Sitting Ducks

Your streets are full of big and easy targets in the never-ending battle against inflow and infiltration and all its insidious costs

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In the campaign against I&I, there are lots of enemies you can’t readily see. Broken mains and laterals. Illegally connected sump pumps, downspouts and foundation drains. Pipe joints lying below seasonal high groundwater.

And then there are some you can see quite easily — manholes, which are part of the focus of this month’s issue of Municipal Sewer & Water. You drive over them every day on the way to work. Your people pop them open regularly when cleaning and inspecting lines.

They are right there — and they can add a lot of clear water to your sewers and ultimately the treatment plant if they are old and decaying or are not properly sealed. While estimates vary, studies have shown that 30 to 50 percent of infiltration to sewer systems comes from manholes and other underground structures.

Of course, you knew this — or if not the actual numbers, the basic fact of leaky manholes and their costs. In a perfect world, you would have enough budget to go in and fix them all on some reasonable timetable. But you also know the reality, all too well.

 

Finding fixes

This month’s issue looks at three communities that are going hard after manhole leaks — with different tools and technologies, but with similar dedication. What strikes me after reporting on public infrastructure since we launched this magazine in 2006 is the sheer variety of remedies for manhole leakage.

They range from incredibly simple and cheap to highly sophisticated and effective. It seems any community that’s at all serious about tightening manholes can find workable solutions that fit the budget. Here are some I’m aware of without resorting to much beyond a search of the memory banks:

• Inexpensive metal or plastic dish inserts that sit just under the manhole cover and keep water from entering there.

• Watertight manhole frames and covers that help seal water out.

• Internal chimney seals and external wraps that are cost-effective and easy to apply.

• Chimney and joint sealing compounds in a wide range of materials.

• Cured-in-place liners that essentially create a new leak-free interior.

• Poured-in-place concrete restoration that creates a new structure inside the old.

• All manner of cements, mortars and patching products that can be applied directly to the structure.

• Chemical grouts that flow into the surrounding soil and stop leakage from the outside.

• Trowel-on or brush-on epoxy sealers.

• Machines that cut old manhole frames to enable easy replacement.

• Spray-on coatings that save time.

• Rapid-set sealers.

 

Many choices

Keep in mind that those are only the categories. There may be two, three, four or a dozen or more specific solutions within each of them. And that’s not to mention all the tools for inspecting manholes and assessing their condition.

If you’re declaring war on I&I, you have a lot of weapons at your disposal. You don’t need to spend a fortune to get started, and you don’t need a ton of training before your people can go to work on the problem.

All this is a long way of saying: Where there’s a will, there’s a way to put a dent in leakage from manholes. Explore this issue and see what potential solutions you can find. Poke around online for a while. You just might discover something you didn’t know about that fits your manholes like a glove, and works within your budget, too.

The manholes are out there — like sitting ducks. Maybe now is the time to go on the attack. F

Comments on this column or about any article in this publication may be directed to editor Ted J. Rulseh, 877/953-3301; editor@mswmag.com.



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