending upon the species of fish sampled.

In comparison, as a part of EPA's National BioaccumulationStudy (EPA, 1 9 9 2 ) , fish data were collected to help identifybackground levels of dioxin in fish. Sixty fish samples werecollected from fresh and estuarine waters at a total of 34 sitesaway from points of obvious industrial activity. The average TEQwas 1 . 2 ppt (assuming half the detection limit for non-detects).When looking at all areas (not just pristine or background) EPA( 1 9 9 2 ) found an average of 11 ppt TEQ for 314 stations sampled.6 . 5 REMEDIAL ACTION GOALS

A Remedial Action Goal (RG) is a chemical-specificconcentration for each chemical of concern that helps determinewhether a contaminated media may be left in place or must beaddressed in the site remediation effort. Media exhibitingcontaminant concentrations below the Rgs may be left in placewithout treatment. Those wastes that exceed the RGs at the sitewill be addressed to meet requirements set out in the performancestandards for each media.

Two different risk assessment approaches were conducted forVertac soils in order to realistically evaluate appropriateRemediation Goals (RGs) for site contaminants based on givenlanduse and exposure assumptions. The first method. ReasonableMaximum Exposure ( R M E ) , is based on EPA risk assessment guidance(see Risk Assessment Guidance for Superfund: Volume I: HumanHealth Evaluation Manual (Part A) (Interim Final, EPA/540/1-89/002, December 1 9 8 9 ) / and the second method was based on MonteCarlo probabilistic risk modeling. Soil cleanup levels derivedfrom these two risk assessment methodologies can differ for anygiven exposure scenario. Assumptions that go into the models todevelop cleanup standards include; how often a person visits asite, how long the person stays there during each visit, how muchsoil or dust a person is exposed to at the site, how contaminatedthe soil is, how hazardous the contamination in the soil is, etc.One of the principle differences between the two risk assessmentmethodologies is that RME uses one combination of values for eachof these input assumptions (which is high but reasonablypossible), and Monte Carlo uses a wide range of values for eachinput parameter.

Over the past year, EPA has met on numerous occasions with72

various local civic groups and community leaders to discusscleanup activities at the Vertac site. One common element from ^'those discussions included, the potential for future commercial *redevelopment of the site, or portions of the site. With that in tmind, EPA has developed soil cleanup goals for dioxin at the ^Vertac Site that would be protective for a worker in acommercial/industrial setting. EPA acknowledges that certainportions of the site will be unavailable for potential futureredevelopment, i . e . , areas that house landfills, and areas thatwill require future ground water treatment. However, input fromthe community stressed that the workers required to maintainthese restricted portions of the site should also be protected toa commercial/industrial level and not be required to wear"moonsuits" to conduct their activities in the community.

The two principal contaminants in Vertac soils that willrequire remediation are, dioxins and furans as 2,3,7,8-TCDDtoxicity equivalents (TEQs), and tetrachlorobenzene ( T C B ) . TCDDcontamination is present across a wide area of the site and wasan unwanted byproduct from the production of the herbicide2 , 4 , 5 - T . TCB contamination, however, is only found in alocalized area or "hot spot", and is the result of a railroadtank car spill. RGs were not developed for other contaminants ofconcern at the site because they will be well below health basedaction levels after dioxin remediation takes place.

Following is a summary of EPAs risk evaluation used to setsite remediation goals for dioxin and furans (TEQ) at Vertac.

EPA evaluated a 50 ppb, 20 ppb, and a 5 ppb as not-to-exceedcleanup values for TCDD (TEQ) at the Vertac site using both RMEand Monte Carlo risk analysis. Some of the assumptions used inthe modelling included; a worker scenario, non-detects werecounted as 0.15 ppb (1/2 the detection limit), and that allremediated grids would be replaced with clean fill. Table 23presents all the parameters and values used in the RMEcalculations, and Table 24 presents the parameters and valuesused in the Monte Carlo calculations. A RME and Monte Carlosimulation was run for each of the soil cleanup levels and theresults of those analyses are shown in Table 25.

The RME results show that the excess lifetime cancer riskassociated with an average exposure point concentration of 50,20, and 5 ppb, are 7 . 6 x 10' 3, 3 . 0 x 10-3, and 7 . 6 x 10'4.Compared to RME risks, the Monte Carlo simulation risks were 3 . 1x 10-3, 1.2 x 10-3, and 3 . 1 x 10-4 using the 95% probabilitydistribution point when Monte Carlo analysis are run with thefixed point concentrations of 50, 20, and 5 ppb, respectively.

In order to more realistically evaluate the exposureconcentration of a person at the site, grid averaging wasemployed to determine the actual exposure concentration, rather

73

Parameters and Values Used in the RME Risk Calculations Assuming aHypothetical Worker Scenario Exposed Through Oral and Dermal Routes to SoilContaminated wi-th 2,3,7,8-TCDD TEQS at Vertac, Inc. Superfund Site.

ParameterConcentration (C.)

Conversion Factor (CF)

Skin Sui ace Area Availablefor Contact (SA.)Soil to Skin Adherence Rate (AF)

Dermal Absorption (ABS,?

Exposure Duration (ED)Exposure Frequency (EF)

Soil Ingestion rate (IR)

Oral Absorption (ABS,)Fraction Soil Contaminated (FI)

Body Weight (BW)Averaging Time (AT)Dermal Slope Factor (SF,,)

Oral Slope Fac-tor (SFJ

Units

mg/kg

kg/mg

cm2

mg/cm'-dayUnitlessyears

days/year

mg/dayUnitless

Unitless

kg

days

/mg/kg/day

/mg/kg/day

Value

0.005

1E-06

5000

1

0.03

25

250

50

0.2

0.5

70

25550

284000

156000

SourceSoil Cleanup level

US EPA, 19891

US EPA, 19922

US EPA, 1992

US EPA, 1992

US EPA, 19913

US EPA, 1991

US EPA, 1991

US EPA, 1992

US EPA, 1989

US EPA, 199 la4

US EPA, 199 la

US EPA, 1992

US EPA, 1994s

Risk was calculated by the following equations, adapted from EPA guidances0 •2•3•4)

Risk » ( C, * CF * SA * AF * ABS. * EF * ED * SF,, )BW * AT

+ ( C, * CF * IR * FI * ABS, * EF * ED * SF, )BW * AT

Paraietara and Values used in Monte CaricHypothetical Worker Scenario Exposed Through OralTC5D TEQs at Vertac, Inc. Superfund Site.

Parameter

2,3,7,8,-TCDDTEQsAdult SkinSurface Area

Fraction ofSkin ExposedAdherenceFactor

DenalAbsorption

ExposureFrequencyExposureDurationAdult BodyWeight

AveragingTineOralAbsorptionIngestion

Units

nfl/g(PDb?c>2

Unitless

•g/c«2-day

Unitless

days/yearYears

kg

days

Unit less

•g/day

RNE

5.0

20000

0.25

1.0

0.03

250

25

70

25550

0.2

50

Monte CarloAverage

0.674

18149

0.249

0.64

0.0155

250

7.88

71.9

25550

0.176

50

o Simulations arand Denial Rou1

Monte Carlo95th le

2.1

1B194

0.329

1.2

0.0286

250

34.4

88.5

25550

0.287

50

nd RME Risk Calctes to Soil Con1

DistributionTypeLognornal

LognorHal

Uniforn

Triangular

Unifom

Fixed PointEstinateemulative

Lognornal

Fixed PointEstimateUniforn

Fixed PointEstinate

eulations Assuiltaiinated with !

DistributionparametersM - 0.674SO - 0.8739Males

M • 19400SD - 37.4

FoalesM « 169008D - 37.4

Min. 0.161Max. 0.338Min. 0.2Best 0.2Max. 1 .5

Min. « 0.001Max. = 0.03

Min. = 0Max. = 48MalesQM -In 76.71QSO - lnl.19FeBalesGM «ln 64.72QSD -lnl.22

Min. = 0.05Max. = 0.3

Lng a>,3,7.8-

Source

SitedataUSEPA,1992

USEPA,1992USEPA,1992

USEPA,1992

USEPA,1991HERCULES1994Smith,1994

USEPA,1991HERCULES1994USEPA,1991

F02756

Parameters and Values UsedHypothetical Worker Scenario ExposedTCDD TEQs at Vertac, Inc. Superfund

Parameter

Fraction SoilContaninatedOral Risk

Demal Risk

Total Risk

Units

Unitless

Unitless

Unitless

Unitless

RME

0.5

1.4E-05

7.4E-04

7.5E-04

in Monte CarloThrough OralSite. (Contd.)

Monte CarloAverage0.5

1.0E-06

1.0E-05

1.0E-05

Simulations anand Denial Rout

Monte Carlo95th %le0.5

4.1E-06

4.1E-05

4.1E-05

d RME Risk Calces to Soil Cont

OistributionTypeFixed PointEstinate

ulations AssuDiaBinated with 2

Distributionparaneters

ng a, 5 , 7 , 8 -

Source

USEPA,1989

Comparison of Fixed-Point (BME) and Monte Carlo Risk Estimates - WorkerScenario Exposure Pathways Considered - Oral Ingestion Plus Dermal Contact with Soil.*Type of RiskEstimateFixed Point RME

Fixed Point RMEUsing 95% UCL on theArithmetic mean ofresidual grids.Monte CarloLognornalDistribution ofResidual Grids

AverageMaximumMinimum

percentiAes25 «50 %75 %90 %95 %

Lifetime Cancer RiskSoil 50 ppb RemovedCleanup - 50 ppb

7.6E-03Cleanup = 2 . 9 2 ppb

4.4E-04

Ave -3.210, SD-6.840Monte Carlo Ave"3.12Monte Carlo 95%»11.1

4.5E-053.9E-035.1E-09

3.1E-06l.OE-053.3E-059.6E-51.8E-043.9E-03

Lifetime Cancer RiskSoil 20 ppb RemovedCleanup =20 ppb

3.0E-03Cleanup = 1.8 ppb

2.7E-04

Ave=1.933, SD» 3.610Monte Carlo Ave«1.90Monte Carlo 95%«6.6

2.7E-053.8E-038.5E-09

2.0E-066.5E-062.0E-056.1E-051.1E-043.8E-03

Lifetime Cancer RiskSoil 5 ppb RemovedCleanup * 5 ppb

7.6E-04Cleanup = 0.675 ppb

l.OE-04

Ave-0.674, SD=0.8739Monte CarloAve-E0.674Monte Carlo 95%'=2.l

l.OE-051.3E-034.7E-09

9.3E-072.8E-068.4E-062 3E-054.1E-051.3E-04

C02758

OSthan defaulting to the cleanup goal as the exposure point &0concentration. In order to accomplish this, EPA next ran both r»»the RME and Monte Carlo simulations on the arithmetic mean (using C<1the 95% upper confidence limit - UCL95) of dioxin that would be CDpresent at the site after remediation. For not-to-exceed cleanup C-values of 50, 20, and 5 ppb, arithmetic mean values of 2 . 9 2 , 1 . 8 'and 0 . 6 7 6 ppb were obtained. The RME excess cancer risks 'associated with 2 . 9 2 , 1 . 8 , and 0.675 ppb were 4.4 x 10' 4, 2 . 7 x10'4 and 1 . 0 x l0'4 respectively.

For the Monte Carlo analysis, the lognormal distribution ofthese residual grids were used as the concentration term, and theexcess lifetime cancer risk at the 95% probability distributionwere 1.8 x 10' 4, 1.1 x 10' 4, and 4.1 x 10'5 for not to exceedvalues of 50, 20, and 5 ppb.

Table 26 depicts the RGs developed for the Vertac site.Different RGs are used for the area of the site that will remainbehind a fence where access will be restricted to site workersrequired to conduct site maintenance activities. A moreconservative RG was established for dioxin in areas that will beavailable for commercial/industrial redevelopment. The RG of1 ppb dioxin (TEQ) is based both on information from EPAs riskassessment and input from the community.Table 26. Remediation Goals for Contaminated Soil Media.

CONTAMINANT REMEDIATION GOALInside Fence (Restricted)Dioxins & Furans (TEQ)TetrachlorobenzeneOutside Fence (Unrestricted)Dioxins & Furans (TEQ)

5 ppb500 ppm

1 ppb

Information from EPA's site specific risk assessment showedthat a RG of 5 ppb TEQ for dioxin was necessary to be protectivefor a worker exposure scenario. The risk associated with a not-to-exceed soil cleanup'value of 5 ppb dioxin ranged from between1X10-4 to 4X10"5.

A second soil RG was also established for tetrachlorobenzene( T C B ) , associated with a spill area at the site. All crystallineTCB, and TCB in site soils greater than 500 ppm would beexcavated and treated off-site.

78

7 . 0 DESCRIPTION OF ALTERNATIVES °

7 . 1 ALTERNATIVES

Alternatives for remediation were developed in the FS by Q^,assessing technologies and the range of media to which they wouldbe applied. The FS considered separate "stand alone"alternatives for the two media addressed by Operable Unit 2 , theyare:• Soils - including both surface and subsurface soils.• Underground Structures - including underground utilities,

foundations, curbs, pads, and fuel storage tanks.SOILS

Following is a summary of the soils alternatives presentedin the FS. A more detailed description of the alternatives canbe found in the OU2 FS report itself.

The alternatives evaluated in the FS differed from oneanother principally in two ways; first by the cleanup levelpresented for TCDD in soils ( i . e . , the level of TCDD that wouldbe left on the ground after remediation to be protective for aspecific future site u s e ) , and secondly; by the concentration ofTCDD in soils that would be subjected to various treatment,containment, and/or capping options.

Three series of action levels for TCDD in site soils werepresented in the FS for many of the alternatives evaluated.These action levels were presented by the PRP in the FS as aguide for costing purposes only. The cleanup levels for thesite, however, were established by EPA after evaluating the riskassessment.

Table 27 presents a summary of the soils alternativesevaluated for this ROD, and Table 28 presents a summary of thequantities of materials addressed by the various treatmentoptions.

The disposition of the containerized soils from OperableUnit 1 (bagged soils, sludges from sewage treatment plant), andsoils that will be excavated from Rocky Branch Creek as a part ofthe Offsite Operable Unit were also evaluated in the OperableUnit 2 FS, because they are essentially the same media as OU2soils. In developing the alternatives, however, specialprovisions were included for both the Offsite soils and GUI soilsand sludges, because they are being consolidated onto the sitefrom a contiguous area of off-site contamination. Because thesesoils were excavated on an interim basis during the remediationof the off-site areas, they were evaluated as a

79

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28

COseparate item, and were evaluated using different action level ^criteria, despite the fact that they are the same media. The ^"decision to use different action levels in evaluating the ^disposition of Offsite and OU1 soils will eliminate the potentialthat these soils will be put back on the site without reducingtheir toxicity, mobility, or volume, regardless of the actionlevel chosen for the other onsite soils in OU2. The FS evaluatedconsolidation and containment into the onsite subtitle-C landfillas the only alternative for Offsite and OU1 soil media.

0<—

Alternative 1 No ActionDESCRIPTION

The no action alternative for OU2 media at the site providesa basis for comparing existing site conditions with thoseresulting from implementation of the other proposed alternatives.Under the no action alternative, no additional measures would beused to remediate contaminant sources. Access to the site wouldbe prohibited only by the existing site fence. Therefore, publicaccess would only be passively restricted. No institutionalcontrols, facility maintenance, or monitoring would beimplemented, except for those being performed in accordance withthe 1984 Consent Order.

Implementing no remedial activities for the OU2 media at thesite allows the existing contaminant sources to remain in place.The potential for exposure to contaminants is not reduced in thisalternative.

The Superfund program requires that a no action alternativebe considered at every site as a basis of comparison whenevaluating other alternatives. This alternative would notdecrease the toxicity. mobility, or volume of contaminants orreduce public health or environmental risks to acceptable levels.Also, this alternative would not comply with State and Federalenvironmental regulations, and therefore, is not favored by EPA.COST AND TIME OF IMPLEMENTATION

Capital Cost: $0Operation and Maintenance: $0Total Cost: $0Time of Implementation: 0 years

Alternative S-2 Containment and ConsolidationDESCRIPTION

Under this alternative, no action would be applied tosurface soils with a TCDD concentration of 50 ppb or less.

82

«Surface soils exceeding the action level of 50 ppb but less than <0500 ppb TCDD would be covered with a 12 inch thick layer of clean 2soil to prevent direct exposure and to reduce the potential for ^surface migration of contaminated soil (see Figure 11 ) . ^

The 10-fold range in the action level addressed by the soilcover is based on the assumption that if the soil is disturbed bysite workers that the contaminated soil would be diluted by 10 to1 dilution with the clean soil before exposure to workers occurs.The 10 to 1 dilution would yield an exposure concentration andtherefore an equivalent risk of exposure to below the actionlevel. This approach is consistent with that applied by U . S . EPAfor dioxin contaminated soils at other CERCLA sites in Region 6 .This approach was used in EPAs Record of Decision for both theJacksonville and Rogers Road Municipal Landfill sites. Inaddition, a 10-fold increase in the dioxin level for soils belowa depth of 1 foot was also used by EPA for the Missouri dioxinsites.

Surface soils to a depth of one foot below ground surfaceexceeding 500 ppb TCDD and bagged soils from OU1, would beconsolidated (landfilled) onsite. Excavated areas would bebackfilled to grade using clean soil and revegitated. Theexcavated materials would be placed into theconsolidation/containment unit (CCU) which was included as partof the selected remedy for certain OU1 materials. The CCUpresented in the OU2 FS would be a modification or enlargement ofthe CCU to be constructed for OU1 materials. Modifications tothe CCU would incorporate design standards equivalent to thoserequired by RCRA (Subtitle C) hazardous waste landfill (seeFigure 1 2 ) .

Except for the TCB spill area, subsurface soils greater than1 foot below the ground surface would remain in place becausethere are no direct exposure pathways to subsurface soils. Anindirect exposure pathway is present through the potentialmigration of site compounds from these soils into ground water,however, site related compounds, especially TCDD bind tightly tothe soils and are not considered very mobile.

The crystalline TCB and associated soils exceeding theaction level of 500 ppm will be excavated and transported off-site for incineration at a RCRA permitted facility. Thetreatment residuals from the TCB and related soils would bedisposed of by the off-site facility that performs the treatment.

Administrative and engineering control of site access wouldbe implemented. Administrative controls would include deednotifications to limit future land use for the portion of theproperty that will remain fenced. Engineering controls wouldinclude maintenance of; the site fence, engineered structuresproposed under this alternative ( i . e . , the CCU), and the soil and

83

Vegetation.^- .—^- -^- —„———, r , , „——J^-. -^

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94P-4327 7/28/94 Not tO Scale

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12" Sand forLateral Drainage

GroundSurface

94P-1307 3/4/94

DOUBLE-LINED CONSOLIDATION/CONTAINMENT UNIT - CONCEPTUAL CROSS-SrfcflA? 6 6

vegetative cover over areas that were capped. Monitoring and »„»maintenance of the site would also be performed. ^r-Alternative S-2 reduces potential exposure to target ^compounds at the site through offsite treatment of TCB (Qcontamination and consolidation or containment of TCDD <contaminated soils. Under this alternative approximately 83percent of the TCDD contaminated soil will be covered or iisolated.COST AND TIME OF IMPLEMENTATION

Capital Cost: $5,896,000$37,700

$6,500,000 (rounded)2 years

Operation and Maintenance:Total Cost:Time of Implementation:

Alternative S-2, Option ADESCRIPTION

Option A provides the same remedial action actions for theOU2 soils as Alternative S-2 except with different action levelsfor TCDD. Bagged OU1 soils and crystalline TCB and spill relatedsoils would be the same as that described for Alternative S-2.For Alternative S-2A, surface soils with TCDD concentrationsabove 20 ppb would be addressed by remedial action. Thosesurface soils greater than 200 ppb would be excavated and placedin the onsite CCU, and those soils with concentrations greaterthan 20 ppb, but less than or equal to 200 ppb, would be coveredin place.COST AND TIME OF IMPLEMENTATION

Capital Cost:Operation and Maintenance:Total Cost:

$6,39 8 , 0 0 0$37,700

$7,000,000 (rounded)Time of Implementation: 2 years

Alternative S-3 Containment, Consolidation and OnsiteDesorption and Chemical Treatment

DESCRIPTIONThis alternative is the same as S-2, with the following key

differences. Surface soils with concentrations of TCDD exceeding2,000 ppb will be treated onsite. Two options to thisalternative are evaluated. Alternative S-3A, and S-3B, which usethe same remedial approach but are based on different actionlevels. Treating soils with concentrations greater of TCDD

86

00greater than 2,000 ppb, will permanently reduce toxicity, <aomobility, and volume of a large portion of the TCDD. The I"-treatment process will consist of thermal desorption of the soils C'1to extract the organic compounds, including TCDD. The organic 0compounds will exit the treatment process as a condensate which Cwill be treated by chemical dechlorination. Chemical 'dechlorinate residuals will be incinerated. The treated soilresiduals are considered to be clean, however, they will be usedin the CCU as fill, or they will be delisted and used on the sitefor grading purposes.

Soils associated with the TCB spill would be desorbedonsite, with the desorption residuals incinerated off-site.Crystalline TCB would be sent off-site for treatment at apermitted facility.COST AND TIME OF IMPLEMENTATION

Capital Cost: $8,546,000Operation and Maintenance: $37,700Total Cost: $9,100,000 (rounded)Time of Implementation: 3 years

Alternative S-3, Option ADESCRIPTION

Alternative S-3A would address surface soils with TCDDconcentrations greater than 20 ppb. Surface soils with TCDDconcentrations greater than 1,000 ppb would be subjected toonsite thermal desorption. Soils with TCDD concentrationsgreater than 200 ppb and less than or equal to 1,000 ppb would beexcavated and consolidated in the onsite CCU. Surface soils withTCDD concentrations greater than 20 ppb but less than or equal to200 ppb would be left in place and covered with a one foot thicksoil cover. Other media such as the OU1 bagged soils,crystalline TCB, and spill related soils would be treated thesame as Alternative S-3.COST AND TIME OF IMPLEMENTATION

Capital Cost:Operation and Maintenance:Total Cost:Time of Implementation:

$ 9 , 3 9 6 , 0 0 0$37,700$10,000,000 (rounded)3 years

87

Alternative S-3, Option BDESCRIPTION

Alternative S-3B provides for onsite thermal desorption of 0surface soils with TCDD concentrations in excess of 2,000 ppb, •consolidation in the onsite CCU of surface soils with TCDDconcentrations between 350 ppb and 2,000 ppb, and covering ofsurface soils with TCDD concentrations greater than 35 ppb.Other media such as the OU1 bagged soils, crystalline TCB, andspill related soils would be treated the same as Alternative S-3.COST AND TIME OF IMPLEMENTATION

Capital Cost: $8,687,000Operation and Maintenance: $37,700Total Cost: $9,300,000 (rounded)Time of Implementation: 3 years

Alternative S-4 Containment, Consolidation and OnsiteIncineration

DESCRIPTIONThe actions described under Alternative S-3 would be

implemented under this alternative except that onsiteincineration would be used in place of thermal desorption anddechlorination for surface soils with TCDD concentrationsexceeding 2,000 ppb. One option to this alternative. AlternativeS-4A, was also evaluated. The soils associated with the TCBspill exceeding 500 ppm and the crystalline TCB would betransported to an off-site incineration facility for treatmentbecause of their non-F listing. Residuals resulting from onsiteincineration would be consolidated with other OU2 media in theecu.COST AND TIME OF IMPLEMENTATION

Capital Cost: $8,900,000Operation and Maintenance: $37,700Total Cost: $9,500.000 (rounded)Time of Implementation: 3 years

Alternative S-4, Option ADESCRIPTION

Surface soils with TCDD concentrations in excess of 1,000ppb would be treated by an off-site incinerator. Surface soilswith TCDD concentrations greater than 200 ppb but less than or

88

equal to 1,000 ppb would be placed into the onsite CCU. Soils 0exceeding 20 ppb TCDD but less than or equal to 200 ppb would be I>covered in place. t'*GSlCOST AND TIME OF IMPLEMENTATION 0<—>

Capital Cost: $10,959,000Operation and Maintenance: $37,700Total Cost: $11,500,000 (rounded)

Time of Implementation: 3 yearsAlternative S-5 Onsite Desorption with Off-site IncinerationDESCRIPTION

Under this alternative, surface soils with TCDDconcentrations above 50 ppb and soils associated with the TCBspill would be excavated and treated onsite by thermaldesorption. One option to this alternative. Alternative S-5A,was also evaluated. The condensate from the thermal desorptionprocess would be transported off-site for incineration at a RCRApermitted facility. The treatment residues would be disposed ofby the treatment facility. The soils from OU1 would be placedinto the onsite CCU.COST AND TIME OF IMPLEMENTATION

Capital Cost:Operation and Maintenance:Total Cost:

$14,603,000$10,400

$14,800,000 (rounded)Time of Implementation: 4 years

Alternative S-5, Option ADESCRIPTION

Alternative S-5A, provides for the same excavation, onsitetreatment, and off-site incineration for the surface soils asAlternative S-5, except that a lower action level of 20 ppb forTCDD applies. Bagged soils from OU1, and TCB spill soils wouldalso be treated using the onsite thermal desorption process.COST AND TIME OF IMPLEMENTATION

Capital Cost:Operation and Maintenance:Total Cost:Time of Implementation:

89

$26,6 3 6 , 0 0 0$10,400

$26,800,000 (rounded)4 years

Alternative S-6 Off-site Incineration 'T^!>

DESCRIPTION 2>010c—Under this alternative, surface soils with TCDD

concentrations above 50 ppb. crystalline TCB, and the soilsassociated with the TCB spill exceeding 500 ppm would beexcavated and incinerated off-site at a RCRA permitted facility.One option to this alternative. Alternative S-6A, was alsoevaluated. Treatment residues from off-site incineration wouldbe disposed of by the off-site treatment facility. The baggedsoils from OU1 would be consolidated into the onsite CCU.COST AND TIME OF IMPLEMENTATION

Capital Cost: $62,089,000Operation and Maintenance: $10,400Total Cost: $62,200,000 (rounded)Time of Implementation: 5 years

Alternative S-6, Option ADESCRIPTION

Alternative S-6A, provides for the same excavation and off-site incineration for the surface soils, but applies to a loweraction level of 20 ppb TCDD.COST AMD TIME OF IMPLEMENTATION

Capital Cost: $164.601,000Operation and Maintenance: $10,400Total Cost: $164,800,000 (rounded)Time of Implementation: 5 years

Alternative S-7 Containment (Capping)DESCRIPTION

Under this alternative, no action would be applied tosurface soils with a TCDD concentration of 50 ppb or less. Thesurface soils exceeding the action level of 50 ppb TCDD would becovered with a 12 inch layer of clean soil to prevent directexposure and reduce the potential for migration of surface soilsdue to rainfall, wind, etc. An option to this alternative, S-7A,would use the same remedial approach but with different TCDDaction levels was also evaluated.

The crystalline TCB and associated TCB spill related soilsexceeding the action level of 500 ppm would be excavated and

90

transported off-site for incineration at a RCRA permitted <facility. Following treatment of the TCB and associated soils, ^the residuals would be disposed of by the off-site treatment j^facility. <?>l

0Administrative and engineering control of site access as c,described in Alternative S-2 would also be implemented. >COST AMD TIME OF IMPLEMENTATION

Capital Cost:Operation and Maintenance:Total Cost:

$5,698,000$37,700

$6,300,000 (rounded)Time of Implementation: 2 years

Alternative S-7, Option ADESCRIPTION

Alternative S-7A, provides for the same remedial actions asAlternative S-7, except with different action levels for TCDD.Surface soils with TCDD concentrations above 20 ppb would beaddressed by the remedial action. Bagged soils from OUl, andcrystalline TCB and TCB spill related soils would be the same asthe remedial action described in Alternative S-7.COST AND TIME OF IMPLEMENTATION

Capital Cost:Operation and Maintenance:Total Cost:

$6,076,000$37,700

$6,700,000 (rounded)Time of Implementation: 2 years

Alternative S-8 Consolidation (Landfilling)DESCRIPTION

Under this alternative, no action would be applied tosurface soils with a TCDD concentration of 50 ppb or less. Thesurface soils exceeding the action level of 50 ppb TCDD would beexcavated to a depth of 1 foot and consolidated onsite in theCCU. As an option to this alternative. Alternative S-8A, woulduse the same remedial approach, but with different TCDD actionlevels.

The crystalline TCB and associated TCB spill related soilsexceeding the action level of 500 ppm would be excavated andtransported off-site for incineration at a RCRA permittedfacility. Following treatment of the TCB and associated soils,the residuals would be disposed of by the off-site treatment

91

facility.COST AND TIME OF IMPLEMENTATION

Capital Cost: $6,720,000$19,500

$7,000,000 (rounded)2 years

Operation and Maintenance:Total Cost:Time of Implementation:

Alternative S-8, Option ADESCRIPTION

Alternative S-8A, provides for the same remedial actions forthe OU2 surface soils as S-8, except with different action levelsfor TCDD. Bagged soils from OU1, and crystalline TCB and TCBspill related soils would be the same as that described forAlternative S-8. Surface soils with TCDD concentrations above 20ppb would be excavated and placed into the onsite CCU.COST AND TIME OF IMPLEMENTATION

Capital Cost:Operation and Maintenance:Total Cost:

$8,220,000$19,500

$8,500,000 (rounded)Time of Implementation: 2 years

UNDERGROUND UTILITIES

Following is a summary of the underground utilitiesalternatives presented in the FS. A more detailed description ofthe alternatives can be found in the OU2 FS report itself.

Table 29 presents a summary of the underground utilitiesalternatives.Alternative U-l No ActionDESCRIPTION

The no action alternative for underground structures wouldinvolve no additional measures. The underground utilities andfuel storage tanks would remain buried with their contents inplace. Access to the site would be prohibited by the existingsite fence, therefore, public access would be passivelyrestricted. Specific institutional controls, maintenance, ormonitoring would not be implemented, except for those that wouldbe performed in accordance with the monitoring and maintenanceplan in the 1984 Court Order.

92

Table 29SUMMARY OF THE UNDERGROUND UTILITIES ALTERNATIVES

Alt

U-l

U-2

U-3

No Action

All undergrounditnicturel

Aqueous Flush

Chemical sewer

Chemical »ewcr

Concrete/SandPlug

Undergrounditorage tanks

Chemical tewer,Undergrounditorage tanks

Hydroblast/Scarification

Foundationsand curbs

Foundation*and curbs

Surface Seal

Foundationsand curb* withpersistent (tains

Aqueous PhaseTreatment1

Rinse materialsfrom flush,hydroblaA

Rjuse inaterialsfroa flush,hydroblast

Solid PhaseTreatment1

Recovered solid*bom Bush,

icarificadoo, and/orhydroblaft

Recovered solidsfrom fiusb,

scarification, and/or hydroblast

NOTCS: 1 Aqueous phase treatment at oolite treatment plant.2 Solid phase treatment will be selected with soils alternative.

f02774

t0Implementing no remedial activities for the OU2 media at the site allows the existing contaminant sources to remain in place. j »The potential for exposure to contaminants is not reduced in this alternative. Q

The Superfund program requires that a no action alternativebe considered at every site as a basis of comparison whenevaluating other alternatives. This alternative would notdecrease the toxicity, mobility, or volume of contaminants orreduce public health or environmental risks. Also, thisalternative would not comply with State and Federal environmentalregulations, and therefore, is not be favored by EPA.COST AND TIME OF IMPLEMENTATION

Capital Cost:Operation and Maintenance:Total Cost:

$0$0$0

Time of Implementation: 0 yearsAlternative U-2 Equipment Plugging and CleaningDESCRIPTION

Under this alternative, corrective measures would beimplemented to reduce the risk associated with the undergroundstructures. The chemical sewer would by hydraulically flushed toremove solids from the line. After flushing, the access to thesewer would be restricted by installing plugs at all availableaccess locations. In conjunction with line plugging, subsurfacecut-off barriers would be installed across the line and beddingcross-section. These cut-off barriers would be constructed ofmaterials such as clay, membrane sheeting, or other lowpermeability material. The purpose of these barriers is torestrict potential preferential contamins.nt migration pathways.They would be located in the field at points where plugging isconducted or where migration may occur off-site. Any excesscontaminated soil from the excavation process would be handled inaccordance with the soil alternative.

The contents of the underground storage tanks (USTs) wouldbe removed and incinerated either onsite or off-site. Wherepossible, the fuel materials from the USTs may be recycled. Thefoundations and curbs would be cleaned by hydroblasting usinghigh pressure, low volume water. In areas with persistentstaining, surface scoring (such as scarification) will be used toremove visible contamination from the exposed foundations andcurbs. Water generated from the sewer flushing and concretehydroblasting would be treated in the onsite water treatmentplant. Solids generated from flushing, hydroblasting, andscarification would be handled in accordance with the selected

94

<0I>alternative for soils.^

COST AND TIME OF IMPLEMENTATION ff<(

Capital Cost: $1,229,000 c-Operation and Maintenance: $0 >Total Cost: $1,229,000 (rounded)Time of Implementation: 1.5 years

Alternative TJ-3 Equipment Plugging, Cleaning, and SealingDESCRIPTION

This alternative is similar to Alternative U-2, with thefollowing additions. After flushing, the sewer would be filledwith grout to improve the structural integrity of the line andprevent migration of contaminants through the pipe. In addition,a surface sealant would be applied to foundations and curbs inareas of persistent staining i . e . , visible staining that is notremoved by scarification.COST AND TIME OF IMPLEMENTATION

Capital Cost: $1,359,000Operation and Maintenance: $0Total Cost: $1,359,000 (rounded)Time of Implementation: 1.5 years

7.2 ARARS

The Superfund Amendments and Reauthorization Act (SARA) of1986 and the National Contingency Plan ( N C P ) , revised April 9 ,1990, provides that the development and evaluation of remedialactions under the Comprehensive Environmental Response,Compensation, and Liability Act of 1980 (CERCLA) must include acomparison of alternative site responses to applicable orrelevant and appropriate Federal and state environmental andpublic health requirements (ARARs).

Identification of ARARs must be done on a site-specificbasis. The NCP and SARA do not provide across-the-board standardsfor determining whether a particular remedial action will producean adequate remedy at a particular site. Rather, SARA and theNCP recognize that each site has unique characteristics that mustbe evaluated and compared to those applicable, or relevant andappropriate requirements that apply under the givencircumstances. In accordance with the requirements of the NCP,the remedial action selected must meet ARARs unless a waiver fromspecific requirements can be granted.

95

For remedial action performed under SARA, permits for j>.compliance with the Resource Conservation and Recovery Act t .(RCRA), National Pollution Discharge Elimination System (NPDES), £>and Clean Air Act (CAA) regulations for onsite remedial actions Mare not required. However, CERCLA and SARA do require that the 0selected remedy meet relevant and appropriate regulatory C-standards or performance levels where possible, even though apermit is not required. Relevant and appropriate regulatorystandards address problems or situations sufficiently similar tothose encountered at a CERCLA-regulated site. Therefore, theiruse is well-suited to the particular site of concern. ARARs aredefined as follows:• Applicable Requirements are those cleanup standards,

standards of control, and other substantive environmentalprotection requirements, criteria, or limitationspromulgated under federal environmental, stateenvironmental, or facility siting law, that specificallyaddress a hazardous substance, pollutant, contaminant,remedial action, location, or other circumstance found at aCERCLA site.

• Relevant and appropriate requirements are those cleanupstandards, standards of control, and other substantiveenvironmental protection requirements, criteria, orlimitations promulgated under federal or state law that,while not "applicable" to a hazardous substance, pollutant,contaminant, remedial action, location, or othercircumstance at a CERCLA site, address problems orsituations sufficiently similar to those encountered at aCERCLA site.

ARARs may be divided into the following categories:• Chemical-specific requirements are health or risk-based

concentration limits or ranges in various environmentalmedia for specific hazardous substances, pollutants, orcontaminants. These limits may take the form of actionlevels or discharge levels.

• Location-specific requirements are restrictions onactivities that are based on the characteristics of a siteor its immediate environment. An example would berestrictions on wetlands development.

• Action-specific requirements are controls or restrictions onparticular types of activities in related areas such ashazardous waste management or wastewater treatment. Anexample would be RCRA incineration standards.In addition to legally binding laws and regulations

addressed above, other federal and state environmental and public9 6

00health programs may also develop criteria, advisories, guidance, »and non-promulgated policy statements that are not legally j.,,binding, but are identified for appropriate consideration in Q^development and evaluation of remedial alternatives. These "To ^Be Considered" (TBC) programs are not potential ARARs but may be ^evaluated as appropriate along with ARARs.

The potential ARARs for OU2 media, are listed in Table 30.These potential ARARs were identified based on site-specificconditions and are described in more detail in the remainder ofthis section.

In identifying ARARs for OU2, it is important to recognizethat the Vertac site has three existing burial areas that areclosed under a 1984 Court Order; therefore this site in part,will likely remain a place where hazardous wastes are disposed.Table 30. Potential ARARs for the Vertac Site, Jacksonville,Arkansasfham-ical Specific• Resource Conservation and Recovery Act (RCRA)• Clean Water Act (CWA)• Safe Drinking Water Act (SDWA)• Clean Air Act (CAA)• Arkansas Water and Air Pollution Control Act• Arkansas Noncriteria Air Pollutants Control Strategy• Arkansas State Groundwater Quality Protection Strategy• State Implementation Plan for Air Pollution Control• Water Quality Standards for Surface Waters of the State ofArkansas

• State Administration of the National Pollutant DischargeElimination System

• Hazardous Waste Management (Arkansas)• Arkansas Air Pollution Control CodeLocation SpecificResource Conservation and Recovery Act (RCRA)Arkansas Solid Waste Management CodeState Administration of the National Pollutant DischargeElimination SystemHazardous Waste Management (Arkansas)Arkansas Air Pollution Control Code

Action Specific• Resource Conservation and Recovery Act (RCRA)• Clean Water Act (CWA)• Clean Air Act (CAA)• Arkansas Solid Waste Management Code

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05• Civil Penalties (Arkansas)• Administrative Procedures (Arkansas).^.^^^^^^ ^^^^^ . - i>

Fee System for Environmental Permits (Arkansas) "'• Fee for Landfill Disposal/Solid Waste Planning and Recycling "

Grant Program (Arkansas) -• Procedures of Submitting an Application for an Incinerator

Permit• State Implementation Plan for Air Pollution Control

7 . 2 . 1 Federal ARARsRecovery Act (RCRA)

The Resource Conservation and Recovery Act (RCRA) (42 USCA6901 et seq.) mandated U . S . EPA to:• Under Subtitle C, establish a comprehensive regulatory

program to control and manage hazardous waste.• Under Subtitle D, promulgate regulations containing

guidelines to assist in the development and implementationof state nonhazardous solid waste management plans.RCRA requirements may be ARARs because some materials at the

Vertac site may be considered RCRA hazardous wastes. In general,RCRA regulations apply to the management of RCRA hazardous wastesand RCRA waste management facilities. Regulations promulgatedunder RCRA generally provide the basis for management ofhazardous waste and establish technology-based requirements forhazardous waste facilities. RCRA facility design standards mayalso be consulted if considered relevant and appropriate forwastes other than RCRA hazardous wastes containing significantconcentrations of hazardous constituents.Chemical-Specific RequirementsHazardous Waste Identification

Hazardous waste identification under RCRA is detailed within40 CFR 261. The two basic classifications of RCRA hazardouswaste are:• Characteristic hazardous wastes (defined under Subpart C of

40 CFR 2 6 1 ) , which involve evaluation of the followinggeneral waste characteristics:

Ignitability (DOOl waste)Corrosivity (D002 waste)Reactivity (D003 waste)Toxicity (D004 - D043 wastes) due to specific chemicalspecific compounds

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Listed hazardous wastes (defined under Subpart D of 40 CFR2 6 1 ) , which involve specific identification of the followingregulatory listings:Hazardous Waste from Nonspecific Sourceslisted under 40 CFR 2 6 1 . 3 1 ) .Hazardous Waste from Specific Sources (Klisted under 40 CPR 2 6 1 . 3 2 ) .

(F - series wastes

series wastes

Commercial Chemical Productslisted under 40 CFR 2 6 1 . 3 3 ) .

(P - and U series wastes

Specific tests cited in the regulations are used todetermine if the solid waste is a RCRA characteristic hazardouswaste. The maximum concentrations of contaminants allowed in theleachate of a solid waste before the solid waste is consideredhazardous for the toxicity characteristic (TC) are presented in40 CFR 261.24. Site-related compounds for which a TC level hasbeen identified include:

Waste CodeD016D041D042D017

Compound Name TC Level2,4-Dichlorophenoxyacetic Acid 10.0 mg/L2.4.5-Trichlorophenol 400 mg/L2.4.6-Trichlorophenol 2 . 0 mg/LSilvex 1.0 mg/L

To determine if a solid waste is a listed RCRA hazardouswaste, it is necessary to examine the source of the waste. Atthe Vertac site, manufacture and formulation of insecticides andherbicides resulted in the generation of process wastescontaining chlorinated benzenes, chlorinated phenols,chlorophenoxy herbicides, and dioxin. These substances have beenfound in the environmental media (soils, groundwater, and surfacewater) at the site. A comprehensive listing of mechanisms thatreleased these substances into these environmental media isunavailable; however, materials handling practices, wastemanagement practices and material releases during the 45 years ofplant operation are the most probable cause. A number ofmechanisms could be hypothesized based on the types of activitiesperformed during site operation, but most of the releases cannotbe confirmed. An exception is the tetrachlorobenzene spill,which resulted from a known release while transferringtetrachlorobenzene from a rail car to a material storage tank.

Some of the production processes performed at the Vertacsite would have generated wastes given hazardous waste numbersF020, F022, F023, F026, or P027 (40 CFR §261.31, dioxin-relatedhazardous wastes from non-specific sources). These waste numbersare referred to in this document as "F-02X" wastes and aredefined in 40 CFR 2 6 1 . 3 1 .

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Some of the substances found in the site soils and other OU2 T-Imedia may have resulted from the release of wastes other than the 00F-02X wastes. These wastes could potentially be classified as !>•follows: ^• Listed hazardous wastes from specific sources as defined in c-

40 CFR §261.32; K042, K043, and K099 wastes are related to2,4-D and 2 , 4 , 5 - T production.

• Wastes defined in 40 CFR §261.33 as discarded commercialchemical products, off-specification species, containerresidues, and spill residues thereof. The hazardous wasteidentification code U240 (2 , 4 - D salts, and esters) may beapplicable to some of the OU2 media at the site.

• The soils containing residues from a rail car spillcontaining still bottoms from the production ofchlorobenzenes (called throughout this FS as the"tetrachlorobenzene spill soils") may be listed as a K085specific source listed hazardous waste. K085 listedhazardous wastes are identified in 40 CFR §261.32 asdistillation or fractionation column bottoms from theproduction of chlorobenzenes.Historically some chlorobenzene still bottoms were purchasedfrom an off-site facility (generated at the off-sitefacility during the production of dichlorobenzene) and weretransported via rail car to the site. The still bottomscontained high levels of tetrachlorobenzene and weredechlorinated onsite as part of the 2,4,5-trichlorophenolmanufacturing process. Prior to use onsite, a hose leadingfrom a rail car containing the still bottoms to a storagetank ruptured spilling the chlorobenzenes onto the groundsurface along the rail spur immediately north of the CPA.These soils are included as part of the OU2 remedial actionand may require management as a K085 waste.

• Residues from the treatment of a listed RCRA hazardous wasteare themselves considered RCRA hazardous wastes unlessdelisted. Residues resulting from the incineration orthermal treatment of the F-02X materials would be consideredF028 wastes (40 CPR § 3 6 1 . 3 1 ) .The regulations pertaining to the dioxin-containing F-listed

wastes are more stringent than for the other listed wastes. Forexample, 9 9 . 9 9 9 9 percent (six 9s) destruction removal efficiency(DRE) is required for incineration of these dioxin-containingwastes, while only 9 9 . 9 9 percent (four 9s) DRE is required formost other wastes. Regulatory requirements for the land disposalof the F-02X are also more stringent than for other wastes.Therefore, complying with the regulations applicable to the F-listed wastes ensures compliance with less stringent regulations

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applicable to non-F02X listed RCRA wastes. 0^00Mixture Rule/Contained-In Policy t1**(M

The "mixture rule", 40 CFR §2 6 1 . 3 , states that a mixture of ®a solid waste and a listed RCRA hazardous waste is considered a c—RCRA hazardous waste. This may be applicable to the solids in 'the underground piping if they are determined to be mixture of a 'solid waste and a listed RCRA hazardous waste. In the "containedin" policy, the U . S . EPA has further expanded the mixture rule toinclude environmental media (not considered a "solid waste" underRCRA) mixed with a listed RCRA hazardous waste. In this policy,U . S . EPA states that the mixture of a listed RCRA hazardous wasteand an environmental media shall be a listed RCRA hazardous wasteuntil decontaminated. As a result of this policy, onsite soilscontaining listed RCRA hazardous waste may be required to bemanaged as a listed RCRA hazardous waste.RCRA Maximum Contaminant Limits (MCLs)

As part of the groundwater protection requirements for RCRAtreatment, storage, or disposal facilities (TSDs), 40 CFR §264.94promulgates maximum concentrations of constituents in groundwater(RCRA MCLs). The constituents, and their associatedconcentrations in ground water, addressed by this requirement arepresented in 40 CFR §264.94. The standards for site-relatedcompounds are as follows:

• 2,4-D 0.1 mg/L• Silvex 0.01 mg/LThese groundwater protection standards are equal to MCLs

established under the National Primary Drinking Water Standards,based on the 1962 Public Health Service Regulations under theSafe Drinking Water Act (SDWA). The basic jurisdictionalprerequisites for RCRA MCLs are part of the RCRA groundwatermonitoring and response requirements, which apply to RCRAregulated units subject to permitting ( e . g . , landfills, surfaceimpoundments, waste piles, and land treatment units) thatreceived RCRA hazardous waste after July 2 6 , 1982, RCRA MCLswould be considered as part of any long-term monitoring programfor most onsite remedial measures. Consideration of long-termmonitoring of groundwater is most appropriate as part of OU3,which will focus on groundwater issues.RCRA Location-Specific Requirements

Location-specific ARARs within RCRA are location standardsdetailed under 40 CFR 264.18 that are potentially applicable tothe siting of a new onsite TSD unit managing RCRA hazardous wasteas part of a remedial alternative.

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These location standards are specified and addressed as COfollows: 00

!>• Seismic considerations restricting TSD facilities within 200 01

ft of a fault that has had a displacement within Holocene 0time. Because the Vertac site is not located in C—jurisdictions listed in Appendix VI of 40 CFR 264, such an 'onsite facility would be in compliance with this requirementas per 40 CFR 2 7 0 . 1 4 ( b ) ( 1 1 ) .

• Floodplain considerations requiring TSD facilities locatedwithin a 100-year floodplain to be designed, constructed,operated, and maintained to prevent washout (the movement ofhazardous waste from the active portion of the facility as aresult of flooding). The site contains portions of the 100-year floodplain. Approximately 150 feet to the east andwest of Rocky Branch Creek are included within the 100-yearfloodplain.

• Salt dome formations, salt bed formations, underground minesand caves are locations where placement of non-containerizedor bulk liquid hazardous waste is prohibited. Thisrequirement is not applicable to the Vertac site becausethese features are not located within the area of the site.

RCRA Action-Specific ARARsAction-specific ARARs are usually technology or activity-

based requirements or limitations on actions taken with respectto hazardous wastes. These requirements may be triggered by theparticular remedial action that is selected to accomplish theselected alternative. Because there is more than one alternativeaction for the OU2 media at the site, many different requirementsmay be applicable.General TSD Facility Requirements

General TSD facility requirements under RCRA apply to thosefacilities that treat, store, or dispose RCRA hazardous wastes.The requirements that could potentially be ARARs at the siteinclude:• General facility standards (Subpart B) including those for

waste analysis, security, inspections, and personneltraining.• Preparedness and prevention standards (Subpart C) addressing

facility design and operation, required equipment, testingand maintenance of required equipment, communication/alarmsystems, and aisle space for container storage.

• Contingency plan and emergency procedures (Subpart D ) .102

• Manifest system recordkeeping and reporting (Subpart E) to ^continuously track off-site hazardous waste transport. ou

• Releases from solid waste management units (Subpart F) for —new landfills, land treatment, and waste pile units. This °includes provision for groundwater monitoring programs. -"

• Closure and post-closure requirements (Subpart G) requiringremoval of waste and residuals to an extent that controls,minimizes, or eliminates post-closure release of hazardousconstituents.

• Use and management of containers (Subpart I) which providesstandards for the condition of containers, wastecompatibility, inspections, storage building design andconstruction, and closure.

• Landfills (Subpart N ) .• Incinerators (Subpart 0 ) .Land Disposal Restrictions

The land ban, promulgated under RCRA on 7 November 1986 (40CFR 2 6 8 . 3 1 ) , stipulates that no hazardous wastes (as defined in40 CFR 261.31) may be land disposed unless treated. RCRArequires that the treatment of wastes that are subject to the banon land disposal attain levels achievable by the bestdemonstrated available technology (BDAT). BDAT requires that atreated F-02X material have less than 1 ppb TCDD, as measured bythe TC test, prior to disposal in a RCRA-permitted landfill.

The land disposal restrictions also apply to the storage ofcertain hazardous wastes onsite. These restrictions prohibit theonsite storage of "banned" wastes for longer than 1 year unlessthe owner/operator can prove that the extended storage is solelyfor the purpose of accumulating enough waste for propertreatment.Consolidation

During the onsite consolidation activities, materials willbe consolidated within the "area of containment" ( A O C ) , andtherefore, the land disposal restrictions are not applicable( U . S . EPA, 1 9 8 9 ) . According to EPA guidance (OSWER Directive9347.3 05FS), " for the LDRs to be applicable to a CERCLAresponse, the action must constitute placement of a restrictedRCRA hazardous waste". Therefore, it must first be determinedwhether consolidation activities considered or contemplated atthe Vertac site constitute placement and if so, whether a RCRAhazardous waste is involved. As stated in the above mentionedOSWER Directive "to assist in defining when placement does and

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does not occur for CERCLA actions involving onsite disposal of -wastes, EPA uses the concept of areas of contamination (AOCs), ,y>which may be viewed as equivalent to RCRA units, for the purposes of LDR applicability determinations. An AOC is delineated by the areal extent of contiguous contamination. Such contamination Qmust be continuous, but may contain varying types and Qconcentrations of hazardous substances. Depending upon site , ,characteristics, one or more AOCs may be delineated" (OSWER , ,Directive 9347.305S). Placement does not occur when wastes areleft in place, or moved within an AOC. Specifically, "placementdoes not occur when the wastes are consolidated within the AOC".Additionally, minimum technology requirements (MTRs) are notapplicable within an AOC, but may be relevant and appropriate.

0

If the materials are treated onsite within the AOC andredeposited within the AOC such as in the consolidation unit,then placement has occurred and the land disposal restrictionsapply. Specifically the treated materials must meet 1 ppb TCDDas determined by TCLP. Land disposal restrictions have beenestablished for most of the hazardous wastes associated with theVertac site.Incinerators

Incineration of a RCRA hazardous waste is regulated under 40CFR 264 Subpart 0. These regulations include provisions for:• Waste feed analysis (40 CFR 2 6 4 . 3 4 1 ) .• Operating requirements (40 CFR 2 6 4 . 3 4 5 ) . This includes a

control of fugitive emissions either by keeping thecombustion zone totally sealed or maintaining a combustionzone pressure lower than atmospheric pressure. In addition,an automatic cutoff system must be provided to stop thewaste feed when operating conditions deviate from designconditions.

• Monitoring and inspections (40 CFR 2 6 4 . 3 4 7 ) . This includesmonitoring of the following operating parameters:- Combustion temperature.- Waste feed rate.- Combustion gas velocity.- Carbon monoxide (CO) emissions.

• Closure with disposal of hazardous waste and residues,including ash, scrubber water, and scrubber sludge (40 CFR2 6 4 . 3 5 1 ) .

• Compliance with additional general TSD facilityrequirements.

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<x>In addition, the regulations set the following performance 00

standards for incineration (40 CFR 2 6 4 . 3 4 3 ) ; including: 2>'Oil• Achieve a destruction and removal efficiency (DRE) of

9 9 . 9 9 9 9 percent (six 9s ) for each principal organichazardous constituent (POHC) in the waste feed for F-02Xwastes. A DRE of 9 9 . 9 9 percent (four 9s) is required fornon-F-02X wastes. For F-02X wastes, the DRE must bedemonstrated on POHCs that are more difficult to incineratethan tetra-, penta-, and hexachlorodibenzo-p-dioxins anddibenzofurans. In addition, the owner or operator of theincinerator must notify the Regional Administrator of hisintent to incinerate F-02X wastes.

• Reduce hydrogen chloride (HC1) emissions to 1.8 kg/hr or lpercent of the HC1 in the stack gas before entering anypollution control device.

• Not release particulate matter in excess of 180 mg/dscm(milligrams per dry standard cubic meter), corrected for theamount of oxygen in the stack gas.The ability to meet these performance standards must be

demonstrated during the trial burn period.Furthermore, monitoring of various parameters during

operation of the incinerator is required (40 CFR 2 6 4 . 3 4 7 ) . Theseoperating parameters include:• Combustion temperature• Waste feed rate• An indicator of combustion gas velocity• Carbon monoxide emissions

Finally, fugitive emissions must be controlled (40 CFR364.345) either by:• Keeping the combustion zone totally sealed.• Or maintaining a combustion zone pressure lower than

atmospheric pressure.The U . S . EPA has Standards for Owners and Operators of

Hazardous Waste Incinerators (40 CFR Parts 260, 261, 264, and2 7 0 ) . The standards establish risk-based emission limits forindividual toxic metals (Appendix VIII of 40 CFR Part 2 6 1 ) . TheU . S . EPA also regulates HC1 emissions using the same risk-basedapproach proposed for metals. The limits are back calculatedfrom ambient levels that the U . S . EPA believe pose acceptablehealth risk. To simplify this process, the U . S . EPA hasdeveloped conservative screening limits based on terrain andeffective stack height. If the screening limits are notexceeded, emissions do not pose unacceptable risk. If the

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screening limits are exceeded, however, site-specific dispersion »>,.analysis is required to demonstrate that emissions will not QOresult in an exceedance of acceptable ambient levels. The risk- j^.based controls are applied on a case-by-case basis to ensure that (^the existing technology-based standard is protective, o

0Existing regulations control organic emissions by the DREstandard in 40 CFR 2 6 4 . 3 4 3 ( a ) . This standard limits stackemissions of POHCs to 0.0001 percent (for dioxin-containingwaste) of the quantity of the POHC fed to the incinerator. Thestandard considers a POHC to be destroyed (or removed in ash orscrubber water) if it is not present in the stack emissions.

Given that stack gas CO is a conventional indicator ofcombustion efficiency and a conservative indicator of combustionupsets ( i . e . , poor combustion conditions), emissions to a deminimis level (100 ppmv) ensures high combustion efficiency andlow unbumed hydrocarbon emissions. The owner or operator wouldbe required to demonstrate that higher CO levels would not resultin high hydrocarbon emissions, in cases where the CO limit isexceeded.Delisting

If residues from treatment are delisted, they are no longerconsidered as RCRA hazardous wastes, and the wastes could beplaced in any landfill permitted to receive solid waste.Delisting of the material would involve petitioning the U . S . EPARegional Administrator to exclude the material from the hazardouswaste listing and to consider it nonhazardous. The petition muststate the need and justification for the delisting, and it mustinclude supportive documentation that demonstrates to theAdministrator why the material does not meet any of the criteriaunder which the original waste was listed. A rotary kiln wasused to incinerate wastes from the Vertac site at the U . S . EPACombustion Research Facility (CRF) in Jefferson, Arkansas.Scrubber brines and ash have been delisted by the U . S . EPA(Federal Register; Vol. 54, No. 71, 14 April 1 9 8 9 ) . A similardelisting procedure would be required for any F-Listed materialstreated at the site prior to disposal in a landfill not permittedto accept these F-listed wastes.Hazardous Waste Landfills

The technical requirements for an onsite consolidation unitmay, but are not required to, consider relevant and appropriatecertain design guidance (such as, for covers/caps, drainage,liners, stability, e t c . ) pertaining to RCRA facilities. RCRA-specific requirements for a hazardous waste landfill arepresented in 40 CFR 264.300 (Subpart N ) , which could beconsidered for a consolidation unit. These requirements would beapplicable to an onsite containment unit if residues from

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0000treatment were to be put into the unit without delisting. 40 CFR (s.

264.301 states that a RCRA landfill must have two or more liners (^that are designed, constructed, and installed to prevent omigration of wastes out of the landfill to the adjacent soil or c-<subsurface soil or groundwater during the active life of the >landfill. Other liner system requirements include: '• Constructed of materials that have appropriate chemical

properties and sufficient strength to prevent failure.• Placed upon a base capable of providing support to the

liner.• Installed to cover all earth likely to be in contact with

the waste or leachate.Furthermore, leachate collection systems are required above

and between the liners that are designed, constructed,maintained, and operated to collect and remove any leachate fromthe landfill. For a RCRA landfill, the leachate collection andremoval systems must be:• Chemically resistant to the waste managed or leachate

expected in the landfill.• Of sufficient strength and thickness to prevent collapse

under the pressure exerted by the overlying waste.• Designed and operated to prevent clogging through the

scheduled closure of the landfill.Furthermore, RCRA presents specific requirements for F-02X

wastes. In order to place F-02X wastes into a landfill, thelandfill must be operated in accordance with a management planfor these wastes that is approved by the Regional Administrator(40 CFR 2 6 4 . 3 1 7 ) . Approval of the management plan would be basedon the following factors:• The volume, physical, and chemical characteristics of the

waste, including migration potential.• The attenuative properties of the underlying and surrounding

soils.• The effectiveness of additional treatment, design, or

monitoring requirements.Finally, RCRA also presents monitoring, inspection,

surveying, record-keeping, closure, and post-closure carerequirements (40 CFR 264.303- 2 6 4 . 3 1 0 ) , and general facilityrequirements.

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A RCRA-equivalent consolidation/containment unit (CCU) will 05be constructed onsite as part of the remediation for OU1 for 00onsite disposal of demolition debris. The CCU will be designed t »to meet RCRA requirements. Provided adequate capacity is C7available, the CCU could be used for onsite disposal of soils. A 0similar cell or unit could be constructed if the required C-»capacity is not available. ' '

) •

Treatment Standards for Hazardous DebrisTreatment of hazardous debris is required if the debris is

to be land disposed. Debris must be treated using the technologyor technologies identified in Table 1 of 40 CFR Section 268.45,or the waste-specific treatment standards for the wastecontaminating the debris.

In general, the treatment standards for hazardous debris arenot applicable if the OU2 debris ( i . e . , manholes, sumps, sewers,and foundations) is consolidated and not land disposed. If thisdebris is managed in place, the hazardous debris standards may berelevant and appropriate.Clean Water Act (CWA)

The Clean Water Act (CWA) mandated the U . S . EPA to establishregulations to protect the quality of surface waters across thenation. The CWA may be applicable to treatment and discharge ofwater used as part of a remedial action.

Under the CWA, three interrelated areas were identified forregulation:• Establishment of water quality standards.• Establishment of stormwater runoff control.• Establishment of effluent standards (discharge limitations)

intended to ensure compliance with applicable water qualitystandards.Water quality standards represent chemical-specific

requirements; stormwater runoff controls and effluent standardsare action-based requirements. Each is addressed separatelybelow.Chemical-Specific RequirementsWater Quality Criteria (WQC)

CERCLA §121 states that remedial actions shall attainFederal water quality criteria where they are relevant andappropriate under the circumstances of the release or threatenedrelease. Water quality criteria are non-enforceable guidancedeveloped under the Clean Water Act (CWA) §304 but are used by

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the state, in conjunction with a designated use for a stream ®segment, to establish water quality standards under CWA §303. In determining the applicability or relevance and appropriateness of ^*water quality criteria, the most important factors to consider ^are the designated uses of the water, and the purposes for whichthe potential requirements are intended. Water quality criteriahave been developed based on:

0

• Protection of human health. These levels have beendeveloped based on two separate potential exposure pathways.The first criterion is based solely on consumption of fish,while the second criterion considers both consumption offish, and consumption of water.

• Protection of aquatic life. These levels have beendeveloped based on acute toxicity, and chronic toxicityeffects to aquatic organisms.Whether a water quality criterion is appropriate and which

form of the criterion is appropriate depends on the likelyroute(s) and receptors of exposure.Action-Specific RequirementsStormwater Runoff Control

The U. S. EPA has issued -regulations setting forth theNPDES permit application requirements for discharges ofstormwater from industrial activities (40 CFR 122, 123, and 124).An NPDES permit is required for all discharges of stormwater fromindustrial activities as defined in the November 1990regulations. In states which have been granted NPDES permittingauthority by the U. S. EPA, all NPDES permits are issued andadministered by the state regulatory agency. The ADPC&E has beengranted authority over the NPDES program. The requirements ofthe state NPDES program are discussed in Subsection 2 . 3 . 3 .

As a result of the previous onsite remedial action, the CPAis surrounded by a series of five concrete lined drainage ditchesand collection sumps. During a storm event the drainage ditchesdivert run-off to the sumps. The initial sump volume (firstflush) for each of the five sumps is diverted to the onsitetreatment plant. All remaining stormwater is discharged to RockyBranch Creek without treatment.Discharge to Publicly Owned Treatment Works (POTW)

Indirect discharge to a POTW is governed by pretreatmentregulations (Section 307(b) of the CWA. National pretreatmentstandards are addressed under 40 CFR 403.

40 CFR 403. 5 and local POTW regulations require that109

discharge comply with the local POTW pretreatment program, ^including POTW-specific pollutants, spill prevention program y^,requirements, and reporting and monitoring requirements. ^

0The requirements for discharge to a POTW will be applicable Qfor water generated during the remedial action for OU2 if the , ,current onsite water treatment system is used for treatment and , .discharge to the POTW is continued. Discharge criteria for theonsite water treatment plant will apply to these aqueous streams.The current system was designed and operated for discharge to theJacksonville Wastewater Treatment Plant in accordance with aprevious permit, however as part of the off-site remedial action,the treated effluent will be discharged into Rocky Branch Creekif the pending permit is approved. The system will allowcompliance with discharge limitations which have been proposed tocontrol the discharge to Rocky Branch Creek.

Use of the existing onsite treatment plant for generatedwastewaters is included in the alternatives to be discussed. Theexisting plant was constructed as part of an earlier onsiteremedial action. The plant may be used as currently operated, ormodified as needed, or a new plant may need to be constructed.If the existing plant is used as part of the OU2 remediation,existing discharge limitations may be considered indirect ARARs.Direct Discharge of Treatment System Effluents

Direct discharge of wastewaters to a surface water isgoverned by the NPDES permitting requirements. 40 CFR 122, asapplicable to point source discharges to waters of the UnitedStates, which requires:• The use of the Best Available Technology (BAT) economically

achievable to control toxic and nonconventional pollutants.• Use of best conventional control technology (BCT) is

required to control conventional pollutants. Technology-based limitations may be determined on a case-by-case basis.

• 40 CFR 122. 44 and state regulations approved under 40 CFR131 requires compliance with applicable Federally approvedstate water quality standards. These standards may be inaddition to or more stringent than other Federal standardsunder the CWA.

• 40 CFR 122. 44(e) requires that discharge limitations mustbe established at more stringent levels than technology-based standards for toxic pollutants.

• 40 CFR 125. 100 requires that Best Management Practices(BMP) be developed and implemented to prevent the release oftoxic constituents to surface waters.

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CM• 40 CFR 122. 41(i) require that discharge must be monitored 05

to assure compliance. Discharge will monitor the mass of I>each pollutant, the volume of effluent, and the frequency of CMdischarge and other measurements as appropriate. ®The direct discharge requirements may be applicable if

waters generated during the remediation are discharged to RockyBranch Creek. ADPC&E would establish discharge limitations whichwould apply to the site wastewasters if they are discharged toRocky Branch Creek. Water generated during the remedial actionfor OU2 would need to be treated to meet the discharge limits.Safe Drinking Water Act (SDWA)

The Safe Drinking Water Act (SDWA) (42 USC 300f et seq.)mandated the U. S. EPA to establish regulations to protectpublic health from contaminants in drinking water. The SDWA isnot directly applicable to OU2 media, but may be indirectlyapplicable as a result of migration of site-related compoundsfrom OU2 media into groundwater. Potential SDWA ARARs identifiedare chemical-specific as discussed individually below. Nolocation-specific or action-specific ARARs were noted.Chemical-Specific Requirements

The U. S EPA has promulgated primary and secondary drinkingwater standards that are applicable to public water systems.Public water systems are defined as systems for the provision ofpiped water for human consumption with at least 25 persons.Primary drinking water standards are enforceable standards thatare not to be exceeded in public water supplies. Secondarydrinking water standards are nonenforceable (at the Federallevel) standards that are intended to serve as guidelines for useby states in regulating water supplies.National Primary Drinking Water Standards

National Primary Drinking Water Standards are established in40 CFR 141 and are expressed as maximum contaminant limits(MCLs). MCLs for 30 toxic compounds, including the 14 compoundsadopted as RCRA MCLs, have been adopted as enforceable standardsfor public drinking water systems (40 CFR 141.11-141.16). An MCLis required to reflect the technical and economic feasibility ofremoving the contaminant from the water supply. MCLs for eachcontaminant regulated must be set as close as feasible to the MCLgoal for that contaminant, given the best available technologyand treatment techniques.

The SDWA (40 CFR 142.4 and 142.5) allows public watersuppliers to obtain exemptions and variances from complying withMCLs under certain situations. However, it must be shown thatnoncompliance will not result in an unreasonable risk to human

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health. WOSMCL goals (MCLGs) (formerly known as recommended MCLs or *"

RMCLs) are nonenforceable health goals for public water systems. w<<The U. S. EPA has promulgated MCLGs for 9 contaminants (40 CFR °141.50-141.51) and has proposed MCLGs for 40 others (50 FR c:>4 6 9 3 6 ) . MCLGs are set at levels that would result in no known oranticipated adverse health effects with an adequate margin ofsafety.Secondary Drinking Water StandardsSecondary Drinking Water Standards are established for 13parameters in 40 CPR 143 and are expressed as Secondary MaximumContaminant Levels (SMCLs). The SMCLs are nonenforceable (at theFederal level) aesthetic-based guidelines e. g. , taste and odorthat consider available treatment technologies and cost oftreatment.The Clean Air Act

The Clean Air Act (CAA) (42 USC 7401 et seq. ) and Clean AirAct Amendments of 1990 mandated the U. S. EPA to establishregulations to protect ambient air quality. In response to thismandate, the U. S. EPA directed the following:• Establishment of National Ambient Air Quality Standards

(NAAQS).• Establishment of maximum emission standards as expressed

under the National Emission Standards for Hazardous AirPollutants (NESHAP). These standards apply to emissionsfrom specific sources, and are not ARAR to activities thatare expected at the Vertac site.

• Establishment of maximum emission standards as expressedunder the New Source Performance Standards (NSPS).

Chemical-Specific RequirementsNational Ambient Air Quality Standards

National Ambient Air Quality Standards (NAAQS) (40 CFR 50)have been developed by the U. S. EPA for seven classes ofpollutants: particulates, sulfur oxides, nitrogen oxides,hydrocarbons, oxidants (ozone), carbon monoxide, and lead. TheNAAQS focuses on two levels of control: primary and secondary.The primary standards apply exclusively to the protection ofhuman health, while the secondary standards are set to protectwelfare, including wildlife, climate, recreation, transportation,and economic values. A listing of NAAQS primary and secondarystandards is included in 40 CFR §50. It should be noted that

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^.these standards are not emission ( i . e . , discharge) standards, OSthey are standards to be met for the ambient air, after allowing t*-for mixing of the particular discharge with the ambient air. GNAAQS attainment requirements are applicable only to "major 0sources" which are pollutant-specific, or sources which emit 10 <-tons/year of a single regulated hazardous air pollutant (HAP) or25 tons/year of any combination of regulated pollutants (HAPs).The definition of "major sources" is also dependant on the localattainment classification. Pulaski County is designated as anozone maintenance area, therefore a "major source" is defined asany source with the uncontrolled potential to emit 100 tons/yearof volatile organic compounds (VOCs).

State Implementation Plans (SIP) are developed by individualstates and contain the actual abatement requirements necessary toachieve compliance with the NAAQS.

Ambient air monitoring during remediation may be part of theselected remedial action for OU2. Perimeter air samplers andreal-time ambient air monitors may be used to monitor ambient airquality onsite. Particulates would be the NAAQS contaminant ofgreatest concern onsite if soil excavation is required.Engineering controls would be necessary if particulateconcentrations in ambient air become a concern. VOC emissionswould be the NAAQS contaminant of concern if incineration werepart of a remedial action. The maximum achievable controltechnology (MACT) standards, which the U . S . EPA is in the processof developing, may apply.Action-Specific RequirementsNew Source Performance Standards

NSPS regulations (40 CFR 6 0 ) have been promulgated to coverparticulate discharges from a number of different types offacilities, including incinerators. Incineration regulations arelisted under Subpart E, Standard of Performance for Incinerators.The operating standard (40 CFR 60. 52) is that the discharge ofparticulate matter shall not exceed 180 mg/dscm (milligrams perdry standard cubic meter), corrected to 12% C02. This provisionapplies to incinerators with a charging rate exceeding 50 metrictons per day. It should be noted that this performance standardfor particulate matter matches that listed under the RCRAregulations for incinerators.

If the treatment process selected for OU2 has a chargingrate exceeding 50 tons per day, the NSPS may be applicable.However, the particulate standard stated above should be easilyattained using commercially available air pollution controlequipment.

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7 . 2 . 2 STATE ARARS ^05Regulation No. 2: Water Quality Standards for Surface Waters »s«<MPursuant to the Arkansas Water and Air Pollution Control Act <Q

(AWAPCA) and in compliance with the requirements of the Federal ^Water Pollution Control Act, the State of Arkansas has developedwater quality standards for all surface waters, interstate andintrastate. Established water quality standards are based uponpresent, future, and potential uses of the surface waters of thestate and criteria developed from statistical evaluations of pastwater quality conditions and a comprehensive study of least-disturbed, ecoregion reference streams. The standards aredesigned to: enhance the quality, value, and beneficial uses ofthe water resources of the state; aid in the prevention, control,and abatement of water pollution; provide for the protection andpropagation of fish and wildlife; and, provide for recreation inand on the water.

General standards for color, taste and odor, solids, toxics,and oil/grease have been developed. In addition specificstandards for temperature, turbidity, pH, dissolved oxygen,radioactivity, bacteria, toxics, nutrients, oil/grease, andmineral quality have been developed depending on the individualecoregions within the state. The site is situated within theArkansas River Valley Ecoregion.

Water quality standards relate to the existing onsitetreatment plant and its off-site discharges. As part of OU2,the existing treatment plant may be utilized to treat collectedstormwater and wastewaters generated as part of the remediation.Although the existing treatment plant currently discharges to alocal POTW, discharge limitations for discharge to Rocky BranchCreek have been proposed by ADPC&E.Regulation 3: Certification of Wastewater Utilities Personnel

Operators in responsible charge of wastewater treatmentfacilities are required to be licensed and certified by ADPC&E inorder to safeguard the public health and protect the waters ofthe state from pollution. Certification typically includes:training, classifying, and licensing of treatment plantoperators.Regulation 6 : State Administration of the National PollutantDischarge Elimination System (NPDES)

The technical requirements of an NPDES permit may apply ifwastewaters generated at the site are directly discharged intoRocky Branch Creek. Further, the technical requirements of astorm water permit may apply if stormwater discharges associatedwith the site remedial activities that involve disturbing more

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than five ( 5 ) acres are discharged to Rocky Branch Creek. An <0individual NPDES permit may be issued by the ADPC&E, or general OSpermit coverage may be obtained under the Departments General CNPDES Permit No. ARROOAOOO. Obtaining NPDES coverage for ^stormwater discharges requires submission of an individualapplication, or Notice-of-Intent (N01), development andimplementation of a Stormwater Pollution Prevention Plan, andpossibly stormwater sampling and monitoring.

The existing treatment plant onsite may be used to treatwastewaters generated as part of the OU2 remediation. Currentlythis treatment plant discharges to a local POTW in accordancewith a previous permit, however, as part of the off-site remedialaction, the treated effluent will go to Rocky Branch Creek. Thesystem will allow compliance with discharge limitations whichhave been proposed to control the discharge to Rocky BranchCreek.Regulation 23: Hazardous Waste Management Code

The Arkansas Hazardous Waste Management Act of 1979 and theArkansas Resource Reclamation Act of 1979 are known together asthe Arkansas Hazardous Waste Management Code (amended June,1 9 9 2 ) . This code resembles the federal hazardous wastemanagement regulations promulgated under RCRA. The ArkansasHazardous Waste Management Code does contain siting criteria(Section S) for a hazardous waste management facility. Such afacility may not be sited in the following areas:• An active fault zone.• A "regulatory floodway" as adopted by communities

participating in the National Flood Program.• A 100-year floodplain.• A recharge zone of sole source aquifer designated pursuant

to the SDWA.• Wetlands areas that are inundated or saturated by surface

water or ground water.In addition, no permit shall be issued for a hazardous waste

landfill facility or surface impoundment if such a facility islocated in the following areas:• Areas of high earthquake potential.• Areas having a soil that would be classified as vertisol.• Areas in which a stratum of limestone or similar rock of an

average thickness of more than 1 meter lie within 30 meters115

-) -tT>

of the base of the proposed liner system. os

Areas in which the liner bottom or in-place barrier soil is ^less than 10 feet above the historically high water table.

• Areas near a functioning private or public water supply thatwould constitute an unacceptable risk to the public healthor safety.

• Areas one-half mile from any occupied dwelling, church,school, hospital, or similarly occupied structure.

• Areas where the active portion of the facility is less than200 feet from the facility's property line, and less than300 feet from right-of-ways for roads and utilities.Section 13 of the Code includes performance standards in

addition to the provisions of 40 CFR 264, 265, and 270. WithinSection 13, it states that when it is technically feasible,destruction of hazardous waste should be accomplished byincineration utilizing currently available technology. Noacutely hazardous waste shall be disposed of in landfills in theState of Arkansas.

The consolidation/containment unit ( C C U ) , which is acomponent of many alternatives for OU2 media, will be designedand constructed as part of OU1. Therefore, siting criteriadiscussed above are not applicable but may be relevant andappropriate. Siting will be performed under OU1.Arkansas Solid Waste Management Code

Pursuant to the Arkansas Solid Waste Management Act of 1971,the Arkansas Solid Waste Management Code of 1984 (as amendedMarch, 1984) has been divided into six main chapters including( 1 ) preliminary provisions, ( 2 ) local solid waste managementsystems ( 3 ) permit application procedures, ( 4 ) permitting andoperational standards, ( 5 ) enforcement and ( 6 ) other provisions.Of particular interest are the permitting and operationalstandards to be followed when planning/designing a solid wastelandfill within the State including:• Testing - Geological characteristics would be required toindicate soil conditions, groundwater elevation andmovement, and subsurface characteristics.• Equipment - Verification of proper equipment available to

properly operate the landfill facility.• Geologic Structure - The subsoil and lithological structure

shall be such that there is reasonable assurance thatleachate from the landfill will not contaminate the ground

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00waters or surface waters of the state. ^r-• Sedimentation and Surface Water Control - The surface QQcontour of the area shall be such that surface runoff will onot flow through/into the fill area. C,t

• Water Table - Landfill operations will maintain a safe •vertical distance between deposited refuse and the maximumseasonal water table elevation and shall include suchmeasures necessary to prevent contamination of thegroundwater.

• Flooding - sites subjected to flooding shall be avoided.• Site Improvements - The following physical improvements

shall be made before a landfill site is placed in operation.The Site shall be adequately fenced, with an entrance gatethat can be locked and posted.All-weather operational roads shall be provided.Arrangements shall be made for fire-protection services.

• Operation - All operations of the landfill shall be inaccordance with the approved plans and the Arkansas SolidWaste Management Code.The CCU, which is a component of many alternatives for OU2

media, will be designed and constructed as part of OU1.Therefore, siting criteria discussed above are not applicable butmay be relevant and appropriate. Siting will be performed underOU1.Arkansas Water and Air Pollution Control Act (AWAPCA)

Subchapter 2 of the AWAPCA (relating to water pollution)provides the Arkansas Pollution Control and Ecology Commissionthe authority to prescribe:• Effluent standards specifying the maximum amounts or

concentrations and nature of the contaminants beingdischarged into the waters of the State of Arkansas or intoPOTWs.

• Requirements and standards for equipment and procedures formonitoring contaminant discharges at their sources.

• Water quality standards, performance standards, andpretreatment standards.In compliance with the requirements of Federal Water

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0505Pollution Control Act, the Arkansas Commission on Pollution ^>»,

Control and Ecology has established water quality standards for Qall surface waters, interstate and intrastate, of the State of QArkansas. C--

)Arkansas air pollution control regulations (Subchapter 3) i

resemble the national standards set forth by the U . S . EPA underthe CAA, but require preconstruction review by the State.Section 5 of the Arkansas Air Pollution Control Regulationsoutlines specific limitations for particulate emissions, and forvisible emission from new or modified sources. Particulateemission limits are based on the rate of material being processed(Ib/hr), visible emission standards are action specific.Arkansas Air Pollution Control Code

The Arkansas Air Pollution Control Code was derived from theAWAPCA and outlines permit requirements, and emission limits forsmall or nuisance sources not covered by the SIP. Particularinterest are Section 4 - Visible Emissions; Section 6 -Emissionof Particulate Matter from Incinerators; Section 7 - Emission ofParticulate Matter from Equipment; Section 8 - Emission ofParticulate Sulfur Compounds; Section 10 - Emission of AirContaminants Such as to Constitute Air Pollution; and Section11 - Control of Fugitive Emissions.Arkansas State Implementation Plan for Air Pollution Control

Promulgation and enforcement of the SIP (Regulation No. 1 9 ,September, 1993) is necessary for the attainment and maintenanceof the National Ambient Air Quality Standards (40 CFR Part 5 0 ) ,New Source Performance Standards (40 CFR Part 6 0 ) , Prevention ofSignificant Deterioration (40 CFR 52. 2 1 ) , and the NationalEmissions Standards for Hazardous Air Pollutants (40 CFR Part6 1 ) . The SIP is formatted into the following sections:

Protection of the National Ambient Air Quality Standards.Applicability, Permitting Procedure.General Emissions Limitations Applicable to Equipment.Upset Conditions, Revised Emissions Limitations.Sampling, Monitoring, and Reporting Requirements.Prevention of Significant Deterioration Supplement.Ill(d) Designated Facilities.Regulations for the Control of VOCs.The SIP was developed primarily to satisfy the requirements

of the Clean Air Act.Arkansas Noncriteria Air Pollutants Control Strategy

ADPC&E has implemented an evaluation of the emissions ofnoncriteria air pollutants from all sources in order to determine

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0if a permit should be issued or if an existing source should be Qrequired to retrofit control equipment. The Noncriteria Air QQPollutants Control Strategy (NAPCS) allows applicants to apply a 3 level evaluation of the emission source. The three levels are Qas follows: .• Level 1 Analysis - This analysis is based upon Threshold

Limit Values (TLVs) for chemical substances adopted by theAmerican Conference of Governmental Industrial Hygienists(ACGIH). According to NAPCS, the predicted ambient airconcentration of gases and vapors is considered acceptableif it is less than 1/100 of the ACGIH TLV. The ambientconcentration is determined by using appropriate atmosphericdispersion models over a 24-hour average. The spacingbetween receptors used in the model is 100 meters (in thearea of the highest concentration). The NAPCS may consider8 and 24-hour averages, first highs, as well as annualaverages for use in assessing risk.TLVs have been established for the following OU2-related

site compounds:Compound TLV2,4-D 10 mg/m3

2, 4 , 5 - T 10 mg/m3When the substance emitted is a particulate compound and

persistence in the environment is expected, the predicted annualaverage concentration is considered acceptable if it does notexceed the dosage mass of the LD50 expression divided by 10,000.

If the substance emitted is a herbicide, pesticide, orfungicide, the recommended application rate (in pounds/m2) isdivided by 30,000 to obtain the maximum allowable 24 ambientconcentration.• Level 2 Analysis - If the source fails the Level 1 analysis,

the applicant must demonstrate they are using controltechniques equivalent to lowest achievable emission rate(LAER) and submit toxicological and/or other data sufficientto demonstrate the ground level concentration predicted inLevel 1 will not adversely affect the public's health orwelfare.

• Level 3 Analysis - If the applicant is unable tosuccessfully demonstrate acceptance under Level 1 or 2analyses, then more appropriate mathematical models (usingsite-specific information), or ambient air monitoring can beperformed. Information gathered during Level 3 analysis isthen plugged back into the Level 1 and/or 2 analysis todetermine acceptance.

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The NAPCS may be applicable to remedial actions performed °onsite. A site-wide air monitoring program may be required to u—ensure compliance with this control strategy. ^

0Arkansas State Groundwater Quality Protection Strategy ,* •The objective of Arkansas' groundwater strategy is to

formulate and recommend a management program to protect thequality of.groundwater resources.

Arkansas' Groundwater Quality Protection Strategy outlineswater quality criteria for groundwater (drinking water) withinthe state. Arkansas has adopted the recommended standards fordrinking water set by the SDWA. The Arkansas Department ofHealth uses the National Primary Drinking Water Standards insetting the criteria to which public water supplies must adhere.

The Arkansas State Groundwater Quality Protection Standardis not directly applicable to OU2 media, but may be indirectlyrelevant as a result of the migration of site-related compoundsmigrating from OU2 media into groundwater.7 . 2 . 3 TO-BE-CONSIDERED (TBCs)City of Jacksonville Ordinances 604. 620. 684. and 877

Ordinance No. 620 sets forth uniform requirements fordirect discharge and indirect contributors into the wastewatercollection and treatment system for the City of Jacksonville,Arkansas, and enables the City to comply with all applicablestate and Federal laws required by the CWA of 1977 and theGeneral Pretreatment Regulations (40 CFR 4 0 3 ) .

Ordinance No. 684 is an ordinance amending Ordinance No.620, specifically listing additional chemical-specific pollutantlimitations for contributors into the wastewater and treatmentsystem for the City of Jacksonville.

Ordinance No. 877 is an ordinance amending Ordinances 620and 684, specifying that no industrial user shall dischargewastewater of sufficient strength to cause the 24-hour loading tothe POTW to exceed background levels by more than thosespecified, under this ordinance, for selected chemicals.

Ordinance No. 604 is an ordinance regulating theJacksonville sewer system and sets forth requirements andregulations for the use of public sewers and private sewagedisposal.8 . 0 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES

EPA is required to analyze each of the individual120

CMalternatives against a set of 9 criteria and develop a Qcomparative analysis that focuses upon the relative performance QQof each alternative against those criteria. ^

The nine evaluation criteria are as follows:1. Overall Protection of Public Health and the Environment

This criterion addresses the way in which a potential remedywould reduce, eliminate, or control the risks posed by the siteto human health and the environment. The methods used to achievean adequate level of protection may be through engineeringcontrols, treatment techniques, or other controls such asrestrictions on the future use of the site. Total elimination ofrisk is often impossible to achieve. However, a remedy mustminimize risk to assure that human health and the environmentwould be protected.2. Compliance with ARARs

Compliance with ARARs, or "applicable or relevant andappropriate laws and regulations," assures that a selected remedywill meet all related federal, state, and local requirements.The requirements may specify maximum concentrations of chemicalsthat can remain at a site; design or performance requirements fortreatment technologies; and restrictions that may limit potentialremedial activities at a site because of its location.3 . Long-Term Effectiveness or Permanence

This criterion addresses the ability of a potential remedyto reliably protect human health and the environment over time,after the remedial goals have been accomplished.4. Reduction of Toxicity, Mobility, or Volume of Contaminants

This criterion assesses how effectively a proposed remedywill address the contamination problems. Factors consideredinclude the nature of the treatment process; the amount ofhazardous materials that will be destroyed by the treatmentprocess; how effectively the process reduces the toxicity,mobility, or volume of waste; and the type and quantity ofcontamination that will remain after treatment.5. Short-Term Effectiveness

This criterion addresses the time factor. Technologiesoften require several years for implementation. A potentialremedy is evaluated for the length of time required forimplementation and the potential impact on human health and theenvironment during the remediation.

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00

CO6. Tmplementability 0

00Implementability addresses the ease with which a potential G

remedy can be put in place. Factors such as availability of 0materials and services are considered. C--7 . Cost *

Costs (including capital costs required for design andconstruction, and projected long-term maintenance costs) areconsidered and compared to the benefit that will result fromimplementing the remedy.8. State Acceptance

The state has an opportunity to review the FS and ProposedPlan and offer comments to U . S . EPA. A state may agree with,oppose, or have no comment on the U . S . EPA preferred alternative.9 . Community Acceptance

During the public comment period, interested persons ororganizations may comment on the alternatives. U . S . EPAcarefully considers these comments in making its finalselection. The comments are addressed in a document called aresponsiveness summary, which is part of this Record of Decision.

The nine criteria are categorized into three groups:threshold criteria, primary balancing criteria, and modifyingcriteria. The threshold criteria must be satisfied in order foran alternative to be eligible for selection. The primarybalancing criteria are used to weigh major tradeoffs amongalternatives. The modifying criteria are taken into accountafter public comment is received on the Proposed Plan.Threshold Criteria• Overall protection of human health and the environment.• Compliance with ARARs (applicable or relevant and

appropriate requirements of other Federal and Stateenvironmental statutes).

Primary Balancing CriteriaLong-term effectiveness and permanence.Reduction of toxicity, mobility, and volume throughtreatment.Short-term effectiveness.Implementability.Cost.

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Modifying Criteria• State acceptance.• Community acceptance.8.1 COMPARATIVE ANALYSIS OF REMEDIAL ALTERNATIVES

1. Overall Protection of Human Health and the EnvironmentAlternative S-1 (no action), does not provide adequate

protection of human health and the environment. Alternatives S-2through S-8 do not provide for adequate protection of humanhealth and the environment when considering the proposed TCDDcleanup standards of 50 ppb, 35 ppb, and 20 ppb presented in theFS (see EPA risk evaluation of soil cleanup levels for 2 , 3 , 7 , 8 -TCDD at the Vertac Superfund site). EPA has determined that a 5ppb action level, based on site specific risk factors for TCDDTEQ, is necessary to be protective of a future onsite unprotectedworker exposure scenario. However, in examining the relativeprotectiveness of Alternative S-2 through S-8 the following wascomparisons were made. Alternatives S-2 through S-8 pose varyingdegrees of potential short term risk during remedial actions.However, through appropriate health and safety measures andproper engineering controls adequate protection would be providedto the community and the workers during the remedial actions.

Alternatives S-2, S-7 and S-8 provide adequate long termprotection after completion of the remedial actions by isolatingthe contaminated soil. Alternative S-8 provides additionalprotection over S-2 and S-7 because all soil above the actionlevel is consolidated in the CCU. Alternatives S-3 and S-4provide additional long term protection as a result of permanentdestruction of the highest concentrations of TCDD. AlternativesS-5 and S-6 provide the greatest long term protection by treatingthe largest volume of contaminated soil. However, this is offsetby the additional short term risks, and substantial additionalcost for implementing Alternatives S-5 and S - 6 .

Alternative U-l, no further action, would not provideadequate protection to human health and the environment.Potential risks would continue at current conditions for anextended period of time. Alternatives U-2, and U-3 wouldprovide adequate short term protection to the community duringremediation activities, and U-3 would provide overall better longterm protection to human health and the environment.2. Compliance with Applicable or Relevant and Appropriate

Requirements (ARARs)At present there are no State or Federal regulations that

are applicable to Alternative S-1 (no action), although thisalternative is not protective of human health. Land disposal

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nft0restrictions are not applicable to consolidated or containerized

soils for the onsite landfilling component of Alternatives S-2 °^through S-8, as they would be consolidated within an area of G-0c.containment without treatment. For alternatives S-3 through S - 6 ,thermally treated soils would need to comply with land disposalrestrictions prior to disposal. Treatment and disposal of TCBspill-related material would comply with applicable requirements.

Leachate collected from the onsite landfill in AlternativesS-2 through S-8, and condensed water from Alternative S-3 wouldbe treated onsite through and the resulting discharge would haveto meet treatment/discharge requirements. Organic condensategenerated from thermal desorption in Alternative S-5 would betransported off-site for incineration, and would have to be incompliance with appropriate incineration/disposal requirements.

Off-site transportation of crystalline TCB and associatedspill soils in Alternatives S-2 through S-6 and desorbed liquidsgenerated in Alternative S-5 would comply with all applicabletransportation regulations.

Alternatives U-2 and U-3 would comply with ARARs. Treatmentstandards for hazardous debris are not applicable to undergroundstructures because the ( i . e . , manholes, sumps, sewers, etc) wouldnot be land disposed. Treatment and disposal standards areapplicable to the wastewater generated during the remedialactions. Wastewater generated from flushing of the industrialsewer, and from hydroblasting of foundations and curbs, would betreated at the onsite treatment plant in compliance withapplicable treatment and standards. Solids generated would beplaced in the onsite consolidation unit.3 . Long-Term Effectiveness and Permanence

Alternative S-1 (no action) does not provide for long-termprotection. Alternative S-2, S-7, and S-8 provides for thereduction in the migration and exposure pathways through cappingand/or landfilling contaminated soils. Alternatives S-3 and S-4provide for better long term protection through additionalreduction in toxicity by permanent destruction of some of thecontaminants through treatment. Alternatives S-5 and S-6 involvethe greatest treatment components and would provide the highestlong term protection by permanently destroying site contaminants.However, the high cost to implement the off-site incinerationalternative ( S - 6 ) and increased length of time to implement theonsite thermal desorption alternative ( S - 5 ) make these optionssomewhat problematic.

For Alternative U-l, the quantity of site-related compoundsin underground structures is expected to remain constant for theforeseeable future. For Alternatives U-2 and U-3, the residualconcentrations remaining after remediation would be minimal.

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<c0Alternative U-3 would provide for an additional level of long QQ

term protection by grouting up the sewer line, which would reduce rothe potential for collapse and transmission of groundwater, and ^sealing foundations and curbs would prevent contact with ^contaminants that cannot be removed by scarification.4. Reduction of Toxicity, Mobility, or Volume of the

Contaminants through TreatmentA significant reduction in toxicity, mobility and volume of

TCDD is not expected under Alternative S-1 (no action), anyreduction would occur through natural attenuation mechanisms.Alternatives S-2, S-7 and S-8, rely on capping and/or excavationand landfilling and would significantly reduce the mobility ofthe contaminants, but do not address reducing the toxicity orvolume of the contaminants. Alternative S-8 provides thegreatest reduction of the mobility of the three due to extensivesoil isolation. Alternatives S-3 and S-4 which incorporatecapping, landfilling, and treatment options address reducing thetoxicity, mobility and volume of TCDD at the site. These optionsinvolve treatment, capping, and landfilling. Alternatives S-5(onsite desorption), and S-6 (off-site incineration) addresssoils with TCDD concentrations greater than 50 ppb or 20 ppbdepending upon the option considered, would provide for thegreatest reduction in toxicity, mobility and volume of TCDD ofall the options reviewed. However, drawbacks to these optionsinclude the estimated 4 years o^ onsite treatment time requiredunder Alternative S-5 and the extremely high cost ofimplementation associated with Alternative S - 6 .

Alternative U-l would not provide for the reduction oftoxicity, mobility, and volume of contaminants associated withthese structures. Under Alternatives U-2 and U-3, contaminantsare removed from theses structures, thereby significantlyreducing their toxicity, mobility and volume.5. Short-Term Effectiveness

All action alternatives require between 2 and 5 years toimplement. Remedial actions involving capping and excavation andlandfilling are generally faster to implement than those optionsrequiring combinations of onsite/off-site treatment, capping,and landfilling.

Alternative S-1 (no action) poses the least short-termimpact to the community and site workers. Alternatives S-2through S-8 pose some potential short term impact to thecommunity and workers from dust generated during materialhandling activities. Alternatives S-3 through S-6 poseadditional impact associated with the operation of treatmentsystems. Short-term impact posed by Alternatives S-5 and S-6 arehigher than for the other alternatives due to the relatively

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j>-large volume of soil to be excavated and treated. Alternative S- 05 involves transportation of relatively small amounts of high 00concentration liquids off-site, in addition to the risks posed by <Mexcavation and treatment of the largest volume of contaminated 0soil. C

No short term impact would result from implementation of 'Alternative U-l. Short term impacts associated with AlternativesU-2 and U-3 are primarily from dust generated during remedialactivities. Appropriate engineering controls will be used fordust suppression, and other measures necessary to preventairborne releases.6. Implementability

Alternative S-1 is the easiest to implement because itrequires no further action. Alternatives S-2, S-7, and S-8(capping and landfilling options) are relatively simple toimplement because they use conventual construction techniques.Alternatives S-3, and S-4 are more difficult because they requiretemporary soil storage and onsite treatment of soils. Therequirements for implementing Alternative S-6 is similar to S-3and S-4 except the volume of soils requiring excavation andtreatment is substantially larger. Alternative S-5 is the mostdifficult to implement because it involves the same amount ofsoil involved in S - 6 , except that both onsite and off-sitetreatment options are in effect.

Alternative U-l can easily be implemented as it does notrequire any further action. Alternatives U-2 and U-3 can beimplemented using standard and specialized equipment.Technologies and technical expertise associated with thealternatives are readily available.7 . Cost

The costs associated with the alternatives described rangedfrom $5,896,000 (Alternative S-2) to $164,601,000 (AlternativeS - 6 ) . Annual O&M costs ranged from $10,400 (Alternatives S-5 andS - 6 ) to $37,700 (S-2 to S - 4 ) .

The cost to implement Alternatives U-2 and U-3 are$1,229,000 and $1,359,000, respectively.8. State Acceptance

Under the Superfund law, EPA is required to ensure thatStates have a meaningful and continuing role in remedy selectionand execution. While States are not required to formally concurwith EPA-selected remedies, if Federally funded they mustcontribute 10 percent of the remedy's construction cost andformally concur with the deletion of sites from the National

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00Priorities List upon completion of the remediation process. For ^,these reasons, EPA has attempted to keep the State staff informed QQregarding the process and has briefed the State on several <occasions concerning the remedial alternatives considered in the QFS and the preferred option in the Proposed Plan. C

The ADPC&E has reviewed the PS, the Proposed Plan, and hasprovided EPA comments on this ROD, which can be found in AppendixC.9. Community Acceptance

EPA recognizes that the community in which a Superfund siteis located is the principal beneficiary of all remedial actionsundertaken. EPA also recognizes that it is its responsibility toinform interested citizens of the nature of Superfundenvironmental problems and solutions, and to learn from thecommunity what its desires are regarding theses sites.

EPA has undertaken an extensive effort to solicit input fromthe community on the various remedial options being consideredfor this Operable Unit. Several concerns which were raised bythe community included; 1) that if a landfill was necessary atthe site, that it should be located at the greatest distance awayfrom the nearest residences and that it should be kept as smallas possible, 2) that for the restricted access portion of thesite (area that would remain fenced) workers should not have towear "moonsuits" to conduct their daily activities, 3) that anattempt should be made to return a portion of the site back tocommercial/industrial productivity, 4) that the cleanup level fordioxin within the fenced area should be no greater than 5 ppb,and 5) that for the area of the site that would be redeveloped ascommercial/industrial that the dioxin cleanup level should be amaximum of 1 ppb. EPA, in its selected remedy, has achievedthese community objectives.9 . 0 THE SELECTED PgMrcnv

Based upon consideration of the requirements of CERCLA, thedetailed analysis of the alternatives using the nine evaluationcriteria, consultation with the Arkansas Department of PollutionControl and Ecology, and public comments, EPA has determined thatAlternatives S-2 (with the modifications described below foronsite surface soils) and U-3, are the most appropriate remediesfor the Vertac Operable Unit 2 media. One component of theselected remedies uses a combination of capping in place andexcavation and landfilling to address low level threats posed bycontaminated soil media.

Under this remedy, the Vertac site will be roughly dividedin half from east to west, except for a portion of the site alongMarshall Road which runs north to south. After remediation, the

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05northern portion of the site will have unrestricted access for 0commercial/industrial development. The southern half of the 00site, however, will remain fenced and access will be limited to ^workers conducting required maintenance activities. Figure 13 0depicts the areas of the site that will remain fenced in relation c-to the portion of the site that will have unrestricted commercialaccess.

A summary of the selected remedy is presented below.9.1 SOILS AMD SEDIMENT MEDIA

1) Onsifce Surface SoilsAREAS WITHIN THE RESTRICTED ACCESS (FENCED) PORTION OF THE SITE

The selected remedy for the Vertac onsite soils media isAlternative S-2 with the exception that the action levels for•dioxin contaminated soils are different. Soils with dioxinconcentrations exceeding the action level of 5 ppb, but less than1,000 ppb will be capped in place. Capping would involvecovering the contaminated surface soil with a 6 inch layer ofcompacted soil, a 6 inch layer of topsoil, and revegetation.Approximately 485,000 square feet of the site would be capped.

Soils with dioxin concentrations greater than 1,000 ppb(approximately 400 cubic yards) will be excavated andconsolidated into an onsite subtitle-C landfill. Excavated areaswould be backfilled and compacted with soil, including 6 inchesof topsoil (to return it to pre-excavation grade), andrevegetated. Some surface drainage modifications may be used tocontol runon and runof, thereby minimizing the potential for thedeterioration of the soil cap.

Deed restrictions would be sought to limit the future use ofthis portion of the property consistent with a waste disposalsite.AREAS OUTSIDE THE RESTRICTED ACCESS (FENCED) PORTION OF THE SITE

Soils with dioxin concentrations exceeding the action levelof 1 ppb will be excavated and consolidated into the onsitelandfill. Excavated areas will be backfilled with clean soil,graded, and revegetated.2) Crystalline Tetrachlorobenzene (TCB) and Soils associated

with the TCB spillThis component of the remedy calls for the excavation and

off-site incineration of the crystalline TCB, and TCB associatedspill soils where the TCB concentration exceeds a 500 ppm actionlevel. Excavated areas would be backfilled with clean fill,

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BITE MAP, VERTAC SITEJACKSONVILLE, ARKANSAS

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graded and revegitated. It has been estimated in the RI thatthere are approximately 1,400 cubic yards (2,100 tons) of ^crystalline TCB and associated soils for costing purposes. The T-Iactual volume of material will be determined during the remedial °0action. CQ03) Bagged Soils from Residential Areas c

This component of the remedy calls for the consolidation ofapproximately 2,770 cubic yards (4,155 tons) of dioxincontaminated soils removed from residential yards in 1988 intothe onsite RCRA compliant CCU. Dioxin concentrations in thebagged soils range between 13 ppb and 55 ppb TCDD. The dioxinconcentrations found in the bagged soils are consistent withthose being landfilled from onsite areas.4) Off-site Soils from the Residential Portions of Bayou Meto

and Rocky Branch Creek Floodplain AreasThis component of the remedy calls for the excavation of

approximately 4,100 cubic yards ( 6 , 1 5 0 tons) of dioxincontaminated soils from along Rocky Branch Creek and Bayou Metoand consolidation of this material into the onsite RCRA compliantCCU that is being designed for OU1 building debris.5) Dewatered Sludges from the Old Sewage Treatment Plant Sludge

DigesterThis component of the remedy calls for the consolidation of

approximately 800 cubic yards (1,200 tons) of dewatered digestersludges from the Old Sewage Treatment Plant into the onsite RCRAcompliant CCU. The dioxin concentrations found in the sewagetreatment plant digester are consistent with those beinglandfilled from onsite areas.

The cost to implement Alternative S-2, with above mentionedchanges in action levels, is estimated to be $7,702,419.9 . 2 UNDERGROUND UTILITIES & TANKS

The selected remedy for addressing the contaminantsassociated with these structures at the site is Alternative U-3.In addition, the underground chemical sewer lines will be cleanedto remove solids and filled with grout. Cuttoff barriers will beinstalled around various underground utility lines to preventshallow water migration along these lines. Underground fuelstorage tanks will be drained and the fuel will either berecycled or incinerated off-site. Foundations and curbs will becleaned through surface scarification, and areas where persistentstaining exists surface sealing will also be employed.

The cost to implement Alternative U-3, for the underground130

utilities lines, underground tanks, building and equipmentfoundations, and curbs is estimated at $1,359,000.

<^3•r-100(M

The estimated cost to implement the selected remedy is ®$9 , 0 6 1 , 4 1 9 . The annual O&M (operations and maintenance) costs is cestimated at $37,700. A more detailed estimate of the annual O&Mcost will be provided in the site O&M plan (developed during theremedial design).10.0 STATUTORY DETERMINATIONS

EPA's primary responsibility at Superfund sites is to selectremedial actions that are protective of human health and theenvironment. Section 121 of CERCLA also requires that theselected remedial action comply with applicable or relevant andappropriate environmental standards established under Federal andState environmental laws, unless a waiver is granted. Theselected remedy must be cost-effective and utilize permanentsolutions and alternative technologies or resource recoverytechnologies to the maximum extent practicable. The Statute alsocontains a preference for remedies that employ treatment thatpermanently and significantly reduce the volume, toxicity, ormobility of hazardous wastes as a principal element. Thefollowing sections discuss how the selected remedy meets thestatutory requirements.10.1 PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT

The selected remedy is protective of human health and theenvironment. The remedial action objectives and goals specifiedin section of the ROD will be met.

The remedy for the site soils, sediments and sludges,underground utility lines, and underground tanks is protective ofhuman heath and environment because:1) Soils within the restricted access area of the site that arehighly contaminated will be excavated and consolidated into anonsite Subtitle-C RCRA landfill. Soils that contain lower levelsof contaminants will be capped in-place. Both excavation andconsolidation into a RCRA landfill, and capping in place, willsubstantially reduce the mobility of the site contaminants, andprevents direct exposure through dermal contact, inhalation oringestion by future site workers maintaining the restrictedaccess area. Excavation and consolidation of the highly andmoderately contaminated soils should prevent the threat ofleaching to ground water.2) Soils within the area of the site designated forcommercial/industrial re-development (outside the restrictedaccess area) will be excavated and consolidated into the onsiteSubtitle-C landfill. Concentration of contaminates that will

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remain within this area will be below those required to beprotective of human health and the environment, and unrestricted (commercial access will possible, -i

003) Crystalline TCB and TCB contaminated soils above health C .based limits will be excavated and transported off-site for 0incineration. By permanently treating this waste at an off-sitefacility, the possibility of direct contact exposure iseliminated.4) Soils excavated from the Rocky Branch Creek, bagged soilsfrom the residential area, and sediments and sludges from theold sewage treatment plant will be consolidated into the onsiteSubtitle-C landfill. Excavation and consolidation of thesesediments into a RCRA landfill will substantially reduce themobility of these contaminants, and prevents direct exposurethrough dermal contact, inhalation or ingestion by the public whomay come into contact with these materials.5) Underground utility lines and underground fuel storage tankswill be closed and/or grouted to prevent the possibility ofground water contaminant migration and leaching.6 ) Building foundations and curbed areas will be cleaned usinghydroblasting, scarification and epoxy sealing. Afterremediation, these structures will not present an exposure hazardto future workers.

Short term risks associated with the selected remedy can becontrolled by proper design and implementation. No adversecross-media impacts are expected from implementation of theselected remedy.10.2 COMPLIANCE WITH ARARs

The selected remedy for site soils, sediments and sludges,underground utility lines, and underground tanks, will complywith all ARARs identified for the site. The ARARs for theselected remedy are presented below:

Because excavation of the soils and consolidation in the CCUoccur within the area of containment, and because there is notreatment involved, the land disposal restrictions apply. Inaddition, these restrictions do not apply to OU1 soils, becausethey were also excavated from within the area of containment andhave not been treated. The RCRA minimum technology requirements(MTRs) for landfills are not applicable to the CCU, however, theMTRs, are relevant and appropriate since the excavated soilswould be considered listed wastes, if they were removed from thesite; therefore the CCU will be designed to equivalent to MTRs.There are no ARARs for placement of clean soil over areas withdioxin contamination.

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Crystalline TCB, and spill related soils would be excavated 31and taken off site for treatment; therefore the RCRA T-Iclassification and listing as K085 hazardous waste would be ooapplicable. The waste classification is provided in 40 CFR CM261.32 and the waste is listed based on toxicity. The land 0disposal restrictions indicate that K085-listed waste must be C-/treated to concentrations of constituents specified in 40 CFR268.43 prior to land disposal. Transportation of crystalline TCBand spill related soils for offsite treatment/disposal would needto comply with all the requirements set forth under 40 CFR107,171-177, and 263, the Hazardous Materials Transportation Act(49 USC 1801-1813), and state hazardous waste transportationregulations.

The National Ambient Air Quality Standards may not beapplicable to this alternative, since these standards areapplicable only to "major sources" or sources that emit over 10to 25 tons per year of a regulated pollutant. The standards,however, are relevant and appropriate because respirable dustwill be generated during the cleanup. In addition, the Arkansasambient air quality standards as described in the Non-criteriaPollution Control Strategy would be applicable.

Aqueous waste generated during the remediation activities,such as decontamination water and leachate from the CCU will beprocessed through the onsite water treatment system. Water fromthis treatment system would be discharged to surface waters andas such would have to meet criteria equivalent to a Clean WaterAct NPDES permit for effluent concentration and flow.

Erosion and sediment controls during excavation,backfilling, regrading, and revegitation would have to complywith local regulations.10.3 COST EFFECTIVENESS

The selected remedy for Operable Unit 2 media is costeffective and is fully protective of human health and theenvironment based on future land use objectives. Section 300.430( f ) ( i i ) ( D ) of the NCP requires EPA to determine cost-effectiveness by evaluating the following three of the fivebalancing criteria to determine overall effectiveness: long-termeffectiveness and permanence, reduction of toxicity, mobility, orvolume, and short term effectiveness. Overall effectiveness isthen compared to cost to ensure that the remedy is costeffective. EPA believes that the selected remedy meets thesecriteria.

The estimated present worth cost for the selected remedy forsoils, sediments and sludges for areas that will remain fencedand areas outside the fence is $ 9 , 0 6 1 , 4 1 9 . The variation inremedy costs evaluated for these media ranged from $5,896,000 for

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Alternative S-2, with higher site action levels to $164,601,000for a total incineration remedy. Even though the selected remedy 10does not provide for a reduction in the toxicity or volume of —ldioxin in site soils, landfilling and capping will substantially 00reduce the mobility of the contaminant. The reduction in Gtoxicity and volume of dioxin as a site contaminant has been 0adequately addressed for this site under different Operable C.Units.

t

10.4 UTILIZATION OF PERMANENT SOLUTIONS AND ALTERNATIVETREATMENT TECHNOLOGIES TO THE MAXIMUM EXTENT PRACTICABLE

EPA has determined that the selected remedy represents themaximum extent to which permanent solutions and treatmenttechnologies can be utilized in a cost-effective manner for thisoperable unit.

Of those alternatives that were protective of human healthand the environment, and comply with ARARs, EPA has determinedthat the selected remedies provide the best balance of trade-offsin terms of long-term effectiveness and permanence, reduction intoxicity, mobility, or volume achieved through treatment, short-term effectiveness, implementability, costs, and taking intoconsideration State and community concerns.

The remedy meets the statutory preference for treatment as aprincipal element.10.5 PREFERENCE FOR TREATMENT AS A PRINCIPAL ELEMENT

EPA has determined though its evaluation of the alternativesthat the extent to which treatment should be practically beemployed ( i . e . , either onsite thermal desorption, onsiteincineration, or offsite incineration) for dioxin contaminatedsoils) is none. TCB contaminated soils, however, will beexcavated and transported off-site for treatment.

When evaluating the Vertac site and each of the six operableunits as a whole, it can be seen that a substantial amount oftreatment, both onsite and offsite, have been employed to addressprincipal threats at the site. Examples of onsite treatmentinclude the incineration of approximately 29,000 drums (10,000tons) of dioxin containing organic liquids. The dioxinconcentration in these drums was one to several orders ofmagnitude greater than that generally found in the Vertac sitesoils. In addition, the contents of the abandoned tanks at thesite, oily leachate from the french drain system, andcontaminated carbon from ground water treatment operation willalso be treated by incineration at an off-site facility and willexceed approximately 5,000 additional tons of material. As such,most of the dioxin at the site, which poses a principal threat,has or will be treated during site remediation efforts.

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All soils within the fenced portion of the site that exceed ^1,000 ppb will be excavated and placed into the onsite landfill. ^By landfilling all grids over 1,000 ppb approximately 42 percent QQof all dioxin in site soils will be contained. By capping the QQremaining site soils within the fenced area down to 5 ppb an Qadditional 57 percent of the dioxin will be immobilized. Thus, ^this remedy will either contain or immobilize over 99 percent ofthe dioxin found in the Vertac soils. The total amount of dioxinpresent in site soils covered under this operable unit comprisesonly about 1 to 5 percent of the amount of dioxin that was buriedin onsite landfills under the 1984 Court Ordered Remedy. Thus,the amount of dioxin that will be remediated via the cappingcomponent of the selected remedy will be approximately 0.5 to 1percent of the dioxin that has been landfilled at the site underthis, and/or past remedial efforts.

For areas located outside the fence, all soils greater than1 ppb will be excavated and landfilled onsite. The lower actionlevel has been set in order to provide additional protection forportions of the site that are slated for commercial/industrialredevelopment.11.0 DOCUMENTATION OF SIGNIFICANT CHANGES

The proposed plan for Operable Unit 2 media at the Vertacsite was released to the public in May 1995.

The modifications that have been made to the Record ofDecision for Operable Unit 2 media, are the result of twofundamental changes; 1) the preference for treatment of principalthreats has been met under other remedial activities at the site,and 2) that the future landuse scenario for the southern 100acres of the site should involve long-term restricted access,rather than extensive potential future commercial/industrialredevelopment.

In the proposed plan, EPA had origionally envisioned thatapproximately 50 percent of the southern 100 acres of the sitewould eventually be returned to commercial/industrial use.However, after re-evaluating the long-term operational andmaintenance requirements for this area of the site, ( i . e . ,maintaining the caps on the existing site burial areas, new thesubtitle-C landfill, and operation and maintenance of the groundwater treatment system) EPA believes that these operations willsubstantially reduce the chance for extensive futureredevelopment opportunities on the southern 100 acres. Becauseaccess to this area of the site will remain restricted (exceptfor site maintenance workers), other remedial options presentedin the OU2 FS, and proposed plan, such as capping, present a morecost effective means of cleanup, that are fully protective ofhuman health and the environment.

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The selected remedy for the Operable Unit 2 media differs i>significantly from EPAs proposed plan in several areas, they T-Iinclude: 00

(M1 ) . Offsite incineration is no longer a component in the 0

selected remedy. 0The proposed plan called for the excavation and offsite • •incineration of the 8 most highly contaminated soils gridsat the site (approximately 2,000 tons).EPAs original rational for incinerating the 8 most highlycontaminated grids (out of a total of 461) at the site wasbased on EPAs preference for treatment of principal threatsand permanence of remedy. Approximately 72 percent of theTCDD in site soils would have been treated at an offsitefacility.After re-evaluating all remedial activities at the site, EPAhas determined that the preference for treatment ofprincipal threats has been met (see Section 10.5 of thisROD) .

2 ) . The volume of TCDD material that was proposed forconsolidation into the onsite subtitle-C landfill within thefenced portion of the site has been reduced.The proposed plan called for the excavation andconsolidation of approximately 104 grids or 17,000 cubicyards of TCDD contaminated soil into the onsite landfill.The selected remedy will require that the 2 soil grids thathave the highest TCDD concentrations (approximately 400cubic yards) be excavated and consolidated within the onsitelandfill. This represents approximately 40 percent of allthe dioxin present within site soils.Because most of the southern 100 acres of the site will nowremain behind a secure fence, and future development will berestricted though administrative controls, assumptions usedto develop exposure scenarios for future site workers havebeen re-evaluated.

3 ) . Inclusion of capping of lower concentration TCDDcontaminated soils within the fenced portion of the site.The proposed plan did not include capping of TCDDcontaminated soil as a remedial element. The selectedremedy will call for the capping of all soils within thearea of the site that will remain fenced with 1 foot ofclean soil. By capping all soil grids that have TCDDconcentrations greater than 5 ppb. with the exception of thetwo grids that will be landfilled, over 9 9 percent of the

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dioxin at the site will be immobilized.4 ) . TCDD contaminated soils outside the fenced area will be

excavated and landfilled onsite where the concentrationexceeds 1 ppb.The proposed plan called for the excavation andconsolidation of TCDD contaminated soils into the onsitelandfill where the concentration exceeded 5 ppb. The 1 ppbcleanup level provides for a more protective remedy forareas of the site that are slated for commercial/industrialredevelopment.All other elements of the proposed plan remain unchanged in

the selected remedy.The changes discussed above were fully evaluated as other

remedial options considered in the OU2 FS and proposed plan.EPAs selected remedy is a modification of Alternative S-2 whichaddressed both landfilling and capping of dioxin contaminatedsoils. The difference between the selected remedy andalternative S-2 is that EPA is requiring a more conservativeaction level to trigger capping, i . e . , 5 ppb rather than 50 ppb,and would require soils greater than 1,000 ppb to be excavate andlandfilled onsite, rather than 500 ppb. The capping element ofthe selected remedy is responsive to comments received during thepublic comment period, that the size of the onsite landfillshould be kept to a minimum.

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