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Mr Kyle Christie Project 0805-146 03 August 2, 1995 Page 4 Results of analyses indicated TPHG concentrations were below laboratory detection limits in all soil samples analyzed, except for the soil sample collected at 25 feet bgs (m the historical capillary fringe zone ) in boring B-13, which had a concentration of 6 ppm. ' BTEX was detected at low concentrations (from 0 005 to 0 087 ppm) in soil samples collected from the borings Results of analyses are shown in Table 1 GROUNDWATER MONITORING: SECOND 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 May 17, 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) Due to the location of the stockpiled soil, well MW-2 was inaccessible during the site visit. Feld procedures are presented in Attachment 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 potentnometric surface beneath the site The direction of groundwater flow on May 17, 1995, was northeast with a hydraulic ' gradient of 0 002, as shown on Figure 3 The gradient has generally been toward the northeast Groundwater elevations have increased approximately 4 96 feet since the last ' sampling event(February 1995) Groundwater samples from wells MW-1 and MW-3 through MW-7 were analyzed for TPHG using EPA Methods 5030/DHS LUFT, and BTEX using EPA Methods 5030/8020 prescribed by the State of California. In addition, the sample from well MW-6 was analyzed for TOG using Standard Methods (SM) 5520 C&F These samples were ' analyzed at CAS in San Jose, California The results of analyses are summarized in Tables 2 and 3 Copies of the chain-of-custody records and laboratory analysis reports are presented in Attachment C. ' Results of analyses indicated dissolved gasoline hydrocarbons were detected in samples collected from the six wells Concentrations of TPHG ranged from 38,000 parts per billion (ppb) in well MW-1 to 130,000 ppb in well MW-6, and benzene concentrations ranged from 2,300 ppb m well MW-7 to 13,000 ppb m well MW-3 TOG was detected in well MW-6 located offsite and upgradnent at concentrations of 27,000 ppb (see Table 3) Based on a meeting between SJCPHS and EMCON in May 1995, SJCPHS requested that SAON 1P7010805108051450 3BL-951pas 3