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rf� <br /> ANALYTICAL METHODS <br /> -i Chemical analysis of the compliance and stockpiled soil samples was performed by SPL, <br /> Houston, Texas using standard test methods of the United States Environmental Protection <br /> Agency (EPA) and the California Department of Health Setvices. The samples were analyzed <br /> for the following constituents: <br /> • Total petroleum hydrocarbons as gasoline (TPH-G) using EPA Methods 5030/8015 <br /> `r (modified) <br /> r.. Benzene, toluene, ethylbenzene, total xylenes (BTEX), and methyl tert butyl ether (MTBE) <br /> using EPA Methods 5030/8020 <br /> 1 <br /> • BTEX, MTBE, di-isopropyl ether (DIPS), tert-amyl methyl ether (TAME),ethyl t-butyl <br /> ether (ETBE), and t-butyl ether (TBA) using EPA Method 8260 <br /> The results of laboratory analysis of soil samples are summarized in Tables 1 and 2, and the <br /> laboratory reports and chain of custody records are presented in Appendix B. <br /> DISCUSSION OF RESULTS <br /> The results of tris groundwater sampling event,based on field observations and laboratory <br /> analysis,are discussed below: <br /> • Depth to groundwater ranged from 5.58 to 8.02 feet below the top of casing,and <br /> r groundwater elevations ranged from 7.94 to 8.02 feet above mean sea level. <br /> Groundwater gradient across the site, as interpreted from the May 1998 monitoring data, <br /> was approximately 0.001 foot per foot in a general southerly direction. <br /> TPH-G was detected in groundwater sample collected from each well analyzed at <br /> concentrations ranging from 1100 to 67000 micrograms per liter (ug/1). <br /> MTBE was detected in each groundwater sample collected at concentrations ranging from <br /> 880 to 110,000 ug/I using EPA Methods 8021 and/or 8260. <br /> �: • BTEX constituents were only detected in the sample collected from MW-3 using EPA <br /> Method 8260 at concentrations of 6 ug/1 benzene,240 ug/1 ethylbenzene,and 380 ug/1 <br /> total xylenes. <br /> _:_� • Analysis of samples for fuel oxygenates by EPA Method 8260 detected only TAME in <br /> MW-2 and MW-3 at concentrations of 470 and 220 ug/l. <br /> Graphs showing TPH-G and MTBE concentrations in samples collected from Monitoring Wells <br /> 1 MW-2 and MW-3 over time are presented below. <br />