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2010 11th Annual Awards of Excellence in Consulting Engineering
Award of Excellence – Municipal & Water Technology
KGS Acres Ltd.
The Pointe du Bois wastewater collection system renewal project
The Manitoba Hydro community of Pointe du Bois located
in the Whiteshell Provincial Park services Manitoba Hydro’s
oldest hydro generating stations: Pointe du Bois and Slave
Falls. The community’s original infrastructure was built
during the construction of the Pointe du Bois Generating
Station, sometime between 1909 and 1926. Among the aging
infrastructure was a gravity wastewater sewer system fabricated
from vitrified clay pipe that remained in service until
very recently.
Despite several rehabilitative upgrades, the system’s deteriorated
pipes and manholes continued to allow excessive
groundwater infiltration that overloaded the community’s
wastewater treatment plant during spring melt periods and
heavy rain events.
Manitoba Hydro retained KGS Acres to develop a
permanent solution that managed environmental impact,
while minimizing capital costs and maintenance. KGS Acres’
services included monitoring flows, diagnosing the problem,
developing remedial alternatives, detailed designing of the
preferred alternative and contract administration.
KGS Acres implemented a number of unique applications
using modern engineering technologies, allowing the design
team to efficiently diagnose the problem and develop an efficient,
yet cost-effective design. These technologies included
survey-grade GPS supplemented by a Light Detection and
Ranging (LiDAR) survey of Pointe du Bois and the immediate
surrounding region. The data produced from both ground
surveys were used to develop a digital terrain model (DTM)
of the existing topography using AutoDesk’s Land Development
Desktop design software. KGS Acres also implemented
ultrasonic flowmeters, installed in strategic locations within
the existing system, to identify the sections that were experiencing
extraneous flows.
KGS Acres’ unique solution retrofitted the existing gravity
sewer by incorporating it as a protective conduit and
alignment for the new high-density polyethylene which was
installed within the old clay pipe. The system was converted
from a gravity system to a low-pressure-sewer system. To
provide the low pressure, each residence and building connected
to the system was fitted with a 1-HP progressing cavity
grinder pump housed within a 485-L capacity grinder pit.
A total of 1,046 metres of new mainline piping was installed.
Since completion of the project, flows have been stable and
overall wastewater flows to the system have been reduced
by 90%, well within license requirements.
The project, located in the Whiteshell Provincial Park,
inherently adopted a low tolerance for environmental
impact. The retrofit project was a unique and innovative solution
that eliminated hydraulic overloading and minimized
the human ‘footprint’ on the naturally pristine location. The
construction technique itself was considered ‘green,’ requiring
minimal excavation to install the new system and also reusing
the old pipe network. The construction method also allowed
the old wastewater collection system to be kept ‘live’ during
construction, thereby minimizing interruptions to Manitoba
Hydro’s day-to-day operations at Pointe du Bois.
The final construction costs were still below the original
contract price even after implementing several value-added
design changes during the construction phase. Ultimately, KGS
Acres delivered the project within Manitoba Hydro’s timeframe
and under the original construction budget.
Pointe du Bois is now home to Manitoba’s largest grinderpump
equipped low pressure sewer system.
Judges’ comments
This project was chosen because installing
a new low-pressure sewer system inside the
existing deteriorated sewer system was a
unique solution. It dealt with the problem
of groundwater infiltration and dramatically
reduced flows at the wastewater treatment
plant. Construction was less expensive with
reduced disruption and with reduced risk of
damage to other buried utilities.
page 38 | Consulting Engineers of Manitoba Awards of Excellence
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