In situ chemical oxidation
- Former Cowboy: A total of 12 nested injectors were installed in the source area. Upon setting of the grout, a 10% (by weight) solution of permanganate was introduced under pressure into each injector. Up to 300 gallons per day of 1-2% solution were fed into the system during remediation. A series of injectors was installed downstream to control PCE that was mobilized into groundwater from soil in the source area.
- Niles Finest: A 10 percent (by weight) of sodium permanganate (NaMnO4) solution was injected into the surface of the 200-ft2 area on a 24-point grid pattern. 15-19 gallons of the NaMnO4 were injected at each injection point.
- Rummel Creek: A 0.5 to 2% KMnO4 solution was injected into the perched water bearing zone using direct push technologies. Injections were carried out four times over a one year period. A total of 837 pounds of KMnO4 was injected. Each injection point received injections at two depths:one approximately 5 ft from the bottom of the transmissive zone, and the other five to 10 ft above the first.
- Springvilla: The treatment technologies used at this site include ISCO, monitored natural attenuation, carbon adsorption, removal, and SVE. On October 11, 2004, 100 gallons of 4% sodium permanganate solution was injected through lower infiltration piping in source area excavation. Groundwater monitoring is ongoing. Injection of electron donor to initiate bioremediation is planned for 2005.
Contacts: Varied by site
Chlorinated Solvents: cis-1,2-DCE; PCE; TCE; 1,2-dichloropropane; trans-1,2-DCE); 1,1-DCE; 1,1,1-TCA); Vinyl Chloride
- Former Cowboy Cleaners: PCE - 1,900 µg/L
- Niles Finest: (Groundwater) PCE - 1 mg/L; TCE - 0.015 mg/L. (Soil) 1,1,1-TCA - 5.61 mg/kg; 1,1-DCE - 3.5 mg/kg; PCE - 1,300 mg/kg; trans-1,2-DCE - 0.865 mg/kg; TCE - 18 mg/kg; VC - 2.84 mg/kg; Chromium - 0.0015 mg/L
- Rummel Creek: (Groundwater) 1,1-DCE - 9.7 µg/L; cis-1,2-DCE - 2600 µg/L; PCE - 2,200 µg/L; trans-1,2-DCE - 20 µg/L; TCE - 610 µg/L; VC - 12 µg/L
- Springvilla: (Groundwater) 1,1-DCE - 6.8 µg/L; cis-1,2-DCE - 4 µg/L; PCE - 7,800 µg/L; TCE - 48 µg/L. (Soil) cis-1,2-DCE - less than 5 µg/kg; PCE - 130,000 µg/kg; TCE - 50 µg/kg
Waste and wastewater from dry cleaning operations
Type/Quantity of Media Treated:
Soil, Dense non-aqueous phase liquid (DNAPL), Groundwater
- Former Cowboy: Depth to groundwater: 25 ft bgs
- Niles Finest Cleaners: Depth to groundwater: 3.74 ft bgs (average); conductivity: 0.101 ft/day; gradient: 0.034 ft/ft
- Rummel Creek: Depth to groundwater: 18 to 23 ft bgs; conductivity: 4.2 to 9.2 ft/day; gradient: 0.0045 ft/ft
- Springvilla: Depth to groundwater: 5 to 13 ft bgs; conductivity: 5 to 10 ft/day (for gravel); gradient: 0.003 ft/ft
Purpose/Significance of Application:
Use of in situ oxidation technologies for remediation of chlorinated solvents in groundwater at drycleaner facilities.
Regulatory Requirements/Cleanup Goals:
- Former Cowboy Cleaners: Cleanup goals were not identified.
- Niles Finest Cleaners: Soil remediation objective for PCE was 704.1 mg/kg. Contaminants found in groundwater were below the groundwater remediation objectives.
- Rummel Creek Shopping Center: PCE - 5 µg/L; TCE - 5 µg/L; cis-1,2-DCE - 70 µg/L; trans-1,2-DCE - 100 µg/L; VC - 2 µg/L
- Springvilla Dry Cleaners: Reduce contaminant mass beneath building to reduce/remove soil source of groundwater contamination and to reduce vapor intrusion potential.
Former Cowboy Cleaners:
- Initial PCE concentration in the source area was 1,900 µg/L; after eight months of treatment, the concentration was
- In February 2003, the State of Colorado issued a No Action Determination Approval
Niles Finest Cleaners:
- For groundwater, results of post injection sampling indicated that PCE contamination increased to 56 µg/L 30 days after injection, and to 150 µg/L 60 days after injection.
- Post-injection soil sampling showed a decrease in PCE contamination. However, the 60-day post-injection sampling showed much higher concentrations, ranging from 2,000 mg/L to 2,800 mg/L, near the original hot-spot area
- Even though the rebound of groundwater contamination can be addressed by injecting additional NaMnO4, the Illinois Fund Administrator and the consultant decided to abandon the use of NaMnO4.
- Based on post-injection sampling, excavation has been proposed to address the soil contamination
- Rummel Creek Shopping Center:
- The maximum concentrations observed at the source wells prior to the injection of permanganate were 2,200 µg/L for PCE and 610 µg/L for TCE.
- The first KMnO4 injection reduced the concentrations in the source wells which ranged from non-detect to 79 µg/L for PCE and non-detect to 74 µg/L for TCE.
- The TCE and PCE concentrations were found to vary across the non-source wells, but the concentrations were generally decreasing.
- At the downgradient wells, the concentrations had either remained stable or had decreased.
Springvilla Dry Cleaners:
- Following the excavation of contaminated soil, PCE concentration observed in a monitoring well closest to the treatment area was approximately half the pre-injection concentration.
- Evidence of permanganate (manganese dioxide) has been observed at wells >300 ft downgradient of the treatment area.
- Groundwater monitoring will continue and an evaluation of the remediation system will be performed to determine whether to inject additional permanganate or to switch to a bioremediation approach using simple electron donor added to infiltration gallery. Additional injection to infiltration gallery is planned for summer or fall 2005.
Former Cowboy Cleaners and Rummel Creek Shopping Center: Cost data unavailable
- Niles Finest Cleaners: Design and implementation, including post-injection sampling: $32,285
Springvilla Dry Cleaners:
- Design and Planning: $8,000
- Implementation (through soil treatment and initial permanganate treatment): $95,000
- Cost for Operation and Maintenance (O&M): Approximately $3,000/year for vapor recovery system monitoring and analytical costs
ISCO using either sodium or potassium permanganate was conducted at five dry cleaner sites contaminated with chlorinated solvents, primarily PCE and TCE. The concentration of contaminants in groundwater varied by site with levels of PCE as high as 110,000 µg/L and TCE as high as 610 µg/L. The remediation involved in situ chemical oxidation at full-scale at both sites. The remediation involved in situ chemical oxidation at full-scale at all four sites.
Reductions in contaminant concentrations following treatment were observed at all the sites except one (Niles Finest Cleaners). At the Niles site, a rebound in PCE concentrations was observed in both soil and groundwater after the injection of oxidant. Excavation has been proposed for the contaminated soil as an alternative to chemical oxidation. A lesson learned with this application is that when utilizing chemical oxidation, rebound or increase of chlorinated solvents in groundwater should be carefully monitored, even where contamination in soil was the only initial concern.