[Coral-List] Sedimentation traps

Dennis Hubbard dennis.hubbard at oberlin.edu
Thu May 1 09:08:35 EDT 2014

Hi Barbara:

Unfortunately, I think the only solution is to keep it out of the water in
the first place. I am guessing that this relates to sediment mining for
either construction aggregate or coastal extension. I am also guessing that
there have been few real analyses of the suitability of the sediment for
the intended purpose.

I have spent a lot of time working with these kinds of projects... and
engineers tend to think of everything as "sand". As a result, beach
nourishment projects fail and the fill is unsuitable for other intended
purposes as well. Marine sand that goes into concrete rots the rebar out
and structures collapse.... the list goes on.

So, my main objective as a consultant in years gone by was to make sure
that, however ill fated the project might be regarding where the sediment
is headed, the negative environmental impacts are minimized or eliminated.
This involves religious use of barriers to contain sediments suspended by
dredging and similar things at the site where the fill is headed. This is
difficult and I have had mixed success. However, once the fine material is
un-contained and up in the water column, there is generally just too much
of it to filter or otherwise mitigate. If you are talking about a different
issue, perhaps more information could help me/us to provide advice.



On Thu, May 1, 2014 at 1:42 AM, IUCN Barbara Gratzer <
barbaragratzer at gmail.com> wrote:

> Dear coral listers,
> I am working as a Marine Biologist in Maldives, where we are having
> repetitive problems with unchecked sand pumping.
> Different opinions on different techniques on how to minimise
> sedimentation during sand pumping were discussed lately.
> It would be great to hear your thoughts on the best technique to filter
> silt and sand from the water. Are there any studies that compare different
> techniques?
> Thank you and greetings from the Maldives,
> Barbara Gratzer MSc
> Resident Marine Biologist
> IUCN Maldives Marine Projects
> CDE -Reethi Beach Resort
> ~~~ Σ^^°> ~~~
> mobile: +960 7645346
> email: barbaragratzer at gmail.com
> email: barbara at reethibeach.com
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Dennis Hubbard
Chair, Dept of Geology-Oberlin College Oberlin OH 44074
(440) 775-8346

* "When you get on the wrong train.... every stop is the wrong stop"*
 Benjamin Stein: "*Ludes, A Ballad of the Drug and the Dream*"

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