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• • GROUND ZERO ANALYSIS,INC. Quality ControUQuality Assurance Plan be utilized for purgeable and semivolatile hydrocarbons analyses are shown on Table 2. 9.0 GROUNDWATER MONITORING PROTOCOL Monitoring of depth to water and free phase LNAPL (light non-aqueous phase liquids) thickness within wells will be conducted using an interface probe or conductivity meter. For consistency, all measurements will be taken from the north side of the wellhead at the survey mark. To assess potential infiltration of fine grained sediments,total well depth will also be sounded. Thickness of LNAPL on the groundwater surface is calculated by subtracting the depth to product from the depth to water. In addition, water elevations are adjusted for the presence of fuel with the following calculation: (LNAPL Thickness)(specific gravity)+(Water Elevation)=Corrected Water Elevation Newly installed wells will be allowed to stabilize for 24 hours after development prior to free phase thickness determination. An acrylic Surface Sampler will be used for visual inspection of the groundwater in order to note sheen (difficult to detect with the Interface Probe), odors, microbial action and sediments. The sampler is calibrated in inches and centimeters for visual inspection of product thickness. To reduce the potential for cross contamination between wells, the monitoring will take place in order from the least to most contaminated, if known. Well containing free product will be monitored last. Between each well monitoring the equipment will be decontaminated. Water level data collected from the wells will be used to develop a groundwater contour map for the project site. Groundwater flow will be estimated to be perpendicular to equipotential lines drawn on the map. 10.0 WELL DEVELOPMENT PROTOCOL Groundwater monitoring wells will be surged and developed prior to sampling activities. Approximately 10 times the volume of water in the casing will be withdrawn if possible. If the aquifer is slow to recharge, development will continue until recharge is too slow to practically continue. The volume of water produced versus time will be recorded. All purged groundwater will be stored on-site in 55 gallon waste drums unless permission is granted by the appropriate regulatory agency to discharge the water to the ground surface or sanitary sewer. Drummed water will be labeled with the source of the water to help ensure appropriate disposal based on contamination levels. G:\Data\GROUNDZE\QAQC\QAQC.doc 5