Utility crews use adjustable risers after repaving to keep potholes from forming when St. Louis’ 200,000 water and sewer manholes are below grade. As a result, snowplow operators don’t have to worry about catching the rims.
Scott Fier Utility crews use adjustable risers after repaving to keep potholes from forming when St. Louis’ 200,000 water and sewer manholes are below grade. As a result, snowplow operators don’t have to worry about catching the rims.
“It’s possible to stack the risers, but I prefer not to,” says Metropolitan St. Louis Sewer District Operations Director Jonathon Sprague, PE. The galvanized steel unit has a screwdriver-activated turnbuckle that makes tightening easy.
“It’s possible to stack the risers, but I prefer not to,” says Metropolitan St. Louis Sewer District Operations Director Jonathon Sprague, PE. The galvanized steel unit has a screwdriver-activated turnbuckle that makes tightening easy.

With a population of 320,000, St. Louis is the 60th largest U.S. city. But due to an unusual arrangement, the metropolitan area (population about 3 million) and surrounding county (1 million) are served by the nation’s fourth-largest sewer district, just behind New York, Los Angeles, and Chicago.

“We’re odd,” Metropolitan St. Louis Sewer District Operations Director Jonathon Sprague, PE, says cheerfully. “We cover the city and county and about 90 small municipalities. It’s an extremely large system, and we have to be efficient. We want to do a job once and not have to come back for a long time.”

His counterpart at the city’s water utility feels the same way. Together, the two manage close to 200,000 manholes. For at least 15 years, they’ve used the same solution to raise manholes to grade after paving, a tedious and potentially dangerous task their crews perform thousands of times annually.

One man inherited the product when he came to the job; the other introduced it to his utility after an extensive pilot test. Today, they use the product to keep potholes from forming when manholes are below grade as well as after repaving projects. With virtually all manholes at grade, city snowplows don’t catch the rims and do damage.

Second opinion confirms initial specification

The sewer utility was using the Pivoted Turnbuckle Manhole Riser when Sprague took over as director 11 years ago. Manufactured in the U.S. since 1978 by American Highway Products Ltd., of Bolivar, Ohio, it’s a flexible galvanized steel ring with a pivoted turnbuckle that gives the riser a plus or minus ½-inch adjustability range.

This means the riser can be slipped easily into the original manhole rim and expanded using a Phillips screwdriver, which acts as a lever. The turnbuckle enables one crew member to exert thousands of pounds of mechanical force with very little effort, securely seating the riser even in rims that are worn or out of round without straining.

“I knew they worked well when I started, but I evaluated them for myself and reviewed a couple of alternatives,” Sprague says. “Once I talked to the men using them and understood the difference the turnbuckle makes, I realized this was the correct solution for us.”

The turnbuckle also can be loosened, another benefit for crew members.

“We looked at risers that glue in and decided they were no good,” Sprague says. “They’re hard to remove when we come back in a few years. With the turnbuckle, we can loosen and replace the riser installed for the first paving lift with a taller one that will match the total height of new paving after the second lift. It’s very convenient.”

Riser heights start at ¾-inch and increase in ¼-inch increments. Likewise, risers can also be ordered in whatever diameters are needed and are shipped fully assembled. Small runs of custom-sized risers can be delivered within two weeks.

“There are a few cheaper risers, but the real cost is labor,” Sprague says. “We may have had a few fail in 15 years, but I can’t recall any examples. So for a few bucks more, we’re saving a lot of time and eliminating callbacks.”

Alternative to cast iron, concrete

Agreeing to test the turnbuckle riser in 1996 represented a major policy change for the St. Louis Water Department. The utility had given up on risers after nonadjustable cast-iron products proved ineffective and unsafe.

“We could never get them to seat well,” says Superintendent Vince Foggie. “They’d rattle and even pop out, leaving traffic and the public exposed to an open manhole. It was dangerous.”

For several years after the moratorium was imposed, crews raised manholes to grade by manually exposing and lifting concrete grade rings, a process that takes several hours and compromises new paving lifts. After jackhammering and raising, the newly raised rims were sealed in with concrete, creating seams in the pavement that wear faster than undamaged concrete.

It was a problem, so it made sense to do a pilot test with an adjustable riser.

“We put the riser in an intersection on one of our busiest downtown roads,” Foggie says. “It was easy to install, stayed put and didn’t cause any problems, and didn’t rattle. It was very encouraging, especially since we were getting behind on paving at the time.”

Because they’re relatively lightweight and stackable, the utility now keeps risers on hand in several thicknesses, and installs 200 to 300 annually.

“They save on labor,” Foggie says. “I don’t have to assign a crew to spend hours following a paving truck, which means they can be doing water department business.”

The city also specifies that the risers be used on state paving projects within city limits.

“They take 10 to 15 minutes to install, and we don’t have to remove any material or fill in with mix,” Foggie says. “Usually, we only have to close traffic down for a half hour or less. So they keep my crews and the public safer.”

It’s understandable that St. Louis temporarily gave up on manhole risers. But when exposed to a better solution, it’s commendable that managers subjected it to vigorous testing. By acting on the results, they’ve saved time and money and get more work done.

“In 15 years, we’ve had one fail, and that’s because we installed it in a worn frame that we should have replaced,” Foggie says. “When we did, we had no problems.”

Angus Stocking is a licensed land surveyor who has written about infrastructure since 2002. E-mail angusstocking@gmail.com.