ML20198M730

Forwards Comments & Questions Re Review of Mexican Hat Draft Remedial Action Plan

ML20198M730
Person / Time
Issue date:	05/06/1986
From:	Fliegel M NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
To:	Hawkins E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
REF-WM-63, REF-WM-70, TASK-TF, TASK-URFO NUDOCS 9710290093
Download: ML20198M730 (3)

Text

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1. %j UNITE) STATE: h/b 63 NUCLEAR REGULATORY COMMISSION A wAsmNoToN, p. c. rores S * *

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Ed Hawkins, URF0 MEMORANDUM FOR:

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f FROM: Myron H. Fliegel, Section Leader g u. : # .'?'

Hydrology Section, WMGT , .(p

SUBJECT:

REVIEW OF MEXICAN HAT DRAFT REMEDIAL ACTION PLAN In accordance with your recent requests, Ted Johnson has completed a review of-the subject remedial action plan. Our comments and questions are enclosed.

O eieese note 18et our rev4ews were verformed ie eccordence with sour instructions to treat these documents as preliminary, conceptual documents. We reviewed them to identify any fatal flaws and serious problems with the overall

" conceptual" design.

If you have any questions, please c tact Ted_ Johnson ~427-4490.

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M on H. F1 egel, Section Leader Hydrology Section, WMGT

Enclosure:

As Stated Or

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i Mexican Hat DRAP

Surface Water Hydrology and Erosion Protection Questions and Comments Additional information should be provided regarding the erosion protection

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1.3 designs that are proposed to prevent headcutting and erosion of the numerous gullies-and arroyos at the site.. At the present' time, it is not clear what types of designs will be used and how these designs will be

. implemented. Preliminary designs should be provided to show depth-to

-bedrock and-the general configuration of the erosion protection as it is

. 3 keyed intoithe rock; these preliminary designs are needed in order to' .

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' determine the overall feasibility of the remedial-action, particularly for the gullies and arroyos that have large drainage areas.and/or have very steep slopes; ,

4 Information should include the following:

< a~ gulkyconfigurationandcross-section-b .' -drainage area c.; riprap. design to be used

d. depths to bedrock at each gully ,

2. Preliminary designs should be provided regarding the proposed diversion +

s channels and other natural channels at the site. Information is needed for. each channels, as follows:

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a. channel.' width, shape, and/or cross-section- [

channel slope

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c. drainage area

+ d. -PMF peak flow estimate

-e,- :PMF velocities f.. riprap requirements 9 riprap toe requirements

h. exit velocity, exit design, and depth to bedrock at exit point.

3. The NRC staff does not necessarily agree with-the rock durability criteria outlined in DOE's Technical Approach Document (TAD), and-does not agree. <

that-.these criteria are acceptable. In general, the criteria in the TAD are much-less stringent than:other normally acceptable criteria, such as -

the USBR criteria for good-quality rock. However, we do agree that oversizing may-be a viable-alternative arrd can only be evaluated after additionalJdurability; tests are performed; 1

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. Based on the preliminary ~ data prov.ided it does not appear that:the rock.

.will meet USBR criteria for even poor-quality' rock. . We suggest that

-additional-efforts'be performed to locate rock-of better quality. If=

- such rock cannot be found. DOE should indicate the methods and criteria-

c , 1that will.-be used to oversize the poor-quality rockLthat is available.

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