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I samples. Groundwater will be collected from the 17jeoprobe borehole using a mini-bailer, lowered to the screened interval through the hollow drive tube. Following sampling, the boreholes will be grouted to the surface and no pe anent installation will remain. Groundwater Monitoring Well Instaffatj on The borings will be converted to groundwater mor'toring wells by installing 2-inch diameter, flush-threaded, Schedule 40 PVC casing with 0.02D-inch factory-slotted screen. Approxi- mately 15 to 20 feet of screen will be placed in the bottom of the boring. An RMC 2/12 sand pack, or equivalent, will be placed in the annular space across the entire screened interval, and will extend approximately 2 feet above the top of the screen for the well. A 2 to 3 foot bentonite transition seal will be placed atop the sand pack, and a Portland cement seal will extend from the bentonite transition seal to the ground surface. The Portland cement seal will be emplaced by tremie pipe or through the center of the hollow-stem augers in one continuous operation from the bottom of the interval to be filled to the top. Emplacement of the Portland cement grout specifically shall not be 1ccomplished by "free fall" from the ground surface. The boring logs will show well construction details. I t Groundwater Monitoring Well Developnient The groundwater monitoring wells will be developed after completion. The development procedure for each well will consist of pumping or bailing water from the well until the water is visibly clear, the well goes dry, or until a maxim im of ten casing volumes have been removed. i Organic Vapor Procedures i Soil samples collected at 5-foot depth intervals during drilling will be analyzed in the field for ionizable organic compounds using a flame-io zation detector(FID) or a photo- ionization detector(PID) with a 10.2 eV lamp. The test procedure will involve measuring approximately 30 grams from an undisturbed soil sample, placing this subsample in a clean clear ziplock type bag and sealing the bag. The bag will be warmed for approximately 20 minutes (in the sun), then the head-space within the bag will be tested for total organic y vapor, measured in parts per million as benzene (p m; volume/volume). The instrument will be calibrated prior to drilling using a 100-ppm isob tylene standard (in air) and a sensitivity factor of 55 which relates the photo-ionization poteritial of benzene to that of isobutylene at 100 ppm. The results of the field testing will be noted on the boring logs. PID/FID readings are useful for indicating relative levels of contamin tion, but cannot be used to evaluate hydrocarbon levels with the confidence of laboratoiy analyses. I k 911-007.1 B/WRKPLN B-2 I t �i