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y 0, Mr Kyle Christie Project 0805-146 03 November 28, 1995 Page 3 Results of this assessment were reported in EMCON's Second Quarter 1995 Status Report (EMCON, August 2, 1995) Results of analyses indicated that TPHG concentrations were below laboratory detection limits in all soil samples analyzed, except for the soil sample collected at 25 feet bgs (in the historical capillary fringe zone in boring B-13, which had a concentration of 6 ppm) Benzene, toluene, ethylbenzene, and total xylenes (BTEX) was detected at low concentrations in soil samples collected from the boxings Benzene concentrations ranged from 0 005 ppm to 0 087 ppm GROUNDWATER MONITORING: THIRD QUARTER 1995 EMCON was contracted by ARCO to monitor the groundwater monitoring wells previously installed at the site Field work included measuring depths to water and collecting groundwater samples for subjective and laboratory analyses EMCON used these data to evaluate the direction and gradient of groundwater flow beneath the site ✓/On August 15, 1995, a technician from EMCON measured depths to water and collected groundwater samples from wells MW-1 through MW-7 for subjective and laboratory analyses Floating product was not noted in samples from the wells (see Table 2) Feld procedures are presented in Appendix A The wellhead elevations of the site monitoring wells were previously surveyed by Tom O Morrow, Inc The surveyed elevations and the depth to groundwater measurements, summarized in Table 2, were used to evaluate the potentiometnc surface beneath the site. The direction of groundwater flow on August 15, 1995, was northeast to southeast with a hydraulic gradient ranging from 0 002 to 0 005, as shown on Figure 3 The gradient generally been toward the northeast Groundwater elevations have increased approximately 0 36 feet since the last sampling event(May 1995) Groundwater samples from wells MW-1, MW-3 through MW-5, and MW-7 were analyzed for TPHG using Environmental Protection Agency (EPA) Methods 5030/DHS LUFT, BTEX using EPA Methods 5030/8020 prescribed by the State of California, and HVOCs using EPA Method 601 In addition, the samples from wells MW-2 and MW-6 were analyzed for TOG using Standard Methods (SM) 5520 C&F and reported as total and nonpolar oil and grease These samples were analyzed at Columbia Analytical Services, Inc , in San Jose, California. The results of analyses are summarized in Tables 1 and 2 Copies of the chain-of-custody records and laboratory analysis reports are presented in Appendix B Results of analyses indicated dissolved gasoline hydrocarbons were detected in samples collected from the six wells Concentrations of TPHG ranged from 20,000 parts per billion (ppb) in well MW-2 to 120,000 ppb in well MW-6, and benzene concentrations ranged SALIN T10\080508051460 9CS-951pas 1