By Tom Fuszard
Communities and sewage districts looking to save on repairs to leaking laterals are finding chemical grouting a great option. For pipes that are structurally sound, it is often the best method to use. Sugarloaf Township, IL, used this process and discovered that the project paid for itself within approximately two months.
Located in St. Clair County in southwest Illinois, Sugarloaf Township is just outside the Village of Dupo and not far from the Mississippi River. The township contracts with Dupo for sewage treatment. According to Dennis Foutch, head of operations and maintenance, the township’s system was installed around 1980. It is comprised of 19 lift stations and about 15 miles of 8-inch pipe (mostly SDR-35) and serves 980 customers.
Foutch, who started in early 2015, likes to look for problems to solve. He found a big one in early 2016. The system was delivering about 8 to 10 million gallons a month of sewage. At $3.67 per thousand gallons, the bills were “getting out of hand,” Foutch said.
Each lift station has two pumps which should run about an hour a day each. He discovered that at one lift station (H, on State Street), each pump was running as much as 1.6 hours per day. Inspecting the pumps and impellers revealed nothing wrong.
Unable to televise and rehabilitate their pipes with internal resources, the township called in contractor Visu-Sewer Inc. which had assisted them in the past.
Televising discovered numerous issues, according Jon Kremer, senior design engineer at St. Louis-based Gonzalez Companies LLC, the township’s contract engineering firm. Many of the laterals connected to the mains by way of a tee. Some of the tee’s had rotated and broke; in other cases, the laterals had separated from the tees. It’s the proximity to the Mississippi River that puts the pipes at risk, Kremer said. The water table is only about two feet down. During certain times of the year the whole area becomes super-saturated. Traffic loads cause manholes to settle and pipes to crack.
The only corrective measure available to the township, Kremer said, would be to dig up and replace the laterals. That process could run as high as $5,000 per lateral, including excavation and repaving.
Visu-Sewer offers a host of services to solve problems in a sewer system, according to Barry Howell, business development specialist for Visu-Sewer Missouri LLC, in East St. Louis, IL For this project, the company quoted lateral sealing services.
Working manhole-to-manhole, Visu-Sewer first televised and cleaned the mains as needed. Next they sent in the lateral grout packer. This device can be maneuvered to fully envelope a portion of the lateral and the connection, even one at a 90-degree angle. The portion of the lateral to be grouted is isolated by inflating the packer on both sides of the lateral connection and extending a bladder up the lateral to isolate the first five feet (or more). The isolated area is first pressurized up to a maximum of five psi for 15 seconds.
“If the pressure in the void area drops more than two psi in 15 seconds, the lateral has failed the test,” Howell explained. “If a lateral fails a pressure test and it’s bleeding off air, we know it’s also got enough gap that water is perking.”
At that point, Visu-sewer pumped Avanti AV-100 acrylamide gel grout into the isolated area. With nowhere else to go, the grouting material is forced through the cracks, fills the voids and merges with the backfill material. The two-part liquid solution gels in under a minute, creating an impermeable barrier outside the cracked or separated joints. “I call it installing outside gaskets,” Howell said.
Then the sewer specialist re-applied the air pressure test. After confirming that the area is sealed, the team extracts the packer and moves on to the next lateral.
The entire project, which entailed inspecting about 30 laterals and rehabilitating seven, took two days. “It’s an excellent rehabilitation tool for structurally sound laterals that just leak,” Howell said.
One aftereffect of chemical grouting is extraneous gelled grout that peels away gradually over time from the interior of the pipe after a successful procedure. Randy Belanger, sales manager for Visu-Sewer in Pewaukee, WI, said this excess material is a natural consequence of the grouting process.
Some grout forms between the packer and inside wall of the pipe. “This residual grout breaks off over time and flows downstream,” Belanger explained. “The sealed connection is still fine. The sealing process takes place outside the pipe, and is not affected as this residual grout washes away.”
Chunks of the rubbery material vary in size, but usually are small. They are captured by the intake screens and don’t present a problem for the treatment plant or pumps.
Can a small leak make a difference? Howell offers this formula: A leak of 1 gallon/minute equates to 1,440 gallons a day. That’s 525,000 gallons a year. If your cost is $1.50 per thousand gallons – a conservative figure, he admits, when compared to Sugarloaf Township – that simple leak adds $787 a year in treatment costs alone.
“I describe it as a death by a thousand cuts,” Howell explained.
After rehabilitation, the flow rate at lift station H dropped 18,000 gallons a day, Foutch said. With the rate now at $4.17/thousand gallons, the repair means even more to the township’s taxpayers.
“We’re saving all kinds of money by fixing that problem,” he said, estimating the project paid for itself in two months. “As of right now, I’m 100 percent happy; so is the board.”
Those are the kinds of results that are typical with this process. “It has been our experience that we can take their money, their budget, and really stretch it if we just do grouting where grouting is indicated,” Visu-Sewer’s Howell said. “It is really a budget stretcher.”
Not only do communities save money with grouting, but these repairs help them meet EPA’s standards regarding clean water at treatment plants.
Kremer of Gonzalez Companies said communities need to be cognizant of their sewage flows, even with newer systems. Referring to Sugarloaf Township, he said they “went on a mission to locate: to find these things and repair them.”
Howell added that while grouting is typically a great option, it’s not the only one. Each situation is unique, he advises, so make sure you evaluate thoroughly. Then decide on the best solution.
In an era of tight budgets, it’s important for communities to be mindful of all their options. Chemical grouting can save a tremendous amount of time and money.
ABOUT THE AUTHOR: Tom Fuszard is a business writer from New Berlin, WI. He can be reached at firstname.lastname@example.org.
Proper Bidding Ensures A Successful Grouting Procedure
While it’s good to save money on pipe rehabilitation projects, going for the lowest bid without well-written specifications can actually hurt over time.
Visu-Sewer’s Randy Belanger said that bids typically don’t call for a set amount of grouting material per connection/joint or project, which leaves it up to the contractor to estimate the failure rate and the amount of grout needed. Each leak is unique, however, and requires a varied amount of grout to be sealed thoroughly. Under many project specifications, there is no allowance beyond the estimated industry average – and, therefore, no incentive – for pumping additional material when needed to complete the job properly.
A better method of bidding, Belanger said, involves specifying an assumed failure rate and an estimated per-gallon quantity of grout material per failure. In addition, adding a per-gallon line item to the bid form for additional grout needed beyond what is called out in the base bid will ensure each failure is thoroughly grouted. This would encourage contractors to pump the amount of material needed for each seal without additional unexpected cost. The final per-lateral cost would reflect any additional grout needed throughout the project.