Rehab project making progress
By Ethan Smith
Published in News on January 21, 2016 1:46 PM
The city's three-phase sewer rehabilitation project, which has seen numerous streets be torn up around the city, is roughly halfway complete.
City Engineer Marty Anderson said Phase II of the project is halfway done, and that the third and final phase is set to begin the bid process for work estimates in February.
"It can be very disruptive," Anderson said. "But it really benefits us overall, and benefits us in the sense of not having to treat rainwater in our sewer system, which is not very efficient."
The upcoming phase of the project will affect the east side of North William Street, with work being performed on sewer lines running perpendicular from U.S. Highway 70 that cross through several residential areas.
Phase II was supposed to be complete by Dec. 8, 2015, but heavy rains throughout the fall and winter delayed the project's completion.
A change order is in the works for the project, and Anderson said the city is hoping Phase II will be complete within a month.
Phase I cost the city $400,000, Phase II cost $1.3 million, and there is no estimate for what Phase III will cost yet. Anderson said he believes the combined price tag for all three phases will come out to $3.7 million.
There are several different forms of rehabilitation that have been going on throughout the project.
"Sewer rehab can be digging up lines and replacing them, it can also be lining the pipe with a PVC liner, which is actually called cured-in-place piping, and then you have manhole rehabs that are associated with that," Anderson said. "Manhole rehabs are putting a PVC liner in the manhole, or there is also a cement-like liner that goes in that resists the hydrogen sulfide gas that occurs in sewage areas."
Primarily, clay piping runs throughout the city and was installed decades ago. Over time, clay piping deteriorates and makes sewer rehabilitation projects such as the one currently going on necessary to prevent catastrophic line breaks or leaks.
"Over time the joints can get separated and let infiltration get in, and then the inflow is normally associated with other utilities getting put in and they may break through a pipe or something like that and mess the pipe up, and that allows infiltration," Anderson said.
Most commonly, storm water finds it way into the pipe and causes the city to have to filter and process water levels that are above a necessary capacity.
Another type of sewer rehabilitation work that has been going on during the three-phase rehab project is something called pipe bursting.
"What they do is they send a hydraulic unit into the pipe, and that hydraulically expands the pipe, and as they're pushing this unit through, they're pulling another pipe in," Anderson said. "That's when you're in cramped spaces. We're going to have one or two situations on the next phase that are going to require pipe bursting."
There were several factors that played into the city deciding to take on a sewer rehabilitation project that spans most of the city.
"We have so much water usage, and rule of thumb is that 80 percent of your water usage goes back into the sewer," Anderson said. "Our sewer flows are higher than our water usage."
This is an indication that there were problems within its sewer system that needed immediate repairs.
"That is normal, you have a certain amount of inflow and infiltration and inflow that you can allow, but ours is more than that threshold, so we're trying to bring that down," Anderson said.
And while citizens might be experiencing headaches having their streets torn up, there is a long-term benefit to the project, including improved sewage systems throughout the city and freeing up the city's reservoirs.
"To the average citizen, they may not notice a difference," Anderson said. "I mean, it could be that if the main line is deteriorated badly enough where we have a collapse in the pipe or something like that, it'll minimize them having backups and having sewer problems."
Anderson said the city is looking to pave the streets that have been damaged by the sewer work during the spring of this year.
"If it's an area that we're just doing pipe-lining, and we don't have to work on any lateral pipes, you know, you've got your main line and then sewer laterals running over to the right of way so you can pick up the house plumbing, and when you have situations like that, if you have to replace those laterals, then those are dig and replace," Anderson said. "So you'll be tearing the streets up. Walnut Street is an example, Mulberry Street is an example, and we've made provisions to pave those roads to fix them after they're done."