Technology:
In Situ Bioremediation; Anaerobic Reductive Dechlorination
- Pilot studies consisted of molasses injection and air sparging/soil vapor extraction
- Full scale molasses injection system consists of 20 four-inch diameter injection wells, ranging in depth from 19 to 30 ft, completed in the overburden
- Molasses is added two times each day at variable concentrations and rates
- Eight additional wells are used for monitoring system performance
- This is a proprietary technology owned by ARCADIS Geraghty & Miller.
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Cleanup Authority:
CERCLA - ROD signed December 1996
Site Contact:
Not identified | EPA Remedial Project Manager:
Eugene Dennis
U.S. EPA Region 3
1650 Arch Street (3HS21)
Philadelphia, PA 19103-2029
(215) 814- 3202
E-mail: dennis.eugene@epa.gov |
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Contaminants:
Chlorinated solvents and heavy metals - TCE, DCE, VC, hexavalent chromium, cadmium
- Maximum concentrations measured in late 1996 were TCE - 700 ug/L, hexavalent chromium - 3,000 ug/L, and cadmium - 800 ug/L |
Waste Source:
Spills and leaks from plating operations; disposal in lagoons and wells |
Type/Quantity of Media Treated:
Groundwater
- Site geology consists of a sandy silt overburden overlying a fractured bedrock and a fractured limestone
- Target area for treatment is the shallow overburden to approximately 25 ft bgs, covering approximately 2 acres |
Purpose/Significance of Application:
One of the first applications of molasses injection technology on a full scale at a Superfund site. |
Regulatory Requirements/Cleanup Goals:
- The 1996 ROD specified the following cleanup goals for groundwater: TCE - 5 ug/L; 1,2-DCE - 70 ug/L; VC - 2 ug/L; Cd - 3 ug/L; Cr+6 - 32 ug/L; Mn - 50 ug/L |
Results:
- The pilot study showed that the technology was able to create strongly reducing conditions
- The baseline sampling event showed that anaerobic, reducing conditions were present only near two of the site monitoring wells
- Since the injection of reagent, the redox levels have decreased to anaerobic conditions in many of the wells that had previously indicated an aerobic environment, and cleanup goals have been met in some of the wells
- Analytical results for TCE, DCE, and VC for an area that was converted from aerobic to anaerobic show that TCE was reduced from 67 to 6.7 ug/L, a 90% reduction. The concentration of DCE initially increased, indicating the successful dechlorination of TCE, and then decreased to 19 ug/L
- Concentrations of TCE, DCE, and Cr+6 have been reduced to less than their cleanup goals in many of the monitoring wells at the site |
Cost Factors:
- ARCADIS Geraghty & Miller reported a total project value of $145,000 for the pilot study application at this site, including preparation of a work plan. - The costs for the construction of the full scale molasses injection system was approximately $220,000. Operation and maintenance, including monitoring, is approximately $50,000 per year. |
Description:
The Avco Lycoming Superfund site (Lycoming) is a 28-acre facility located in Williamsport, Pennsylvania. Since 1929, various manufacturing companies have operated at the site. Past waste handling practices have contaminated the site, including disposal of waste in wells and lagoons, and spillage and dumping of wastes from metal plating operations. In 1984, the state identified volatile organic compound (VOC) contamination in the local municipal water authority well field located 3,000 ft south of the site. A pump and treat system was installed in the mid 1980's. In May 1995, the PRP proposed the use of in situ bioremediation to replace the pump and treat remedy. Pilot studies of molasses injection and air sparging/soil vapor extraction (SVE) were conducted from October 1995 to June 1996. A new ROD, issued in December 1996, replaced the pump and treat remedy with in situ bioremediation, and a full-scale system has been operating at the site since January 1997. Construction of the air sparging/SVE system was suspended in the Spring of 1998, due to higher than anticipated water levels.
The use of molasses injection was shown to create an anaerobic reactive zone in an 18-month period where concentrations of TCE, DCE, and hexavalent chromium were reduced. According to the PRP contractor, this technology was shown to save substantial resources when compared to pump and treat. |
