Laserfiche WebLink
MAY 14 9333 <br /> First Quarter 1993 Groundwater Monitoring Report ENVIRONMENTAL HEALTH <br /> Tri-Valley Growers, Thornton, California PERMIT/SERVICES <br /> Page 2 <br /> toluene, ethylbenzene, xylenes (BTEX), and total petroleum hydrocarbons as gasoline (TPHG), <br /> by EPA methods 8020 and modified 8015, respectively <br /> Analytical Results <br /> No dissolved gasoline hydrocarbon constituents were reported at or above detection limits in <br /> monitoring wells MW 1 through MW3, MWS, and MW6 <br /> Influent and effluent samples from the pumping well (MW4) were collected for analysis of <br /> BTEX and TPHG on March 25, 1993 Analytical results indicate a decrease in TPHG and <br /> BTEX levels in the influent sample collected during this sampling round The samples collected <br /> from carbon filter 1 (TVGT EFFIC) and carbon filter 2 (TVGT EFF2C) did not contain any <br /> detectable analytes during this sampling round Influent BTEX and TPHG concentrations over <br /> time are plotted on Figures 6 and 7 <br /> Laboratory analyses were performed by RESNA Environmental Laboratory (FLAP No 1211) <br /> The analytical results are summarized in Table 2, the laboratory reports and chain-of-custody <br /> documentation are presented in Attachment 2 <br /> Remediation System Performance <br /> atrori`system`was-shut`down-on-February-l-9-due-to-a-ieak-in-the-lead-carbon fIt r <br /> hole caused b corrosion, was discovered in the bottom of the carbon canister The car on <br /> was-rgAaced-mid-the-system-'waw perational on March 2, 199 , <br /> A review of previous analytical results from the removal of the underground gasoline storage <br /> tanks and the monitoring well installations at the site indicated that water samples collected from <br /> tank excavation T4/T5 and monitoring well MW4 contained elevated levels of TPHG and BTX <br /> All other water samples were nondetect for the gasoline hydrocarbons and constituents Since <br /> only two data points were available, the area of impaction was not estimated Thus, the amount <br /> of dissolved hydrocarbons in the groundwater beneath the site cannot be estimated, nor can the , <br /> treatment time necessary to bring the hydrocarbon levels to nondetect be estimated <br /> i <br /> Overall, analytical results support the effectiveness of the system Historical sampling results <br /> show fluctuating influent hydrocarbon concentrations which may be attributed to fluctuating <br /> water table elevations However, for the most part, laboratory results indicate that influent <br /> TPHG and BTEX concentrations have been significantly reduced since system start-up Based <br /> ypan­a�_naverage flow rate o �litersi�i�zte and an average influent gasoline hydrocarbon <br /> concentration�3,000µgrY;itis estimated that approximately 485,000 gallons of groundwa <br /> ave been treated and approximately 1 8 gallons of asoline h der -QarbQm-have-be a remove <br /> si ce rem latlon system start up in Mar 199 <br /> QRT}?RLY1tQMR1993 FNL <br />