Some of you may have seen a project that occurred along Co.
Rd. 4 near the Conservation Club. Public
Works, along with a contractor, were accomplishing some maintenance on Lift
Station Number 1. This lift station
takes all of the wastewater in the city and pushes it through a forcemain to
the Wastewater Treatment Plant. The
project involved the replacement of two base elbows and two check valves.
Lift stations are built with two pumps that alternate
pumping which gives us some redundancy in the system. If one pump has problems the other pump can
be used while the pump is repaired or replaced.
With the two pumps you have two sewer lines that deliver wastewater to
the forcemain. Each line required the
replacement of the base elbow. These base
elbow pipes direct the flow from the pump to the forcemain. Both lift pumps had
to be taken out of operation to work in a manhole that would otherwise be
filled with sewage.
The sewer system was installed in 1976. Since that time there has been some
replacement of components. In particular,
the lift station started out with smaller horsepower pumps and as they were
replaced, larger pumps were installed.
The additional stress on these elbows from larger pumps eventually
created wear as the elbow size had not been increased with the larger
pumps. Erosion of the pipes created
leakage in the seals of these base elbows.
This not only leads to lower efficiency it also leads to eventual
failure of the piping system.
These base elbows were replaced and enlarged from a 4 inch
to a 6 inch pipe. When you have a forcemain
the system needs to have check valves.
These allow for a one way flow in the pipe. Each of the two lines has a check valve. These were also replaced as long as the system
was under repair.
Accomplishing this took a good deal of effort. As the lift station feeds the forcemain and
all wastewater goes through this lift station a temporary bypass pipe needed to
be installed. Taking the lift station
out of operation meant we needed to have an auxiliary pump of sufficient size
to act as a replacement lift station.
The sewer main had to be capped at the next upstream manhole so flow was
stopped before getting to this lift station, allowing for work to occur there. The auxiliary pump was then hooked up to that
manhole and connected to the bypass pipe.
The main lift station manhole was then pumped out completely so repair
work could be completed. Both pumps were
removed so that the base elbows could be replaced. With the elbows replaced and pumps
reinstalled the bypass was removed and the lift station was put back in
service.
The two check valves were next. With the lift station using one of the pumps the
other sewer main saw the replacement of the check valve. Once the replacement of that line was done
the process was repeated with the other sewer main, installing a check valve
there. With that installation the
project was completed.
As stated this may not seem to be a large project. It was however fairly complex and costly to
accomplish. The project went as well as
could be expected. Working in sewer manholes
replacing parts that are 40 years old took some expertise and patience but it
is now in place for hopefully another 40 years.
