R2023-227 Resolution Authorizing Farmland Real Estate Purchase in Dewitt County Pursuant to the Water Consultant's Recommendations (Intera)

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aquifer. However, some shallow wells or wells with high pump settings in the area may be negatively affected. Available drawdown in the pumped well does not appear to be a limiting criterion. In general, drawdown in a Dewitt well is expected to be only 10-20 feet larger than the surrounding drawdown in the wellfield. The current static level in the DeWitt wellfield is approximately 100 feet above the top of the Mahomet aquifer. a Rotating production in individual wells in the DeWitt wellfield is not expected to increase safe yield oi• the operating capacity of the wellfield. It is recommended that pumpage be distributed. One alternative LGI considered is to place additional wells in the Cisco area. Two additional wells could be designed to increase the capacity of the Cisco wellfield to 6 MGD. The projected cost of these wells would be approximately $130,000 per well. Pumpage would then be distributed between the DeWitt and Cisco wellfields. Distributing the pumping in this manner would allow more water to be pumped for longer periods of time. If economically feasible, and drawdowns are acceptable, development west of the DeWitt wellfield can also be considered. > The probable maximura safe yield for combined withdrawals from the DeWitt and Cisco wellfields is between 2.55 and 3.10 billion gallons on an annual basis. This is the total annual withdrawal from the aquifer, and is not dependent on the pumping duration. Therefore, the wellfields may be pumped at any rate, but it is recommended that the total amount of water withdrawn from the aquifer does not.exceed these limits. i During the 30 day pumping test, it was determined that the current discharge system is one of the major limiting factors at the current DeWitt wellfield. The existing system will not allow 24 MGD to be discharged to the settling basin. In addition, previous studies have indicated that having the discharge flow to the Sangamon River through Friends Creek allows a large amount of water to soak back into the ground. This reduces the amount of pumped water that actually reaches the treatment plant. Therefore, to minimize losses due to seepage into the ground and to make the wellfield as efficient as possible, a pipeline to the treatment plant should be considered. The size and location of the pipeline should be determined according to the planned use of the wellfield (i.e. a pipeline extending from the DeWitt wellfield joining a pipeline from the Cisco wellfield to the plant, or a pipeline just from the DeWitt wellfield to the plant) The groundwater model can be utilized in the future in various ways to manage groundwater resources in the area on an as-needed basis. For example, the safe operating capacities for non-annual periods of operation can also be determined by the model. Scenarios can be run to simulate 70