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r*N' _16 50AW Environmental Technology Inc procedures were amended and laboratory analysis was carried out at these depths. At these intermediate levels, samples were once again analyzed at 10- feet increments until field screening results indicated otherwise and the above ' described procedure was repeated Additionally soil samples were collected at 1- to 2-foot intervals in the capillary fringe and saturated zone in order to delineate the smear zone beginning at the first encountered capillary fringe depth and/or groundwater level Wells were constructed with a screen interval 425;-fee (from 85 to 60 feet bgs) of 0 020-inch slotted schedule 40 PVC casing, an feet of solid schedule 40 PVC casing from 60-feet bgs to the surface The annular space was backfilled with filter pack material consisting of No. 2 Monterey sand The filter pack was brought up to 58 feet bgs, 2-feet above the screened interval The filter pack material was trernmied into the annular space to prevent bridging Following the placement of the filter pack material and prior to placement of the sanitary seal, the well was surged to ensure that the filter pack level had stabilized Between 58 to 56-feet bgs, hydrated bentonite chips were placed in the annular seal. From 56 to 2-feet bgs, the annular space was sealed with a bentonite slurry. The bentonite serves as a sanitary and hydraulic seal to prevent surface water infiltration into the underlying aquifer A commercially available 12-inch ' diameter steel well box was installed and grouted with cement concrete at the surface A 4-inch diameter locking well cap was placed on the well for security reasons and keys were given to U-Haul personnel for custody As constructed well diagrams are presented in Figure 7. It should be noted that these well construction details meet the State of California Water Resources Board Bulletin 74-81 and 74-90 and LUFT Manual Requirements. The two monitoring wells MW-7 and MW-8, were developed by the drillers, following installation of wells, using mechanical surging techniques The wells were surged until clear water was bailed. The developed water was ' stored in 55 gallons DoT approved drums for later disposal In order to prevent cross contamination between borings and during the drilling operation, the driller (Spectrum Exploration Inc ) steam cleaned all drilling equipment, tools and augers including sampling spoons After steam cleaning, the tools were further washed with soap solution and double rinsed with distilled water. The rinsate was collected by the drillers and temporally stored ' in DOT approved 55-gallon drums The drums will be appropriately disposed in accordance with the regulatory requirements at a later date 4.2 Subsurface Soil Conditions The purpose of the drilling and soil sampling was to (a) evaluate the subsurface lithology, and the presence of soils impacted by petroleum hydrocarbons (b) to ' install groundwater monitoring wells in order to further delineate the lateral extent of groundwater impacted by petroleum hydrocarbons and, (c) investigate potential off-site sources for petroleum hydrocarbons Two soil borings, which were converted to groundwater monitoring wells were drilled. One off-site (MW-7). south of the site, on the south side of N Wilson Way, and one on-site (MW-8) in the western portion of the site (Figure 2) 5