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' Page 2 <br /> All drive casing, inner sample barrels, inner rods, and tools will be cleaned with <br /> ' a high-pressure, hot water washer between holes Sample barrels will be <br /> washed with trisodium phosphate and double-rinsed with deionized water <br /> between samples collected in the same hole All rinsate from the cleaning will <br /> be contained in 55-g2llon drums at the project site <br /> 1 <br /> GROUNDWATER SAMPLING PROCEDURES <br /> After the targeted water-bearing zone has been penetrated, the sample barrel <br /> and inner rods will be removed from the borehole, and the drive casing will be <br /> ' pulled up approximately three feet to allow groundwater to flow into the <br /> borehole 1-inch-diameter Schedule 40 PVC casing with a five foot section of <br /> 010" slotted well screen may be installed in the borehole to facilitate the <br /> collection of groundwater samples Threaded sections of PVC are lowered into <br /> the borehole inside the drive casing The drive casing is then pulled up to <br /> expose the slotted interval of the PVC_ Groundwater samples may then be <br /> collected from within the PVC casing with a 1-inch-diameter Teflon or stainless <br /> steel bailer until adequate sample volume is obtained <br /> rPIEZOMETER OR SPARGE POINT INSTALLATION <br /> After the boreholes have been advanced below the water table, small-diameter <br /> PVC pipe may be installed in each boring to serve as temporary piezometers, <br /> sparge points, vacuum extraction, or bloventing points for site characterization <br /> ror remcdiation <br /> 1 The well points will be constructed of 314-inch to 1-inch-diameter, Schedule 40 <br /> PVC well casing and well screen inside the Enviro-Core drive casing A PVC <br /> slip cap will be attached to each well at the ground surface Fine-grained sand <br /> will be tremied into the annular space around the PVC up to approximately 1 <br /> foot above the top of the screened interval A two-foot-thick annular seal, <br /> consisting of 118-inch bentonite chips hydrated with deionized water. will be <br /> added to the annular space from the top of the sand pack, and a cement- <br /> ' bentonite grout tremied to the ground surface The upper 5 feet of the <br /> borehole will be enlarged to 60-diameter to provide a 2°-diameter annular seal <br /> ,ner V1dpra doo <br /> r <br />