When it rains in Milwaukee, dangerous wastewater no longer pours into Lake Michigan, thanks to 9 newly added miles of concrete tunnel built by Shea-Kenny J.V. in partnership with Central Ready Mixed Concrete, a Prairie company.

The last 2.5 miles of the expanded system, planned more than a decade ago by the Milwaukee Metropolitan Sewerage District, will open this March, says Shea Vice President Martin “Dutch” Vliegenthart. 

The deep tunnels store excess storm water, preventing it from mixing with raw sewage and backing up into the lake – or into the basements of area homes and businesses, Dutch explains.

From the start, Shea-Kenny crews have relied on Central Ready Mixed to help them meet the demands of this multi-year project.

‘No room for delays’

“During this last phase, we’ve completed 175 feet of tunnel lining per day,” says Dutch. Each section of the 23-foot-diameter tunnel requires 110 cubic yards of fast-setting, high-strength mix, pumped below ground for distances up to a mile.

“When you’re placing 550 cubic yards per day at nearly 320 feet below grade, there is no room for delays,” says Dutch. “Fortunately, with Central we’ve never had to wait for concrete.”

It’s all in the mix

Having a quality control manager on every pour assures the consistency, flowability and fast strength Shea-Kenny needs, says Central General Manager Todd Schaller.

“We’ve monitored consistency, slump, temperature and air content on all concrete for this project,” he says. “Our experts are on-site daily to make sure every load we deliver meets all specifications.”

The mix, specially designed for Shea-Kenny’s tunnel work, is formulated to reach strengths of 1,200 psi within 8 hours. “This project calls for 4,000 psi, but we are getting 20% to 50% above that,” Dutch reports.

Shea-Kenny has earned awards from the American Public Works Association and the Wisconsin Ready Mixed Concrete Association for the deep tunnel project. But Dutch and his team take even greater pride in knowing the expanded system helps keep Lake Michigan clean.

“I am a long-time boater and I can see the difference in the water quality,” Dutch says. “We are pleased to be part of Milwaukee’s commitment to pure water and a healthy environment.” 

Looking inside Milwaukee’s deep tunnel project

27 million gallons
Stormwater storage capacity of the new 2.5-mile tunnel

$1 billion
Total cost of the overflow reduction system, built in 2 phases

455 feet
Length of the specialized drill that bored through bedrock to form tunnels

50+
Truckloads delivered daily from Central’s Hampton Avenue plant during the 2nd phase of construction

5,600 psi
Average 28-day strength of tunnel mix custom formulated for Shea-Kenny

70 billion gallons
Estimated volume of wastewater kept out of Lake Michigan to date by the new system