Feroxsm Injection at Hunter's Point Shipyard, Parcel C, Remedial Unit C4, San Francisco, CA

Site Name:

Hunter's Point Ship Yard, Parcel C, Remedial Unit C4


San Francisco, CA

Period of

December 5 - 23, 2002


Field Demonstration

Chemical Oxidation using Feroxsm Injection
- 4 injection boreholes; 32 ft deep (below where DNAPL expected to be observed); injections performed from the bottom up to minimize potential DNAPL displacement downward and horizontally; injections conducted sequentially in each of the 4 boreholes; 3-ft intervals starting at 30 ft bgs, going to 10 ft bgs
- Injection process integrated pneumatic fracturing and Feroxsm delivery, with nitrogen gas used as both the fracturing and injection fluid; ZVI slurry (1 kg ZVI powder to 1 gal water) injected at pressures ranging from 40 to 180 psig; about 16,000 lbs of ZVI injected during the demonstration

Cleanup Authority:
Not identified

Mr. Patrick Brooks
Remedial Project Manager
Southwest Division
Naval Facilities Engineering Command
San Diego, California

Volatiles-Halogenated, Trichloroethene (TCE), DNAPL
- Volatile organic compounds (VOCs), primarily TCE; TCE concentrations in groundwater as high as 88,000 µg/L

Waste Source:
Leaks from underground storage tanks, and wastes from painting and degreasing operations

Type/Quantity of Media Treated:
- Estimated subsurface volume treated was 1,683 cubic yards (based on a treatment area of about 1,818 ft2 and extending from the top of the water table of 7 ft bgs to 32 ft bgs
- Two aquifers (A and B) and one bedrock water-bearing zone; hydrogeology characterized by shallow bedrock overlain predominantly by artificial fill material with variable hydraulic conductivity; Aquifer A hydraulic conductivity ranged from 26.6 to 43 ft/day
- Groundwater flow directions are variable, generally trend south to southwest; depth to groundwater ranged from 6.2 to 6.8 bgs

Purpose/Significance of Application:
Field demonstration to evaluate use of Feroxsm injection to treat chlorinated VOCs

Regulatory Requirements/Cleanup Goals:
- Primary objective of the demonstration was to evaluate the cost and performance of Feroxsm injection in treating chlorinated VOCs in source areas at Hunter’s Point
- Other objectives included evaluating the percent reduction of TCE, PCE, 1,2-DCE, vinyl chloride, total chlorinated ethenes, chloroform, and carbon tetrachloride; no specific cleanup goals were identified

- Groundwater sampling conducted prior to the injections and at 2, 6, and 12 weeks after injection
- The overall reduction percentages within the treatment zone for the VOCs were: TCE (99.2 percent), PCE (99.4 percent), cis-1,2-DCE (94.2 percent), vinyl chloride (99.3 percent), total chlorinated ethenes (99.1 percent), chloroform (92.6 percent), and carbon tetrachloride (96.4 percent)
- Horizontal zone of influence (based on ORP and other parameters) - extended at least 15 ft from the injection boreholes

Cost Factors:
- Total cost of the field demonstration was $289,274 or $172 per cubic yard of the treatment zone
- Excluding costs for sampling, analysis, and management of demonstration-derived wastes, the total cost was $196,665, or $117 per cubic yard
- Economies of scale for certain cost elements, such as mobilization and demobilization, could result in somewhat lower unit costs for larger-scale applications

Hunter’s Point Shipyard (HPS) is located in the southeastern portion of San Francisco. The 928-acre facility operated from 1869 through 1986, as a ship repair, maintenance, and commercial facility; in 1991 the facility was designated Navy for closure under the federal Base Closure and Realignment Act.

Parcel C, located in the eastern portion of HPS, was identified as having several groundwater plumes, with a chlorinated solvent plume (primarily TCE) located beneath Remedial Unit-C4 (RU-C4). Ferox injection is a patented technology of ARS Technologies, Inc. for in situ subsurface remediation of source areas of chlorinated VOCs. The Feroxsm technology involves injection of liquid atomized zero-valent iron (ZVI) powder into targeted subsurface zones, using a packer system to isolate discrete depth intervals within open boreholes.

A field demonstration of Feroxsm injection was conducted at HPS RU-C4 to evaluate the use of the technology to treat chlorinated solvents in groundwater. The demonstration involved the use of 4 boreholes and the use of an injection process that integrated pneumatic fracturing and Feroxsm delivery (nitrogen gas used as both the fracturing and injection fluid). Results of the demonstration showed reductions in concentrations of chlorinated solvents, including DNAPL, of as high as 99.4 percent. It was noted that most of the reduction in TCE concentrations occurred during the first 3 weeks of the demonstration. For future applications, it was suggested that less monitoring would be needed than was performed for the demonstration.