City’s water, sewer department rehabilitating sewer lines

Gary B. Gray • Jan 18, 2012 at 11:17 PM

A relatively new technique is reducing the amount of earth displacement normally required during water and sewer line replacement.

Johnson City’s Water and Sewer Services Department has contracted with Mountain City’s Iron Mountain Construction to replace and rehabilitate about 3,330 linear feet of sanitary sewer lines in seven locations throughout the city.

The roughly $522,000 contract includes the rehabilitation and replacement of the 8- and 10-inch sewer lines as well as the replacement of 20 manholes. These improvements are under way in the areas of: Towne Acres, Knob Creek Road near North Hills Drive, Browns Mill Road, Sevier Street, East Springbrook Drive, Cedar Grove Road and Miami Drive.

“If you look at most of our replacements in the past, it was because of capacity issues,” said Tom Witherspoon, Water and Sewer Services director. “All of this is the result of a need to act on defective lines before they fail. On most replacements, you have to do a lot of digging. This job allows for less excavation by using recently developed methods that allow new pipe to be pulled in through manholes. We still have to have access points that may require excavation, but this method lets us use less.”

While some lines will be replaced, others will be rehabilitated by the removal of roots, cracks and open holes. Removing these defects will help reduce blockages that may cause sewer to back up into homes or onto the ground, causing a potential health hazard. Where possible, construction will be performed using a no-dig technology, which can be less disruptive to the surrounding area.

“They actually use a winch (to get) the new pipe in,” said Neal Whitten, Water and Sewer Services assistant director. “The interesting part of this is when they get to the point of working on a line, it takes very little time to complete the job.”

Whitten said the city’s goal is to replace 1 percent of the system annually, and this project is part of a systematic replacement of the sewer system before unexpected failures occur.

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