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permeability estimate from fines content

permeability estimate from fines content

permeability estimate from fines content

(OP)
I am trying to come up with a rough seepage estimate for a wet detention pond in which the design normal water level is about 1.5 feet below the groundwater level.  

The site is mostly clayey sand.  

I used to have a correlation between fines content and permeability, but I just moved offices and can't find anything.  

This is one of those things that shouldn't cause a problem but I need data to bring to the permitting agency.

Does anyone know of a rough correlation between k and fines for clayey (or silty) sands?

RE: permeability estimate from fines content

jgailla....Sowers has a table in his book for reasonable correlation.  Das probably does as well.  Mine are packed up or I'd check them for you.  In general, clean sands will be in 10^-3 range, while clays will be in the 10^-7 range.  Clayey sands will generally be in the 10^-5 range (+/-).

Here's the relationship given in a military publication...http://www.usace.army.mil/publications/eng-manuals/em1110-2-1901/c-2.pdf

Check the figure on page 10.

RE: permeability estimate from fines content

(OP)
Thanks Ron.  This is exactly what I was looking for.  I had Das and Budhu, but the ranges didn't address sand-clay mixtures.

RE: permeability estimate from fines content

Check out Terzaghi Peck and Mesri - they report, from recollection, new correlations of material permeabilities after Kenney.

RE: permeability estimate from fines content

For clean sands one can use Hazen's equation:
k = C.(D10)^2
D10 = diameter for 10% finer
You can use an average value for C, C = 1.
If you take D10 in mm, your k value will come out as cm/s.

If you have even small amount of fines (clays/silts) this may reduce your k dramatically. So Hazen's k value may be your upper boundary since you have clayey sand.

I agree with Ron. 10^-5 cm/s is a good approximation for clayey sand. For fine sands, mixtures of sand, silt and clay I would say the range k = 10^-4 to 10^-6 cm/s.

hope this helps

RE: permeability estimate from fines content

NHSlide - if you check out later studies (i.e., Kenney), they are now arguing that using the D5 size is more appropriate.  The Hazen's coefficient was really only for clean medium sand.

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