ML20236T725

Forwards Geotechnical Engineering Review of Preliminary Design Documents Re Umtrap,Green River UT Site for Sept 1987,per Recipient Request for Review.Requests Listing of Changes Made to Preliminary Design Documents at Each Stage

ML20236T725
Person / Time
Issue date:	10/28/1987
From:	Tokar M NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
To:	Fliegel M NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
References
REF-WM-68 NUDOCS 8712020055
Download: ML20236T725 (4)

Text

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MEMORANDUM FOR: Myron Fliegel, Section Leader _ _ . _ _ t f_ . _

Operations Branch -

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Division of Low-Level Waste Management i-and Decommissioning, NMSS

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FROM: Michael Tokar, Section Leader ,

Technical Branch 3 Division of Low-Level Waste Management' ' -M and Decommissioning, NMSS  !

SUBJECT:

GE0 TECHNICAL REVIEW 0F THE PRELIMINARY DESIGN DOCUMENTS AND SUBCONTRACT DOCUMENT, UMTRAP, GREEN RIVER, UTAH, SEPTEMBER 1987.

At your request, the geotechnicai engineering aspects of the Preliminary Design and Specifications for the remedial actions at the Green River site have been briefly reviewed. Because of the quick response requested by the DOE and previously committed work to be completed by the reviewer, it was agreed with the Project Manager that only a fatal flaw review should be I performed before the due date and a detailed review should be completed during January 1988. Our fatal-flaw-review comments are attached to this memo.

The preliminary design for the tailings embankment prepared by the RAC/D0E is different from that presented by the TAC / DOE in the Remedial Action Plan, and although the changes are an improvement in the design, it would be very helpful if the preliminary design documents identify or list up front all the {

changes made since the previous submission. This would be helpful particularly i to new reviewers. I suggest that LLOB consider requesting the DOE to comply with this request for all future submissions.

This review was performed by Dr. Banad Jagannath; please contact him should you have any questions.

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Michael Tokar, Section Leader  ;

Technical Branch '

Division of Low-Level Waste Management and Decommissioning, NMSS

Enclosure:

As stated DISTRIBUTION:

LLWM/5F BJagannath NMSS r/f MTokar RJStarmer LLTB r/f JJSurmeier SBilhorn 0FC :LLTB  :  :  :  :  :  :

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$AME:BJaga'nah :MTokar  :  :  :  :  :

@ ATE :10/21/87 :10/M' /87  :  :  :  :  :

0FFICIAL RECORD COPY 8712020055 871028 PDR WASTE WM-68 PDR l c.

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URANIUM MILL TAILINGS REMEDIAL ACTION PROJECT (UMTRAP)

GREEN RIVER, UTAH

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GE0 TECHNICAL ENGINEERING REVIEW 0F PRELIMINARY DESIGN DOCUMENTS l

j Review by: Banad Jagannath, LLTB Documents Reviewed: 1. Green River Subcontract Documents-Specifications, and Subcontract drawings; dated 9/87

2. Green River Design Calculations, Vol. I, II, and 111; dated 9/87 REVIEW COMMENTS

1. Drawing GRN-PS-10e0517, REV A The remediated tailings embankment is proposed to be founded on the bedrock, a highly fractured shale of the Cedar Mountain formation. Tailings are proposed to be placed (compacted) directly on top of the bedrock. There is no provision for collection and appropriate disposal of any contaminated water >

collected in the foundation excavation during construction. The present design permits all the water in the excavation to drain down and ultimately reach the groundwater.

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The proposed riprap protection for the toe of the tailings pile has the I potential for water seeping through the riprap and fractured rock and into the i

tailings pile. The design detail at the intersection of the riprap and top of '

bedrock, as presented in the drawing, permits the water to come in contact with the tailings and drain down the fractured bedrock and ultimately come in contact with the groundwater.

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! Geology and groundwater comments on this aspect of design should also be considered in responding to this comment.

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2. Drawing GRN-PS-10-0518. REV A 1

The' drawing'shows monitoring wells, well points and bore holes, although the title indicates only monitoring wells need to be abandoned (plugged). There

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are many well points at this site and some of them may have to be plugged.

This drawing needs to be revised to indicate any well points which have to be plugged. j i

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3. Specifications, Page 02200-3, Item 1. Subgrade Preparation This item does not cover preparation of the subgrade'for placing the tailings material in the foundation excavation in the bedrock. Is there any control on the tolerance for excavating (ripping) in the bedrock?

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4. Specifications, Page 02200-8, Item B- Radon Barrier Material The specification should be revised to limit the maximum size of the particle i permitted for the radon barrier material. The current specification requires 4

that a~ minimum of 50 percent of the material pass through #200 sieve and there is no other requirement. This may result in a gap graded material which will exhibit a coefficient of permeability higher than that for a well graded l material both with a minimum of 50 percent passing through # 200 sieve. The gradation specification should be revised to ensure that the material placed  !

as the radon barrier cover is similar to that tested to determine the coefficient of permeability values used in the design.

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5. Specifications, Page 02200-12, Item 3.3 B- Contaminated Material Excavation l J

The draft RAP assumed that the tailings embankment will be constructed by placing the highly contaminated tailings at the bottom of the pile and less contaminated material at the top of the pile. The preliminary design, j

however, assumes no layering within the tailings pile and thereby implies that the

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level of contamination is not a factor in deciding on the location and I placement of tailings within the embankment. The current specification states ".... and placed in proper part of the tailings embankment ...... "

implying an intent to place the tailings selectively within the embankment.

The specification should be clear if selective placpent is the intent.

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6. Specifications Page 02200-18, Item 3.6 B- Field Quality Control Tests l t

The test frequency for in-place density tests on the subgrade should be one per ,

1500 sq. yds area rather than one per 5000 sq. yds as stated in the specifications. The test frequency should comply with the provisions of the forthcoming Remedial Action Inspection Plan for this site.

! 7. General Cort erns The staff sas not reviewed the following item in detail but would like to ,

bring t' <s to the DOE's attention.

1 The long-term moisture content of the tailings and radon barrier material are determined based on minimal test data. The in situ moisture content of the materials are lower than the long-term moisture content  !

used in the design calculations. The DOE should perform appropriate tests and calculations to justify the value of the long-term moisture contents used in the radon barrier design calculations.

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