[permaculture] Re: Pond building

Anne Erlandson aerlandson1972 at hotmail.com
Tue Sep 28 12:01:44 EDT 2004

I thought that maybe there was just a book out there that I could use to 
figure this all out for myself, but if you guys are offering your personal 
assistance then, heck, thank you!

Okay, so on this land that we've just bought we found an old failed damned 
pond about 30' wide x 20' long x 4'deep.  It has been overgrown with alders 
(probably around 80, some up to 12" in diameter) so it's been a long time 
since it's been used.  It doesn't hold water at all, there's just a gooey 
part in the center that dries out completely in the summer (the alders 
probably transpirate most of the water that accumulates).  The topsoil on 
our land is a clay silt, probably 95% silt going by the jar shake test.  
Further down, however we've found higher concentrations of clay and a 
neighbor who just had a 12' dam built found veins of nearly pure clay maybe 
6' down.  The berm of this old pond is overgrown with himalayan 

The dam is located in a gently sloping runoff in an area that gets maybe 60" 
of rain a year.  Just down hill from the dam is the neighbor's driveway so 
overflow/spillway issues are important.

We are hoping that there will be sufficient clay found to seal the pond, 
however if it doesn't hold sufficient water through the summer or dries out 
completely, we would consider alternatives such as a liner or bentonite.

I'm familiar with the issues of having different levels designed in for 
plant colonization and innoculating the pond with appropriate flora, and I 
think that I have the resources to figure that part out, but the engineering 
is what I'm worried about.  I only want to have to engineer the thing once 
(if possible) and don't want to have to try to fix it later if it leaks or 
fails catastrophically  onto the neighbor's driveway.  This same neighbor 
mentioned some other neighbor that he knew who had some earth moving 
equipment and was down on his luck and would do work for cheap.  My husband 
is eager to get this built so that it could fill up this winter and wants to 
pay as little as possible.  I'd rather wait till we can design it properly 
and get someone with pond building experience to do the work, but if we do 
go with the neighbor guy, I'd like for at least someone on site to have some 
idea of what to do even if it's just me!  :)

Any assistance is very welcome and if anyone knows of any engineering 
oriented pond design books (those ornamental garden pond books with large 
sections on how to select koi are pretty useless) which would have diagrams 
etc, that would be helpful, too.  I was a mechanical engineer in my former 
life, so I could probably make some sense of it.

Thanks again!

Anne in Seattle (and sometimes in Oakville)

>How big a pond ? ( I just got through building my second one)..... One
of the keys is that it not merely be a hole but that it have a variety
of contours, ledges, depths etc.....another is that you have either
clay or a liner, and another is that you have access to an existing
pond's water so as to inoculate your own with the right

In terms of engineering per se, is it a pond or a dam ? Will it be fed
by run off ? In this case yes, you will have to consider spill ways
etc.  and it will require a substantially more involved email :-)

Let us know,


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