Laserfiche WebLink
ArSAMA <br /> ' were collected Routine maintenance of the Thermal Oxidizer and remediation system was also <br /> conducted during this time <br /> Influent and effluent air samples were analyzed for benzene, toluene, ethylbenzene and xylenes <br /> (BTEX) and total petroleum hydrocarbons as gasoline (TPHG) using EPA method <br /> 50301801518020 All samples were sent to state-certified Sequoia Analytical laboratories in <br /> Redwood City, California Table 1 presents all vapor analysis laboratory data to July 8, 1992 <br /> Laboratory reports with chain-of-custody documents are presented in Attachment 11 <br /> Laboratory analyses of influent samples collected from the Thermal Oxidizer indicated that <br /> benzene and TPHG concentrations continue to decrease over time Effluent concentrations also <br /> decreased over time Influent TPHG vapor concentrations decreased from 6,800 µg/L to 290 <br /> µg/L from April to July Figure 5 shows the steady declining trend in the influent TPHG vapor <br /> concentration over time <br /> During the month of June, the influent vapor concentrations remained relatively constant at <br /> approximately 500 µg/L, indicating that the system had reached a point of diminishing returns <br /> The Thermal Oxidizer was shut down and removed on July 13, 1992 During Phase I, the vapor <br /> extraction system from April to July 8, 1992 had removed approximately 1160 pounds of TPHG, <br /> or approximately 149 gallons of gasoline from the subsurface <br /> ' Laboratory analyses has determined that influent vapor concentrations have significantly <br /> diminished from 6,800 to 290 µg/L. The Thermal Oxidizer was removed due to low influent <br />' vapor concentrations and replaced with the Carbon Adsorption System which will remove <br /> residual hydrocarbons from the subsurface <br /> R070792 TLP 5 <br />