ARCHIVED REPORTS_XR0002926 - Laserfiche WebLink

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r Groundwater monitoring wells were completed by installing 2-inch diameter, flush-threaded, Schedule 40 PVC casing with 0 020-inch factory-slotted screen Approximately 15 feet of screen was placed in the bottom of the boring and extended from approximately 5 feet above to approximately 10 feet below first-encountered groundwater An RMC 2112 sand pack, or equivalent,was placed in the annular space across the entire screened interval, and extended approximately 2 feet above the top of the screen for the well A 2 foot bentonite transition seal was placed atop the sand pack, and a Portland cement seal extended from the bentomte transition seal to the ground surface The Portland cement seal was emplaced by tremae 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 The boring logs show well construction details The groundwater monitoring wells were developed after completion The development procedure for each well consists of pumping or baiting water from the well until the water is visibly clear, the well goes dry, or until a maximum of ten casing volumes have been removed Organic Vapor Procedures Soil samples collected at 5-foot depth intervals during drilling were analyzed in the field for • ionizable organic compounds using a flame-ionization detector(FID) or a photo-ionization detector(PID) with a 10 2 eV lamp The test procedure involved measuring approximately 30 grams from an undisturbed soil sample, placing this subsample in a ZiplockTM-type bag and warming the bag for approximately 20 minutes (in the sun), then the head-space within the container was tested for total organic vapor, measured in parts per million as benzene (ppm, volume/volume) The instrument was calibrated prior to drilling The results of the field testing was noted on the boring logs FID/PID readings are useful for indicating relative levels of contamination, but cannot be used to evaluate hydrocarbon levels with the confidence of laboratory analyses Monitoring Well Sampling Procedures The sampling procedure for each well consists first of measuring the water level and checking for the presence of separate-phase hydrocarbons (SPH), using either an electronic indicator and a clear Teflon® bailer or an oil-water interface probe Wells not containing SPH are then purged of approximately three casing volumes of water(or to dryness)using a centrifugal pump, gas displacement pump, or bailer Equipment used for the current sampling event is noted on the attached field data sheets During purging, temperature, pH, and electrical conductivity are monitored in order to document that these parameters are stable prior to collecting samples After purging, water levels are allowed to partially recover Groundwater samples are collected SacDP4lSACRFPJICOMMOMC—ltingWIfOLSAa, tlP,olcrrtWiscl880-040lAnndo IT CORPORA TION 11/4100