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Second Quarter 1999 Groundvrater Monitoring Report Colberg Boat Works,401 North Stockton Street, Stock--ton,California Page 3 the submittal of a work plan by June 30, 1999 to further define the horizontal extent of the contamination at the former gasoline UST GROUNDWATER MONITORING Groundwater Levels On April 22, 1999, Apex personnel collected groundwater-level measurements from the three groundwater monitoring wells in accordance to the Apex Standard Operating Procedures (SOP) included as Appendix A All groundwater elevations were measured to the nearest 0 01 foot, referenced to the surveyed top-of-casing elevations Groundwater level measurements are summarized in Table 1 A potentiometric surface snap of the shallow water-bearing zone on April 22, 1999 is shown on Figure 3 Groundwater Sampling and Anal sis On April 22, 1999, Apex personnel collected groundwater samples from monitoring wells MW-I through MW-3 in accordance to the Apex SOP included as Appendix A No samples were taken from groundwater monitoring wells MW-4 through MW-b due to the previous closure request Also, analysis for concentrations of TPHd and concentrations of oxygenate constituents, with the exception of MTBE have been discontinued for groundwater monitoring wells MW-1, MW-2 and MW-3 The samples were submitted, under chain-of-custody documentation, to California Laboratory Services of Rancho Cordova, California, a state-certified analytical laboratory The samples were analyzed for concentrations of total petroleum hydrocarbons, as gasoline (TPHg)by EPA Method 8015 Modified and benzene, toluene, ethylbenzene, total xylenes (BTEX) and methyl t-butyl ether (MTBE) by EPA Method 8020 The analytical results are summarized in Table 2 The laboratory analytical reports and chain-of-custody form are included in Appendix B Figure 4 shows the distributions of TPHg, benzene and MTBE in the shallow groundwater on April 22, 1999 at the subject site ' RECOMMENDATIONS In accordance with the directive issued by SJCEHD, Apex is preparing a workplan, which will fully define the extent of petroleum hydrocarbons in the former gasoline UST area This workplan will be submitted b une 30 1999 Upon approval of this workplan by SJCEHD and pre-approval of the costs by the UST Cleanup Fund, the investigation will commence Depending on the results of the investigation, a new closure request may be made for this site IBJ D 1000001-COLBERG BOAT WORKS\QMR04991QMRTEX'T DOC