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- .. and the depth of the contamination, but screen interval length shall not exceed fifteen (15)feet. Up to three wells can be completed in one borehole as a nested well. TASK 3 GROUNDWATER MONITORING WELL DEVELOPMENT/SAMPLING A. All groundwater monitoring wells shall be developed sufficiently to remove any fines from the well and to permit water flow through the screen section of the well. B. Groundwater levels shall be determined in all wells prior to purging and also prior to sample collection. If a submersible pump is used for the purging,depth to water shall be monitored during the purging and concurrent with the collection of the parameters discussed below. C. Groundwater shall be collected from all the wells for analysis after sufficient groundwater is purged from the well. The parameters of temperature, pH, and conductivity must be measured concurrently with the purging of the wells to indicate when representative groundwater is entering the well. Groundwater shall be sampled in accordance with accepted industry practices and according to PHS/EHD guidelines. TASK 4 LABORATORY ANALYSIS A. Sufficient soil samples must be analyzed in a State Certified laboratory to fully characterize the concentration and distribution of the contaminants in the subsurface. The detection limits used by the laboratory shall be in accordance with those in the LUFT Manual. All soil samples must be analyzed for the following contaminants: -total petroleum hydrocarbons, diesel GC-FID 3550/8015 -total petroleum hydrocarbons, gasoline GC-FID 5030/8015 -benzene,toluene, ethylbenzene, xylene GC-PID 5030/8020 At least one soil sample from each differing ltthological unit must be analyzed for organic carbon content, porosity and bulk density. In addition to the above noted constituents, soil samples from the area of the waste oil tank shall be analyzed for the following: -chlorinated hydrocarbons GC-MS 5030/8240 -cadmium, chromium, lead, zinc, and nickel ICAPorAA 6010or7000 -polychlorinated biphenyls GC-MS 8080 In addition to the above noted constituents, at least two soil samples from the area of the former 500 gallon tanks(tanks#6-8) must also be analyzed for total lead using atomic absorption (7421). The two soil samples should be those showing evidence of contamination, if any. B. Groundwater samples shall be analyzed in a State Certified laboratory fortotal petroleum hydrocarbons as diesel and gasoline, and benzene, toluene, ethylbenzene, and xylene. TASK 6 VAPOR EXTRACTION TESTING A. A vapor extraction test shall be performed on the vapor extraction test wells. Influence should be checked at any nearby monitoring wells, if construction warrants. TASK 7 CORRECTIVE ACTION PLAN PREPARATION A. Prepare a technical report which documents the above noted activities, and analyzes/discusses the data collected. All data shall be presented in tabular form. The concentrations and distribution of contaminants in the subsurface shall be presented in cross-sections showing soil lithology, contaminant concentrations and well locations/construction. Groundwater elevation contours and contaminant isographs shall be included. The report shall also present the results of the vapor extraction feasibility testing conducted at the site, shall present this technology comparativly with other soil and groundwater cleanup technology applicable to the site and shall present a cleanup system design for the site including costs. TASK 8 QUARTERLY STATUS REPORT PREPARATION A. Prepare astatus report which shall include the tabulated depth to water measurements and the analytical results from the sampling of the site wells, gradient and flow direction data, copies of the laboratory report,field notes from the sampling technician, and the current and expected status of the site activities. 3