ML20140E260
| ML20140E260 | |
| Person / Time | |
|---|---|
| Issue date: | 03/13/1986 |
| From: | Hawkins E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Themelis J ENERGY, DEPT. OF |
| References | |
| REF-WM-64 NUDOCS 8603270394 | |
| Download: ML20140E260 (7) | |
Text
DISTRIBUTION O
DQcket. File WM-MI-PDR/DCS a
WM-181/TT0/86/03/06/0 n PGarcia RBrich HRose MAR 13 E FMiera, OR LLW Branch, WMLU URF0 r/f URFO:TTO TJohnson, WM Docket No. WM-181 040WM181601E John G. Themelis, Pridect Manager Uranium Mill Tailings Project Office Albuquerque Operations Office U.S. Department of Energy P.O. Box 5400 Albuquerque, New Mex.ico 87115
Dear Mr. Themelis:
NRC's Uranium Recovery Field Office has 2cmpleted a preliminary review of the documents entitled " Main Constructiott Subcontract - Subcontract Documents LKV-1, Final Design for Review " and Calculations Volumes I, II, III, and IV.
I have enclosed our specific comments on this bid package.
In summarizing the enclosed comments, the issues we have identified that will require resolution are in the areas of the design of erosion protection, the radon barrier material, modifications to the design due to incorp'brating a wood chip encapsulation cell, changes to the processing site retention pond, and rock durability testing.
Our review has been somewhat hampered by the large number of changes that
~have been made in the design since we reviewed the RAP and a significant amount of information that was missing from the submittals. We feel that the purpose of the NRC review of a bid package is to aid in " fine tuning" the design, major aspects of which have previously been agreed upon during the review of the RAP.
However, our review of the bid package indicates-that major revisions are continually being incorporated into the design. We feel that the issuance of the bid package in this instance is premature. Also, since the changes that were proposed as a result of your Value Engineering exercise are not included in these submittals, additional review of those items will be required prior to final concurrence.
Q g 860313 WM-64 pg 0FC :
NAME :
DATE :86/03/13
WM-181/TT0/86/03/06/0 MAR 13126 Should you have any questions, please contact either Thomas Olsen on FTS 776-2813 or me.
Sincqrely, W!r' 'al E'f 7 M I*f re :.rJ 7. Hana1 Edward F. Hawkins, Chief Licensing Branch 1 Uranium Recovery Field Office Region IV
Enclosure:
As stated i
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NRC REVIEW COM4ENTS ON LAKEVIEW SUBCONTRACT DOCUMENTS AND CALCULATIONS
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General 1.
Contents page 3, Collins Ranch Disposal Site The drawing contiining the contaminated wood chips encapsulation cell should be Drawing 1323, not 1322.
2.
- p. 02140-1, 1.2.A Uncontaminated and contaminated areas (both water and soil) should be delineated uising a systematic approach or test procedure.
Please expand on the recommended procedures and indicate how verification of results will be accomplished.
3.
Section 02200
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DOE presented engineering plans for,the contaminated wood chip cell at the Value Engineering Study meeting on February 11, 1986.
The Subcontract Document does not reflect this new design modification.
DOE will need to show engineering documentation pertinent to the modification in6orporating-the contaminated wood chip cell, including all construction specifications.
Also, DOE's February presentation showed that the tailings encapsulation structure and the wood chip cell were to be separate.
However, the subcontract drawings show the two cells to be contiguous.
This will require submission of additional information to document that the wood chip cell will not adversely impact the main tailings cell or revision of the drawings to clearly indicate that the cells are to be separate.
4.
Section 02200 Review of Section 3.4 indicates that the " Tolerances" section has been omitted.
Please state the design tolerances for the materials discussed in this section (i.e., liner and radon cover).
If the tolerances are as specified on p. 01052-3, the section should be reproduced or at least referenced in Section 02200.
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2 5.
- p. 02200-7, 1.7.C.
Tests performed on the radon barrier material for specific RAECOM input parameters should be submitted to the NRC for review and approval. NRC still does-not accept a 1.5-foot thick radon barrier cover thickness based on currently available data.
6.
Section 02200-11, 8.2
.3
-During seasonal shutdown it is unlikely that seeding will be adequate and/or will even be established in such a short period of time to control erosion of tailings.
The specifications should require placement of an earth cover to stabilize tailings areas during periods of extended shutdown.
7.
- p. 02200-12, 8.6 TheconstructionofthegeochemicaI'flowbarrierisdiscussedin Article 3.7, not,3.8 as referenced.
8.
There is a contradiction in the foi,fowing two references:
- p. 02200-17, B.1 Compactionfof liner to 90% of ASTM D698.
- p. 02200-19, C.1 Compaction of liner to 95% of ASTM D698.
The specifications in Section B.1 should be revised to show compaction to 95% of ASTM D698.
9.
- p. 02200-19, C.2 Last two sentences are contradicting with regard to moisture content of liner soils.
10.
- p. 02278-4 No specifications are given for rock durability testing during placement to document that the quality of the rock continues to be acceptable.
A minimum acceptable program would require testing whenever the quality of the rock appears to change, but at least at the one-third and two-third points based on total volume to be placed.
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3 11.
- p. 02278-4 This section specifies that the Contractor will review the results of the petrographic examination.
NRC will require that the results of the petrographic examination be submitted for NRC review.
12.
Section 02771 At the Value Engheering Study meeting held on February 11, 1986 at the URF0 office, DOE stated that the processing site retention pond liner may be eliminated.
If DOE intends to eliminate the processing site retention pond liner, pertinent engineering documentation will be required to support such modification.
Our initial reaction is that elimination of the liner would not be in compliance with EPA (and possibly state) standards.
OffPileExcavationLimitsandQuantities-Calc.No. 13-726-01-01.
(Volume IV) 13.
Reference 14 is missing from sheet a-1.
The reference refers to additional information supporting the suitability of excavation control using Th-230 content limits.
Reference 14 is the response to TAC comments'.by MKE.
Review of the responses on sheet 11 (item 127.3) indicates that. field measurement techniques for Th-230 are to be established.
Please provide these techniques to NRC prior to implementation.
Hydrology and Erosion Protection 14.
Our review indicates that the rock layers for i.he rock apron at the toe of the embankmont side slope and for the energy dissipation area (EDA) at the downstream end of the diversion ditch have both been designed assuming that normal depth and velocities will occur.
In the upstream portions of the apron and the EDA, this assumption may not be valid because normal flow depths will likely be established only at some point downstream (after the flow has had the opportunity to stabilize).
A considerable amount of turbulence and energy dissipation can be expected to occur in upstream sections.
Because the main purpose of the apron and EDA is to dissipate the energy produced on the steeper upstream slopes, these areas should be designed under the basic premise that they will act as stilling basins.
It may be necessary to increase the average rock sizes and layer thickness in these areas, particularly on the upstream
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4 portions of the apron and EDA where most of the energy will be dissipated.
While we recognize that specific guidance for designing erosion protection in energy dissipation ar'eas may not be available, a redesign of the apron and EDA should be performed.
Use of the following will provide designs which are acceptable to the NRC staff:
l a.
EM 1110-2-1603, " Hydraulic Design of Spillways" (page 45),
indicates that erosion protection in turbulent areas should be designed assuming that the stability of the rock layer is dependent upon the stability of an individual average rock in the layer., Use of the isolated cube curve and the average velocity produced on the steeper upsteam slope (as shown on Plate 22) is acceptable for oesigning rock on the apron and EDA.
b.
ETL-1110-2-f20 " Additional Guiddnce for Riprap Channel Protection"'(page 4) indicates that where uniform channel flow does not occur, local shear fo'rces will be greater than indicated by normal computational methods, and that shear forces should be increased by a factor of about 1.5 to account for localized velocities and pressure pulsations.
Use of this factor, basbd on the velocity on the steeper upstream slope, is acceptable for designing the erosion protection for the apron and the EDA.
(See also Question 15, below.)
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- 15. We note that credit has been taken for flow through the rock layer i
in the diversion ditch.
In the steeper ditch segments, this can amount to a significant percentage of the total flood flow.
For example, in ditch segment D-5, the flow through the rock layer was computed to be about 120 cfs out of a total of about 300 cfs.
As a I
result, the riprap in this ditch segment has been designed to i
withstand a flow of about 180 cfs.
However, it must be realized l
that at some point at the downstream end of this ditch segment (where it merges with the EDA), the entire flow will emerge onto the face of the rock layer.
At this point, 300 cfs (not 180 cfs) l becomes the design flow.
Where the slopes change from a steep to a mild grade, such at the apron and EDA, the calculations should be revised to reflect the larger flow rates occurring over the top of the rock layer.
It should be recognized that the exact location of the occurrence of emergent flow may be very difficult to determine.
General guidance may be found in Rockfill in Hydraulic Engineering (D. Stephenson, 1979).
Lacking specific or reliable estimates, the rock should be
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designed for the larger flow rate for a distance of at least 20 feet upstream of the slope breaks at the apron and the EDA.
Downstream of the slope breaks for about 20 feet, the increased flow rate and revised velocity should also be us p to design'the erosion protection.
(See Question 14, above.)
16.
The key trenches at the downstream end of the apron and EDA are proposed to be appro>imately 3 feet deep and have a cross-section that is approxim4tely square.
Since the trenches do not key into rock, the NRC staff do_es not consider this design to be acceptable in meeting EPA long-term stability standards.
First, the deoth of the key trench snould be greater than 3 feet.
Examination of an existing gully (which the proposed pile will cover) in the site area indicates tnat this gully is more than 3 feet deep.
Since it is likely that a gully will form and headcut gradually toward the downstream end.pf the apron and EDA, it would seem prudent to p. lace the key trench?st a depth at least as deep as the inaximum depth of the existing gully (if the drainage area of the assumed new gullf will be significa gly different from the drainage area of the existing gully, adjustm'ents will need to be made accordingly).
Second, the square trench cross-section proposed raay not be adequate to provide an adequate qua.itity of rock to make the future gully-l "sel f-heal ing. " The cross-sections should be revised to reflect standard practice, such as EM.1110-2-1601 (Plate 38) which provides acceptable guidance for design or riprap end protection.
(Method C provides one acceptable method.) Alternate des:gns, if tsed, should be thoroughly documented.
The design of the key trenches should be revised, as necessary.
Wood Chip Encapsulation Cell 17.
Engineering calculations need to be provided for all aspects of the wood chip encapsulation cell design, including t?esfollowing:
embankment design, settlement, site drainage, erosion protection, l
and the estimated volume of material.
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