Laserfiche WebLink
Task 2:Steady-State Sustainable Yield Analysis <br /> • ISWS will conduct steady-state simulations to determine the acceptable long-term <br /> drawdown within the aquifer,assuming the wells are pumped year-round under <br /> average conditions. <br /> • Simulations will test historical steady-state yield estimates of 7.5 million gallons per <br /> day(MGD)against proposed external criteria,such as limiting maximum drawdown <br /> to the top of the Glasford formation. <br /> • Modeling will incorporate specific pumping rates and well configurations <br /> recommended by INTERA,including scenarios targeting a 10 MGD firm capacity <br /> achieved by operating five wells at 1,400 gallons per minute(gpm). <br /> • Scenarios will evaluate allocation of withdrawals across the current DeWitt <br /> wellfield,the newly acquired northwest parcel(assumed to accommodate up to two <br /> wells pumping at 1,400 gpm per well),and the Cisco well. <br /> Task3:Transient Drought Scenario Modeling <br /> • Transient simulations will be developed to assess the aquifer's response under <br /> acute and prolonged drought conditions,specifically modeling continuous <br /> emergency pumping durations of 3 to 6 months. <br /> • A hybrid operational scenario will be simulated wherein the wellfield runs at a low- <br /> level constant rate to meet a base level demand,followed by a sudden increase in <br /> pumpage(up to 10 MGD)triggered by a severe drought event. <br /> • The model will evaluate acceptable drawdown impacts across multiple well <br /> configurations:the current wellfield alone,the current wellfield supplemented by <br /> the northwest parcel,and the inclusion of the Cisco well. <br /> • Special consideration will be given to evaluating the Cisco well to better understand <br /> its hydraulic connection to the Sangamon River. However,given the lack of robust <br /> calibration data to test the model against in this region,it is likely that our certainty <br /> in results relevant to the Cisco well field will be limited.An expected outcome of this <br /> project is the recommendation of a smaller follow-up study that focuses specifically <br /> on the Cisco well and impacts to the Sangamon River.The requested project <br /> timeline will not allow for a thorough investigation during this phase of work. <br /> UNIVERSITY OF ILLINOIS URBANA-CHAMPAIGN <br /> 217.333.2210•isws.illinois.edu <br /> Page 9 of 10 <br /> SPA Form <br />