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7m ' S E C O R ' Request for No Further Action . Chevron Station 9-2396 December 16 2004 Page 5 On June 18 and June 24, 2002, SECOR developed and sampled wells MW-1 through ' MW-3 Groundwater samples were submitted for analysis of TPHg, BTEX, and MtBE No hydrocarbon constituents were detected above their method detection limits, with the exception of MtBE in MW-1 (1µglL) and MW-2 (5 pg/L) ' Groundwater Monitoring and Sampling — 2002 to 2004 ' Quarterly monitoring and sampling was initiated after installation of groundwater monitoring wells MW-1 through MW-3 The monitoring wells were surveyed within 0 01-feet relative to mean sea level (MSL) TPHg and BTEX have not been detected above the laboratory ' method detection limits since groundwater monitoring and sampling began (Table 3) In October 2002, MtBE was reported in MW-2 at concentrations ranging up to 7 µg/l_ and in MW-1 at concentrations up to 1 Rg/L Additionally, no detections of hydrocarbon oxygenate ' compounds have been reported above the laboratory method detection limits since groundwater monitoring and sampling began (Table 4) tBased on depth to water measurements during the Second Quarter 2002, groundwater flow direction has been to the south at a gradient of 0 002 Data from the Third Quarter 2004 Groundwater Monitoring Report puts flow direction to the southwest at a gradient of 0 003 10 An overall increase in depth to water of 5 feet between June 18, 2002 and October 8, 2004 is shown graphically in Figure 4 Groundwater flow direction has been variable (Table 5) with an average flow direction to the south Fluctuations in the flow direction are displayed ' on the rose diagram in Figure 5, showing that groundwater flow direction is south-southwest Since monitoring and sampling was initiated, depth to groundwater has ' ranged from 73 38 feet to 79 91 feet below ground surface (bgs) The Third Quarter 2004 Groundwater Monitoring Report is contained in Appendix D ' Once the County grants a closure permit for this site, monitoring of groundwater at the site will not be required and the groundwater monitoring wells MW-1 through MW-3 located on-site will no longer be necessary Therefore, SECOR proposes the destruction of the ' groundwater monitoring wells in accordance with the terms outlined in the Well Destruction Work Plan (Appendix E) ' 3 3 Well Search and Field Survey The site is located north of Collierville in an older part of Acampo Based on a review of ' Department of Water Resources (DWR) files and San Joaquin County Environmental Health Department (EHD) well permits and well drillers reports, most private residences have domestic wells On October 28, 2004 SECOR conducted a door-to-door field search, ' covering a 2,000 foot radius from the site, to verify the status of wells identified by the DWR and EHD file review (Appendix F) The approximate locations of the wells identified in the door-to-door survey are displayed in Figure 6 The data obtained from DWR and EHD I 1Chevron1923961Reports\FINAL_NFAR_REPORT doc