[GSBN] Help us help in Haiti

[Bruce King]

Thanks to all who have replied.  Tim Owen-Kennedy (with whom I'm  
working in Haiti) advises a good settling pond left to dry, then pull  
off the surface clay chips that curl into the distinctive pattern.   
Makes sense, but takes a lot of time, especially in the rainy tropics.

What I've seen and heard so far essentially describes extensive  
settling, by gravity or machine, to separate the tiny silt particles  
from the teensy weensy clay particles.  I guess I could imagine two or  
three adjacent settling ponds on successfully lower grades, such that  
you could siphon the surface stuff from the first into the second,  
then again to the third, thus getting finer and finer particle sizes.

To answer Derek's questions:  we'll be dealing with hundreds of pounds  
at a time, no machinery of any sort other than human powered.  Soils  
around Haiti, as everywhere, vary, and we're not trying to quantify  
particle gradations.  We just want a robust system that anyone can use  
to "improve" a particular soil to the point where it will pass the  
ribbon or ball tests.

That's our challenge.  All your help and comments are very much  
appreciated.

Bruce King, PE
Director of EBNet
Ecological Building Network
the art and science of building well
bruce at ecobuildnetwork.org
PO Box 6397
San Rafael, CA 94903 USA
(415) 987-7271
follow us on Twitter: @EBNetwork

On Jan 3, 2011, at 12:46 PM, Derek Roff wrote:

> Hi, Bruce,
>
> I appreciate your humor, and your New Year's salutations.  Sign me  
> up for the Hawaii Silt Vacation Sweepstakes.
>
> Can you say more about the volume and efficiency that you need in  
> the system?  That would help us propose ideas that would be useful  
> to you.  For example, are you trying to process a hundred pounds of  
> soil, a thousand, or ten thousand per day?
>
> What amount of "waste" soil is acceptable.  I'm guessing that your  
> goal is to get at the clay, and that the silt will be a unimportant  
> byproduct.  Is that correct?  In wondering about efficiency, I'm  
> thinking along these lines:  If the soil is naturally 20% clay and  
> 30% silt, then the optimum system would extract 2 pounds of clay  
> from each ten pounds of soil.  What if you could only extract 1  
> pound of clay from each ten pounds, but you got pretty good purity  
> of that clay.  Would that be acceptable?  Alternatively, what if a  
> process gave you 4 pounds of product from each 10 pounds of soil,  
> but that product was 50% clay?  Would that be useful?  If not, what  
> sort of purity percentage would be worthwhile?
>
> Does this process need to be human-powered, or could electrical or  
> gasoline motors be a part of the machinery?  What is your "easy  
> enough" process for separating the sand and gravel?  Perhaps the  
> clay separation process could be added to the sand/gravel separation  
> phase.
>
> I have some ideas, and have done some small-scale tests, but I'm not  
> sure they would fit your needs.
>
> Dere-"particulate"-lict
>
> Derek Roff
> Language Learning Center
> Ortega Hall 129, MSC03-2100
> University of New Mexico
> Albuquerque, NM 87131-0001
> 505/277-7368, fax 505/277-3885
> Internet: derek at unm.edu
>
>
> --On Sunday, January 2, 2011 1:46 PM -0800 Bruce King <bruce at ecobuildnetwork.org 
> > wrote:
>
>> Happy New Year, baleheads.
>>
>> We have a lot of soil in Haiti that is rich in both clay and silt.
>> Easy enough to separate the sand and gravel, but we haven't figured
>> out a good way to separate silt from clay.  So far we've tried:
>>
>> 1) Asking nicely
>> 2) Offering every silt particle a chance to win a Hawaiian dream
>> vacation if it separates itself from the clay
>> 3) Telling the silt that if it just leaves quietly now, no one will
>> get hurt
>> and, getting really hardball,
>> 4) Hanging a few "example particles" of silt by their silica
>> crystals  in the public square, with warning notes attached.
>>
>> Still no luck!  Anyone have a good low-tech field method for
>> separation?
>>
>> Thanks,
>>
>> Bruce "Hang 'em High!" King
>
>
> Derek Roff
> Language Learning Center
> Ortega Hall 129, MSC03-2100
> University of New Mexico
> Albuquerque, NM 87131-0001
> 505/277-7368, fax 505/277-3885
> Internet: derek at unm.edu
>
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