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4 <br /> samples). Field measurements included pH, temperature, oxidation-reduction potential (Eh), <br /> conductivity (EC), dissolved oxygen (DO), and permanganate at each well. <br /> Baseline concentrations for key pilot study parameters within the pilot study area are <br /> summarized below: <br /> • TCE concentrations in soil ranged from 9.6 to 190 micrograms per kilogram <br /> (pg/kg)• <br /> • TCE concentrations in groundwater ranged from 30 to 500 micrograms per liter <br /> (pg/L). <br /> • Chloride (CI) concentrations in groundwater ranged from 33 to 140 milligrams per <br /> liter (mg/L). <br /> ■ TDS concentrations ranged from 269 to 852 mg/L. <br /> 3.1 Vertical Profile Sampling at M-25C1 <br /> Soil samples collected by CPT in October 1998 were used to characterize the vertical <br /> distribution of VOCs in soi15. Background soil samples collected during the installation of <br /> monitoring well M-25C1 were used to characterize pre-injection conditions for metals, <br /> chemical oxygen demand (COD), and total organic carbon (TOC)6. <br /> 3.2 Aquifer Permeability Testing <br /> Nestle was required to monitor aquifer transmissivity and permeability as part of the WPD <br /> requirements. The RWQCB was concerned with potential changes to the aquifer which <br /> might occur due to manganese dioxide (Mn02) precipitation from the permanganate <br /> injection. <br /> Prior to injection of permanganate, rising head and falling head slug tests were conducted <br /> at five monitoring wells (EU-1, EE-1, ED-1, ED-2, and M-1 A) within the pilot study area on <br /> May 15, 1999. These results were used as an indication of background transmissivity in <br /> the Upper Aquifer. On December 23, 1999, approximately four months after the <br /> permanganate injection, IT completed another set of rising and falling head slug tests. IT <br /> analyzed the water level data from these slug tests and found no indication of any impact <br /> to the aquifer permeability. <br /> 3.3 Pilot Study TCE Monitoring Results <br /> The permanganate was not detected more than 20 feet from the injection points over a <br /> timeframe of 6 months following initial injection activities. Hydraulic mixing was enhanced <br /> at various times following the initial injection of permanganate through the pumping of <br /> groundwater from wells EW-1, M-1A, and ED-2. The timing of these mixing activities and <br /> analytical results associated with samples collected from these wells are detailed in the <br /> table below. <br /> TCE oxidation is evidenced by higher oxidation reduction potential (measured as Eh) <br /> readings and lower TCE concentrations. The summary table below shows that 8 of the 21 <br /> samples analyzed with Eh measurements greater than 560 millivolts (mV) had little to no <br /> detectable TCE (less than 15 pg/L), and the four highest Eh measurements (greater than <br />