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Pilot Testing Report and Conceptual Corrective Action Plan .July 15, 1994 Manna Pro, 4004 South EI Dorado, Stockton, CA 30 ' The migration of dissolved-phase BTEX and TPH follows the general direction of the groundwater gradient t - 335 pounds of TPH are estimated to be dissolved in the groundwater at the site 31,134 pounds of TPH are estimated to be adsorbed to the soil on site - A groundwater pumping test was conducted from October 19 through 22, 1993 The pumping test continued for 3 days and provided essential details for estimating groundwater flow and design criteria for hydrocarbon recovery systems - The pumping test was conducted at a 5-inch-diameter extraction well (EW-1) at a flow rate of 1 3 gpm The drawdown monitored at this recovery well was 5 3 feet ' after 4,500 minutes of continuous pumping A distance-drawdown graph and computer model was used to estimate aquifer transmissivity ' The estimated average aquifer hydraulic conductivity, as determined from the pumping test, is 74 gpd/ft2 The average transmissivity was estimated as 738 gpd/ft The average storativity was estimated as 0 007 ' - The velocity of groundwater, using the estimated average aquifer hydraulic conductivity, groundwater gradient, and an assumed effective porosity of 26 percent, is 0 15 foot/day • The steady state groundwater capture zone of well EW-1, while pumping at 13 gpm, was determined to be 635 feet in width with a stagnation point 101 feet downgradient from well EW-1 • Hydraulic control around the impacted area can be achieved with a relatively low pumping rate from three groundwater recovery wells • The physical investigation concluded that the site geology is suitable to treatment by groundwater extraction and HVE • The groundwater capture zone of well EW-1 during combined HVE and groundwater pumping is expected to be enhanced because of greater potential pumping rates and drawdown as was observed during the pilot studies ' • Based on the Vent-ROI computer model, the HVE data analyses determined a radius of influence of approximately 18 feet at 15 scfm at 148 5 inches of water vacuum per extraction well The groundwater pumping test and subsequent computer modeling determined that a combined one-year capture zone of approximately 460 by 360 feet can be ' obtained from three extraction wells depending on the pumping rate of 2 2 gpm per well - Initial concentrations of hydrocarbons in the soil vapor was up to 280,000 JA g/I groundwater pumping and HVE test ' 2819Ra34 070 GROUNDWATER TECHNOLOGY, INC