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d.. <br /> ATC Associates Inc. <br /> Quality Assurance/Quality Control Plan <br /> Revised March 1998 <br /> Product thickness is calculated by subtracting the depth to product from the depth to water. In <br /> addition, water elevations are adjusted for the presence of fuel with the following calculation: <br /> (Product Thickness) (8) +(Water Elevation) =Corrected Water Elevation <br /> NOTE: The factor of 0.8 accounts for the density difference between water and petroleum <br /> hydrocarbons. <br /> Newly installed wells will be allowed to stabilize for 24 hours after development prior to free product <br /> inspection. <br /> An acrylic Surface Sampler will be used for visual inspection of the groundwater in order to note <br /> sheens (difficult to detect with the Interface Probe), odors, microbial action and sediments. The <br /> sampler is calibrated in inches and centimeters for visual inspection of product thickness. <br /> To reduce the potential for cross contamination between wells, the monitorings will take place in order <br /> from the least to most contaminated, if known. Wells containing free product will be monitored last. <br /> Between each well monitoring the equipment will be decontaminated. <br /> Water level data collected from the wells will be used to develop a groundwater contour map for the <br /> project site. Groundwater flow will be estimated to be perpendicular to equipotential lines drawn on <br /> the map. <br /> W:\Admin\Shells\QAQC-98.DOC <br />