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GROUNDWATER MONITORING Groundwater Levels `r On June 18, 1995, Apex personnel collected groundwater-level measurements from all six wells. All groundwater elevations were measured to the nearest 0.01 foot, referenced to the surveyed top-of-casing elevations and conducted according to the Apex standard operating procedures (SOP)included as Attachment 1. Liquid-level measurements collected since January 1993 are summarised in Table 1. Figure 3 is a potentiometric surface map of the shallow water-bearing zone on June 18, 1995. No floating liquid hydrocarbons(FLIT)were observed to be present in any of the wells. .r Groundwater Sampling and Analysis On June 18, 1995, Apex personnel collected groundwater samples from the six wells. The wells -- were sampled for total petroleum hydrocarbons(TPH), as gasoline, TPK as diesel, and benzene, toluene, ethylbenzene and total xylenes(BTEX). All samples were collected according to the Apex SOP included in Attachment 1. The samples were submitted,under chain-of-custody, to Sparger Technology of Sacramento, California, a state-certified analytical laboratory. Analytical results since January 1992 for(TPIT), as gasoline and diesel, and(BTEX) are summarized in Table 2. The laboratory analytical reports and chain-of-custody form are included in Attachment 3. VAPOR EXTRACTION RESULTS On-May 5, 1995, a soil vapor extraction system consisting of an RS.I. SAVE system was installed at the subject site. The vapor extraction system was installed per San Joaquin Valley Unified Air Pollution Control District (SJVUAPCD)Permit conditions. The vapor extraction system consists of an internal combustion engine with catalytic converters mounted on the exhaust. The system was set up such that soil vapors could be extracted from either vapor well VW-1 and/or monitoring well MW-1. The system was started on May 5, 1995, and has been operated continuously since start up. During this reporting period, soil vapor flow to the system -� has varied from 22 cubic feet per minute(CFM) on June 6, 1995,to 10 CFM on July 18, 1995. An air sparge system was installed for use in conjunction with the vapor extraction system The air sparge system consists of a 1 horse power electric motor which powers a 10 CFM oil-less compressor. The compressor was started on May 31, 1995 and operated intermittently through August 30, 1995 at which time it's operation became continuous. 2