WORK PLANS_FILE 2 - Laserfiche WebLink

Home Browse Search

Confirmation Soil Vapor Survey Workplan Moore Petroleum Bulk Plant,5491 F Street,Banta,California Page 6 PROPOSED SOIL VAPOR SURVEY Apex proposes to conduct a soil vapor survey at the subject site to confirm the absence of fugitive soil vapors in the vadose zone and the reported concentration of benzene reported above the Region 2 Environmental Screening Level during the October 31, 2007 SVS at 13 parts per billion by volume (Table 2). The soil vapor survey will include the installation of five temporary soil vapor survey points (SVP-14 through SVP-18) located on Figure 3. The soil vapor survey will include four temporary vapor probes around the onsite commercial building and one temporary vapor probe located at the border between the site and the closest nearby residence (Rhodes Residence). SOIL VAPOR POINT FIELD PROCEDURES Soil vapor sampling will be conducted using a whole-air active approach. The whole-air active approach involves the forced movement of bulk soil atmosphere from the sampling horizon to a collection device through a probe. Soil vapor samples will be obtained through shallow driven points, approximately 5 to 7 feet bgs. Apex will hire a private line locator prior to drilling to avoid striking any underground utilities. A direct-push rig will be used to advance the borings and collect soil vapor samples. The drill rod will be driven to the desired sampling depth then pulled back to expose the soil vapor probe intake. Hydrated bentonite will be used to seal around the drill rod at the surface to prevent ambient air intrusion into the subsurface. Using a sample pump with a flow rate of less than 200 milliliters per minute, at least three purge volumes will be purged through the system. After the initial three purge volumes have been removed,a photo ionization detector(PID)will be used to determine when a sample, with maximum concentrations, should be obtained. If concentrations remain below detection limits through seven purge volumes a sample will be collected at that point. After the vapor probe locations have been successfully purged, a 1 liter Summa canister will be connected to the vapor probe tubing with an air-tight seal. To confirm that the seals are air-tight, Difluoroethane will be used as a leak detectant and will be sprayed continuously around the sampling apparatus with an aerosol can, and analyzing for difluoroethane. Once sampling has been completed at each location,the probe will be withdrawn and decontaminated before moving to the next location. Analytical Procedures Soil vapor probe samples will be submitted under chain-of-custody documentation to a state- certified analytical laboratory for analysis of the following: I