ARCHIVED REPORTS_2019 - Laserfiche WebLink

Home Browse Search

Forward Landfill Hydraulic Testing Technical Memo • July 03, 2019 EW-2 Step Test Assessment Step testing was conducted on EW-2 on May 2, 2019. The hydrograph for the step test is provided in Attachment A and field data sheets are presented in Attachment B. Manual water level readings for the pumping well and any adjacent wells are summarized in Table 2 and the step testing results are presented in Table 4 and in Figure 3. Step testing was conducted in six steps at rates of 6.0, 15.5, 35.6, 54.5, 80.0 and 83.0 gallons per minute (gpm).The step tests indicated a specific capacity between 1.6 and 4.0 gallons per foot of drawdown (gal/ft drawdown), with the final step at 4.0 gal/ft drawdown (Table 3). The drawdown at a rate of 83 gpm was 21.0 ft(72.5 ft below top of casing [btoc]), which corresponded to a pumping level of approximately 17.1 ft above the top of screen,with a drawdown of approximately 31% of the water column.A pumping rate of approximately 100 gpm could be achieved with drawdown of 24.5 ft, 36%of the water column, the water level approximately 13.6 ft above the top of screen. During the step test,the drawdown-discharge trend between steps was linear and the well and/or aquifer capacity were not stressed at the test pumping rates,with the well and aquifer likely able to produce more water than the current pump capacity, if required. The drawdown trend during step testing of extraction well EW-2 indicates that the potential production rate for this well is in the order of 90 gpm up to 110 gpm. The conveyance line capacity was increased in June 2019 and the production rate was increased to 100 gpm. This rate of 100 gpm is likely optimal for the well, based on the discharge drawdown trends • observed for the well step test. If production rates above 100 gpm were required, this would require additional upgrades to the conveyance line and/or pump capacity and/or well rehabilitation. Review of the drillers log indicates approximately 12 ft out of 28 ft of the screen interval is located adjacent to permeable sand rich materials. Manual water level readings collected from groundwater monitoring wells AMW-7(located approximately 10 ft from EW-2, screened deep), AMW-38S(located 954 ft from EW-2, screened in the shallow zone) and EW-3R(located 1340 ft from EW-2 and screened in the intermediate zone). No wells displayed a significant drawdown response to pumping EW-2 for the duration of the step test though AMW-7 displayed a slight drawdown response(0.01 ft). This indicates a limited hydraulic connection to AMW-7. The pumping duration was relatively short, and it is likely that the cone of depression did not reach AMW- 38S or EW-3R. EW-4 Step Test Assessment Step testing was conducted on EW-4 on May 1, 2019. The hydrograph for the step test is provided in Attachment A and field data sheets are presented in Attachment B. Manual water level readings for the pumping well and any adjacent wells are summarized in Table 2 and the step testing results are presented in Table 5 and in Figure 4. Step testing was conducted in five steps at rates of 12.8, 18.6, 35.5, 43.6, 54.0 and 65.3 gallons per minute(gpm).The step tests indicated a specific capacity between 1.1 and 1.7 gallons per foot of drawdown(gal/ft drawdown), with the final step at 1.6 gal/ft drawdown (Table 3). The drawdown at a rate of 65.3 gpm was 39.9 ft(94.4 ft below top of casing [btoc]), which corresponded • to a pumping level of approximately 1.7 ft below the top of screen,with a drawdown of approximately 60% arcadis com FL Specific Capacity Test Memo 07032019.docx Page: 3/7