ML20247L548
| ML20247L548 | |
| Person / Time | |
|---|---|
| Issue date: | 03/28/1989 |
| From: | Johnson T NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Lohaus P NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| REF-WM-3 NUDOCS 8904050486 | |
| Download: ML20247L548 (2) | |
Text
.
4 MAR 21 1999 MEMORANDUM FOR:
Paul Lohaus, Chief Operations Branch Division of Low Level Waste Management and Decommissioning, HMSS FROM:
T. L. Johnson, Sr. Hydraulic Engineer Operations Branch Division of Low Level Waste Management and Decommissioning, NMSS
SUBJECT:
MEETING WITH DARREL TEMPLE REGARDING HYDRAULIC DESIGN CRITERIA On February 27, 1989, I met with Darrel Temple, Research Hydraulic Engineer with the Agricultural Research Service (ARS), Stillwater, Oklahoma. The meeting was held in ipy office in Rockville, Maryland. The purpose of the meeting was to discuss various aspects of a recently-published ARS design manual entitled " Stability Design of Grass-Lined Open Channels". This manual is currently being used by the NRC staff in the development of regulatory guidance and forms the basis for the selection of many design parameters related to the design of unprotected soil covers at uranium mill ' J11ngs sites in the western United States.
During the meeting, I sought out Mr. Temple's opinion on various design parameters discussed in the manual and solicited his opinions regarding the applicability of the manual as a tool for designing soil covers for the protection for uranium mill tailings sites. The major conclusions reached in our discussions are summarized below.
1.
The values for soil shear stress res tance provided in the ARS design manual are generally acceptable for granu.tr soils with little or no cohesion.
2.
The values for soil stress resistance and procedures for modifying them, as mvided in the ARS design manual, are probably not adequate to reflect long o.m changes which would occur to cohesive soils over a period of 200-1000 years.
In general, it is felt that changes could occur to the soil characteristics as a result of normal weathering and random processes. Such changes could significantly affect the plasticity and the resulting credit to be given for cohesion. To be reasons'oly conservative, no additional credit, above the base level of shear stress resistance, should be given.
3.
The design procedures discussed in the manual are intended to apply to
/
i well-maintained grassed channels, located in areas where a dense sod-forming or j
turf-forming grass can be developed. Because no maintenance is permitted in 1
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assur'ing the design life of the cover for a' period of. 2001000 years, relatively conservative measures are needed to evaluate the effects of various phenomena such as flow concentration, design flow rate, Manning's 'n' value, J
etc.
l 4.
Only in rare cases can credit be given for the ' vegetation which'is generally prevalent in most areas of the western United States where most tailings sites-are located.
It is felt that in order for vegetation to be effective, a stem i
density of 200 300 stems per square foot is necessary. Such~ densities'are
'l generally not present at most tailings sites. Additionally, it is felt that f
typical western vegetation could actually be detrimental by increasing 6
roughness and flow concentrations.
j l
ORIGINAL SIGNED BY j
k T. L. Johnson, Sr.. Hydraulic Engineer Division of Low Level Waste Management-1 and Decommissioning, NMSS
.j i
1 Distribution:
CentraliFile T %5013 %
{
RBangart, R IV JGreeves, LLWM MBell, LLRB JSurmeier, LLTB PLohaus, LLOB MFlie9el, LLOB TLJohnson, LLOB JJones, LLOB rf NMSS rf PDR YES g/
PDR NO
/ / Category: Proprietary / /
or CF Only / /
ACNW YES g/
NO / /
SUBJECT ABSTRACT: Meeting on hydraulic design criteria s sN OFC :LLOB
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- LLOB
- LLWM
- LLWM
- hM55
- NM55
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