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WE KLEINFELDER
<br /> 1 EXECUTIVE SUMMARY
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<br /> This is a report of Kleinfelder's Third Quarter 2003 groundwater monitoring for the former Disco
<br /> Facility located at 110 North Filbert Street in Stockton, California.
<br /> On July 29, 2003, ten (10) monitoring wells and three (3) piezometers were sounded for depth to
<br /> groundwater. On July 29, 30, 31, and August 1, 2003, the 10 monitoring wells and 3
<br /> piezometers were sampled by Kleinfelder. The monitoring wells sampled were MW-DIS-1,
<br /> MW-DIS-2, MW-DIS-9, MW-DIS-lls, MW-DIS-11d, MW=DIS-12, MW-DIS-13, MW-DIS-
<br /> 14s, MW-DIS-14d and MW-DIS-15. The 3 piezometers sampled were NP-70'. NP-80', and NP-
<br /> 90'. The monitoring wells and piezometers were sampled in accordance with the "Groundwater
<br /> Monitoring Frequency Decision'Tree" developed by-CH2M Hill.
<br /> The depth to groundwater ranged from 43.54 feet below the top of the well casing (MW-DIS-
<br /> I Is) to 53.02 feet below the top of the well casing (MW-DIS-15). Groundwater elevations for
<br /> the monitoring wells ranged from —32.93 feet (MW-DIS-5) to --33.51 feet (MW-DIS-13).
<br /> Groundwater flow direction at the site is estimated to be towards the east/southeast at
<br /> approximately 0.0004 ft./ft. A groundwater mound was noted near MW-11s, MW-11d, and
<br /> MW-14s. This maybe a result of the air and ozone sparging activities directed at these locations.
<br /> The 13 groundwater samples were analyzed for the following: benzene, toluene, ethylbenzene,
<br /> and total xylenes (BTEX), Total Petroleum Hydrocarbon as gasoline (TPH-g), 1;2-
<br /> Dichloroethane (1,2-DCA), 1,2-Dibromoethane (EDB), and Tert-Butyl Alcohol (TBA). Only
<br /> one groundwater sample (MW-DIS-15) was additionally analyzed for all. of the oxygenates Di-
<br /> isopropyl Ether (DIPS), Ethyl t-Butyl Ether (ETBE), Methyl tert-Butyl Ether (MTBE), and tert-
<br /> Amyl Methyl Ether (TAME). MW-DIS-14s was additionally analyzed for MTBE. This was the
<br /> Third groundwater sampling event conducted from MW-DIS-15 since it was installed in
<br /> iFebruary 2003. Additionally, two groundwater samples were collected from MW-DIS-1ls and
<br /> MW-DIS-14s on September 9, 2003 following the start up of the ozone sparging system.
<br /> TPH-g was detected in 5 groundwater samples analyzed from MW-1, MW-2, NPI-70', 80', and
<br /> 90' ranging from 340 }Lg/l to 160,000 µg/l. Similarly, BTEX compounds were detected in the
<br /> same groundwater samples collected ranging from 1.7 µg/1 (Toluene) to 46,000 µg/l (Toluene).
<br /> 1,2-DCA was detected in 7 of the 13 groundwater samples. The detected concentrations ranged
<br /> from 0.51 µ.g/1 (MW-DIS-12) to 3,100 µg/l (NPI-80'). The detected concentration.of 0.51 µg11
<br /> was just above the laboratory reporting limit of 0.50 µg/l. The detected concentrations of 1,2-
<br /> DCA exceeded the Primary Maximum Contaminant Level (PMOL) for 1,2-DCA of 5 µ.g/1 in five
<br /> of the samples (MW-DIS-1, NP1-90', NPI-80', MW-DIS-11s, MW-DIS-15).
<br /> EDB was detected in the groundwater samples collected from NPI-80', and NP1-90' with
<br /> concentrations of 1,200 µg/1 and 90 µg/1 respectively.
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<br /> 12280.MON/ST03R1392 Page I of 14
<br /> 0 2003, Kleinfelder,Inc October 13,2003
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