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Stone stormwater diaphrams

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ACtrafficengr

Civil/Environmental
Joined
Jan 5, 2002
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1,641
Location
US
Does anyone have experience with stone filled diaphragms for stormwater retention and filtering? It is a trench along side a road or other facility filled with large washed and screened gravel (0.75-1.5 inches). The intent is runoff enters the diaphragm, particles settle out, and the water percolates into the ground through the trench bottom.

Apparently, our state Dept of Environmental Conservation, who is in charge of NPEDES/SPEDES enforcement, prefers rounded gravel since it will not compact and the voids will remain. The problem is, whenever a vehicle goes off the shoulder, the roundes stones are broadcast all over the shoulder. Luckily, it's an 8' shoulder, so not that many make it into the travel lane, but it is becoming a maintenance headache, and potentially a safety hazard as well.

Can anyone think of a way to bind the gravel together, without compromising its effectiveness as a stormwater treatment practice? I'm wondering if the hydrogel used in CU Structural Soil (TM) would work as a binder. CU Structural soil is a mixture of larged crushed aggregate, topsoil, and hydrogel binder used as a street tree planting medium.

If we used something like rairoad ballast instead of rounded river stone, would we get similar void ratios with better weight-bearing performance and more interlocking between stones?

Thanks in advance!

"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail." - Wm. Phelps Eno, ca. 1928

"I'm searching for the questions, so my answers will make sense." - Stephen Brust

 
I've worked on several projects with similar issues, and testing of various RR ballast-like materials (97% between 2- and 3/8- inch) showed 40% void ratio, which is what I would expect in rounded gravel.



 
How deep is the trench? My first thought would be to retain the specified gravel, but install a top layer of smaller crushed stone as a riding surface. One could seperate the two with a geotextile if needed.
 
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