When a manhole lid isn’t flush with the road surface, you know it. Everyone who drives that road knows it.

Setting lids flush with the road surface and maintaining them at grade through years of traffic and road maintenance is a challenge every wastewater utility faces. Flat or crowned surfaces, upgrading existing infrastructure, old roads, new pavement — it’s hard to find a solution that fits all circumstances.

Cory Rackley, lead equipment operator, is responsible for keeping about 10,000 manholes in St. Charles, Missouri, precisely at grade. If they’re too low, citizens and council members complain, and if they’re too high, even by as little as a quarter inch, snowplows will catch and tear them out.

“We have old and new areas, which means we have a lot of odd-sized sewer structures,” Rackley says. “Adjustable risers make it much easier to raise all these differently sized manholes to grade.”

For years, his crews raised manholes to grade after new paving with traditional methods that required excavation and the use of concrete rings or bricks. But since 2008, he’s been using Pivoted Turnbuckle Adjustable Manhole Risers, made by American Highway Products, to raise manholes precisely to grade without excavation, significant traffic closures, or the need for equipment to lift and set heavy concrete rings.

“When we have a manhole to raise now, we can do it in half an hour or less, depending on traffic, without stopping traffic or digging up pavement,” he says. “Compared to that, the concrete rings were a nightmare — they’d take one to two days and usually required detours.”

The American Highway Products adjustable riser is a sturdy, flexible, galvanized ring made with American steel that uses a turnbuckle to adjust riser diameter. Installation is simple and fast; one person sets the riser in the original utility rims and uses a screwdriver as a lever to expand it to fit. Since the turnbuckle leverage applies thousands of pounds of force, the riser seats in the rim tightly, providing a new rim for the manhole with no rattling or play.

A new angle

While the company’s turnbuckle risers have been around for a while now, the new Inclined Manhole Adjusting Riser Rings are using the same technology to accommodate pitched surfaces. They feature a turnbuckle linkage pivoted at each end to expand the riser. A 60-pound force applied 7 inches from the center of the pivoted turnbuckle exerts a 5,600-pound tangential force in the rings that will be bent to fit the out-of-round, worn manhole opening.

Wisconsin-based Stark Pavement Corp. sets up to 100 Pivoted Turnbuckle risers annually in and around Milwaukee and has set as many as 35 on a single project. The firm has also used the inclined risers, which incorporate the same pivoted turnbuckle for easy adjustability, along with the capacity to tilt the riser as needed to match sloped road surfaces.

“We purchased the inclined risers for a project in Kenosha with a very high crown,” says Todd Beaber, paving supervisor. “It was nice to have the ability to exactly match the sloped surface, and it made for a higher-quality roadway.”

Stark crews install the adjustable risers just before paving. “We usually have a couple of guys working just ahead of paving machines,” Beaber explains. “It’s nice that these risers are so much lighter than cast iron risers — our crew can carry all they need in a small truck. Really, all they have to do is clean the old rim with a scraper, set in the new riser and tighten it. They’re done in five to 10 minutes.”

One key to the riser’s efficiency is precise sizing. They can be ordered at any diameter, as thin as 3/4 of an inch and up from there in 1/4-inch increments. “They can be ordered on short notice, but we try to keep an assortment in stock at all times,” Beaber says. “Sometimes we’re moving fast, and it’s nice to have exactly what we need on hand.”

“We’ve had no failures that I know of,” Beaber says. “I think they’re the best riser available and a good value too. Money is so tight on municipal projects, and these risers make it easy to get manholes to the right elevation without excavation and without any rattling.”

Good match

In St. Charles, city crews set 40 or more of the American Highway Products risers annually, and contractors set about the same amount. The city also keeps risers on hands, in multiple sizes, for their own use and occasionally for contractors. In the last year, Rackley has also started using inclined risers, a newer product from American Highway Products.

“Streets aren’t usually flat, so these have been great for us,” he says. “They let us make an even closer match to the final road surface. They’re a wonderful product, and there doesn’t seem to be anything else out there quite like them — we’ll certainly continue to use them.”