ARCHIVED REPORTS XR0006021 - Laserfiche WebLink

Home Browse Search

Quarterly Groundwater Monitoring,Results of Verification Soil Borings,and Closure Request Report Moore Petroleum, 1399E Yosemite,Ave,Manteca,CA July 1, 1996 ' Page 4 of Rio Vista, California, using conventional, hollow-stem augers The drilling and all field work was conducted according to the Apex Standard Operating Procedures (SOP)included as ' Appendix A The two soil borings were drilled at an angle of 30 degrees with respect to vertical in a direction ' towards the former tank basin to a total drilled depth of 30 feet, which corresponds to 26 vertical feet below surface (bs) Apex personnel collected soil samples at drilled depths of 20, 25 and 30 feet below surface (bs),this corresponds to 17, 22 and 26 vertical feet bs All samples were submitted, under chain-of-custody,to Sparger, a state-certified analytical laboratory The soil samples were analyzed for TPH, as gasoline, and BTEX All six soil samples collected were ' below laboratory detection limits for all constituents analyzed Laboratory analytical reports and chain-o£custody forms are included in Appendix E Soil boring logs are included as Appendix F ' 4.0 SITE CLOSURE REQUEST 4.1. Initial estimate of TPH, as gasoline, in soil A mass balance analysis was performed on the subject site to compare estimated quantities of ' TPH, as gasoline, initially present in soil surrounding the former tank locations as compared to the quantity of TPH, as gasoline, extracted during the operation of the vapor extraction system Figures 5A through 5E show TPH, as gasoline, as iso-concentrations at intervals of 5 feet to a ' total depth of 25 feet below surface, respectively Groundwater levels beneath the site range from 18 to 25 feet bs This compilation of five figures was created using initial soil analytical results collected when the soil borings and monitoring wells were installed at the subject site These ' figures, together, define the initial vertical and lateral extent of TPH, as gasoline, concentrations at the subject site Appendix G contains historical analytical results for soil from the installation ' of the monitoring wells and soil borings at the subject site Calculations were performed based on the historical soil analytical results to estimate the ongmal quantity of TPH, as gasoline, in the soil at the subject site at the time in which these borings were drilled It was estimated that approximately 590 pounds of TPH, as gasoline, were present in the soils surrounding the former tank basin at the time in which the soil borings were installed at the subject site,between August 1988 and April 1993 Calculation are contained in Appendix H 4.2 Estimate of TPH, as gasoline, extracted through vapor extraction In April of 1993, Aegis installed a vapor extraction system at the subject site which extracted vapors from monitoring well MW-113 The vapor extraction system was manufactured by Remediation Services International(RSI) and consisted of an internal combustion engine which 1