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The gas probe wells were constructed by installing each section of <br /> slotted PVC screen in a high-permeability gravel pack separated by <br /> intervals of low-permeability bentonite. First, gravel was placed <br /> in the bottom of each boring to serve as the base for the deep gas <br /> probe. After the deep probe was installed, the annular space <br /> surrounding the screened interval was filled with 1/4-inch gravel. <br /> A 5-foot-thick seal of granular bentonite was poured over the <br /> gravel pack and hydrated with clean water. The intermediate level <br /> gas probe was then installed above the bentonite seal, and the well <br /> construction procedure was repeated. When the gravel pack for the <br /> shallow gas probe was completed, a bentonite seal was placed up to <br /> the ground surface. Six-inch-diameter locking steel casings were <br /> installed in concrete . at the surface to house and protect the gas <br /> probes. The steel casings were painted orange so they would be <br /> visible to site operating personnel. <br /> Each monitoring well is shown on sheet 3 along with surface <br /> elevations at each wellhead. <br /> Landfill gas monitoring wells will be monitored on a quarterly <br /> basis. Monitoring results will be presented in the form of a <br /> report to the LEA and the Board within 90 days of the sampling <br /> event. The report will include the following items: <br /> 1) The documentation of date, time, barometric pressure, <br /> general weather conditions, atmospheric temperatures, and <br /> probe pressures. <br /> 2) The names of sampling personnel, apparatus used, and a <br /> description of the methods used. <br /> 3) A numbering system to correlate monitoring results to a <br /> corresponding probe location. <br /> Initial monitoring of the wells has shown that concentration of <br /> methane in the air exceeds 5% by volume around the perimeter of the <br /> landfill. Therefore, a gas control system will be installed at the <br /> site. The control system will be installed after the construction <br /> of the clay cap. Specifics of the gas control system will be <br /> submitted when they become available. <br /> The labor camp structures adjacent to the landfill as well as on <br /> site structures will be monitored for methane quarterly. Results <br /> of the structure monitoring will be included in the quarterly gas <br /> monitoring reports. <br /> AIA <br /> or 15 <br />