You have probably seen the contractor crews around Knoxville – clusters of men and women wearing reflective vests and hardhats, opening manholes, peering down into the depths of stormwater drains, then marking the water flow and depth measurements with chalk on the street or sidewalk.
The systematic effort, the first of its kind in Knoxville in decades, is mapping and evaluating the City's entire stormwater system – 25,000 separate parts and 400 miles of pipes.
The Stormwater Asset Management Survey – funded by $2.2 million through the federal American Rescue Plan Act, or ARPA – is about one-third finished and won't conclude until May 2024.
But when it's complete, it will be the City's most comprehensive tool ever in managing modern as well as some 100-year-old – and often unrecorded – pipes, catch basins, gutters, culverts and junction boxes.
And, as laborious and expensive as it is to collect, the data will ultimately save both money and hassle.
“This will allow us to better prioritize and proactively replace pipes and infrastructure that are in danger of failing," said Knoxville Mayor Indya Kincannon, who is proposing $800,000 in her 2023-24 budget for stormwater system upgrades, based in large part on the survey’s findings.
“Put simply: It’s dramatically less expensive and much less disruptive to property owners when we make smart, proactive stormwater infrastructure investments, rather than reacting to an emergency situation when something breaks.”
David McGinley, the City's Stormwater Engineering Chief, agreed that, by far, in the long run, “being proactive saves taxpayer dollars.”
“It’s not even close,” McGinley said. “The mindset is to identify the pipes that are nearing the end of their useful life, and cost-effectively address the situation.
“The alternative is to spend many times that amount of taxpayer dollars when there’s an infrastructure failure. No one wants that. A failed pipe can mean flooding, sinkholes, possibly damage to roads and extended closures while they’re being repaired.”
Let's say the survey discovers a buried pipe that has rusted out. Left alone, a hard rainstorm and a torrent of water could cause the corroded bottom of that pipe to finally give way, possibly causing public and private property damage, maybe even a road collapse. The repair might take weeks – or months.
But armed with precise data, City Engineering is able to fix corroded pipes before they fail. In fact, digging up a pipe often isn’t even necessary if the damage is spotted in time.
Using a rehabilitation process known as Cured-in-Place Pipe (or CIPP), a felt lining is inserted into a damaged pipe while it's still in the ground. Resin within the liner is then exposed to a curing element that makes it harden and adhere to the inner walls of the pipe. Once cured, the lining basically forms a strong new pipe within a pipe, extending its lifetime by roughly another 50 years.
No pipe failure. No sinkholes. No ecological damage. And no abrupt road closures.
Mayor Kincannon has proposed $800,000 for stormwater infrastructure remediation in her 2023-24 budget, presented to City Council last week at her State of the City Address.
The Mayor is proposing $300,000 in local funds for emergency drain repairs, and another $500,000 in City funding for proactive drainage improvements.
The ARPA funding and Mayor Kincannon’s proposed local funding are supplemented by a $20 million Tennessee Department of Environment and Conservation grant received last year.
The City is using the combined federal, state, and local money to catch up on a significant backlog of deferred stormwater maintenance.
"It’s a lot of money, but there are many needs," McGinley said. “We’re growing, with record amounts of new construction, and maintaining resiliency to weather requires modern infrastructure.
“We sometimes find clay pipes that were installed in the early 1900s. And on private property, you'll sometimes come across even worse cases where property owners years ago took illegal shortcuts. We'll find train box cars used as culverts, or old water heaters used as pipes.
“A healthy public and private stormwater system controls flooding and improves water quality. As the old adage says, we’re only as strong as our weakest links.”
McGinley thanked City Engineering Project Manager Randall Whitehead as well as the City’s contractor, CDM Smith, and subcontractor SAM Companies for partnering with the City, painstakingly collecting the data and then digitizing it, analyzing it and charting the path for priority repairs.
“CDM Smith is excited to partner with the City on this important project,” said CDM Smith Client Service Leader Daniel Unger. “Aging infrastructure is an issue facing all cities across the country, and it is great to see Knoxville take a proactive approach to stormwater asset management.”