ML20215J967

Forwards Comments on Listed Repts Sent by Doe,In Support of Draft Remedial Action Plan & Draft Environ Assessment for Green River,Ut,Following Review of Documents.Resolution of Relevant Comments Will Be Noted During Review of Final Plan

ML20215J967
Person / Time
Issue date:	05/29/1987
From:	Lohaus P NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
To:	James Anderson ENERGY, DEPT. OF
References
REF-WM-68 NUDOCS 8706250172
Download: ML20215J967 (5)

Text

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_ MKnapp James R. Anderson, Project Manager Jcreeves i

~~ JStarmer Uranium Mill Tailings Project Office U.S. Department of Energy

~ MTokar Albuquerque Operations Office

- Jcrimm P.O. Box 5400 7/ TJohnson Albuquerque, NM 87115 E f SSmykowski MYoung

Dear Mr. Anderson:

RDSmith (URFO)

Enclosed are NRC staff comments on the following reports:

Site Conceptual Design Civil Engineering Calculations (Volumes I and II)';

Site Conceptual Design Geotechnical Engineering Calculations; Site Conceptual Design Radiological Engineering Calculations; Site Conceptual Design Geology, Seismicity, and Geomorphology; Site Conceptual Design Geotechnical Raw Laboratory Data; ReportUMTRA.SNL/744244(1983), containing results of drilling, sampling and aquifer test of monitor wells, and of surface water sampling; and Slug test and pump test data related to potential ground-water impacts in the l

vicinity of the proposed disposal area.

These reports were sent by DOE in support of the draft Remedial Action Plan (dRAP) and draft Environmental Assessment (DEA) for Green River, Utah, following the staff's review of those documents. The enclosed comments are provided for DOE to consider, in addition to the staff comments on the DEA and dRAP, in development of the final RAP and final EA. Resolution of all relevant staff comments will be noted during our review of the final RAP.

Should you have any questions, please contact Susan Bilhorn of my staff at FTS 427-4145.

Sincerely, j

OR'.j'enA I c$'.3Md h Paul H. Lohaus, Acting Chief Operations Branch i

Division of Low-Level Waste Management l

8706250172 070529 and Decommissioning l

PDR WASTE PDR Office of Nuclear Material Safety i

WM-68 and Safeguards Enclosures : As stated 1/

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UMTRA DOCUMEhT REVIEW FORM SECTION 1 Site: Green River, Utah

, Date: May 28, 1987 Document: Informat1on Supporting dRAP and DEA I

Commentor: NRC Staff / Ground Water Hydroloqy j

l Comment:

1 Aquifer Test Data Based on review of the test data used to characterize aquifers associated with the Green River site, the staff have identified several discrepancies. These discrepancies may have significantly affected the results_ presented in the DEA and dRAP.

In order to fully evaluate the adequacy of results presented in the DEA and dRAP, the staff needs clarification on the test procedures, analytical assumptions, and uncertainties associated with collection and a,nalysis of this data. The descrepancies and information needs identified by the staff are highlighted in the following four paragraphs.

(Page 1 of 3) 1 SECTION 2 Response: Page By:

Date:

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Plans for Implementation:

SECTION 3 Confirmation of Implementation:

Checked by:

, Date:

Approved by:

Date:

8; a

t Comment:-

1 Aquifer Test Data (Page 2 of 3) a) Use of Test Procedures - Slug-test arocedures require "the decline or

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recovery of. water level [to be] measure:d] at repeated closely spaced intervals during the ensuing minute or two" after cessation of pumping (Lohman,1972). However, the staff noted that a delay of greater than two minutes was realized during testing of several wells.. For example, a delay of six minutes occurred prior to measuring water levels when well # 586 was tested. These delays may have resulted in the loss of important data points needed for analysis.

DOE should evalucte and-address the potential impact of delays on the validity of the data and the results-obtained from the slug and recovery test analyses.

b) Uso of Data Analyses Methods -'One aquifer test was performed on each of the wells completed in the lower-middle.and. bottom hydrostratigraphie units. The resulting data were-then analyzed by recovery and' slug test methods. However, these two methods require data that are collected using different test procedures.

For example, slug test analyses require an insta'ntaneous removal or addition of water while aquifer recovery tests involve a longer period of water pumping.

Because the pumping portion of 4

these tests were conducted for several minutes,.NRC staff request that DOE consider whether the slug test method is appropriate for analysis of the data obtained.

If slug. test analyses are used to support characterization of the aquifers, DOE should evaluate the uncertainties associated with use i

of this data and address the potential impact on the results to be presented in the final RAP and final EA.

c) Uncertainties in Results - As stated by Lohman (1972), use of the slug test for unconfined aquifers "... would require considerable i

judgement, and the results should be' regarded with skepticism." DOE used the slug test on several wells in the unconfined alluvial material on Brown's Wash, but have not apparently addressed the potential errors associated with its use.

In addition, Ferris'and Knowles (1962) stated that "because the coefficient of. transmissibility li.e. hydraulic ~ conductivity]

determined from this [ slug] test generally a[ plies only to the material close to the well, indiscriminate use of the results can lead to erroneous conclusions." Therefore, DOE's interpretation that the hydraulic conductivity results are representative of the material in the study area-may introduce considerable error in assessing long-term impacts.

In development of the final EA and final RAP, DOE should evaluate the errors and uncertainties associated with these slug test.results, and-consider these errors in-assessment of the long-term impacts on ground water.

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Comment:

1 Aquifer Test Data (Page3of3) i d) Results of Calculations - The " Aquifer Test Data Form," provides the rate and duration of pumping for each aquifer test.

Based on this data, the accompanying graphs show the total volume of water removad during the test. This information is important because it is used to c-ite hydraulic conductivity. However, using the initial and fi tr level measurements reported during pumping and the radius of eaci NRC staff calculate the volumes of water removed from the wells to br.

ficantly different than the volumes shown in the graphs. MRC staff request that DOE resolve the apparent inconsistencies prior to completion of the final RAD and final EA.

1 In sumary, hydraulic conductivity is an important aspect of site characterization since it may significantly influence potential impacts on the long-term quality of ground water. Therefore aquifer test data need to be carefully collected and analyzed, using appropriate procedures and accounting for uncertainties, in order to assure that the hydraulic conductivity values resulting from these data are accurate. DOE should evaluate the potential l

uncertainty of the hydraulic conductivity values presented in the DEA and reflected in the dRAP, based on review of the test data supporting these values, to address the staff's concerns in development of the final EA and final RAP.

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References Lohman, S.W., 1972, Ground-Water Hydraulics, U.S. Geological Survey Professional Paper 708, U.S. Government Printing Office, Washington, D.C.

Ferris, J.G. and D.B. Knowles,1962. The Slug-Injection Test for Estimating the Coefficient of Transmissibility of an Aquifer, In Methods of Determining Permeability, Transmissibility and Draiiidown, U.S. Geological Survey Water Supply Paper 1536,-I.

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UMTRA DOCUMENT REVIEW FCRM SECTION 1 Site: Green River, Utah Date: May 28, 1987 l

Document: Information Supporting the dRAP and DEA Commentor: NRC Staff / Geology Comment:

2 DOE's DEA states that the Dakota Sandstone is a barrier to ground water 3

movement (page B-57) thus protecting hydrostratigraphic units in the underlying l

Cedar Mountain Formation. However, based on continuing discussions between o

NRC and DOE site geologists, the NRC staff question the extent of the Dakota.

In addition, elsewhere in the Colorado Plateau, Dakota Sandstone is an aquifer providing a considerable ground water resource (Cooley and others, 1969).- If 1

Dakota Sandstone is discontinuous beneath the site, a hydrogeologic barrier is

' lacking and protection of ground water resources could become a concern. DOE should provide evidence that the Dakota is indeed an aquiclude at the site and that it is continuous beneath the proposed disposal site.

Reference Cooley, M.E. Harshbarger, J.W., Akers, J.P., and Hardt, W.F.,1069, Regional hydrogeology of the Navajo and Hopi Indian reservations, Arizona, New Mexico, and Utah: U.S. Geological Survey Professional Paper 521-A, 61 p.

SECTION 2

Response

Page By:

Date:

Plans for Implementation:

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SECTION 3 Confirmation of Implementation:

Checked by:

, Date:

Approved by:

, Date: