Minneapolis To Lay Historic Water Pipe Under The Mississippi

A massive infrastructure project planned in Minneapolis may solve decades-long water delivery problems posed by the Mississippi River once and for all.

Minneapolis has always relied on the Mississippi for its drinking water, though navigating the massive source body to deliver that water has never been easy. In the city’s early history, settlers pulled a riveted water pipe across the river. In the ’40s, a water pipe was hung from a local bridge. Now, with that pipe corroded and the bridge scheduled for rehabilitation work, the city will undergo the herculean task of installing a water main below the river.

“A high-tech machine will grind through rock deep below the Mississippi, carving a tunnel to keep one of the city’s most important drinking-water pipes safe from the elements,” according to the Star Tribune. “The $24 million microtunneling project is a first for the city, but the machines are increasingly being used across the country to help dig holes beneath tricky areas like rivers and freeways.”

The news outlet described the microtunnel boring machine as a “mechanical mole” that will dig a 5-foot hole several stories beneath the river. The city’s director of water treatment and distribution hopes the solution will last 200 years or more.

“Contractors will dig two wide shafts on each side of the river — one of them 130 feet below ground — to launch and retrieve the machine,” per the Tribune. “The toothed cutterhead will carve through about 900 feet of sandstone… A jacking system at the starting point will push sections of steel pipe behind the machine to advance the cutterhead and secure the tunnel.”

Ultimately, the pipe will deliver water to Minneapolis’ pressurized drinking water system, with flow based on level of demand. The pipe is expected to be one of the largest beneath the riverbed in the area, but by no means the first.

“There are about 1,400 pipes and lines crossing over or under water bodies in the metro area that carry wastewater, drinking water, natural gas, electric power, telecommunications and cable television, according to Minnesota Department of Natural Resources license data,” the Star Tribune reported. “The pipe north of Lake Street that still carries most of south Minneapolis’ wastewater was bolted together underwater in 1936 by divers navigating ‘pitch-dark mud’ at the bottom of the river.”

To read more about how water systems manage their pipes, visit Water Online’s Solutions And Insight For Water Loss Prevention.