Preliminary assessment of potential well yields and the potential for artificial recharge of the Elm and Middle James aquifers in the Aberdeen area, South Dakota

Abstract

A complex hydrologic system exists in the glacial drift overlying the bedrock in the Aberdeen, South Dakota, area. The hydrologic system has been subdivided into three aquifers: the Elm, Middle James, and Deep James. These sand-and-gravel outwash aquifers generally are separated from each other by till or other fine-grained sediments. The Elm aquifer is the uppermost and largest of the aquifers and underlies about 204 square miles of the study area. The maximum altitude of the top of the Elm aquifer is 1 ,400 feet and the minimum altitude of the bottom is 1 ,225 feet. The Middle James aquifer underlies about 172 square miles of the study area. The maximum altitude of the top of the Middle James aquifer is 1,250 feet and the minimum altitude of the bottom is 1,150 feet. The lowermost Deep James aquifer was not evaluated. The quality of the water from the Elm and Middle James aquifers varies considerably throughout the study area. The predominant chemical constituents in the water from the aquifers are sodium and sulfate ions; however, calcium, magnesium, bicarbonate, or chloride may dominate locally. The calculated theoretical total well yield from the Elm and Middle James aquifers ranges from a minimum of 64 cubic feet per second, which may be conservative, to a maximum of 640 cubic feet per second. Based on available data, yields of 100 to 150 cubic feet per second probably can be obtained from properly sited and constructed wells. The feasibility of artificially recharging an aquifer, using the technique of water spreading, depends on the geologic and hydraulic characteristics of the aquifer and of the sediments overlying the aquifer through which the recharge water must percolate. The sites suitable for artificial recharge in the study area were defined as those areas where the average aquifer thickness was more than 20 feet and the average thickness of the fine-grained sediments overlying the aquifer was less than 10 feet. Using these criteria, about 14 square miles of the study area are suitable for artificial recharge. Infiltration rates in the study area are estimated to range from 1.3 to 4.3 feet per day. Using an infiltration rate of 2 feet per day, a spreading pond with an area of 0.16 square mile would be required to artificially recharge at a rate of 100 cubic feet per second.