ML11214A194
| ML11214A194 | |
| Person / Time | |
|---|---|
| Site: | West Valley Demonstration Project, P00M-032 |
| Issue date: | 08/02/2011 |
| From: | West Valley Environmental Services |
| To: | NRC/FSME |
| References | |
| Download: ML11214A194 (18) | |
Text
Mitigation of the Contaminated Groundwater Plume at the West Valley Demonstration Project, New York, USA - 10409 West Valley Environmental Services LLC 10409: Mitigation of Groundwater Contamination at the WVDP 20447_1
Project Partners 10409: Mitigation of Groundwater Contamination at the WVDP 20447_2
West Valley Demonstration Project (WVDP)
- U.S. Department of Energy (DOE) project
- ~3535 miles south of Buffalo Buffalo, NY
- New York State Energy Research and Development Authority (NYSERDA) holds title to the 3,345 acre site
- Site of nations only commercial spent fuel reprocessing facility to ever operate
- Operated 1966-1972
- Processed 640 tons of fuel
- Generated ~ 600,000 gallons of Location of the West Valley Site high-level liquid waste containing
>30 million curies in 1980
- DOE assumed control of approximately 200 acres of the site in 1982 to conduct the WVDP [per WVDP Act (Public Law 93 368)]
93-368)]
10409: Mitigation of Groundwater Contamination at the WVDP 20447_3
WVDP Site The WVDP premises (reprocessing plant and N associated facilities) is located in an area of rolling hills that mark the southern extent of the most recent glacial advance.
The site is a small plateau, within a glacial valley, bordered by stream channels on the north andd eastt and d ascendingdi hill slopes on the south and west. WVDP premises marked by white line 10409: Mitigation of Groundwater Contamination at the WVDP 20447_4
WVDP Site On the northern portion of the site 10 - 30 feet f t off relatively l ti l N permeable material occurs above a confining (low permeability) clay layer layer.
Precipitation that infiltrates in this area moves downward to the clay l
layer and d th then ddowngradient di t tto th the northeast.
The groundwater surfaces at the edge of the plateau as seeps or springs.
West Valley Demonstration Project 10409: Mitigation of Groundwater Contamination at the WVDP 20447_5
Background - Groundwater Plume In late 1993, contaminated groundwater surfaced in g
ditches on the North Plateau.
Geoprobe investigation conducted summer 1994 to determine nature and WVDP extent of contamination.
Contaminant involved is Strontium-90 (Sr-90) and has been attributed to a Ditches process line leak during reprocessing in the 1970s.
Area of leading edge of Sr-90 plume 10409: Mitigation of Groundwater Contamination at the WVDP 20447_6
Background - Groundwater Plume 1994 characterization identified western lobe of plume which had surfaced in North Plateau ditches.
Pump and treat system installed in the fall of 1995 to mitigate surfacing and off-site movement of contaminated groundwater.
- ThThree wells, ll approximately i t l 10 between wells Since 1995, 2-4 million gallons of groundwater have been collected and treated annually through the sites radioactive wastewater system.
t pumping wells location 10409: Mitigation of Groundwater Contamination at the WVDP 20447_7
Background - Groundwater Plume 1996-1998 Upgradient drainage improvements made to reduce surface water recharge of the plume.
Conducted C d t d additional dditi lGGeoprobe b characterization work both near the leading edge and in the source Parking lot (upgradient) drainage collection system area of the plume plume.
Decision to install pilot Permeable Treatment Wall (PTW) on eastern lobe of the plume.
1997 diagram on leading area of the plume 10409: Mitigation of Groundwater Contamination at the WVDP 20447_8
Background - Groundwater Plume 1999 Pilot PTW installed on eastern lobe
- 30 long by 26 deep by 7 wide
- Sheet piles driven, dewatered, excavated, zeolite placed, piles removed 2002 Comprehensive assessment of the pilot PTW function completed
- Zeolite removed Sr-90
- Flow through wall restricted possibly due to...
- Clay smearing by sheet piles
- Z lit fining Zeolite fi i Pilot PTW installation 10409: Mitigation of Groundwater Contamination at the WVDP 20447_9
2007 Survey of Potential Mitigation Technologies 2007 Plume 2007 Surveyed technologies to mitigate plume leading edge expansion.
Technologies Screened
- Physical Barriers
- Hydraulic Barriers
- In-Situ Fixation/Stabilization
- Monitored Natural Attenuation (MNA)/Enhanced Attenuation (EA)
Development of Remedial Action Alternatives
- 8 Alternatives Developed which included the No Further Action Alternative - Maintaining the Current Approach 10409: Mitigation of Groundwater Contamination at the WVDP 20447_10
Alternatives Evaluated
- Alternative 1: Maintain Current Approach
- Alternative 2: Interceptor Trench Drain
- Alternative 3: Groundwater G Extraction Wells
- Alternative 4: Far Downgradient Interceptor Trench Drain
- Alternative 5: Far Downgradient Groundwater Extraction Wells
- Alternative 6: In situ Plume Treatment with Passive Permeable Treatment Wall
- Alternative 6A: In situ Plume Treatment with Active Permeable Treatment Wall
- Alternative 7: Far Downgradient In situ Plume Treatment with Passive Permeable Treatment Wall Area of leading edge of Sr-90 plume 10409: Mitigation of Groundwater Contamination at the WVDP 20447_11
Alternative 6 Selected for Evaluation In-situ Plume Treatment With Passive Permeable Treatment Wall.
Note: 2007 concept for PTW l
location/dimensions ti /di i was based on available field data Alternative 6 - PTW concept 10409: Mitigation of Groundwater Contamination at the WVDP 20447_12
Characterization of Plume Leading Edge 2008-09 Placed more than 80 borings and microwells.
- Characterized geology, hydrogeology, hydrogeology geochemistry in the area of the proposed PTW ((10,000
, pCi/L p
area)
- Refined understanding of Sr-90 Sr 90 distribution to the northern edge of the March 2009 understanding of plume configuration plateau 10409: Mitigation of Groundwater Contamination at the WVDP 20447_13
Hydrogeoligic Cross-section Along PTW Alignment 10409: Mitigation of Groundwater Contamination at the WVDP 20447_14
Laboratory Testing of Zeolites Two natural zeolites high in clinoptilolite content are being tested.
- Grain size analysis
- Permeability mineral composition
- Cation C ti exchange h capacity it
- West Valley strontium specific removal (column tests)
- Non-radioactive columns using simulated groundwater; Sr-88 surrogate for SR-90, 5 key cations
- Radioactive columns using actual North Plateau groundwater (~50,000 pCi/L)
Non-radioactive column tests 10409: Mitigation of Groundwater Contamination at the WVDP 20447_15
PTW Design PTW Dimensions
~ 850 feet long
~ 3 feet wide 20 - 25 feet deep Note: above based on 30% design 10409: Mitigation of Groundwater Contamination at the WVDP 20447_16
PTW Installation PTW installation is planned to be done with a continuous, one-pass trencher that cuts a trench and fills with media (zeolite) in one operation.
ti
- Installation of PTW without use of support piles or in-trench slurry avoids possible impacts to permeability at soil-zeolite interface Trencher equipped with 25 bar, 2 wide cutter 10409: Mitigation of Groundwater Contamination at the WVDP 20447_17
Path Forward
- Spring p g 2010 - complete p final design g
- Spring/summer 2010 - purchase zeolite, place contract for installation
- Fall 2010 - install PTW 10409: Mitigation of Groundwater Contamination at the WVDP 20447_18