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(TPHd), and kerosene. The Rhodes water well was drilled in 1978 to a depth of 80 feet <br /> bgs (boring log included in Appendix B). The Rhodes domestic well is located on a well <br /> search map (Figure 3)with details listed on Table 1. Currently the Rhodes well is <br /> sampled monthly with groundwater samples are analyzed for total petroleum <br /> hydrocarbons as gas (TPHg),benzene, toluene, ethylbenzene, and total xylenes, (BTEX), <br /> and methyl tert butyl ether(MTBE). Subsequent monthly sampling of the Rhodes water <br /> well will include TPHd, TPHmo, and kerosene in the analytical suite. <br /> If concentration of TPHmo, TPHd, and kerosene are reported below laboratory limits <br /> Apex will assume that the TPHmo in CPT-1 and CPT-2 is defined and stationary. Over <br /> the past seven years the Rhodes well water sample has been collected monthly with only <br /> one spuriously reported concentration of MTBE at 64 gg/L back in July of 2002. <br /> Sampling the Rhodes water well for TPHd, TPHmo, and kerosene has been performed <br /> nine times over the last seven years with all reported results below laboratory detection <br /> limits (historical groundwater data included as Table 2). Monthly sampling of the <br /> Rhodes water sample with additional analysis for TPHd, TPHmo, and kerosene will <br /> ensure that the plume continues to be defined to the east and will serve as confirmation <br /> that the heavier hydrocarbons present reported as TPHmo in CPT-1 and CPT-2 are <br /> localized, stationary and pose no threat to sensitive receptors. <br /> If concentrations of TPHmo, TPHd, and kerosene are present in the Rhodes water well, <br /> indicating that the heavier hydrocarbons are slightly mobile,wells within the source area <br /> (VEW-2, VEW-3/MW-8,MW-12, and RW-2)may require over drilling to depths of <br /> approximately 100 feet bgs to define the vertical extent of the reported contamination, <br /> and aid in the active remediation onsite. <br /> REVISED MONITORING WELL INSTALLATION PLAN <br /> Apex proposes to revise the installation plans for MW-15 to drill the monitoring well to a <br /> depth of 100 feet bgs. Placing MW-15 to a depth of 100 feet bgs will allow samples to be <br /> taken at greater depths to provide evidence the plume is defined vertically downgradient <br /> from the source. Sample at greater depths bgs also serve as evidence that the heavier <br /> hydrocarbons (TPHd, TPHmo, and kerosene) are stationary and not migrating offsite. <br /> ATTACHMENTS: <br /> Figure1 .....................................................................................................Site Vicinity Map <br /> Figure2...........................................................................................................Site Plan Map <br /> Figure3......................................................................................................Well Search Map <br /> Table 1 ........................................................................................Sensitive Receptor Details <br /> Table 2 .................................................. Groundwater Analytical Data(CPT-1 and CPT-2) <br /> Table 3 .................................................................. Historical Groundwater Analytical Data <br /> AppendixA.................................................................................................. SJCEHD Letter <br /> Appendix B................................................................Boring Log and Well Drillers Report <br />