ML20215M525
| ML20215M525 | |
| Person / Time | |
|---|---|
| Issue date: | 10/21/1986 |
| From: | William Ford NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Martin D NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| REF-WM-39 NUDOCS 8610300362 | |
| Download: ML20215M525 (5) | |
Text
DISTRIBUTION SEsfA(ISO 9)3 MHaisfield 4
WMGT rf JGreeves 10iSS rf SSmykowski RBrowning JKane L'llI/0C/10/3 MEell MKnapp JBunting JStamer PSJustus MWeber s
I 1 1986 WFord & rf DGoode MPliegel MYoung MEMORANDUM FOR:
Dan Martin, Section Leader PDR LDeering URPS DGillan..
JForstrom GGnugnoli FROM:
William Ford, Geohydrologist WMGT
SUBJECT:
MEETING
SUMMARY
ON HYDROLOGIC TESTING 0F LINERS AND COVERS AT UMTRAP SITES On September 22, 1986, a meeting was held to discuss the type of geohydrologic liner and cover testing procedures for use at UMTRAP sites.
There is a need for this type of testing when the Remedial Action Plan takes credit for liner or cover performance in estimating hydrologic effects.
There will also be a need for this type of testing at Low Level Waste disposal sites.
In this meeting it became apparent that the technical staff is not in agreement on how covers and liners should be tested.
Therefore, it was agreed that until this issue is resolved, laboratory tests should continue to be used to test covers and liners at UMTRAP sites and it is recommended that a study be conducted in a phased approach.
This approach would have the advantage of committing resources gradually, since each phase would only be implemented if it is agreed that the previous phase indicated the need.
The attached enclosure contains additional details of the meeting and recommendations.
Should you have any questions please don't hesitate to contact u.e (74697).
A William Ford, Geohydrologist WMGT Enclosure As Stated WM Record File WM Project _ d[
Docket No.--
PDR #
LPDR Distribution:
8610300362 861021 PDR WASTE
l-WM-39 PDR (Return to WM,623-SS)
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- MFliegel DATE :86/10/1o
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WM39/WHF/86/9/22 >
MEETING
SUMMARY
ON HYDROLOGIC TESTING OF LINERS AND COVERS On September 22, 1986, a meeting was held to discuss the type of testing procedures that are appropriate to determine the hydrologic properties of liners and covers at UMTRAP sites. The need for this type of testing occurs when Remedial Action Plans take credit for a liner or cover in estimating hydrologic impacts. The need to conduct these types of tests is of immediate concern at UMTRAP sites and will be a future concern at low level waste disposal sites. At this meeting it became apparent that the technical staff is not in agreement on how covers and liners should be tested. Therefore the following recommendations were suggested to resolve the issue.
RECOMMENDATIONS 1.
Until the NRC staff has formulated a technical position on the type of cover and liner tests, at UMTRAP sites, laboratory tests i
correlated with standard ergineering parameters (Procter Density and l
moisture per cent) will continue to be used. The engineering parameters will then be sampled in the field during construction.
This is considered to be currently acceptable engineering practice.
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l 2.
The cover and-liner testing procedure recommended by the NRC should i
be conducted in a manner that does not unduly compromise the construction of the liner or cover.
In addition, testing procedures are preferable if they can be implemented before or during i
construction rather than after the liner or cover has been constructed.
I 3.
It is recommended that a study of appropriate cover and liner testing methods be done in two or three phases:
(a) Phase One should describe the benefits and limitations asraciated with using laboratory tests versus field tests for liners and covers. This phase would be accomplished by i
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reviewing available literature and contacting other government agencies and experts. This phase would produce a report that describes when one technique is superior to another.
(b) If it is agreed that Phase One indicates that field tests should be considered as an alternative to laboratory i
O WM39/WHF/86/9/22 testing, Phase Two would be implemented.
Phase Two would evaluate the practicality of using field tests of covers and liners. Again this phase would be accomplished by reviewing available literature and contacting other government agencies and experts. This phase would produce a technical position that describes the testing methods and approaches that are acceptable to the staff for determining hydrologic properties of covers and liners.
(c) If it is concluded in Phase Two that satisfactory results cannot be produced without the collection of experimental data, a brief report will be prepared that describes the type of experimental data that is needed. As part of this phase, experimental data being collected by other agencies will also be described and a discussion will be included of whether this data will meet NRC needs. With the completion this report the agency will then have the option of deciding if it wishes to implement the collection of experimental data or if other options should be developed.
DETAILED DISCUSSION OF MEETING A meeting to discuss the type of methods that should be used to test liners and covers for hydrologic properties was held on September 22, 1986. This meeting was attended by representatives from WMLU, WMPC, WMEG, and WMGT. Technical attendees were William Ford, (WMGT), Jonathan Forstrom, (WMGT), Daniel Goode, (WMGT), Joesph Kane, (WMEG), Steve Smykowski, (WMEG), Mike Weber, (WMGT), and Mike Young, (WMGT). The need for this meeting arose during reviews of UMTRAP sites.
Some of these designs took credit in their ground water quality impact projections for favorable hydrologic characteristics of liners and covers, yet did not provide for in situ testing and verification of these characteristics.
If credit for geohydrologic properties of a cover or liners is taken then specific hydrologic parameters have to be inspected before, during, or after construction to confirm that the site has been reclaimed according to the Remedial Action Plan. A similar problem exists at low Level Waste Disposal Sites when natural covers and liners are used.
Participants in this meeting discussed several alternative testing methods.
These methods can be summarized as follows:
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1.
Laboratory Testing:
Samples of proposed cover material are sent to laboratories, where the particle size is measured.
The samples are l
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O WM39/WHF/86/9/22,
then prepared for a range of moisture content and densities and the saturated hydrologic permeabilities measured.
From these tests an appropriate cover material, compacted to a specific density and containing a specific moisture percent, is selected as appropriate cover material. Thereafter, during construction of the cover or liner, only grain size, moisture percent, and density measurements are made to confirm that the cover or liner is built properly.
2.
Test Plots:
In this method, a test pit is constructed from the proposed liner or cover material to simulate construction of the full-scale cover or liner. The test pit is built to the proposed density and moisture percent or a range of values.
Field tests such the use of double ring infiltrometers are used to determine permeability values for the test pit. The permeability values are then correlated to specific particle size, moisture percent, and density measurements. Just as in the laboratory testing method, these parameters are then monitored during construction to ensure that the liner is constructed properly.
3.
Post Construction Tests: A third alternative discussed, was to conduct field tests of the liner or cover to determine if it had been constructed properly. This alternative has the disadvantage of not being to correct the design prior to or during construction, when it is easier and less costly to make corrections, but has the advantage of confirming construction values after the liner or cover is in pl acc~.
4.
Other:
Further discussion, included combinations of the above three methods.
As a result of these discussions several areas of technical disagreement were identified. One area of disagreement revolved around the idea that field tests provide more reliable estimation of hydraulic properties than laboratory tests.
Some individuals cited professional articles that indicated field tests appear to be more accurate than laboratory tests in determining field scale hydraulic l
l conductivities. Their knowledge of the techrical literature indicated that laboratory tests produce values of saturated permeabilities that are loggr by several orders of magnitude than field-scale values. However, some individuals were not convinced of this and cited publications they felt indicated field tests were still in preliminary stages of development and would be difficult to implement.
Phase One of the proposed study cescribed in the summary section should attempt to answer these issues.
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WM39/WHF/86/9/22
_4 Another question arose concerning the correlation of field tests with engineering parameters. Technical literature was cited that indicated field tests could be correlated with engineerir.; parameters. However, no one was able to describe how this had been done and should be done. This question
- hould be reiolved by Phase Two of the proposed study.
Another ques: ion was raised over the economics (money and time) of correlating field tests with engineering parameters or of collecting field data after a cover has been built. Again this question should be resolved by Phase Two of the proposed study.
SUMMARY
Although the meeting did not resolve the issue of field testing, it did highlight the difference of opinion on this issue. These differences appear to be due to the information that was available to each of the staff.
It was therefore agreed that those individuals with differing opinions would trade copies of the publications from which they developed their opinions (this has been completed).
Further, the problem should be studied in phases, (see recommendations) with Phase One being an evaluation of the reliability of field and laboratory testing.
Phase Two would be implemented if Phase One indicated the need to consider the feasibility of the field techniques in more detail.
phase Three would describe the need for the collection of more data and would only be implemented if Phase Two could not accomplish its purpose.
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