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• ATC Associates Inc. A%TC 1117 Lone Palm Avenue, Suite 201 Modesto,California 95351 209-579-2221 fax: 209-579-2225 Protection Agency (EPA) Method 801513; benzene, toluene, ethylbenzene and xylenes (BTEX), methyl tertiary butyl ether (MTBE), tertiary butyl alcohol (TBA), di-isopropyl ether (DIPE); tertiary amyl methyl ether (TAME), ethyl tertiary butyl ether (ETBE), 1,2-dichloroethane (1,2, DCA) and 1,2 dibromoethane (EDB) by EPA Method 8260B. These borings will be completed as 2" ID PVC groundwater monitoring wells with a 20-foot slotted screen interval from approximately 65 fogs to 85 fbgs. The exact depth may vary slightly based on field conditions. See Figure 2 for well completion details. After well development activities have been completed, the groundwater samples will be analyzed for GROs by EPA Method 8015B as well as BTEX, MTBE, TBA, DIPE, TAME, ETBE, 1,2, DCA and EDB by EPA Method 8260B. Five cone penetrometer test (CPT) borings will be advanced to a depth of approximately 150 fbgs. These will be located adjacent to each of the five 85-foot wells. Groundwater samples will 6tl+(uf"�0t be collected_ -approximately every ten feet from the top of water to the base of the boring during �oaje.Wti t advancement. Approximately four to five es-groundwater samples per CPT boring will be tt Ksde-, analyzed for GROs by EPA Method 8015B as well as BTEX, MTBE, TBA, DIPE, TAME, _ ETBE, 1,2, DCA and EDB by EPA Method 8260B. The CPTs will be grouted/ or sealed to :P"MO`6\eVr% surface upon completion of drilling activities. Suo�C)tnef The sixth boring that will be advanced and then converted to a well is proposed near the center of tNw the site. This boring will be advanced using HSA to approximately 125 fbgs or 130 fogs. Soil samples will be taken every five feet to 85 fbgs but not all of the samples will be analyzed. Approximately three soil samples collected above 85 fbgs will be submitted for EPA Method 8015B and EPA Method 8260 laboratory analysis. This sixth well will then be cored in several wly sk deeper intervals, which are approximately as follows: 90 fbgs to 110 fbgs and 115 fbgs to 130 s- fbgs. These core intervals will target known and suspected contaminated intervals at depth. The exact depths will be selected based on field conditions and/or observations. Approximately five core (soil) samples will be submitted for EPA Method 8015B and EPA Method 8260 laboratory analysis. Calderon [22] metals will also be analyzed by EPA Method 6010B; hexavalent chromium will be analyzed by EPA Method 7199; TOC will be analyzed by the Walkley-Black Method; total and effective porosity will be analyzed by API Method RP40; grain size distribution will be analyzed by ASTM D4464M or equivalent; cation ion exchange (CEC) will be analyzed by EPA Method 9081 or equivalent; soil pH will be measured by EPA 9045 or equivalent or by field test kits. The completion method for this 6th well (i.e., with conductor casing, etc.) was described previously in the July 2007 workplan. This well will eventually be completed as a 2-inch ID groundwater monitoring well with a 5-foot screen (Figure 3). The top of the screen will be from approximately 120 fogs to 125 fbgs. The bottom of the screen will be from approximately 125 fbgs to 130 fbgs. The exact screen depth will be based on field conditions but the screen will be five feet. Unless otherwise indicated the specific procedures for field monitoring (OVA/LEL), lithologic logging, advancement, sampling and installation of the wells remains unchanged from the July 2007 workplan, and will continue to be adhered to throughout the duration of the project. S:\Envirmmental\25291u2eports\2007]uly.dm 2