How traffic impacts today reduce headaches down the road

Two disruptive pipeline projects underscore the challenges of updating critical water infrastructure.

May 14, 2018 | By: Jay Adams

Construction work ahead. Road closed. Detour.

When you see these words prominently displayed across orange signs on your drive through the city, you know you have a long, and sometimes frustrating, journey in front of you.

But, in a lot of cases they also signal a valuable investment into the future of your community.

Construction crews lower a new water main into a trench along Colorado Boulevard in March 2018.
Construction crews lower a new water main into a trench along Colorado Boulevard in March 2018.

That’s exactly what the signs along a stretch of Colorado Boulevard near City Park and in Denver’s Highland neighborhood signified over the past seven months, where Denver Water completed replacement projects on water pipelines that were installed more than 100 years ago.

“These big projects take months of planning and have plenty of challenges along the way,” said Devin Shable, Denver Water project engineer.

Starting in October 2017, Denver Water replaced 6,800 feet of water mains along Colorado Boulevard, Montview Boulevard and East 17th Avenue. The $3.5-million project replaced the cast-iron pipes that dated back to the early 1900s with a new 12-inch-diameter PVC pipe.

“Colorado Boulevard is the busiest street in Denver, so we had to do all of our work at night to minimize the impact on traffic,” said Lance Paplow, Denver Water construction project inspector.

Crews had to wait until 7 p.m., when the afternoon rush was over, to start their work. Then, they had to be off the street the street by 5 a.m., before traffic picked back up the next morning.

Locating and working around existing utilities is one of the most difficult aspects of installing new pipelines.
Locating and working around existing utilities is one of the most difficult aspects of installing new pipelines.

“It’s hard work to dig up the street, remove the old main, install new sections of pipe and have the road open in time for rush-hour traffic,” Paplow said. “The construction crews have to work fast, smart and safe.”

On the $6 million Highland project, crews from Concrete Works of Colorado, replaced 4,500 feet of a 24-inch water pipe and added a new 30-inch-diameter pipe down the same corridor to improve water service in the area.

“The biggest challenge was locating and working around numerous utilities underground,” said Shable. “There were many layers of utilities under the street that we had to navigate to get the new pipe in place.”

Intersections near downtown were some of the most complicated parts of the project because there were multiple utility lines crisscrossing each other.

“We have to locate electrical, natural gas, fiber-optic, telephone, sewer and even our own water lines before we dig,” Shable said. “Once we find them, construction crews have to be extremely careful excavating the dirt around them to make way for the new pipes.”

Crews from Concrete Works of Colorado prepare a pipe for installation in Denver's Highland neighborhood in April 2018.
Crews from Concrete Works of Colorado prepare a pipe for installation in Denver’s Highland neighborhood in April 2018.

Another complexity engrained in these type of projects is working with various community agencies to address the impacts on traffic, bus and pedestrian routes, and coordinating water outages with schools, businesses and homes in the area.

“We know these big projects were an inconvenience for people in the area,” Shable said. “The good news is that these pipes will improve water service, and they’re expected to last for 75 to 100 years.”

2 thoughts on “How traffic impacts today reduce headaches down the road”

  1. From the Denver Water website: https://www.denverwater.org/project-updates/pipe-replacement
    “The water distribution system contains more than 3,000 miles of water mains, and [we] install or replace an average of 60,000 feet of pipe a year.”

    This equates to a 263-year replacement cycle. Why would that not match “expected to last for 75 to 100 years” stated above? How many miles of pipe are beyond their service life, and is that a problem?

    Thanks!

    1. At first glance it would appear that we would need to replace much more pipe annually than we are currently doing. But that costs money. Lots of money. If we were to replace just 1 percent of our pipe annually we might need to spend $30 million per year. Every year.

      But, that is not necessary. Pipe does not all fail uniformly over its lifespan. We look at the breakage rate in aggregate and from a probability perspective. How many years of life will we get until 10 percent of the pipe has broken. How many years until 50 percent of the pipe has broken? 90 percent?

      We look at current break rates and five-year rolling averages. One of the industry benchmarks is 15 breaks per 100 miles of pipe per year. Denver Water is currently around 11 and the five year rolling average is flat or even declining a little. That key measurement sort of suggests that, in the near term at least, we’re not overspending on pipe replacement and removing pipe from service that still has useful life.

      In an ideal world, we would replace pipe the day before it failed. For obvious reasons, that’s totally impractical. What we’re trying to do when we select mains for replacement is to find the worst pipe (from the perspective of performance, not age), find areas of bad pipe (the bigger the project, the greater the efficiency, the lower the unit replacement cost), be opportunistic (coordinate with other infrastructure projects), consider probability of failure and consequence of failure, etc.

      Developers also have a role in the main replacement story because redevelopment in areas with old water mains often results in replacement as part of the development project.

      In short, it’s a strategic balance to ensure we’re being responsible with ratepayers investment into the system while providing the highest level of service possible for our customers now and also in the future.

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