ML20236T469
| ML20236T469 | |
| Person / Time | |
|---|---|
| Issue date: | 11/05/1987 |
| From: | Johnson T, Starmer R NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Surmeier J NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| REF-WM-58 NUDOCS 8712010274 | |
| Download: ML20236T469 (3) | |
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[liEiura toVICE55f W/~ 1 MEMORANDUM FOR: John J. Surmeier, Chief [
Technical Branch Division of Low-Level Waste Management and Decommissioning, NMSS FROM: Ted L. Johnson Technical Branch Division of Low-Level Waste Management and Decommissioning, NMSS R. John Starmer, Section Leader Technical Branch Division of Low-Level Waste Management and Decommissioning, HMSS
SUBJECT:
SITE VISIT TO SHIPROCK, NM REMEDIAL ACTION SITE On October 21, 1987, site observations were conducted by NRC, DOE, and Jacobs Engineering staff at the Shiprock, NM remedial action site. The purpose of the site visit was to observe completed features of the design to verify that the construction had been done in accordance with statements made by DOE in the completion report.
Attendees at the site visit were:
T. Johnson, NRC J. Starmer, NRC M. Nelson, Jacobs Engineering D. Leske, DOE M. Abrams, DOE I The principal site features which were observed included the erosion protection for the top and sides of the pile, the diversion ditches surrounding the pile, and the energy dissipation area at the downstream end of Ditch D-7. During a walkover of the entire site, the features were compared with as-built drawings and construction specifications as given in Vol. 2A of the completion report.
A. Exposed Bedding Layers In general, our observations indicate that the erosion protection may not have i
been constructed in accordance with the' plans and specifications. We noted that bedding material and/or fines are exposed in many locations at or within several inches of the surface of the rock. The presence of fines at these locations would seem to indicate that one or more of the following situations exist:
8712010274 871105 PDR WASTE
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. UM-58 PDR
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NOV 0 51987 ,
John J. Surmeier 2
- 1. Twelve (12) inches of Type A or Type B riprap has not been placed at 4 these locations, as required. !
- 2. A riprap layer which does meet thickness requirements is covered or partially obscured by bedding material and/or fines.
- 3. During construction, the riprap has been pushed into the softer bedding layer by heavy equipment.
- 4. During construction, heavy equipment moved correctly-placed riprap to other areas, thus causing some areas to be too thick and other areas to be too thin.
It should be emphasized that the fines were exposed at many locations, and such exposure was not an isolated instance. The problem is highlighted in many areas by the presence of vegetation; however, there are many locations where the bedding is visible, but vegetation has not yet sprouted.
We attempted several times (without the use of equipment) to determine if there was adequate riprap underlying the exposed fines. At several locations, the amount of rock appeared adequate; in other locations, it did not. In several locations, it appeared that the rock had been forced by heavy equipment into the bedding layer. Two points should be emphasized regarding the placement of the rock:
- 1. The rock layer is probably thin in many areas.
- 2. Where the rock layer is thin, or absent, for whatever reason, construction specifications have not been met.
B. Uneven Placement of Rock There were many areas where the rock layer was much thicker than required and many areas where the rock appears to be not as thick as required. This problem may be related to exposed fines obscuring properly-placed riprap in many instances; however, there were some areas where there appears to be insufficient rock thickness. The most apparent examples occurred in Ditch D-7 and along the southeast portion of the pile where the top slope meets the side slope. The problem may have been caused in many cases by heavy equipment which moved riprap of adequate thickness to other areas, causing some areas to be too thin.
C. Rock of Inadequate Size Overall, the average rock size appeared to be more than adequate. However, portions of ditch D-7 appeared to have rock which did not meet minimum size l requirements of approximately 5-6 inches. This problem is in addition to the l l problems identified in A and B, above. !
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,Q NOV 0 51987 John J. Surmeier- 3 D.:Close-Out Exit Interview Following the s'ite observations, discussions were held regarding the problems identified above. NRC, DOE, and Jacobs staff agreed that there definitely, appeared.to be several problems with the placement of the rock. It was also, agreed that the best course of action to resolve the problem would be to l conduct detailed inspections-to determine the adequacy of the erosion protection. We agreed that the inspections should be conducted by a team of
- technical and construction experts, with a work crew available to do any digging and rock movement which may be required to determine if the required rock had been placed.
Ori6 1nal S16ned By Ted L. Johnson Technical Branch Division of Low-Level Waste Management and Decommissioning, NMSS Original Si6ned By R. John Starmer, Section Leader Technical Branch Division of Low-Level Waste Management and Decommissioning, NMSS DISTRIBUTION:.
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