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26 May 1998 <br /> AGE-NC Project No 96-0266 <br /> Page 2 of 9 <br /> 2 2 2 _WEST UST AREA <br /> 1 <br /> One 550-gallon gasoline UST was removed from the City of Stockton right-of-way(San Jose Street) <br /> ' in May 1986 Total volatile hydrocarbons (TVH) and volatile aromatics (benzene, toluene, <br /> ethylbenzene and xylenes BTE&X) were detected at concentrations as high as 2,000 parts per <br /> 'million (ppm) in a single soil sample collected from the UST excavation A letter from the PHS- <br /> ' EHD, dated 07 March 1996, indicated that further investigation related to the former UST would be <br /> required before site closure could be issued <br /> i23 GROUND WATER DEPTH AND FLOW DIRECTION <br /> ' The estimated depth to ground water at the site is approximately 10 to 15 feet below surface grade <br /> (bsg) based on the map titled Lines of Equal Depth of Water Wells, Fall 1993 published by the San <br /> ' Joaquin County Flood Control District and Water Conservation District, and information obtained <br /> from the PHS-EHD in monitoring wells at surrounding sites Furthermore, PHS-EHD records <br /> indicate that the highest observed ground water elevation at the property was 10 feet bsg as measured <br /> lie <br /> in 1986 <br /> The prevailing ground water flow direction in central Stockton is generally toward the northeast, <br /> ' however, localized ground water flow direction may vary during winter/summer cycles and tidal <br /> fluctuations Ground water is considered to be of beneficial use and is utilized for domestic, <br /> industrial and commeicial purposes <br /> 3.0 PROCEDURES <br /> ' 3 1 EAST UST INVESTIGATION <br /> 3 1 1 PROBING AND SAMPLING <br /> On 01 and 05 December 1997, a total of twelve soil probe borings (P15b through P25) were <br /> advanced at the site, under the supervision of the PHS-EHD Soil probe borings were advanced in <br /> the vicinity the East UST area located within Lindsay Street, near Buildings B and H Locations of <br /> ' the soil probe borings are illustrated on Figure 2 <br /> All probe borings were advanced using AGE's van-mounted Geoprobe 5400 probing machine Probe <br /> ' borings PI 5, P 17, P 18, P 19, P23, P24a and P25 were advanced to depths of 15 feet bsg Probe <br /> . borings P16, P21 and P22 were advanced to depths of 20 feet bsg Probe boring P20 was advanced <br /> to depths of 25 feet bsg and probe boring P24b was advanced to depths of 35 feet bsg for a water <br />