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ATC Associates Inc. <br /> Quality Assurance/Quality Control Plan <br /> Revised March 1998 <br /> 9.0 GROUNDWATER MONITORING PROTOCOL <br /> Monitoring of depth to water and free product thickness within wells at the site will be conducted <br /> using an Interface Probe or Conductivity Meter. For consistency, all measurements will be taken <br /> from the north side of the wellhead at the survey mark. To assess potential infiltration of fine- <br /> grained sediments, total well depth will also be sounded. <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 <br /> product 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 <br /> order from the least to most contaminated, if known. Wells containing free product will be <br /> monitored last. Between each well monitoring the equipment will be decontaminated. <br /> W:\Adnnin\She1ls\QAQC-98.D0C <br /> 8 <br />