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5.4 Organic Vapor Monitoring . To obtain preliminary data regarding the degree of potential petroleum hydrocarbon-impact to soil and for health and safety concerns, a representative sample was collected at each soil sampling location and field screened for volatile organic vapors utilizing a hand held photo-ionization detector (PID) in general accordance with ATC's Standard Operating Procedure - Field Soil Vapor Monitoring, which is included in Appendix C PDD readings were recorded in the boring logs ' 5 5 Well Installation Following completion of well borings MW-13 through MW-17, the borings were completed as groundwater monutor wells The construction of MW-13 through MW-17 consisted of 40 feet (surface to 40 feet bgs) of blank 2-inch diameter, Schedule 40 Polyvinyl Chloride (PVC) casing, and 25 feet of slotted (0 020-inch slots) 2- inch diameter Schedule 40 PVC well screen All well casing and screen was delivered to the site in ' factory-sealed containers The annulus of the screened portions of the monitor wells were backfilled with a #3 Monterey sand (or ' equivalent) filter pack from approximately 39 to 65 feet bgs The filter material was then settled by surging the well with a surge block Additional sand was added to the annulus prior to placement of the bentonite sea] if any settlement occurred A 2-foot-layer of bentonite pellets was then placed on top of the upper filter pack and hydrated to form an annular seal Bentonite grout was placed from 37 to 6 feet bgs and neat cement was used to fill the remaining annular space to approximately 2-feet bgs The wells were ' then completed from 2-feet bgs to the ground surface with a watertight, flush-mounted, traffic-rated vault and set in a 2-foot concrete perimeter seal Monitor well construction details are presented in Table 2, Well Construction Details, and are illustrated in Figure 5, Groundwater Monitor Well (MW-13 through ' MW-17) Construction Detail Following completion of well boring EX-1, the boring was completed as groundwater extraction well The ' construction of EX-1 consisted of 40 feet (surface to 40 feet bgs) of blank 6-inch diameter, stainless steel casing, and 30 feet of slotted (0 010-inch slots) 6-inch diameter Schedule 40 PVC well screen All well casing and screen was delivered to the site in factory-sealed containers The annulus of the screened portions of the extraction well was backfilled with a #3 Monterey sand (or equivalent) filter pack from approximately 39 to 70 feet bgs The filter material was then settled by ' surging the well with a surge block Additional sand was added to the annulus prior to placement of the bentonite seal if any settlement occurred A 2-foot layer of bentonite pellets was then placed on top of the upper filter pack and hydrated to form an annular seal Bentonite grout was placed from 37 to 6 feet bgs and neat cement was used to fill the remaining annular space to approximately 2-feet bgs The wells were then completed from 2-feet bgs to the ground surface with a watertight, flush-mounted, traffic-rated vault ' and set in a 2-foot concrete perimeter seal Groundwater extraction well construction details are presented in Table 2, Well Construction Details, and are illustrated in Figure 6, Groundwater Extraction IWell (EX-1) Construction Detail EZ 100966ASAR rpt ATC Associates Inc ' 11San DiegolEZ Serve11009661Reports1100966SAR001 rpt ATC Project Pio 43 25827 0026 8