Glen Walter Sewage Collection System was built to service 1080
customers in 1989. At the time the population was 850 but by 1995
the sewage treatment plant had already reached capacity. Shawn Killoran took over the Operations Manger position in 1999 and, along
with the Mayor and Council, he immediately had concerns about the
Township started by video taping all of the lines in the collection
system. The pipe work was found to be in good condition so
significant infiltration was unlikely. Shawn realized he had to
rethink the approach and find a way to leverage technology. He
decided to monitor flow in high volume areas within the collection
system. The Township selected Stingray
Level-Velocity Loggers from Greyline Instruments because they
are portable, work in partially filled pipes, and enable technicians
to retrieve wastewater flow data without entering manholes.
I&I study of the Glen Walter Sewage Collection was conducted from May 16th
to June 9th 2006. The instrument’s ultrasonic sensors
were installed in 7 different manholes for periods of 3 to 5 days.
To capture detailed flow information the Township set the Stingrays
to take readings at 10 second intervals. To deploy each unit, a
township technician selected a manhole location, attached a
stainless steel bracket in the influent pipe, then mounted the
sealed, ultrasonic sensor into it. The technician connected the
sensor cable to the watertight electronic logging unit and hung it
inside the manhole. The logger recorded the date and time, water
level, velocity and temperature.
conduct the study the Township recorded weather conditions on a
daily basis in the Glen Walter Collection log book and the number of
homes upstream of the flow monitors were also noted. When a Stingray
was removed from a specific manhole, the information was transferred
to Greyline Logger software and a graph was created which displayed
the total flow for that specific area. At the end of the survey
Shawn prepared a flow monitoring report for the Mayor and council on
high volume areas within the collection system.
average of one cubic meter a day per household was used as a guide
for the amount of water used in a 24 hour time interval. Locations
monitored by Stingray Level Velocity Loggers recorded flow rates
15-70% higher than statistical flows. The loggers captured spikes in
flow that matched typical run times from domestic sump pumps.
Because the Stingray is able to monitor water temperature, Shawn
also observed corresponding temperature drops matching the pump
cycles. The evidence was clear: residents were connecting sump pumps
to the municipal collection system.
Municipal agents went door-to-door informing residents that improper
sump pump connections had been identified. They requested that any
sump or eves trough discharges be disconnected from the municipal
system. Shawn reported that “after the flow survey we observed a
reduction in influent at the sewage treatment plant”. Since the Glen
Walter study, the Greyline Stingrays continue to be used to measure
flow in other applications in the Township of South Glengarry.