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

9

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

10

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

11

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

12

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