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Blaen Envtronrrrenlal Management Inc 002-70950-03 U-Hau111709-50 Work Plan 1118101 investigation indicated that petroleum hydrocarbons were present in soil at depths of 60 to 75 feet bgs In 1992, subsequent groundwater monitoring performed by ETS indicated concentrations of hydrocarbons above the California action levels in groundwater samples from the three wells (Applied, 1992) In September 1992, Applied Consultants (Applied) began managing the site for U-Haul Quarterly groundwater monitoring conducted in September 1991 indicated that the depth to groundwater across the site ranged from 85 5 to 86 74 feet bgs and the groundwater flow direction was to the north at a gradient less than 0 001 feet/foot Analytical results of groundwater samples indicated that groundwater at two of the three wells contained benzene at concentrations greater than the Califomia action level(Applied, 1992) Applied completed further assessment of hydrocarbons in soil and groundwater in 1993 This work involved drilling and sampling five additional soil borings and the installation of three additional on-site monitoring wells (MW-4, MW-5, and MW-6) The Applied report concluded that the source of hydrocarbons in soil was located near boring B7 Analytical results of soil samples indicated that hydrocarbons were present at 70 and 75 feet bgs, the depth to groundwater at that time Analytical results of groundwater samples indicated that the hydrocarbon plume in groundwater was centered near monitoring well MW-1 Benzene concentrations exceeded the California action level in groundwater samples from each of the six monitoring wells (Applied, 1993) In 1995, SOTA conducted further assessment of groundwater conditions with the installation of one off-site and one on-site groundwater monitoring well These monitoring wells (MW-7 and MW-8) were included in the quarterly monitoring program in October 1995 Results of the October 1995 quarterly monitoring and sampling event indicated that the depth to groundwater was between approximately 63 to 66 feet bgs and the groundwater flow direction was toward the southwest Analytical results indicated that hydrocarbon concentrations exceeded California action Ievels in groundwater samples from five of the seven on-site monitoring wells Results also indicated that elevated hydrocarbon concentrations were present in groundwater from the off-site monitoring well (MW-7) (SOTA, 1995) Between November 1994 and September 1997, SOTA conducted groundwater monitoring at the site During this period, the screen intervals of the on-site monitor wells became submerged(SOTA, 1997) 4