Taking care of that underground utility

By Richard Shaw

It’s easy to know when some types of infrastructure in an area are either broken or nearing breakdown. Road coverings break up, utility poles are obviously weak and bridges obviously are falling apart from any inspection viewpoint.
But underground infrastructure is a different matter. Buried many feet beneath the surfaces of streets, yards and pathways, the deterioration of sewer and water lines only becomes apparent when something almost totally fails. With water lines, leaks occur and usually under pressure they cause sink holes or burst out onto a street, resulting in a mess and crews cleaning up and doing repairs.
But sewer lines are a different animal. Depending totally on gravity for operation, there is no pressure. The only time something appears wrong from the surface is when a line backs up and then the mess is more than just mud to clean up.
Sewer line deterioration can be costly, especially when it causes a disruption in service. As anyone who takes care of anything knows, preventative maintenance is a key to keeping failures at a minimum. In the sewer line business, and locally the system that the Price River Water Improvement District operates, a Sanitary Sewer Maintenance Program is a must; in fact it is set forth in state regulations.
“We have to clean and video inspect a certain percentage of our sewer lines each year,” said Jeff Richens, the District Manager for PRWID. “That percentage needs to equal to 100 percent of our lines every five years.”
That is some feat because PRWID has 87 miles of main sewer lines in the county.
“The fact is that by doing this, the life of the system is increased,” said Richens. “This helps us find problems while they are still small, before they turn into something bigger.”
Some of the most common problems workers who do this find in the lines are root balls from trees and grease buildup from businesses and industry. But cleaning in the past has also caused some problems that have been found as well.
Until only a few years ago there were no video systems used to look at the inside of the lines. Therefore when pressure jet systems were used to clean pipes, other than inspections that could be done from the manholes that were installed when the lines were put in, it was impossible to figure out if there was any ongoing problems, deterioration or possibly even damage done by the cleaning system itself.
The oldest and largest part of the PRWID system is made up of pipe composed of unreinforced concrete that was put in on 1971. That pipe runs along Highway 6 with some it in Martin, Carbonville and Spring Glen too. Deterioration over time and the make up of the pipe can be affected by the pressure jets from the system. Damage has been found since videoing began that was caused by many years of the unobserved cleaning. Newer lines that have been installed are made up of PVC thereby less susceptible to such damage.
The videos that are taken of the pipes must be kept through each cycle of five years so that, if needed, line deterioration and changes can be detected. Richens said that they intend on keeping the videos through two cycles.
The process is done by a large truck unit that cleans the lines. Then within two weeks after cleaning another unit with the video equipment and cameras comes back to view and record the lines to check for problems. If for some reason the video cannot be done within about two weeks, then the line must be cleaned again before the videoing is done.
“We pressure cleaned the systems for 30 years before we had video,” said Richens. “This has enhanced our ability to maintain the lines.”
In the past replacing deteriorated lines was a lot bigger project than it is now. The process called Cured In Place Pipe (CIPP) using a composite material slip liner is now put in when lines are too far gone. The material is heated up and pulled through a line from manhole to manhole and it takes the shape of the old line once it is inflated.
“It takes the shape of the old pipe and we only lose about 3/8 of an inch of flow space with the installation,” said Richens. “It saves a lot of time, problems and money too.”
This process was used on a line under Price City’s main street a short time ago, on a section that PRWID does control. The 270 foot section was done at a cost of about $31,000 for the slip method. The traditional method of digging up the street, replacing the line and then repairing the street afterwards would have cost about $100,000.
The crew that does the cleaning and video processes is specially trained to conduct the process. During the videoing they have real time viewing so they can see problems on the spot. The camera that rolls through the pipe has a head on it that can rotate so they can see in a similar way to that of a person using their peripheral vision. The camera also has different sets of wheels that can be put on based on the composition of the pipe. Plastic pipe requires wheels with more grip than a concrete pipe does.
The system is based in a control room in a trailer that serves as a studio for the returned video. The camera is operated much like a video game with a joy stick on a controller.
The entire inspection process also includes examining all manholes in the system as well as inspecting the three lift stations that are on the system in the county.
“Our main goal is to keep the system operating properly for our customers and to prevent any disruptions,” said Richens. “Doing that keeps costs down.”