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, <br /> GSI Field Methods and Procedures <br /> April 28, 1995 <br /> Field Screening of Soil Samples <br /> A PID is used to perform head-space analysis in the field for the presence of organic <br /> vapors from the soil sample. This test procedure involves removing soil from the tip of <br /> the sampling device or sample liner into a clean glass ,lar, and immediately covering the <br /> ,lar with aluminum foil secured under a nng-type threaded lid After approximately twenty <br /> minutes, the foil is pierced and the atmosphere within the jar tested using a PID Head- <br /> space screening results are recorded on the bonng log. Head-space screening procedures <br /> are performed and results recorded as reconnaissance data GSI does not consider field <br /> screening techniques to be verification of the presence or absence of hydrocarbons. <br /> Construction of Monitoring Wells <br /> Monitoring wells are constructed in the exploratory soil borings with Schedule 40 polyvinyl <br /> chloride (PVC) casing. All ,joints are thread-joined, no glues, cements, or solvents are <br /> used in well construction The screened interval is constructed of machine-slotted PVC <br /> well screen which extends from the total well depth to a point above the groundwater. An <br /> appropnately-sized sorted sand is placed in the annular adjacent to the entire screened <br /> interval A bentonite seal is placed in the annular space above the sand, and the remaining <br /> annular space is sealed with neat cement or cement grout <br /> Wellheads are protected with water-resistant traffic-rated vault boxes placed flush with the <br /> ground surface The top of the well casing is sealed with a locking waterproof cap. A <br /> lock is placed on the well cap to prevent vandalism and unintentional introduction of <br /> materials into the well. <br /> Measurement of Water Levels <br /> The top of the newly-installed well casing is surveyed by a California-licensed Land <br /> Surveyor to mean sea level (MSL). Depth-to-groundwater in the well is measured from <br /> the top of the well casing with an electronic water-level indicator Depth-to-groundwater <br /> is measured to the nearest 0.01-foot, and referenced to MSL. <br /> Well Development and Sam lin <br /> The purpose of well development is to improve hydraulic communication between the well <br /> and the surrounding aquifer. Prior to development, each well is monitored for the <br /> presence of floating product and the depth-to-water is recorded Wells are then developed <br /> A-2 GeoStrategies <br />