A Model for Municipalities

Kansas utility’s in-house grouting program provides an efficient and cost-effective approach to reducing flow

A Model for Municipalities

The city of Olathe, Kansas, has an in-house grouting program for correcting inflow and infiltration issues. The utility’s I&I group has equipped a cargo trailer with all the tools, supplies and grout equipment they need to efficiently address problem manholes. 

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Inflow and infiltration is a budget killer for utilities of all sizes. In addition to the bottom-line issue of treating extra water, I&I can create problems with capacity, potentially limiting community growth or necessitating additional facilities.

Staying on top of I&I is critical whether the work is in-house or outsourced. In-house programs can be cost-effective options. Hiring freezes or other budget constraints might dictate outsourcing.

The city of Olathe, Kansas, has an in-house program that is a model for other municipalities. For several years, Olathe has used a system of attacking leaks with the use of chemical grouts. These products are a permanent solution to stop both seeping and gushing leaks, as well as to fill voids caused by water erosion or settlement.

Leaks are identified through several channels, including CCTV inspection and reporting from construction crews, manhole crews, and others involved in the sanitary sewer system.

“As we come across leaks, we rate them based on severity, create work orders, and prioritize them in our asset management system. A follow-up visit is made to determine the method we are going to use, whether it’s entering the manhole or probe grouting,” says Olathe Public Works’ I&I supervisor.

The I&I group equipped a cargo trailer with the tools, supplies and grout equipment they might need. This has also enhanced efficiency. The rig is ready to go whenever it is needed. The portability of the equipment means they have yet to find a manhole that they couldn’t access. Leaks are sealed in minutes rather than hours and usually do not require full street closures.

The City of Olathe believes that chemical grout is a good business decision. “Using grout isn’t a hard decision. It is very cost-effective. It is an easy tool to use and it works,” the Olathe supervisor notes. 

Another approach

Other municipalities prefer to outsource this work. In some cases, they do not have the luxury of hiring permanent staff. In other cases, outsourcing solves problems with employee turnover and training. Whatever the reason, there are qualified contractors around the country who can meet the I&I control needs of public works or utility clients.

Foundation Professionals of Florida serves several municipalities across the state. A high water table coupled with heavy rain events from tropical storms and hurricanes are a recipe for significant I&I and sanitary sewer overflows. Curtain grouting manholes with polyurethane foam is one of the main ways they tackle I&I for their clients.

The math makes a compelling business case for tackling leaking manholes.

If one manhole leak adds 5 gpm, 300 additional gallons of water an hour need treatment. If a system can handle 50,000 gallons per hour and average daily sewer flow takes — very conservatively — 75 percent of that capacity, it takes only 50 leaking manholes to overburden the system. From a cost perspective, that 5 gpm leak means 2.6 million gallons of additional volume to be treated. If treatment cost is roughly $3 per 1,000 gallons, that is $7,800 per manhole in a year. This does not take into account the cost to run the system longer to keep up with the additional volume nor does it include costly Environmental Protection Agency fines for SSOs or failure of the structures while in service.

Foundation Professionals of Florida uses a two-step method. After pumping out the manhole, they seal leaks with a hydrophilic polyurethane (Hydro Gel SX from Prime Resins) that forms a tenacious bond to the concrete or brick manhole and can accommodate the movement or vibration that many manholes experience. The crew then encapsulates the manhole with a watertight, structural polyurethane foam that meets NSF/ANSI Standard 61 for contact with potable water (Prime Flex 920). Sometimes a manhole is lined after that if it is degraded and needs structural support.

The trenchless approach keeps cost and traffic disruption down versus an excavation repair.

“We help a municipality better serve its customers and we do that in partnership with them. Their workers are right there with us,” says David Brown, Foundation Pros owner. “When we stop I&I, they can use taxpayer dollars for something other than treating extra wastewater.”



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