\ DECLARATION of the RECORD OP DECISION OPERABLE UNIT POUR Site NAME AND LOCATION Ciba-Geigy Site Mclntoah, Washington County, Alabama STATEMENT OP BASIS AND PURPOSE This decision document (Record of Decision), represents the selected remedial action for Operable Unit Pour for the Ciba-Geigy Site, Mclntosh, Alabama, developed in accordance with the Comprehensive Environmental Response, Compensation and Liability Act of 1980 (CERCLA), as amended by the Superfund Amendments and Reauthorization Act of 1986 (SARA) 42 U.S.C. Section 9601 fll seq.. and to the extent practicable, the National Contingency Plan (NCP) 40 CPR Part 300. This decision is based on the administrative record for the Ciba-Geigy Site. The State of Alabama has concurred on the selected remedy. ASSESSMENT OF THE Site Actual or threatened releases of hazardous substances from the Ciba-Geigy Site, if not addressed by implementing the response action selected in this ROD, may present an imminent and substantial endangerment to public health, welfare or the environment. DESCRIPTION OF SELECTED REMEDY This operable unit is the third of four proposed operable units. The first operable unit at this Site addressed contamination of the shallow (alluvial) aquifer. Operable unit two addressed a principal threat, the highly contaminated soils and sludges at ten of the eleven former waste management areas. Operable unit three will address contamination within the floodplain including the effluent ditch (previously called the lower portions of the dilute ditch) and areas in the Tombigbee River within close proximity to the Site. Operable unit four, which is the .subject of this Record of Decision, addresses contamination in former'waste management area 8 (the area not addressed in OUf2).
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DECLARATIONof the
RECORD OP DECISIONOPERABLE UNIT POUR
Site NAME AND LOCATIONCiba-Geigy SiteMclntoah, Washington County, Alabama
STATEMENT OP BASIS AND PURPOSE
This decision document (Record of Decision), represents the selectedremedial action for Operable Unit Pour for the Ciba-Geigy Site,Mclntosh, Alabama, developed in accordance with the ComprehensiveEnvironmental Response, Compensation and Liability Act of 1980(CERCLA), as amended by the Superfund Amendments and ReauthorizationAct of 1986 (SARA) 42 U.S.C. Section 9601 fll seq.. and to the extentpracticable, the National Contingency Plan (NCP) 40 CPR Part 300.
This decision is based on the administrative record for the Ciba-GeigySite.
The State of Alabama has concurred on the selected remedy.
ASSESSMENT OF THE Site
Actual or threatened releases of hazardous substances from theCiba-Geigy Site, if not addressed by implementing the response actionselected in this ROD, may present an imminent and substantialendangerment to public health, welfare or the environment.
DESCRIPTION OF SELECTED REMEDY
This operable unit is the third of four proposed operable units. Thefirst operable unit at this Site addressed contamination of theshallow (alluvial) aquifer. Operable unit two addressed a principalthreat, the highly contaminated soils and sludges at ten of the elevenformer waste management areas. Operable unit three will addresscontamination within the floodplain including the effluent ditch(previously called the lower portions of the dilute ditch) and areasin the Tombigbee River within close proximity to the Site. Operableunit four, which is the .subject of this Record of Decision, addressescontamination in former'waste management area 8 (the area notaddressed in OUf2).
The _ „_includes
•ajor component! of the selected remedy for operable unit four.ude t
Excavation of approximately 63,000 cubic yards of contaminated•oil* and sludges until established cleanup levels are reached oruntil excavation limits are reached.
Solidification/stabilization of up to 46,000 cubic yards ofmoderately contaminated soils and sludge containing no gamma-BHCand less than 2,500 ppm total organics, as an innovativeapplication of this technology which may be proven effectiveduring the remedial design;
Utilization of an innovative thermal technology or dechlorinationif proven effective during the remedial design for treatment orpretreatment to LOR treatabillty variances of contaminated soils;
On-site thermal treatment of approximately 17,000 cubic yards ofhighly contaminated soils and sludge and of waste not amenable tofinal treatment using the innovative technology dechlorination orthe innovative application of solidification/stabilization (up to46,000 cubic yards);
Disposal of treated soil and residual ash from the thermaltreatment process in an on-site RCRA Minimum Technology Subtitle Clandvault(s);
In-situ stabilization/fixation treatment of approximately 46,000cubic yards of iron slurry waste;
In-situ soil flushing combined with isolation walls and extractionwells to remediate areas where the risk based cleanup levels arenot achieved before excavation is terminated. Innovativetechnologies (in-situ vacuum extraction or in-situ bioremediation)may also be used in addition to or instead of in-situ soilflushing, if during the remedial design either technology is foundto be effective in reducing contaminant concentrations in the soiland is cost effective. If either technology is proven to be moreeffective than in-situ soil flushing in reducing theconcentrations of the contaminants in the soil and more coateffective, it will be used instead of in-situ soil flushing. Ifeither technology is not as effective as in-situ soil flushing inreducing the concentration of the contaminants in the soil it willnot be utilised in place of in-situ soil flushing, however, it maybe used in concert with in-situ soil flushing if the combinationenhances the remediation in reaching cleanup levels and is costeffective.
Issuing a public notice in a local newspaper and sending a fact•h*et to p«rson« on the mailing li«t at the completion of the 30%design report. The purpose of the fact sheet and the publicnotice would be to inform the public of the technologies selectedthat %*er« proven effective during the treatability studiesconducted during the remedial design;
Backfilling the excavated area with common fill, vegetating thearea and the establishment of a suitable vegetative cover;
Operation and maintenance of landvault(s) for a minimum of thirtyyears; and
Institutional controls for land use and groundvater userestrictions.
STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the environment,complies with federal and state requirements that are legallyapplicable or relevant and appropriate, and is cost-effective. Thisremedy satisfies the preference for treatment that reduces toxicity,mobility, or volume as a principal element. Finally, it is determinedthat this remedy utilizes a permanent solution and alternativetreatment technology to the maximum extent practicable.
Because this remedy will result in hazardous substances remainingon-site at the areas addressed by operable unit four abovehealth-based levels, a review will be conducted within five yearsafter commencement of the remedial action to ensure that the remedycontinues to provide adequate protection of human health and theenvironment.
GREEK C. TIDWELL, REGIONAL ADMINISTRATOR DATE
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TABLE OP CONTENTS
1 . 0 Site Location and Description ..........1 . 1 Site History and Enforcement Activities
2 . 0 Highlights of Community Relations ............................ 7
3 . 0 Scope and Role of Operable Units ............................. 84 . o Summary of Site Characteristics .............................. 9
4.1 Geology/Soils ........................................... 94.2 Hydrogeology. .......................................... 104 . 3 Surface Water .......................................... 124.4 Sample Results Prom Former Waste Management Area 8..... 12
9.4 Utilization of Permanent Solutions to the MaximumExtent Practicable.....................................55
9 .5 Preference for Treatment as a Principal Element............. 56
10.0 Documentation of Significant Changes........................ 56
Appendix A - Responsivenose SummaryAppendix B - Concurrence Letters
-iii-
LIST OF TABLES
Table 4-1 Chemical of Potential Concern in Study-Wide Soils........ 14Table 4-2 Chemicals Of Potential Concern in Area 8 Soil............ 15Table 5-2 Health Effects Criteria For Oral Exposure
To Chemicals Of Concern.................................. 21Table 5-3 Health Effects Criteria For Inhalation Exposure to
Chemicals Of Concern;.................................... 22Table 5-6 Groundwater Cleanup Levels Provided in OU fl.............26Table 5-7 Groundwater Cleanup Levels For
Deep Soil Treatment.Areas................................27Table 5-8 Direct Contact Soil Cleanup Levels....................... 28Table 5-9 Subsurface Soil Cleanup Levels
For Groundwater Protection...............................29Table 8-1 Treatment Standards For Soils At The Ciba-Geigy Site.....50
Figure 2 Site Locations............................................ 4Figure 3 Generalized Geologic Cross-Section.......................11
Figure 4 Projected Location of Where the Summers and PestanModels will be Applied................................... 19
Figure 5 Process Flow Chart for Treatment of ContaminatedSoils.................................................... 46
Figure 6 Deep Soil Remediation Flow Chart......................... 51
DecisionRecord of DecisionOperable Unit FOOTCiba-Geigy siteMclntosh, i
1.0 Site LOCATION AND DESCRIPTION
The Ciba-Geigy Corporation Hclntoeh facility ia located in southernWashington County, northeast of Mclntosh, Alabama, approximately 50miles north of Mobile, Alabama (Figure 1). The operating facility islocated at 31° 15 '00" north latitude and 87° 58' 00" west longitude.The operating facility, which encompasses approximately 2.4 squaremiles, is situated between the Southern Railroad right-of-way on thewest and extends nearly to the escarpment separating the uplandterrace from the floodplain of the Tombigbee River. The propertyboundaries extend beyond the railroad westward toward U.S. Highway 43.The northern edge of the property merges into an undeveloped pineforest. To the south the property is bounded by an Olin Corporationfacility which has also been identified as a Superfund Site. Thesoutheastern portion of the property extends to the banks of theTombigbee River.
The facility is located in an industrial setting. The Ciba-GeigySuperfund Site ("Site") is contiguous with the facility boundary. TheAreas of Contamination (AOCs) addressed by CERCLA are located on theMclntoah facility due east of the current production area. The AOCsare roughly divided by the river water reservoir (see Figure 2). Area8, which is addressed by this ROD, is located in the southern half ofthe AOC to the east of the reservoir. The nearest population centeris the town of Mclntosh, which is located approximately two miles tothe southwest.
1.1 Site HISTORY AND ENFORCEMENT ACTIVITIES
The Ciba-Geigy Mclntosh facility, formerly owned by Geigy ChemicalCorporation, began operations in October 1952, with the manufacture ofone product, dichlorodiphenyl-trichloroethane (DOT). Through 1970,Geigy expanded its Mclntosh facilities by adding the production offluorescent brighteners used in laundry products; herbicides;insecticides; agricultural chelating agents; and sequestering agentsfor industry.
•WASHINGTON CCUNTY.ALABAMA :
In 1970, Geigy »«rged with Ciba (Chemical industry in Basel,Switzerland), forming the Ciba-Geigy Corporation. Since thenCiba-Geigy ha« continued to expand its operations with the addedproduction of resins and additives used in the plastics industry,anti-oxidants, and small-volume specialty chemical products (i.e.water treatment chemicals and fire fighting foams). The presentfacility occupies approximately 1,500 acres and employs about 1,200workers.
The BPA Region IV Environmental Services Division of Athens, Georgia(BSD) conducted an investigation in August 1982 of the Olin ChemicalCompany located adjacent to the Ciba-Geigy Site. As a part of theinvestigation, BSD sampled a drinking water well on Ciba-Geigyproperty. This sampling indicated the presence of hazardoussubstances which warranted further evaluation of the contaminationproblem at Ciba-Geigy. In June 1983, the Hazardous Ranking System(HRS) survey was completed and the Site was assigned a ranking of53.42. The Ciba-Geigy Mclntosh Plant was Included on the NationalPriorities List (NPL) in September 1983.
In October 1985, BPA issued Ciba-Geigy a RCRA permit, which included acorrective action plan requiring Ciba-Geigy to remove and treatcontaminated groundwater and surface water at the site. Thecorrective action plan stipulated that Ciba-Geigy would prepare aRemedial Investigation/Feasibility Study (RI/FS) for the disposalareas being studied by the Superfund program. Figure 2 depicts thelocation of CERCLA areas within the Ciba-Geigy Site.
The ten units closed under the RCRA permit includeiDiazinon Wastewater Seven Utilized to pipe Diazinon waste tothe Diazinon Destruct Impoundment. Closure under postclosure care in 1976.Triangular Impoundmenti Constructed in the 1970s to decomposeDiazinon residues. Closure during interim status completedin 1986.Rectangular Impoundments Constructed in 1972-1973 to holdsludge from the dilute impoundment. Closure during interimstatus completed in 1987.Class C Landfill i Permitted by Alabama in 1973 and permittedunder RCRA Interim Status regulations. Closure duringinterim status completed in 1987. .
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Biological Sludge Landfill* Permitted by Alabama in 1978 andlater operated under RCRA Interim Status for disposal ofde-watered sludge. Closure during interim status completed in1987«
Diasinon Destruct Impoundment! Constructed in 1965. Closureunder post closure care completed in 1989.
GM-44 Impoundmenti Put into service in early 1970s.Constructed for the GK-44 wastes high in nitrogen compounds.Its use was discontinued in the late 1970s. Closure underpost closure care completed in 1989.
Effluent Diffuser Linei Constructed in late 1968 to conveyeffluent for discharge into the Tombigbee River. Taken outof service in 1973 due to a change in the wastewatertreatment system, closure of RCRA impoundments, and a changein the NPOES permit.
Effluent Disposal Welli Installed in 1971. Used for theinjection of biotreated effluent to reduce the quantity ofNaCl discharged into the river. The use of the well wasunsuccessful and it was plugged in 1983. ADEM required nopost-closure monitoring.
Dilute Ditchi This ditch collected dilute wastewater andsurface water runoff to be conveyed to the DiluteImpoundment. Use ceased in 1971. Continued monitoring ofthis ditch under a RCRA Corrective Action permit.
Pursuant to the Corrective Action portion of the permit, in 1987/Ciba-Geigy installed a groundwater pumping system to intercept andremove contaminated groundwater from the shallow alluvial aquifer.The water removed from these wells was treated in the plant's existingon-site wastewater treatment system until fall 1988, when the plant'snew biological wastewater treatment system was completed and used totreat the groundwater. The treated water is discharged into theTombigbee River in compliance with appropriate National PollutantDischarge Elimination System (NPDES) Regulations.Ciba-Geigy has installed four (4) corrective action monitoring wellsalong the southern boundary of the property to monitor theeffectiveness of the pumping well system. The effectiveness of thepump and treat system in preventing the migration of contaminatedgroundwater off-site and reducing the concentrations of contaminantsin the groundwater is well established.
BPA cos leted the Superfund decision document (the Record of Decisionor ROD) for operable unit one in September 1989 after public commentsvere carefully considered. The ROD identified the BPA selectedremedy, 'Ho Further Action-. This selection was based on theestablished effectiveness of the groundwater pump and treat systemalready installed under the RCRA permit to address groundwatercontamination in the shallow aquifer at the Site.
In accordance with the corrective action plan, Ciba-Geigy retainedBCM, a technical consultant, to perform the RI/PS. Pield work, whichbegan in October 1985, was conducted by BCM on Ciba's behalf, withBPA's oversight. The principal finding of the Ri study was thedefinition of the extent of contamination from eleven additional wastemanagement areas within the study area that will be addressed underCERCLA.
The CERCLA Site has been grouped and divided into two Areas ofContamination (AOC) based on their relative proximity to each other.The AOCs are roughly separated by the reservoir (See Figure 2).
In January 1990, Ciba-Geigy submitted the PS report. This reportidentified and screened alternatives for cleanup at the eleven formerwaste management areas. In September 1991, BPA issued a RODaddressing soil contamination at 10 of eleven 11 former wastemanagement areas, (OU2), at the Site.
The major components of the selected remedy for 002 include:
Excavation of contaminated soils and sludges until establishedcleanup levels are reached or until site specific excavationlimits are reached.On-site thermal treatment of approximately 65,000 cubic yardsof highly contaminated soils and sludge;
Solidification/stabilization or the utilization of aninnovative technology proven effective during the remedialdesign, of approximately 62,300 cubic yards of moderatelycontaminated soils and sludge;
Disposal of treated toil and residual ash from the thermaltreatment process in an on-site RCRA Minimum TechnologySubtitle C landvault(s);
In-«itu soil flushing combined with itolation walli and extraction**Ul KJS*?1!** ***" where the rl8k ba««d cleanup levels arenot achieved before, excavation depth of 20 feet is reached.Innovative technologies (in-situ vacuum extraction or in-situbiorenediation) nay also be used in addition to or instead ofin-situ soil flushing, if during the remedial design eithertechnology is found to be effective in reducing contaminantconcentrations in the soil and is cost effective.
Issuing a public notice in a local newspaper and sending a factsheet to persons on the mailing list at the completion of the 30%design report. The purpose of the fact sheet and the publicnotice would be to inform the public of the technologies selectedthat were proven effective during the treatability studiesconducted during the remedial design;
Backfilling the excavated areas with common fill and vegetatingthe area and the establishment of a suitable vegetative cover,
Operation and maintenance of landvault(s) for a minimum of thirtyyears; and
Institutional controls for land use and groundwater use.EPA will continue its CERCLA enforcement activities and will notifyCiba-Geigy prior to the initiation of the remedial design forparticipation in the selected remedial action. Should Ciba-Geigydecline to conduct future remedial activities, EPA will either takeadditional CERCLA enforcement actions or provide funding for theseactivities while seeking cost recovery for all EPA-funded responseactions at this Site.
2.0 HIGHLIGHTS OF COMMUNITY RELATIONS
The RI for the Ciba-Geigy Site was released to the public inAugust 1988. The FS and the Proposed Plan for the Ciba-GeigySite addressing Operable Unit 2, were released to the public onJuly 30, 1990. An addendum to the FS addressing thecontamination in Area 8 (OUt4), was released to the public inApril 1992. The Proposed Plan addressing=OU#4 was released tothe public on April 30, 1992. These documents were madeavailable by placement in both the administrative record docketand the information repository maintained at the EPA docket roomat Region IV Headquarters in Atlanta, Georgia and at the HclntoshTown Hall, la Mclntosh, Alabama. Pursuant to regulations, apublic comment period was held from April 30, 1992 throughMay 29, 1992. . '
A notice was placed in the Mobile Press Register on April 301992 announcing the cement period. In addition to the publiccomment period and the administrative record files, a publicmeeting was held on Hay 19, 1992 in Mclntosh Alabama. At thismeeting representatives from EPA answered questions and addressedcommunity concerns. * u«teo»ea
A response to all significant comments received during the publiccomment periods is included in the Responsiveness Summary(Appendix A), which is a part of this Record of Decieion.
This decision document presents the selected remedial action foroperable unit four of the Ciba-Geigy Site, chosen in accordancewith CERCLA, as amended by SARA and to the maximum extentpracticable, the NCP. The decision for this Site is based on theadministrative record. The requirements under Section 117 ofCERCLA/ SARA for public and state participation have been met forthis operable unit.
3.0 SCOPE AND ROLE OF QPEPABl-^ UNITS
Due to the size of the facility, the number of areas and the varietyof contaminants, the problems at the Ciba-Geigy Site are complex. Asa result EPA has organized the work into four (4) operable units .(OUs). The operable units at this Site as identified in the RODissued for Operable Unit Two in September 1991 are:00 *1 Contamination of the shallow (Alluvial) groundwater aquifer.
00 t2 Contamination of soils at ten of eleven former wastemanagement areas.
00 #3 Contamination within the floodplain, the effluent ditch(previously called the lower portion of the dilute ditch) andareas in the Tombigbee River within close proximity to theSite .
00 f4 Contamination of soils in former waste managementArea 8 and the dilute ditch (previously called the uplandportion of the dilute ditch) .
This Operable Unit (OO *4), addresses the contamination of soils atformer waste management area 8. The Dilute Ditch was closed inaccordance with an approved RCRA Closure Plan. The ditch, as well asother closed units, was excavated, capped and is being maintainedthrough RCRA Poet-Closure care. Upon further evaluation, EPA has
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decided to continue addressing the Dilute Ditch under RCRA authoritvae administered through the HSHA Permit. *'
The January 1990 Draft Feasibility Study Report and the February 1992addendua to the Feasibility study Report submitted by Ciba-Geigydocument the development, screening and detailed evaluation ofpotential alternatives for remediation of former waste management area8 identified and initially characterised during the RemedialInvestigation. BPA has evaluated the alternatives and the risk posedby the contaminants as they relate to the "CBRCLA" Site. Based onthis evaluation, BPA has determined the alternative or combination ofalternatives which will achieve the CBRCLA cleanup objective, toremediate the source of contamination and prevent current or futureexposure to contaminated groundwater at former waste management area8. Thia operable unit is consistent with past work conducted at theSite and future work to be conducted.
4.0 SUMMARY OF Site CHARACTERISTICS
4.1 GEOLOGY/SOILS
The Ciba-Geigy property is located within the Southern PineHills, which are elevated features that regionally slopesouthward toward the Gulf of Mexico. These hills are dissectedby various river systems that feed into the Gulf. The plant is 'located upon a low terrace adjacent to the Floodplain of theTombigbee River. The property lies within the boundaries of theMobile Graben, a downthrown fault block paralleling the river.
The surficial and shallow geology can be broken into threedistinct features. The uppermost layer is a relativelycontinuous clay layer containing sand and silty sand lenses andclay layers that range from only a few feet to over 50 feet inthickness. Underlying the clay layer are Pleistocene-agealluvium and low terrace deposits of interbedded gravel, silt,and clay with thicknesses ranging from 60 to 100 feet. Thesedeposits outcrop throughout the area.Underlying the low terrace deposits are alternating layers ofMiocene-age gravels, sands, and clays. Regionally, Upper Mioceneclay hydraulically separates the Miocene and Pleistocene deposits(See Figure 3).Erosion and redeposition of these sediments reflect dynamicdepositional environments which are common on a regional scale.This has resulted in a complex subsurface stratigraphy.
Variation* of physical characteristic* (e.g. porosity, grainoise, hydraulic conductivity) both vertically and laterallywithin the strata complicate the movement of water in thesubsurface.
Nine different soil series are located within the area'of theplant. These soils are generally loamy clays and sands thatrange from well drained to poorly drained. Permeability of thesoil ranges from moderate to low.
4.2 HYDRQGEOLQGY
Both the Pleistocene and Miocene strata are water bearing andrepresent two distinct aquifers, the Alluvial and Upper Miocene.They are separated by a number of shale and clay aquitards andaquicludes.
The Alluvial aquifer is composed of the recent and Pleistoceneterrace and alluvial deposits. The thickness of the aquifer andthe water level depend on the thickness and configuration of theoverlying clay layer. Under natural, semi-confined conditions,the saturated thickness of the-Alluvial aquifer ranges from lessthan 30 feet to over 50 feet. Recharge of the Alluvial aquifercomes locally, from rainfall, streams, and reservoirs. Highfloods in the river floodplain also recharge the aquifer.
The groundwater flow of the Alluvial aquifer normally slopesgently to the south-southeast toward the Tombigbee River.However, the flow of groundwater is modified by the pumping andcapture of contaminated groundwater by the plant and rechargefrom the Site reservoir. This system was designed to reduce thelevel of contaminants in the groundwater below the facility andprevent further migration of the contaminated groundwater. Theconcentrations of contaminants present in the groundwater hasdecreased and the operation of the intercept wells has reversedthe direction of groundwater flow as a result of the pumping.The Upper Miocene underlying the plant is a confined aquifer ofsands and gravels capped by a clay layer about 100 to 130 feet inthickness. Recharge of this aquifer is believed to come fromregional infiltration in outcrop areas up-dip to the north. Incontrast to the Alluvial aquifer, the quality of Upper Miocenewater can be effected by regional influences such as salt domesor saltwater intrusion from the Gulf of Mexico.
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Paleo-channeling has been found to exist in the surface of theMiocene clay. However, during the investigation for theGroundwater Corrective Action Program, and as a part of theRI/PS, it was determined that the two aquifers are nothydraulically connected.
4.3 SPRPACB WATER
The Ciba-Geigy facility property lies within the Tombigbee RiverBasin which has a drainage area of 8,378 square Biles. TheTombigbee River flows past the Site, converging further southwith the Alabama River to form the Mobile River.Surface water features at the Ciba-Geigy plant include thediverted Johnson Creek on the northern edge of the property, anda large, man-made reservoir, between the manufacturing area andthe waste management facilities. Surface water runoff on thenorthern, undeveloped corner of the property drains off-sitethrough ditches into the Tombigbee River. The surface watersystem south of Johnson Creek has undergone extensive change. Inaddition to a new wastewater treatment system, a new stormwatermanagement system has been constructed to replace the oldcombined dilute wastewater/stormwater system, which usedstormwater sewers, open surface ditches, and the dilute ditch toconvey mixed dilute wastewater and stormwater to the diluteimpoundment.
The new system segregates all wastewater, dilute and process/ tothe wastewater collection and transfer system and then on to thebiological wastewater treatment system. All stormwater sewershave been renovated and all open ditches have been replaced withstormwater sewers draining to stormwater retention tanks capableof holding a one-inch rainfall over the entire developedmanufacturing area of the plant. All initial rainwater retainedis transferred to the biological wastewater treatment plant. Allstormwater overflow (rainfall above one inch) is diverted toestablished drainagewaya discharging to the Tombigbee River.
The primary essphasia for analytical testing during the RI was todetermine the nature and extent of the soil contamination at theSite. AB a result, soil and waste samples were collected andanalysed to determine the chemical contamination present at the
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Site. Th« following i§ a brief description and a voluae estimateof former waste aanageaent area 8 to be addressed in operableunit fouri under CBRCLA. authority.
Table 4-1 su««arites the maximum, and minimum concentration* anddetection frequency for the contaminant* found in the soilthroughout the Site.
During the development of this ROD it was determined, based ontoxicity, mobility, and frequency of detection, that if certaincontaminants were excavated and remediated to acceptable levels,the remaining contaminants would also be excavated and remediatedto acceptable levels. The selected contaminants of concern forarea 8 are presented in Table 4-2 (also see section 5.1).
e a
Area 8 is located along a bluffline constructed by the UnitedStates Corps of Engineers and is currently grassed with thebluffline escarpment stabilised with rip-rap to minimize soilerosion. The bluffline contains massive quantities of non-chemical construction/demolition rubble such as concretefragments (some very large), piles of crushed concrete, bricks,stone fiberglass, asbestos, metal debris and alternate layers ofresidues from open burning, all covered with clay fill. Theestimated volume of contamination in Area 8 is 128,000 cubicyards .
5.0 SUMMARY OF Site RISKS
CERCLA directs the Agency to conduct a baseline risk assessmentto determine whether a Super fund Site poses a current orpotential threat to human health and the environment in theabsence of any remedial action. The baseline risk assessmentprovides the basis for determining whether or not remedial actionis necessary and the justification for performing remedialaction.
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TABLE 4-2CHCmCAU Of POTHTIAl CO*CIM II UTI 8 MIL
Geometric Man *»nmMCanetoirjtion Concentration Detection
The majority of the wastes and residues generated by productionoperations at the facility hav« been managed, treated; anddisposed of on-site throughout the Site's history. The wastedisposed of in Area 8 are covered with 4-8 feet of fill materialand sod. There is no evidence of contaminated surface materialin this area. Therefore, the media of concern is subsurfacesoil. The classes of chemicals measured in the variousenvironmental media in the Remedial Investigation were evaluatedfor inclusion as chemicals of potential concern in the riskassessment by application of screening criteria.
The criteria which resulted in elimination of chemicals included:Site contaminant concentrations below background concentrations;measurements below quantitation limits; a combination of lowtoxlcity and low concentration or low persistence and lowconcentration and low frequency of detection.
The chemicals of concern for the Site include high molecularweight chlorinated pesticides (SHC isomers), Site-manufacturedpesticides ( atrazine, diazinon, prometryn, siAazine), volatilesolvents ( chloroform, toluene, xylenes) and metals (copper,lead, arsenic, chromium and an iron slurry waste). The media of.,concern for this operable unit is contaminated subsurface soil.The maximum and minimum concentrations of analytes found in thesubsurface soil throughout the Ciba-Geigy Site are contained inTable 4-1.
The geometric mean and maximum concentrations for the chemicalsof potential concern in Area 8 are summarized in Table 4-2.
5.2 EXPOSURE ASSESSMENT
Whether a chemical is actually a concern to human health and theenvironment depends upon the likelihood of exposure, i.e. whetherthe exposure pathway is currently complete or could be completein the future. A complete exposure pathway (a sequence of eventsleading to contact with a chemical) is defined by the followingfour elementss
* A source and mechanism of release from the source,* A transport medium (e.g., surface water, air) and
mechanisms of migration through the medium,* Ths) presence or potential presence of a receptor at the
exposure point., and '•'
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A rout* of exposure (ingestion, inhalation, dermalabsorption).
If all four elements are present, the pathway i« consideredcomplete.
An evaluation was undertaken of all potential exposure pathwayswhich could connect chemical sources at the Site with potentialreceptors. All possible pathways were first hypothesized andevaluated for completeness using EPA's criteria. Three currentpotentially complete exposure pathways and one future exposurepathways remained after screening. The current pathwaysrepresent exposure pathways which could exist under current Siteconditions while the future pathway represents exposure pathwayswhich could exist, in the future, if the current exposureconditions change. The current exposure pathways were developedfor the Ciba-Geigy Areawide Risk Assessment. Since there is noknown surficial contamination in Area 8 it is unlikely that thepathways are complete for this Area. Exposure by each of thesepathways was mathematically modeled using generally conservativeassumptions.
The current pathway* aret" inhalation by nearby residents of contaminated dust
particles;" inhalation by nearby residents of volatile chemicals
from subsurface sources in the past waste managementarea; and
" ingestion of venison by local hunters from deer feedingin vegetated areas of the impacted area.
The future pathway isi* ingestion of contaminated groundwater.
The exposure point concentrations for each of the chemicals ofconcern and the exposure assumptions for each pathway were usedto estimate the chronic daily intakes for the potentiallycomplete pathways, with the exception of the groundwater pathway.The chronic daily intakes were then used in conjunction withcancer potency factors and none arc inogenic reference doses toevaluate risk.
17
The groundwater at the Ciba-Geigy Site currently contain*concentration* of the Site contaminant* at levels which wouldpose an unacceptable risk to human health if the water was beingused for human consumption. However, the surficial aquifer is nolonger being used as a source of potable water at the Ciba-Geigyplant. Also the ongoing groundwater extraction and treatmentsystem is capturing the contaminated groundwater. AS a result,this is not a current complete exposure pathway. The formerwaste management area 8 is a contributor to the contaminatedgroundwater.
The future groundwater exposure pathway was evaluated bycomparing soil concentrations with health-based soil cleanuplevels. The health-based soil cleanup levels were calculatedusing groundwater models, to assure that drinking water maximumcontaminant levels (MCLs), as established under the Safe DrinkingWater Act or health-based levels would not be exceeded in thegroundwater as a result of contaminants leaching through thesoil. As with all models, certain assumptions apply. At theCiba-Geigy Site, some of the wastes extend to or near thegroundwater surface while other areas have a significant amountof uncontamlnated clay beneath £he waste. As a result, twomodels have been applied to the areas of contamination. The BPAhealth-baaed subsurface soil cleanup levels are based on eitherthe Pestan or Summers models, which are used to estimategroundwater contaminant concentrations resulting from migrationof contaminants through the soil column. The Pestan and SummersModels incorporate Site-specific aquifer characteristics andchemical-specific soil-water partition coefficients.
The Pestan model would be used in portions of area 8 where Ciba-Geigy can demonstrate to EPA's satisfaction that anuncontaminated zone exists between the contaminated soil and thegroundwater surface (See Figure 4 for an estimate of the portionof Area 8 where the models will be applied). The Summers modelwould be used in areas where contamination has extended to or isnear the groundwater surface.The major assumptions about exposure frequency and duration thatwere included in the exposure assessment were*
* For the ingestlon of venison scenario, it was assumedthat a local hunter kills one deer per year and that thevenison yield from the deer is 44 kg. This quantity ofvenison was conservatively assumed to be consumedannually throughout a 70-year lifetime.
18
B 3 7 + B 7 2 + 0 D 2 3 *
1NORTH
B l l
B10 +
one
I0scale
100feet
200
• soil sample location meetingcriterion for Summers model
+ soil contamination near watertable
* deepest soil sample showscontamination
o soil sample location not meetingcriterlotPlor Summers model
—— boundary of Site 8— — area considered for the Summers
model
LEGEND
For the inhalation of ambient air scenario it wasassumed that an individual live* in the nearestresidence (2.5 km from the Site) and inhales 20 mj ofai* P« day over a 70-year lifetime. All particulatematter at the exposure point was assumed to berespirable and delivered to the pulmonary region of thelung. The chemicals of concern ware assumed to be 100percent bioavailable.
In all scenarios a standard body weight of 70 kg wasused.
5.3 TQXICITY ASSESSMEKT
Toxicity values are used in conjunction with the results of theexposure assessment to characterize Site risk. EPA has developedcritical toxicity values for carcinogens and noncarcinogens.Cancer potency factors (CPFs) have been developed by EPA'sCarcinogenic Assessment Group for estimating excess lifetimecancer risks associated with exposure to potentially carcinogenicchemicals. CPFs, which are expressed in units of (mg/kg/day)'1,are multiplied by the estimated intake of a potential carcinogen*in mg/kg/day, to provide an upper-bound estimate of the excesslifetime cancer risk associated with exposure at that intakelevel. The term "upper bound" reflects the conservative estimateof the risks calculated from the CPF. Use of this conservativeapproach makes underestimation of the actual cancer risk highlyunlikely. Cancer potency factors are derived from the results ofhuman epidemiological studies or chronic animal bioassays towhich animal-to-human extrapolation and uncertainty factors havebeen applied. The CPFs for oral ingestion and inhalationexposure to the contaminants of concern for the areawide studyare contained in Tables 5-2, and 5-3 respectively.
Reference doses (RfDs) have been developed by EPA for indicatingthe potential for adverse health effects from exposure tochemicals exhibiting nonearcinogenic effects. RfDs, which areexpressed in units of mg/kg/day, are estimates of lifetime dailyexposure levels for humans, including sensitive individuals.Estimated intakes of chemicals from environmental media can becompared to the RfD. RfDs are derived from human epidemiologicalstudies or animal studies to which uncertainty factors have beenapplied (e.g./ to account for the use of animal data, to predicteffects on humans). These uncertainty factors help insure that
(a) uncertainty fa*ter« uo«d to develop reference doses consist of Multiples of 10, eacn factor representing *specific aroaa>f uncertainty inherent in the data available. The standard uncertainty factors include:
. A 10-fo4e9actor to account for the variation in sensitivity aaong tne M*t»rs of tne nuMn popui«tion;
. A KMata) foctor to account for the uncertainty in ostrapoiatina animal data to me ea»« ot n«»en*;
. A 10-fatd factor to account for uncertainty in o*trapoiatina fro* IMS tnan cnronic MACls to cnronicMM It and; .'
. A 10-feid factor to account for the uncertainty in eitrapelettne fraa tOiCis to aOMLs.(b) Source of Reference DOOM: HIS • cftoaical file* of the Intefratod lisk information Svstoa; KiC • »an»*
Contaainaiu Level Cool; «€A • Noolth Iffoct* Assssieant; M • Health Advisory; MS • national Acaoe«y otScience; OBW. • Oak Ridfe National Mboratorie*.
' studiee and adequate evidanco frea oniaai studies; C*-*oa«ible »ua«n Carcinaaan, naiied evidence mm the abeerce of nuaan data; O'-aot Clauiflod aa to huaan earcinooanicity; and (••evidence ofMoncarcinaaenicity. _ _ .
(d) Acceptaoie daily intake derived by Ciba-Ceify froa the remits of uneuolisned studies performed oy en
• • Review pending.•• • Citra Mfety factor of 10 MO applied ta account for possible carcinofcnicity (verbal caam^ication
••• • Ne«itn -no rnvironaental Iffects »reflle (*!•> 1»8* and veroal coamneation • See —'—»- 10"*
•BIBLE 5-3CMICTS OITIIU f« lUUUAnOi fUOSJtf 10 OKMICAtS Of COM3U
(a) uncertainty fo*oort-usod to dtvolo* reference doses consist of oultiples of 10. eaen factor representing < i p e c < r < carea of uncertainty inherent In tne data availaeie. The standard uncertainty factors include:
. A 10-fold ffcttor to account for tne variation in sensitivity aaons tne oeoBers of tnefetter
. A I0*fol« 9Mar to account for tne uwertainty in extrapoiatine. aniMl data to tne ease of
. A 10-fold fitter to accost for uvertainty in axtrapoiatinf froti less than chronic •QAit* to cnronic »OAtt»;and; -".-•'• •
. A 10-fold factor to accowtt for the uncertainty in ejitrapolatinf froa kOAIks to NOAfis.(b) Source of •eferonce Ooaoti HU' • MoltM effects AssessMnt; "UA04 • Notional :«o»iont Air Quality Staroaro.
we lent of evidence classification scftej* for care instant; A--Hu«en Carc«no«on. sufficient evidence fro» nu»«oepido*iole«ical studies; 11-proMfele auvn Careinooen, liaitod evidence fret) OBidMioioaicai studies and aoeguaevidence fro« enieai studioo; §a--f>roBe»le MuMn Carcinooon. Inadequate evidence from epidaaneioficai »'-»'•» •"adequate evidence fro* anieal studios; C--f>oasiole HVOW Corcinofen, Uoited evidence in anieou in tne to»«nc«huvan data: 0--eot Classified at to hu»an corcinooonicity; and l--lvidonee of •oneareinooenicitv.
tt
• • teviev psndinf.•0 • eot determined
the RfDa will not underestimate the potential for adversenoncarcinogenic effect* to occur. The RfDs for oral ingestionand inhalation exposure to the contaminant* of concern for theareavide study are contained in Table 5-2, and 5-3 respectively.
5.4 RISK
Human health risks are characterised for potential carcinogenicand noncarcinogenic effects by combining exposure and toxic ityinformation. Excessive lifetime cancer risks are determined bymultiplying the estimated daily intake level with the cancerpotency factor. These rishs are probabilities that are generallyexpressed in scientific notation (e.g., IxlO"4), An excesslifetime cancer risk of lxlO~* indicates that, as a plausibleupper bound, an individual has a one in one million additional(above their normal risk) chance of developing cancer as a resultof site-related exposure to a carcinogen over a 70-year lifetimeunder the assumed specific exposure conditions at a Site.
The Agency considers individual excess cancer risks in the rangeof IxlO-4 to IxlO"* as protective-; however the IxlO*4 risk level isgenerally used as the point of departure for setting cleanuplevels at Superfund sites. The point of departure risk level ofIxlO*4 expresses EPA's preference for remedial actions thatresult in risks at the more protective end of the risk range.
Potential concern for noncarcinogenic effects of a singlecontaminant in a single medium is expressed as the hazardquotient (HQ) (or the ratio of the estimated intake derived fromthe contaminant concentration in a given medium to thecontaminants's reference dose). A HQ which exceeds one (1)indicates that the daily intake from a scenario exceeds thechemical's reference dose. By adding the HQs for allcontaminants within a medium or across all media to which a givenpopulation may reasonably be exposed, the Hazard Index (HI) canbe generated. The HI provides a useful reference point forgauging the potential significance of multiple contaminantexposures within a single medium or across, media. An HI whichexceeds unity indicates that there may be a concern for potentialhealth effects resulting from the cumulative exposure to multiplecontaminants within a single medium or across media.The health risks resulting from exposure to the current pathwaysare as follow* s the upper bound excess lifetime cancer riskassociated with inhalation of airborne particulate matter wasixlO"*; the cancer risk associated with inhalation of
23
volatilised chesUcals from the combined source areas was 3x10-"•and the cancer risk associated with ingestion of venison was2xlO-10. Hone of the non-carcinogenic chemicals of potentialconcern exceeded a hazard quotient of one (1).
The future pathway based on groundvater contamination resultingfrom leaching of contaminants from the soil was evaluated bycomparing the health-based soil cleanup levels and the soilconcentration of the contaminants of concern in the former wastemanagement area 8. Table 5-9 contains this comparison. The soilcleanup levels represent the residual soil concentrations thatwould not cause Federally regulated drinking water standards tobe exceeded as a result of contaminants leaching through thesoils to the groundwater.
The soil excavation levels for the carcinogenic contaminant ofconcern (gamma-BHC) is based on the Federal maximum contaminantlevel (MCL). The model-calculated soil remediation levels fornoncarcinogenic contaminants of concern reflect the proposed MCLfor simazine and a hazard quotient (HQ) of one (a concentrationthat will not exceed the chemical-specific acceptable dailyintake or reference dose) for the other noncarcinogenicchemicals. In addition this number is reduced to allow for thegroundwater to provide only 20% of the acceptable daily intake.The comparison of the health-based cleanup level concentrationsfor the protection of groundwater with the actual soilconcentrations indicate that the soils in the former wastemanagement area 8, contain concentrations of Site-relatedcontaminants which exceed the health-protective soil levels.
»
The potential current exposure pathways are not producing anunacceptable level of risk and consequently will not drive theremediation of the former waste management areas. However, sincethe subsurface soils are either currently contributing or couldpotentially contribute in the future to unacceptable levels ofgroundwater contamination, this pathway will dictate theremediation of the contaminated subsurface soils. Although thesurface soil is not currently well characterized/ the directcontact pathway could potentially require the remediation ofsome surface soils.
5.5 ENVIRONMENTAL RISK
The source area is presently covered with fill and therefore isnot easily accessible to certain terrestrial species. For thisreason the source areas.are not expected to have toxic effects on
24
thos« terrestrial aniaals at this time. However, the ecologicalassessment indicate! that the Site may have toxic effect* oncertain plant • pec lee, as veil as robins and shrews in the areasof concern in the future. The selected remedy based onprotection of human health will eliminate the potential for suchtoxic effects since the environmental exposure pathways will notexist. The environmental impact for the bottom dwelling aquaticcommunities in Johnson Creek, the floodplain, and the TombigbeeRiver will be further evaluated in Operable Unit #3.
5.6 CLEANUP
The September 1989 ROD for Operable Unit #1, GroundwaterRemediation, addresses the contaminated groundwatcr exposurepathway. The cleanup levels of the currently operatinggroundwater pump and treat system which are applied at the Siteboundary ensures that concentrations of contaminants in thegroundwater do not exceed Maximum Contaminant Levels (MCLs) orMinimum Detection Levels (MDLs) for any future consumers of thiswater are contained in Table 5-6. The cleanup levels forgroundwater in deep soil treatment areas are contained in Table5-7. The groundwater cleanup levels in the deep soil treatmentareas have been generated to ensure localized isolation andtreatment of contaminated groundwater near Area 8. These levelsare either the Federal MCLs or 1 xlO"4 health basedconcentrations which were used to determine the soil excavationlevels. All cleanup levels applied at this Site are within EPA'sacceptable 1 x 10'4 to 1 x 10'* risk range. The 1x10'' risk level,MCL or MDL was used to calculate acceptable concentrations ofcontaminants at the Site boundary and for ingest ion andinhalation. Subsurface soil and its surrounding groundwatercleanup levels are applied at the 1 x 10'4 risk level since thisis an industrial site and in this case it would be more costeffective to let any residual contamination be captured by thecurrently operating groundwater pump and treatment system. Thisis consistent with areas in Operable Unit *2 requiring nolocalized deep soil treatment. Groundwater extracted in the soilflushing portion of the remediation will be treated by theexisting pump and treat system.
The ROD for Operable Unit #1 did not address the sources ofcontamination. Addressing the contamination source will decreasethe time required to pump and treat. Cleanup levels for thecontamination source (the subsurface soils) for groundwaterprotection are based on the Federal MCL for the carcinogen
25
(gamma-BBC) and a hatard quotient of 1 for noncarcinogens. Thiscleanup Isnrel provides an acceptable exposure level that isprotective of human health. Although there is no evidence thatsurface soils are contaminated in this area/ cleanup levels areprovided which should be achieved in the top 12 inches of soil.Cleanup levels for contaminated surface soil are based on aworker exposure scenario and assume a commercial/industrial landuse. These levels are based on the ingestion and inhalationexposure routes and represent a IxlO"* risk level for carcinogensand a hazard quotient of 1 for noncarcinogens. The clennuplevels for direct contact of surface soils are listed in Table5-8.
The following groundwater cleanup levels are being applied at theproperty boundary for groundwater leaving the Site to ensure thatany future groundwater consumers will not be exposed tounacceptable concentrations of Site-related chemicals in thegroundwater. The concentrations presented represent either theregulated Maximum Contaminant Level (MCL) or the MinimumDetection Level for the constituents listed.
TABLE 5-6
GROUMDNATBR CLEANUP LEVELSAS PROVIDED IN ROD ADDRESSING 00*1
Por the in-»itu remediation processes, the following groundwatercleanup level* would be applied to any groundwater withdrawal well*installed within the RCRA defined point of compliance or within thearea* identified during the Remedial Action. The withdrawal wellewould be installed in areas where subsurface soil cleanup levels werenot achieved before excavation limits were reached.
TABLE 5-7(IxlO-4 Risk Corresponds)
GRODNDNATKR CLEANUP LEVELS POR DEEP SOIL TREATMENT AREAS
Compound CleanupLevel (ug/1)
a l p h a - B H C 6 7 6beta-BHC 2.0Lindane 0.2delta-BHC . 0.2DOT ' 10.0DDD 10.0DDE 10.0Diazinon 6.0Chlorobenzilate 140.0Ametryn 630.0Bladex 14.0Simazine 1.0Atrazine 3.0Prometryn 28.0
27
CIBL* 3-8SOIL CXJtAHUP LSVSLS FOR OQf 4
AT TB1 CIBJMaiQY Sit*
The following table provides the direct contact cleanup levels.These levels will be applied to the top 12 inches of soilthroughout the area of contamination. The cleanup level forgamma-BHC represents a 10"* risk level. The cleanup levels forthe remaining chemicals represent an HQ of one (1).
* These chemicals are not considered to be carcinogens.Therefore, the cleanup levels do not represent a carcinogenicrisk level.
The cleanup levels for gamma-BHC and simazine in the followingtable are soil levels derived to achieve based on the MCL andproposed MCL, respectively in the groundwater. The cleanuplevels for the remaining chemicals represent a concentrationwhich, when combined with the Site specific exposure assumptions,will yield a daily intake which does not exceed the chemical'sreference dose (RfD). The RfD is an estimate of the lifetimedaily exposure level for humans, including sensitive individuals,which will not produce adverse health effects. In addition therisk based concentration has been reduced to allow groundwater toprovide only 20% of the acceptable daily intake.
* These chemicals are not considered to be a carcinogens. Therefore, thecleanup levels do not represent a carcinogenic risk level.
Although the contaminants of concern are not the only contaminants atthe Site, they were chosen based on toxicity, mobility and frequencyof detection throughout the Site. It is anticipated that contaminantsat the Site which do not have cleanup levels presented in this RODwill be reduced to acceptable levels when cleanup levels are met forthe most toxic and most mobile contaminants for which cleanup levelshave been established.
The groundwater at the Ciba-Geigy Site currently containsconcentrations of Site-related contaminants at levels which would posean unacceptable risk (cumulative risk in excess of 1x10"*) to humanhealth if the water was being used for human consumption. Actual orthreatened releases of hazardous substances from this Site, if notaddressed by implementing the response action selected in this ROD,may present an imminent and substantial endangerment to public health,welfare/ or the environment.
6.0 DESCRIPTION OF ALTERNATIVES
Eleven alternatives for remediation of contaminated soils at Area 8 ofthe Ciba-Geigy Site were evaluated in the Feasibility Study Report.After reviewing comments received during the initial comment periodfor OU#2, the concept! of the eleven alternatives were reduced to fouralternatives based on the similarities in their technologies.
29
6.1 yt*«MATIVE IK). 1 - Me fr n
The no action alternative is carried through the screening process asrequired by tb« Rational Oil and Hazardous Substance* PollutionContingency Plan (NCP). This alternative is used as a baseline forcomparison with other alternatives that are developed. Onder thisalternative, BPA would take no further action to minimize the impactsoil contamination would have on the groundvater. Contaminants in thesoil would continue to leach into the groundwater at levels whichwould exceed groundwater protection standards. The overall remedialaction levels would not be achieved within 100 years by utilizing thisalternative. There is no cost associated with this alternative sinceno additional activities would be conducted.
6.2 ALTERNATIVE NO. 2 - Containment
This alternative consists of placing a soil bentonite slurry vailaround the perimeter of the area to prevent lateral migration ofcontaminants in the groundwater. A multilayered RCRA cap would beplaced over the area to minimize the vertical migration of soil con-tamination. Solidification/stabilization may be required in oneportion of the Site containing soft waste to increase the strength ofthe waste to sufficient levels to support a cap system. The areawould be revegetated following construction activities. Soilcontamination would not be reduced, but isolated from the environmentby the cap and slurry wall. Institutional controls (land andgroundwater use restrictions) would be necessary to ensure theintegrity of the alternative. Following the construction of the capand slurry wall, the Site would be monitored to verify theeffectiveness of the remedy. The overall remedial cleanup levels asdefined in operable unit one, would not be achieved within 100 yearsby utilizing this alternative. The alternative could be constructedin 10 months. The present worth cost of this alternative, includingoperation and maintenance, is estimated to be $10,909,000.
Elements Common to Alternatives 3 and 4The remaining two alternatives involve the excavation of soil whichexceeds health-based cleanup levels. Although the actual excavationlevel* are not Applicable or Relevant and Appropriate Requirements(ARARs), they v*re established, in part, to ensure that the Federallyregulated drinking water standards (ie., Maximum Contaminant Levels),which are ARARS, are not exceeded by contaminants leaching from thesoils into the groundwater. Excavation would be conducted usingconventional methods. Excavations may be terminated before cleanup
30
levels ex* reached for any of the following situations (excavationlimits for this Site). -non
1. When large concrete structures are encountered such as buildingfoundations, reinforced concrete slabs and concrete roadway sectionsconnected with reinforcing steel, which require different types ofmaterials handling and excavation methods;
2. When the water table is encountered. This means that soilremoval methodologies would change and further pretreatment would berequired for the thermal treatment process of those soils. Dependingon the volume of soils removed from below the water table, there couldbe an adverse effect on the existing pump and treatment system.
3. When a depth of 20 feet is reached. Below this depth, excavationposes additional hazards to workers requiring different OSHA standardsand increasing the cost of excavations.
4. When the iron slurry waste is encountered. This material will betreated by in-situ stabilization/fixation. Cost effectiveness andimplementability were considerations in the decision(s) to haltexcavation.The four situations above have been defined as excavation limits.
6.3 ALTERNATIVE NO. 3 - Removal. Solidification/stabilization.and On—Site Disposal
This alternative consists of the excavation of contaminated soil andsludge within the Site until the established cleanup levels orexcavation limits are reached (see section 6.2, Elements Common toAlternatives 3 and 4). The excavated material would besolidified/stabilized.
After solidification/stabilization, the material would be disposed ofin an on-site landvault after RCRA LDR treatment standards, pursuantto a treatability variance, are met. In accordance with Super fundLand Disposal Restriction (LDR) Guidance #6A, for herbicides, whichare similar and are applicable to Site contaminants, a treatabilityvariance requires that the selected technology must demonstrate a90-99.9 percent reduction in the contaminants of concern.Uncertainty exists regarding the effectiveness ofsolidification/stabilization of material contaminated with elevatedconcentrations of organic contaminants. Therefore, treatabilitystudies would be conducted to determine the effectiveness of this
31
alternative) i» •••ting the legislated treatment standards.Solidification/it4bili«ation would be utilized for toil, where it 1§F*0!*?/ *0?1!!. 1^1161119 th€ cont*«inated foil concentrationa toLand Disposal M«trictions (LDRs) treatability variance levels. Thisarea A1" eo***£?* •* }*°n slurry waste that is completely unsuitablefor pugmill «t«biUzation. This waste would be treated by theutilisation of. an in-situ fixation process which would achieve theleachate requirements of LDR. The NCP establishes a presumption thattreatment to the legislated standards based on the Best DemonstratedAvailable Technology is generally inappropriate for CBRCLAcontaminated soil and debris (55 PR 8758-62, (March 8, 1990)).Therefore, compliance with the land disposal treatment standards wouldbe achieved pursuant to a treatability variance for CERCLAcontaminated soil and debris. This treatability variance would begranted upon ROD signature. The landvault would be designed inaccordance with applicable RCRA regulations. The areas would bebackfilled following excavation activities. Following Siteremediation, the excavated areas would be vegetated. If thesubsurface excavation levels are not achieved before excavation limitsare reached, institutional controls (i.e., land and groundwater userestrictions) would be necessary to restrict exposure to thecontaminated subsurface soil and to prevent exposure to contaminatedgroundwater. The overall remedial action levels would not be achievedwithin 100 years by utilizing this alternative. Alternative 3 couldbe constructed in 12 months. The present worth cost of thisalternative is estimated at $30,359,000.6.4
Solidification/stabilization and On-SIte Diaoosal
This alternative consists oft
1. The Excavation Process
The excavation of contaminated sludge and soil within the Site untilthe established cleanup levels or excavation limits are reached.
2. Application of Innovative Technologies to Excavated Materials
Treatability studies would be conducted during the Remedial Design todetermine the effectiveness of selected technologies on soils at theSite. Three potential pre-treatment options includet(l) solventextraction, followed by liquid injection incineration; (2) lowtemperature thermal desorbtion, followed by treatment of desorbedvolatile organics/air mixture and (3) critical fluid injectionfollowed by liquid injection incineration. These options for pro-treatment would be evaluated during the design to determine if the
32
main thermal treatment process and/or cost «ffectiveness can beenhanced while still meeting levels as adjusted by the treatabilitvvariance. Tre*tability studies would be conducted to determine if thecontaminated soil* are amenable to treatment or pretreatment bydechlorination to treat the waste to LDR treatability variance levelsor to improve the performance of the Primary Treatment. These studiesmay also be used to determine if such treatment or pretreatment willimprove the performance of the solidification/stabilization of wastescontaining no gamma-BHC or organic content less than 2500 ppm.
Finally, treat-ability studies would be conducted to determine whethersolidification/stabilisation might be an effective treatmenttechnology for soils containing no gamma-BHC and containing less than2,500 ppm .total organics. This is an innovative application of thesolidification/stabilization process. If this technology is proveneffective, it will be used for these soils rather than the Primarytreatment.
3. Innovative Application of Solidification/Stabilization Technology
According to results from subsurface soil borings collected by Ciba-Geigy during RI/FS field activities, portions of Area 8 may containmanufactured pesticides that exceed the health-based cleanup levelsrequiring them to be excavated, but are not mixed with a RCRA waste.The manufactured pesticides of concern are toxicity characteristicanalytes and therefore have no toxicity characteristic regulatorylevels. Although no regulatory levels are exceeded for any toxicitycharacteristic analytes and it has been determined that the soil isnot a RCRA hazardous waste, these manufactured pesticides exceeded thehealth-based cleanup levels, requiring that they be excavated andtreated.
All soils which are mixed with a RCRA waste that exceed the cleanuplevels will undergo thermal treatment or dechlorination and be treatedto legislated (LOR) treatment standards, as adjusted by a CERCLAtreatability variance upon signing of the ROD. Additionally, it isanticipated that it will be necessary to thermally treat some of thesoil contaminated with manufactured pesticides that exceed the health-based levels which contain a total organic concentrations above 2,500ppm.Soils containing less than 2,500 ppm total organics may be amenable totreatment using a solidification/stabilization process. Thisapplication would represent an innovative application of thistechnology since BPA has minimal information on stabilization ofmanufactured pesticides. The NCP encourages the use of innovativetechnologies at Superfund sites. For this reason, and because this
33
application mayb« •ff«ctive at th« Site, solidification/stabilixationtreatment will b« evaluated during the treatability studies for thesewaste. If the stabilisation process is unsuccessful, thermaltreatment will be used to treat these waste.4. Primary Treatment r On-site Thermal Destruction
The primary treatment technology for the contaminated excavatedmaterial not amenable to final treatment by the innovativetechnologies would be on-site thermal destruction. The contaminatedsoil may require pretreatment to remove debris present before thethermal treatment process. The excavated soil would be blended in atank which meets the definition of a tank in Section 260.10 of theCode of Federal Regulations (40 CFR). The purpose of the blending isto achieve a homogeneous mixture prior to thermal treatment to ensureproper incinerator operations and to comply with operating conditionsdeterr: '.ned in the trial burn.
5. Management of Treatment Residuals and Pugmill Wastes
Ash from the thermal treatment process and any material from anytechnology selected during the Remedial Design would be disposed of ina landvault after RCRA legislated treatment standards, as adjusted bya CERCLA treatability variance, are met. Following excavation, thearea would be backfilled and revegetated.
6. In-situ Remediation ProcessesIf the excavation is terminated before cleanup levels are achieved,in-situ soil flushing would be used. In-situ soil flushing mayinvolve monitoring wells, withdrawal wells, re-injection wells andisolation walls extending from the land surface to the top of theMiocene clay, which would be used to flush contaminants from deepunsaturated sands and decrease the time required to pump and treatcontaminated groundwater.
In addition to the in-situ soil flushing, innovative technologies(in-situ vacuum extraction or in-situ bioremediation) may also be usedin addition to or instead of in-situ soil flushing, if during theremedial design either technology is found to be effective in reducingthe concentrations of the contaminants in the soil and is costeffective. This area also contains an iron slurry waste that iscompletely unsuitable for thermal treatment or pugmill stabilization.This waste would be treated by using an in-situ fixation process whichwould achieve the leachate requirements of LOR.This alternative could be implemented in 14 months. :'The present worth
34
cost of thifl fit*™tiv*' including operation and maintenance, isestimated to be $49,723,000. Thia eitiaated coat aaaumeTtnatexcavation* will continue until cleanup levels are achieved or 20 feetia reached. If excavationa 9 terminated because the groundwateriron alurry waate or large concrete boulders are encountered, the 'actual coat to implement the remedy would be reduced.
7.0 SUMMARY OP COMPARATIVE A T S Of
Thia aection of the ROD provide* the basis for determining whichalternative providea the beat balance with reapect to the statutory-balancing criteria in Section 121 of CBRCLA and in Section 300.430 ofthe NCP. The major objective of the PS waa to develop, screen, andevaluate alternatives for the remediation of the contaminated soils atthe Ciba-Geigy Site. A wide variety of technologies were identifiedas candidates for renK ' .iting the -. ntdiilnated soils at the Site.These technologies were screened baaed on their feasibility withrespect to the contaminants present and the Site characteristics. Thetechnologies that remained after the initial screening were combinedinto potential remedial alternatives and evaluated in detail. Theremedial alternatives selected from the screening process wereevaluated using the following nine evaluation criteria s
" Overall protection of human health and the environment..
" Compliance with applicable and/or relevant Federal or Statepublic health or environmental standards.
' Long-term effectiveness and permanence.
" Reduction of toxicity, mobility, or volume of hazardoussubstances or contaminants.
" Short-term effectiveness, or the impacts a remedy might haveon the community, workers, or the environment during thecourse of implementing it.
* Implementability, that is, the administrative or technicalcapacity to carry out the alternative.
* Cost-effectiveness considering coata for construction,operation, and maintenance of the alternative over the lifeof the project, including additional coats should it fail.
* Acceptance by the State.:'
35
• Acceptance by the Community.
The HCP categorites the nine criteria into three groups iC1) ThJtihoid Criteria - overall protection of human health and the
environment and compliance with ARARs (or invoking a waiver)are threshold criteria that must be satisfied in order for analternative to be eligible for selection;
(2) PftaarY Balancing Criteria - long-term effectiveness andpermanence; reduction of toxicity, mobility, or volume;short-term effectiveness; imp.lementability, and cost areprimary balancing factors used to weigh major trade-offs amongalternative hazardous waste management strategies; and
(3) Modifying Criteria - stal- and community act-.. ..c« aremodifying criteria that are formally taken into account afterpublic comment is received on the proposed plan andincorporated in the ROD.
The selected alternative must meet the threshold criteria and complywith all ARARs or be granted a waiver for compliance with ARARs. Anyalternative that does not satisfy both of these requirements is noteligible for selection. The Primary Balancing Criteria are thetechnical criteria upon which the detailed analysis is primarilybased. The final two criteria, known as Modifying Criteria, assessthe public's and the state agency's acceptance of the alternative.Based on these final two criteria, BPA may modify aspects of aspecific alternative.
The following analysis is a summary of the evaluation of alternativesfor remediating Operable Unit #4 of the Ciba-Geigy Superfund Siteunder each of the criteria. A comparison is made between each of thealternatives for achievement of a specific criterion.
Threshold Criteria7.1 QVERAIiTt PROTECTION QP HUMAN HBALTft ANTi THE ENVIRONMENT
All of the alternatives would provide protection of human health andthe environment by minimising or controlling the risk associated withthe contaminated soils through treatment or containment andinstitutional controls. In Alternative 1, the currently operatinggroundwater, pump and treat system would continue operating. However,contaminant* in the soil would continue to leach into the groundwater
36
at unacceptable levels. Cleanup levels for groundwater would not beachieved within 100 years with Alternative l! Alternative 2 wSSidisolate the contamination from the surrounding uncontaminated areaThe alternatives] involving excavation, (Alternatives 3 and 41. wouldminimize the majority of the risk by removing and treating theprincipal source of the soil and groundwater contamination and use ofinstitutional controls where necessary. However, cleanup levels forthe groundwater may not be achieved within 100 years for alternativesthat do not include deep soil treataent (Alternatives 1, 2 and 3).Alternative 4 would provide the best overall protection because itremoves and treats the principal threats between the land surface andthe excavation limits and it provides deep in-situ soil treatment forcontaminated soils below the excavation limit*-.7.2 COMPLIANCE WITH ARARq
All c ' "he alternatives would comply with all Federal or State ARAB.Sor justify a waiver. Chemical specific ARARs would be met throughcompliance with the groundwater protection standards (ie., MCLs) atthe Point of Compliance as defined in Ciba-Geigy's RCRA permit andthrough compliance with the MPDBS permit conditions for water removedand treated in the waste management areas. The landvault utilized inAlternatives 3 and 4 would be designed in accordance with RCRAregulations. Soils excavated in Alternatives 3 and 4 would beanalyzed to determine if they are RCRA hazardous waste. If required,RCRA hazardous waste would be treated to legislated treatmentstandards pursuant to a treatability variance prior to land disposal.Highly concentrated soils would be treated by a thermal treatmentprocess designed to comply with RCRA regulations for hazardous wastethermal treatment. It is not anticipated Alternative 3 would achievethese standards for many of the contaminants of concern due to theelevated levels present in the contaminated soil. Alternative 4would be designed to attain these standards as adjusted by thetreatability variance .Air emissions from the Site would be monitored to ensure compliancewith the Clean Air Act. Fence line air monitoring will be conducted toensure that contaminant concentrations do not exceed levels consideredto be safe for human health. If levels are exceeded, mitlgativeprocedures such as dust suppression or vapor capture will be employedto prevent harmful levels of air emissions from leaving the Site.RCRA design standards will be incorporated into the remedial design ofall remedial activities. Of the four alternatives, alternativesalternative t4 provides the best compliance with ARARs.
Primary Balancing Criteria
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7.3 T/>BG-TH« grTKTIVKNgfiff AMD
Altjrnativ* 1 would not provide long-term •ffectlveness and permanencewith respect to the contaminated soils at the Site. Bach of theremaining alternatives would provide long-term effectiveness throughlimiting th«) migration of contamination or treatment of thecontaminated soils at the Site. Over time the effectiveness ofAlternative 2 may decrease as a result of cap/. lurry wall failurecaused by improper construction (i.e., keying of t£ wall into wunfractured impermeable clay layer) or Inadequate operation andmaintenance procedures. However, as long as the cap and sTurrv wallare properly maintained, the alternative would be effective. InAlternative 3, the contaminants are bound to the soil by the treatnentprocess and the solidified material is contained on- site in a RCRAlandfill. The long-term effectiveness of Alternative 3 is uncertainsince solidifying high level organic contamination has not beendemonstrated to be effective in preventing leaching of the waste int-the ^roundwater. Alternatives 4 provides a greater level of long-termeffectiveness than Alternatives 2 and 3 because thermal treatment hasbeen demonstrated to effectively destroy contaminants to the levelsallowed by the treatability variance. Alternative 4 provides thegreatest long-term effectiveness and permanence by the additionaltreatment of contaminated soils-- below the excavation limits.
7 . 4 REDUCTION OF TQXICITY. MOBILITY OR VOLUME THROUGH TREATMENT -
Alternative 1 would not reduce mobility, toxlcity or volume at thesource of the contamination. Alternative 2 would isolate thecontamination from the environment, thus minimizing the forces whichdrive contaminant mobility. However, toxicity and volume would not beaffected by Alternative 2. Each of the remaining alternatives wouldreduce the mobility of the contaminants through treatment.Treatability Studies would be conducted to demonstrate the level ofmobility reduction resulting in the solidification/stabilizationprocess proposed in Alternative 3. However, the volume ofcontaminated material in Alternative 3 would increase due to thestabilization process. Alternative 3 would provide minimal reductionin toxicity. The toxicity of chemical contaminants at the Site wouldbe reduced by the thermal destruction process in Alternative 4.Thermal treatment and destruction of the organic chemical contaminantsat the Site through Alternative 4 would virtually eliminate all toxiceffects of the excavated soils along with a substantial reduction involume. Alternative 4 provides the best reduction of toxicity andmobility through treatment by utilising innovative in-situ treatmentsfor contaminated soils currently below the excavation limits.
38
Alternative 1 would not require construction or excavation that wouldcause • 5«*lt* *i«k to worker.. However, Alternative 1 would be theleast •"•C51T? " achieving the overall groundwater cleanup levels inthe shortest time period. All of the regaining alternative, willrequire varying amount, of time to implement. Hone will beimmediately effective. No threshold toxic ity criteria would beexceeded by implementing Alternative. 2, 3, and 4 and the health risksto remedial worker, i. unlikely, particularly when appropriatemonitoring and engineering control, are applied. Of the alternativesevaluated, Alternative. 3 and 4 are more effective than Alternative 2because contaminated .oil would be removed and treated. AlthoughAlternative 3 require, removal of contaminated .oil. down to theexcavation limit.. Alternative 4 would be meet effective in theshort-term by isolating and treating the contaminated soils below theexcavatic;. limits. These soil, are causing the most immediate threatbecause of their proximity to the groundwater.
7.6 IFP KBNT ABILITYAlternative 1 is currently operating. Technological expertise,service., equipment and material, are adequately available for theimplementation of Alternative 2. Due to the uncertainty regarding theeffectiveness of solidification/stabilisation of material contaminatedwith elevated concentrations of organic contaminant, a treatabilitystudy would be conducted. A determination would be made at thecompletion of the treatability studies, to be conducted during theremedial design, regarding the effectiveness ofsolidification/stabilization of material contaminated with elevatedconcentrations of organic contaminants.Thermal treatment capacity may be limited at the time ofimplementation of Alternative 4. New equipment may have to bedesigned and constructed as a part of the overall schedule. However,the technology base does exist for the completion of this requirement.Ash from the thermal treatment process, any solidified/stabilizedmaterial or any material from the dechlorination process would bedisposed of in a landvault after RCRA legislated treatment standards,a* adjusted by a treatability variance granted upon ROD signature, aremet. In accordance with Super fund LDR Guidance #6A, for herbicides,which are similar and applicable to Sit* contaminants, the selectedtechnology must demonstrate a 90-99.9 percent reduction for thecontaminants of concern to be granted the variance. All of thealternatives are technically and administratively feasible. However,the results of the treatability studies would determine theeffectiveness of Alternative 3 on elevated levels of organics.
39
7.7
Alternative 1 would not require any additional co.t gince no treatmentof the .ourc« 1. provided. The present worth co.t of inltalliJS alurry "fll •**«•? (Alternative 2) 1. e.timated to be $10?909?000.Alternative. 3 and 4 are .ub.tantially higher in co.t due 4o iAcreasedeffort, to permanently treat the contaminated soil. The present "co.t associated with solidification/stabilisation of the S"Ja£I
K, 530,359,000. Thermal treatment and/orBolidification/.tabili.ation of the contaminant, in the soil(Alternative 4) would co.t approximately $49,723,000. This cost couldvary depending on the result, of a treatability .tudy to verify thelevel, of contamination which could be .olidified and still achieveRCRA land disposal standard, a. adjusted by a treatability varianceand by the volume of soils which ~*n be excavated b-'-re excavaflimits are reached. The treatabi.xty study would bt conducted dun:.the remedial design to verify the level of contamination which could'be solidified/stabilized and still achieve RCRA land disposalstandard, pursuant to a treatability variance. The.e cost, includeoperation and maintenance during the implementation of the alternativea. well a. post remediation monitoring.
Modifying Criteria
7.8 STATS ACCEPTANCE
The State of Alabama has concurred with the selection of Alternative 4to remediate the contaminated soil at the Ciba-Geigy Site.
7.9 COMMUNITY ACCEPTANCE
Based on the favorable comments expressed at the May 19, 1992 publicmeeting and the lack of negative written comments received during thecomment periods, it appears that the Mclntosh community generallyagrees with the selected remedy.
8.0 SUMMARY OF SBLBCTBP REMEDYIn summary, Alternative 4 will achieve substantial ri.k reductionthrough treatment of a principal threat at the Ciba-Geigy SuperfundSite. LOR treatment .tandards will be achieved, a. adjusted pursuantto a treatability variance, granted upon ROD signature, prior to
40
placing the treated •«:avat«d material in the on-site landvauitshown in Figur* 4, the treatment technology which has bieTd 0 r a * d l M "••"d!T0S?Jra?*«.£™lM "••" «**«*Md« for the RCRA was. present atthe Sit* is thftr»al treatment. Thermal treatment in this^lternativemay al.o include a pre-treatment phase prior to the «ain therllltreatment process. Three potential pre-treatment options include,iii Jem uS'Sii™? £? ? bLllqUi<1 i«l~t^ in ne aSon (2)low temperature thermal, followed by treatment of the desorbedT°}?Jii! f?10? *1* "! and (3) <=^tical fluid injection,followed by liquid injection incineration. These option* forpre- treatment will be evaluated during treatability studies to beconducted during the remedial design to determine if the main thermaltreatment process and/or cost effectiveness can be enhanced whilestill meeting levels as adjusted by the treatability variance, if anyof the technologies are proven to enhance cost effectiveness or themain thermal process, it will be used.
Under certain circumstances, the pre-treatment option could totallyreplace the main thermal treatment process. If any of thepro-treatment technologies are proven to be more effective in reducingthe contaminant concentrations in the soil and more cost effective, itwill be used instead of the main thermal treatment process.Pre- treatment technologies that are not found to be effective inreducing contaminated soil concentrations to levels required pursuantto the treatability variance or that do not enhance cost effectivenesswill not be utilized.
Treatability studies will be conducted to determine the effectivenessof solidification/stabilization of soils with low levels ofcontamination.
According to results from subsurface soil borings collected by Ciba-Geigy during RI/FS field activities, portions of Area 8 may containmanufactured pesticides that exceed the health-based cleanup levelsrequiring them to be excavated, but are not mixed with a RCRA waste.The manufactured pesticides of concern are toxicity characteristicanalytes and therefore have no toxicity characteristic regulatorylevels. Although no regulatory levels are exceeded for any toxicitycharacteristic analytes and it has been determined that the soil isnot a RCRA hazardous waste, these manufactured pesticides exceeded thehealth-based cleanup levels, requiring that they be excavated andtreated .All soils which are mixed with a RCRA waste that exceed the cleanuplevels will undergo thermal treatment or dechlorination and be treatedto legislated (LDR) treatment standards, as adjusted by a CBRCLAtreatability variance upon signing of the ROD. Additionally, it is
41
anticipated that it will be necessary to thermally tr«at S•oil contaminated with manufactured pesticide! that exceed .-based level, which contain a total organic concentrationTabo. 2 sooppm. '
Soil* containing less than 2,500 ppm total organics may be amenable totreatment uaing a solidification/stabilization process! Thisapplication would represent an innovative application of thistechnology since EPA has minimal information on stabilisation ofmanufactured pesticides. The MCP encourages the use of innovativetechnologies at Superfund sites. Por this reason, and because thisapplication may be effective at the Site, solidification/stabilizationtreatment will be evaluated during the treatability studies for thesewaste. If the stabilixation process is unsuccessful, thermaltreatment will be used to treat these waste.
In o-der to conduct the solidification/stabilization treatabilitystudies, it will be necessary to identify treatment standards withwhich to evaluate the effectiveness of the technology.Solidification/stabilization may involve physical/chemical processesthat do more than simply entrap the contaminants. Solidificationperformed in conjunction with stabilization would satisfy thepreference for treatment under Superfund and falls within theprogram's definition of immobilization.Concerns have been raised regarding the types of iomobilization thatprovide for adequate protection. The principal reason for theseconcerns rests on the fact that immobilization is not generallyconsidered a destructive technique but rather prohibits or impedes themobility of contaminants.
Although experts are in general agreement regarding the effectivenessof Immobilization for most inorganics and metals, the effectiveness ofimmobilization for organics cannot be predicted without testing.Furthermore, the testing methods available (i.e. leachability tests)provide different types of information on the mobility of contaminantsdepending on the test. For these reasons, Superfund has developedgeneral guidelines for evaluation and selecting immobilization takinginto consideration the testing methods currently available, scientificunderstanding to date, and the NCP expectations regarding treatment.The preamble to the NCP (SSFR page 8701, 03/08/90) provides thefollowing guidance regarding treatment effectiveness!
"... The Superfund program also uses as a guideline foreffective treatment the range 90 to 99 percent reduction in theconcentration or nobility of contaminants of concern....BPAbelieves that, in general, treatment technologies or treatment
42
train* that cannot achieve this level of performancess'srs.'.""1*1""' '"~"~ —n««d.pollcy "d curr*nt
SDPBRFUND POLICY OM USB OF IKMOBILISATION
Agency policy on the use of immobilization for treatment in view ofconcerns that have been railed regarding technology performanceprimarily for organic • is as follows i
Immobilization is generally appropriate as a treatmentalternative only for material containing inorganics, semi-volatile and/or non-volatile o-cyanics. Based on presentinformation, the Agency does not believe that immobilization isan appropriate treatment alternative for volatile organic s.Selection of immobilization of semi-volatile and non-volatileorganics generally requires the performance of a site specifictreat ability study data generated on waste which is verysimilar (in terms of type of contaminant/ concentration andwaste matrix) to that to be treated and that demonstratedthrough Total Waste Analysis (TWA), a significant reduction(i.e., a 90 - 99 percent reduction) in the concentration ofchemical constituents of concern.
The need for treatability study data and the importance of conductingappropriate leachability tests as part of the study are importantparts of this policy statement. Treatability studies to demonstratethe effectiveness of treatment of organics is needed since we do notbelieve that we can predict the degree of performance which may beprovided without such testing.
EPA believes that given the uncertainty associated with immobilizationof organics, the most stringent leachability test available (i.e.Total Waste Analysis (TWA)) should be used to demonstrate theeffectiveness of the technology. A successful demonstration using TWAprovides a measure of assurance regarding the leachability of theorganics. TWA does not mirror environmental conditions, however/ anddoes not provide) information on the protectiveness under specificmanagement scenarios for the immobilized product. One or moreleachability tests will be used to evaluate thesolidification/stabilisation technology.
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R1ASOBS Solidification/stabilization TWtAIMKHT STANDARDS MOST BBESTABLISHED FOR 00*4 A3 TES CIBA-G8IGY Sitet
1. A volume of the waste to be excavated may contain waste(manufactured pesticides) that exceed health-based levels. Holegislated treatment standards exist for these manufacturedpesticides.
2. The proposed treatment must meet Superfund'* effectivetreatment requirements of 90 - 99 percent reduction in concentrationor mobility.
3. The Dilution Attenuation Factor (OAF) of 45 is the moreconservative of the dilution factors used in generating the health-based cleanup levels at the Site. The OAF of 45 x the groundwaterpr-- tectirn standa I is tha concentratl .1 of leachate EPA hasdetermined to be safe for the groundwater using the Pestan Model. ThePestan Model assumes that an uncontaminated zone a minimum of four (4)feet exist between the contaminated waste and the groundwater surface.
This decision is more conservative than the 1986 TCLP Rule of RCRA,which added 25 new organic constituents to the list of toxicconstituents of concern. The 1986 TCLP rule establishes regulatorylevels for the organic constituents based on health-basedconcentrations and a OAF developed using the subsurface fate andtransport model. In the 1986 TCLP Rule EPA determined, based on theresults of its subsurface fate and transport model, that use of a DAFof 100 is appropriate for setting regulatory levels. (This DAF issufficient to capture on those waste that are clearly hazardous).
4. In addition, the dilution factor of 45 is more conservativethan the DAF of 100 used in the 1986 TCLP Rule.
5. After the material is stabilized/solidified, it will be placedin a RCRA class C landvault which will have a leachate collectionsystem and liner. The landvault will prevent water or any otherliquids from contacting the treated material and the treated materialsor any potential leachate will not contact the underlying clean soil.
45
Figure 5
TREATMENT OF EXCAVATED CONTAMINATED SOILSPROCESS FLOW CHART
-^• •OIVIWT IITNACTION
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Solidlfication/ttabilitation will b, utili«ed for soils mixed with »RCKA wa«t« where it is proven effective by these treatability studiesin reducing the contaminated soil concentration, to LDR treatabnltvvariance l«v«l« or for toil, containing manufactured pesticides thatexceed the health-based levels where the performance standard! foreffective •olidification/stabilization are net. «o«ra« tor
A new innovative chemical treatment technology, dechlorination, may betested during design and, if found effective, may be used instead ofsolidification/stabilisation for some low level soils. Dechlorinationuses a base (i.e., sodium hydroxide) and an organic source of hydrogenand a catalyst to accomplish reductive dehalogenation of halogenatedmaterials. If dechlorination is proven to be more effective inreducing the contaminant concentrations in the soil and is sore costeffective, it will be used instead of the solidification/stabilizationprocess. If dechlorination is proven ineffective in reducingcontaminated soil concentrations to levels pursuant to thetreatability variance and/or does not enhance cost effectiveness itwill not be utilized.
The contaminated soil may require pre-treatment to remove debris(i.e., drums, scrap metal, construction rubble etc.) present beforethe thermal treatment process. At the time of excavation during theremedial activities, the debris may be removed from material that isrequired to be treated. If drums are encountered, the contents willbe removed from the drums and it will be tested to determine if it ishazardous waste. A determination will be made based on a method to bedetailed in the remedial design phase of the project as to thehazardous or non-hazardous nature of the debris. If the debris isdetermined to be of a non-hazardous nature, it may be decontaminatedand separated into a category of materials that can be disposed ofoff-site and/or recycled. Debris that is determined to be of ahazardous nature will be treated in an appropriate manner to bedetermined at the time of excavation.
The soils to be thermally treated would be blended in a tank whichmeets the definition of a tank in Section 260.10 of the Code ofFederal Regulations (40 CFR). The purpose of the blending is toachieve a homogeneous mixture prior to thermal treatment to ensureproper thermal treatment operations and to comply with operatingconditions determined in the trial burn. Ash from the thermaltreatment process, any solidified/stabilized material or any materialfrom the dechlorination process will be disposed of in a landvaultafter RCRA LDR treatment standards, pursuant to a treatabilityvariance granted upon ROD signature, are met. In accordance withSuperfund LDR Guidance #6A, for herbicides, which are similar andapplicable to Site contaminants, a treatability variance requires that
47
th« j«l«ctjd tjjchnolojy «ust demonstrate a 90-99.9 percentin the contaminants of concern.
£!L?5?*f,t0 SfSJid* * conatant treatment criterion throughout the£I???iJi JhS S!!" !**f? Wili ensur» <=°»Pliance with the treatabilityI5fi !:-J2!«? Sf*ntS!tiOIX °f **ch contaminant of concern in the .oilafter treatment suet be no greater than 10% of the correspondingcleanup level. Adherence to thi. criterion will ensure aVLni.ii Of90% reduction as required by tiie treatability variance. Therequirement that treated soils contain a concentration less than orequal to a 90% reduction of the cleanup levels is based on theassumption that the cleanup levels are the lowest concentrations ofsoils that will be excavated. Ensuring that the cleanup levels arereduced by 90% (leaving a maximum of 10%) complies with the lowerlimit of the percentage reduction allowed by Superfund LOR Guidance6A. In addition to providing a constant treatment level, the soilbefore treatment will not hf to be analyzed other than for processcontrol.
In some cases treatability variance standards may be more stringentthan the upper limit of 99.9% in Superfund LDR Guide #6A. Forexample, if Gamma-BBC were found at 1000 mg/kg in a Summer's Modelarea before treatment, requiring that it be reduced to 0.1 mg/kg, aain Table 8-1, would amount to a 99.99% reduction. This percentreduction would still be less stringent than the LOR treatmentstandards of 0.066 mg/kg and 0.087 mg/kg for BHCs and DDTsrespectively. Therefore, the treatability variance will still beapplicable.
Table 8-1 provides the treatability variance treatment levels for thecontaminants of concern for this operable unit and some additionalRCRA waste which are present in other areas at the Site and may befound in low concentrations in this area (no confirmatory data at thistime). These treatment levels must be achieved prior to placement oftreated soils into the RCRA landvault.
Confirmatory samples will be conducted during the remedial design toensure that contamination is not present above cleanup levelsestablished in the ROD for surface and subsurface soils.
If confirmatory samples indicate that concentrations of subsurfacesoils are above cleanup levels, institutional controls, including deedrestrictions sad/or other measures necessary will be utilised toensure that any future excavations of the contaminated soil willinclude the same handling and treatment as set out in the selectedremedy. .. :
48
Following excavation activities, the area will be backfilled andrevegetated. As presented in Figure 5 (flow chart), if cleanup levelsare not achieved before excavation levels are reached, extractionwells combined with isolation walls extending frosi the land surface tothe top of ths) Miocene clay and in-situ soil flushing will be utilizedto flush contaminants frosi deep unsaturated soils, thus decreasing thetime required to operate the pump and treat system implemented inoperable unit one. The contaminated groundwater extracted by thesewells will be treated by the currently operating waste water treatmentsystem. Innovative technologies (in-sltu vacuum extraction or in-aitubioremedlatlon) may also be used in concert with the soil flushingapproach, if during design they are found to be effective in reducingsoil concentrations to cleanup levels. Institutional controls, suchas deed restrictions, will be established to preclude usage ofgroundwater and minimize land use until cleanup levels are achieved.
The results of the treatability B' JL»a for all tech-.-logiea testedduring the remedial design will be evaluated and the technologies tobe used for remediation of the contaminated soils would be determinedand noted in the 30% Remedial Design Report. EPA will then issue apublic notice in a local newspaper and send a fact sheet to persons onthe mailing list to inform the public of the technologies proveneffective and which are to be implemented.
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IABLB 8-1STANDARD FOR SOILS AT THI CZBA-GBZOT Sit*
The following table provide* the maximum concentrationallowed in the residuals after treatment for the contaminants ofconcern.
A N O U M O T N I C O N T A M I N 4 T I DAHIA «MO T N I A T M I N TTHIS MAT II • U P ' L C M t N T I OTHIS MAY II•UPPIIMINTIO (V OKI OHMOM TICNMOLOai l l » M O V I N
t»»ICT(V| IM
•TUOIIt
eONTINUI Oil* (OILMMCDIATION UNTIL •!•«. ;• ACID • •OUNOMhTlft C L I A M U * !LIVIL* A»« A«M|IVIO AT T M I JVITNOKMkL
O O M T I N U I ••OUMOWTI*M O H I T O M I M * W M T I LOVIRAkk •MOUHDWriNO b l A M U r l lVIk* A M IM N I I V I O .
Air emission* from the Site will be monitored to ensure compiianc-with the Clean Air Act. Fenceline air monitoring will be wndScled toensure that contaminant concentrations do not exceed levels consideredto be safe for human health. If levels are exceeded, mitigativeprocedures such a« dust suppression or vapor capture will be employedto prevent harmful levels of air emissions from leaving the Site.
All treated wastes will be land disposed in accordance with thesubstantive requirements of the Land Ban Regulations, pursuant toSection 3004 of the Resource Conservation and Recovery Act of 1976(RCRA), as amended by the Hazardous and Solid Waste Amendments of 1984(HSWA).
After excavation and treatment, treated wastes will be land disposedwhen L?R treat-ant sto^Jards for any char<^_ceil_ cic waste, listedwaste, or regulated hazardous constituent as adjusted by thetreatability variance granted upon ROD signature are met. Thetreatment standards are based on the performance of treatmenttechnologies determined by the Agency to represent Best DemonstratedAvailable Technology (BOAT) as .promulgated on June 1, 1990. Wastesthat, as treated, contain RCRA hazardous wastes or hazardous wasteconstituents, at concentrations which do not exceed the treatmentstandards, are not restricted from land disposal units.
The selected alternative for the Ciba-Geigy Site is consistent withthe requirements of Section 121 of CBRCLA and the National ContingencyPlan. The selected alternative will reduce the mobility, toxicity,and volume of contaminated soil at the Site. In addition, theselected alternative is protective of human health and theenvironment, will attain all Federal and State applicable or relevantand appropriate public health and environmental requirements through aLDR treatability variance, is cost-effective and utilizes permanentsolutions to the maximum extent practicable. The selected alternativefor Operable Unit No. 4 is consistent with previous remedial actionsconducted at the Site.
Based on the information available at this time, the selectedalternative represents the best balance among the criteria used toevaluate remedies. Alternative 4 is believed to be protective ofhuman health And the environment, will attain ARARs (throughapplication of the- treatability variance), would be cost effective,and would utilize permanent solutions and alternative treatmenttechnologies or resource recovery technologies to the maximum extentpracticable.
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9.0
Under its legal authorities, EPA's primary responsibility at Suoerfund.it., is to undertake radial actions that achieve adeqJaJe 5Uperfundprotection of human health and the environment. ^^
In addition, Section 121 of CBRCLA establishes several other statutoryreqtiirementsand preferences. Theee specify that, whencomplete th?selected remedial action for this Site'mu.t compl^ h SfiSable o?relevant and appropriate environmental standard!, established undejFederal and State environmental laws unless a statutory waiver isjustified•
The selected remedy also must be cost-effective and utiliie permanentsolutions and alternative treatment technologies or resource recoverytechnologies to the maximum extent practicable. Finally, the statuteincludes a preference for remedies that employ treatment thatpermanently and significantly reduce the volume, toxicity, or mobilityof hazardous wastes as their principal element. The followingsections discuss how the selected remedy meets these statutoryrequirements.
The selected remedy protects human health and the environment throughtreating a principal threat remaining at the Site, the contaminatedsoils at former waste management area 8 addressed in this ROD. Theselected remedy provides protection of human health and theenvironment by eliminating, reducing, or controlling risk throughtreatment, engineering controls and/or institutional controls.
9.2 ATTAINMENT OF THE APPLICABLE OR RELEVANT AND APPROPRIATEREQUIREMENTS (ARARsl
Remedial actions performed under CERCLA must comply with allapplicable or relevant and appropriate requirements (ARARs). Allalternatives considered for the Ciba-Geigy Site were evaluated on thebasis of the degree to which they complied with these requirements.The selected remedy was found to meet or exceed the following ARARs,as discussed below.Clean Water Act
Perched water at certain areas and stomwater which contacts Sitematerials during remediation activities will be routed through theexisting on-site wastewater treatment plant. In addition,contaminated groundwater extracted by the deep soil treatment
53
vapor capture will be employed to prevent harmful levels of air••islions fro» leaving the Site.
Kaxlmum Contaminant Levels (MCL«) and non-iero MCLGs are theGroundvater Protection Standard* set out in the Corrective ActionProgram required by the 1985 RCRA Part B Permit. Those Standards havebeen incorporated into the CBRCLA ROD (September, 1989) for the FirstOperable Unit, addressing the alluvial aquifer, and are indicated inTable 5-6.
Waivers
No ARAR waivers are h^ing granted howevsr, the selected alternativewill comply with the LDRs through a treatability variance for thecontaminated soil and debris.
9.3 COST EFFECTIVENESS
The estimated cost of EPA's selected remedy is approximately$49,723/000. This cost would be reduced if excavation limits arereached before cleanup levels are achieved. Cost effectiveness isdetermined by comparing the cost of all alternatives being consideredwith their overall effectiveness to determine whether the costs areproportional to the effectiveness achieved. EPA evaluates theincremental cost of each alternative as compared to the increaeeffectiveness of the remedy. The selected remedy, Alternative^,although most costly, was chosen for its high degree of effectivenessat reducing the mobility, toxicity, and volume of the contaminants andits long-term protectiveness. BPA has determined that the cost of theselected remedy is proportional to the overall effectiveness;therefore, the remedy is considered cost effective.
9.4 UTILIZATION OF PERMANENT SOLUTIONS TO THE MAXIMUMEXTENT PRACTICABLE
EPA believes the selected remedy is the most appropriate cleanupsolution for Operable Unit 4 of the Ciba-Geigy Site and provides thebest balance among the evaluation criteria for the remedialalternative* evaluated. This remedy provides effective protection inboth the short-term and long-term to potential human and environmentalreceptors, is implementable, and is cost-effective. ::
55
Thermal treatment of the highly contaminated toils, with pre-treatmentoptions proven effective during the design, and•olidificatioa/etabilitation or dechlorination of low levelcontaminated aoil, if proven effective during the design, withlandvault diepoeal of the residuals, will effectively reduce and/oreliminate the Mobility of hazardous waste and hazardous substances tothe environment. Isolation from the groundwater combined vith in-situtreatment of any contaminated soils below the depth where excavationsare terminated will effectively reduce and/or eliminate the mobilityof hazardous waste and hazardous substances to the environment.
The statutory preference for treatment will be met because theselected remedy treats the highly contaminated and most mobilecontaminated soils, a principal thxeat */osed by the Site/ and isolatesand treats the lower contaminated soils.
10.0 DOCUMENTATION OP SIGNIFICANT CHANGES
A change has been made to the Selected Remedy since the Proposed Planwas issued. This change was prompted by comments received during thecomment period. Solidification/stabilization was considered in thealternatives for some wastes and will be tested for application toanother waste type aside from those discussed previously.
According to results from subsurface soil borings collected by Ciba-Geigy during RI/PS field activities, portions of Area 8 may containmanufactured pesticides that exceed the health-based cleanup levelsrequiring them to be excavated, but are not mixed with a RCRA waste.The manufactured pesticides of concern are toxicity characteristicanalytes and therefore have no toxicity characteristic regulatorylevels. Although no regulatory levels are exceeded for any toxicitycharacteristic analytes and it has been determined that the soil isnot a RCRA hazardous waste, these manufactured pesticides exceeded thehealth-based cleanup levels, requiring that they be excavated andtreated.All soils which are mixed with a RCRA waste that exceed the cleanuplevels will undergo thermal treatment or dechlorination and be treatedto legislated (LDR) treatment standard*, as adjusted by a CBRCLAtreatability variance upon signing of the ROD. Additionally, it isanticipated that it will be necessary to thermally treat some of thesoil contaminated with manufactured pesticides that exceed the health-based level* which contain a total organic concentrations above 2,500ppm. -
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amenable to^
Soils containing lets than 2,500 pp. total organics may betreatment uaing a •oUdification/ltabilitatioii process: Thiapplication mid represent an innovative application o£ thistechnologyiiince m ha. minimal information on .tabilisatioJ ofmanufactured pe.ticides. The HCP encourages the use of innovativetechnologies at Superfund Sit... For thii reason, and bicauIJ thi
0 7 * * * * * Sit«' •olidification/.tSblllza. ' c a o n . t z a otreatment will be evaluated during the treatability studies for thesewaste, if the stabilization process is unsuccessful, thermaltreatment will be used to treat these waste.
In order to conduct the solidification/stabilisation treatabilitystudies, it will be necessary to identify treatment standards withwhich to evaluate the effectiveness of the technology.Solidification/stabilization may involve physical/chesLtcal processesthat do more than simply entrap the contaminants. Solidificationperformed in conjunction with stabilization would satisfy thepreference for treatment under Superfund and falls within theprogram's definition of immobilization.
Concerns have been raised regarding the types of immobilization thatprovide for adequate protection-. The principal reason for theseconcerns rests on the fact that immobilization is not generallyconsidered a destructive technique but rather prohibits or impedes themobility of contaminants.Although experts are in general agreement regarding the effectivenessof immobilization for most inorganics and metals, the effectiveness ofimmobilization for organics cannot be predicted without testing.Furthermore, the testing methods available (i.e. leachability tests)provide different types of information on the mobility of contaminantsdepending on the test. For these reasons, Superfund has developedgeneral guidelines for evaluation and selecting immobilization takinginto consideration the testing methods currently available, scientificunderstanding to date, and the MCP expectations regarding treatment.The preamble to the NCP (SSPR page 8701, 03/08/90) provides thefollowing guidance regarding treatment effectiveness!
"... The Superfund program also uses as a guideline for effectivetreatment the range 90 to 99 percent xeduction in theconcentration or mobility of contaminants of concern. .. .EPAbelieves that, in general, treatment technologies or treatmenttrains that cannot achieve this level of performance on aconsistent basis are not sufficiently effective and generally willnot be appropriate."
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Tta tu* o* any trMtMnt technology, including taobiliiaUon,11*' °UC "* CU"'nt d
SDPBRFUHD POLICT OH US* OP IMMDBILISATIOM
Agency policy on «*•«• of immobilization for treatment in view ofconcerns that have been raised regarding technology performanceprimarily for organic* is as follow* t t~**w«»*nc.
Immobilization is generally appropriate as a treatment alternativeonly for material containing inorganics, semi-volatile and/or non-volatile organic*. Based on present information, the Agency doesnot believe that immobilization is an appropriate treatmentalternative for volatile organics. Selection of immobilization ofsemi-volatile and non-volatile organics generally requires theperformance of a site specific treatalllity study data generatedon waste which is very similar (in terms of type of contaminant,concentration and waste matrix) to that to be treated and thatdemonstrated through Total Waste Analysis (THA), a significantreduction (i.e., a 90 - 99 percent reduction) in the concentrationof chemical constituents of/concern.
The need for treatability study data and the importance of conductingappropriate leachability tests as part of the study are important.parts of this policy statement. Treatability studies to demonstratethe effectiveness of treatment of organics is needed since we do notbelieve that we can predict the degree of performance which may beprovided without such testing.EPA believes that given the uncertainty associated with immobilizationof organics, the most stringent leachability test available (i.e.Total Waste Analysis (TWA)) should be used to demonstrate theeffectiveness of the technology. A successful demonstration using TWAprovides a measure of assurance regarding the leachability of theorganics. TWA does not mirror environmental conditions, however, anddoes not provide information on the protectiveness under specificmanagement scenarios for the immobilized product. One or moreleachability tests will be used to evaluate thesolidification/stabilisation technology.
The 90 - 99 percent reduction in contaminant concentration is ageneral guidance and may be varied within a reasonable rangeconsidering the effectiveness of the technology and the clean-up goalsfor the Site. Although this policy represents BPA's strong beliefthat TWA should be used to demonstrate effectiveness ofimmobilization, other leachability tests may also be 'appropriate in
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addition to THA to evaluate the protectivenesi for a soecificmanagement scenario. *
Sine* the Solidification/stabilization technology la not a proventreatment technology for organic*, treatment effectiveness will beassessed u.ing the TCLP, Hultiple Extraction Procedure and Total Waste?ai?7faJF f! 5°r **?,«*nufactured pesticides at the Site. Thestabilized soils from this Site oust achieve the followingrequirements for the technology to be considered effective.
1. The boiling point of the contaminants to be stabilized must behigher than the boiling point of water. During the stabilizationprocess provisions must be made to ensure that none of thecontaminants volatilize. The temperature of the process should notexceed 130 degrees P.
2. The TCLP leachate from stabilized/soliU.fled Bella would berequired to at a minimum yield a leachate that would not exceedgroundwater protection standard multiplied by the mostconservative of the dilution factors used (45) to generate cleanuplevels for the contaminants of concern at the Site.
3. TKA will be run and compared to the original analysis of wasteusing the same extraction procedures. A 90% reduction inconcentration or mobility of the contaminated soil after treatmentis the treatment goal.
4. In addition, the solidification/stabilization mixture would berequired to achieve a minimum of 250 psi compressive strength andmust demonstrate a permeability of IxlO*4 or less.
Excavated soil requiring treatment which could not comply with thesestandards would be thermally treated or treated by dechlorination.During the Remedial Design, the treatment standards would be used todetermine the efficiency of the solidification/stabilizationtechnology.This decision is consistent with Superfund's guidelines for effectivetreatment which recommends a treatment range of 90 to 99 percentreduction in the concentration or mobility of the contaminants ofconcern.
REASONS Solidification/stabilization TREATMENT STANDARDS MOST BEESTABLISHED FOR OU»4 AT THE CXBA-GEIGT Sites
1. A volume of the vast* to be excavated may contain waste
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(manufactured pesticides) that exceed health-based levels. NOlegislated treatment standards exist for these Manufacturedpesticides.
2. The proposed treatment must meet Superfund's effective treatmentrequirements of 90 - 99 percent reduction in concentration ormobility.
3. The dilution factor of 45 is the more conservative of the dilutionfactors used in generating the health-based cleanup levels at theSite. The DAP of 45 x the groundvater protection standard !• theconcentration of leachate BPA has determined to be safe for thegroundvater using the Pestan Model. The Pestan Model assumes that anuncontaminated zone a minimum of four (4) feet exist between thecontaminated waste and the groundvater surface.
This decision is ffl<r-9 conservative than the 199S TCLP Rule cf RC?_\,which added 25 new organic constituents to the list of toxicconstituents of concern. The 1986 TCLP rule establishes regulatorylevels for the organic constituents based on health-basedconcentrations and a Dilution Attenuation Factor (OAF) developed usingthe subsurface fate and transport model. In the 1986 TCLP Rule BFAdetermined, based on the results of its subsurface fate and transportmodel, that use of a DAF of 100 is appropriate for setting regulatorylevels. (This DAF is sufficient to capture on those waste that areclearly hazardous).
4. In addition, the dilution factor of 45 is more conservative thanthe DAF of 100 used in the 1986 TCLP Rule.
5. After the material is stabilized/solidified, it will be placed ina RCRA class C landvault which will have a leachate collection systemand liner. The landvault will prevent water or any other liquids fromcontacting the treated material and the treated materials or anypotential leachate will not contact the underlying clean soil.
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APPENDIX A
Responsiveneae Summary
Ciba-Geigy Site
Mclntosh, Washington County/ Alabama
nSFQBSIVKHKSS SUMMARY
The U.S. Kavironmental Protection Agency (BPA) established apublic comment period from April 30, 1992 through May 29, 1992for interested parties to comment on EPA's Proposed Plan (PP) forOperable Unit 14 at the Ciba-Geigy Site. The comment periodincluded a public meeting on May 19, 1992, conducted by EPA andAlabama Department of Environmental Management (ADBM) , held atthe Mclntosh Town Hall in Mclntosh, Alabama. The meetingpresented the result* of the studies undertaken and the preferredremedial alternative for 00 #4.
A responsiveness summary is required by CERCLA (Superfund)Section 117 and it is policy to provide a summary of significantpublic comments and concerns about the Sit^, as rai^^d during thepublic comment period and the public meeting, and the Agency'sresponses to those concerns. All comments summarized in thisdocument have been factored into the remedy selection process foecleanup of the Ciba-Geigy Site, Operable Unit #4.
This responsiveness summary for the Ciba-Geigy Site is dividedinto the following sections!
I. Overview i This section discusses the recommendedalternative for remedial action and the public'sreaction to this alternative.
section provides a brief history of community interestand concerns regarding the Ciba-Geigy Site.
Ill • Sjinmjftrv of Ma^or Questions and Consents Received Duringthe Public Comment Period and EPA's or ADEM'sResponses i This section presents the written commentssubmitted during the comment period and provides theEPA's responses to these comments.
IV. Remaining Concerns* This section discusses communityconcern that BPA should be aware of in design andimplementation of the remedial alternative for theSite.
I.The preferred remedial alternative was presented to the public ina fact sheet • titled -Clba-Geigy Superfund Site OD *4« Releasedon April 30, 1992. The recommended alternative addresses thesources of the contamination by treating the wastes in formerwaste management area #8 and the already selected, Operable Unitone remedy of continued extraction and treatment of groundwater.
The major components of the selected remedy for operable unitfour includei
Excavation of approximately 63,000 cubic yards ofcontaminated soils and sludges until established cleanuplevels are reached or until excavation limits are reached.
Solidification/stabilization of up to 46,000 cubic yards ofmoderately contaminated soils and sludge containing nogamma-BBC and less than 2,500 ppm total organica, as aninnovative application of this technology which may beproven effective during .the remedial design;Utilization of an innovative thermal technology ordechlorination if proven effective during the remedialdesign for treatment or pretreatment to LDR treatabilityvariances of contaminated soils;
On-site thermal treatment of approximately 17,000 cubicyards of highly contaminated soils and sludge and of wastenot amenable to final treatment using the innovativetechnology dechlorination or the innovative application ofsolidification/stabilization (up to 46,000 cubic yards);
Disposal of treated soil and residual ash from the thermaltreatment process in an on-site RCRA Minimum TechnologySubtitle C landvault(s);
In-situ stabilization/fixation treatment of approximately46,000 cubic yards of iron slurry waste;
In-situ soil flushing combined with isolation walls andextraction wells to remediate areas where the risk basedcleanup levels are not achieved before excavation isterminated. Innovative technologies (in-situ vacuumextraction or in-situ bioremedlation) may also be used inaddition to or instead of in-situ soil flushing, if duringthe remedial design either technology is found to beeffective in reducing contaminant concentrations in the soiland is cost effective. If either technology is proven to bemore effective than in-situ soil flushing in reducing theconcentrations of the contaminants in the soil and more cost
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effective, it will be used instead of in-situ soil fluahinaIf titter technology it not as effective as in-situ soilflushing in reducing the concentration of the contaminantsin th« toil it will not be utilized in place of in-situ soilflushing, however, it may be used in concert with in-«itusoil flushing if the combination enhances the remediation inreaching cleanup levels and is cost effective.
Issuing a public notice in a local newspaper and sending afact sheet to persons on the mailing list at the completionof the 30% design report. The purpose of the fact sheet andthe public notice would be to inform the public of thetechnologies selected that were proven effective during thetreatability studies conducted during the remedial design;Backfilling the excavated area with common fill, vegetatingthe area and the establishment of a suitable vegetativecover;Operation and maintenance of landvault(s) for a minimum ofthirty years; and
Institutional controls for land use and groundwater userestrictions.
II.The Mclntosh community has been aware of the contaminationproblem at the Ciba-Geigy Site for several years. EPAdistributed the first fact sheet to the public on August 30,1989. This fact sheet contained information pertaining to theupcoming Remedial Investigation (RI). EPA held a public meetingin Mclntosh Town Hall to discuss Operable Unit One withinterested citizens on September 13, 1989.
EPA and ADEM conducted the second public meeting on August 16,1990. The purpose of this meeting was to explain the results ofthe studies, to present the recommendation of EPA and ADEM forSite cleanup for operable unit #2 and to accept questions andcomments from the public on any aspect of the Site or itscleanup.Based on the cossnenta received on the August 1990 Proposed Plan,EPA issued and Amended Proposed Plan for operable unit #2 inFebruary 1991. BPA provided the opportunity for an additionalpublic meeting on February 20, 1991 upon written request to theAgency. A request to extend the comment period was received andgranted; however, no requests were received to conduct a publicmeeting.As a result of the written cossMnts received during the c<
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SI«,»..! S« JTOuS.iJJJiB i r£« i-« to th. kJ£. No
£STB js?s as « •
. hremedi.tion of Are. 8 .t the ctbi-dSi «PProach £or
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III.
The following is a summary of the written coaaents receivedduring the comment period for the Proposed Plan addresaing oo #4Comments1. Ciba-Geigy suggested that the term -effluent ditch- be
substituted for the phrase -lower portion of the diluteditch" throughout the document to be consistent with theterminology in the RI and the PS Reports.
Response sEPA agrees and will make the suggested aodlficationa infuture documenta.
Comment t2. Ciba-Geigy suggested that the words "the upland portion of
be deleted from the definition of Operable Unit #4 in theScope and Role of this Operable Unit in accordance withcomment 1•
Response sEPA agrees and will make the suggested change.
Comment s3. In reference to the Summary of Risk Assessment Section on
page 6, Ciba-Geigy suggested that to say that Area 8presents an imminent and substantial endangerment isexcessive and misleading.
Response sThe statement is based on the ingestion of groundwater whichis a potential future pathway. In evaluating this pathway,EPA cannot assume that the pump and treatment ay a tern will beoperating.
Comments4. Ciba-Geigy Indicated that it was not clear how the lxlO~*
Direct Contact Cleanup Levels would be used at the Site.
Responses.The Direct Contact Cleanup Levels will be applied to the toptwelve inches of .soil throughout the Site.
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COSMMAtS5. Ciba-Geigy suggested that the table on page 7 entitled
•Groundwater Cleanup Levels As Provided in ROD Addressina OD#1- includes a statement describing how the numbers apply tothe cleanup effort. "pp- y
Response sIn future documents the following note will be includediThe following groundwater cleanup goals will be applied atthe property boundary to ensure a IxlO"4 risk level forgroundwater leaving the site.
Commentt6. Ciba-Geigy indicated that a table comparable to the one in
the July 1991 Proposed Plan for OU #2 entitled "GmandwaterRemediation Levels kor De<ip Soil Treatment Areas" was notincluded in the Proposed Plan for OU #4.
Response tBPA has reviewed the comment and the table will be includedin the Record of Decision addressing OU #4.
Comment t7. In reference to the section entitled "Summary of
Alternatives" on page 9, at the end of paragraph 2,Application of Innovative Technologies To ExcavatedMaterials, a statement is made concerning "reducing theconcentrations of contaminated soil to LDR treatabilityvariance levels." Ciba-Geigy has submitted for EPA'sevaluation, a technical justification for an alternativemethod for determining treatment standards. The alternativeis discussed in a May 15, 1992 letter from Gary Payne toCharles King (RPM). Ciba-Geigy requested that the May 15,1992 letter be included as a part of Ciba-Geigy's commentson the Proposed Plan.
Response:Ciba-Geigy has recommended an alternative method fordetermining stabilization treatability standards formaterial that does not contain a RCRA waste. EPA hasconsidered the comment and will include performancestandards to evaluate the effectiveness ofstabilisation/solidification on the soils at the site.
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Commenti8. Ciba-Geigy has suggested that the word ••olid- be inserted
before -material" in the second line under paragraph 4 ofManagement Of Treatment Residuals And Pugaill Wastes. onpage 10.
ResponsesBPA agrees with the comment and will incorporate therecommendation into future documents.
Commentt9. Ciba-Geigy requested that the term "unleachable" in the last
sentence of paragraph 5 of In-Situ Remediation Process, onpage 10 be defined in the context of the discussion oftreatment standards in the May 15, 1992 letter to EPAreferenced in comment 7 above.
Response »BPA will modify future documents to clarify the meaning ofunleachable.
Commentt10. Ciba-Geigy requested that the May 15, 1992 letter offering,
an alternative method for determining stabilizationtreatability standards for material that does not contain aRCRA waste be considered in the discussion of Compliancewith ARARs which begins on page 10 and continues to page 11.
Response:EPA has considered the comment and will incorporate into theRecord of Decision where appropriate. See response tocomment number 7 above.
RESPONSES TO PUBLIC CONCERNS RECEIVED DURING THE PUBLIC MEETING
The following is a summary of the significant comments orconcerns expressed at the May 19, 1992 public meeting and EPA'aresponses.
Comments1. A concerned citisen asked if thermal treatment or
incineration would actually rid one hundred percent of thesedangerous materials.
Response sThermal treatment would not eliminate 100% of thecontaminants of concern, however; it would reduce the
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concentration* of the contaminant* of concern to BPA'slegislated treatment standards.
Comments__2. A coBBenter asked if a particular brand name of thermal
unit* would be used for heating or if a unit would bespecially designed for the Site.
Response tThere is not a particular brand name. During the RemedialDesign and Construction, the design criteria and type ofunit will be determined. If the three pretreatment optionsdo not work or if the treatability studies show that theyare not effective at reducing concentrations, then thebackup rotary kiln should definitely reduce theconcentrations to legislated treatment standards.
Commenti3. A conmenter asked where the rotary kiln would be located.Responset
The thermal treatment unit would be built on-site and Ciba-Geigy would submit their design to EPA indicating the typeof treatment system. BPA's experts in incinerator buildingwould carefully review their drawings, figures, and diagramsto ensure that this equipment meets the design standards andspecifications. When the equipment is built, contaminatedsoil samples in the area will be processed through theequipment during a trial burn to ensure that the equipmentwill achieve the desired standards.
Commenti4. An attendee at the public meeting asked if there would be
people working on-site while incineration would take place?Would the incinerator be located in a safe place?
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Response tThe operation would be conducted on-site. The exactlocation would be determined during the planning and desionphase which is about to begin. There would be peopleworking on-site during the incineration activity, therefore;a principal concern of the design would be to ensure thatthe air emissions from the unit would meet all state andfederal standards.
Comment:5. A citizen asked how air quality is monitored.Response:
Numerous parameters are monitored by continually takingsamples and analyzing stack gases.
Comment t6. A commenter asked if some systems have automatic shutdowns.Response »
They all do.
Comment t7. An attendee at the public meeting stated that the EPA could
hot say with 100% certainty that emissions that exceedfederal or state requirements would not be released into theair.
Response:Realizing that nothing is one-hundred percent safety proof,the equipment will be designed and built to ensure that nofederal or state requirements would be exceeded.Additionally, air emissions will be monitored to ensurecompliance with federal and state standards.
Comment t8. One commenter suggested that it might be cheaper and more
convenient to excavate and transport the material to ahazardous waste landfill.
ResponseiThere are advantages to on-site treatments because of thedifficulties in coordinating the logistics with thenecessary agencies due to the dangers associated withaccidents during the transport of contaminated materials. Inaddition, there is a preference under CSRCLA and the HOP foron-site and permanent treatment rather than off-sitedisposal.
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9. A concerned citisen stated that a company next door to Ciba-G01?y Hi** on-«ite atabilitation and it was a fiasco. Howwould IPX ensure that the stabilisation process would work?
ResponseiBefore on-site stabilisation would begin for the whole site,SPf"?! W T? ,*1*™ to demonstrate by treatability studiesthat the solidification process would work and would notleach at levels exceeding treatment standards.
Commenti10. A commenter asked if Area 8 had a four foot cap over it?Response:
It doe nc have an actual cap/ but approximately 4 ft^t ofuncontaminated soil has been placed over the area.
Commentt11. An attendee*at the public meeting asked if the contaminated
groundwater was leaching toward the Tombigbee.Response t
Because the groundwater is a potential threat, a pump andtreatment system is currently operating to mitigate thethreat. The groundwater pump and treatment system iseffectively capturing the contaminated groundwater before itmoves off-site and reducing the concentrations of thecontaminants of concern to within NPDES dischargerequirements. However/ if the source is treated as well, itshould reduce the amount of time that the pump and treatmentsystem will be required to operate to eliminate the threatof off-site migration of contaminated groundwater.
Comment t12. A commenter asked how close families could live to this type
of area.
ResponsesOf primary concern at the site is groundwater contamination,but the pump and treatment system that is currentlyoperating is effectively capturing the groundwater/ treatingit, end discharging it within permit requirements into theriver. Since the contaminants are not leaving the site atan unacceptable risk range, there is no reason not to livenear the site.
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ftntt13. A concerned citlsen asked when the first chemicals were
deposited in the ground.Responses
The majority of the chemicals were deposited in the late1950's and '60's.
Comment t14. A commenter asked if there are any groundwater monitoring
wells in the community?
Response:There is an extensive groundwater monitoring network on theCiba-Geigy and adjacent properties.
Comments15. An attendee at the public meeting asked if the contaminated
groundwater could have moved beyond these wells?Response s
No, the data shows that the hydraulic gradient has beenreversed and the contaminated groundwater is flowing towardthe pumping wells. The aquifer is being cleaned by the pumpand treatment system.
Comment s16. A commenter asked how the pump and treatment system reverses
the gradient.
Response sWhen the groundwater is removed from the aquifer, itsimultaneously creates a gradient toward the pumping wells.The wells act similar to a drain in a swimming pool.
Comments17. A commenter asked what treatment method is used in the pump
Comments18. A citisen requested the BPA representative to explain the
iron slurry treatment.
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Response!The Iron slurry treatment has been successful under the RCRAprogram in previous years. Treatability studies will beconducted to determine the type and ratio of mix needed toensure that the iron slurry is stabilized and will not leachinto the groundvater.
Commentt19. An attendee at the public meeting stated that Risk
Assessment only measures cases of cancer that may resultfrom particular carcinogens and suggested that BPA considerother impacts of chemicals on a system.
ResponseiAnother system, known as the Hazardous Quotient Index (HQ)is used to evaluate the noncancerous advere- effects ofchemicals. The IxlO"4 to IxlO'4 range for carcinogenic riskis a probability which is different from the HQ where knowndoses of a particular chemical will cause certain problems.
The HQ is found by measuring the level of a particularchemical found at the site and dividing it by the levelknown to have a harmful effect. If this is less that one,,then it is equivalent to a safe dose. If this fraction isgreater than or equal to one, then remediation is requiredto reduce the chemical concentration to a safe level.
The EPA also evaluates the effects of these chemicals on theenvironment and on animals at the site that may get into thefood chain.
Commenti20. A concerned citizen asked if a risk of one in ten thousand
to one in a million is acceptable for a project like this?
ResponseiThese are national EPA guidelines, hot for just thisproject.
Comments21. A cossesnter suggested that it should be left up to Ciba-
Geigy to determine the acceptable risk. How can thegovernment decide on an acceptable number of : Illnesses thatwill occur?
Response tUnder CBRCLA, it is BPA's responsibility to determine theacceptable risk. BPA has established nationally acceptable
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risk limit*/ but there it no way to completely eliminate thepossibility of cancer in this country. The SPA's approachis to improve the situation in a practical way by creatingfeasible target cleanup goals. This is the approach thatBPA hae developed to deal with situations like this.
22. A citizen asked if bio-remediation would work to clean upthe soils, in the same way that it is used to treatwastewater?
Response sHe will be looking at soil flushing for the soils belowtwenty feet. We will also do some treat ability studies onin-situ bio-remediation and vacuum extraction to see howeffective tl .. are in reducing the concentrations of thecontaminated soils. "In-situ* means treatment ofcontaminants in place without excavation.
Commenti23. An attendee at the public meeting requested the EPA
representative to explain these two in-situ technologies.
Response tIn-situ bio-remediation works by first placing particularnutrients in the soil, and then depositing specific bugswhich eat the contaminants.Under vacuum extraction, the contaminants are pulled orsucked from the deep soil.
Comment s24. A citizen asked if the vacuum extraction technology was
similar to using a vacuum cleaner.
Response:Tes.
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23. A coBB»nter asked if this is done down to twenty feet.Response t
It will be done below twenty feet.
26. A commenter asked if these technologies could be implementednear the aquifers.
Response tIf implemented near the aquifers, neither vacuum extractionnor bio-remediation would work. Ciba-Geigy would have toprove these technologies effective or soil flushing would berequired.
Comment s27. A concerned cltisen asked the BPA representative to describe
again how air quality is maintained with the incinerator.Response t
The incinerator would meet all state and federal governmentrequirements. It would not be allowed to release anychemicals into the air that a nonhasardous incinerator couldnot release. There would be a continuous monitoring devicethat would be designed to shut the incinerator offautomatically if contaminants exceeded state or federallimits.
Comments28. A commenter asked if the incinerator would be used to burn
nonhasardous waste after the cleanup would be completed?
Response sThe incinerator would be built specifically for the soils atthe Ciba-Geigy site. Our Consent Decree does not requireCiba-Geigy to apply for a permit with ADBM to burn soilsremediated under CBRCLA cleanup, but Ciba-Geigy would haveto meet all substantive requirements for incinerators in theState of Alabama. Additionally, Ciba-Geigy would have toapply for a permit with the State of Alabama to burn anyother waste.
Any comments that are not fully addressed at this time will beaddressed at the 30% design stage when the fact sheet is issued.
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main tbmrmal treatment process and/or cost effectiveness can beenhanced while still meeting levels as adjusted by the treatabilityvariance. Treatability studies would be conducted to determine if thecontaminated soils are amenable to treatment or pretreatment bydechlorination to treat the waste to LDR treatability variance levelsor to improve the performance of the Primary Treatment. These studiesmay also be used to determine if such treatment or pretreatment willimprove the performance of the solidification/stabilization of ofwastes containing no gamma-BBC or organic content less than 2500 ppn.Finally, treatability studies would be conducted to determine whethersolidification/stabilization might be an effective treatmenttechnology for soils containing no gamma-BHC and containing less than2,500 ppm total organics. This is an innovative application of thesolidification/stabilization process, if this technology is proveneffective, it will be used for these soils rather than the Primarytreatment.
3. Innovative Application of Solidification/Stabilization Technology
According to results from subsurface soil borings collected by Ciba-Geigy during RI/FS field activities, portions of Area 8 may containmanufactured pesticides that exceed the health-based cleanup levelsrequiring them to be excavated, but are not mixed with a RCRA waste.The manufactured pesticides of concern are toxicity characteristicanalytes and therefore have no toxicity characteristic regulatorylevels. Although no regulatory levels are exceeded for any toxicitycharacteristic analytes and it has been determined that the soil isnot a RCRA hazardous waste, these manufactured pesticides exceeded thehealth-based cleanup levels, requiring that they be excavated andtreated.All soils which are mixed with with a RCRA waste that exceed thecleanup levels will undergo thermal treatment or dechlorination and betreated to legislated (LOR) treatment standards, as adjusted by aCERCLA treatability variance upon signing of the ROD. Additionally,it is anticipated that it will be necessary to thermally treat some ofthe soil contaminated with manufactured pesticides that exceed thehealth-baaed levels which contain a total organic concentrations above2,500 ppm.
Soils containing less than 2,500 ppm total organics may be amenable totreatment using a .solidification/stabilization process. Thisapplication would represent an innovative application of thistechnology since EPA has minimal information on stabilization ofmanufactured pesticides. The NCP encourages the use of innovativetechnologies at Superfund sites. For this reason, and because this
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