storm_sewer_system_brochure

Here’s how
it all flows . . .
Thousands of feet above the surface
of the earth, water molecules
change from vapour to liquid in
a storm cloud. The water falls to
earth as rain. This is where our
story begins…
Rain and Runoff
When it rains, especially when
it rains hard, there will be water
running from your property onto
the road. Stormwater is the water
from rainstorms or melting snow
that goes into the catchbasins
in the road and then through an
underground pipe system to the river. It is
The City of Calgary’s responsibility to control
the volume and the quality of stormwater
that is released into the river.
Collection System
The collection system for
stormwater includes
catchbasins (stormdrains);
an underground pipe
system; an overland
conveyance system;
and ponds.
The catchbasins are
the main access point
for water to get into
the underground pipe
system. The metal grates that
can be seen at the edge of
paved roads are only a portion
of the catchbasin structure.
Under the sidewalks is a barrel
that collects the water. The
barrel is attached to a pipe
which allows the water to be
whisked away. Sometimes the
catchbasins can be plugged with
hail or debris such as leaves
and sticks making it more difficult
and longer for the water to drain away.
The overland conveyance system
includes the eavestroughs on buildings,
concrete gutters that can be found
behind houses in newer areas, grass
swales and the roads or lanes. Instead
of having the water directed to a
catchbasin right away, the water is
kept above ground until it reaches
the nearest catchbasin.
The underground pipe system
consists of different size pipes; the
smaller pipes feed into the larger pipes
that are closest to the river. These
pipes direct water to the river by
way of gravity and some are big
enough to drive a car though.
CATCH
BASIN
MANHOLE
OUTFALL
WET POND
CATCH
BASIN
2) A wet pond
always has water
in it but the water
MANHOLE
will get much
deeper during a
storm. The wet
pond can help to clean
the water that comes off
the roads because it allows
the water to slow down, at which
point the heavy dirt and garbage will
settle to the bottom. Cleaner water will
then drain out of the wet pond when the
pipes downstream aren’t full of water.
3) A wetland is similar to a marsh or
bog: it contains plants and the water
is quite shallow before a storm. The
plants that grow in wetlands filter
out the fertilizers and pesticides
that some people put on their
lawns. A wetland can clean
the water better than a
wet pond.
Outfalls
The outfalls are the exit
points from the pipe
system to the river.
There are more
than 300
of them in
Calgary.
There are three different
types of ponds that can
collect water. Each serve
different functions:
1) A dry pond is dry 90
percent of the time and
can have playing fields
in it. Dry ponds fill
with water very
quickly in heavy
downpours and can
take as long as 24 hours
to drain once the rain
stops. It is important
to stay out of dry
ponds during
and after
a rainstorm.
OUTFALL
Your
responsibility
Only a small portion
of the catchbasins drain
through a wetpond
or wetland so there is a
responsibility for all of us to
safeguard the rivers. There are
ways to improve the quality of
stormwater such as regularly washing
your car at car washes, limiting the use
of fertilizers and pesticides on your
lawn, and by sweeping the
dirt off the sidewalks
and driveways onto the
grass instead of the road.
By allowing only clean water into
the catchbasins, we can ensure that the
fish, ducks and the other wildlife that
use the Bow River remain healthy.
Our water is a finite resource: it
is used over and over again
and it’s our responsibility
to preserve its
cleanliness.
THE CITY OF CALGARY STORMWATER SYSTEM