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4 <br /> the test interval and at 101 feet bgs to prevent short-circuiting of the injection fluid <br /> through the well filter pack. No packers were deemed used for well M-113 based on <br /> screen interval and depth to water during the PPT. <br /> Geomatrix prepared the injection solution on site in a plastic tank using approximately <br /> 400 gallons of treated effluent water from the Industrial Avenue treatment system, 95 <br /> gallons of municipal (tap) water for dilution of molasses, 5 gallons of molasses, and 487 <br /> grams of sodium bromide (NaBr). Three samples of the injection solution were collected <br /> during the "push" phase of the test and analyzed for total organic carbon (TOC) and <br /> bromide. The average concentration of the injection fluid was 5.2 g/L carbohydrate as <br /> TOC and 197 mg/L bromide. <br /> Approximately 255 gallons (WA) and 225 gallons (M-113) of the injection fluid were <br /> delivered to the test intervals on October 4, 2005. The volume of the test solution <br /> represents the volume of water required to penetrate into the pore spaces of the aquifer <br /> a radial distance of 3 feet beyond the well at the test depth. Approximately one casing <br /> volume of municipal water was injected into well WA after the injection fluid to flush the <br /> well and prevent fouling of the dedicated downhole equipment. <br /> After a one-day lag period (October 5, 2005), the extraction phase of the test <br /> commenced on October 6, 2005 and lasted until November 2, 2005. Approximately 138 <br /> gallons (WA) and 125 gallons (M-1B) were extracted during each sampling event prior <br /> to collection of groundwater samples. A total of approximately 1,280 gallons (WA) and <br /> 1,120 gallons (M-113) were extracted over the course of nine extraction and sampling <br /> events. <br /> 3 CARBOHYDRATE INJECTION STUDY MONITORING AND DATA ANALYSIS <br /> The following sections summarize the laboratory results and subsequent data analysis <br /> from the PPTs. <br /> 3.1 Post-Injection Concentration Trends <br /> Post-injection concentrations of TOC and bromide decreased rapidly in groundwater <br /> samples collected from WA, These trends are suggest that the higher groundwater <br /> velocity in well WA (3.9 feet per day measured by tracer dilution testing; Geomatrix, <br /> 2006), caused rapid advection of the injected solution away from the test well. . <br /> Reducing conditions also were not sustained in the vicinity of this well, based on ORP <br /> measurements over time. Concentrations of chemicals of concern (COCs, including <br /> TCE, cis-1,2-DCE, and VC) did not change appreciably in WA during this test (Table <br /> A.2-1). <br /> The groundwater velocity in well M-1 B was slower (1.3 feet per day), allowing for the <br /> injection solution to remain in the vicinity of the well and creating reducing conditions that <br /> were sustained for a longer period of time. <br /> Analytical results for groundwater samples indicated concentrations of nitrate decreased, <br /> while concentrations of iron, manganese, and trace metals were initially higher after <br /> injection (Table A.2-2). The depletion of the electron acceptor (nitrate), and the increase <br /> in the concentration of reduced electron acceptors (iron and manganese) indicate that <br /> reducing conditions were enhanced in the subsurface. The concentration of total <br /> alkalinity also increased in samples from both wells, suggesting that some mineralization <br /> of carbohydrate and an increase in microbial activity occurred as a result of the test. <br /> Concentrations of COCs in groundwater samples collected at the end of the test (22 <br /> days after injection) from well M-1 B and during post-test sampling show that TCE <br />