ML20137B989
| ML20137B989 | |
| Person / Time | |
|---|---|
| Issue date: | 10/28/1985 |
| From: | Higginbotham L NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Themelis J ENERGY, DEPT. OF |
| References | |
| REF-WM-58 NUDOCS 8601160155 | |
| Download: ML20137B989 (5) | |
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Mr. John G. Themelis, Project Manager Alems s/f4 RE Browning J. Valdes UMTRA Project Office WMLU r/f' MJ Bell M Blackford U.S. Department of Energy NMSS s/f M Fliegel M Larson P. O. Box 5400 DM Gillen P Justus Ted Johnson Albuquerque, New Mexico 87115 DE Martin M Nataraja J0 Bunting M Tokar
Dear Mr. Themelis:
B Jagannath M Weber We have completed a review of the information provided in your letter of September 6,1985 that responded to our previous coninents on construction specifications, and to the four conditional concurrence issues for the Shiprock, New Mexico remedial action plan. contains remaining staff observations on DOE's responses to our comments on construction specifications. Two modifications to the specifications are suggested for D0E's consideration. These areas will receive NRC attention during future on-site construction reviews. Enclosure 2-updates the status of the four conditional concurrence issues. Note that the information provided by DOE has not yet closed any of these issues.
Should you have any questions regarding this transmittal, please contact me or Daniel Gillen of my staff.
Sincerely, Original siendi by leo B. Higginbh Leo B. Higginbotham, Chief Low-Level Waste and Uranium Recovery Projects Branch Division of Waste Management i
Office of Nuclear Material' Safety and Safeguards
Enclosures:
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I OCT 281985 E!! CLOSURE 1 GEOTECHNICAL ENGINEERING OBSERVATIONS ON DOE'S RESPONSES TO NRC'S COMENTS ON SPECIFICATIONS FOR PHASE II CONSTRUCTION, SHIPROCK RAP f
The DOE's responses to consnent numbers 1, 4, and 5 are satisfactory; NRC's observations on DOE's responses to cosinent numbers 2 and 4 are presented below.
1.
Comment Number 2 - Radon Barrier Materials (Section 02200, Earthwork, Part 2 - Products, Section 2.2.B. Page 02200-3)
The NRC's comment was that the specification is not restrictive; a gap-graded material which satisfies the percent fine criteria will be in compliance with the specification.
In the specification there is no limit on the maximum size of particles. There is no statement on prohibiting gap-graded material, but there is a statement that mixing may be needed to meet the percent fine r
criteria. The DOE's response shows that the test samples from designated borrow areas satisfy the specification, and the data from tests on these samples are used in the design of earth cover as radon barrier. But the NRC l
concerns on lack of maximum size and gradation requirements in the specification are not addressed in the response. Even though the limited laboratory samples do comply with the specifications and provide proper gradation, there is nothing in the specification to assure that similar materials will be used in the field. The specification may be revised to address the above concern.
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2.
Coment Number 3 - Relocation and Compaction of Slime (Section 02200, Earthwork, Part 3 - Execution, Section 3.2, Page 0220-7) l The specification, items 3.2.A.7 and 8, states that pockets of slime located in tailings designated to be relocated or otherwise disturbed shall be mixed with sands and placed at the lower part of the tailings embankment. The DOE's response, to NRC's question seeking guidelines for mixing with sand, was that mixing with sand was required only for construction purposes.to support the-l equipment and not for radon attenuation. The' response further states that the l
subcontractor will be allowed the option of drying the slime rather than mixing with sand and compacting it to the specification. The NRC concurs that radon attenuation should not be the intent for mixing slime with sand. The intent l
was to improve the stability / strength characteristics of the material. The
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slime and sand, both compacted to meet specification (compacted to a dry 1
density of 90 percent of maximum dry density as per ASTM D698 method) will have
-l different dry density, strength, and compression characteristics.
In the j'
absence of mixin with sand, it is possible to end up with a large pocket of compacted slime several layers of slime, within a small area, compacted to meet specification) and compacted sand next to each other. This has the potential to result in uneven settlement under the weight of the overburden i
fill and radon barrier cover. To mitigate this problem, a desirable solution would be to distribute the slime evenly over the embankment area to prevent the i
possibility of uneven settlement. Another solution is to place the slime and sand in alternate layers so that the slime would readily stabilize aided by the sand layers in dissipating the excess pore pressures in the slime. The possibility of relocating and compacting slime will be at all UMTRAP sites; the specification may be revised to address the above concern.
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- 1 QCT 28 n85 ENCLOSURE 2 STATUS OF SHIPROCK CONDITIONAL
. CONCURRENCE ISSUES CONDITION 1: Characterization of Groundwater in San Juan Alluvium DOE's response to this concurrence condition does not resolve the condition, but rather describes how DOE will attempt to resolve the contamination issue.
As noted in DOE's response, Michael Weber and John Price (DOE's Technical Assistance Contractor) discussed DOE's proposed drilling program and agreed.
that the proposed program of monitoring well installation and associated water quality sampling constituted a reasonable approach to develop the necessary field information to characterize groundwater contamination in the alluvium.
DOE should submit information pertinent to closure of this condition after it has installed the proposed monitoring wells, characterized groundwater quality in the alluvium, and selected appropriate actions (if:any) to control or -
mitigate the groundwater contamination. Without such information, we are unable to resolve the issue of groundwater contamination in the San Juan River floodplain.
When this information is submitted, it should ' include a detailed map showing the locations of the monitoring wells on the floodplain. The scale of the map l
provided as Figure 2 in the Statement of Work for additional site characterization is inadequate to accurately locate the proposed monitoring i
j locations.
In addition, DOE should note that monitoring wells in alluvium on l
the north side of the San Juan River are necessary to determine whether the river prevents contaminant migration from the Shiprock site in groundwater north of the river. DOE's response implies that these wells would only be useful to characterize background groundwater quality in the alluvium.-
CONDITION 2: Erosion Protection Design A request for additional information has been transmitted to DOE by letter dated October 15, 1985, and telecopied to the RAC.
In pursuit of resolution of this issue, T. Johnson of the NRC staff will meet with T. R. Wathen and J.
l Thiers of the RAC during the week of _ Octobe'r 28, 1985.
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. CONDITION 3: Characterization of Seismotectonic Hazard.
The present DOE response does not satisfy this concurrence condition, but describes how DOE proposes to do so. At the September 27th DOE-NRC Group II (Geotechnical Stability) meeting TAC staff indicated that'the information submitted for review has been superseded by the September,1985 Seismic Hazard Assessment chapter of DOC's UMTRAP Design Manual, which will govern the scope of DOE investigations at Shiprock as well as other sites. Review comments.
pertaining to the latest version of this Seismic Hazard Assessment chapter are being transmitted to DOE / TAC in a separate letter. The NRC staff will pursue closure of this condition when the results of the Shiprock seismic hazard assessment are submitted for review.
CONDITION 4: Radon Barrier Design As indicated by NRC le'.ter to DOE' dated September 5, 1985, NRC concurrence in the Shiprock radon barrier design remains open until 'we can review and approve a revised design which applies either a more reliable. diffusion coefficient based upon additional testing of the cover material, or a more conservative diffusion coefficient based upon the existing data. The present response indicates that additional tests are to be performed. The staff will pursue closure of this issue upon DOE's submittal of the data.
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