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a <br />� • i i r <br /> include abundant clay and silt fines, 0 010-inch slotted screens maybe used <br /> In order to compensate for the observed historical variations in water levels, the well screens will be <br /> set with approximately 20 feet extending below the water surface, and 10 feet extending above the <br /> water table surface This corresponds to a well construction with casing from 0 to 30 feet bgs, and <br /> screen from 30 feet to 60 feet below surface <br /> An approximately 2-foot thick bentonite seal will be placed on top of the filter pack The remaining <br /> annulus will be grouted with a 3% bentonite/neat cement slurry Each of the wells will be completed <br /> with a steel street cap The well elevations will be surveyed by a licensed surveyor Elevations will <br /> be measured for the ground surface, and the top of casing The center of each well will be positioned <br /> according to latitude and longitude <br /> 2 6 Well Development <br /> No sooner that 48-hours after the last monitoring well is installed, the wells will be developed using <br /> a combination of bailing, swabbing with a surge block, and pumping with a submersible pump Well <br /> development will be performed until each well is relatively free of fines Groundwater elevation <br /> measurements and groundwater samples will be collected no sooner than 48-hours after the last <br /> monitoring well is developed <br /> 2 7 Equipment Decontamination <br /> Equipment decontamination is conducted to minimize the potential for cross contamination between <br /> well locations The following sections describe the methodologies to be followed for decontamination <br /> of drilling and sampling equipment <br /> 2 7 1 Drilling Equipment <br /> Drilling equipment, including augers and tools, or other equipment that may come in contact with <br /> potentially impacted soils or water, will be steam cleaned between each well The steam cleaner will <br /> be capable of generating a working pressure of 2,000 pounds per square inch (psi), a discharge rate of <br /> 5 gallons per minute (gpm), and an operating temperature of 200 1= <br /> An area on-site will be designated as the decontamination area if, possible, a stream cleaner equipped <br /> with self-containment will be used, or a bermed decontamination area will be constructed The <br /> constructed decontamination area will be lined with two layers of 4 mil visqueen to contain rinsate <br /> from steam cleaning operations The steam cleaning area will be designed to allow rinsate from steam <br /> cleaning of drilling equipment to collect onto the visqueen After completion of each boring, drilling <br /> augers will be transported to the steam cleaning area and will be steam cleaned prior to use at the next <br /> . boring Rinsate collected in the bermed area will be collected and disposed of properly <br /> DAMES&MOORE 3 <br />