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Mr Harlin Knoll Page 3 of 4 located in San Joaquin County and reviewed literature from K-V Associates, Inc , which manufactures the C-Sparger® System According to the literature, C-SpargingTM is in-situ air stripping with mucro-encapsulated ozone First, generated ozone is injected into the subsurface in the form of fine bubbles with a high surface- to-volume ratio The injected ozone bubbles come Into contact with impacted groundwater, where contammants in groundwater volatilize into the ozone bubbles and are oxidized Several studies evaluating the efficacy of ozone injection for in-situ groundwater remediation have shown significant reductions in contamination, however, the effectiveness of the technology appears to be primarily dependent upon hydraulic conductivity of the soil Information from K-V Associates, Inc suggests that soils with hydraulic conductivities less than 10"5 cm/s (fine silts and clays) are not favorable to the technology Of the sites reviewed at the offices of EHD (4707 Pacific Avenue, 437 E Minor, 2701 W March Lane) only one file (437 E Minor) had any information regarding results of ozone injection pilot testing The other sites were in various stages of approvals and installation The results of pilot testing at 437 E Minor suggests that ozone injection shows promise in soil types from coarse sands to sandy silts The soil within the saturated zone in the vicinity of well MW5 generally consists of lean clay from the top of the water table (currently approximately 36 5 feet bgs) to a depth of 50 feet bgs, which is underlain by silty sand (50-59 feet bgs), lean clay (59-65 feet bgs) and well graded sand (65-70 feet • bgs, the maximum depth explored) Soil analytical results and PID readings from borings advanced in the area of the gasoline release suggests that the bulk of contamination resides in lean clay and fine silt between the depths of approximately 33-63 feet bgs Copies of well/bormg logs for DBI IDB l a, DB2, DB3, and MW5 are included in Attachment E Figure 4 shows the locations of these borings SUMMARY AND CONCLUSIONS Groundwater at the site flowed in a northeasterly direction, and the potentiometric surface in site wells fell an average of 4 51 feet between May 21, 2002 and August 16, 2002 The water level lies above the screened interval in wells MW4 and MW5 TPHg and BTEX were not detected in wells MW3 and MW4 Gasoline constituents in well MW5 decreased by 26-80% from the previous quarter, although contaminants increased slightly in well MW The overall contanunant trends at the site are generally decreasing (Attachment C) Based upon results of pilot tests in the liturature, in-situ ozone treatment of petroleum hydrocarbon impacted groundwater can effectively reduce dissolved gasoline constituents at certain UST sites However, the degree of effectiveness appears to be related to the hydraulic conductivity of the soil Based upon known soil types within the zone of contamination at this site, it is unclear if ozone injection would be effective at this site 40 G 1DawGR0UNDZEIKNOWLLS I-IAMIREPORTSIQhAR\3QM2002 doc