06/21/2004 14:20 14052823358 NEXTEP-CIMARRON PAGE 02/03

CIMARRON CORPORATION

P.O. ROX 31 * CSRCA. AOK-73029

May 27,2004

Mr. Kenneth Kalman

Low-Level Waste & Decommissioning Projects Branch

Division of Waste Management

Office of Nuclear Materials Safery & Safeguards

U. S. Nuclear Regulatory Commission

Washington. D.C. 20555

Re: Docker No. 70-925; License No. SNM-928

Notification of EPA in Accordance with Memorandum of Understanding

Dear Mr. Kalman:

Cimarron Corporation (Cimarron) reviewed several letters recently posted on the NRC website

regarding EPA notification of several licensed sites in accordance with the October 2002 NRC-EPA

Memorandum of Understanding (YOU). Cimarron understands that NRC will provide similar

notification for the Cimarron site in the near future, and wants to ensure that NRC is aware of certain

information that should be included in the notification to the EPA.

The Oklahoma Department of Environmental Quality (DEQ) administers both CERCLA and RCRA

programs in the State of Oklahoma. Cinarron has worked with DEQ to establish a groundwater

criterion for the Cimarron site. In August 1997, Cimarron submitted Work Plan for a Risk Assessment

for Groundwater for the Cimarron site to the DEQ for review and approval. DEQ approved the work

plan in a letter dated October 24, 1997. The DEQ-approvcd risk assessment methodology was

consistent wvith guidance developed by the National Research Council (1983) and the U.S.

Environmental Protcction Agency (EPA, 1989). The risk assessment also addressed ecological

concerns. U.S. EPA guidance utilized to perform the Risk Assessment included:

1. Risk Assessment Guidance for Superfund (RAGS), Volume 1: Human Health Evaluation

Manual (Part A) (EPA 540/1-89/002);

2. Risk Assessment Guidance for Superfund (RAGS), Volume 1: Human Health Evaluation

Manual. Supplemental Guidance "Standard Default Exposure Factors", March 25, 1991

(PB9I-9213 14);

3. Soil Screening Guidance: User's Guide. USEPA Office of Solid Waste and Emergency

Response (EPA/540/R-96-018; Publication 9355.4-23);

4. Soil Screening Guidance: Technical Background Document. USEPA Office of Solid Waste

and Emergency Response (EPA/5401R95/128);

5. Dermal Exposure Assessment: Principles and Applications. USEPA Office of Rcsearch and

Development (EPA1600/8-91/01 1B);
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6. Guidance for Data Usability in Risk Assessment. USEPA (EPA/S40G-901008); and

7. Radiation Exposure and Risk Assessment Manual (RERAM). USEPA Office of Air and

Radiation (EPAi402-R-96-016)

Additional EPA guidance documents utilized during the performance of the Risk Assessment are

identified in Section 10 of the June 1998 Risk Assessment for Groundwater, which Cimarron submitted

to both DEQ and NRC. The risk assessment was performed in accordance with the DEQ approved

work plan, and established a risk-based criterion (a '"re-opening" criterion) of 0.11 mg/L (1 10 pg/L) for

uranium. The Risk Assessment focused solely on the potential risks associated with chemical

contaminants (i.e. uranium) in groundwater and did not address radiological risks.

In July 1998, Cimarron submitted Decommissioning Plan for Groundwarer to both DEQ and NRC.

This document demonstrated that I SO pCi/L uranium in groundwater equates to an annual dose of 25

mremlyr, utilizing the most conservative scenario (i.e. drinking water scenario). Page 9-7 of that

document explained that the risk-bascd criteria of 0.1 mg/I equates to approximately 180 pCi/L (182.5

pCiL at 1.2%Sc enrichment).

In August 1998, DEQ reviewed and commented on Risk Assessment for Groundwater. In Comment

r8, DEQ requested clarification that NRC's documents address the radionuclide risks, and that those

risks not be a pan of the chemical toxicity assessment.

On September 21, 1998, Cimarron responded to DEQ comments and submitted a revised Risk

Assessment for Groundwater. Suction 4.2.3 of that document stated, "The potential risks associated

witih uranium as a radionuclide have or are being addressed by the NRC (Cimarron, 1998) and as such

will not be considered as a part of the chemical constituent risk assessment in this document." In a

letter dated January 4, 1999, DEQ accepted the Risk Assessment for Groundwater.

Under CERCLA, EPA routinely uses Maximum Contaminant Levels (MCLs) as screening levcls, and

encourages responsible parties to develop site-specific risk-based limits using established methods. A

site-specific, risk-based criterion for uranium in groundwater was developed in accordance with a

DEQ-approved work plan using EPA guidance, and the resulting limit was approved by DEQ for the

Cimarron site. Consequently, the risk-based limit (0.11 mg/L (110 ggL) uranium) replaced the

federally promulgated MCL as the cleanup goal for the site, potentially negating the need to include the

Cimarron site in the Level I notification to EPA.

If you have questions or comments, please call me at 405-282-5680, ext. 120 (Cimarron) or 918-223-

2522 (Cushing).

Sincerely,

Jeff Lux

Manager, Planning and Regulatory Compliance

xc: D. Blair Spitzberg. NRC Region IV

Derek Widmayer, NRC

David Cates, DEQ