There are more than 2,000 manholes in the city of Hays and each one requires some rehabilitation about every 50 to 60 years.
The time has come for the city to repair an estimated 20 of its manholes that are showing signs of wear, like crumbling soft concrete or failure of the iron ring encircling the opening, according to Jeff Crispin, director of the city’s Department of Water Resources.
“It’s kind of hard to predict. We know that we have a lot of manholes that we need to do every single year,” said Crispin, speaking Thursday evening to the Hays City Commission during its regular work session at City Hall, 1507 Main St.
Failure can block a sewer line and cause overflows, or worse, people and vehicles can be harmed in the event of a manhole collapse, Crispin told the commissioners.
He recommended the city hire Wichita-based Utility Maintenance Contractors L.L.C., which submitted the lowest bid of $60,000 in response to a request for proposals from the city. The commissioners will vote on whether to award the contract at their regular meeting next Thursday, Sept. 13.
“The sewer would remain in service,” Crispin said. “We don’t foresee any situation where we’d have to have the sewer out of service.”
The city identified the manholes, which allow access to the city’s sewer system, after video inspection of sewer lines in 2013 revealed structural problems.
The city doesn’t have the equipment to deal with very deep manholes and has historically hired a contractor to do the work on deeper ones. The last time manholes were repaired was 2015, he said.
Most of the ones needing repair now are on the Highway 40 bypass, along an area of Interstate 70 near Home Depot, and at 13th Street and Harvest Road.
“We went out and looked at the ones that basically need the most attention,” said Crispin, showing a picture of a manhole on the main sewer line that comes from north of Interstate 70 and that crosses by Home Depot.
“That’s basically our one connection. It takes everything from north of I-70 into our system,” he said. “Obviously that takes everything, so it’s going to have some issues.”
Not all the manholes are in the street, in fact some are out in the fields and ditches, which get less wear and tear.
Rehabilitation with fiber reinforced concrete and new rings extends the lifespan of a manhole. The cost runs about $2,500 to $3,000 for each one, compared to $15,000 or more for manhole replacement, Crispin told the commissioners.
The manholes, 48-inches in diameter, range in depth from about 8 feet to more than 20 feet. Typically they deteriorate from acidic environments, which causes the concrete structure to crumble away, but also from erosion, freeze-thaw cycles, the ground settling and shifting, age and storm water infiltration.
Along with manhole repair, Crispin recommended the city continue its annual program of cleaning out about 20 miles of the city’s sewer lines to maintain them and keep them operating properly. The problem is debris, he said, which is anything that can build up in the pipes.
“Anything that gets flushed down into the sewer lines that doesn’t make it’s way down to the sewer plant. You have things that get into the sewer lines, such as roots, soils, rags that get flushed and things that shouldn’t be flushed down the toilet that get down in the sewer lines that maybe get stuck,” Crispin said. “Grease shouldn’t get flushed. Grease gets stuck in a line.”
This will be the sixth year to clean the pipes, most of which are clay, ductile iron or PVC. Most of the pipe is 8-inch, 10-inch and 12-inch, he said, and requires only a light cleaning, but not always.
Crispin recommended Professional Pipe Services, Pro-Pipe, Denver, Colo.
“Overall the bid from Pro-Pipe totals just over $98,000 to perform light cleaning of the 105,000 of linear feet,” Crispin said. “Staff expects that there will be some medium and heavy cleaning that will be performed in certain areas of this project area, but that will not be known until we are inside those lines cleaning.”
Light cleaning with a nozzle into the pipe is one pass, while medium and heaving cleaning are repeated passes.
“The nozzle is pushed with a jet of water through the pipe from manhole to manhole and the debris is collected at one of the manholes and disposed of at the wastewater treatment plant,” he said. “So that debris is not pushed down the system to stop at another area.”
Cleaning prevents sewer backups, manhole overflows, public exposure to raw sewage and regulatory fines, he said.
The city has budgeted $150,000 and Crispin explained that depending on the level of work required when crews get to cleaning the lines, they’ll do the 20 miles as well as any additional repairs.
The total bid is for one pass, and that accounts for 93 percent of the project, he said, but cautioned that there will be some extra cost for medium and heavy cleaning.
“We do know we are going to tend to have some of those areas,” he said. “You may have some in restaurant areas, those you typically will have some, because you may have some grease that is put down the drain, but you can’t predict it very easily, but we do have a budget that we can work with.”
Commissioner Shaun Musil asked Crispin if he doesn’t already have some idea which areas are going to require more cleaning, and thus cost more.
“In certain areas you would,” Crispin said. “But when you’re dealing mostly with 8-inch lines, those aren’t typically your higher carrying lines. But if we were dealing with lines that were closer to most of the restaurants or downtown, that might require more medium and heavy cleaning.”
City Manager Toby Dougherty explained that baseline funding of the project is $98,000, with heavy and medium cleaning adding more.
“That could be $10,000, it could be $25,000. We don’t know what roots and tap intrusion add ons might be so we might end up with the program costing $125,000 or it may cost $135,000,” Dougherty said. “Just because the $150,000 is the do-not-exceed amount, doesn’t mean we’re going to spend all of that. We’re going to get the 20 miles done and we’re going to get the heavy cleaning done and everything we’re going to do, but only if the program allows it.”
Also, video inspection of the lines is part of the contract. It detects flaws and problems before catastrophic failure, like cracks, holes and tree root clogs. Using the video, city crews then remove the roots and chemically treat the lines.
Professional Pipe Services submitted the low bid for light cleaning, which ranges from .91 cents a linear foot for 8-inch pipe to $1.31 a linear foot for 30-inch pipe. The company won the 2016 contract and the city was happy with the job they did, Crispin said.
In other business:
• The commissioners heard a proposal about a new city pay plan for city employees, were briefed on the city’s information technology system and projects, and heard a recommendation for the purchase of three new trash trucks.