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Austin Road Landfill Appendix D Contaminant Plume Characterization Report Aquifer Test Methods maximum measurement interval of 30 minutes. The Trolls were programmed to convert the water level at the start of each recovery and pumping test phase to represent a drawdown of zero at the start of the test and to record changes in water levels relative to this starting datum. Increases in water level in each well were recorded increasing water level values and decreases in water level were recorded as decreasing values. Measurements of the flow rate of each extraction well were taken from instrumentation associated with the ARL groundwater extraction system. Each well was equipped with a control box which included a totalizing flow meter and an instantaneous flow meter. The readings on both meters were recorded in a bound field log book at periodic intervals throughout the test period. The difference in cumulative flows as indicated by a totalizing flow meter was used to calculate the average flow rate between measurements for the extraction well. The pumping rates for each well were controlled by the design and operation of the ARL remediation system. Based on the totalizing flow meter measurements of each well,the average pumping rate for well EW-1 during the Pumping-1 phase was approximately 106 gallons per minute(gpm),and the average pumping rate for well EW-2 during the Pumping-2 phase was 155 gpm. These numbers differ from the average rates reported by the onsite treatment system operator,which are 60 and 170 gpm for wells EW-1 and EW-2,respectively. After the aquifer testing was completed the treatment system operator indicated that the flow meter from well EW-1 was not operating properly. In early and again in mid-May 1998 readings were taken on the flows in wells E -1, -2 and at the treatment system combined flow influent pipe. The results of these measurements confirmed that the flow meter at well -1 was malfunctioning. AfilhL Flow readings from well E -2 were consistent in the May evaluation and also with the aquifer test; it was assumed then that the flow data collected during the aquifer test from well EW-2 were valid and correct. The discharge rate from well EW-1 that occurred during the aquifer test was calculated based on subtracting the May 1998 combined flows at the treatment plant from the flow recorded at well EW-2. This difference in flow(44 and 35.5 gpm)were averaged to obtain an assumed flow at well EW-1 when both wells were pumping(the Recovery-1 and Pumping-2 phases of the test). These rates are significantly lower than pumping rates provided in an earlier report for well EW-1 (EMCON, 1991). Results from well EW-2 showed that it pumped at a rate approximately 15 percent higher rates when well EW-1 was not running;therefore the assumed pumping rate at well EW-1 was also increased by about this amount during the aquifer test phases when well EW-2 was not running. The assumed pumping rates for each phase of the aquifer test are presented below. Test Phase Well Pumping Rate (gpm) Recovery-1 EW-1 40 Recovery-2 EW-2 180.4 Pumping-1 EW-1 46 Pumping-2 EW-2 154.9 CDM Camp Dresser&McKee D-4 W:AREPORTSNSTOCKTOMARLPLUME.98WPPD.WPD CS 010851 City of Scoclaon 1908554006