Bridge to Bridge
Caches
10 kilometres separates the 2 bridges on Old Coast Road that
provide access to the island created by the Dawesville Cut.
This is a series of caches accessible from the bike paths on either
side of Old Coast Road between the bridges (and a little bit
beyond). The caches vary from nanos to ammo boxes and all
things in between, whatever is appropriate to the location.
There are also a number of other caches easily accessible from
these bikes path so seek them out also.
Dawesville Cut
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Dawesville Channel
looking east
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Dawesville Channel looking
west to the coast
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The Dawesville Cut (or channel) was constructed to alleviate an
environmental problem which had developed where much of the
136 km², two metre deep estuarine system had become highly
loaded with artificial nutrients. The adjoining estuaries' ability
to support the natural flora and fauna had become seriously
degraded and the smell of rotting algae, particularly during the
summer months had caused increasing complaints from residents.
Stocks of the normally abundant fish and crabs had become depleted
and recreational use was impacted. The deteriorating environmental
situation became a major political and environmental issue for the
Government of Western Australia during the mid 1980s.
For over twenty years, government and agricultural industry
groups battled with the issue, largely unsuccessfully. The scale of
the problems seemed daunting and because there seemed to be
numerous causes, and most stakeholders blamed each other. As a
result, the problem got worse and the issue became politicised.
The solution was proposed after a number of studies including
those of environmental scientists Professor Arthur McComb
and Ernest Hodgkin who identified that the cause of the blooms were
the phosphorus load in the water which had come from run-off
associated with agricultural and industrial practices in the
catchment area. They formed the conclusion that altered procedures
for applying fertiliser would improve the estuary, but that a
dramatic improvement in the short-term would only be achieved by
cutting a new channel to the ocean.
The proposed channel would increase water exchange between the
estuary and the ocean to facilitate the flushing of nutrients from
the estuary out to sea, and would increase the salinity to levels
that would restrict germination and growth of the blue-green algae.
A daily tidal movement of about 1 metre assisted the flushing
process.
After several years of deliberations, a decision was made to
build the channel at an estimated cost of $37 million. The
channel's construction commenced in 1990 and was completed in April
1994. It is about 2.5 kilometres long, 200 metres wide and between
6 and 6.5 metres deep.
Construction involved the excavation of about 4.5 million cubic
metres of material.
In addition to the excavation work, construction of breakwaters,
training walls, a bridge and installation of a sand bypassing
system was undertaken.
The channel is spanned by the four lane Port Bouvard Bridge
which forms part of the Old Coast Road which carries traffic
between Perth and the southern coastal townships. Approximately
40,000 vehicles per day use the road. Major residential canal
developments have been constructed off the channel including the
suburb of Wannanup and a golf course.
Since its opening in 1994 no blue-green algal blooms have
occurred.
Information obtained from Wikipedia
This
Cache
This cache is on the eastern walkway under the bridge and is
accessible in a wheelchair. The GPS was showing max 10m accuracy
when we set this as its under the roadway. If all else fails use
the hint.
The cache is a small container with room for small
trackables. It is secured to the bridge so won't fall into
the water but any loose items in the container may do so - so take
care.
There is a FTF signal micro coin for the FTF. and one of our
stretchy lizards as an initial swap item.
Please replace the cache carefully to preserve the hide and don't
leave anything dangling.
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FTF Congratulations
to
Urch
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