ARCHIVED REPORTS XR0008501 - Laserfiche WebLink

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• drill solids were clearly marked and stored, the drilling crew and Mr Fry left the location at 1730 hours On June 2, MW-2 & MW-3 were developed by MDE personel by swabbing the screened interval with a rubber disk 55 gallons of water was removed from each well, (approximately 7 casing volumes, ) and placed an metal drums for storage on site On June 8 , Del-Tech Geotechnical Support Services purged and sampled as directed by the San Joaquin County PHS, EHD staff; refer to EXHIBIT G for details of that work The wellheads were measured to . 00 ' by a licensed surveyor to allow accurate gradient calculations That data is included as EXHIBIT I DISCUSSION OF RESULTS OF ABOVE WORK Results of the laboratory analyzes of somal samples from MW-2 & MW-3 are summarized on TABLE XI, copies of the reports are included as EXHIBIT F The data shows that minor amounts of ethylbenzene, toluene, & xylene were measured in the soil sample • at 10 ' in MW-2 ; all soil samples taken below 30 ' revealed varying concentrations of BTEX & TPH-G This is in agreement with PID readings taken during drilling operations MW-3 showed a manor amount of xylene in the soil sample from 19 5 ' -201 , but signifi- cant levels of BTEX & TPH-G an all soil samples below that depth. Measured levels of BTEX & TPH-G in MW-3 were higher than in MW-2 , that correlates well with the PID readings, which were also higher in MW-3 A review of the results of the soil sample analyzes from the three monitoring wells, (TABLES VIII & XI, ) reveals that contami- nation was recorded at 24 5 ' bgl an MW-3 , at 29 . 5 ' bgl an MW-2 , and at 36 ' bgl in MW-1 & soil boring #2 . MW-1 & SB-2 are located closest to the removed UST' s, and would be assumed to have soil contamination at shallower depths than MW-2 or MW-3 which are farther from the tank site, and downgradient . However, MW-3 , which is the farthest from the removed tanks, and not directly downgradient, recorded the highest levels of BTEX & TPH-G an soil samples at shallower depths than the other two wells . MW-2 , directly downgradient, recorded lower levels of all contaminants than MW-3 . The reason for this anomaly cannot be readily explained at this time The results of water analyzes from the three wells taken June 8, (refer to TABLE XII, ) reveals the same correlation; MW-1 has the • lowest levels of BTEX & TPH-G, and MW-3 the highest . Again, this 8