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June 1996 - 8- 953-7001002 4 SUMMARY AND CONCLUSIONS On the basis of reports reviewed and referenced in this report we conclude that 1 1 The sources of petroleum hydrocarbons at the site were removed and remediated The primary source(s) of the petroleum hydrocarbons at the Union Ice Facility at 1320 W Weber Avenue was (were) removed when four underground fuel storage tanks were removed in 1988 Petroleum hydrocarbons were detected in soil underlying the tanks and in soil within the zone of shallow groundwater fluctuations (approximately 7 to 13 feet bgs) TPH-containing soil was removed in the area of the former underground tanks by excavation of over 4000 cubic yards of soil (an estimated 2000 yards contained petroleum hydrocarbons) The excavation was performed in three stages for a total area of approximately 12,600 square feet and the depths of excavation ranged from approximately 12 to 15 feet below ground surface 2 The extent of petroleum hydrocarbons in soil and groundwater was assessed The extent of petroleum hydrocarbons released at the site was assessed by drilling of 1 boreholes and installation of twelve shallow and two deep (approximately 60 feet) groundwater monitoring wells 3 Groundwater quality at the was assessed by sampling of monitoring wells over a five- year period (1990 to 1995) and little or no adverse affects were found Groundwater quality does not appear to have been adversely impacted by petroleum hydrocarbons released at the site A shallow and deep well were installed immediately adjacent to the former tanks and additional wells were installed hydraulically up-, cross- and downgradient of the former UST area TPHg and BTEX have been intermittently detected in groundwater samples from monitoring wells at the site But in the worst case (MW-4S)petroleum hydrocarbons were detected in two of thirteen samples from this well In the few instances where concentrations of toluene, ethyl benzenes and xylenes were reported,the concentrations were below MCLS for drinking water In one instance benzene was reported at a concentration of 0 003 mg/L,slightly exceeding the MCL of 0 001 mg/L In all other samples benzene was not detected or was below MCLS 4 Beneficial Use of Shallow Groundwater Shallow groundwater beneath the site is not currently used nor is it expected to be suitable for beneficial use Because of the depth of the shallow groundwater,wells cannot be screened in the shallow groundwater and meet the well seal requirements of the State of California for industrial or domestic use In addition, the quality of groundwater is unlikely to be suitable for use because of the presence of bacteria (coliform was detected in one of approximately four groundwater samples analyzed) and other water quality parameters There are no reported water supply wells within 2000 feet of the subject site 9537001 MI(713M) Golder Associates