Under city streets, several sewer pipes are seeing some sorely needed smoothing as work crews sheath their interior surfaces.
"We're doing a LCDBG (Louisiana Community Development Block Grant) sewer project, which is a grant project," Minden Director of Public Works George Rolfe, Jr. said. "We do one about every two years, and this one is about a $600,000 project.
"In some [sewer projects] we actually dig and do open trench," he continued "In this case we did in situ, which means in place."
Rolfe said the current project is approximately halfway complete and encompasses a number of areas south of Sheppard Street.
"This is to improve the sewer collection system," he said. "A lot of this was put in 50, 60, 70 years ago. It deteriorates over time and ground shifts."
Houston-based Insituform is doing the block grant sewer work through Farmerville contractor Don Barron.
According to Insituform representative Kevin Smith, the in situ process is a means of refitting sewer lines without having to tear up streets and replace pipe.
"We install a liner inside the old pipe," he said. "It keeps you from having to dig it up to replace it in any damaged or broken spots."
In the process, a long liner resembling a fabric tube is run through the old pipe.
"It's a felt composite with a resin – with a catalyst impregnated," Smith said.
The liner is stored in a refrigerated truck until it is used because, according to him, if it gets too warm the liner begins to cure.
Smith said it is run through the pipe by folding one end of the liner back over itself, securing it and essentially pushing the inside out with pressurized air.
"Like a sock, if you will, when you turn it right- or wrong-side-out," he said. "However long the 'sock' is, is how far you go. In this case it was approximately 600 feet."
Once the liner is in place and ready to be intentionally cured, 250-degree pressurized steam is forced down its length.
"That cures the catalyst within the resin so it forms and adheres to the old pipe, basically making a new pipe," Smith said. "It takes about 35 or 40 minutes to cool it down, and then we cut away the unnecessary liner."
The process adds approximately one-quarter inch to the interior of the pipe and can be done three or four times before the pipe needs replacing.
"The liner should last anywhere from 15 to 20 years," Smith said. "I've seen them go up to 30 before they call us in to run it again. It has a plastic layer on the inside, and it basically helps everything slide through."
The re-lined pipe as part of the sewer system is part of a closed system taking wastewater to treatment, according to Rolfe. The storm water system, however, primarily collects rain runoff through storm drains and channels it untreated through pipes, ditches and streams.
"When you flush your toilet you are getting what they officially call sanitary sewer," he said. "It goes into a contained system that ends up in the wastewater treatment plant. That's where we process it, clean it up and put it back in the streams.
"We have two primary basins that the storm water goes down," Rolfe continued. "The storm water goes down Cooley Creek or Mile Creek and eventually ends up in Dorcheat."