Laserfiche WebLink
L � <br /> initiate removal of dissolved hydrocarbons from the groundwater. In a response letter <br /> dated 16 March 2005,the SJCEHD rejected the IRAP prepared by Stratus. SECOR was <br /> subsequent y retained b Joe's Place to assume responsibility for the investigation and <br /> remediation at the site. <br /> On May 2, 2005, SECOR submitted a revised IRAP to the SJCEHD proposing to conduct <br /> pump tests on wells MW-2, MW-3, and MWO-1X. The results of the pumps tests were <br /> used to estimate hydrogeologic properties in the site vicinity and in the evaluation of <br /> groundwater extraction as an interim remedial action measure for the site. In a letter <br /> dated 31 May 2005,the SJCEHD approved SECOR's revised IRAP and also requested <br /> that SECOR complete the scope outlined in the approved work plan submitted by Stratus <br /> on January 5, 2005. The results of the pump test were reported in SECOR's Additional <br /> Assessment Report dated June 27, 2006. <br /> 3.1 Pump Test Results <br /> SECOR conducted step-drawdown and constant discharge pumping tests in <br /> groundwater monitoring wells MWO-1X, MW-2, and MW-3 to determine <br /> hydrogeologic properties at the Site. The following results were obtained: <br /> Well ID Constant Maximum Duration Amount Average Mass of <br /> Discharge Drawdown of Test of GW MTBE MTBE <br /> Rate in Well (hrs) Extracted Conc Removed <br /> (gpm) (ft) (gallons) (ug/L) (grams) <br /> MWO-1X 6.0 14.68 4.4 1,538 196 1.14 <br /> MW-2 6.3 2.22 6 2,169 87 0.714 <br /> MW-3 5.0 7.83 6 1,715 240 1.55 <br /> Based on these results, SECOR estimated an effective radius of capture along the <br /> northern downgradient edge of the site to be approximately 127 feet. Based on the <br /> limited mass of MTBE removed compared to the high volume of groundwater <br /> produced, SECOR did not recommend groundwater pumping as an effective remedial <br /> alternative. However, as an interim remedial measure, groundwater pumping can <br /> prove effective to limit the amount of MTBE that migrates offsite. <br /> 4.0 APPLICABLE CLEAN-UP GOALS <br /> Although applicable clean-up goals for this site have not yet been established, the <br /> following guidance levels have been established by regulatory agencies: <br /> • The Environmental Screening Level (ESL) for MTBE in shallow or deep soil <br /> where groundwater is not a current or potential source of drinking water is <br /> 1800 ug/L. The ESLs were established by the Regional Water Quality <br /> Control Board(RWQCB) San Francisco Bay Region in their guidance <br /> ERG,0406 Page 3 IRAP <br />