ARCHIVED REPORTS_XR0007910 - Laserfiche WebLink

Home Browse Search

SOIL VAPOR EXTRACTION PILOT STUDY REPORT San Joaquin County Montgomery Ward Auto Service Center Public Health Services Department 5400 Pacific Avenue Stockton CA Site Code 2163 ' the ideal VES unit for this site should be able to extract vapors at the flow rate of 200 to 300 scfm and at vacuuum pressures of about 140 to 160 in WC EAI believes that by adding the ' wells VEW-2 and VEW-2B into the VES system, the amount of air flow from the wells will increase sufficiently to not have to use too much dilution and yet be able to pull vapors from the wells at appropriate vacuum pressures ' 8 3 2 Companson of Inlet/Outlet Parameters In order to assess the effectiveness of the VES unit, EAI monitored operating parameters of ' the unit Figure 34 shows the concentration of vapors extracted by the unit for treatment, concentration of vapors after dilution with ambient, and concentration of vapors being emitted by the exhaust From this graph, it is obvious that the dilution had reduced the concentrations significantly and there was virtually no concentrations detected in the air emitted into the atmosphere ' Figure 35 shows the oxygen content of vapor at the inlet of the unit, after dilution and at the exhaust It is obvious that after dilution the oxygen content goes up significantly 9.0 FEASIBILITY STUDY EAI considered the following remedial options m In-situ Bioremediation ■ Ex-situ Bioremediation ■ Ex-situ Vapor extraction ■ Excavation and Offsite Disposal ■ In-situ Vapor Extraction In-situ bioremediation was considered inappropriate primarily due to the uncertainty in treatment methodology and the time taken to remediate the soils Ex situ bioremediation and ex situ vapor extraction were not considered feasible due to the facts that it will require a significant amount of aboveground space for treatment which is Iprobably not available at the site Therefore, only excavation and offsite disposal and insitu vapor extraction remained as Ipossible feasible alternatives These two methods are discussed in details below 9.1. Excavation and Disposal Based on the extent of impact it is estimated that a total of about 6500 cubic yards (cyds) of soil is impacted near the former UST location (a rectangular area of approximately 80 ft length and 55 ft width, extending from 5 ft bgs to 45 ft bgs) and a total of about 2600 cyds of soil are impacted near the former dispenser (a rectangular area of about 60 ft length and 40 ft width, extending from 10 ft bgs to 40 ft bgs) I IProject No 1232 - 15 - ENVIRONMENTAL AUDIT; INC �