Lake Huron Water Supply Project / Tunnel Explosion
Lake Huron Water Supply Project
In 1968, to serve the water needs of a growing population, the Detroit Metro Water Department began work on the Lake Huron Water Supply Project. This massive feat involved erecting a submerged intake crib connected to a six-mile intake tunnel beneath Lake Huron. The mechanical mole that dug the 16-foot wide tunnel bored through the bedrock beneath the lake at a rate of 150 feet a day. The project excavated more than one billion pounds of rock. The water treatment plant pumped clean water into an 82-mile system of water mains supplying Detroit and Flint. When finished in 1973, the $123 million system boasted a capacity of 400 million gallons a day.
On Dec. 11, 1971, a shotgun-like blast claimed the lives of 22 men working on a water intake tunnel beneath the bed of Lake Huron. A pocket of methane trapped within a layer of Antrim shale fueled the explosion. An exhaustive inquiry determined that drilling for a vertical ventilation shaft from the lake's surface had released the trapped gas. A drill bit that fell ignited the gas. The blast created a shock wave with a speed of 4,000 miles an hour and a force of 15,000 pounds per square inch. Witnesses reported seeing debris fly 200 feet in the air from the tunnel's entrance. This tragedy resulted in stronger mine safety regulations and enforcement. It was one of the deadliest industrial accidents in Michigan history.