Presentation on theme: "Remedial Strategy for Perchlorate-bearing Commingled Plumes at an Explosives Test Facility EPA Technical Support Project Meeting October 21, 2004 Speaker:"— Presentation transcript:
Remedial Strategy for Perchlorate-bearing Commingled Plumes at an Explosives Test Facility EPA Technical Support Project Meeting October 21, 2004 Speaker: Vic Madrid Lawrence Livermore National Laboratory Environmental Restoration Division UCRL-PRES-207684 This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.
Site 300 location map Location Map Site 300 Courtesy Kevin Mayer, US EPA, Region 9
Site 300 Raw Chemicals High explosives RDX or cyclonite: C 3 H 6 N 6 O 6 HMX or octogen: C 4 H 8 N 8 O 8 Potassium perchlorate: KClO 4 Ammonium perchlorate: NH 4 ClO 4 Mock Explosives: Ba(NO 3 ) 2 Nitric acid: HNO 3 Radionuclides Tritium: 3 H Depleted uranium ( 235 U/ 238 U < 0.007) Solvents & heat exchange fluids TCE Silicon oil (TKEBS/TBOS)
Site 300 Technical Operations HE Processing Facility Clarifier & Cloth Filter Open burn treatment facility Unlined lagoon HE Solid Waste Dry well Floor drain Septic system Open air detonation on firing table Device shipped offsite Raw Materials HE Liquid Waste Test Device Firing table gravel & shot debris disposed in unlined landfills
Site 300 Technical Operations HE Processing Facility Clarifier & Cloth Filter Open burn treatment facility Unlined lagoon HE Solid Waste Dry well Floor drain Septic system Device shipped offsite Raw Materials HE Liquid Waste Test Device Environmental Test Facility TCE used as heat exchange fluid
Data from CERCLA investigations 1,000+ boreholes ~ 70% continuously cored > 50% geophysical logs up to 550 ft depth 600+ ground water monitor wells 15 years of ground water monitoring data hydrographs covering drought to El Niño conditions broad range of chemical data including isotopes
Site 300’s commingled plumes 8 Operable Units 12 commingled plumes Low levels of perchlorate detected in nearly all plumes
Summary of perchlorate data From 1965 to 1975 about 2 tons of perchlorate were used at Site 300 Perchlorate monitoring began in January 1998 at the request of the RWQCB 2,520 ground water samples have been collected from 380 monitor wells and analyzed for perchlorate at 4 µg/L detection limit 730 perchlorate detections in 122 monitor wells Maximum result = 65 µg/L detected down gradient of a landfill pit The most widespread perchlorate contamination is located beneath the HE Process Area where it is commingled with VOCs, RDX, & elevated nitrate. In the northern part of Site 300 perchlorate is commingled with tritium, depleted uranium, and elevated nitrate.
Proposed remedial alternatives for perchlorate-bearing commingled plume Funnel & gate PRB Hydraulic Diversion Multi-component remedial alternatives to remove depleted uranium and perchlorate, prevent pit inundation, & recycle tritium 1) Hydraulic diversion system 2) In situ (PRB) using cow bone char or apetite & ion exchange resin 3) Ex situ (funnel & gate) using cow bone char or apetite & ion exchange resin 4) Recirculation of tritium-bearing effluent for ex-situ option in situ ex situ Draft Final Pit 7 Remedial Investigation/Feasibility for the Pit 7 Complex at Lawrence Livermore National Laboratory Site 300, December, 2004 UCRL-AR-202492-DR
Tnbs 2 Aquifer Conceptual Model B832 Cyn HE Process Area GSA 650 600 550 Unconfined Confined Discharge to alluvial aquifer Extent of Saturation GW Elevation Contours Recharge A A’
Tnbs 2 TCE (µg/L) 50 20510 30 40 TCE µg/L 5 10 20 30 40 50 10000 feet Former W-S Well 6 Mass Est. = 13 kg TCE source
Dissolved O 2 (mg/L) along cross-section A-A’ 4.6 4.1 7.6 5.8 7.2 0.8 0.2 <.2 0.3 1.0 1.1 1.4
Denitrification trend line Septic waste Soil 15 N (per mil) 18 O (per mil) Isotopic signatures of nitrate in groundwater and in potential source materials Harry R. Beller, Vic Madrid, G. Bryant Hudson, Walt W. McNab, and Tina Carlsen “Biogeochemistry and natural attenuation of nitrate in groundwater at an explosives test facility” Applied Geochemistry 19 (2004).
Excess N 2 along cross-section A-A’ Nitrate equivalents (mg/L) Harry R. Beller, Vic Madrid, G. Bryant Hudson, Walt W. McNab, and Tina Carlsen “Biogeochemistry and natural attenuation of nitrate in groundwater at an explosives test facility” Applied Geochemistry 19 (2004).
Ongoing ground water cleanup activities Currently operating 13 ground water treatment facilities 7 facilities treating perchlorate 2 new facilities planned for FY’05 will treat perchlorate
Key question… Given large-scale, dilute, multiple constituent plumes in low-yield aquifers, how do we develop cost-effective strategies for ground water extraction and treatment using available remedial technology and effluent disposal options?
GAC profiling results Treated 50,000 gallons @ 1-2 gpm flow rate using solar-powered GAC treatment unit ClO 4 - breakthrough after 20,000 gallons Effluent @ perchlorate breakthrough GAC Profile TCE = <0.5 µg/L < 0.5 µg/L RDX = <1.0 µg/L < 0.3 mg/kg ClO 4 - = 7.0 µg/L 47 µg/kg NO 3 - = 56 mg/L 178 mg/kg Sorption capacity of GAC for ClO 4 - based on this test = ~ 18 mg/kg or ~ 2 grams per 55 gallon drum of GAC
GAC perchlorate removal data Perchlorate breakthrough µg/L
Fixed film bioreactor Fixed-film bioreactor Designed to treat nitrate using denitrifying bacteria. Influent nitrate = 90 mg/L ( as NO 3 - ) Flow rate = 1-2 gpm Effluent nitrate < 1 mg/L at peak efficiency 8-hr residence time Acetic acid used as main nutrient source. Minimizes nitrate loading on IX resin.
Low-cost, solar powered treatment train with containerized wetland (CW) Solar-powered treatment train consisting of GAC, CW, & IX operates 10 to 15 hrs / day depending on sun angle. CW uses local indigenous plants to remediate nitrate and perchlorate. Influent = 10 to 15 µg/L ClO 4 - & 45 mg/L NO 3 - Flow rate = 1 gpm CW Effluent = < 4 µg/L ClO 4 - & < 10 mg/L NO 3 - at peak efficiency 15-hour CW residence time Avoid creating wetland habitat. Ion exchange polishing used to ensure compliance with effluent discharge requirements.
B854-PRX Perchlorate Performance Data GAC removal CW removal GAC removal CW removal Detection Limit IX polish
Ion exchange Sybron SR-7: nitrate-specific ion exchange resin Higher affinity for perchlorate than nitrate (i.e., selectively removes perchlorate from nitrate-bearing water). Influent = 40µg/L ClO 4 - & 100 mg/L NO 3 - Flow rate = 3 gpm Effluent = < 4 µg/L ClO 4 - & 20 mg/L NO 3 - Perchlorate-laden resin is extremely difficult to regenerate, so it is disposed of as hazardous waste.
Commingled plume treatment train Bioreactor GAC IX GAC TCE, RDX, ClO 4 -, NO 3 - ClO 4 - NO 3 - Bioreactor ClO 4 - NO 3 - IX NO 3 -
µg/L Replace IX resin IX polish Detection Limit B815-SRC Perchlorate Performance Data
Extraction well field management priorities Prevent plumes from migrating offsite Contain source areas Cost efficiency Preserve resource
Remedial Strategy Balance site boundary pumping with up gradient pumping. Hydraulically contain source areas. Minimize nitrate loading on IX resin to reduce waste disposal costs. Strategically inject treated effluent - reverse natural gradient at site boundary - flush source areas - preserve resource Demonstrate technical basis for MNA of nitrate.
Final well field design 817-PRX 815-PRX 815-DSB 817-SRC 815-SRC Extraction well Injection well
Acknowledgements Project Manager: Leslie Ferry Hydrogeology: Zafer Demir, Mike Taffet, & Walt McNab Analytical chemistry: Brad Esser, Bryant Hydson, & Jean Moran Microbiology: Harry Beller Environmental engineering: Rolf Halden*, Bill Daily Jr, & Matthew Verce Phytoremediation: Paula Krauter & Tina Carlsen * Johns Hopkins Bloomberg School of Public Health References for more information: Burge, Stephany and Rolf Halden, “Nitrate and Perchlorate Removal from Groundwater by Ion Exchange” UCRL-ID-135639, September 8, 1999. Paula Krauter, Bill Daily Jr., Valerie Dibley, Holly Pinkart, and Tina Legler. Perchlorate and Nitrate Remediation Efficiency and Microbial Diversity in a Containerized Wetland Bioreactor. Submitted to International J. of Phytoremediation June 17, 2004. UCRL-JRNL-204756. Harry R. Beller, Vic Madrid, G. Bryant Hudson, Walt W. McNab, and Tina Carlsen “Biogeochemistry and natural attenuation of nitrate in groundwater at an explosives test facility” Applied Geochemistry 19 (2004).