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Presented by Michael Taraszki, PG, CHG Engineering and Consulting, Inc.

Perchlorate Monitoring in the Llagas Groundwater Subbasin South Santa Clara County, California Olin/Standard Fusee Case Study. Presented by Michael Taraszki, PG, CHG Engineering and Consulting, Inc. Outline. Investigation History Current Cleanup and Abatement Order (CAO)

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Presented by Michael Taraszki, PG, CHG Engineering and Consulting, Inc.

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  1. Perchlorate Monitoring in the Llagas Groundwater SubbasinSouth Santa Clara County, CaliforniaOlin/Standard Fusee Case Study Presented byMichael Taraszki, PG, CHG Engineering and Consulting, Inc.

  2. Outline • Investigation History • Current Cleanup and Abatement Order (CAO) • Characterization Elements and Challenges • Status of Investigation

  3. Investigation History • Perchlorate Tested/Observed Beneath Morgan Hill Site in 2000 • Site Investigation Expanded to Include Offsite Private Wells • Continued Presence of Perchlorate Required Rapid Expansion of Monitoring Program • Over 200 Wells >PHG (6 mg/L) by 2004 • Only 33 Wells >PHG Currently

  4. Perchlorate Non-Detect GW Flow

  5. Perchlorate >4 mg/L <6 mg/L GW Flow

  6. Perchlorate >6 mg/L GW Flow

  7. All Perchlorate Results GW Flow

  8. Investigation Overview • Current Cleanup and Abatement Order Requirements • Characterization Elements • Lateral/Vertical Extent of Perchlorate • Background Concentration Evaluation • Establish GW Flow Directions, Chemical Signatures, and Aquifer Hydraulic Parameters • Characterization Challenges • Large Scale Project • Significant Technical Issues • Aggressive Schedule • Politically Charged Arena • Investigation Status

  9. Hydrogeology Geology Chemistry Evaluate Existing Data CHARACTERIZATION Acquire New Data Identify Limitations

  10. Detailed Logging of Soil Core

  11. Soil Core Benefits: • Near In-Situ Conditions • Near 100% Recovery • Plastic Wrapping Allows for Labeling • Boxed for Long-Term Storage

  12. Depth-Discrete Slug Testing

  13. Aquifer Hydraulic Testing • In-Situ Drill-String Slug Testing • Conducted During Drilling Activities • 208 Tests Performed to Date • Pneumatic Slug Testing • Conducted In Completed 1-Inch PVC Wells • ‘Passive’ Pumping Response Analysis • Continuously Recorded Water Levels

  14. Slug Test Results Shallow Intermediate Deep

  15. Installing Multi-LevelMonitoring Wells

  16. Mixture of Techniques Initial Borehole &PVC Couplet Second Borehole &CMT Well Depth (ft) 0 Result: Up To Nine Depth-Discrete Intervals at Each Location 100 Borehole 200 Casing 300 Screen 400 450

  17. Monitoring Well Design • Base Design Upon Geologic Log of Continuous Core • Target Zones with Highest Permeability • CMT Well Design Begins with Evaluation of First 300-Feet of Primary Borehole • PVC Couplet Designed • CMT Design Confirmed with Evaluation of Secondary Borehole • Designs Coordinated with RWQCB and SCVWD

  18. CMT Installation: Step 1Layout Work Area

  19. CMT Installation: Step 2 Prepare 300-Foot CMT Coil

  20. CMT Installation: Step 3Uncoil CMT Material

  21. CMT Installation: Step 4Install Monitoring Ports

  22. CMT Installation: Step 5Install Port Screens

  23. CMT Installation: Step 6Backfill Void Space

  24. CMT Installation: Step 7Install Bottom Plugs

  25. CMT Wellhead SevenMonitoring Ports Sand Drainage ProtectivePVC Sleeve

  26. PVC Couplet Wellhead (in progress)

  27. Completed Well Diagrams Initial Borehole &PVC Couplet Second Borehole &CMT Well Depth (ft) 0 Result: Up To Nine Depth-Discrete Intervals at Each Location 100 Borehole 200 Casing 300 Screen 400 450

  28. Depth-Discrete Groundwater Elevation and Analytical Data

  29. GW Elevation Evaluation • Monitoring Well Elevation Data Will Be Used to Identify: • Vertical Distinction of Aquifer Units • Local Pumping Influences • Depth-Discrete Horizontal Gradients • Utility of Supply Wells

  30. Cross-Section and Groundwater Elevations Northern Half

  31. Cross-Section and Groundwater Elevations Southern Half

  32. Offsite Perchlorate Shallow Aquifer

  33. Offsite Perchlorate Intermediate Aquifer

  34. Offsite Perchlorate Deep Aquifer

  35. Summary • Data Evaluation • Continuous Soil Core • Groundwater Flow Directions • Aquifer Hydraulic Parameters • Perchlorate Distribution/Chemical Signatures • Significant Challenges Being Addressed with Innovative Approaches • Sonic Drilling/Continuous Soil Cores • Multi-Level Monitoring Well Technology • Depth-Discrete Aquifer Testing • Aggressive Investigation Schedule

  36. Contact Information: Michael Taraszki 600 Grand Avenue, Suite 300 Oakland, California 94610 (510) 628-3222 mdtaraszki@mactec.com Petaluma Office: 5341 Old Redwood Hwy, Ste 300Petaluma, CA 94954 Phone: (707) 793-3800 Fax: (707) 793-3900 San Francisco Office: 28 Second Street, Suite 700 San Francisco, CA 94105 Phone: (415) 543-8422 Fax: (415) 777-9706 Sacramento Office: 4704 Roseville Road, Suite 108, North Highlands, CA 95660 Phone: (916) 332-5552 Fax: (916) 332-5559 www.mactec.com

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