SITE INFORMATION AND CORRESPONDENCE

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Quality Assurance/Quality Control Plan Page 6 8.0 LABORATORY QA/QC PLAN Soil and groundwater samples will be submitted to a State Certified Hazardous Waste Laboratory for chemical analysis of hazardous constituents. Established QA/QC procedures for analytical operations will include sample custody procedures, standards of analytical accuracy, analysis of matrix spikes and method data, and maintenance of control charts to monitor analytical performance. These QA/QC procedures are outlined in the laboratory QA/QC Plan which is available upon request. Organic chemical analyses will be performed in conformance with standard procedures established by the United States Environmental Protection Agency (EPA) in "Guidelines Establishing Test Procedures for the Analysis of Pollutants Under the Clean Water Act" (40 CFR Part 136, October 1984). The laboratory is periodically evaluated through external performance audits conducted by EPA and DHS using QC labs. The specific analytical methods to 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.