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' Historical Background AGE-NC Project No 00-0764 ' Page 2 of 3 ' To mitigate an unauthorized release of petroleum hydrocarbons from the current UST excavationi floor, the scope of work included the excavation of a limited volume of hydrocarbon-impacted soil and collection of soil samples ' Soli was excavated using a backhoe or an excavator Soil was excavated to a depth of one to two feet below the depth of the UST inverts Soil was placed into an excavation soil bin for transportation ' to an appropriate landfill class 1 landfill at Waste Management at Kettleman Hills or class 11 landfill at Forward Landfill at Stockton Excavated soil was field screened for the presence of volatile organic compounds using an OVM,however,due to the release of waste fluids,all waste placed into ' the bms was disposed of at an appropriate landfill Following the excavation and sampling, clean and appropriate backfill was placed into the ' excavation PREVIOUS SITE INVESTIGATION On 23 and 24 October 2001,four soil probe borings(B i through B4)were advanced at the site under EHD oversight Probe borings were advanced in former UST excavation and west, southwest and east of the former UST area to collect soil and grab water samples Probe boring Bl was advanced ' to a total depth of 65 feet below surface grade (bsg) and borings B2 through B4 were advanced to 40 feet bsg Analytical data is presented in the attached tables Locations of the soil probe bonngs are illustrated on Figure 2 of the report ' The most intensely hydrocarbon-impacted soil was encountered in the area of the former USTs (boring B 1), contaminants were not detected in analyzed soil samples collected from borings B2 ' through B4 At boring location Bl,petroleum hydrocarbons were detected in collected soil samples to depths of 30 feet bsg,but generally were not detected in soil samples collected at 40 feet bsg and below The highest hydrocarbon concentrations were encountered at depths between 10 and 20 feet ' bsg Hydrocarbon-impacted ground water was encountered in all four soil borings The highest ' concentration of dissolved hydrocarbons quantified as TPH-g,TPH-d and overall BTEX compounds were present in a water sample collected at 40 feet bsg from boring B1, at the former UST area However, dissolved TPH-g and BTEX concentrations decreased radially northwest,southwest and ' east away from the area of the UST release In addition,dissolved TPH and BTEX were detected at low concentrations in a grab ground water sample collected from 60 feet bsg at boring B 1 Advanced GeoEnvironmental,Inc.