Star Series Advert - (648Kb)
This is the first instalment of a six-week series that
will look at some of the major issues facing the Lake
Macquarie environment. Each week I will try to provide
an explanation to some of the common questions and sometimes
misconceptions that exist about the environmental management
of the Lake.
The first issue I have chosen to look at is concrete
- Why are concrete drainage systems considered harmful
to Lake Macquarie?
- Why is the natural alternative still the best way
of managing stormwater run-off?
We traditionally associate urban areas with neatness
and tidiness. Over history the existence of concrete
kerb and guttering, and drainage lines, has been accepted
as a feature that enhances the appearance of the areas
in which we live. It's often true that communities who
don't have kerb and guttering in their neighbourhoods
lobby Council to have it provided.
From an environmental management point-of-view, especially
in Lake Macquarie, this insistence on more concrete
and less natural vegetation is ironic.
Concrete is obviously a hard, impermeable surface.
Stormwater travels across concrete quickly and it does
not absorb into the surface. Along the way it picks
up soils, oils, pet faeces and other materials that
are part and parcel of suburban life. Even though we
have developed engineering solutions to try to filter
stormwater, concrete systems mean that stormwater reaches
the Lake at greater speed and in greater volumes.
The natural system is quite different. Vegetated drainage
lines are very effective at absorbing stormwater into
the soil, decreasing the volume and slowing the speed
at which the water travels into our waterways. The vegetation
also acts as a natural filter, removing sediments and
nutrients as well as increasing the oxygen level in
the stormwater, so that it reaches the Lake in a much
cleaner and healthier condition.
As we learn more about natural systems and the responsibilities
we assume by living on the edge of major waterways,
we are experiencing a major shift in thinking about
how we develop our urban areas.
In some areas we are now removing concrete drainage
lines and replacing them with carefully designed 'natural'
systems. This is not a complete about-face back to the
days of primitive natural earth drainage lines, but
a modern compromise that aims to balance infrastructure
needs with responsible environmental management.
The Office of the Lake Macquarie & Catchment Coordinator
does acknowledge that swales are not suitable for all
locations, such as flat or low-lying areas prone to
flooding and where there is high-density development
that requires hard engineering solutions to cope with
highly concentrated volumes of stormwater. We will continue
to develop innovative solutions that use natural systems
where possible to manage our impacts on the Lake.