ENR May Issue 2023

Replacing Chimney Rings With HDPE Alternative to
Address Ongoing I&I Issues

Inflow and infiltration (I&I) is responsible for up to 20% of the flow being directed to wastewater treatment plants. This is according to a study done by Metropolitan Council Environmental Services, a regional planning organization serving seven counties in the Minneapolis-St. Paul region. That figure can rise up to 60% during major storm events. Reducing I&I by
replacing deteriorated manhole chimneys will not only result in an instant savings in a municipality’s treatment costs, in some instances, it may even lessen treatment demand to the point that planned facility expansions are no
longer necessary. While those figures make a strong case for a community to investigate and identify deteriorating chimneys, the
next step is determining the best course of action for replacing the concrete chimney rings, where a good deal of the I&I is occurring. “If you’re replacing deteriorated concrete with new concrete, you’re really just kicking the can down the road in terms of addressing the problem,” says Lana Wiedrich, CEO for LADTECH, Inc. “The sulfuric acid in raw sewage
has a destructive reaction to the properties of concrete, which compromises the concrete’s integrity over time.”
That chemical reaction is called microbial induced corrosion (MIC). For many utility operators and engineers, it is considered an inevitable condition that limits the useful life of a manhole chimney and necessitates that its eventual replacement be factored into
long-term maintenance costs. Despite the prevalence of the “that’s the way we’ve always done things” approach to
manhole chimney replacement, many communities around the country are beginning to see that there is a better
alternative. The LADTECH System is fast becoming the go-to solution to address the many downsides to concrete chimney rings. Manufactured from 100% Recycled Plastic Polyethylene, the Ladtech HDPE manhole adjustment ring is the most advanced option on the market today.” We can start with sustainability. Not only are our rings made from recycled materials, they’re also built to last up to 100 years, if not longer. They’re a much more cost-efficient option, both in terms of longevity and installation costs. And they can be put in in a
fraction of the time it takes to install a concrete ring, so there is less burden on public works crews and
less disruption to motorists,” explains Lana Wiedrich. Best estimates put the number of manholes in the United States at more than 20 million, with more than half of them over 70 years old and likely in critical need of repair or replacement. This is an ongoing maintenance
issue for public works departments throughout the country that are in need of a solution that addresses the shortcomings of concrete rings.
“From talking with public works crews, one of the biggest headaches with installing concrete replacement rings is matching the existing street grade. That’s not a problem with our HDPE system. We provide quarterinch spacers that provide the perfect height without shims or any guesswork,” says Dwight Wiedrich, owner and consultant for LADTECH. Although the LADTECH rings are far more durable than concrete, they are also lighter weight and easier for maintenance crews to transport and install. This ease-of-use factor is not only an important safety consideration, it also requires less manpower, allowing public works departments to spread out their resources to address other areas of need. Oftentimes, public works leaders are under pressure to direct funds towards infrastructure improvements that are highly visible so the public can see their tax dollars at work. Since manhole chimneys are beneath the surface and out of view, they do not provide the aesthetic appeal of a newly repaved road or reconstructed sidewalk.  But what will catch the attention of those overseeing municipal budgets is the investment-to-benefit ratio that can be realized by drastically reducing wastewater treatment costs through a relatively simple repair that will last up to 100 years. “The bottom line is that concrete manhole rings are out-dated technology and the faster they are phased out, the better it will be across the board,” comments Dwight Wiedrich. “The LADTECH HDPE rings are a cost effective alternative that will stand the test of time while helping communities address their CSO issues and reduce treatment costs by reducing I&I. And if you’re looking for one more reason— they’re made right here in America.”