ARCHIVED REPORTS XR0002747 - Laserfiche WebLink

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M) ti for the well A bentonite seal will extend three feet above the sand pack The monitoring well will be completed with neat cement from the bentonite seal to ground surface The well casing will be topped with a locking cap The wellhead will be contained in a watertight and traffic well box The boring logs will show well construction details Groundwater Extraction Well Installation One groundwater extraction well will be constructed by installing a 4-inch diameter, flush- threaded, Schedule 40 PVC casing with 0 020-inch factory-slotted screen in a ten inch diameter borehole The well will be constructed to approximately 50 feet below grade, with approximately 25 feet of screen will be placed in the bottom of the boring An RMC 2112 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 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 approximately two feet below ground surface The Portland cement seal will be 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 Well construction details will be presented on a boring log contained within the final report The well will be completed at ground surface with a traffic-rated vault The wells will be developed after completion The development procedure for each well will consist of surging the well, and then pumping or bailing 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 The newly installed wells will be surveyed by a California State Licensed Surveyor The well casings will be surveyed to the nearest 0 01 feet in elevation to a known benchmark Organic Vapor Procedures Soil samples collected during drilling will be analyzed in the field for ionizable organic compounds using a photo-ionization detector (PID) with a 10 2 eV lamp or a flame ionization detector (FID) The test procedure will involve measuring approximately 30 grams from an undisturbed soil sample, placing this subsample in a sealed container (either a zip-lock bag ora mason far) The container will be warmed for approximately 20 minutes (in the sun), then the head-space within will be tested for total organic vapor, measured in parts per million as benzene (ppm, volume/volume) The instrument will be calibrated prior to drilling using a 100-ppm isobutylene standard (in air) and a sensitivity factor of 55 which relates the photo-ionization potential of benzene to that of isobutylene at 100 ppm The results of the field testing will be noted on the boring logs PID and FID readings are useful for indicating relative levels of contamination,but cannot be used to evaluate hydrocarbon levels with the confidence of laboratory analyses t�