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Nov 26, 2007 | Scarborough Sanitary District Completes Comprehensive Sewer and Manhole Rehabilitation Project
In November 2007, the Scarborough Sanitary District completed a project to rehabilitate approximately 6,950 liner
feet of interceptor sewer and 29 manholes on Black Point Road between Highland Avenue and Old Neck Road. This
interceptor sewer conveys the majority of wastewater from the Town of Scarborough to the treatment plant near
Prout's Neck. The pipes in this area range from 30-inches to 36-inches in diameter and were installed in the
early 1980's. In 2001, the District used a motorized camera device to inspect these sewer lines, and found that
the pipes were moderately deteriorated by corrosive gases commonly present in wastewater. Rather than excavate
the sewer and install new pipes, the District (in conjunction with its engineer, Earth Tech, Inc.) determined
that a more cost-effective and appropriate action would be to use a technology called "cured in place pipe"
(CIPP) to rehabilitate the existing pipes.
The CIPP sewer rehabilitation was completed by Insituform Technologies, Inc., of Charlton, Massachusetts in October
and early November 2007. CIPP technology inserts a liner (in the case of this project, typically around 600
feet in length) into the existing sewer pipe during a process called "inversion". The liner is made of
industrial-grade felt and is impregnated with resin materials that harden when exposed to elevated temperatures.
The thickness of the liners on this project was determined based on the depth of the pipe and the weight of soil
and water above the pipe. A typical 600-foot liner used in this rehabilitation project weighed approximately
30,000 pounds. Once the liner was positioned in the sewer pipe, steam was forced into the liner to cause it to
adhere to the sewer pipe. The steam "cured" the liner, or to caused it to harden completely, forming a "pipe
within a pipe". The cured liner has a smoother surface than the original pipe, and will not corrode over time.
While the liner was installed, wastewater that normally flowed through the pipe was diverted so as not to interfere
with the curing process. This was accomplished by a company called Rain for Rent by the use of large bypass pumps
and piping, which were visible on the shoulder of Black Point Road. Flow-through ramps maintained access by
residents and emergency response vehicles to driveways and side streets. Traffic control and flaggers maintained
one-way traffic on the road when the contractor was working.
Residents were notified in advance of when the section of sewer impacting their home would be rehabilitated - a
week ahead of time, and again 24-hours ahead of time- by Insituform and by a representative from Earth Tech.
While a liner was curing, residents connected to that segment of the sewer were asked to minimize their water
usage, since wastewater from their home's service connection was temporarily blocked from entering the pipe by
the liner itself. As soon as the liner had fully hardened, Insituform's crew opened, or re-established, the
sewer connection (allowing the resident's wastewater back into the rehabilitated pipe) and sealed the joint
between the service connection and the rehabilitated sewer pipe.
After the sewer lines in the project were rehabilitated, the manholes received repairs and coatings that will
help protect them from additional corrosion, as well. Four key manholes received a monolithic epoxy rehabilitation
system, which involved a heavy-duty epoxy material that is resistant to corrosion and structurally reinforces
the manholes; this was completed by A&W Maintenance using Warren Environmental System, Inc., products. The
remaining manholes received repairs and a cement-based coating by a company called National Water Main. These
repairs and coating will protect the manhole structure from additional deterioration.
The District would like to thank residents in the project area for their patience, and the people who drive on
this road often for respecting traffic control devices and personnel. We would also like to thank all Town
departments and emergency response services for their cooperation.
Insituform Technologies inverting a 36-inch diameter CIPP liner on October 10, 2007.
Bypass pumping equipment and traffic control in front of Black Point Cemetery on October 16, 2007.
Photograph within rehabilitated 36-inch pipe.
Manhole No. 22 at Clay Pits Road after epoxy rehabilitation.
Manhole No. 27 at Fogg Road before (left) and after (right) epoxy rehabilitation.
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