POOR LEGIBILITY

ONE OR MORE PAGES IN THIS DOCUMENT ARE DIFFICULT TO READDUE TO THE QUALITY OF THE ORIGINAL

JFUND RECORDS CENTER88178094

Will < bW J I <1 I •

SFUND RECORDS CTR2970-02298

•OLIO WASTl ANO tMf MCINCY m

JUL I 7

MEMORANDUM

SUBJECT: Authorization to Proceed with Remedial Action for theStringfellow Site, California — Record of Decision

s^~~> fFROM: William N. Hedeaan, Jr., Directed fSiiVJOffice of Emergency and Remedial RfcidoTft

TO: Lee M. Thomas 'Ass-ist*nt Administrator- — -

The attached Record of Decision is presented for yourauthorization of remedial action at the subject site.

Me are asking your approval of the interim measure to instala treatment facility on-site to treat contaminated ground waterfrom on-site and the mid-canyon area. Treated effluent would betrucked to a local sewer line drop point for disposal. Effluentwould receive secondary treatment at the publicly-owned treatmentworks and then be discharged to the ocean. Sludge from thepretreatment process would be taken to a RCRA Class I land disposfacility.

Funding for design and some elements of construction isincluded in the PY 1984 Revised Remedial Accomplishments Plan.

Attachment

oocoe-s

UNITED STATES ENVIRONMENTAL PROTECTION AGENCYWASHINGTON. O.C. 204CO

or

TO: Ltt ThoaasAssistant AdainistratorOffiet of Solid Vastt and Catrgtncy

fctsponstFROM: Ufa K.

Associatt Ctntral coun«tlSolid Vaatt & Elstrgtncy Rttponae.piviiion_aE-132S) _

SUBJECT: Stringftllov Sitt • Rtcord of Dtcisionfor Fate Track RI/FS

V« have rtvievcd tht Fast Track rraedial invcacifaeion/feasibility study for tht Stringftllow Sitt. Vt art satisfitdthat it is consisttnt with tht National Contlnj«ncy Plan andraists no significant Itgtl issuts.

oceoc'j

WASHINGTON. O.C. 20*40

JUL ITMEMORANDUM

SUBJECT: Record of DeoilioMfor Approval of Reaedial Action at/"">bt Stringffijrow/>California Sitesfa4**t<'S r, ^..- -FROM: ifranfc Biros-/DimeterTechnical MvisionOffice of waste Programs Enforcement (WH-527)

TO: William N. Herman, Jr., Director——— ...Office of Eaergency and Reaedial Response (WH-548E)

The Record of Decision for the Stringfellov, California

Site has been reviewed by ay staff.

Z Concur

Z Do Not Concur

Z Concur With theAttached Conditions

Date

Comments:

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0*Tt Ally 13,

$U«J*CT Recommendation for an Interim Offsite Control Measure forStringfellow, Glen Avon, California

7 *"**-rWal Adm

John tfiseDeputy JfegrWal Administrator, Region 9 (DRA)

T0 Lee ThomasAssistant AdministratorOffice of Solid Waste and Emergency Response (WH-562A)

Eased on the Region's review of the Nay 18, 1984 report•Past Track Remedial Investigation/Feasibility Study, String-fellow Site*, and other available information, Z recommend thatinstallation of a pretreatment plant followed by discharge to aPublicly Owned Treatment Works system be selected as the interimoffsite control measure for the Stringfellow site. This alterna-tive will provide cost-effective management and disposal ofcontaminated groundwater to protect public health and the envi-ronment during the three to five year interim period prior tocompletion of the full-scale RZ/PS and implementation of thefinal remedy.

The California Department of Health Services concurs withthis recommendation* and a letter stating their concurrence willbe forwarded to your office within a few days.

Attachments

IP* ?•• 12304 <••». »«M» por.ni II/ w- w t. A. -L

TRecord of DecisionStringfellow, Glen Avon, California

Barcjf SeraydariaaDirector, Toxics 4 Wastt Manageaent Division (T-1)

TOJohn WiseDeputy Regional Adainistrator (DRA)

Attached for your review and signature is the cover ataoand documentation for our recoaaended alternative for an inttriaoffsitt control atasurt. at the Stringfellow site.

Based on the results of the Past Track Reaedial Znvestig*-tion/Ptasibility Study, tht Toxics and Waste Manageaent Divisionrecomaends installation of an onsite pretreataent plant for.removal of heavy metal and organic contaminants, followed by'discharge to a local Publicly Owned Treatment Works (POTW) system.Sludge from the treataent process will be deposited at a Class Ifacility. This alternative will be iapleaented during the threeto five year interia period prior to completion of the full-scaleRZ/PS and implementation of the final remedy.

Of the alternatives evaluated, this alternative is the lowestcost and provides the greatest protection to .public health, welfareand the environment. This alternative is supported by the ooaauaitof Glen Avon and the California Department of Bealth Services (DOBS

The Santa Ana Watershed Project Authority (SAWPA), a localPOTW, has submitted a proposal to DOBS for iapleaentation of therecoaatnded alternative. Zn anticipation of EPA's approval,DOBS has entered into a preliminary contract with SAWPA for thispurpose. DOBS is aware that CPA Bay not pay for any expensesincurred prior to selection of a reaedy through the Record ofDecision process.

Zn addition to the documentation of this recommendation, aIttttr of concurrence to bt signed by William Bedeman and theactual Record of Decision to be signed by Lee Thomas are includedin this package.

Zf you havt iny questions concerning this packet of aaterials,Z will be happy to meet with you at your request.Attachaents

CPA f~m 1IJ04 (*••. nom 2w «. - ^ *•

Record of DecisionRemedial Alternative Selection

SITE: Stringfellov Acid Pits, Glen Avon, California

DOCUMENTS REVIEWED Iv

My decision is based in part on review of the followingdocuments describing the analysis of cost-effectiveness ofremedial alternatives for the Stringfallow sitet

- Stringfellov Site Past Track Remedial Investigation/Feasibility Study, CB2N Bill. Hay 18, 1984

. summary of Remedial Alternative Selection- Responsiveness Summary- Final Draft Stringfellov Summary Report, Ecology andEnvironment Inc., Hay 16, 1984

DESCRIPTION OF SELECTED REMEDY

- Installation of an on-site pretrtatment system consistingof lime precipitation for heavy metals removal followedby.granular activated carbon treatment for organics removal.Fretreatment vill be folloved by discharge to a publiclyowned treatment works (FOTW) system

- Operation requirements includes Chemical and carbonreplacement, monitoring, electricity, labor, transportationof treated effluent to a FOTW sewer drop point and disposalof contaminated sludge at a Class I facility.

- Installation of additional interceptor and monitoring wellsto extract contaminated groundwater downgradient of the site

DECLARATIOMS

Consistent with the Comprehensive Environmental Response,Compensation, and Liability Act of 1980 (CERCLA), and theNational Contingency Flan (40 CFR Fart 300), I have determinedthat the installation of a pretreatment system at the Stringfellovsite it a cost-effective interim measure and provides adequateprotection of public health, welfare and the environment. TheState of California has been consulted and agrees with the approveremedy. In addition, the action vill require operation activitiesto ensure the continued effectiveness of the remedy. Theseactivities vill be considered part of the approved action andeligible for Trust Fund monies until Implementation of theremedial action for final site closure. The state vill applyfor operation funds on an annual basis.

OOC013

I have also determined that the action being taken isappropriate when balanced against tha availability of TrustFund aonies for use at other sites. In addition, the off.sitetransport of-sludge and pretreated effluent is aore cost-tfftctivcthan other reaedial actions, and is necessary to protect publichealth, welfare, or the environaent.

The State of California is currently conducting a full-scale Reaedial Investigation/Feasibility Study to identify andevaluate aethoda to prevent or aanage upstreaa groundvater andsurface water entering the site, to prevent aigration of hazardoussubstance off-site, to define aquifer characteristics, the extentof the contaainant pluae, and aethods of controlling aigration.A cost-effective reaedial action for final site closure will bedeveloped. If additional raaedial actions are determined to benecessary, a Record of Decision will be prepared for approval offuture reaedial actiona.

/ Date Lee M. ThoaasAssistant Adainistrator

Office of Solid Kaste and Baergency Response

COCO14

SUMMARY OF REMEDIAL ALTERNATIVE SELECTION

STRINGFELLOW ACID PITSGltn Avon, California

SITE LOCATION AND DESCRIPTION

The Stringfellow site is located in Riverside County, Approx-imately five miles northwest of the City of Riverside and one•die north of the community of Glen Avon. The site is locatedat the head of Pyrite Canyon which lies in the southern portionof the Jurupa Mountains, approximately 4,500 feet north of theintersection of U.S. Highway €0 and Pyrite Street. The canyonopens into the town of Glen Avon* south of U.S. Highway 60.(See Figure 1.)

The watershed_jure4K£rjibgtarxn:to tnt disposal site is approxi-mately 270 acres.' Groundwater beneath the site moves in a seal-confined aquifer bounded by canyon walls to the north, east andw«st. Water flows toward the south, exiting the canyon justnorth of Highway 60 and then enters the Chine lasin regionalgroundwater system which travels toward the southwest. TheChino Basin system provides a domestic drinking water supplyfor approximately 40,000 potentially affected residents. Thegroundwater supply is also used for industrial and agriculturalpurposes. Surface runoff from the canyon move's southwesterlyfrom the site and collects in a culvert drop box just north ofHighway 60. Surface runoff then flows under the highway throughGlen Avon in lined and unlined channels, and eventually to theSanta Ana River, a total distance of approximately 7 miles.The site is surrounded by undeveloped land which is primarilyused as range land. An operating quarry is located about aquarter of a mile downgradient of the site on the western sideof the canyon.SITE HISTORY

The site was operated by the Stringftllow Quarry Company fromAugust 21, 19S6 to November 19, 1972 as a hazardous waste disposalfacility permitted by the Santa Ana Regional Water Quality ControlBoard (WQCS). Approximately 34 million gallons of industrialwastes, primarily roa metal finishing, electroplating and DOTproduction* were deposited in evaporation ponds on the site.Site operations also included spray evaporation of pond contentsto accelerate volume reduction. The total disposal area wasapproximately 17 acres. The site was voluntarily closed in 1972.

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In 1969 and 1978, axetaaiva rainfall cauaad tha disposal pondsto ovarfloW.. Tha overflowa axtandad south of Highway €0 intoClan Avon. In 1980 and 1981, tha RWQCB iaplementad an IntarimAbatement Program at tha diapoaal aita aa tha firat phaaa of sitecloaura. Tha progran includad removal of all aurfaca liquids,partial neutralization and capping of tha waatea, installationof a graval drain and a network of «xtraction, intarcaptor and•onitoring walla onaite and downgradiant of tha aita, diversionof aurfaca water around tha aita via gunita channela, and con-atruction of a clay eora barriar dam and laachata eolacton systemdowngradiant of tha diapoaal ponds to atop migration of aubaurfacalaachata.

For a Bora datailad daacription of pravioua raaponaa aetionaand anforcaaant activities, plaaaa rafar to tha July 22* 1983Stringfallow Record of Daciaion briafing documents. Tha followingparagraphs daacriba tha raaponaa aetiona parforaad ainca Hay,1983. EnforcamanT'actWrrVaT"ail'diacuaaad in datail in tha —Cnforcaaant aaction.State-lead ActivitiesA $2.8 Billion cooperative agreement waa awarded to tha Stata ofCalifornia on July 28, 1983, and a $7.1 Billion Amendment waaawardad on December 28, 1983 for tha Stringfallow aita. Activitiesfunded include initial raaadial measures (IRK),- interim aoureacontrol maaauraa, interim offaita control measures, a remedialinvaatigation/faaaibility atudy (HI/PS) and reimbursement forInterim Abatement Program activitiaa.Initial remedial measures fundad undar tha cooperative agreementinclude erosion control and fancing. Croaion control measureswara completed in November 1983, and a fanca will be constructedaround tha aita in August, 1984.

Interim aourea control measures ineluda extraction and offaitadiapoaal of contaminated groundwater. Groundwatar ia pumped fromaxtraction faeilitiaa and routed to a aariaa of holding tanka.It ia than tranafarad to trucka for transport to a Claaa I diapoaalaita. Sinca July, 1983, groundwatar has been axtraetad fromthree onaita walla (OW-1, OH-2, OW-4) and two downgradiant aourcaa(tha franch drain and XN-1) in order to Intareapt tha flow ofcontaminated groundwatar from tha diapoaal araa and to preventthair migration down tha canyon, letween July, 1983 and March,1984. approximately 150,000 gallons of groundwatar waa axtraetadpar waak.

• •

On lurch 23, 1984, EFA leadquartera authorized axtraction anddiapoaal of groundwatar froa two aid-canyon walla (XW-2 andIW-3). Sinca that time, a total of approximately 200,000 gallonspar waak of groundwatar has been axtraetad froa tha onaitaand downgradiant faeilitiaa.

000016 •

JRB Associates was selected by the California Department ofHealth Services (OOHS) to conduct the RI/FS. The contract wassigned on March 26, 1984. The study is scheduled to be completedon October IS* 1985. The RI/FS will recoaaend a cost-effectiveremedy for final site closure.CPA-lead Activities

To assist the State prior to con&enceaent of the RI/FS andother cooperative agreement activities, and for the purpose ofenforcement support. CPA has undertaken the following activitiessince April, 1983i emergency response actions, monthly samplingprogram, electro-magnetic conductivity survey, installation ofnew aonitoring wells, the Fast Track RI/FS, treatability studiesand pilot tests of the mid-canyon extraction well field. TheFast Track study is the basis for this Record of Decision, inaddition, CPA has entered into an Xnteragency Agreement with theOS Any Corps of -Bng-fcfie»r«M-uSACC^»The USAGE will providetechnical assistance during Remedial Design and the full-scaleRI/FS.• Caerqency Response» In May, 1983, contaminated liquid wasdiscovered surfacing several hundred yards below the barrierdam. The contaminated liquid mixed with surface water whichis channeled around the sits. DOBS authorised constructionof an open pit to collect leaehate and pumping of contaminatedliquids to onsits holding tanks. Contaminated liquid wasdisposed of offsite together with the extracted groundwaterdescribed previously.Xn Hay, 1983, DORS requested CPA assistance for containmentaction. Between Hay and November, 1983, R*gion 9's Biergency

. Response Team with assistance from the OSCC Pacific StrikeTeam performed the following activities: installation of afrench drain in the seepage area with a sump to collectliquids and automatically pump liquids to the holding tanks,improvement of drainage channels consisting of grading,trenching and paving, installation of an upgradient spring boxand installation of upgradient 'pump barrel* sumps to collectand divert uncontaminated groundwater around the site.

• Monthly Sampling Program t CPA'a contractor, ecology and environ-meat (C ft I)» conducted monthly groundwater sampling of extrac-tion, interception, monitoring, and private wells from Aprilthrough September and November, 1983.

*

• Clectro-maqnetic Conductivity Surveyt Xn June, 1983* C a Cconducted an electro-magnetic (CM) conductivity survey todelineate areas of high ionic concentration in groundwater

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which may be related to inorganic contamination. The surveyresults- indicated that the extent of the groundwater contam-ination plume may not have been detected by the existingmonitoring veils. E t E recommended the installation of 4new monitoring wells to confirm the results of the EM survey.

- New Monitoring Wells; During September and October, 1983,C & £ installed 4 monitoring wells in the lower Pyrit* Canyonarea based on the CM survey.

- Past Track Rl/PSt The State requested that an EPA-lead Past-Traefc JU/FS be conducted to identify and'evaluate alternativesto current groundwater extraction and offsite disposal opera-tions. Originally, this activity was included as Tasks ZXand X in the full-scale RZ/PS funded under the cooperativeagreement. The selected alternative, or interim measure,would be implemented during the 3-5 year period prior to'completion of the full-scale RX/FS^and-implementation of thefinal remedy. This activity, conducted by CB2M Bill, wasintiated in September, 1983. The final report, issued on May18, 1984, is the basis of this Record of Decision.

- Treatability Studies: Since June 4, 1984, CB2H Bill hasperformed laboratory characterisation and treatability testingon Stringfellow water to verify the capability of the pretreat-ment system recommended in the Past Track report to meetpretreatment objectives, and to confirm operating cost estimates.

- Pilot Pumping Testt Zn early July, 1984, CB2M Bill performedpilot tests of the mid-canyon groundwater interception wellsystem to verify the long-term pumping rate required to effec-tively intercept contaminated groundwater moving through themid-canyon area.

CURRENT SZTE STATUS

Hazardous Substances PresentTable 1 presents a summary of the concentration ranges formajor contaminants present in the groundwater at the Stringfellowsite. Analytical results for upgradient water are from springwater samples collected north of the disposal areai this is anindicator of background levels of groundwater constituents inPyrite Canyon. • ~High concentrations of heavy metals present in the contaminatedgroundwater found onsite include chromium, cadmium.,' copper andsine. Zn samples collected from onsitt wells, nitrate* sulfateand chloride level! art one to two orders of magnitude higherthan background samples. Onsite water ranges in pB from 2.6 to4.1, significantly more acidic than upgradient water (pi 7.0 to7.2). A wide range of organic pollutants are present in the

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000019

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onsite and- dovngradient groundwater. The organic pollutants inthe greatest-concentrations are 1,2-dichlorobenzene, isopborone,aethylene chloride* trichloroethylene (TCE), chloroform, acetone2-butanone» and 4-aethyl-2-pentanone. Traces of pesticides(4,4'-DOT and 4.4*-DDE) are also present.

V

Recent analytical work performed by the National EnforcementInvestigation Center (NEXC) has revealed chlorobenzenes~ulfonicacid (CBSA) as a contaminant in the groundwater at Stringfellow.Analysis for this substance had not been performed previouslybecause it it not a priority pollutant. Concentrations of CBSAwere as high as 2000 ag/1 in samples taken froa onsite wells.CBSA is an industrial byproduct of DOT production and is usuallyfound in the sulfuric acid wastes from this process. Relativelylittle toxicological data exists for CBSA and an analyticalprotocol is being developed. Analysis for CBSA-will be includedin the next Monthly saapling effort. , _ .-_.. .. .NEXC's analysis also revealed gross alpha radiation levels rangingfroa 38 to <72 picbcuries/llter in saapes take from onsite wellsand IW-2 and XW-3 (see Figure 2). To follow-up on these findings,DOBS is conducting saapling of upgradient* en-site* downgradientand Glen Avon coaaunity wells to determine the extent and sourceof radiation contamination. Two hundred and twenty-six sampleshave been taken following a door-to-door canvass of liOO residencesand businesses in Glen Avon to locate wells*On June 11 and 12* 1984* samples were taken froa three largewater purveyors in Glen Avon. Radiation analyses conducted bythe Departaent's Sanitation and Radiation Laboratory show thatthe water delivered by these systems aeets the State and Federaldrinking water standards for radioactivity. Results of analysesperformed on saaples froa 14 doaestic wells taken the week ofJune 6, 1984* show gross alpha activity ranging froa negligible to31.3 picocuries per liter. Two of these domestic wells are incompliance with Federal drinking water standards for gross alpharadiation? further analysis must be conducted on the other twelvesamples.

As a precautionary measure until the sampling and analysis iscomplete, DOES is providing bottled water to approximately 300Glen Avon households who normally obtain their drinking waterfroa privatt wells or froa the small public water purveyor*Felspar Gardens Mutual Water Company. Bottled water is beingpaid for through emergency provisions of the State's Superfundprograx.

ooeo^o

Extent of Contamination

Information on groundwater quality consists primarily ofanalytical results from samples colltcttd by E i C during1983. Samples war* collected from 3 extraction wells (OW-i,OW-2, OW-4), 3 interceptor wells (JW-1, IW-2, IW-3), 18 dovn-gradient monitoring wells, and private wella in the communityof Glen Avon. (Refer to Figures 1 and 2.)

A report issued by E & E in May, 1984, concludes:- TCE is the primary organic contaminant present in groundwaterdowngradient of the disposal area. Organic contaminantsother than TCE and chloroform have attenuated significantlybefore reaching lower Pyrite Canyon.

- Downgradient migration of significant quantities of m«tala isconfined to the upper-and mid-Pyrite Canyon areas (approxi.*——..•ately 1,200 feet offsite).

- Sulfates and chlorides have migrated to the lower canyon area.Mo contamination related to the disposal site has been detectedin any of the private wells included in the monitoring program.

- The main axis of the contaminant plume appears to run alongthe eastern side of lower Pyrite Canyon past HH-15B and MU-17B.

- Data concerning vertical stratification of contaminationsuggests that contamination is distributed throughout theaquifer thickness.

The full-scale RX/FS will obtain information necessary tobetter define the potential areal and vertical extent of thegroundwater contaminant plume.

Pathways of MigrationInterpretation of the EM conductivity survey suggests that plumemovement is strongly controlled by the location of buriedchannels in the alluvium.Alluvium is probably the main water-bearing material in PyriteCanyon. The alluvium is permeable and varies in thicknessfrom 10 feet at ttav south end of the site to 10 feet at themouth of the canyon. The alluvium in the lower parts of thecanyon is made up of distinct layers of clsy, sand and gravelas opposed to its more heterogeneous nature in upper parts ofthe canyon. Older alluvium rests on the weathered bedrocksurface and consists primarily of dense sand with gravel andboulders of highly weathered granodiorite.

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No information is available on the water-bearing characteristicsof the weathered, fractured, and jointed bedrock, but watercould b« contained within theae features, and, if inter-connectedthese features may transmit water for certain distances-. Adetailed investigation of alluvium and bedrock pathways of•igration will be conducted in the full-scale RI/FS.The depth to groundwater ranges from 10 to 40 feet. Ground-water velocity rangea froo 50-3,500 ft/year depending on location.Velocity is lowest in the silty, clayey sedinents near the canyonwalls and highest in the central portion of the valley. Theaverage groundwater velocity is estimated to be about 1,200ft/yr. In the mid-canyon area, average groundwater under-flow is estimated to 40 gpm.

Potential receptors

Numerous private wells are located downgradient of the site. "'In a recent survey of the private wells in Glen Avon, over 200private wells were located directly downgradient of the site.Groundwater exiting the canyon mixes with the Chino Basin aquiferwhich provides a domestic drinking water supply for approximately40,000 potentially affected residents and is used for industrialand agricultural purposes.

Exposure Potential

Section 300.68(e) of the National Contingency Plan (NCP) directsthat the extent to which contaaination poses a danger to publichealth, welfare, or the environment be assessed in order todetermine the appropriateness of proposed remedial actions. Inorder to comply with this requirement, an endangerment assessmentof the groundwater conditions in the vicinity of XW-2 and IW-3was conducted to determine the extent to which contaminationposes a danger to public health, welfare or the environment.The endangerment assessment addressed the likelihood thatcontaminated groundwater will reach downgradient domestic wellswithin the next three years. This is the minimum time anticipatedbefore final remedies can be implemented.For the purpose of the endangerment assessment, • key constituent!were Identifiedi trichloroethylene (TCE), chloroform, cadmium,chromium, s* thylea* chloride, isophorone, lead, and nitrate.Because TCC and chloroform are mobile in the groundwater environ-ment, they present the greatest immediate danger to downgradientgroundwater users. Their presence has been verified 4*000 feet•outh of the disposal area.Monitoring veil data shows TCE levels consistently above theCalifornia action level of 5 ug/1 and CFA's 10** Meter QualityCriteria of 2.7 ug/1. Chloroform has been found at levelsconsistently above-the State action level of 2 ug/1 and EPA's10-t tfcter Quality Criteria of 0.19 ug/1 in all but one well.

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The highest average values found of TCE and chloroform are1*600 ug/1 and 230 ug/1, respectively.

TCC is a halogenated hydrocarbon of relatively low acute toxicity,but in high doses can cause central nervous system depression,long-term neurological effects* dermatitis, and peripheralneuropathies. Liver toxicity has been observed in high doseanimal studies and in humans at anesthetic doses. The-statusof TCE as a potential human carcinogen is not fully resolved,but is a proven animal carcinogen. Chloroform can cause nausea,dizziness, and acute central nervous system depression. Chloro-form can also cause chronic liver and kidney damage.

Heavy metal contamination can cause damage to the centralnervous system, liver, kidneys, gastrointestinal tract andrespiratory tract. Some of the heavy metals identified for thehave .beeiu.found to be carcinogenic, teratoc,enic and/or mutagenic.

Calculations of contaminant movement were made in the endanger-ment assessment. Based on anticipated dilution effects, itis estimated that in 2.5 years the levels of TCE in the areaof the nearest domestic well (3,200 feet downgradient from IW-2and IW-3) could be between ISO and 100 ug/1 and the levels ofchloroform could be between 20 and 110 ug/1. These levels aremuch higher than the action levels» therefore, it was concludedthat a significant threat to public health exists due to •ground-water contamination from the site.

•

The results of the endangerment assessment show the need forinterim extraction of contaminated groundwater from mid-canyonprior to completion of the full-scale RX/FS and implementationof the final remedy. This interim measure will effectivelyprevent migration of contaminants toward domestic wells down-gradient of the site and will thereby abate the threat topublic health.A comprehensive health assessment is currently being conductedby DOBS and a more comprehensive endangerment assessment maybe performed during the full-scale RX/PS.

CNFOKCEHglTr

Potentially ResponsJble parties (»RP)In August and October, 1982, ETA issued over 200 combinationCERCLA section 104/RCRA section 3007 Notice Utters to potentiallyresponsible parties. The government negotiation team whichconsists of EPA, DO*S, the United States Department of Justice(DOJ)f and the State of California Attorney General held ageneral meeting with potentially responsible parties in ttovember,1982. The purpose of this meeting was to initiate enforcementdiscussions with potentially responsible parties to recover past

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and futurt costs of cleanup. On April 21* 1983* the UnitedStates ahtf the State of California filed a civil suit in theUnited States District Court for the Central District ofCalifornia. Eighteen generators* 4 transporters, and 9owner/operaters were named as defendants in the lawsuit.

v»

A record of disposal activities at the Stringfellow site existsin 35*000 pages of Stringfellow business records. NCX€ has hadthis information put into a computer data base and is able togenerate summaries of the information.

Litigation Status

- DiscoveryThe case is presently in the discovery phase of litigation.Both the defendants and the plaintiffs have* and continueto, produce""ddcttaenti> propound interrogatories* and conductdepositions. Additionally, the plaintiffs have served requestsfor admissions on defendants; these requests are for admissionthat the Stringfellow business records are genuine and admiss-ible documents.

- SettlementZn Octoberr 1983, the United States presented two settlementoptions to defendants. Option 1 would allow the potentiallyresponsible parties to perform the RX/FS and to implement theresulting remedial actions, both under the supervision of EPAand the State. Option 2 would allow EPA and the State toperform the RI/FS and to implement the resulting remedialactions: the defendants would pay 100% of the cost. Thedefendants settlement negotiations. CPA has offered to return*settlement discussions at any time convenient to the defendants

- Motions

Judge Malcolm Lucas issued his ruling on the issue of Jointand Several Liability on April €, 1984. The ruling grantsJoint and Several under CCRCLA $107, but needs further clari-fication en the applicability of Joint and Several underCERCLA HOC.

As with the ruling en Joint and Several Liability, the rulingon Retreactivity will need further clarification before a full'understanding of its implications is realised. ••e

The motion for intervention, submitted by members of thecommunity, was granted as permissive intervention withconditions. The appeal en this ruling was denied by thecourt.

noon d•• fc •• - *w —

- No Action

Aa require* "by Stction 300.68 (e) of tht NCP, an aaaessatntof the groundvatar eonditiona waa conducted to determine th«•xttnt to which continued migration of groundwater contaaina-tion poaea a threat to public health, welfare* or the'enviton-•ent. The endangerment assessment addreaaed the likelihoodthat contaminated groundwater will reach downgradient domesticwalla within the next three yeara. Thia ia the minimum timeanticipated before a final remedy can be implemented. Baaedon findings of the endangenaent assessment, it waa concludedthat a aignificant threat to public health from migration ofcontaminated groundwater would exiat within 2.5 yeara if nointerim action were taken. (Refer to pagea 7 and 8 for adiscussion of public health concerna.) Therefore, the•no-action* alternative waa eliminated from furtherconaideration.

- Discharge to a -PubHcly Owned Treatment Works WithoutPretreatment

Two POTW systems were identified aa tentatively auitable forreceiving extracted groundwater. Each POTW haa water qualitylimitationa for industrial waatea discharged to ita ayatem.Because untreated Strihgfallow water exceeda the water qualitylimitationa of both ay stems and could not be diacharged toeither without pretreatment, this alternative waa eliminated.

- Reinjection Without Treatment

Geologic and hydrogeologic data required for implementationof this alternative ia unavailable at this time. Aquifercharacteriatica will be fully atudied in the full-seal* RI/FSand thia alternative may be reconaidered at that time.However* without adequate knowledge of the hydrogeology ofthe area, reinjection could actually accelerate migration ofcontaminated groundwater. Therefore, thia alternative iaunacceptable at thia time.

- Treatment followed by Heinjection

Aa with the alternative, •Reinjection without Treatment*,extensive geologic and hydrogeologic information is required inorder to assess 4he impacts of this alternative. Thia informa-tion is not currently available. Thia alternative may be recon-sidered in the full-scale HI/PS but is unacceptable at this time,

- Solar EvaporationMo suitable land area was identified. Establishment of surfaceimpoundments for solar evaporation either in Fyrite Canyon orelsewhere in the vicinity was judged to be unacceptable to thaeurrounding community. It ahould be noted the exiatence of the

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Stringfellow sit* as an uncontrolled hazardous waste site isdut to a failed attempt at solar evaporation. Community andlocal agency opposition to a second attempt at onsitt solarevaporation was anticipated to be strong and could precludetimely implementation of this alternative.

- Incineration

CPA is unaware of any suitable incineration facilities in closeproximity to the site, thus a facility would have to be con-structed onsite. Since prefabracated components for this typeof facility are not available, the extensive time requirementsfor design and construction render this alternative inappropri-ate as an interim solution. Due to the complexity of thistype of facility, the capital costs of construction would behigh; due to the low heating value of water, energy costsjwould be prohibitively expensive.

- Surface discharge

Surface discharge of extracted contaminated ground water couldcause extensive surface water and soil contamination and wouldviolate existing water quality criteria. This alternative maynot mitigate the current ground water problem table resultingin even further migration of the contaminant plume. In addition,it presents a threat to public health as a result of consumptionof or direct contact with contaminated water.

- Treatment followed bv Surface Discharge

A pretreatment facility would be built on-site. Treated efflu-ent would be discharged to Pyrite Creek which flows throughthe community of Glen Avon in lined and unlined channels tothe Santa Ana River. This alternative would require extensiveremoval of contaminants to meet existing water quality criteriadue to the low dilution capacity of Pyrite Creek. The costsassociated with this level of treatment would be high. In theevent of a treatment system failure, a release of contaminatedwater could result in surface water and soil contamination,and could create a potential threat to public health due tovolatilisation of organics and the potential for consumptionof or direct contact with contaminated water.

- Disposal at a Permitted Batardous isiste Treatment facility

There is one permitted hazardous waste treatment facility insouthern California. Treatment at the facility consists of

000027

-13-

neutralization, settling, and sludgt dewatering. Dev«ttredaludga is disposed of onsitt and treated effluent is dischargedto an industrial sever which connects to a POTW. The facility'streatment process for contaminated groundwater from the string-fellow site Bay not produce an effluent which would complywith the POTW pretreatment standards since the process is notdesigned to remove organic contaminants. Moreover, "the facilitylimited capacity and current customer loading makes it inadequat<for expected Stringfellow quantities.

- Reuse as Industrial Process Hater

Demand for contaminated water in industrial facilities islimited. CPA is unaware of any industrial facility in closeproximity to the site that could use contaminated water, inaddition, this alternative may present a public health hazarddue to the. potential for employee exposure..to .volatile emissionsfrom the contaminated water. Furthermore, a potential existsfor mishandling the contaminated wastewater after it has beenused as process water. Thus, this alternative may present athreat to public health and the environment.

- future Treatment of Drinking Kiter at the Tap

This alternative does not achieve the remedial objectives ofpreventing the migration of additional contaminated groundwater,thus the entire Chino Basin aquifer may ultimately be contaminatAs a result, an expanded tap water treatment program would berequired. This alternative would not alleviate environmentalproblems and may worsen long-term problems by allowing furthercontamination of the groundwater basin.

Detailed Description of Remaining Alternatives

The remaining alternatives were evaluated regarding theireffectiveness in meeting the remedial objectives of the Past-Track XI/PS and on the baais of cost. In addition to operationof the existing facilities, as proposed in the Past Track, thefollowing components are common to all three of the remainingalternatives:

- Storage Tanks and Containment StructureIn order to effectively intercept contaminated groundwaterin tht mid-canyon, the Past Track determined that groundwatershould be extracted at an average rate of 40 gpm. An additional200,000 gallons of onsite storage capacity is needed to acctdate the total flow. This will provide 3 days of storagecapacity. In addition, it is necessary to install a concretecontainment structure around the storage tanks to preventflow of contaminated water down the canyon in the event of aspill and to divert storm runoff from the storage tank area.Design and construction of storage tanks and a containment

POP-,-,-3^ «/ «* w »«

- Gunite Channels

in order to'alleviate the existing surface water runoff andsoil erosion problems, tht existing eastern and westerngunite channels should be extended. Specifically, tht easternchannel should be extended past the Baker tanks and a culvtrtshould be installed beneath the road to carry runoff, thewestern channel should be extended to connect with flowsfrom the east prior to discharge to Pyrite Creek. (See Figure2.) extension of the gunite channels and installation of aculvert is estiaated to cost $110,000.

- Piping

The piping for conveying flow fron the spring upgradient ofthe site to the eastern gunite channel is danaged and caustsa surface runoff and infiltration problem. A permanentconveyance consisting of new piping extending all the way tothe channel is required-.—(See Figure 2.) The estiaated cos.£___of this conponent is 13,500.

- Interceptor and Monitoring ttells

Additional interceptor and monitoring wells are required toassure effective interception of contaminated groundwater inthe aid-canyon area. The estimated cost of this component is$110,000.

A description of the three remaining alternatives follows:- Alternative It Pretreataent followed by Discharge to a POTW

A pretreatment facility would be constructed at the Stringfellowsite. The treated effluent would be trucked to a local POTWsystem drop point for discharge effluent would receive secondarytreataent at the POTW. The sludge would be disposed of at aClass I facility. The POTW system which receives the pretreatedwater would establish the level of pretreataent through theissuance of a discharge permit.The Los Angeles County Sanitation District (LACSD) and theCounty Sanitation Districts of Orange County (CSDOC) wereidentified as candidates for disposal of pretreated Stringfellowwater because th*y have aarine discharge points and system droppoints close to the site (less than IS ailes).The CMno Basin Municipal Water District (CBKWD), whichdischarges to the LACSD, and the Santa Ana Watershed ProjectAuthority (SAWPA), which discharges to the CSDOC, have estab-lished discharge requirements. Contaminated water at thesits bears similarities to metal finishing industry wastewater.

-13-

containing both heavy metals and organic solvents, in absenceof categorical treataent requireaents* the most stringentrequireaents of CBMWD* CSDOC* SAWPA and EPA PSNS (pratreataentstandards for new sources) were set as goals to be met bythe recoaaended alternative. Table 2 summarizes these pre-traataent objectives. v:

Before this alternative could be fully evaluated and-costestiaates prepared* a review of treataent technologies wasconducted to determine the optiaal pretreataent process forStringfellow groundwater. Based on the types and locationsof contaainants preaent at the site* two basic treataentoperations would be required to aatisfy the discharge objec-tives identified. These operations are heavy aetals removaland organics reaoval.

The basic technologies for reaoval of haavy metals areprecipitation"*nd~ Concentration. The following treataentprocesses were evaluated! alkaline precipitation* aulfideprecipitation*.ion exchange and reverse osaosis. The followingorganics removal treatment technologies were evaluated:stripping, oxidation* adsorption, solvent extraction andaeabrane separation.Based on an analysis of coaplexity of operation* probabilityof achieving desired reaoval* relative capital coats* relativeoperation and aaintenance costs* potential operating problems*and types and potential volumes of residues generated* itwas determined that the most effective system for treatingStringfellow groundwater would consist of lime precipitationfor haavy metals removal followed by granular activatedcarbon treataent for organics reaoval. (For a discussion ofthe different treataent technologies* refer to the FinalFast Track RI/FS.) Thus* this systea was used aa a basis forevaluating this alternative.

- Alternative 2: Disposal at a Class I Land Disposal Site

The current practice of hauling extracted groundwatar toa Class Z disposal site would be continued. Class I disposal•ites an State-licensed facilities permitted to accept thebroadest categories of hazardous wastes. Stringfellow ground-water is currently disposed of at the Casaalia Resources* Inc.facility la SahCl Barbara County* • distance of about 210

. siiles frost the Stringfellow site.•

• Alternative 3» Disposal at « Class II-l Land Disposal SiteExtracted groundwater would be disposed at a Class II-ldisposal sits. Class II-l land disposal sites are State-licensed facilities permitted to accept preacribed quantitiesof specified waste types. Proa a list of all of the II-l

•facilities in California, only two sites have been identifiedaa potentially suitable sites based on capacity* and typea of

- oooo:;u

TABLE 2

PROPOSED PRETREATMCNT OBJECTIVES

Constituent

ArsenicCadmiumChromium (T)CopperLeadMercuryNickelSilverZincCyanide (Total) •—Cyanide (Amenable)PCB's & PesticidesTotal Toxic OrganicsSulfide (Total)Sulfide (Dissolved)Oil or GreaseBODCODTSSPH

Maximum Cone, (mg/i)

20.110.520.690.033.980.432.611.2010.020.5850.5100250

• 50003006-9 (pH units)

-16-

waste accepted. These facilities are operated by EnvironmentalProtection-Corporation (EPC). Facilities at both sites consistof lined surface impoundments for solar evaporation. Remainingsolids and sludges are landfilled in a lined disposal area.These facilities are approximately 170 miles from the Stringfellowsite.

Detailed Evaluation of Alternatives

The effectiveness of these alternatives was evaluated on the basisof cost, public acceptability, public health, environmental andtechnical considerations. Eight criteria were developed to evalu-ate these factors:

- Time; How much time is required to implement the alternative?

-. Compatibility; Can the alte_rnati_ve be easily adapted to thefinal remedy to be identified"" in thYTulT-s"cale RI/FS (i.e.1,could it be modified or discontinued easily)?

- Reliability/Risk of Failure; How reliable would the alternativebe based on the operating characteristics of the processes andequipment involved? This criterion applies to the technologystatus of processes used onsite and at the receiving facility.

- Level of Site Cleanup; To what degree will*the alternativeachieve site cleanup?

- Community Impact; Will the alternative have an acceptable effecton the residents of Glen Avon and other potentially affectedcommunities?

- Technology Status; Is the technology well-established or experi-mental? This criterion applies to the technology status ofprocesses used on-site and at the receiving facility.

- Potential Environmental Impacts: What environmental impacts,either positive or negative, would be expected to result fromthe alternative? This criterion applies to the potentialenvironmental impacts as a result of operations at the site,during transport and at the site of ultimate disposal.

- Complexity of Operation: Bow difficult would it be to operatethe components of the alternative? This criterion applies tothe complexity of operations at the site and at the receiving

* facility.- Cost; Annual and total three-year cost estimates were developed

for each of the three alternatives because the selected alterna-tive will be used on an interim basis until a final remedy isimplemented.

000012

-17-

A summary effectiveness evaluation and estimated cost for eachalternative is presented in Table 3. A comparative evaluation ofthe alternatives follows:

- Time

Alternative 2 has an advantage over the other two alternativesfor time to implement since it is currently being practicedon a reduced scale. Implementing this alternative would requirecontracts for more trucks to transport the additional flow andto install additional storage capacity. It is estimated thatthis alternative could be implemented in 2 to 4 months.

As with Alternative 2, implementation of Alternative 3 wouldrequire installation of additional storage capacity and•obtaining-additional hauling trucks.-:-,ln-addition*, it may benecessary to amend the current hauling contract to specify anew destination and negotiations must be conducted with theII-l facility. It is estimated that this alternative couldbe implemented in 2 - 5 months. The current practice ofdisposing of extracted groundwater at a Class I facility wouldbe continued until this alternative could be implemented.

It is estimated that design and construction of Alternative 1would take € to 9 months. The current practice of disposingof extracted groundwater at a Class I facility would be con-tinued until the pretreatment plant is on-line.

- Compatibility

Alternatives 2 and 3 are judged to be equal with respect tocompatibility with the future remedy and to have a slightadvantage over Alternative 1 since they can both be discon-tinued or modified with minimal cost on short notice and donot require a large capital investment.

fiiile not as easily discontinued as Alternatives 2 and 3, thetreatment system for Alternative 1 would be made of pre-fabricatcomponents which may be modified to accomodate changes inwaste characteristics and Clow quantities. Pending the resultsof the full-scale RX/PS, the the treatment plant may be adaptedto operate as a component of the final remedy.Alternative 3 is less flexible than Alternatives 1 or 2 inaccomodating changes in waste characteristics and flow quantitiesince Class II-l facilities can only accept specified types andquantities of wastes.

- KeHabilitv/Risk of FailureOnsitet Due to the complexity of operations of a treatmentplant. Alternative 1 may have a greater risk of failure thanAlternatives 2 and 3 which only require extraction and loadingactivities at the site. oooo :• 3

TA*L« 1•UNNAM or COSTS AND KPPtCTIVENMS (VALUATION

•TRINOrCLLOM, CA

Coat

Alt«in*t C«pU»lPreeentnorth

Public HealthConeIderatlone

EnvironmentalConalderatlone

TechnicalConelderetlone

Publlo

followed byplecharge to

•».!•»•• - Mill'effectivelyprevent Migrationof additionalcontamination there-by reducing thefuture threat topublic health Inthe nearby community)Nlnlmal or no threat .to public health Incommunlttee evrvedby the receivingrOTM.

I. Ulapoaal atClaaa Ifacility

114.6*0 . Mill effectivelyprevent algratlonof additionalcontamlnetIonthereby reducing the -future threat topublic health In thenearby communityiNay preeent publichealth hasard toother communitiesIn the event of•lahandllng duringtraneport or dlepoeal.

Mill effectivelyremove contaminatedgroundwater from theelte.Low potential foradverae lapactedue toi traneport oftreated effluentiaecondary treatment•t the receivingPOTMi and dilutionwith aerlne dlecharge.

Mill effectivelyremove contaminatedgroundwater fromthe elte.potential foradveree Impactarelated to highwayepllle or accidentalPotenlal for advereeImpacte related toImproper or Inade-quate dlepoeal atreceiving facility.

Proven technologyutlllaed onelteand at receivingPOTM.Relatively complea .operations reojwlredoneIt* aad atreceiving POTW.Mlek of PaIlure (oron*Ito operation*greater than (orAlternatlvee I • J|Mlek of rallwratraneport leee thaaAlternative* > ft 1|Greater reliability atreceiving facility.•!• to nine month*to Implement.Proceee component* ea*llymodified to accomodat*change* In vaat* cnaractar-letlce and flow ojwantltla*.

OOoo

• Proven technology.• Low compleaIty of opar-

atlone on*It* and atreceiving facility.

• Itlek of (altmrm low (oronelte operation*potentially high dorIngtraneport and atreceiving facility.All but two Claaa Ifacllltlee In CallCoralahave confirm** algnldcant(clave || ftCM violations.

• Two to Covr month* toImplement.

• Eaelly discontinued.

• LI

TAaLt 1 continued8UHMAM OF COSTS AND irrCCTIVCMCSS EVALUATION

•TRlNOrtLLOM. CA

tlternatlve

Cost ff1,0001*Preeent

Capital Wort toPublic HealthConalderatlona

EnvironmentalCon*Ideration*

TechnicalConelderetlona

Woll*

Dlepoaal atCleee H-1Land Dlapoaalfacility

f §,110 - Mill effectivelypravant!mlgratlonof additionalcontaminationthereby reducing the -(utura threat topublic health In fclMnearby community!Nay prenent publichealth haiard toother coamunitle*In the event of•lahandllng duringtranaport or dlepoaal.

Mill effectivelyreeM>ve contaminatedgroundwatar fromthe elte.potential foredvera* Impact*related to highway•pill* or accident*irotentlal for advoraoImpact* related toImproper or Inade-quate diapoaal atreceiving facility.

Proven technology.Relatively lowcomplexity on•It* and atreceiving facility.HI ok of tallura levfor one It* operati

hl«H

accoptablaaltomatlv*.

potentiallytranaport and atrecelvlno facility*Two to flv* awotha tolopleajant.Caally dlacontinw*4.Leea flealbl* than Altor-native* I and I In aecoawdating changea In waatocharacteriatloa MMJ flowquantltlaa.

ooo

• Coat* baaed on fO gpn contlnuoua Clow, ] yaara, 10% annual Intereet, no facility aalvage valve, Monthlypaynenta. Note that the coata preaented do not Include the coet of the following element* vMch aroto each alternative and were described on page ISi additional •torage capacity* gunit* channel aitonalonapiping and additional InterceptIon and monitoring vail*. The total •*Unated coat of thoao Itojui !• ||.«]}»

• Coat do** not Include diapoaal of aludgei thle coat I* considered inalgnlfleant in relation Ucoet of tna alternative. The preliminary coat eatlmat* for aludge dUpoaal la f!9,00«/y*ar.

During Transport; Since untreated waste must be transportedfor about 210 miles for Alternative 2 and about 170 mii»s fOrAlternative 3, these alternatives have relatively greaterrisks of failure than Alternative 3 during transportation dueto the greater potential for traffic accidents.

The risk of failure for Alternative 1 is low since pretreatedeffluent is only transported for a distance of about 15 milesand conveyance of the pretreated waste once it reaches thesewer system is considered to be of extremely low risk.

Receiving Facility; Alternative 1 is most likely to consistentl'provide the level of operation and maintenance required toassure effective, safe handling of wastewater. In the past,some Class I and II-l Land Disposal facilities have violatedRCRA groundwater monitoring and surface impoundment containmentand maintenance requirements. To date, all but 2 Class Ifacilities have substantial (class 1) RCRA violations. Thus,Alternatives 2 and 3 are considered to be less reliable thanAlternative 1.

- Level of Site Cleanup

All three alternatives would effectively attain site cleanupsince they entail removal of contaminated groundwater fromthe site and effectively prevent migration of additionalcontamination downgradient.

Alternative 1 may result in a greater level of overall clean-up since the waste is treated in two stages. First, the on-site facility will remove a large amount of contaminants tomeet discharge requirements of the receiving POTW. Second,the water will be treated again at the POTW prior to oceandischarge.

- Community Impact

Since all three alternatives entail removal of contaminatedgroundwater from the site and effectively prevent migrationof additional contamination downgradient, all three alterna-tives would have positive impacts on the community of GlenAvon and other neighboring communities.Alternatives 2 and 3 may adversely affect other communitiesin the event that improper or inadequate disposal and/or

. transport results in contamination of groundwater or surfacewater.

Alternative 1 is not expected adversely affect the communityin vhich the POTW receiving pretreated effluent ii locatedsince this effluent will be similar to or less hazardous thaneffluent from other industrial sources and only represents asmall percent of the POTW*a capacity.

Alternative 1 is generally supported by the community, Alterna-tive 2 is less acceptable and Alternative 3 is the leastacceptable.

- Technology StatusAll three alternatives utilize proven, commonly practicedtechnologies that when properly maintained and operated areeffective.

- Potential Environmental Impacts

Onsitet All three alternatives will have positive environmentalimpacts at the site since all three entail extraction ofcontaminated groundwater and thereby prevent migration ofadditional contaminants.During Transportation; Concern for spills or exposure during

....transport of waste to the point of disposal is great. Inthe event of an accident during transportation, Alternatives2 and 3 have relatively greater potentials for adverse environ-mental impacts since untreated water will be transported.A spill could result in contamination of soil, surface waterand/or groundwater.

Ultimate Disposal; Under Alternative 1 treated effluent wouldultimately be discharged to the ocean. In .the event of afailure of the onsite treatment facility or the POTW, orboth, this alternative can be expected to have minimal adverseenvironmental impacts due to the large dilution factor ofmarine discharge. In addition, water will be treated twiceprior to marine discharge under Alternative 1.

Alternatives 2 and 3 are more likely to cause adverseenvironmental impacts in the event of inadequate or inappro-priate disposal of Stringfellow groundwater at the receivingfacilities since contaminated water may percolate to ground-water.

Alternative 1 would generate sludge during the pretreatmentprocess. This sludge will be disposed of in a Class 1 landfill.Alternative 1 would use activated carbon that becomes contaminateduring the treatment process. This •spent" carbon will b«regenerated by high temperature incineration for reuse.

- Complexity ef Operation•

Onsttet Alternatives 2 and 3 have the least complex* operationrequirements for onsite activities since only pumping endstorage is required. Alternative 1 requires more sophisticatedoperation activities.Heeeivinq facility; The receiving facilities for all threealternatives have O * H procedures in place since they ere

000027

operating facilities, thus this factor is considered relat ivelyinsignificant. .

- Coat '

Cost estimates were calculated for each of the alternativesbased on the following assumptions:

a v

- 60 gpm average continuous flow (31,536,000 gallons/year)- 3 year operations- 10% interest rate- no facility salvage value

Alternative It Treatment plant capital and operations costestimates for were prepared by CB2N Hill in the Fast TrackRI/FS. Transportation and disposal cost estimates were madeon the basis of information received from SANPA and CBMWDsince completion of the Fast Track RI/FS. Note that thecost_of sludge disposal at a Class I Land Disposal facility

"" is"considered to be insignificant relative to the overall ~*~cost of this alternative and was not included in the followingcost estimates.

Capital Cost (50.015/gal): $1,240,000Operation Cost (50.055/gal): 1,724,000/yearTransportation ($0.023/gal) tDisposal to POTW ($0.020/gal): 1,356,000/year

• •

Present worth Total 3 Year Cost; $9,189,000

Alternative 2; Cost estimates are based on the current costof extraction and disposal.

Extraction ft Disposal Cost (50.18/gal): $5,676 ,000/year

Present Worth Total 3 Year Cost; 514,660,000

Alternative 3t Extraction and disposal estimates were basedon preliminary pricing cost data received from EPC.

Extraction ft Disposal Cost ($0.12/gal): $3,780,000

Present Mbrth Total 3 Year Cost; . $9,770,000Based on the foregoing calculations. Alternative 1 is theleast cost alternative and is less expensive than bothAlternatives 2 and 3.

COMMUNITY KELATIOttS

A community relations plan (CJtP) was developed by DOBS in June,1983. The State is planning to apply for a cooperative agreementamendment to implement the alternative approved in this Recordof Decision. A revised CRP may be included in the amendmentapplication. A moe* comprehensive update will be completed in

oooo:s

the fall of 1984.

A Stringtellow Advisory Committee (SAC) was established by DOHSin September, 1983. The SAC consists of representatives cromcommunity groups, elected officials. County and State agenciesand EPA. The first J5AC meeting was held on September 23, 1983.SAC meetings are held on a monthly, basis.

Funding for a Community Technical Advisor (CTA) was provided inthe cooperative agreement. The CTA will provide the communitywith technical review services throughout the RI/FS. SAC memberswere actively involved in the selection process; they interviewedthe top three candidates in February, 1984 and made a recommenda-tion to DOHS. The consulting firm. Environ, was selected tobe the CTA. SAC members were also involved in the selectionof the RI/FS contractor. They interviewed six of the firmssubmitting proposals and provided comments to the state.

The following documents have been delivered directly to SACmembers for review and comment:

- RI/FS proposals- RI/FS contract- CTA Scope of work- CTA contract- Fast Track RI/FS Work Plan- Final Draft Fast Track RI/FS Report,- Final Fast Track RI/FS Report- Electro-magnetic Conductivity Survey- Final Draft FIT Monitoring Well Completion Report- Final FIT Monitoring Well Completion Report- Final Draft FIT Site Summary Report- SAWPA proposal- selected RI/FS workplans- fact sheets

The period for public comment for these documents ranged fromone to three weeks. The aforementioned documents were alsomade available to other public agencies. Many of these documentswere made available to the public at large and to potentiallyresponsible parties in the Stringfellow case.

The final draft Past Track report was made available for Inter-governmental Review from April 12, 1984 to May 22, 1984. Thefinal Fast Track- report was available for public review fromMay 21. 1984 to June 8, 1984. A notification for public commentwas advertised in southern California newspapers between May4, and: May 18, 1984.Briefings on the Past Track study were held by EPA during theperiod February 15, 1984 to April 17, 1984 for the followingagenciesi Orange County Sanitation District, Santa Ana RegionalWater Quality Control Board, Santa Ana Watershed Project AuthorityOrange County Health Department, Orange County Water Department,U.S. Army Corps of'Engineers, Chino Basin Municipal Water District

Orange County Board of Supervisors, and Los Angeles County San-itation-District. Potentially responsible parties were briefedon February-10, 1984.

A public meeting was held by OOHS in Glen Avon on May 21, 1934.Although CPA was prepared to discuss the Fast Track study, the*discussion focused on the radiation data recently released.Although no formal comments were made at the public meeting,the community is generally supportive of the alternative recom-mended in the Fast Track report.

Written comments on the Fast Track report were received fromseveral agencies and some potentially responsible parties.These comments are addressed in the attached ResponsivenessSummary.

CONSISTENCY WITH OTHER ENVIRONMENTAL LAWS

Two environmental laws that aay apply to the proposed interimmeasure have been identified. They are the Clean Water Act andthe Clean Air Act (5 118(a) and 17(c); 40 CFR 6.303(bM. RCRArequirements are not applicable at this time, thus a 'RCRAalternative' was not developed.

Alternative 1 complies with the Federal pretreatment requirementsof the Clean Water Act and local pretreatment.standards developedunder the authority of the Act. The proposed pretreatment stand-ards are presented in Table 2. The recommended alternative meetsthese requirements. In addition, the receiving POTW will be incompliance with 40 CFR $270.60 (c).

Alternative 1 was reviewed to determine if requirements of theClean Air Act apply. If a proposed CPA action may adversely affectair quality, the responsible CPA official is required to consultwith appropriate State and local agencies on whether the actionconforms with tha State Implementation Plan (SIP).

In response to the State Clearinghouse's request to comment onthe Stringfellow Fast Track RI/FS, the California Air ResourcesBoard wrote a memo* dated May 10, 1984, stating: "We believethat the recommended remedial actions such as groundwater neutral-ixtion, lime treatment, filtration, and carbon adsorption willhave no adverse effect on air quality". Thus, we have concludedthat Clean Air Acfc, requirements are not applicable to the rec<mended alternative} however, air monitoring may be recommendedas a precautionary measure.Although a "RCRA alternative" was not developed* on-site tanksrequired by Alternative 1 will be designed to comply with RCRAPart 264 Subpart J.

000040

RECOMMENDED ALTERNATIVE

Section 300.6B(j) of the National Oil and Hazardous SubstancesContingency Plan (NCF) states that the appropriate extent ofremedy shall be determined by the lead agency's selection Of theremedial alternative which the agency determines is cost-effective(i.e., the lowest cost alternative^that is technologically feasibleand reliable, and which effectively mitigates and minimizes damageto and provides adequate protection of public health, -welfare, andthe environment). Based on evaluation of the cost-effectiveness ofeach of the proposed alternatives, the comments received fromthe public and the State, Region IX recommends Alternative 1,Pretreatment Followed by Discharge to a POTH.

Alternative 1 is the least cost alternative. The estimated 3year present worth of each alternative is listed below:

Alternative 1 $ 9,189,000Alternative 2 $14,660,000Alternative 3 $ 9,770,000

Alternative 1 is also considered to be the most effective alter-native with respect to public health, environmental and technicalconsiderations. The main points made in the effectivenessevaluation presented previously are summarized below:

- Although all three alternatives provide adequate protection ofpublic health to the communities neighboring the site. Alterna-tive 1 is considered to be more effective overall. In the eventof mishandling during transport or disposal. Alternatives 2 and3 may create a threat to public health to other communities.Alternative 1 is unlikely to present this problem.

- All three alternatives effectively achieve site cleanup byremoving contaminated groundwater from the esite. Under Alterna-tive 1, waste will be treated prior to transport and will receivesecondary treatment at the receiving POTH prior to marinedischarge. Thus, Alternative 1 is considered to have the leastpotential for adverse environmental impacts.

- Although Alternative 1 has the most sophisticated operationalrequirements* it is considered to be-most reliable overall. Inthe past* Class I and ZZ-1 Land Disposal facilities have violatedRCRA groundwatar monitoring and surface impoundment containmentand maintenance-requirements. Thus* Alternatives 2 and 3 areconsidered to be less reliable than Alternative 1.

- Alternatives 1 and 2 are expected to be more compatible with futuremedial actions than Alternative 3 since Class II-l facilitiescan only accept specific types and quantities of waste. Therefoia change in waste characteristics could require the use of adifferent Class II-l facility resulting in a disruption of siteoperations and potential increase in disposal costs.

000041

• The coat of Alternative I is somewhat less expensive than thenext costly alternative, Alternative 3. However, Alternative 3is aor« sensitive to future cost growth if the volume ofcontaainated groundwater increases due to changed site condition'or seasonal variations. Disposal costs for Alternative 3 (andAlternative 2) are directly proportional to volume of groundwatedisposed. However, the pretreatment system in Alternative 1will have reserve capacity built in to accoaodate some increasein flows. Therefore, the only Alternative 3 costs associatedwith increased flow would be higher operational costs that wouldincrease at a lower rate than off-site disposal costs.

- The local coaaunity supports Alternative 1.

Two POTVs were identified as potential recipients of Stringfellowwater for Alternative 1. Discussions were held with both of theseagencies to explore the possibility of this arrangement. TheStringfellow site is located within SANPA's jurisdiction. SAWPAhas submitted a proposal to DORS for the purpose of implementingthe alternative recommended in the Past Track report. DORS issupportive of Alternative 1 and has entered into a contract withSAWPA in anticipation of EPA's approval of Alternative 1. DOBS isaware that CPA aay not pay for any expenses incurred prior toselection of a reaedy through the Record of Decision process.

Capital, operating and disposal cost estimates for the recom-aended pretreatment system are presented previously. A processflow diagram of the recommended pretreatment system is presentedin Figure 3.

Alternative 1 includes offsite disposal of sludge which isconsistent with CERCLA 5101(24) in that it is part of the mostcost-effective remedial action and is necessary to protectpublic health, welfare and the environment.

OPERATIONS

Annual operation costs in 1984 dollars are presented below.

Item Annual Cost

Chemicals $ 75,000

Lime - f30,T)0Q/yrCaustic - 140,000/yr

Polymer - 15,000/yearGranulated Activated Carbon ($0.045/gal) 1.419,000Power ($0.09/kMi) 30,000Operating Labor 150,000Monitoring . SO.OOQTOTAL ~ $1,724,000

000012

-25-

Effluent monitoring costs were dtveloped for tiie followingparameters and aaapling frequency: (1) Total OrganicCarbon (TOO on a daily basis* (2) metals on a weekly basis;and (3) priority pollutants on a monthly basis.

Given the interim nature of this-activity, the costs ofoperating the treatment plant will be considered an interimoffsite remedial measure. EPA will consider funding theoperation of the plant on an annual basis, pending availabilityof funds, until a final remedy is implemented. If the treatmentplant is incorporated into the final remedy, EPA's policy topay for one year of O t M costs will go into effect at that time.

The State of California will pay a 10% cost-share of constructionand operational costs. The State's cost-share will be obtainedfrom the State Hazardous Substance Account or from the $4.2million reimbursement funds paid to the State in the StringfellowCooperative Agreement.

SCHEDULE

EPA anticipates the following schedule:

- Approve Remedial Action: July, 1984- Amend Cooperative Agreement for Remedial Design, ConstructionManagement, Site Preparation and Operations: 4th Quarter FY'84

- Begin Design and Site Preparation: 4th Quarter FY'84- Complete Design and Site Preparation: 1st Quarter FY'85- Amend Cooperative Agreement for Remedial Action: 1st Quarter FY*- Begin Construction: 1st Quarter FY'85- Plant on line: 2nd Quarter FY'85- Operations: 2nd Quarter FY'85 - 2nd Quarter FY'38

FUTURE ACTIONS

- Long Tern RI/FS

A full-scale RI/FS was funded under the cooperative agreementwith DOHS. JRB Associates (JRB) is conducting the RI/FS forthe State. The study commenced in March, 1984, and will beconcluded in October* 1985. JRB will conduct studies toidentify and evaluate methods to prevent or manage upgradientgroundwater and surface water entering the site, to preventmigration of hazardous substances offsite, to define aquifercharacteristics, the extent of the contaminant plume, and•ethods of controlling migration. JRB will develop a cost-effective remedial action for final site closure.

- Interagencv Agreement (ZAG)Through an IAG, the US Army Corps of Engineers will provideEPA with technical assistance during remedial design of theinterim measure approved in the Record of Decision and duringthe full-scale RI/FS.

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Remedial ActionUpon completion of the RI/FS, remedial design andaction will be implemented for final site closure.anticipated that the state of California will applyamendment to the cooperative agreement to implement «.site closure. The state will be expected to provide 1 ?n»cost-share for remedial action activities I? il .!»? -0%that a ROD for this purpose wiU *

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RESPONSIVENESS SUMMARY

STRINGFELLOW SITERiverside, California

I. INTRODUCTION

This responsiveness summary addresses the comments madeby governmental agencies and the public concerning the FastTrack Remedial Investigation/Feasibility Study (Fast Track)report for the Stringfellow Site, Riverside, California,issued May 18, 1984.

REVIEW PROCESS

The final draft and the final report were available forpublic review and comment to three Riverside County publiclibraries. The final report was also distributed to publiclibraries in Los Angeles and Orange County; availability ofthe report was noticed in the Los Angeles Times, the RiversidePress Enterprise, and the Santa Ana Register.

Copies of both reports were nailed directly to localagencies, the Stringfellow Advisory Committee (SAC), and counselto selected potentially responsible parties. Written commentson the final draft were received from the Orange CountyWater District, the California Department of Health Services(DOHS), the California Air Resources Board, and the CaliforniaDepartment of Transportation. Comments on the final draftwere incorporated into the final report.

Written comments on the final report were received fromthe California Department of Health Services, the Santa AnaRegional Water Quality Control Board, the Santa Ana WatershedProject Authority (SAWPA), the U.S. Army Corps of Engineers,and counsel to the potentially responsible parties. Commentson the final report and EFA's responses are summarized below.

A list of all cosnents is attached. Copies of commentsreceived on the final draft and the final report are availableat CPA-Region 9 and-CPA-Headquarters.

OBJECTIVES OF THE FAST TRACK

Several comaentors seem to confuse the objectives andscope of the Fast Track study with those of the full-scaleRemedial Investigation/Feasibility Study (RI/FS) which isbeing conducted by DOBS, and which will address the entirespectrum of problems associated with the Stringfellow site.

The Fast Track is a focused effort designed to addressspecific aspects of the overall problem within a shorter time

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than the full-scale RI/FS. The recommendations developed inthe Fast Track study are to be implemented for the interimperiod prior to completion of the full-scale RI/FS and con-struction of the final remedy.

V

As stated in the report* the primary objectives of _theFast Track study are to:

• Develop data on downgradient migration of contaminationto assess public health endangerment.

• Develop criteria for mid-canyon interception of contaminatedgroundwater as a means of mitigating identified publichealth endangerment.

• Identify and evaluate alternative, methods for management. and disposal of contaminated^water collected from onsite

and down-gradient wells.

• Develop a plan for implementation of the most cost-effectivealternative for management and disposal of contaminatedwater collected from onsite and downgradient wells.

Other aspects of assessing hazards and determining costeffective remedial actions are included within the scope ofthe full-scale RI/FS.

II. COMMENTS AND RESPONSES

GROUNDWATER FLOW IN THE BEDROCK

The comstentors contend that bedrock could be a pathwayfor flow of groundwater and transport of contaminants. TheAgency agrees that contaminants could be moving throughfractures and weathered tones in the bedrock. However* theexisting database is insufficient to examine this possibility.Definition of the bedrock hydrogeology represents a sizeableand time consuming data-collection effort. Consequently*this could not have been included within the scope of theFast Track study. As was stated in the Fast Track report*these data will be collected during the RI/FS.

CROONDHATgy

The coeasentors have various concerns regarding the ground-water quality database used in conducting the Fast Trackstudy. In general, these concerns result frost a failure torecognize the purposes of the database and the distinctionsbetween the Past Track study and the RI/FS. The groundwaterdatabase has been valuable in (a) increasing the Agency'sunderstanding of the a real extent of contamination, (b)assessing the endangerment to the public, (c) designing theRI/FS, and (d) designing interim remedial facilities.Considerably more data must be collected during the RI/FS to

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dafine tha araal and vertical axtant of contamination andappropriate long-tarn remedies.

The commentor« atate that there has been an incompleteand inadequate analysis and evaluation of all the data. TheFast Track report did not provide an exhaustive review ofall data collected (i.e., greater than 30,000 data points),because It was designed to be limited in scope and to resultin the selection of interim remedies. The conclusions reachedby tha Fast Track report are supported by the groundwaterquality database. Substantially more data gathering andanalysis will be conducted in tha full-scale RI/FS for selectionof the cost-affective final remedies.

The comaentors state that no analysis of pre-1983 datawas performed. These data are limited in comparison to theextensive data that have been collected in 1983, particularlyfor organics and metals. The pre-1983 data, though notexhaustively reviewed in the Fast Track report, support theconclusions of the report.

The commentors state that the groundwater data collecteddid not provide all the necessary data for designing the recom-mended pretreatment facilities. Samples collected during 1983were analyzed for a broad spectrum of constituents (approximately140 parameters per sampling) with major emphasis on potentialadverse health effects. Many of these same data are usefulin designing pretreatment facilities recommended by the FastTrack report. Additional data, such as TOC, COD, BOD, andTSS, are necessary for pretreatment design purposes, and arecurrently being collected as part of the treatability studythat is recommended by the Fast Track report.

The commentors state that tha analytical scatter andinconsistencies in tha data negated its usefulness. Samplingfrom April through November 1983 resulted in over 30,000 piecesof data. Considerable efforts were expended by the Agency toobtain these data using standardized sampling and analyticalprocedures. The overall sampling results demonstrate consistentpatterns and strongly support tha recommendations of theFast Track raport.HIP-CAM YON HYDROCTOtOCY

Th'e commentors state that considerable uncertainty stillexists regarding the nydrogeology of the alluvial aquifer inPyrite Canyon. Uncertainty does exist and will be addressedin tha RI/FSj however, tha following is certains

• A large volume of contaminated groundwatar exists upgradientof mid-canyonf and

• The direction of groundwatar movement is down-canyon,toward Clan *von. QOCOIiU

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Therefore, interception at raid-canyon of contaminated ground-water will reduce the threat to groundwater supplies dovngradientof Stringfellow.

The commentors criticize the estimate of groundwatervelocity as based on only a few permeability measurements ina heterogeneous aquifer. The Agency agrees that it would bebetter to have more permeability estimates. However, tn*epotential threat to downgradient groundwater supplies dictatesthat a decision be based on existing data. It is reasonableto estimate the average groundwater velocity based on theaverage of the measured permeabilities.

The commentors express concern regarding the scatter inthe permeability data. A wide range in permeabilities istypical of heterogeneous alluvial deposits. Clay strata orcemented alluvium would have a low permeability while sandor gravel strata would have a high permeability. If highpermeability sand and gravel deposits are interconnected,the velocity of some contaminated water would be faster thanthe average velocity estimated in the Fast Track report.

The commentors express concern regarding the assumptionthat trichlorethene (TCE) and chloroform would move at thesame rate as groundwater. The mobility of organic contaminantsmay be affected by physical, chemical or biological processes.However, no data exist to assess the effects, if any, of theseprocesses in Pyrite Canyon. Experience at other sites through-out the U.S. has conclusively demonstrated the mobility of TCEin groundwater. When assessing the potential threat to publichealth, it is necessary to make conservative assumptions;consequently it is reasonable to assume that constituents suchas TCE and chloroform move at the same rate as groundwater.

The commentors criticize the aquifer testing program inthe Past Track study, stating that only step drawdown testswere used. This is incorrect. The Past Track study, includeda 24-hour, constant-discharge aquifer test as well as fourstep-drawdown tests. The 24-hour test was the longest aquifertest performed in the aid-canyon. The Past Track report recom-mends that further testing be performed in the aid-canyon torefine determinations of the long-term response to pumping.Such testing has recently been performed in the aid-canyonusing KW-19, IW-2, and Ztt-3.

The coaaentors state that it has not been demonstratedthat the interceptor wells will fully capture the contaainantsmoving through the aid-canyon. The Agency believes thatadditional hydrogeologic testing will be required to demonstratethat the aid-canyon groundwater interception system fullycaptures contaainants moving through aid-canyon. However,it is certain that pumping existing interceptor wells willremove contaminated groundwater that would otherwise move

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downgradient toward Glen Avon. Removal of these contaminantswill significantly reduce the threat posed to groundwatersupplies. In view of this threat, installation of an operationalinterception system should not await the resolution of -alluncertainties regarding groundwater movement in the canyon.

V

ALTERNATIVE METHODS OF CONTROLLING CONTAMINANT MIGRATION

The commentors state that there nay be better ways ofcontrolling the groundwater than by aid-canyon extraction.The Agency agrees that aeans other than mid-canyon extractionhave merit for controlling migration of groundwater contaminants.Three pump barrel wells (UW-1, UW-2, and UW-3) and a springboxhave been installed upgradient of the site to interceptadditional uncontaminated groundwater and to prevent it fromconveying contaminants from the site. The anticipated effectof pumping these wells will be a reduction in the currentpumping requirements from the onsite wells. The RI/FScontractor is presently developing an operation plan for thepump barrel wells. Upgradient interception of uncontaminatedwater is also a primary objective of the RI/FS.

The commentors urge that as much contaminated water aspossible be extracted from the site in order to remove waterwith the highest levels of contamination. EpA agrees withthis approach. The Fast Trade report recommends continuingthe present onsite pumping program at wells OW-i, OW-2,OW-4, IW-1 and the French Drain. In addition* pumping atmid-canyon is recommended in order to capture contaminantswhich have already migrated beyond the influence of onsitewells.

The commentors argue that surface water diversion wasnot considered as an alternative remedial measure. Infiltrationof surface water is a potential source of recharge of bothcontaminated and uncontaminated water throughout PyriteCanyon. Diversion of surface runoff may be a component ofthe final remedy to be employed at the site. To determinethe need for and to design additional surface water diversionstructures extending down-canyon requires knowledge of theprecipitation characteristics of the site itself and a betterdefinition of the site water budget. These data do notexist and their <e41ection would require an extensive bydrologicmonitoring program which will b« performed during the RI/FS.

CAPTURE OF DOWNGRADIEKT CONTAMINANTS

The commentors point out that the Aid-canyon interceptorwell system will not reverse contaminant flow or remove con-taminants that have already migrated past this aid-canyon area.The Fast Track report definitively acknowledges this problem.However, as indicated above, the objectives of the PastTrack study are 1 United. The RI/FS will investigate theextent of contaminant migration past the mid-canyon area and

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the need for remedies. Because the bulk of the known contam-ination -is sttll upgradient of the mid-canyon, interceptionof groundwater froa the aid-canyon will prevent the furtherdeterioration of groundwater quality past this area.

PRETREATHENT STANDARDS

The coamentors have questioned the need to pretreat"extracted groundwater prior to discharge to a regional inter-ceptor. As described in the Past Track report, each of thethree candidate Publicly Owned Treatment Works (POTW) systeasfor disposal of Stringfellow water has established qualitylimitation* for discharges into its systea. Untreated String-fellow groundwater exceeds the quality limitations of allthree of the systeas and could not be discharged to any onewithout pretreataent. Discussions between CPA and Santa AnaWatershed Project Authority (SAWPA), County Sanitation Districtsof Orange County (CSDOC), Chino Basin Municipal Water District(CBMWD), and Los Angeles County Sanitation Districts (LACSD)have confirmed this determination.

The coaaentors have challenged the appropriateness ofthe proposed pretreataent standards and suggested that accept-able water quality requirements for discharge of extractedgroundwater to regional interceptors be obtained or negotiated.As described in the Past Track report, the operator of aregional interceptor (SAWPA or CBMWD, in this case) Bustobtain concurrence from the receptor POTW (CSDOC or LACSD)for all industrial wastes adaitted into its system. ThePOTW aay deny a permit for discharge that it believes couldadversely affect the operation of its treatment plant, orwhich could affect compliance with its NPDES permit require-ments. The burden of establishing that no adverse effectswill result falls upon the waste generator. It was withthese considerations in mind, and after discussing the matterwith representatives of SAWPA, CSDOC, CBMWD, and LACSD, thatCPA adopted the approach presented in the Past Track reportfor developing the proposed pretreataent standards.

The coaaentors also suggest the EPA did not contact SAWPAto discuss the requirements for discharge of Stringfellowwater into the SARI line. This is not correct. Froa thestart of the Past-T*ack study in September 1983, EPA hasworked with SAWPA to define a mutually satisfactory basisfor discharging Stringfellow water into the SAWPA systea.EVALUATION OP ALTERNATIVES

The coaaentors stats that the Past Track study shouldhave relied more heavily upon a matrix analysis for thecomparison of alternatives* The Past Track study employedmethods of analysis which are consistent with the intent ofthe NCP and CPA guidance. Several alternatives discussed and

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not recommended by the Fast Track report, as well as combinationsof portions of. these alternatives* remain under considerationin the full-scale RZ/FS. Given the objectives and limitedscope of the Fast Track study, these alternatives were notappropriate for further consideration as interim measures.

The comaentors state that solar evaporation and airstripping should have been more thoroughly evaluated in theFast Track study. The primary reason for eliminating solarevaporation during the initial screening process was that noavailable, suitable land area was identified. Establishmentof surface impoundments for solar evaporation either in PyriteCanyon or else where in the vicinity was judged to be unaccept-able to the surrounding community. It should be noted thatthe existence of the Stringfellow site as an uncontrolledhazardous waste site is due to a failed attempt at solarevaporation. A second attempt at onsite solar evaporationwas anticipated to be contested by the comunity and localagencies and could preclude implementation of this alternativein the three to five year interim period of the full-scaleRJ/FS and the construction of the final remedy.

Air stripping was rejected as a suitable pretreatmentoperation primarily because it is capable of removing onlyvolatile organic compounds (VOC). It is not effective forremoving acid or base-neutral extractable compounds, whichare also present in the Stringfellow groundwater. It wasalso rejected because of its potential for VOC emissions.The length of time needed to study the potential VOC emissionwas beyond the scope of the Fast Track study and will beincluded in the RI/FS.

ADDITIONAL STUDIES

The commentors assert that the Fast Track study isdeficient due to the lack of treatability work and long-termpump testing of the aquifer in the mid-canyon region. Bothof these studies were recommended in the Fast Track report asthe next required activities and have been conducted.

TRICHLOROETHEKE

A commentor stated that the organic chemical "trichloro-•thene* referred t'o*ln the Fast Track report does not exist.The commentor expresses a familiarity with *trichloroethylene"and apparently is unaware that the terms, 'trichloroethene*and *trichloroethylene* are synonomous. The proper name forthe compound in question, C^HClj, under the 'Geneva system*adopted by the International Congress held at Geneva, Switzer-land, in 1892, is trichloroethene. This system, which coversthe primary phases of the nomenclature of organic chemistry*has been repeatedly reaffirmed and extended since its inception.

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LACK OF'ADHERENCE TO THE WORK PLAN

The commentors state that the primary objectives of. theFast Track study were not accomplished and that discrepanciesbetween the work plan and the work~as presented in the finalreport compromised the quality of the study. Although certainelements of the scope of work were not performed as originallydescribed, the primary objectives of the work plan have beenfully «et. Changes were nade according to the exigencies ofthe work as it progressed. In some cases* items of the workplan became impossible to perform within the scope of theproject. For example, negotiations with SAWPA could not becompleted before completion of the Fast Track study and arecontinuing with EPA and OOHS.PAST REPORTS

The commentors state that the Fast Track study failed torefer to past reports and data. The Fast Track study reviewedand, as appropriate, utilized previously generated reportsand data on the Stringfellow site. Previous studies, suchas those conducted by J.M. Montgomery, Consulting Engineers,Inc., while providing useful insight, were often out-of-dateor did not consider information now available. For example,in a 1981 report, J.H. Montgomery recommended discharge tothe SARI line, but assumed that an extension line would beconstructed to within one mile of the site, allowing a directconnection from an onsite treatment plant to the extensionline. In fact, this extension line has not been built.

OTHER AGENCIES' COMMENTS

Comments received from the Hazardous Materials LaboratorySection of California Department of Health Services weredetailed and largely consisted of editorial suggestions.Many of these have merit, but overall do not alter the con-clusions presented in the Fast Track report.

The Santa Ana Regional Hater Quality Control Board, Cali-fornia Department of Transportation, and California Air ResourcesBoard have each concurred in the recommendations of the FastTrack report* The California Department of Transportationstressed that adequate consideration be given to potentialhazards associated with truck hauling of untreated hazardouswastes.- The California Air Resources Board noted that additionalstudy would be required if air stripping were to be consideredfurther.

Comments received from the 0. S. A ray Corps of Engineersgenerally cover the sa»e topics discussed by other commentors.Responses previously presented in this document address thesecomments.

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III. CONCLUSION

The comments received were helpful, but were not of anature to cause a revision in the findings of the study. '

The Santa Ana Watershed Project Authority (SAHPA) hassubmitted a proposal to DOHS under which SAWPA would implementthe alternative recommended in the Fast Track report. SAWPAis one of the sewerage authorities recommended by the PastTrack report for disposal of the pretreated groundwater. inanticipation of EPA's approval of the remedy recommended bythe Past Track report* DOHS has entered into the first phaseof a contract with SAWPA for contractor procurement. Followingthis first phase of the overall program, DOHS plans to enterinto additional contracts with SAWPA for contract management,design, construction and operation of the pretreatment plant.

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