ML20206E254

Forwards Comments on Proposed Reclamation Plan for Ray Point Tailings Impoundment.Addl Info & Analyses Re Surface Water Hydrology Needed

ML20206E254
Person / Time
Issue date:	06/03/1986
From:	Hawkins E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
To:	Bailey E TEXAS, STATE OF
References
REF-WM-39 NUDOCS 8606230238
Download: ML20206E254 (3)

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DISTRIBUTION Docket File WM-183 PDR/DCS S

SIS 43/WM-183/PJG/86/05/30/0 hangart,RIV PGarcia LLW Branch, WMLU JUN 0 31986 URF0 r/f URF0:PJG SIS 43 040WM183101E Mr. Edgar D. Bailey, Director Division of Licensing, Registration and Standards Texas Bureau of Health i Bureau of Radiation Control 3 1100 West 49th Street Austin, Texas 78756

Dear Mr. Bailey:

We have reviewed the responses to previous TDH/NRC~ comments submitted by ^!

Exxon Minerals Company with regard to the proposed reclamation plan for the Ray Point tailings impoundment. This information was transmitted to us by your letter dated March 28, 1986.

Our review indicates that additional information and analyses regarding ,

> surface water hydrology aspects of the proposed reclamation plan will be necessary before we can conclude that the plan meets the EPA 40 CFR 192 standards. The specific information and analyses required are discussed in the enclosure to this letter.

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In addition, our review of the alternative cost evaluation provided by Exxon leads us to conclude that sericos consideration should be given to flattening embankment outslopes from 5H:1V to 10H:1V. The information provided by Exxon shows the cost differential for the two alternatives to be approximately $138,000. In light of the extreme uncertainty involved in quantitatively evaluating the long-term stability of reclaimed slopes, we feel a significant degree of additional assurance regarding the stability of the slopes can be provided at a relatively small incremental cost.

We would be happy to provide assistance in your review of Exxon's response to the request for information and discuss the issue of embankment outslopes with you at your convenience. Should you have any -

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SIS 43/WM-183/PJG/86/05/30/0 JUN 0 3 566 questions, please do not hesitate to contact Pete Garcia or me at (303) 236-2805.

Sincerely, orMir-1 (!m-: P ru . -a r. tv-2;. .

Edward F. Hawkins, Chief Licensing Branch 2 Uranium Recovery Field Office Region IV

Enclosure:

As stated

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ENCLOSURE NRC Comment on Proposed Reclamation Plan for the Ray Point Project The information presented with regard to surface water hydrology aspects of the proposed plan is not adequate to allow us to conclude that the plan has been designed using state-of-the-art methodology. It appears that the reference " Design of Small Dams" was used to obtain PMP values, which were then used to determine PMF flows and the resulting velocities.

This reference is outdated and has been superceded by hydrometeorological reports prepared by NOAA. The hydrologic analyses should be repeated using PMP values for a local storm event from the appropriate NOAA report. Second, it is not clear how rainfall values were broken down into the 12-minute segments shown on the Sediment II output provided in Appendix F. Incremental rainfall values should be determined as specified in the appropriate NOAA report. Third, it is not clear what' ' '~

assumptions and calculational procedures were utilized to determine peak ~

flow rates and velocities. Specifically, information required includes methods and assumptions used in converting rainfall values to runoff values and times of concentration for each watershed.

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