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_ y <br /> ATC Associates Inc! <br /> Quality Assurance/Quality Control Plan <br /> Revised November 2002 <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 <br /> taken from the;`north side of the wellhead at the survey mark. To assess potential infiltration of <br /> fine-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 monitoringthe equipment will be decontaminated. <br /> w:\admin\shells\qaqc-02.doc <br /> 8 <br />