Technology:
In Situ Bioremediation
- Sodium lactate (electron donor) injection, extraction, above ground air stripping, and reinjection
- Weekly sodium lactate injections from January to September 1999; no lactate injections from September 2000 to February 2000 because electron donor had accumulated in the aquifer; March 2000 on, bi-monthly injections performed
- 492 ft-long treatment cell created by one injection well and one extraction well; extraction well operated continuously at an extraction rate of 190 L/min
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Cleanup Authority:
CERCLA
Technical Contact:
Lance Peterson
Technical Manager
Northwind Environmental, Inc
Telephone: (208) 528-8718 | DOE Contract:
Jim Wright
DOE EM50
Subsurface Contaminants Focus Area
Telephone: (803) 725-5608 |
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Contaminants:
VOCs
- TCE, PCE, 1,2-DCE
- Two mile long TCE plume;TCE concentration ranged from 100 mg/L at source zone to 5 ug/L at distal end of plume
- Source area (DNAPL) - about 200 ft in diameter |
Waste Source:
Injection of liquid wastes into the aquifer |
Type/Quantity of Media Treated:
Groundwater
- TCE plume located in a fractured basalt aquifer, 200 to 200 ft bgs
- Unconfined aquifer; groundwater flow - 0.35 to 0.79 ft/day |
Purpose/Significance of Application:
Demonstration of in situ bioremediation to treat groundwater contaminated with VOCs |
Regulatory Requirements/Cleanup Goals:
No specific cleanup levels identified for the demonstration |
Results:
- After one year of operation, TCE levels were to non-detectable levels in a number of wells, including the original injection well and the three monitoring wells where TCE concentrations were the highest
- Monitoring data indicate that TCE is being degraded by natural attenuation |
Cost Factors:
Estimated net present value of implementing ISB at TAN for 15 years - $35,410,000, including $3,750,000 in capital cost, $31,508,000 in O&M cost and $152,000 in D&D cost |
Description:
At the Test Area North (TAN) at INEEL, liquid wastes containing solvents and radionuclides were injected into an aquifer between 1953 and 1972, resulting in groundwater contamination at the site. TCE, PCE, and 1,2-DCE and radionuclides are present in the groundwater, and the contaminant plume is about two-miles ling and 200 to 450 ft deep.
In 1999, a demonstration of ISB was initiated at the TAN site to treat the source area of the contaminant plume and the more dilute dissolved plume with natural attenuation. Sodium lactate was injected into the subsurface using one injection well and extracted using one well located downgradient of the source to create a treatment cell about 492 ft long. After a one-year period, TCE concentrations in a number of wells were reduced to non-detecable levels and evidence of natural attenuation was observed in the dissolved plume. The system was continuing to operate through 2001. According to DOE, the technical applicability of ISB is dependent upon site geology, conentrations of native nutrients, and the natural oxidation potential of the subsurface. |
