Author: Professor, Dr. Dietrich Stein - TrenchlessOnline

step of cutting in keyways must be performed to ensure
proper adhesion of the material to all of the walls.The crew
cut quarter-inch deep keyways on a 30-degree angle
approximately every foot, both horizontally and vertically,
inside the entire square area of each of the structure.
Before spraying began,using a 7 million BTU jet heater,the
crew heated each structure, eliminating any residual moisture
from the concrete surface.This took approximately 40
minutes. In the spray rig, a bigger heater unit had been
installed to heat the Spraywall material, while the 75 ft of
feeder lines that run from the material containers and heating/mixing
equipment on the rig to the specially designed
Graco spray gun were wrapped with pipe foam insulation to
help keep the material at the proper constant temperature.
Typically, the spray application will commence at the bottom
of the structure with the sprayer applying the material
to one side of the structure from the manhole bench, turning
around, applying it to the opposite side and working
upward. In this case, Team Elmers had to approach the
application a different way. “Because of the depth and
groundwater infiltration, we started at the top and worked
our way to the bottom,” Prescott explains.“That way, if we
did encounter a leak, we weren’t chasing it as the top was
already sealed so it wouldn’t have anywhere to go.” An
application of 250 to 300 mils thick was applied to all surfaces
of the structures. Each manhole required approximately
four to five hours of spray time with preparation for
each taking approximately one to two days each.
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Although the Region of Peel was skeptical about the technology
and it being able to provide the strength and structural
integrity officials were looking for, Team Elmers successfully
demonstrated the benefits and effectiveness of
spray-applied polyurethane technology under less than
ideal conditions.The budget for the project was approximately
$240,000. The client was so pleased with the outcome
of this solution that it is now being considered for use
in several other rehabilitation projects within its system.
Moving to Points South…
Manhole rehabilitation in warmer,coastal climates brings
its own set of challenges. National Pipe Services (NPS), the
Sprayroq certified partner for Florida, was tasked with performing
sewer system rehabilitation for the affluent vacation
resort island of Long Boat Key.
Just like the Team Elmers project, weather conditions can
greatly affect how a project is managed and approached. In
the case of Long Boat Key, extremely high water tables, tidal
patterns,daily rains and extremely high temperatures were all
important considerations in ensuring a successful outcome.
“Long Boat Key is extremely proactive when it comes to
the management and maintenance of its infrastructure system.To
help eliminate extreme [inflow-and-infiltration] levels
that were impacting the quality of wastewater treatment
in the community,[city officials] knew one good spot
to start was in their manholes and lift stations,” says NPS
vice president Ron Wilkes.
September 2007 TRENCHLESS TECHNOLOGY 27