Technology:
Electrokinetics
- Two 1/8-acre test cells; one cell (#1) contained the two former waste lagoons and the surrounding berms, and was an artificially confined treatment area
- The second cell (#2) was an unconfined treatment area that was open to groundwater and tidal effects
- Operations within test cell #2 were never initiated due to performance problems observed in cell #1
- An electrically nonconductive sheet pile barrier wall was installed to a depth of 20 feet around the perimeter of cell #1
- Three rows of anode wells and two rows of cathode wells were installed to a depth of 10 ft; initial current density was 0.2 mA/cm2
- By 5/98 (3 months of operation), the size of the test area was reduced (1/16 acre), and the current density was increased from 0.2 mA/cm2 to more than 0.33 mA/cm2
- In 10/98 (22 weeks of operation), the field demonstration was temporarily suspended
- From January to June 1999, system operation resumed in a further reduced area (approximately 500 ft2)
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Cleanup Authority:
Not identified
Site Contact:
Not identified
| Regulatory Authority:
Not Identified |
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Contaminants:
Heavy metals
- Total concentrations of chromium up to 25,100 mg/kg and cadmium up to 1,810 mg/kg
- TCLP concentrations of chromium were nondetect and cadmium were 10.5 mg/L |
Waste Source:
Lagoons used for wastewater discharges from electroplating and metal finishing activities |
Type/Quantity of Media Treated:
Soil
- Soil type was sandy soil and sediment, with 85% sand, 7% gravel, 6% silt, and 1% clay
- Soil properties included pH of 5.84, total organic carbon of 6,390 mg/kg, hydraulic conductivity of 0.045 cm/sec, and cation exchange capacity of 3.9 |
Purpose/Significance of Application:
Field demonstration of electrokinetics for treatment of metals in a sandy soil |
Regulatory Requirements/Cleanup Goals:
- Metals - meet TCLP levels and California state total threshold limit concentration, and soluble threshold limit concentration levels |
Results:
- Analytical results of multiple soil and pore fluid samples were used to track the movement of the heavy metals over time
- October 1998 results indicated that chromium was migrating towards the cathode
- June 1999 results indicated that cadmium was moving toward the surface and towards the cathode region, and that chromium was moving toward the cathode region
- The electrokinetic system caused there to be elevated levels of trihalomethanes and free chlorine in the electrolyte solution, with concentrations as high as 165,000 æg/L chloroform, 200,000 æg/L acetone, and 8500 æg/L bromodichloromethane
- Concentration data were not provided |
Cost Factors:
Not provided |
Description:
The U.S. Army Environmental Center and the Engineer Research and Development Center of Waterways Experiment Station conducted a field demonstration of electrokinetics at a metal-contaminated site at Site 5 of Naval Air Weapons Station Point Mugu, California. NAWS Point Mugu comprises approximately 4,500 acres, and is located approximately 50 miles northwest of Los Angeles. Site 5, the Old Area 6 Shops, is a large area where electroplating and metal finishing operations were conducted. The area of study was approximately « acre in and around two former waste lagoons located in the center of Site 5. The lagoons are unlined and were used between 1947 and 1978 to receive wastewater discharge from electroplating and metal finishing activities.
Prior to the field demonstration, extensive laboratory testing was conducted to assess the potential effectiveness of electrokinetic extraction at NAWS Point Mugu. Results from laboratory studies showed that electrokinetics could successfully be applied to the demonstration site at NAWS Point Mugu. During the demonstration, electrokinetics increased the mobility of cadmium and chromium at this site.
Operation of the electrokinetic extraction system at the NAWS Point Mugu site is continuing to identify and further assess the factors that limit the performance of the technology. According to USAEC, at its current stage of development, this technology is not considered to be sufficiently developed to be considered as a commercially available technology. Issues to be resolved prior to full-scale commercialization include formation of trihalomethanes; effects on naturally occurring ions; a methodology for predicting treatment performance; electrode design and its effects on electric field shape and intensity; and a methodology for determining the configuration of the electrodes under field conditions. |
