MWU builds new water mains -- inside the old ones
Photo: Worker guides pipe relining material into water main
Embracing new technology
Imagine Badger Rd. completely gutted – nothing but dirt and gravel, impassable for months. Same story for West Mifflin St., and Droster Road. It's what would have happened had Madison Water Utility chosen to dig up and replace the aging water mains that run beneath those streets.
"We'd be actually digging a trench the length of the project. So you'd have an open ditch," describes Don Russell, a lead-worker with the utility.
Utility equipment operator Bob Kempfer estimates the work would have taken about three months on Badger Rd. alone. "They would have to tear it out curb-to-curb and reroute traffic."
But it didn't happen that way. Instead, MWU was the first water utility in Wisconsin to embrace a new technology called cured-in-place pipe (CIPP) rehabilitation, or simply pipe relining. In 2013, the utility essentialy rebuilt the water mains beneath a large section of Badger Rd. without ever tearing out the street above, something unheard of just a decade ago.
"You can essentially construct a new pipe inside of an existing deteriorated pipe," explains design engineer Adam Wiederhoeft. "We can rehabilitate a main that maybe has characteristics like adequate size, but it maybe has a lot of breaks ... We can reinvest in the deteriorated infrastructure and bring it new life at a lower cost."
(Scroll to the end of the story to see video of the project.)
Faster, cheaper, easier
In September, the utility launched its fourth major main relining project, the renewal of water mains in the Bunker Hill neighborhood on Madison's east side. The area was chosen because its 50 year-old water mains have a history of breaks.
"It's bad," says Al Larson, principal engineer with Madison Water Utility. He points to a detailed computer image of the neighborhood that maps out main breaks over the last several decades. On some streets, virtually every block is marked with a green "X" indicating a break. Add to that what Larson calls "chronic low pressure" in the neighborhood, and it became a prime candidate for water main renewal.
Photo: Madison Water Utility targets mains with a history of breaks for relining.
Relining mains for most of Bunker Hill should take four to six weeks, easily half the time of traditional replacement and about two-thirds the cost. Once the relining is finished, the utility will be able to boost the water pressure for the neighborhood with confidence that its mains can withstand the change.
"People will be able to water the lawn, flush the toilet, and take a shower all at the same time," Larson laughs, adding that more pressure also means better fire protection for Bunker Hill.
Planning for the future
Cities across the country are grappling with drinking water infrastructure that has reached the end of its useful life – much of it installed in the post-World War II boom more than 60 years ago. The American Society of Civil Engineers (ASCE) reports that there are about 240,000 main breaks nationwide every year, and the number is growing.
According to the 2013 American Water Works Association (AWWA) State of the Water Industry Report, deteriorating water and wastewater infrastructure is the biggest issue facing the industry today. The AWWA estimates replacing and expanding water infrastructure to meet customer needs in the U.S. will take a $1 trillion investment over the next 25 years.
Madison Water Utility is working to stay ahead of the curve with its long-range infrastructure plan, which calls for replacing or relining more than 400 miles of deteriorating pipeline over the next 40 years. Larson admits it won't be easy or cheap. At a cost of $950,000 per mile, replacing water mains is a significant and growing expense for the utility, adding up to millions of dollars a year. But he insists the time to act is now.
"People are not going to want to see their street dug up every year, disrupted service. People just get to that tipping point and they say 'No more. We've got to do something.'"
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