WC142 MayJune 2025 - Magazine - Page 28
STORMWATER
N 2022, HAMILTON WATER
“We’vere昀椀nedourneedsforourownprogram.
embraced drone technology to enhance
Weunderstandthelimitationsandthebene昀椀ts
stormwater facility data accuracy. Partnering with Mohawk College, the initiof the technology so we can make better
ative marked a significant advancement
decisions on how we’re going to capture
in stormwater management, leveraging
innovative tools to improve efficiency and
information in the future.”
safety. This project was awarded the 2024
Water Canada Award for Stormwater
highlighting its tech-driven infrastructure.
In 2019, Hamilton saw a large reordifference between the design volume and
ganization of its stormwater portfolio. Stormwater management,
the volume they captured in measurements
operations, and maintenance were brought into the Hamilton
is the amount of sediment that’s in the
Water division. “It was a big change in the structure, and a stage of
pond. With the drone, we’re creating a
transition for our team,” says Hector Quintero, Project Manager,
bathymetric sediment surface of the entire
Stormwater Operations and Maintenance, Hamilton Water.
pond, not just the bottom, and calculating
With traditional sediment surveys, a boat travels out to the
the entire volume of the pond, so it’s more
desired location and takes on average (varies by facility size) 10
accurate than the traditional method of
measurements of the bottom of the pond using a plate attached to
applying an average depth over the entire
a survey rod. The individual putting the plate down must feel for
pond and trying to figure out the volume
the bottom, which sometimes results in compressing the sediment
of sediment,” says Wong.
and possibly giving a false bottom reading. If there is vegetation
In terms of optimizing dredging schedgrowing in the pond, that could also give a false higher reading.
ules, using the sonar gives a more accurate
“We’re only taking 10 measurements, so we compare the elevation
understanding of where the pond sits in its
of those measurements that we’ve taken to our design and/or aslife cycle. With the original method, there
built drawings, and average the sediment depth to apply across the
was an inherited level of error due to limitentire pond,” explains Amanda Wong, Stormwater Management
ed data to estimate accurate volumes. This
Technologist, Hamilton Water.
leads to a chance of intervening at one of
With its new approach, Hamilton Water suspends a sensor
the facilities too early. “We have a trigger point to dredge once
below the drone. The sensor is a single-beam sonar that measthe pond fills up to a certain amount. While our measurements
ures depth by sending a beam down in the water column and it
with the traditional survey methods were taken every year, they
bounces back off the sediment surface. The drone is outfitted with
still resulted in rough estimates and doing a bit of trend analysis,
RTK (real-time kinematic) and GNSS (global navigation satellite
but not leading to greatly accurate data.” The sonar data gives a
system) technology for the global positioning, i.e. to map/locate
better understanding of where the pond fills up with sediment,
where the measurements are taken accurately. The sonar device
and allows a better comprehension of what percentage of the
is flown approximately 2m above the water’s surface, and held in
pond volume is taken up by sediment, at the time of the survey.
place with the radar altimeter.
Safety is crucial when conducting sediment surveys. The use
“The equipment takes thousands of measurements, about one
of drones in the process allows for a much safer approach to
every 4-5 metres, as the drone follows a pre-determined flight path
data collection, as individuals are no longer being sent out on
of the pond.” This density of data points results in a better underthe water in boats, the equipment is operated from dry land.
standing of not just the bottom, but the entire underwater surface.
“The only thing that’s going in or above the water is the drone
When manually post-processing the traditional survey data, if they
and the sonar puck,” says Wong. This greatly improves health
find an outlier in one of the 10 survey measurements, that deletes
and safety for workers because they no longer need to worry
10 per cent of their data and likely would require them to go out
about lifting heavy boat and survey equipment, navigating
and re-survey. If the post-processing software from the sonar data
slippery bank slopes, leaning out over the water on a boat to
identifies one of thousands of points as an outlier, deleting one
take a measurement, etc. “The water is murky and there may
doesn’t make much of a difference. The drone-collected data therebe contaminants in the pond, so it’s great to not have to expose
fore gives much more precise data and volume estimates.
people to that,” Wong continues.
The sonar post-processing software calculates the volume of
The stormwater management program in the province of
water in the facility, as opposed to sediment depth at the bottom,
Ontario is currently undergoing a transition, driven by the
and this is compared to the designed volume of the facility. “The
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WATER C AN ADA • M AY/JUNE 2025
WAT E R C A N A D A . N E T
Hamilton Water
I
