<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">This is kind of a random topic…but has anyone from this list explored the use of natural-building type mixes as a multi-functional substitute for concrete in stone retaining walls? <div><br></div><div>My application: stone walls to hold landscape terraces designed to infiltrate stormwater. There is up to 6" of standing water on top of the terraces. (Note: I realize this contravenes the usual convention to make the walls porous, but people make water tanks with gravity stone walls that don't topple and we seem to be OK on toppling so far. I'm going with 25% lean in the walls.)<div><br></div><div>Functions: </div><div><ul><li>behind the wall: slow the movement of water through the wall</li><li>under the wall: support the stones with gravel if water finds a way under the wall (usually gravel w/o clay is used. The idea is that the gravel would stay if the clay is flushed away by a leak.</li><li>extending over the previous soil surface behind the wall: discourage gophers and water from tunneling under the wall. (Gophers are allegedly stopped by 1" gravel)</li><li>attract roots to infiltrate the mix and make a long-term, living reinforcing mesh around the gravel and stones….similar to those flying rocks one sees held by roots on the sides of eroded creek banks</li></ul></div><div><br></div><div> Here's my draft specification:<div><br></div><div><br></div><div><img id="b0481875-3e87-4fa9-a032-6f9682700861" height="317" width="964" apple-width="yes" apple-height="yes" src="cid:81C00674-3297-47A2-9813-7826766FBB48@impulse.net"></div><div><br></div><div>
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<!--StartFragment--><p class="MsoNormal" style="margin-bottom:0in;margin-bottom:.0001pt;mso-pagination:
none;mso-layout-grid-align:none;text-autospace:none"><b><span style="color: rgb(16, 73, 188); ">Stormwater Terrace
Retaining Wall Construction Specifications<o:p></o:p></span></b></p><p class="MsoNormal" style="margin-bottom:0in;margin-bottom:.0001pt;mso-pagination:
none;mso-layout-grid-align:none;text-autospace:none"><b><span style="color: rgb(16, 73, 188); "> </span></b></p><p class="MsoNormal" style="margin-bottom:0in;margin-bottom:.0001pt;mso-pagination:
none;mso-layout-grid-align:none;text-autospace:none"><b><span style="color: rgb(16, 73, 188); ">Under the wall:
bigger than 1" minus gravel (every size from say, 1.5 or 2"
down) mixed with clay(just enough to fill spaces between gravel, no
more; weight of stones should be bearing on gravel not clay) and a small
amount (2-%?) of slow release fertilizer/ compost. </span></b><span style="color: rgb(16, 73, 188); ">Mix
to the consistency of concrete and use like concrete under the wall. Can also
add chips from working stones. Make sure spaces between the large gravel and
chips is too small for gophers to pass. SHould be something like 1-4"
thick. Predicted effects: <o:p></o:p></span></p><div style="margin: 0in 0in 0.0001pt 0.5in; text-indent: -0.5in; "><!--[if !supportLists]--><span style="color: rgb(16, 73, 188); ">•<span style="font-size: 7pt; font-family: 'Times New Roman'; ">
</span></span><!--[endif]--><span style="color: rgb(16, 73, 188); ">Gravel provides initial and permanent support for the
stone, filling any voids between the stone and earth. <o:p></o:p></span></div><div style="margin: 0in 0in 0.0001pt 0.5in; text-indent: -0.5in; "><!--[if !supportLists]--><span style="color: rgb(16, 73, 188); ">•<span style="font-size: 7pt; font-family: 'Times New Roman'; ">
</span></span><!--[endif]--><span style="color: rgb(16, 73, 188); ">Clay stops water from going under the wall.<o:p></o:p></span></div><div style="margin: 0in 0in 0.0001pt 0.5in; text-indent: -0.5in; "><!--[if !supportLists]--><span style="color: rgb(16, 73, 188); ">•<span style="font-size: 7pt; font-family: 'Times New Roman'; ">
</span></span><!--[endif]--><span style="color: rgb(16, 73, 188); ">Large gravel (over 1") blocks gophers (too big
for them to move, allegedly). Spaces between 1" gravel too small for
gophers to pass.<o:p></o:p></span></div><div style="margin: 0in 0in 0.0001pt 0.5in; text-indent: -0.5in; "><!--[if !supportLists]--><span style="color: rgb(16, 73, 188); ">•<span style="font-size: 7pt; font-family: 'Times New Roman'; ">
</span></span><!--[endif]--><span style="color: rgb(16, 73, 188); ">Roots will find the compost/ fertilizer and colonize
the clay, gradually replacing the compost mass with root mass. <i>This root
mass will be like living rebar/ mesh that holds the whole thing
together for eternity. </i><o:p></o:p></span></div><div style="margin: 0in 0in 0.0001pt 0.5in; text-indent: -0.5in; "><!--[if !supportLists]--><span style="color: rgb(16, 73, 188); ">•<span style="font-size: 7pt; font-family: 'Times New Roman'; ">
</span></span><!--[endif]--><span style="color: rgb(16, 73, 188); ">If there is a leak under the wall, the clay, sand and
small gravel can wash through, leaving the large gravel to support the wall so
it doesn't collapse into a void.<o:p></o:p></span></div><p class="MsoNormal" style="margin-bottom:0in;margin-bottom:.0001pt;mso-pagination:
none;mso-layout-grid-align:none;text-autospace:none"><span style="color: rgb(16, 73, 188); "> </span></p><p class="MsoNormal" style="margin-bottom:0in;margin-bottom:.0001pt;mso-pagination:
none;mso-layout-grid-align:none;text-autospace:none"><span style="color: rgb(16, 73, 188); ">On the surface of the dirt
behind the wall; The same mix, as gopher, water barrier, extending along
the ground 6"-24"<o:p></o:p></span></p><p class="MsoNormal" style="margin-bottom:0in;margin-bottom:.0001pt;mso-pagination:
none;mso-layout-grid-align:none;text-autospace:none"><span style="color: rgb(16, 73, 188); "> </span></p><p class="MsoNormal" style="margin-bottom:0in;margin-bottom:.0001pt;mso-pagination:
none;mso-layout-grid-align:none;text-autospace:none"><span style="color: rgb(16, 73, 188); "> </span></p><p class="MsoNormal" style="margin-bottom:0in;margin-bottom:.0001pt;mso-pagination:
none;mso-layout-grid-align:none;text-autospace:none"><span style="color: rgb(16, 73, 188); ">On the back side of the
wall </span>It
will hold if it's sandwiched between the soil and the wall<span style="color:#1049BC">: The same mix or substitute sand for gravel, as a
water barrier (presumed that gophers won't go through the wall)<o:p></o:p></span></p><p class="MsoNormal" style="margin-bottom:0in;margin-bottom:.0001pt;mso-pagination:
none;mso-layout-grid-align:none;text-autospace:none"><span style="color: rgb(16, 73, 188); "> </span></p><p class="MsoNormal" style="margin-bottom:0in;margin-bottom:.0001pt;mso-pagination:
none;mso-layout-grid-align:none;text-autospace:none"><span style="color: rgb(16, 73, 188); ">In between rocks of the
wall: The same mix, with gravel sized to the space between the rocks
(might be more like 3/4" than 1.5")<o:p></o:p></span></p><p class="MsoNormal" style="margin-bottom:0in;margin-bottom:.0001pt;mso-pagination:
none;mso-layout-grid-align:none;text-autospace:none"><span style="color: rgb(16, 73, 188); "> </span></p><p class="MsoNormal" style="margin-bottom:0in;margin-bottom:.0001pt;mso-pagination:
none;mso-layout-grid-align:none;text-autospace:none"><span style="color: rgb(16, 73, 188); ">In between rocks on the
top course of the wall, above the soil level: Cement stucco, to keep
water from going between the rocks. <o:p></o:p></span></p><p class="MsoNormal" style="margin-bottom:0in;margin-bottom:.0001pt;mso-pagination:
none;mso-layout-grid-align:none;text-autospace:none"><span style="color: rgb(16, 73, 188); "> </span></p><p class="MsoNormal" style="margin-bottom:0in;margin-bottom:.0001pt;mso-pagination:
none;mso-layout-grid-align:none;text-autospace:none"><span style="color: rgb(16, 73, 188); ">In low spaces on top of
the wall: Small decorative rocks or shells mortared in place to maintain the
line for the top water level.<o:p></o:p></span></p><p class="MsoNormal" style="margin-bottom:0in;margin-bottom:.0001pt;mso-pagination:
none;mso-layout-grid-align:none;text-autospace:none"><span style="color: rgb(16, 73, 188); "> </span></p><p class="MsoNormal" style="margin-bottom:0in;margin-bottom:.0001pt;mso-pagination:
none;mso-layout-grid-align:none;text-autospace:none"><span style="color: rgb(16, 73, 188); ">Minimmum batter (lean)
of wall suggested for <3' wall in well-draining soil: 25%<o:p></o:p></span></p><p class="MsoNormal" style="margin-bottom:0in;margin-bottom:.0001pt;mso-pagination:
none;mso-layout-grid-align:none;text-autospace:none"><span style="color: rgb(16, 73, 188); "> </span></p>
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