In Situ Thermal Desorption (ISTD) Remediation at the Terminal One Tank Farm:

San Francisco Bay, Richmond, California

Site Information: The City of Richmond’s 14 acre (5.6 ha) site, known as the former Terminal One, was operated as a shipping and bulk storage terminal from about 1915 to the 1980s. The portion of the property being treated is known as the “Southwest Tank Farm” where solvents and petroleum products were stored in above ground tanks. The total treatment volume was approximately 6,700 cubic yards (5,120 m3); of which, a small portion was under a warehouse that will be demolished.

Brownfields Context: The Southwestern Tank Farm is slated to become a recreational area as part of a 250 unit residential community after site cleanup is completed.

Geology: Soil within the thermal treatment area is composed of bay mud, a dark greenish gray lean clay with minor amounts (<5%) of sand. A 2-3 ft (0.6-1 m) layer of fill exists above the bay mud. Thin interbedded layers with abundant shells (a few inches thick) have also been observed. The average thermal treatment depth was approximately 20 ft (6 m) below ground surface (bgs).

Groundwater: Depth to water beneath the site is approximately 3 ft (1 m) bgs.

Contaminants of Concern (COCs) were as follows: tetrachloroethene (PCE); trichloroethene (TCE); cis-1,2 dichloroethene (DCE); and vinyl chloride (VC).

ISTD Wellfield; An adjacent marina is visible in the background

ISTD Wellfield Inside of Former Shipping Warehouse

Approach: • In Situ Thermal Desorption

(ISTD)

• Minimum target temperature of 100°C

• Spacing between thermal wells: 12 ft (3.7 m)

• Thermal wells: 139

• Granular activated carbon and potassium permanganate for off-gas treatment.

• Well depth: 22 ft (6.7 m) bgs

Site Owner: Richmond, CA Redevelopment Agency

Consultant: Geomatrix Consultants (now AMEC)

Results:• All remedial goals met

• Completed on time and on budget

For further information:

TERRATHERM, Inc.

151 Suffolk LaneGardner, MA 01440

(978) 730-1200info@terratherm.comwww.terratherm.com

In Situ Thermal Desorption (ISTD) Remediation at the Terminal One Tank Farm:

San Francisco Bay, Richmond, California

Heating Method:In Situ Thermal Desorption (ISTD)

Location: Richmond, CA

Project Staffing: As General Contractor, TerraTherm provided all project design, construction, operation and equipment.

Subcontracting: TerraTherm subcontracted for construction labor, drilling, and electricians.

Project Summary: Site mobilization occurred in late January 2005, and construction was completed in May 2005. Startup of the ISTD system occurred on schedule in early-June 2005 and treatment was completed on time (100 days) and on budget in September 2005. All remedial goals were met (see table below). Demobilization from the site was completed in November 2005.

In Situ Thermal Desorption was shown to be highly effective for treatment of chlorinated solvents in a tight clay layer below the water table. Soil concentrations of PCE were reduced from as high as 2,700 mg/kg to an average concentration of 0.012 mg/kg within 110 days of operation. Similar effectiveness was documented for TCE, 1,2-DCE, and vinyl chloride. No signs of contaminant spreading laterally or vertically were observed.

An analysis of the energy balance revealed that 45% of the energy was used to heat the subsurface to the target temperature. Another 53% was necessary to boil groundwater, creating 594 pore volumes of steam during the 110 days of heating and treatment. This steam generation process occurred within the clay throughout the TTZ, and was the dominant remedial mechanism. The steam migrated laterally towards the ISTD heaters, into a small dry zone that allowed the steam to migrate upward along the heaters to the vadose zone, where the steam was captured by a vacuum system. Effective thermal treatment must be based on (1) a thorough energy demand analysis accounting for both the energy needed to heat the site and the energy needed to boil groundwater, and (2) a robust design that allows the generated steam to migrate towards extraction locations rather than towards the cooler region where it either builds pressure or condenses.

Summary of Results:

For further information:

TERRATHERM, Inc.

151 Suffolk LaneGardner, MA 01440

(978) 730-1200info@terratherm.comwww.terratherm.com