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The pumping test report also provides a capture zone analysis f o r extraction well EW-I. A capture zone is the area of a aquifer in which all of the groundwater will be removed by a pumping well at a specific pumping rate over period of time. Boundary conditions were n o t considered in this analysis. The following assumptions were made in the capture zone analysis: a sustainable pumping rate (Q) of 7 gpm (1 ,347.5 cubic feet per day), a saturated thickness (B) of 12.58 feet, a hydraulic conductivity (K) of 23.7 ft/day, a potentiometric surface gradient of 0.0105, and an assumed porosity of 0.15. Based on the capture zone analysis, well spacing to capture all water flowing from the site would be 32.3 feet perpendicular to the groundwater flow direction. Groundwater samples were also collected from the extraction well periodically during the pump test. Samples were collected at 7 minutes, 330 minutes, 660 minutes and 995 minutes into the test. These samples were contained in 40-m1 VOA vials, preserved with hydrochloric acid, and sealed without headspace. The samples were then labeled and stored with ice for transport to McCampbell Analytical, Inc. of Pacheco, California (FLAP #1644) under chain of custody. The samples were then analyzed by McCampbell Analytical for TPH-G by modified EPA Method- -5030/8015 , -� BTEX by EPA Method 8020, and the fuel oxygenates MTBE, DIPS, ETBE, TAME and TBA by EPA Method 8260. Analytical results for these samples are tabulated a Table Four. The laboratory analytical report and chain of custody documents are presented in Appendix J. There was n o discernable increasing or decreasing trend in hydrocarbon concentrations during the test. 8 .3 Vapor Extraction Test On September 26, 2001, ASE senior project manager David Allen, in conjunction with personnel. of Environmental Techniques of Huntington Beach, California, conducted a vapor-extraction (VE) test at the site. The test was designed to remove a known rate of soil -as from vapor extraction well VE-1 using a vacuum-blower powered by the power take- off of a 6-cylinder internal combustion engine (ICE), measure vacuum and the amount of air flowing from VE-1, and determine if that vacuum can influence the vadose zone in nearby observation wells. Just prior to the removal of soil gas from well VE-1, observation wells VE-2, MW-2, MW-3, MW-4 and EW-1 were fitted with sealed caps and negative-pressure gauges to record any increase in negative pressure within these wells located at various distances from VE-1 . An initial, background, negative-pressure reading was taken from the five observation wells prior to the beginning of the test. 574 West Grant Line Road CAP — January 2002 -14-