Laserfiche WebLink
Sulfolane Remedial ' <br /> Investigation Work Plan <br /> ARCADIS Former Occidental Chemical Corporation <br /> Lathrop, California ' <br /> Concentrations of DBCP(15 pg/L)and sulfolane(8,500 pg/L)were detected in <br /> samples collected from well WS-1 located approximately 170 feet north-northwest of ' <br /> borings SB-3a and SB-24a during the September 2007 sampling event(CRA 2008). <br /> 3.4 PW26 Analytical Results , <br /> Analytical results of groundwater samples collected from monitoring well cluster PW26 <br /> during the fourth quarter 2010 groundwater monitoring event(CRA 2011)are ' <br /> summarized below. Concentrations of EDB have not been detected above the <br /> laboratory reporting limit(0.01, 0.05,or 0.10 pg/L)in well PW26. EDB, DBCP and <br /> Sulfolane analytical results from groundwater samples collected from PW26 during ' <br /> 2010 are summarized on Table 2. Monitoring well cluster PW26 is shown on Figures 3 <br /> through 5. <br /> • Shallow Zone(69-79 feet bgs): DBCP was not detected above the laboratory ' <br /> reporting limit(0.01 pg/L). DBCP has not been detected above the primary <br /> maximum contaminant level (MCL)of 0.2 pg/L(RWQCB 2008)in shallow <br /> zone monitoring well PW26-086. , <br /> Sulfolane was detected at 2,800 pg/L,which is above the health-based <br /> drinking water criterion of 57 pg/L. ' <br /> • Intermediate Zone(137-147 feet bgs): DBCP was detected at 3.2 pg/L,which <br /> is above the MCL of 0.2 pg/L. <br /> Sulfolane was detected at 4,000 pg/L,which is above the health-based ' <br /> drinking water criterion of 57 pg/L. <br /> • Deep Zone(183-193 feet bgs): DBCP was detected at 1.2 pg/L,which is below ' <br /> the MCL of 0.2 pg/L. <br /> Sulfolane was detected at 3,100 pg/L,which is above the health-based ' <br /> drinking water criterion of 57 pg/L. <br /> 3.5 Groundwater Data Gaps. <br /> Additional step-out soil borings are proposed to investigate a potential data gap <br /> laterally and vertically in all directions from borings SB-3a and SB-24a and PW26 to <br /> further delineate sulfolane in groundwater to approximately 90 feet bgs. Proposed ' <br /> boring locations are shown on Figure 5 and summarized on Table 1. <br /> 1 <br /> Wthmp d-s:plan 090211,dcc 6 <br />