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GSI Field Methods and Procedures <br /> Updated August 19, 1594 <br /> Page 2 <br /> Field Screening of Soil Samples <br /> A PID is used to perform head-space analysis in the field for the presence of <br /> organic vapors from the soil sample This test procedure involves removing soil <br /> from the tip of the sampling device or sample liner into a clean glass jar, and <br /> immediately covering the jar with aluminum foil secured under a ring-type <br /> threaded lid After approximately twenty minutes, the foil is pierced and the <br /> atmosphere within the jar tested using a PID Head-space screening results are <br /> recorded on the boring log Head-space screening procedures are performed and <br /> results recorded as reconnaissance data GSI does not consider field screening <br /> techniques to be verification of the presence or absence of hydrocarbons <br /> Construction of Monitorinq Wells <br /> Monitoring wells are constructed in the exploratory soil borings with Schedule 40 <br /> • polyvinyl chloride (PVC) casing All joints are thread-joined, no glues, cements, <br /> or solvents are used in well construction The screened interval is constructed <br /> of machine-slotted PVC well screen which extends from the total well depth to <br /> a point above the groundwater An appropriately-sized sorted sand is placed in <br /> the annular adjacent to the entire screened interval A bentonite seal is placed <br /> in the annular space above the sand, and the remaining annular space is sealed <br /> with neat cement or cement grout <br /> Wellheads are protected with water-resistant traffic-rated vault boxes placed <br /> flush with the ground surface The top of the well casing is sealed with a locking <br /> waterproof cap A lock is placed on the well cap to prevent vandalism and <br /> unintentional introduction of materials into the well <br /> Measurement of Water Levels <br /> The top of the newly-installed well casing is surveyed by a California-licensed <br /> Land Surveyor to mean sea level (MSL) Depth-to-groundwater in the well is <br /> measured from the top of the well casing with an electronic water-level indicator <br /> Depth-to-groundwater is measured to the nearest 0 01-foot, and referenced to <br /> MSL <br /> GeoStrategies Inc. <br /> m� <br />