Thornton Quarry Reservoir

Sorensen Provides Electro-Hydraulic Solutions for Floodgate Operating Systems

Electro-hydraulic Gate Controls for Thornton Quarry Reservoir

Sorensen Systems Sorensen Systems developed the electro-hydraulic systems that operate a massive flood control gate system for the 300-foot deep Thornton Quarry Reservoir  near Chicago, Illinois. This enormous project, which is also known as the Deep Tunnel Project and the Chicago Deep Tunnel, is a large civil engineering project meant to reduce flooding in the metropolitan Chicago area. It also reduces the harmful effects of flushing raw sewage into Lake Michigan by diverting storm water and sewage into a series of deep, large diameter tunnels and vast holding reservoirs.

According to published reports, flood damage in Chicago’s metropolitan area has occurred over the past century with an alarming regularity. Major flooding took place in 1938, 1952, 1954, 1957, 1961, and 1973. Officials proposed the concept of a Deep Tunnel, which took years to be put into motion. The project, when completed, would help the community manage its water resources and prevent flooding.

The Thornton Reservoir project came to life beginning on Thanksgiving 2015, when it began to fill for the first time. The Metropolitan Water Reclamation District (MWRD) of Greater Chicago reported that the Thornton Reservoir filled to a depth of 17 feet, which was about 400 million gallons. For reference, the reservoir’s capacity is eight billion gallons. The rainwater and sewage drained slowly towards the reclamation plant. The Deep Tunnel needed to divert raw sewage and rainwater that resulted from a steady rain event. The reservoir’s capacity is eight billion gallons.

Gates Regulate Water Flow

The gates for this project regulate the flow of water through large underground tunnels constructed to slowly feed the stored water. The water makes it way to the Calumet treatment facility before being released into the Cal Sag Channel. Sorensen Systems designed and fabricated the hydraulic power units for four stainless steel roller gates, which Steel-Fab, Inc., of Fitchburg, Mass. manufactured. Each of the four gates weighs measure 18 feet wide and 28 feet high and weight approximately 100 tons. The gates, which can withstand 300 feet of water pressure, isolate the tunnels from the reservoir when necessary. The Programmable Logic Controller (PLC) ladder logic that monitors the gates, controls motion and performs coordinated multi-gate control. Casco Systems of Cumberland, Maine, developed the sequencing.

Engineer Programming Gate and Valve Operating System for Thornton Quarry Reservoir
Project Engineer Chuck Keyes programming the gate & valve operating system’s controls.

Thornton Quarry Reservoir Serves 500,000

According to information released by the Metropolitan Water Reclamation District (MWRD), over 500,000 people benefit directly from the protection to over 180,000 homes in the 14 communities to the south of Chicago. A spokesperson for the MWRD said, “We are happy to put our latest engineering marvel to work. The Thornton Composite Reservoir is the world’s largest reservoir and has drawn intrigue from across the world.”

The project ultimately consisted of 109 miles of tunnels, which ranged from nine to 33 feet in diameter. The roller gates along with the electro-hydraulic system that Sorensen Systems developed are an active part of that management system. Also, the quarry itself has been dug out to one half-mile in length from east to west and one quarter-mile wide from north to south. It will be one of the largest reservoirs of its kind in the world, according to the MWRD. See photos of the dam and quarry online at