Site Name:

Naval Air Station Pensacola

Location:

Pensacola, Florida

Period of
Operation:

November 1998 to May 1999

Cleanup
Type:

Field demonstration

Vendor:

Mattehew Dingens
Geo-Cleanse International, Inc.
4 Mark Road, Suite D
Kenilworth, NJ 07033
Telephone: (908) 206-1250
E-mail: geocleanse@earthlink.net

Technology:
In-Situ Chemical Oxidation using Fenton's Reagent
- Geo-Cleanse's patented process for in situ chemical oxidation conducted in two phases
- Fenton's reagent - hydrogen peroxide (50%) and an equivalent volume of ferrous iron catalyst
- Phase I injected 4,089 gallons of hydrogen peroxide and similar volumes of reagents through 14 injection wells at a depth of 10-40 ft bgs
- Phase 2 injected 6,038 gallons of hydrogen peroxide and similar volumes of reagent through 10 injection wells (9 old, 1 new), totaling 10,127 gallons; phosphoric acid was added to the reagent mix to stabilize the hydrogen peroxide
- Operating parameters included injection rate of 0.25 - 3 gpm, injection pressure of 5 - 110 psig, pH <8, and CO2 evolution of 5% - >25%

Cleanup Authority:
RCRA Corrective Action

Contaminants:
Chlorinated Solvents
- TCE primary target for demonstration
- Maximum concentration of TCE 3,600 ug/L

Waste Source:
Unlined sludge drying bed

Type/Quantity of Media Treated:
Groundwater
- 16,500 gallons of groundwater in the source area
- Depth to groundwater 0-4 ft; contaminants detected in groundwater 35-45 ft bgs
- Soil classified as fine to medium quartz sand
- Properties included porosity >15%; pH 3-6; hydraulic conductivity 2-44 ft/day; dissolved iron >500 mg/L

Purpose/Significance of Application:
Field demonstration of in situ chemical oxidation using Fenton's reagent to treat chlorinated solvents

Regulatory Requirements/Cleanup Goals:
- Evaluate effectiveness of in situ chemical oxidation in treating chlorinated solvents
- No specific cleanup goals were identified

Results:
- Phase I reduced TCE concentrations from as high as 3,600 ug/L to 485 ug/L in source area well
- This was considered insufficient reduction; Phase I performance was attributed to elevated concentrations of ferrous iron in the treatment area, likely due to a historic spill of sulfuric acid
- Phase II reduced TCE concentrations from 460 ug/L to <5 ug/L in source area well

Cost Factors:
- Actual costs for this demonstration, reported by Geo-Cleanse, were $178,338, consisting of $97,018 for capital and $81,320 for O&M; these costs do not include electrical power or water supply, which were provided by NAS Pensacola

Description:
Naval Air Station (NAS) Pensacola is a 5,800-acre naval facility located in the western portion of the Florida panhandle. Operable Unit (OU) 10, is located on 26 acres of Magazine Point Peninsula in the northeast corner of the NAS, was the site of the former Industrial Wastewater Treatment Plant (IWWTP). The IWWTP treated wastewater from operations such as painting and electroplating, as well as organic solvents and acids, and included an unlined sludge drying bed. A groundwater recovery system had been operated for more than 10 years under a RCRA corrective action program to control migration of contaminated groundwater. In situ chemical oxidation using the Geo-Cleanse patented process was evaluated for its ability to reduce concentrations of chlorinated solvents in the source area, such that natural attenuation would be an effective remedy for down-gradient groundwater.

The Geo-Cleanse process used Fenton's reagent (hydrogen peroxide (50%) and an equivalent volume of ferrous iron catalyst) and was conducted in two phases at OU-10. A total of 10,127 gallons of hydrogen peroxide and similar volumes of reagents were injected under pressure through 15 wells at a depth of 10-40 ft bgs. Over the two phases, the concentration of TCE was reduced from 3,600 ug/L to <5 ug/L, as measured in a source area monitoring well. Elevated concentrations of ferrous iron in the groundwater, due to a historic sulfuric acid spill, limited the effectiveness of the first phase of injections. In the second phase, phosphoric acid was added to the reagent mix to help stabilize the hydrogen peroxide in the presence of elevated ferrous iron concentrations. The actual costs for the demonstration were $178,338, and additional injections were not planned for this site.

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