1 overview of the epri groundwater assessment program presented at: rets-remp workshop, june 26-28,...
TRANSCRIPT
1
Overview of the EPRI Groundwater Assessment
Program
Presented at: RETS-REMP Workshop, June 26-28, 2006Mashantucket, CT
Eric L. Darois, M.S., CHPDave Scott, M.S., CPG, LEP
EPRI Consultants (RSCS, Inc.)
Sean BushartEPRI
Ron Cardarelli, M.S.CN Associates, Inc.
2
Program Objectives and Scope
• Phase 1:– Perform a site-specific assessment of Groundwater
Contamination Risks.– Bring Lessons-Learned to each site from Prior Groundwater
Investigations.– 2 to 4 Days, 2 Professionals
• Health Physics/REMP• Geologist/Hydrogeologist
– Prepare site-specific report with recommendations based on assessment
• Phase 2: – Develop Industry Guideline on Groundwater Protection
• Phase 3: – Advanced Nuclear Project – Groundwater Protection Lessons
Learned in development of new nuclear plants
3
RETS/REMP 2005 Discussion• Ground Water Monitoring Guidance for Nuclear Power
Plants (EPRI Report No. 1011730)
– 150-page EPRI Report• Two Decommissioning Sites• One Operating Site
– Historical Review– Requirements– Potential Source Locations– Investigation Methods and Tools– Determining Occurrence, Nature, Extent– Sampling Considerations– Data Analysis and Interpretations
• Recommended GW Monitoring as Part of REMP
4
Assessments/Experience Performed and Gained
• Yankee Rowe (Decommissioning)• Connecticut Yankee (Decommissioning)• TMI EPRI Assessment• Braidwood Assistance• Indian Point Assistance
5
Observations & Recommendations
• Define Program Objectives– Radionuclides, MDCs, and
“Positive” Results– Sampling Regime– Sampling Methods– Data Assessments– Sampling Methods and Field
Parameters• Consider Preventative
Maintenance Programs for Wells• Consider Soil Sampling for H-3
Sources
6
Observations & Recommendations (Con’t)
• Investigation Complexity Results in Wide Variation in Duration– Sand-Laden Aquifer– Fractured Bedrock – Deep Bedrock– Barriers to GW Flow
7
Observations & Recommendations (Con’t)
• Tritium Saturated Concrete• Documentation of Spills and Leaks
– Soil Contamination Events– Secondary Water– Tank Leaks– SFP “Minor” Leaks
• Resource Needs not Recognized • Data Management
8
Observations & Recommendations (Con’t)
• Data Management– Electronic Data vs Paper– What Radionuclides?– MDAs ?
• Required vs Achieved
– Sample Event Planning– Sample Control– Data Control– Data Assessment
• Statistical Analysis
• Trend Analysis
-10
-5
0
5
10
15
0 10 20 30 40 50 60
Rank Order
Co
nc
en
trati
on
(p
Ci/
L)
Co-60Lim. Mean-2-Sig.+2-Sig.Ave. MDC
0
5
10
15
20
25
30
-4.98 -3.64 -2.29 -0.95 0.40 1.74 3.09 4.44 5.78
Concentration (pCi/L)
Fre
qu
en
cy
-4 -3 -2 -1 0 1 2 3 4
Standard Normal Quantile
Observed Distribution
Normal Distribution
Tritium in B-1 and CB-10
01000200030004000500060007000
Mar-97 Jul-98 Dec-99 Apr-01 Sep-02 Jan-04
Date
pC
i/L
CB-10 B-1 MDC
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Recognize the Iterative Process of GW Investigation
• Proceed with a phased approach that implements a “scientific method”
• Develop a Conceptual Site Model (CSM)
• Evaluate the existing site data (hydrogeology, source areas, contaminant distribution, transport mechanisms)
• Formulate a preliminary CSM (hypothesis) that explains the observed data
• Collect data: drill monitoring wells, sample and analyze GW, and conduct hydrogeologic testing
• Evaluate and interpret the resulting data
Evaluate
Results
Define
Data Gaps
Collect
Data
Develop/Revise
CSM
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Designing a GW Investigation
• Evaluate possible sources of contaminants• Evaluate possible radionuclides • Determine GW flow directions & mechanisms
– Install monitoring wells• Drilling methods
– Overburden wells– Bedrock wells– Screen Depths
– Measure GW levels– Sample and analyze GW
• determine concentrations
• Determine distribution
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Tools for the Investigation
• Water-level monitoring– Precipitation (primary input to GW)– Surface water (tidal interaction with
GW)– Ground water (flow direction and
gradient)• Water-level measurement techniques
– Electronic measuring tapes• Synoptic measurements in a set of
wells– Data-logging pressure transducers
• Continuous measurements in selected wells
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Elevation of Water Level in MW-102A (screened 33 to 38 feet in sand aquifer)
1115.5
1115.7
1115.9
1116.1
1116.3
1116.5
1116.7
1116.9
1117.1
1117.3
1117.5
7/20/200419:12
7/22/200414:24
7/24/20049:36
7/26/20044:48
7/28/20040:00
7/29/200419:12
7/31/200414:24
8/2/20049:36
8/4/20044:48
8/6/20040:00
8/7/200419:12
8/9/200414:24
8/11/20049:36
8/13/20044:48
8/15/20040:00
8/16/200419:12
Time
Wa
ter
Le
ve
l E
lev
ati
on
(fe
et,
MS
L)
Sample ground water at 45 to 53 feet in MW-109
Development of MW-109C, screened from 49 to 54 feet
Pressure grout 7 5/8" casing at 65 feet in MW-109
Advance 7 5/8" casing to 45 feet in MW-109
Example of GW Level Data Logging
13
More tools…
• Bedrock Borehole Logging• Tracer studies• Isotopic GW dating• Packer Testing
14
Ground Water Sampling
– Flow-through measurement cell to determine when samples are representative
• Temperature• pH• Turbidity• Dissolved oxygen• Specific conductance
– Water-level meter– Bailed Samples– Low Flow Sampling Methods
15
Observations/Guidance
• Potential Primary GW Sources (10 to 50 Million pCi/L):– Spent Fuel Pools– Refueling Water Storage Tanks– Sumps
• Secondary Sources– Secondary Water Spills and Leaks
• Possible Large Volume
• Primary Radionuclides of Concern Sr-90, Co-60, Cs-137, and H-3.– Tritium is the most mobile and pervasive.
16
Conclusions
• State Regulations May Require Additional Considerations• Engage Stakeholders Through All Phases• GW investigations are Iterative
– Maybe Years To Complete• Need a Conceptual Site Model• Additional Interest in
EPRI Assessments• Will Help to Implement
NEI Initiative