Irwin Drain

Spalding DeDecker is performing a study for a segment of the Irwin Drain. Due to the record high Lake St. Clair water levels, the Irwin Drain is consistently backwatered, which causes bank erosion and attracts waterfowl.

The birds are an issue because the drain is located at the north end of Selfridge Air National Guard Base. Flocks of waterfowl flying in the airspace increases the risk of a plane/bird collision. Our study investigated the possibility of using a combination of dams/gates to block lake water, while also draining the Irwin Drain during normal flow. Our hydraulic modeling provides two temporary solutions and two long-term permanent solutions for the drain.

The Challenge
The project essentially has two major conflicting goals. One option is to block incoming Lake St. Clair water levels with a dam-like structure and dry the drain. The second option allows flow conveyance through the Irwin to prevent flooding of adjacent businesses. These two goals conflict in that any traditional dam structure used to block the lake water from entering the Irwin will also block Irwin Drain flows from exiting the drain.

The Solution
The preliminary solution will likely include an adjustable, inflatable dam set to automatically inflate and deflate based on a water level sensor within the drain. This would allow Irwin Drain flows to exit through the deflated dam during high flow events while also block lake water with an inflated dam during dry weather. Low flow or base flows through the Irwin drain will be conveyed around the inflated dam via a small pumpstation.

The Impact
The intended impact of the project will be to keep the Irwin Drain dry which will in turn discourage possible waterfowl/aircraft strikes. At the same time, incorporation of a dam reduces shear forces within the drain which addresses the bank erosion.