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CLEARWATER <br /> G R O U P I N C <br /> Ertvzranmrnta! sere:ccs <br />' 2.1 Field Activities <br /> The following is a summary of field activities conducted during quarterly groundwater monitoring of eight wells <br /> 1 at the site <br /> - Date sampled March 3, 1999 <br /> o Wells monitored MW-1 through MW-7,and Domestic Well(DW), <br /> Analytes tested TPHg,BTEX, and MTBE <br /> o Analytical methods EPA Methods 8015 (modified)and 8020 <br /> G Laboratory Entech Analytical Labs,Inc ,Sunnyvale,CA(CA FLAP#2224) <br /> All wells were purged prior to collection of groundwater samples Clearwater gauging and well purging data <br /> tsheets are included in Appendix B <br /> 1 2.2 Groundwater Monitoring Results <br /> Results of fourth quartei 1998 groundwater monitoring and sampling aie summarized below <br /> Depth to groundwater Ranged from 15 96 (MW-3) to t7 35 (MW-7) feet below top of casing <br />' - Flow direction/gradient Northeasterly at 0 00016 it/ft <br /> G SPH- wells/thickness No SPH present <br /> 1 o TPHg concentrations < 50 kg/L (MW-3, 4, 5, 6, 7, and DW) <br /> to 12,000 gg/L(MW-1) <br /> e Benzene concentrations < 0 5 µglL (MW-3, 4, 5, 6, 7, and DW) <br /> to 68 µg/L(MW-1) <br /> e MTBE concentrations < 5 0 µg/L(MW-3, 4, 5,6, 7 and DW) to 540 pg/L (MW-2) <br />' The general groundwater flow direction and gradient for this quarter (Figure 3) were similar to conditions <br /> previously observed at the site <br /> The extent of dissolved-phase gasoline contarunation remains well delineated by the existing monitoring well <br /> network (Figure 4) It is noteworthy that contaminant concentrations this quarter are approximately an order of <br />' magnitude less than previous quarters This reduction in contaminant concentrations is likely the direct result of <br /> ongoing active remediation at the site since the beginning of October 1998 <br /> D-107 1Q99 GW&Sys Mon Report 2 April 5. 1999 <br />