Managing Your Groundwater Program - Do’s and Don’ts Matthew Daly, P.G. 2007 RETS-REMP Philadelphia, PA

1. Managing Your Groundwater Program - Do’s and Don’tsMatthew Daly, P.G.2007 RETS-REMPPhiladelphia, PA

2. Groundwater Programs • Non-nuclear – thousands of sites over the past 30 years • Gas stations and bulk terminals • Dry cleaners • Manufacturing facilities • Landfills • Myriad of contaminants and site conditions • NAPLs, solvents, metals, PAHs…. • Sand, silt, clay, fractured bedrock, sediment and surface water • Well depths from 15 to 300+ feet • Sampling methods, frequency and parameters

3. Groundwater Programs – cont’d • Lessons learned can help to streamline and maximize effectiveness of groundwater programs at nuclear power plants • Planning with the end in mind – REMP

4. The Six Components of Effective Groundwater Monitoring Programs Assemble Project Team (1) Identify Sources, Receptors and Plant Influences (2) Calculate Tritium Flux Component (6) Groundwater Monitoring Program Develop & Refine Initial Conceptual Model (3) Implement Monitoring Program (5) Implement Phased Field Investigation (4)

5. Assemble Project Team Use Internal and External Resources

6. Identify Sources • Identify known or potential sources of liquid release to groundwater, e.g., Spent Fuel Pool, piping, sumps, tanks, spills, etc. • Tritium most common, but Cobalt-60, Cesium-137 and Strontium-90 also found. • Consider hierarchy of potential sources based on magnitude, age, duration, exposure potential to receptors and logistics of investigation.

7. Identify Sources – cont’d • Source Identification – Continue to evaluate throughout program to identify, control and eliminate where feasible. • Evaluation of Systems and Components • Evaluation of Procedures and Past Practices • Evaluation of Available Groundwater Monitoring Results

8. Identify Receptors • Groundwater Usage Survey • Springs • Surface water • On-site and off-site water supply wells • Receptor Analysis – Early in program to reinforce lack of risk posed and build stakeholder confidence

9. Sources & Receptors – Use Existing Data • FSAR & USAR geologic and hydrogeologic reports • Plant drawings and construction diagrams • 50.75(g) Files • Locate, inventory and sample existing wells • REMP program

10. Develop Conceptual Site Model

11. Refine Conceptual Site Model

12. Implement Phased Field Investigations • Design site assessment program to achieve project goal(s) • Characterize site geology and hydrogeology to the extent necessary • How do they affect contaminant distribution, migration and attenuation • Define contamination source, nature and extent • Don’t exacerbate site conditions – work from “outside-in, top-down”

13. Drilling Techniques

14. Drilling Technologies Rotosonic Telescope Casing Unit Cost / well Hollow Stem Auger Geoprobe Investigation Depth Degree of Conservatism

15. Overburden Investigation Tools Monitoring Wells Multilevel wells Cost Waterloo Profiler Soil borings Cone Penetrometer Qualitative Quantitative

16. Bedrock Investigation Tools Long open boreholes Pumping Tests Packer Tests FLUTe Rock coring Cost Multilevel wells Surface geophysics Air rotary Borehole geophysics Transducers Qualitative Quantitative

17. 30 20 10 0 -10 -20 0 2 4 6 8 10 Heterogeneity – Variability of Subsurface Aquifers 30 20 10 Elevation (ft) Elevation (ft) 0 -10 -20 -200 -100 0 100 200 23 24 25 26 27 28 29 100 200 300 400 500 600 4 5 6 7 0 2 4 6 8 Hydraulic Head Index of Hydraulic Conductivity Dissolved Oxygen Oxidation/ReductionPotential Specific Conductance pH (feet) (unitless) (mg/L) (mV) (uS/cm)

18. Data Representativeness

19. Aquifer Testing – Determine Groundwater Flow Rate • Hydraulic conductivity (K) • Field test to “stress” a well and monitor response in the groundwater level • Examples include slug, pumping and tracer tests • Need to consider scale effects

20. Aquifer Testing – Tools for Determining K Tracer Test Cost Pumping Test Slug Test Degree of Certainty in K value Volume of Aquifer Tested

21. Implement Monitoring Program • Select groundwater sampling method(s) • Select analytical parameters • Implement quality assurance/control program

22. Groundwater Sampling Methods • Various techniques • Bailer, thief, grab, diffusion bag, low-flow • Low yield wells need special attention • Low-flow considered most robust for obtaining representative groundwater samples (EPA, State and EPRI Draft Guidance)

23. Groundwater Sampling – Methods Low-flow 3-well volumes Cost Diffusion Bags Thief Grab Representativeness

24. Low-Flow Groundwater Sampling • Stabilization Parameters: • Temperature • Conductance • pH • Redox Potential • Dissolved Oxygen • Turbidity • Water Level

25. Selection of Analytical Parameters • Radiological • Tritium • Gamma • Hard to Detects? • Non-radiological? • VOCs (solvents) • PAH (fuels, oils)

26. Consider Monitoring Frequency

27. Implement QA/QC Program • Laboratory Quality Control Issues • Verify appropriate and consistent Lower Limits of Detection • Need to consider site-specific background levels • Need to consider State and Federal reporting levels • Reporting units (pCi/L versus mCi/ml) • Third party analysis of duplicate samples

28. Implement QA/QC Program – cont’d • Field Quality Control Methods • Duplicate/Blind Samples • Matrix Spike & Matrix Spike Duplicate • Equipment Blanks (Decontamination) • Performance Evaluation Samples

29. Tritium Flux Component • What is it? • How many curies of tritium are being discharged through groundwater • Why calculate? • Account for released tritium to groundwater as part of ODC • How to calculate? • 1st Approximation Method – combine Darcy’s Law for groundwater flow and concentration data from sample results • Calibrated groundwater flow model

30. Tritium Flux Component – cont’d • Groundwater Discharge (Q) usingDarcy’s Law: • Q = groundwater discharge rate within plume [Liters/day]; • K = hydraulic conductivity from aquifer test [m/day]; • A = cross sectional area perpendicular to groundwater flow and plume [m2]; and • dh/dl = hydraulic gradient calculated from wells [unit-less].

31. Tritium Flux Component – cont’d • Tritium Flux [mCi/day] = Concentration x Groundwater Flow Rate • Concentration [pCi/L] – groundwater monitoring results • Groundwater Flow Rate [L/day] – Darcy’s Law • Apply unit conversions for mCi/day • Calculate tritium flux over REMP reporting period (quarterly, annually, etc.) for mCi released

32. Pitfalls to Avoid • Don’t treat all sites as equal • Don’t assume plumes are static (new releases, seasonal effects) • Don’t just look shallow – releases can occur below the water table (plant construction and geology) • Don’t drill deep in a potential source area unless rigorous controls are in place (cross-contamination) • Don’t expect all answers to questions after one round of investigation and sampling (phased approach)

33. Low-Flow Sampling - References • Puls, R.W., and Barcelona, M.J., April 1996, “Low-Flow (Minimal Drawdown) Ground-Water Sampling Procedures”. EPA Ground Water Issue. EPA/540/S-95/504. • U.S. Environmental Protection Agency, July 30, 1996. “Low Stress (low flow) Purging and Sampling Procedure for the Collection of Ground Water Samples from Monitoring Wells”. Region I. SOP #: GW 0001. • U.S. Environmental Protection Agency, May 2002. “Ground-Water Sampling, Guidelines for Superfund and RCRA Project Managers” stagnant water removal procedure. • Yeskis, D., and Zavala, B., May 2002. “Ground-Water Sampling Guidelines for Superfund and RCRA Project Managers”. Ground Water Forum Issue Paper. EPA 542-S-02-001.

34. Questions?