Metropolitan St. Louis Sewer District relies on innovative manhole risers
By Angus W. Stocking
With a population of about 320,000, St. Louis, Mo., is the 60th largest city in the United States. But due to an unusual arrangement, St. Louis’ metro area (population about three million), and surrounding St. Louis County (about one million), happens to be served by the fourth largest sewer district in the United States, just behind New York, Los Angeles, and Chicago.
“We’re odd,” Metropolitan St. Louis Sewer District (MSLSD) Director of Operations Jonathon Sprague, P.E. says cheerfully. “We cover the city and county of St. Louis, and about 90 small municipalities. So it’s an extremely large system, and we have to be efficient—ideally, we only want to do a job once, and not have to come back for a long time.”
Just how large is the MSLSD? Sprague cites one important metric: “There are 160,000 manholes in our system.” With that many manholes, and with the constant amount of street work and repaving required in any metro area, raising manholes to grade is a major task, performed “thousands of times annually” according to Sprague. In accordance with his belief in doing a job once, Sprague wanted a manhole raising solution that was durable and permanent. But, given the sheer scale of manhole raising in MSLSD, there was a significant opportunity to save money and time.
For both those reasons, the American Highway Products (AHP) Pivoted Turnbuckle Manhole Riser has proven to be the MSLSD preferred solution for raising manholes. “It’s a better mousetrap,” Sprague says.
Actually, the AHP riser was already in use in the district when Sprague took over the director’s position eleven years ago. “We’ve been using these risers for about fifteen years, so I knew they worked well when I started,” he says. “But I evaluated them for myself and reviewed a couple of alternatives. Once I talked to the men using them, and understood the difference the turnbuckle makes, I realized that this was the right solution for us.”
The AHP riser is a sturdy-but-flexible galvanized steel ring that incorporates a pivoted turnbuckle that gives the riser a plus or minus half-inch adjustability range. This means the riser can be slipped easily into original manhole rim, and then expanded with a Phillips screwdriver (used as a lever). The turnbuckle exerts thousands of pounds of mechanical force, seating the riser with absolute security even in rims that are worn or out of round. Most importantly, the turnbuckle can also be loosened, which is useful in St. Louis. “We looked at risers that are glued in, and decided they were no good,” Sprague explains. “Because then they’re hard to remove when we come back in a few years. It’s possible to stack the AHP risers, but I prefer not to do that. With the turnbuckle, we can just loosen the riser installed for the first paving lift, and replace it with a taller riser that will match the total height of new paving after the second lift—it’s very convenient.”
Riser heights start at 3/4-inch and increase in 1/4-inch increments. Likewise, risers can also be ordered in whatever diameters are needed, and are shipped fully assembled. Since they’re relatively lightweight and stackable, they’re easy to keep on hand. But American Highway Products also responds quickly to orders, and is able to deliver small runs of custom-sized risers within two weeks.
In addition to durability and convenience, the pivoted turnbuckle also reduces installation time. “There are a few cheaper risers, but the real cost is labor,” Sprague says. “These risers take just five minutes to install in most cases, and they last—we may have had a few fail in fifteen years, but honestly I can’t recall any examples. So for a few bucks more we’re saving a lot of time and eliminating callbacks. That makes it a better product for us.” And, for many reasons, the AHP Risers are also safer: they’re lighter, which reduces pinch and strain injuries; they don’t rattle loose and expose drivers to open manholes; and they’re quicker to install which reduces crew exposure to traffic.
And in fifteen years of heavy use in the nation’s fourth-largest sewer district, they’ve certainly proven themselves to be reliable.
Angus W. Stocking, L.S. is a licensed land surveyor who has been writing about infrastructure since 2002. He may be reached at firstname.lastname@example.org.