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Groundwater Monitoring Protocol Monitoring depth to water and free product thickness within wells at the site will be conducted using an Interface Probe and Surface Sampler. The Interface Probe is a hand held, battery operated device for measuring depth to petroleum product and depth to water as measured from an established datum ( i.e. , top of the well casing which has been surveyed) . 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. Product thickness 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: (Product Thickness ) ( . 8 )+(Water Elevation) = Corrected Water Elevation Note: The factor of 0. 8 accounts for the density difference between water and petroleum hydrocarbons. Newly installed wells will be allowed to stabilize for 24 hours after development prior to free product inspection. An acrylic Surface Sampler will be used for visual inspection of the groundwater in order to note sheens (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 monitorings will take place in order from the least to most contaminated. Wells containing free product will be monitored last . Between each monitoring the equipment will be decontaminated. Water level data collected from the wells will be used to develop a groundwater equipotential contour map for the project site. Groundwater flow will be estimated to be perpendicular to equipotential lines drawn on the map.