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GR Field Methods and Procedures—Well Installation Page 2 through a hole in the plastic cap or through the wall of the plastic bag Headspace screening results are recorded on the boring log Headspace screening procedures are performed and results recorded as reconnaissance data GR does not consider field screening techniques to be verification of the presence or absence of hydrocarbons Construction of Monitoring Wells Monitoring wells are constructed in the well borings with Schedule 40 polyvinyl chloride (PVC) casing All ,joints are thread-joined, no glues, cements, or solvents are used in well construction The screened interval is constricted of machine-slotted PVC well screen, which generally extends from the total well depth to a point above the groundwater An appropnately sized sorted sand is placed in the annular space adjacent to the entire screened interval A bentonite transition seal is placed in the annular space above the sand, and the remaining annular space is sealed with neat cement or cement grout Wellheads are protected with water-resistant traffic-rated vault boxes placed flush with the ground surface The top of the well casing is sealed with a locking waterproof cap A lock is placed on the well cap to prevent vandalism and unintentional introduction of materials into the well Measurement of Water Levels The top of the newly installed well casing is surveyed by a California-licensed Land Surveyor to mean sea level (MSL) The surveyor also obtains the horizontal coordinates of the well location including GPS longitude and latitude Depth-to-groundwater in the well is measured from the top of the well casing with an electronic water-level indicator Depth-to-groundwater is measured to the nearest 001-foot, and referenced to MSL Well Development and Sampling The purpose of well development is to improve hydraulic communication between the well and the surrounding aquifer Pnor to development, each well is monitored for the presence of floating product and the depth-to-water is recorded Wells are then developed by alternately surging the well with a vented surge block, then purging the well with a pump or bailer to remove accumulated sediments and draw groundwater into the well Development continues until the groundwater parameters (temperature, pH, and conductivity) have stabilized Storing and Sampling of Drill Cuttings Drill cuttings are either drummed, or stockpiled on and covered with plastic sheeting, and samples are collected and analyzed for disposal classification on the basis of one composite sample per 100 cubic yards of soil Drill cuttings samples are composed of four discrete soil samples, each collected from an arbitrary location The four discrete samples are then composited at the laboratory prior to analysis Each discrete drill cuttings sample is collected by removing the upper 3 to 6 inches of soil, and then driving the stainless steel or brass sample tube into the stockpiled material by hand, mallet, or dnve sampler The sample tubes are then covered on both ends with Teflon sheeting, capped, labeled, and • placed in a cooler with blue ice for preservation A cham-of-custody form is initiated in the field and accompanies the selected soil samples to the analytical laboratory