Explanation of Significant DifferenceTo The Record of Decision

Oklahoma Refining Company Superfiznd siteCyril, OklahomaMarch 27, 1996

I. IntroductionThe Oklahoma Refining Company (ORC) Superfund site ("the site")is a former refinery located in Caddo County, on the eastern edgeof Cyril, Oklahoma, approximately 75 miles southwest of OklahomaCity, Oklahoma. The Oklahoma Department of Environmental Quality(ODEQ) is the lead agency for remediation of the site, under aCooperative Agreement with the U.S. Environmental ProtectionAgency (EPA). The EPA is the support agency for siteremediation. The remedial action work is being funded by thefederal Superfund program. The 60% design was recentlycompleted, following the completion of the 30% design and a ValueEngineering study. All were completed under ODEQ oversight andsupervision.

"iThis Explanation of Significant Differences (ESD) is prepared infulfillment of EPA's public participation responsibilities underSection 117 (c) of the Comprehensive Environmental Response,Compensation and Liability Act (CERCLA), 42 U.S.C. S 9617(c),which provides that after adoption of a final remedial actionplan, if any remedial action is taken, settlement or consentdecree under Section 106 or Section 122 is entered into, and ifsuch action, settlement, or decree differs in any significantrespects from the final plan, the President or the State shallpublish an explanation of significant differences and the reasonssuch changes were made. 42 U.S.C S 9617(c). Moreover, pursuantto the National Contingency Plan (NCP), 40 C.F.R. Part 300, EPAis required to publish an ESD when, after adoption of the Recordof.Decision (ROD) the remedial action or enforcement actiontaken, or the settlement or consent decree entered into, differssignificantly from the remedy selected in the ROD with respect toscope, performance, or cost. 40 C.F.R. S 300.435 (c) (2) ( i ) .The following changes were identified during the preliminarystages of the Remedial Design:Asphaltic MaterialsThe Remedial Investigation/Feasibility Study (RI/FS) for thesite, completed in 1991, identified approximately 2640 cubicyards of asphalt as well as 8200 cubic yards of asphaltic pitchat the site. The remedy selected in the ROD, executed by EPA inJune of 1992, contemplated recycling these asphaltic materials.However, no viable recycling option was identified in theremedial design. Prior to the start of the 30% design, EPA andODEQ considered modifying the remedy from recycling to onsitedisposal of asphaltic materials. Under the new onsite disposaloption, the asphalt will be stabilized and placed on top of the

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'.-pitch pits. The stabilization is only necessary to improve theworkability characteristics of the material. The pitch pits andstabilized asphalt will be capped in place. The capping of thepitch pits was recommended during the Value Engineering study.Placing stabilized asphalt on the pitch pits rather than in the; "landfills, which was recommended by the design engineer following

i; the completion of the 60% design, will expedite the remedy anddecrease costs. This modified remedy will still be protective ofhuman health and the environment.Ground Water RemedyThe RI/FS also identified ground water contamination in the RushSprings Sandstone beneath the site. The ground water remedyselected in the ROD consisted of a line of containment wells toprevent discharge of the contaminated ground water to GladysCreek, an onsite water treatment facility, and re-injection ofall treated water to stimulate bioremediation. The ROD alsocalled for the treatment of any surface water, including stormwater and surface water from the impoundments, exceeding RemedialAction Objectives,, in an on-site water treatment facility.On December 5, 1995, the EPA and the ODEQ agreed to implement thegroundwater portion of the remedy in a second construction phaseafter the completion of the source remedy. Field studiesperformed during the Remedial Design in April 1995 revealed thatthe groundwater problems associated with LNAPLs were much lesssevere than originally determined by the RI/FS. Therefore, it isconsidered prudent management to postpone the groundwater remedyto phase II. EPA and ODEQ believe that risk posed bycontaminated groundwater will be lessened by source treatment andconstruction of a subsurface LNAPL trench. The subsurface LHAPLtrench will be constructed as part of the waste source andsediment remedy. EPA and ODEQ will evaluate the necessity forphase II groundwater treatment after implementation of the sourceremedy.Treated Water DischargeThe ROD calls for the treatment of all onsite water, which couldinclude water generated from activities such as dewateringsurface impoundments and excavations, collection of storm water,well development, and ground water extraction. The ROD directedall treated water to be reinjected into the Rush SpringsSandstone aquifer. Oewatering of surface impoundments andexcavations and collection of storm water will continue under themodified remedy. However, the postponement of the ground waterremedy means there will be no permanent onsite water treatmentfacility during the construction activities to address thesurface contamination. Therefore, a temporary discharge forsurface water will be necessary during remedial action.Generated waters will be treated in a temporary water treatmentunit and discharged as needed. All discharged water will meetthe permissible discharge limits established by the ODEQ in

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accordance with Water Quality Standards established in OklahomaAdministrative Code Title 785.This document presents only a summary of the changes to theremedy and a synopsis of available information on the site.Pursuant to the requirements of the NCP, 40 C . F . R . § 300.825(a) ( 2 ) , this ESD will become part of the Administrative Recordfor the site.II. Site HistoryThe ORC Superfund site is located in Cyril, Oklahoma in CaddoCounty at the eastern edge of Cyril, Oklahoma at the Intersectionof U.S. Highway 277 and State Highway 7. The site is bordered byGladys Creek to the east, U.S. Highway 277 to the north, the Cityof Cyril to the west, and a tributary of Gladys Creek to thesouth.The Anderson and Pritchard Company (APCO) operated a largerefinery at the site from 1920 to 1978. The ORC purchased therefinery in 1978 and operated it unt-^1 1984. ORC filed forbankruptcy protection in the U.S. District Court for the WesternDistrict of Oklahoma in September of 1984, and ceased operationsat that time. In 1986, the bankruptcy court granted thebankrutpcy trustee's motion to abandon the southern portion ofthe property, which is where most of the environmental problemsexist. In 1987, Cyril Petroleum Corporation (CPC) purchased thenorthern portion of the site from the bankruptcy estate.The ORC site was added to the EPA National Priorities List (NPL)in June 1988. This listing made the site eligible for federalfunds to remediate the contamination at the site. In 1988, theOklahoma State Department of Health (OSDH) was awarded fundingthrough a cooperative agreement with the EPA to perform aRemedial Investigation and Feasibility Study (RI/FS) at the ORCsite. OSDH entered into a Consent Agreement and Final Order(CAFO) with CPC on January 28, 1992. By that order, CPC hasagreed to address groundwater contamination, stormwater drainageand above and below-ground storage tanks. In July, 199 3» a newstate agency, the Oklahoma Department of Environmental Quality(ODEQ), assumed environmental responsibilities of the OSDH. TheODEQ accepted the ORC project with no interruption in theSuperfund process.In 1993, CPC refurbished part of the refinery and began renewedrefining operations. Currently, CPC is conducting refiningoperations at a much smaller scale than past operations. Theactive status of the refinery should not impact the plannedcleanup activities.III. ContaminationThe refining processes that were utilized by the APCO and ORCrefineries included crude distillation, vacuum distillation,catalyst cracking, alkylation, bi-netallic reforming, and

004904

^downstream processing. Wastes were placed in pits or iand-<' "applied on the refinery property. Wastewater was sent through an[ oil-water separator to recover oils and then treated in a series' of surface impoundments. Treated water from the surface

, impoundments was discharged into Gladys Creek. Gladys Creek is atributary of Chetonia Creek, approximately one mile downstream.

-: Chetonia Creek empties into the Little Washita River, 1.75 milessouth of the site. Leakage from crude oil tanks, product tanks,and surface impoundments occurred during the many years ofproduction. This resulted in contamination of soil, sediment,surface water, and shallow ground water beneath the site.Some or all of the contaminants identified at the site are"hazardous substances" as that term is defined in Section §101(14) of CERCIA, 42 U.S . C . S 9601(14), and 40 C.F.R. f 302.4.Many have potentially adverse effects on humans or other lifeforms. The contaminants present onsite include benzene, phenol,toluene, xylene, methylphenol, naphthalene, ethylbenzene,polycyclic aromatic hydrocarbons, arsenic, cadmium, chromium,lead, mercury, nickel and zinc, as well as areas of low and highpH.The Remedial Investigation (RI) began in 1989 and was completedfor the ORC site in September 1991. The RI found extensivesurface and subsurface contamination of petroleum related organiccompounds, heavy metals, and acidic and caustic materials. Theuppermost aquifer at the site, the Rush Springs SandstoneAquifer, was found to be contaminated by dissolved organic andinorganic compounds.A risk assessment, conducted as part of the RemedialInvestigation, concluded that exposure to current off siteresidents and onsite intruders was within EPA's acceptable riskrange, but exposure to potential onsite residents and onsiteworkers was not at an acceptable level.The Feasibility Study (FS) for the ORC site began in 1989 and wascompleted in December 1991. The FS identified the soils,sediments, surface water, and ground water that needed to beremediated at the site and the levels of contamination to bereached during renediation. The FS report then developed severalalternatives for remediating the site and evaluated thesealternatives•IV. Selected RemediesBased on the RI/FS, the OSDH and EPA developed a proposed plan toremediate the site and solicited public comments on that plan.The Record of Decision (ROD), a legally binding document thatexplains how EPA intends to remediate the site, was prepared bythe combined efforts of OSDH and EPA, and was based on theproposed plan and comments received by EPA from the publicconcerning the proposed plan.

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In June 1992, the U.S. SPA signed the ROD and OSDH began planningthe Remedial Design for the site. The remedy .selected in the RODconsisted of the following major components:

1. Extraction of light non-aqueous phase liquids(LNAPLs), primarily hydrocarbons, that are commingledwith hazardous waste and recycling the recoveredLNAPLs.

2. Treatment of extracted ground water in a watertreatment facility to be constructed onsite, andinjection of the treated water into contaminatedportions of the aquifer to enhance bioremediation.The treated ground water that is reinjected would meetthe Maximum Contaminant Levels (MCLs) contained i-* theSafe Drinking Water Act.

Removal of all onsite surface water from impoundmentsand treatment of the contaminated water in an onsitewater treatment facility.

In-situ bioremediation of contaminated sediments.

5. Excavation of contaminated sediments and soils thatcannot be treated in-situ, followed by biotreatmentand/or stabilization, if necessary, and containment inan onsite landfill.

6. Excavation and neutralization of low pH (acidic)sediments, followed by placement of treated materialsas fill in the excavated area.

7. Excavation and recycling of asphaltic materials.

8.

9.

Containment and collection of contaminated groundwater at the downgradient site border by using groundwater extraction wells, followed by treatment of thewater in the water treatment facility.Continued injection of treated water into contaminatedportions of the aquifer to enhance bioremediation ofcontaminated groundwater.

The Remedial Design and subsequent Remedial Action was originallyplanned as two phases. All of the work has now been combinedinto one design phase that is planned to be completed in May of1996. At that time, ODEQ will issue an invitation to bid andselect a contractor to implement the Remedial Action.V. Explanation of Significant DifferencesThe significant differences between the revised remedy and theremedy selected in the ROD are: (1) capping in-place of theasphaltic materials rather than recycling; (2) postponement of

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^the ground water portion of the remedy; and (3) a temporary^discharge of treated water to Gladys Creak. These differencesare described in more detail below.

^-^ - -. ' •^ Asphaltic Materials

- A-

-'-'"The modification of the remedy to capping of the pitch pits (8200cubic yards) is based on a recommendation by the ValueEngineering (VE) study performed under ODEQ's supervision as partof the Remedial Design. The pitch material is not mobile and hasa very low migration potential, which has been verified throughground water monitoring in the area. Capping the pitch pitsin-place will prevent exposure via direct contact and will beequally protective as recycling the material. Furthermore, thisoption will simplify the remedy by-eliminating the excavation,handling, and disposal of the pitch in the onsite hazardous wastelandfill. This change will result in savings of approximately$1.28 million in capital costs as estimated by the VE study. Thefact that this modified remedy provides an equal level ofprotection, coupled with the cost savings, justifies itsimplementation. . .

The other asphaltic materials (2640 cubic yards) have relativelylow viscosity, increasing their potential to migrate. Thesematerials are not suited for capping in-place. The small volumeof these materials does not justify the cost to performadditional studies for onsite recycling. The material in AsphaltPits #2 and f3 and Old Storage Pits #1, #2, and #3 will bestabilized and placed on top of the pitch pits prior to capping.

Ground Water

The ground water beneath the site is contaminated above MaximumContaminant Limits (MCLs) for drinking water and also has LNAPLsthat are commingled with hazardous waste. No drinking waterwells have been "Identified within the area of ground watercontamination. The contaminated ground water does discharge toGladys Creek. The risk assessment, conducted as part of the RIin 1990, concluded that the contaminant levels in the creek didnot pose adverse risk to the public. The ROD requires that anotice be attached to the property deed to inform future landowners that the ground water contains contamination and shouldnot be used as a drinking water source.'

During the VE study it was recommended that, due to the lowthreat presented by the groundwater, the groundwater phase ofthis remedy be postponed until after the surface remedy iscompleted and analyses can be performed to determine thenecessity of groundwater treatment. Following implementation ofthe waste source and sediment portion of the remedy, a criticalanalysis of the risks posed by the ground water will be performedby the ODEQ. This will focus primarily on Gladys Creek, as thecontaminated ground water discharges at the site boundary. Afterthe remedial action is completed to eliminate the source of

004907

contamination, EPA and ODEQ will collect data to evaluate theaffect of source removal on ground water contamination. On orbefore the conclusion of the source control portion of theremedy, EPA and ODEQ will determine the appropriateness of futuregroundwater treatment, as set forth in the ROD. Long-term groundwater monitoring and surface water and sediment sampling will beretained as part of the remedy.

Treated Water DischargeThe decision to postpone the ground water portion of the remedymeans an onsite water treatment facility will not be constructedat this time. This will necessitate a temporary discharge lineto Gladys Creek for water generated during that phase of theremedial action. A temporary water treatment unit will be usedto treat water prior to discharge. The discharge of water fromthe site will be temporary and the discharge line will be removedat the completion of that phase of the remedy. All water to bedischarged will be treated to meet I IQ discharge limitsestablished by the'ODEQ. Permissible discharge levels, whichwill be protective of human health and the environment, weredetermined by ODEQ, and are provided in Attachment A.VI. Community InvolvementThe goal of Superfund community relations activities is to ensurethat citizens are kept well informed and have a voice indecisions made about Superfund'actions in their communities.Public involvement contributes to sound decisions and greaterprotection of public health and the environment. Since the RODwas signed, information on significant actions and progress atthe site has been disseminated through open houses and factsheets. An open house meeting will be scheduled both to informthe public of the changes regarding the disposition of theasphalt and the discharge of treated water into Gladys Creek, anddiscuss any community concerns. Additional public informationworkshops and meetings will be held during the course of theproject as needed. Public notice for this ESD will be issued onApril 10, 1996 in The Cvril News and The Lawton Constitution.The Administrative Record for the Oklahoma Refining Company site,is a record of the information that EPA considered in selectingthe remedy for the site, and is available for public review atthe following-locations:Cyril City Hall202 W. MainCyril, Oklahoma(405) 464-2411Hours: M-F 9:00 a.m.-2:00 p.m.

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T'~ Oklahoma Department of Environmental Qualityi 1000 N.E. 10th Street - 8th Floor

Oklahoma City, Oklahoma 73117-1212^Z(405) 271-7157-^Hours: M-F 8:00 a.m.-4:30 p.m.

U.S. EPA Region VI1445 Ross AvenueDallas, Texas 75202-2733(214) 665-8516 or 1-800-533-3508Hours: M-F 8:00 a.m.-4:30 p.m.VI. state AcceptanceThe State of Oklahoma, through the ODEQ, concurs with th-proposed changes to the remedy to cap the pitch onsite, stabilizethe asphaltic materials and cap with the pitch pits, add atemporary discharge for treated surface water to Gladys creek,and postpone the ground water portion of the remedy. The ODEQbelieves these changes maintain the intent of the ROD to protecthuman health and the environment. The letter reflecting ODEQ'sacceptance of the modified remedy is attached hereto.

VIII. Affirmation of Statutory DeterminationsConsidering the new information that has been developed duringthe Remedial Design and the changes to the selected remedydescribed in this document, the EPA believes that the site remedyremains protective of human health and the environment, complieswith federal and state requirements that were identified in theROD as applicable or relevant and appropriate to this remedialaction, and is cost-effective. No fundamental change to theremedy selected in the ROD has been made under this ESD. If theground water remedy is not implemented as set forth in the ROD,'an amendment to the ROD will be required.

Date

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ATTACHMENT A

The final limitations for the Oklahoma Refining Company site willbe based on the more stringent limitations of the technology-basedor water-quality based limits. These limits are listed below:

PARAMETER

ArsenicBenzeneChromiumCopperLeadNickelOil and GreasePhenols'tolueneTotal Organic CarbonXyleaeZinc

Water Quality Based

Daily Avg.mg/l

0.1311 . 5 1 70.0340.0550.0330.664---

0.603--

0.301

Daily Max.tng/1

0.3123.6130.0820.1310.0801.58315.0-

1.437—-

0.717

Technology Based

Daily Avg.rug l

—0.050-———

10.00.150.05050.0

0.100—

Daily Max.mg/1

—0.15

————

15.00.250.30

Report0.15

—

Permit Limits

Daily Avg.rag/I0.1310.0500.0340.0550.0330.66410.00.15

0.05050.0

O.LOO0.301

Daily Max.mg/10.3120.150.0820.1310.0801.58315.00.25030

Report0.15

0.717

8

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MARK S. COLEMANExecutive Director

FSAiN'K SEATINGGovernor

State of OklahomaDEPARTMENT OF ENVIRONMENTAL QUALITY

March 26, 1996

Jane N. Saginaw, Regional AdministratorU.S. EPA, Region 61445 Ross AvenueDallas, TX 75202

Re: Oklahoma Refining Company Superfund Site

Dear Ms. Saginaw:

We accept the proposed changes described in the Explanation of SignificantDifferences to the Record of Decision for the Oklahoma Refining CompanySuperfund site. The changes represent a savings of $16.2 million in capital andoperation and maintenance costs and demonstrate a practical approach to theclean up efforts. We believe the changes will achieve protection of humanhealth and the environment as described in the Record of Decision.

Please fee! free to call me if you wish to discuss this matter further.

Sincerely,

i^iJLltL.^Mark S. ColemanExecutive Director

cc: H. A. Caves, Division Director

. -i;-;•'

S .1'' — ^ ^ -'~".^,'- —, "f r— '"'— i.J y^"^ -^s.•te ^ mp:< ^ .J

CO

<La1000 Northeast Tenth Straat, Oklahoma CEqr, Oklahoma 73117-1212 W recydeA paper

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