ML20044B602
| ML20044B602 | |
| Person / Time | |
|---|---|
| Issue date: | 01/28/1993 |
| From: | Haque M NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Gillen D NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| REF-WM-48, REF-WM-63 NUDOCS 9302030227 | |
| Download: ML20044B602 (4) | |
Text
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JAN 2 - 1993 MEMORANDUM FOR:
Den Gillen, Section Leader Remedial Action Section LLUR/LLWM/NMSS FROM:
Mohammad Haque, Project Manager Remedial Action section LLUR/LLWM/NMSS
SUBJECT:
DURANGO, CO, AND MEXICAN HAT, UT, SITE VISITS On November 4 and 5, 1992, the Nuclear Regulatory Commission staff visited the Durango, Colorado, and Mexican Hat, Utah, sites. The purpose of the Durango site visit was to observe the displacement of riprap and erosion downstream of the outlet of Ditch No. 2.
This situation had been observed-during DOE's prelicensing inspections of the site, and was looked at by the NRC staff to assess any generic impacts to the erosion protection technical guidance. The Mexican Hat site was visited to discuss and resolve the issues on erosion' protection design that remain open from the staff's review of the preliminary final Remedial Action Plan.
Enclosed for your information are the subject trip reports.
gpWAffGNED ?Y Mohammad Haque, Project Manager Remedial Action Section LLUR/LLWM/NMSS
Enclosures:
As stated cc:
S. Hamp, DOE, Alb R. Edge, DOE, Alb D. Willis, CDH DISTRIBUTION: Central File NMSS r/f RBangart WBrach JAustin JSurmeier PLohaus DRom LJCallan,RIV RHall,URF0 LLWM r/f SUBJECT ABSTRACT: Durango, CO, and Mexican Hat, UT, Trip Reports In smal1 Box on "0FC:" Iine place a: C = Cover E = Cover L Enclosure N = No Copy 0FC :
LLUR E
LLUR LLUR 45' LLWM LLWM NAME: Wiique/iuir [ TJobs^od AMullins M DATE:
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/ /93 Path & File Name:S:LLWTYPE\\EDIE\\ HAT-TRIP.MWH OFFICIAL RECORD COPY In small Box on "DATE:" line place a: N = E-Na11 D1str1bution Copy H = Hard Copy PDR :
YES X NO Category:
Proprietary or CF Only ACNW:
YES NO X Delete file after distribution Yes No IG:
YES.
NO X 9302030227 930128 PDR WASTE WM-48 PM -
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1 TRIP REPORT FOR SITE VISIT / MEETING AT DURANGO. CO. UMTRA PROJECT SITE Ralt:
November 4, 1992 Pig _1:
Durango, Colorado Purcose:
To observe displacement of riprap and erosion downstream of the outlet of Ditch No. 2 Attendees:
Department of Eneroy Russel Edge Jacobs Enaineerina Groun (Technical Assistance Contractor)
Ed Artiglia Gerald Lindsey State of Colorado Deoartment of Health Dennis D. Willis Nuclear Reaulatory Commission Mohammad Haque Ted Johnson Allan Mullins Discussion:
the Nuclear Regulatory Commission staff arrived at the Durango, Colorado, UMTRA Project site at 2:00 p.m. on November 4, 1992, to observe the displacement of riprap and erosion downstream of the outlet of Ditch No. 2.
This situation had been observed during the Department of Energy's (00E) prelicensing inspections of the site, and was looked at by the NRC staff to assess any generic impacts to the erosion protection technical guidance. The NRC staff, accompanied by DOE and the State of Colorado Department of Health (CDH) staff, walked the entire site, including the channel outfall areas and observed displacement of riprap and erosion downstream of outfall. ditches.
The outfall areas have experienced some erosion and displacement of riprap near the outlets. There were three locations of erosion and flow concentration at the downstream end of the rock-protected area where flow discharges into a natural gully. This area of rock protection was added by DOE as an additional precaution and is not actually part of the erosion protection design of the site. The displacement of the rock appeared to be the result of erosion and sloughing of the underlying stoep soil slope as flow is discharged to the natural gully. We were told that this erosion is more than several hundred feet from the tailings and that there is no immediate danger of eroding tailings, since the actual site erosion design is functioning properly.
Several other areas of erosion and deposition were observed in the swales and-discharge channels and in other areas of the site. There appeared to be no significant problem with this erosion and deposition.
The erosion and possible resolution of the problem was discussed with DOE and CDH. No resolution was reached, nor were any commitments made. DOE will address these issues in their Annual Prelicensing Inspection Report for the Durango site.
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TRIP REPORT FOR SITE VISIT / MEETING AT MEXICAN HAT. UT. UMTRA PROJECT SITE
)
QAlg:
November 5, 1992 Place:
Mexican Hat, Utah Purcose:
To discuss and resolve issues on erosion protection design with DOE and their contractors.
Attendees:
Deoartment of Enerav l
Russel Edge Jacobs Engineering group (Technical Assistance Contractor)
John McBee.
Gerald Lindsey Morrison-Knudsen ES (Remedial Action Contractor)
Chris Weston Robert Claire Robert D'Areeo
~
P.K. Chen Tim Swisse Ralph Dow-Nuclear Reaulatory Commission Mohammad Haque Ted Johnson Allan Mullins Discussion:
2 The Nuclear Regulatory Commission staff arrived at the Mexican Hat, Utah..
UMTRA Project site at 8:00 a.m. on November 5, 1992. After a briefing on i
radiological safety, we toured the site. We observed various ditches, gully areas, apron areas, gully headcutting, and other portions of the entire site.
During this time, we discussed the various open issues with the Department of 1
Energy (DOE) and their contractors' personnel.
SURFACE WATER HYDROLOGY:
NRC staff walked the entire perimeter of the site, observing gullies and locations of proposed erosion protection.
Particular attention was devoted to the west ditch, north ditch, Gully #1,-apron areas, and toe areas. We discussed several open issues with DOE and possible resolution of these issues during the walking tour.
During the afternoon, we visited a proposed rock source for Type C rock, located near Alhambra Rock.
Following the observations of the site, we held a meeting with D0E.
Issues ilscussed included the following:
1.
Criteria for defining competent rock; 2.
Criteria for non-erodibility, especially for areas with weak underlying layers; 3.
Further design and specification changes needed; 4.
Information needed for adequate documentation of rock acceptability; 5.
Problems with details of draft hydraulic design; and 6.
Further actions and activities needed.
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Significant progress was made during the discussions in each of the above areas to identify possible methods of resolution for DOE to investigate in their upcoming revisions.
GEOLOGY:
The NRC staff observed the first few trenches of a series being cut with a backhoe in the gully heads at the Mexican Hat disposal site. DOE has been requested to identify the extent of competent rock layers which will resist i
erosion and prevent rapid headcutting of gullies in the vicinity of the tailings disposal pile.
Several hard limestone layers of 1 to 2 feet in thickness were observed in each of the opened trenches. These layers were separated by 6 to 8 feet of erodible shale and siltstone.
The heads of these
{
gullies will be covered by riprap to protect the more erodible zones between the resistant layers. The combination of in-place resistant layers and riprap will provide long-term protection against headward erosion of the gullies 1
toward the tailings. The lateral extent of the layers will be identified, and their competency will be assessed using augers. Failure to penetrate will be a measure of hardness. Further evaluation will be done when DOE has completed the trenching and gathered information on the lateral and vertical extent of the resistant rock layers.
The staff observed a potential source of riprap several miles away from the disposal site southwest of Alhambra Rock. A several-hundred-acre area capped by a limestone bed is to be drilled and tested. The bed is exposed in outcrop where it is 6 to 8 feet in thickness.
Plans are to take about 20 cores of the rock for testing.
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