Like many municipalities in the northern Midwestern states, the town of Sheboygan, Wis., faced chal- lenges in keeping at-grade manholes in good repair.
Snow-covered roads, freezing temperatures, and the use of
salt and ice-melting compounds throughout the winters took
their toll on the concrete rings that brought manhole covers
up to road grade. Cracked and crumbling concrete caused
leaks, which in turn led to cracks in the road and potholes as
winters wore on. This created the need to make frequent repairs when spring and summer arrived — which meant traffic
tie-ups on busy public roads.
“It used to take two or three days to get the road back in
operation,” noted Bill Blashka, director of public works for the
town of Sheboygan. “The biggest problem was needing to
use heavy equipment to replace the concrete rings. We had
to put 12 to 16 inches of concrete rings on, and we would
get the rings in thicker sections so we didn’t have all the joints
where you need mortar because those can leak.”
Two strong workers could lift and maneuver a slim con-
crete ring but the ones that were a foot thick or more were
too heavy for crewmembers to carry. Some workers had even
been hit by moving or falling rings and suffered injuries.
“We needed heavy machinery to move the rings,” said
Blashka. “So then we had a big machine at a manhole repair
— and people could still get hurt. Meanwhile, the machines
messed up traffic.”
Concrete rings require layers of mortar between them,
which need time to set up and cure before workers can com-
plete the installation and backfill the manhole. This means
that a manhole repair job can stand open for days until crew
can backfill and get their equipment off the roads.
Meanwhile, deteriorating mortar between layers of concrete and cracked concrete rings create issues with inflow and
infiltration (I&I). Cracks at or near grade allow clear water to
enter the sewer system from the road, while crumbling mortar below grade permits groundwater to seep into the sewer
So when Blashka heard that Cretex Specialty Products in
nearby Waukesha had a new product for manhole grade adjustment, he took an immediate interest.
The PRO-RING™ Manhole Grade Adjustment System is
made from ARPRO® expanded polypropylene (EPP), the
engineered polymer that has been in use in the automotive
Snow-covered roads, freezing temperatures, and the use of salt and
ice-melting compounds during winter take their toll on the concrete rings
that bring manhole covers up to road grade.
With the PRO-RING system, one worker can easily lift even the largest
rings, eliminating the need for heavy machinery to lift and move rings
into place on the manhole.