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Explore the investigation history, challenges, and innovations in the Olin/Standard Fusee Case Study in California. Learn about the current cleanup efforts, aquifer testing, and groundwater flow analysis. Discover the complexities of characterizing perchlorate contamination and the methods used to address the issue.
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Perchlorate Monitoring in the Llagas Groundwater SubbasinSouth Santa Clara County, CaliforniaOlin/Standard Fusee Case Study Presented byMichael Taraszki, PG, CHG Engineering and Consulting, Inc.
Outline • Investigation History • Current Cleanup and Abatement Order (CAO) • Characterization Elements and Challenges • Status of Investigation
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
Perchlorate Non-Detect GW Flow
Perchlorate >4 mg/L <6 mg/L GW Flow
Perchlorate >6 mg/L GW Flow
All Perchlorate Results GW Flow
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
Hydrogeology Geology Chemistry Evaluate Existing Data CHARACTERIZATION Acquire New Data Identify Limitations
Soil Core Benefits: • Near In-Situ Conditions • Near 100% Recovery • Plastic Wrapping Allows for Labeling • Boxed for Long-Term Storage
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
Slug Test Results Shallow Intermediate Deep
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
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
CMT Installation: Step 2 Prepare 300-Foot CMT Coil
CMT Wellhead SevenMonitoring Ports Sand Drainage ProtectivePVC Sleeve
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
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
Cross-Section and Groundwater Elevations Northern Half
Cross-Section and Groundwater Elevations Southern Half
Offsite Perchlorate Shallow Aquifer
Offsite Perchlorate Intermediate Aquifer
Offsite Perchlorate Deep Aquifer
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
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