ML20033H121
| ML20033H121 | |
| Person / Time | |
|---|---|
| Issue date: | 04/09/1990 |
| From: | Surmeier J NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Lohaus P NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| REF-WM-68 NUDOCS 9004180234 | |
| Download: ML20033H121 (2) | |
Text
-. _ _ _ _ _ _
i r,
i
-i APR - 9 M MEMORANDUM FOR:
Paul H. Lohaus, Chief Operations Branch Division of Low-Level Waste Management and Decommissioning, NMSS FROM:
. John J. Surmeier, Chief Technical Branch Division of Low-Level Waste Management.
and Decommissioning, NMSS
SUBJECT:
PACIFIC NORTHWEST LABORATORIEG (PNL) LETTER ON UMTRA COVER DESIGN Comments attached to the February 20, 1990 letter from J. D. Smyth of PNL suggest that assumptions supporting the NRC staff groundwater travel time estimate through the Green River site cover -
and tailings (Green River Site Technical Evaluation Report) are not conservative.
Mr. Smyth's conclusion is based.ons.
(1) studies indicating that laboratory hydraulic conductivity measurements of cover and liner systems may be as much as three orders of magnitude less than hydraulic conductivities measured-in the
- field, (information in a note to Bill Ford, WMGT, 24 Sept., 1986) ; and (2) numerical simulations conducted at PNL showing that covers experience saturated flow conditions after relatively chort periods of time.
l Today, both laboratory testing of undisturbed and remolded soils, and in-place measurements (e.g., infiltrometers or lysimeter pans) are used to establish vertical hydraulic conductivities of soils placed in cover and liner systems.
Several studies cited in the 9/24/86 note to Bill Ford, indicated that because of the small size of laboratory samples with respect to field scale, laboratory tests tend to under estimate field scale hydraulic conductivity.
It is now generally recognized that the results of. carefully performed laboratory tests on-" homogeneous" materials are comparable to in-place measurements (EPA Seminar Publication,
" Requirements for Hazardous Waste Landfill Design, Construction, and Closure",- August 1989).
In addition, to assure adequate representation of as-built Green River site cover, 14 evenly distributed cover samples were collected and tested.
+
l Although PNL's numerical simulations of cover performance indicate.
that it may be more realistic than conservative to assume cover saturation, the assumed cover saturated hydraulic conductivity (2.0-E8 cm/s) in the Green River site TER groundwater travel time' 9004180234 900409 PDR WASTE WM-68
- PDC,
(/hlh 'i
7 A:\\FR-LOHOUS.MEM estimate is more than three times actual mean cover hydraulic conductivity measured in the laboratory (6.1E-9 cm/s).
- Finally, groundwater travel time is a measure of flow through the cover and tailings, and as a measure of transport, does not take credit for chemical retardation, and contaminant dispersion and dilution of hazardous constituents.
LLTB staff continues to support the conclusion in the Green River
-TER that the cover designed and built by DOE meets the EPA 40 CFR 192 groundwater protection standard.
(S:GlLO) 10!!N J. SU!EBER, John J.
Surmeier, Chief Technical Branch Division of Low-Level Waste Management and Decommissioning, NMSS Distribution: % Centra 1XFile]JXWM6,83 LLTB r/f NMSS r/f
~noss JStarmer RBoyle PLohaus JSurmeier F
JGreeves
~RBangart PDR Yes:
X PDR No:
Reason:
Proprietary or CF Only ACNW Yes:
K No:
SUBJECT ABSTRACT:
SEE SUBJECT OF MEMORANDUM
- LLTBh__
LLT g {=
OFC :LLTB
- LLTB
- LLT
=
========== y=====:JStarmer
== _
=
NAME:FRoss/lj
- JKane
- MTokar
- J urmeier
=====================================================
Y /4 /90
- 4 / 3 /90
/
/90
- P/ 7/90 : y//f/90 DATE:
OFFICIAL RECORD COPY
,