ML20209H785
| ML20209H785 | |
| Person / Time | |
|---|---|
| Issue date: | 07/02/1986 |
| From: | Justus P NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Knapp M NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| REF-WM-68 NUDOCS 8609150355 | |
| Download: ML20209H785 (3) | |
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WMGT r/f jut. 2 1986 MMss r/f fiEliO/ GREEN RIVER /TJ/86/06/30 RBrowning MBell JBunting PJustus MEPORANDUM FOR: Malcolm R. Knapp, Acting Chief TJohnson & r/f WMLU MFliegel PDR EHawkins, URF0 FROM: Philip S. Justus, Acting Chief GGnugnoli, WMLU WMGT i
SUBJECT:
REVIEW 0F GREEN RIVER, UTAH DRAFT CADSAR In accordance with discussions held between Giorgio Gnugnoli and Ted Johnson, we have completed a brief review of the surface water hydrology and erosion protection aspects of the subject Draft Comparative Analysis of Disposal Site Alternatives Report (CADSAR). Our comments (which are written in an abbreviated style, as agreed in our discussion with Giorgio Gnugnoli), are enclosed. Based on this review, we conclude that the CADSAR is not adequate to support the conclusions that have been reached. We recomend that DOE re-examine the intent and purpose of CADSAR's and that this CADSAR, in particular, be modified to include sufficient data and analyses to support the findings. Additionally, we recommend that the CADSAR site selection process be expanded to include more than one or two alternatives.
This review was performed by Ted Johnson. If you have any questions, he may be reached at extension 74490. I
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Philip S. Justus, Acting Chief WMGT
Enclosure:
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\ d GREEN RIVER, UTAH DRAFT CADSAR SURFACE WATER HYDRCLOGY QUESTIONS AND COMMENTS
.1. Based on a review of the information provided in the CADSAR, it does not appear that the erosion protection requirements for either the stabilization-in-place (SIP) option or the stabilization-on-site (SOS) option have been adequately estimated. For the SIP option, it appears that extensive riprap will be needed along Brown's Wash. For the SOS option, it appears that extensive riprap will be needed both on Brown's Wash and on the slopes which direct runoff from the pile to the Brown's Wash floodplain.
While the information provided in the CADSAR is not complete regarding flood flows and velocities, it appears that because of the stream's alignment, flooding on Brown's Wash will likely cause considerable erosion by directing flood flows essentially perpendicular to the stream bank. For both the SIP and SOS options, crosion protection will be needed to prevent streambank erosion; and to prevent migration of the channel toward the relocated tailings. Additionally, for the SOS option, it appears that the slopes from the proposed pile to the ficodplain are relatively steep (IV on 5H) and will thus require erosion protection to stabilize them. The situation and problems posed here may be similar (but on a smaller scale) to those at the Shiprock, New Mexico site where escarpment stabilization and flow diversions using extensive erosion protection were required.
We conclude that additional studies should be conducted to better assess the erosion protection designs for the two options presented.
These studies should include an assessment of (1) PMF peak flows, velocities, and erosion protection for Brown's Wash and; (2) the need for erosion protection for slopes where the SOS option is used.
Based on the above, it may be prudent to discuss the viability and costs associated with one or more additional alternative sites. '
- 2. In general, those factors which significantly affect the design should be carefully analyzed in the CADSAR. Recognizing that the CADSAR is a preliminary decision-making document, it is noretheless important to provide estimates of the erosion protection (for example) that will be needed, since this aspect constitutes a large percentage of the total costs at a site like Green River. We consider that preliminary estimates of the PMF peak flow and velocity should have been stated in the CADSAR, in order to provide a basis for the preliminary design and, in the case of Green River, the basis for moving the pile. Such preliminary flood estimates do not have to be elaborate or detailed and can usually be estimated using very simple rodels (e.g. SCS triangular unit hydrograph and normal velocities) or using published estimates of large floods (e.g. Crippen and Bue).
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- 3. In general, we consider it inappropriate to halt' the search for alternate sites after only one other site is identified. For Green Rivar, no other sites were . identified after the SOS option was concluded to-be feasible.
It appears that, in this case, the SOS option may not be as good as previously thought,.and other sites may-need to be identified to meet the overall purpose of the CADSAR. Regardless of the feasibility of SOS, additional alternatives should have been provided in the CADSAR, along with preliminary design data, cost data, site data, and further recommendations for detailed site investigations.
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