ARCHIVED REPORTS_XR0003911 - Laserfiche WebLink

Home Browse Search

t E w REMEDIAL ACTION PLAN USA STATION#65 - LODI NOVEMBER, 1995 6.3 OPTION III- Excavation With Off-site Disposal/Treatment Based on the previous investigations,it is estimated that the hydrocarbon impacted soil extends to a depth of up to 50-feet bgs. Due to the location of the TPH impacted soil zone, excavation activities would likely require removal of the US Ts,product piping, and aboveground structures. k The major physical obstructions associated with this option, combined with the excessive cost and loss of daily retail operations make it impractical, and therefore,Option III was not retained for further consideration. 6.4 Recommended Remedial Action Alternative Following a review of existing site geologic and hydrogeologic characteristics, the VES well ' testing results, the magnitude and extent of the TPH impacted soil,and the analysis of remedial action alternatives, Park has recommended design and installation of a soil vapor extraction (SVE) system equipped with off-gas treatment for the destruction of petroleum hydrocarbon vapors, acid limited oxidation of the groundwater in MW-3 and MW-4 using either air sparging or the addition of an oxygen releasing compound such as "ORC!! by Regenesis Bioremediation Products.;Oxidation of the groundwater should enhance hydrocarbon degradation and therefore ' increase the effectiveness of the site remediation. Vapor extraction technology is proven to remediate both soil and groundwater and to remove TPH from the groundwater table,if present. Recent vapor extraction testing at the site indicated the radius of influence from MW-8 should extend well beyond the limits of the currently identified plume of impacted soil and groundwater, and the zone of influence from S-1 and S-2 should extend beyond the limits of the identified soil plume and nearly to the limits of the currently identified groundwater plume (Western Geo-Engineers, April 17, 1995). In addition, to further enhance volatilization and potentially stimulate biological degradation periodic air sparging may be done in MW-3 and MW-4; or,to increase the amount of oxygen available in the groundwater, an oxygen enriching compound such as ORC may be released in MW-3 and/or MW-4. If f sparging is done the wells will be sparged for several hours during routine operation and { maintenance (O&M) visits. Sparging will be done with a portable compressor and airline that is lowered 4,-to 5-feet below the static water level. If an oxygen enriching compound is added, routine O&M will include sampling to monitor the effectiveness of the compound. Vapor phase hydrocarbon compounds that have been volatilized from the vadose zone soils will be conveyed to a catalytic oxidizer (oxidizer) and destroyed. Prior experience from operating 1 vapor extraction systems at other similar sites suggests that the proposed vapor extraction system can remove up to 200 pounds or more of hydrocarbon vapor per day. The oxidizer will operate under a temporary SNUAPCD permit. It is anticipated that the initial TPH.concentrations in the process gas may be close to 15,000 ppm v/v. As remediation proceeds and as TPH concentrations decline, an alternate off-gas treatment system may be utilized. This alternate system may include a blower and a vapor phase carbon treatment unit.