Description of Equus Beds Recharge Demonstration Project

The water supply for the city of Wichita in south-central Kansas currently comes from two primary sources--the Wichita well field in northern Sedgwick and southwestern Harvey Counties and Cheney Reservoir in southeastern Reno County. These sources will not be adequate to meet the projected city water needs in the 21st century. Artificially recharging the Equus Beds aquifer, which underlies the city well field, is one alternative being considered to meet future demands for water. The primary purpose of the Equus Beds Groundwater Recharge Demonstration Project, which began in 1995, is to evaluate aritificial recharge techniques from two supply sources and to determine how these techniques would affect the water quality, design criteria, and problems associated with the infiltration of high streamflows from the Little Arkansas River to the Equus Beds aquifer. Water intended for artificial recharge is captured either by a diversion well adjacent to the Little Arkansas River or direct diversion of surface water from the Little Arkansas River. Three recharge techniques are being evaluated: direct well recharge; surface-spreading basins; and a recharge trench. The demonstration project also will evaluate the potential added benefit of deterring the migration of saltwater from nearby areas into the existing Wichita well field.

The objective of the USGS part of the study is to determine existing water-quality conditions in the study area and to evaluate the effects of recharge on the quality of groundwater at two demonstration sites near the towns of Halstead and Sedgwick. USGS began data collection at surface and groundwater sites in February 1995 and is planning to continue collection through at least September 2005.

At the Halstead recharge site near Wichita Municipal Well No. 4, the aquifer is being artificially recharged by water pumped from a diversion well immediately adjacent to the Little Arkansas River. Pumping induces flow from the river into the adjoining Equus Beds alluvial aquifer; the flow is then captured by the diversion well. The diverted water (about 1,000 gallons per minute) is piped to the recharge site and artificially recharged by direct well injection, through surface-spreading basins, and through a recharge trench. Changes in water levels and water quality are monitored before and after recharge in shallow and deep monitoring wells at the recharge site.

Water intended for artificial recharge at the Sedgwick site comes from a surface-water intake in the Little Arkansas River. The surface water is treated with powdered activated carbon and polymers to remove organic contaminants and sediments. The treated water is then piped about 3 miles to the recharge site and recharged through surface-spreading basins near Wichita Municipal Well No. 36. The recharge water quality and quantity and changes in water levels are monitored before and after recharge in monitoring wells adjacent to the recharge site.

The Equus Beds Groundwater Recharge Demonstration Project is funded through a cooperative effort among the city of Wichita, Bureau of Reclamation, and U.S. Geological Survey (USGS). The last two agencies are part of the U.S. Department of the Interior. Equus Beds Groundwater Management District No. 2 (GMD2), Burns and McDonnell Engineering Company, Mid-Kansas Engineering Consultants, the U.S. Environmental Protection Agency (USEPA) and Kansas State Agencies also are contributing expertise and personnel to design and study the effectiveness of the recharge demonstration project. Burns and McDonnell Engineering Company manages the overall project for the city.