ARCHIVED REPORTS XR0000780 - Laserfiche WebLink

Home Browse Search

Tosco Corporation,a subsidiary of Phillips Petroleum Company 4 Tosco Station#1205,16470 Cambridge Street,Lathrop CA June 26 2002 • During the 18-hour DPE event for wells MW-5, and MW-6, the applied vacuum ranged from 19 in of Hg to 19 5 in of Hg, and vapor extraction flow rates ranged from 69 10 cfm to 98 65 cfm The groundwater extraction flow rates ranged from 17 gpm to 2 0 gpm Groundwater elevations for wells MW-1, MW-2, MW-3, MW-7, and MW-4 decreased by 0 14 feet, 0 12 feet, 0 06 feet, 0 07 feet, and 0 02 feet, respectively FID readings collected from the vapor extracted from all wells ranged from 2,000 ppmv to 2,400 ppmv during the test Applied vacuum, vapor extraction flow rates, groundwater extraction flow rates, and influent FID readings are presented in Table 1 LABORATORY ANALYTICAL DATA Combined Well Results Laboratory analyses of soil vapor samples collected dunng the DPE tests are summarized in Table 2 Groundwater Results Groundwater samples were collected from wells MW-1, MW-2, MW-5, MW-6 and MW- 7 before and after the DPE test, and analyzed for TPHg, BTEX, and MtBE by the DHS LUFT method and fuel oxygenates using EPA Method 8260B TPHg, benzene and MtBE groundwater concentrations decreased in well MW-2 TPHg and benzene concentrations increased significantly in wells MW-1, MW-5, MW-6 and MW-7, possibly the result of groundwater extraction pulling the plume to wells MW-1, MW-5, MW-6 and MW-7 Below is a table showing the groundwater concentrations of TPHg, benzene, and MtBE in parts per billion (ppb) measured before and after the DPE event Refer to Tables 3 and 4 for a more complete list showing all analyte concentrations The bolded values indicate reduced analyte concentrations -WeU# TP* <-Ppb) Benzene(ppb) z iv tBB(ppb) ^� x Before DPE After DPE Before DPE After DPE Before DPE After DPE MW-1 <50 55 07 1 1 <2 5 <2 5 MW-2 800 250 31 48 90 68 MW-5 750 67,000 11 150 <25 <500 MW-6 <500 47,000 <5 0 164 460 <500 MW-7 5,000 17,000 25 48 <50 <100 EXTRACTED WATER PROFILING AND DISPOSAL During the tests approximately 11,870 gallons of groundwater were extracted from the site Extracted groundwater was temporarily stored in a holding tank and sampled on March 29, 2002 Extracted groundwater was analyzed for TPHg, BTEX, and MtBE by the DHS LUFT method, prior to disposal at Tosco's Refinery in Rodeo, California Laboratory analysis of extracted water detected TPHg at a concentration of 3,300 ppb,