Citizens Reservoir

Developed by Citizens Energy Group, the Citizens Reservoir project will ensure adequate water supply to accommodate population and regional economic growth over the next 20 years at a fraction of the cost of building a conventional reservoir. When construction is complete in 2021, the 90-acre, 230-foot-deep former limestone quarry will become the largest reservoir built in Central Indiana since 1968. It will store 3.5 billion gallons of water, or about 50 percent of the capacity of adjacent Geist Reservoir but with a much smaller footprint. Citizens Reservoir will be vital to helping the region surmount serious drought conditions that caused mandatory water restrictions in the past.

As the geotechnical engineer of record, Schnabel was instrumental in evaluating design alternatives to help the owner select a cost-effective approach. The selected alternative incorporated key design elements including a raw water intake, pump station, raw water transmission main, access road, rock and soil slope stabilization of the quarry high-walls and rim, and site perimeter fencing.

Our project scope comprised subsurface investigation; hydrogeologic model review of groundwater influence on neighboring properties during reservoir filling and operations; development of geotechnical data and engineering reports; and design of the facility’s tunnels, shafts, and tunnel protection canopies to prevent rockfall blockage. The raw water intake features a 220-foot-deep 9-foot diameter shaft and a 235-foot-long tunnel, and the pump station has three 220-foot-deep, 36-inch-diameter well shafts and a 340-foot-long tunnel. The tunnels were constructed using the drill and blast method, and the intake and the pump station shafts were constructed using a raise boring machine.

Second image in slideshow © Chris Whonsetler Photography.