In Situ Bioremediation
- Liquid microbial solution, manufactured by The Critter Company (TCC) and consisting of microbes (Pseudomonas, Bacillus, and Corynebacterium), oxygen emulsifier, surfactant, encapsulant, and nutrients was injected into the subsurface through monitoring and injection wells
- Five injections to date including: February 1999 - 150 gallons injected into 21 monitoring wells and 15 Geoprobe® injection points at pressures ranging from 5 to 20 pounds per square inch; March 1999 - 650 gallons injected into nine newly installed injection wells; December 1999 - 700 gallons injected into nine injection wells and three monitoring wells; March 2000 - 700 gallons injected into nine injection wells and four monitoring wells; and May 2000 - 700 gallons injected into nine injection wells and four monitoring wells
Debra L. Thoma
South Carolina Dept. of Health
and Environmental Control
2600 Bull St.
Columbia, SC 29201
Telephone: (803) 898-4362
Fax: (803) 898-4330
521 Clemson Road
Columbia, SC 29229
Telephone: (803) 699-1976
Fax: (803) 699-9863
MTBE, BTEX, Naphthalene
Leaks from an underground gasoline storage tank
Type/Quantity of Media Treated:
- Depth to groundwater is 4.32 to 6.92 feet below ground surface (bgs)
- Average hydraulic gradient is 0.078 feet/feet with a calculated seepage velocity of 6.42 feet per year
- No confining units were identified at the site
Purpose/Significance of Application:
Use of in situ bioremediation to treat MTBE in groundwater
Regulatory Requirements/Cleanup Goals:
wells used in setting the SSTLs.
- Total SSTLs (sum of individual SSTLs for each well) - MTBE - 120 ug/L; benzene - 20 ug/L; toluene - 2,615 ug/l; ethylbenzene - 1,741ug/L; xylenes - 5,471ug/L; naphthalene - 100 ug/L
Site-specific target levels (SSTLs) were established by SCDHEC for MTBE, benzene, toluene, ethylbenzene, xylenes, and naphthalene, with four monitoring
As of September 2000, the SSTL for ethylbenzene has been met; however MTBE, benzene, toluene, xylenes, and naphthalene remain above the SSTLs
- MTBE levels decreased by 96% (from 3,310 to 146 ug/L), while benzene decreased by 83% (2,571 ug/L to 435 ug/L); toluene by 66% (24,330 ug/L to 8,300 ug/L), and naphthalene by 84% (5,377 ug/L to 853 ug/L); xylene levels decreased following the injections in February and May 1999, then increased and were above pre-operational level as of September 2000
- The system will continue to be operated until all SSTLs have been met; the contractor projects that cleanup of the site will be completed by February 2001
The total cost for the cleanup of this site is $63,500
- The South Carolina Petroleum Cleanup Fund awarded the contract for the cleanup at this site as a fixed-price, lump sum with no change orders; no additional information on cost breakdown was available.
South Beach Marina is a gasoline dispensing station located in Hilton Head, South Carolina. In August 1995, a release was reported from the station's underground storage tank (UST). Groundwater at the site was found to be contaminated with MTBE, BTEX, and naphthalene. Data from 1998 showed concentrations of contaminants in groundwater as high as 1,320 ug/L for MTBE, 1,250 ug/L for benzene, 21,500 ug/L for toluene, 657 ug/L for ethylbenzene, 3,140 ug/L for xylenes, and 4,720 ug/L for naphthalene. A Corrective Action Plan (CAP) was implemented in May 1999 under Subtitle I of the RCRA program. The CAP included in situ bioremediation.
In situ bioremediation at the site was begun in February 1999 and has included five injections of a liquid microbial solution, manufactured by The Critter Company (TCC). The solution consisted of microbes (Pseudomonas, Bacillus, and Corynebacterium), oxygen emulsifier, surfactant, encapsulant, and nutrients, and was injected into the subsurface through monitoring and injection wells in February, March, and December 1999 and in March and May 2000. As of September 2000, the SSTL for ethylbenzene has been met. While reductions in levels have been observed for for MTBE, benzene, toluene, and naphthalene, these contaminants remain above the SSTLs. Levels of xylenes have increased above pre-operational levels. The system will continue to be operated until all SSTLs have been met, with the site contractor projecting completion of the remediation by February 2001.