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' BtaeS E7rvt�oivaeual M[rnagement !nc 002 7095004 U-Haul#709 50 Groundwater Monttonng Report 1123/03 Prior to. sample collection, the depth to groundwater was measured to confirm that the groundwater level ' had recovered to within 90% of its original level The water level measurements, sample name, time, and container type were recorded on sample data sheets included to Appendix A Groundwater sampling ' procedures are described in Appendix B Groundwater samples collected from the site were contained in appropriate sample bottles supplied by Del Mar Following collection, the groundwater samples were ' placed on ice and transported, under proper chain-of-custody protocol, to Del Mar for analysis 3 2 2 Groundwater Sample Analysis—December 2002 The groundwater samples collected during the December 2002oundwater gr' monitoring event were analyzed for total petroleum hydrocarbons as diesel (TPHd), and total petroleum hydrocarbons as gasoline (TPHg), using U S Environmental Protection Agency (EPA)Method 8015B The samples were ' also analyzed for benzene, toluene, ethylbenzene, and total xylenes (BTEX), methyl tert-butyl ether (MTBE), tert-butanol (TBA), di-isopropyl ether (DIPE), ethyl tert-butyl ether (ETBE), and tert-amyl ' methyl ether (TAME), according to EPA Method 8260B The SJCEHD requested that the groundwater samples collected from wells MW-213 and MW-2C also be analyzed for volatile organic compounds using EPA Method 8260B full list 3 3 GROUNDWATER ANALYTICAL RESULTS—DECEMBER 2002 ' Laboratory analytical results for the December 2002 groundwater sampling p g event which included two sample groups ("B" and "C" casing samples), revealed substantial variation between the two groups A summary of the analytical results for the December 2002 sampling event is presented in Table 2 A copy ' of the corresponding laboratory analytical report and chain-of-custody documentation is provided in Appendix C Analytical results of groundwater samples collected from the well casings screened across the groundwater interface ("B" casings) revealed the highest concentrations of hydrocarbons in groundwater ' from wells MW-2B, MW-3B, and MW-4B The concentrations of hydrocarbons in groundwater from well MW-3B was greater than 100,000 micrograms per liter (ppb) TPHg and greater than 10,000 ppb ' benzene Benzene concentrations were below laboratory reporting limits in groundwater samples from monitor wells MW-5B, MW-8A and MW IOB Analytical results are summarized in Table 3 7