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r` BasesEnvironmental Management,Lr, <br /> 1P 002-70950-04 U-Hain#709-50 <br /> 4 Groundwater Monitoring Report <br /> t <br /> 09/09/02 <br /> Groundwater samples collected from the site were contained in appropriate sample bottles supplied <br /> b <br /> Del Mar. Following collection, the groundwater samples were placed on ice and transported, under <br /> proper chain-of-custody record, to Del Mar for analysts. <br /> - 3.2.2 Groundwater Sara le Anal sis--June 2002 <br /> -� The groundwater samples collected in the June 2002 groundwater monitoring event were analyzed for <br /> total petroleum hydrocarbons as diesel (TPHd), and total petroleum hydrocarbons as gasoline (TPHg), <br /> using EPA Method 8015B. The samples were also analyzed for benzene, toluene, ethylbenzene, and total <br /> ► : xylenes (BTEX); methyl tert-butyl ether (MTBE); tert-butanol (TBA); di-isopropyl ether (DIPE); ethyl <br /> tert-butyl ether(ETBE); and tert-amyl methyl ether(TAME), according to EPA Method 8260B, The SJC <br /> 11 ; requested that the groundwater sample collected from MW- <br /> 2C well MW 2C also be analyzed for volatile organic <br /> compounds using EPA Method 8260B full list. <br /> i <br /> Fj i <br /> 3.3 GROUNDWATER ANALYTICAL RESULTS—JUNE 2002 i <br /> k + <br /> Laboratory analytical results of the <br /> June 2002 groundwater sampling event, which included two sample <br /> groups ("B" and "C" casing samples), revealed substantial variation between the two groups. A <br /> Fi, <br /> summary of the analytical results for the June 2002 sampling p g ev ent is presented in Table 2. A copy of � <br /> the corresponding laboratory analytical report and chain-of-custody documentation is provided in <br /> Appendix D. <br /> r <br /> Analytical results of groundwater samples collected from the well casings screened across the <br /> groundwater interface (`B" casings) revealed the highest concentrations of hydrocarbons in groundwater <br /> from wells MW-2B, MW-3B, and MW-4B- The concentrations of hydrocarbons in groundwater from <br /> wells MW-2B and MW-3B were greater than 100,000 micrograms per liter(pg/L)TPHg and greater than <br /> 10,000 µg/L benzene. The detectable concentration of benzene in the sample from well MW-4 was 650 <br /> pg/L. Benzene concentrations below,laboratory reporting limits were found in groundwater samples <br /> from monitor wells MW-IB, MW-5B, MW-8A, and MW 10B. Analytical results are summarized in i <br /> Table 3. The approximate extent of hydrocarbon contamination in groundwater associated with "B" <br /> casing wells is shown in Figures 5 and 6. <br />�I 7 <br /> d <br /> 7 <br />