Jean DUFAU
Personal
website
| Arcachon
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(D by google)
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A
b i z a r r e m a c h i n e
"This machine does look
threatening!
Actually it is a peaceful subsea-sled
that will embed sewage pipes off the coast, starting from La
Salie beach..."
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V
I D E O
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P
H O T O S
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P
R E
S E N T A T
I O N
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Arcachon Bay is
located on the Atlantic coast, South West of France, 80km
(50miles) from Bordeaux.
The CHARIOT is a wreck which lies off the Arcachon Bay, at
about 3 km (1.6 n.mile) from the coast.
It's a very nice dive. The wreck is a weird submarine machine, used for
sea bed works, which is there since the early 70's.
There is a shoal of hundreds of bib as
well as tenths of conger eels and large numbers of bass that make the
wreck its home .
A diver can focus
only on dense fixed fauna
and flora during the dive and that's not due to
nitrogen narcosis: the wreck is only 30
metres (98ft) deep.
Too nice to be true? Well actually there are sometimes some
difficulties: they are named les
passes.
These narrow channels are the only way to go out of the bay and reach
the sea. They can be dangerous and conditions at sea have to be
perfect to avoid any risk. Sometimes the boat has to return after a
cancelled dive, but at least there are nice beaches in the
area
to spend some good time. |
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D I
V I N G C E N T R E S
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H
I S T O R Y
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At
the beginning was a decision to
create a sewerage system around the Arcachon bay.
Inland construction site 1968 -
1971
The
first work
was to build a 30 km pipe in order to avoid the sewage of a paper
factory to be rejected into the bay. Then the sewage
were
driften to a beach called La Salie and
rejected directly to the ocean.
Offshore Underwater work
1970 - 1972
The
German company Rudolf HARMSTORF - Wasserbau GmbH was
selected in 1970.
The job was to embed a sewage pipe 5500m off the coast and to connect
a diffuser-pipe, a 200 meter long steel pipe with holes to
diffuse
the sewage water of Arcachon.
The sewage pipe made of high density polyethylene was 1.20m diameter
and embedded 2m under sea bed which is 25 to 30 metres deep.
The
embedding was based on patented Hydrojet-Injektor technology. Primarily
a water jetting device excavate a narrow but deep trench for
the pipes; moving forward it fluidized the soil while
embedding
the pipe which leaves the Injektor foot at the rear end.
The Injektor in the Arcachon project was installed on a subsea-sled now
called Le CHARIOT (see also"Some technical details").
A
long period of strong gale and a state of high sea prevented the
embedding of the sewage water pipes.Two diffuser-pipes were
broken
by storm.
Embeddment schedule was delayed.
During
the work, at least 4 serious diving accidents occurred, 2 of them were
fatal.
"Arcachon:
solidarity network for a diver...carried
by boat, a paralysed
diver in decompression chamber
to be evacuated by plane to hospital..."
So,
the diffuser pipe was not installed yet. The upcoming of smelly
foams at La Salie beach in 1971 provoked strong reactions and also
became a place for... Sunday promenade!
Finally
the construction site was predicted to end soon...
"...Harmstorf company prepared for second round..."
"La
Salie beach: it is almost finished..."
At
the begining of 1972, the end of the work is in sight. Dollar
devaluation and Mark revaluation will have an unexpected consequence
for HARMSTORF: the company got bankrupt. At the same moment the company
was involved in a big construction site in Bremen and had to face huge
financial loss
in Anchorage Alaska.
"...Harmstorf get bankrupt..."
" 
The
wharf is a pier holding the
sewage pipe
above the water
rather than below. It
is 800m long and is made of 1.50m diameter pipes. It is on
duty since April 1974.
Sewage
of towns situated around the bay are now collected after treatment and
brought to the wharf by
a 65 km pipe.
The continuous water treatment
improvements
are facing increased concerns about environment.
An interesting debate can be followed (in French) on the
Internet.
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rcachon
principe |
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S
O M E T E C H N I C A L D E T
A I L S
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The
supply vessel without water-pipes, off the coast of Arcachon.
How
the whole system works
The Injektor in the
Arcachon project was installed on a subsea-sled with more than 200
tons, similarly to the sled on the following drawing.
On
this drawing a cable is installed into the seabed, instead of water
pipes. It is however in principle the same technology.
For
more information click
Brochure from Harmstorf
company
Harmstorf family has a long history in the Diving and Salvage business.
In 1870 Friedrich Matthias Harmstorf started as the first
diver on the river Elbe near Hamburg
His son Alnwick Harmstorf, a diver too, invented
in 1926
the technology to embed cables into the seabed by the so called
Injektor with water pressure.
The grand son, Rudolf Harmstorf took over and further developed this
technology
around the world. In France, the company has burried many cables and
pipes between 1954 and 1971.
After the company went bankrupt in 1972, it was again established
by Rudolf
Harmstorf
in 1975 and worked successfully world-wide until sold to Britisch
Telecom / Cable&Wireless in 1992.
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T
h a n k s
- R
e f e r e n
c e s
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A big
"Danke" to Heinz Harmstorf for documentation, to his father Rudolf who
let us a so nice wreck.
Special thanks to Gérald
PUEL with who I made my first dive in 1998 on
what was then
called "la chenillette"
the caterpillar.
Syndicat
Intercommunal du Bassin d'Arcachon (SIBA)
Bordeaux
public library
Archives
départementale de la Gironde
Archives de
la mairie de
La Teste
SUD-OUEST
newspaper
La
Dépêche du Bassin newspaper
Web
sites
Géoportail and Earth Google
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Thanks to link this page if you use some piece of information
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| Found my English a
bit...weird ? E-mail me, I will correct ;-) @
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