Tennessee American Water Completes Underwater Pipe Repair

chattanooga

By Grady Stout & Kevin Kruchinski

The sudden surge of water flow to the northern part of the water system in the Chattanooga, Tenn., in the early morning hours of April 4, 2016 was unexpected. It was also indicative of a problem for Tennessee American Water, a subsidiary of American Water.

Tennessee American Water’s leak detection team identified a leak as coming from the 30-in. main under the Tennessee River that delivers water to north Chattanooga. There was a rippling at the surface of the river there, which indicated a fairly significant break and water was getting out of the main. The company wasn’t receiving any calls from the 20,000 customers in this area indicating a water main break on the street, so it was apparent that this was where that surge of water was going. A scuba team was sent in to investigate and captured video of the break, and a process of closing off the main began.

The Challenges

The break left the entire north part of Tennessee American Water’s system fed by a single 16-in. main that runs across a bridge, which limited the flow to North Chattanooga. This resulted in a partial lane closure to allow pedestrians to detour around the water pipe while remaining safely out of the way of traffic.

Customers noticed low water pressure during that time, so the company initiated two plans: one to fix the 30-in. main, and the other to provide some redundancy to the 16-in. main that was now serving all of North Chattanooga.
The company immediately mobilized resources to begin restoring the line. Within 24 hours, Keystone Pipeline, a contractor specializing in this kind of repair work, was brought in to address fixing the broken main.

Several sections of the nearly 1,600 ft of the new 24-in. pipe installed under the river.

Several sections of the nearly 1,600 ft of the new 24-in. pipe installed under the river.

The Solution

Keystone Pipeline’s solution involved sliding a new, plastic 24-in. main inside the broken concrete of the 30-in. main. Entrance pits were excavated on both the north and south side of the main near the river, and the new 24-in. main was slid inside and pulled through the broken main.

If there had been any significant bends in the broken concrete main, the 24-in. pipe the company was sliding wouldn’t have been able to make those bends and this solution wouldn’t have worked. Within three days of identifying the problem, the team installed a 2,000-ft temporary main across a heavily utilized pedestrian bridge to provide redundancy to customers. Access to the bridge required an emergency access agreement and extensive communication between the project team and local city officials and staff.

Within seven days, the Tennessee American Water project team had pulled 1,600 ft of HDPE pipe under the Tennessee River. Due to the buoyancy associated with HDPE pipe, the team worked through a solution to prevent the 113,000 pounds of pipe from floating to the top of the river.

The company also reached out to a neighboring utility to the north about the possibility of hooking up with it’s system to provide emergency access, though as it turned out, that was not necessary. But redundancy was covered if the 16-in. main was to fail.

Once the new 24-in. main was secured inside the broken 30-in. main, it was brought online and tested for bacteria that night, and after a few final issues were resolved, the pipeline was placed in service just two weeks after starting the project.

Tennessee American Water employees work on installing a valve in preparation for the new pipe.

Tennessee American Water employees work on installing a valve in preparation for the new pipe.

Looking Ahead

The new 24-in. line is a permanent solution, but plans were already in place to lay a new 30-in. line beneath the river in 2017, which will then provide three lines across the river – the new 30-in. line, the 24-in. line recently installed inside the broken 30-inch line, and the 16-in. line that served North Chattanooga by itself for a few days during this event.

The replacement pipe is made of a more dynamic type of material and pipe’s circumference is thicker and has the ability to bend.

Although the repair of the river pipe presented challenges, particularly the installation of the temporary pipe on the Northshore area, the company was appreciative of the cooperation and patience the community showed.

Kevin Kruchinski is the director of operations and Grady Stout is project engineer manager for Tennessee American Water, the largest investor-owned water utility in the state, providing high-quality and reliable water and wastewater services approximately 390,000 people.


About the Authors

grady-stoutGrady Stout | Project Engineer Manager, American Water
Grady Stout is project engineer manager of Tennessee American Water. In this role, his responsibilities include managing various projects, and helping deliver Tennessee American Water’s capital budget each year. Stout has been with company since 2013.

 

kevin-kruchinskiKevin Kruchinski | Director of Operations, American Water
Kevin Kruchinski is director of operations for Tennessee American Water. He is responsible for overseeing operation function areas such as water quality, field operations, production and maintenance within the state. He began his career at Kentucky American Water in 2006.

 

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