Blog: City Blog

Fixing Knoxville's 'Grand Canyon'

Fourth Creek, West Knoxville at Wellington Drive, 2019

In 1959, Fourth Creek in West Knoxville was simply that – a quiet tributary running parallel to Kingston Pike and somewhat insignificant.

That was before rapid urban growth began along Kingston Pike, which even by the early 1980s was not yet intruding into the health of the creek.

But in recent years, the creek banks located on Summit Medical Group’s Wellington Drive property have become highly eroded.

So eroded, Fourth Creek here is now 130 feet wide with 30-foot-tall banks.

“We call it 'Grand Canyon,'” said Jim Hagerman, Knoxville Director of Engineering.

While he smiles at the reference to the immense canyon in Grand Canyon National Park, the Director of Engineering calls this gulley the most serious erosion issue in the City.

“This situation is uncommon because the area the creek flows through has such deep soil and no bed rock to keep the creek from eroding downward.”

Sediment is a state-regulated pollutant, but the erosion at the Fourth Creek began before modern erosion controls were in place. Erosion requirements have evolved and today control both quality and quantity of water.

“Such federal requirements administered by the states were originally born out of The Clean Water Act of the 1970s and have improved greatly and strengthened over the years,” Jim Hagerman said.

Some of this crater-like tributary’s sediment goes all the way to Fort Loudon Reservoir, and some of it ends up in culverts downstream, says David Hagerman, City Stormwater Engineer Manager.

“Sediment doesn’t go away until we remove it,” Jim Hagerman said.

Even though this part of the tributary is not on City land, the eroding sediment flows downstream and can cause flooding, harming the communities and other City properties around it.

The tributary flows about three miles, crossing major thoroughfares Northshore Drive and Kingston Pike, which can become flooded as well as businesses.

“This work will take far more than any standard stream restoration,” said Jim Hagerman.

The goal? Creating a stable stream with water flowing and lots of rock to increase the elevation of the creek and protect it from future erosion.

Fourth Creek Project 1959

Fourth Creek Aerial Photo, West Knoxville, 1959

To meet the challenge, the City is partnering with property owners Summit Medical Group and contractor S&ME.

Called a hard-armor project, the Fourth Creek restoration is believed to be the single biggest erosion project that has involved the City.

The project includes taking nearly 7,000 cubic yards of existing soil on the site and placing it as a first layer of fill, followed by 2,300 tons of rock and then the addition of native plantings at the site.

The City’s investment as part of the partnering is $200,000. Approximate total cost of the engineering project is $820,000.

“This is absolutely the No. 1 pollutant source in Knoxville right now,” says Jim Hagerman.

“Fixing Grand Canyon will solve erosion and flooding and save money for the property owners downstream for many, many years to come,” said David Hagerman.

The restoration project begins this July and is expected to be completed in fall 2020.

Posted by On 12 July, 2019 at 1:23 PM