Retaining Walls

StoneHeartFarm · Jun 23, 2001

GlueGuy,

Hadn't thought of gasoline. (Of course, I've never tried to store gasoline in a foam container.) /w3tcompact/icons/wink.gif Actually, that's a pretty clever way to make a casting. Hmmm, I gonna have to kick that one a around for awhile. Every now and then I have a need of some small piece of technology like that. Making shapes is probably the single most important skill a human can have, technology wise. If you think about it, everything man builds requires making shapes. If you can't make shapes, you can't build, only repair.

Anyway, the open grid idea for the retaining wall sounds interesting? The same type of thing can be accomplished with precast blocks (I've seen them made from chimney blocks) cemented together, but I don't think you would get quite the same strength out of them that you would get from a poured grid.

SHF

StoneHeartFarm · Jun 23, 2001

Matthew,

What are you going to use to blow the air down into the tubes? I think there are standard blowers available for 6" tubing. Will you be using any solar? A DC blower could probably run off a small solar panel. The advantage is that the blower will only run when there is sun. But, since that's also when your greatest heat gain can be expected, it seems the two would go hand in hand.

Also, have you considered how you will prevent the heat which has been transferred down the tube from simply coming straight back up the tube (chimney effect/thermosiphon) when the temperature falls?

SHF

mlmartin · Jun 24, 2001

I expect that I'll be using two squirrel cage blowers, one at each end of the building. I have 20 amps at 220V available at the building site, so I'll be using that for powering the blowers. I'm going to use two thermostats to control the blowers. One near the ridge to turn them on when there is enough heat to be worthwhile and another either in the rock bed or at bench level to prevent heat collection when it's not required.

Since the risers will be connected to manifolds at the bottom of the storage, there will be little thermosiphoning. The chimney effect should be minimal as long as the greenhouse vents are closed. If it becomes a problem, I'll install counter weighted dampers that will be opened by the air pressure from the blowers.

Matthew

StoneHeartFarm · Jun 24, 2001

Matthew,

Sounds good. Keep us posted. I'd be interested in seeing the rough sketches when you get to it, and of course pictures of the construction! /w3tcompact/icons/wink.gif

SHF

mlmartin · Jun 24, 2001

Thanks for the questions. They forced me to think through some things that I had been putting off. Right now it looks like the greenhouse is going to be a Spring 2002 project.

Matthew

GBear · Jun 24, 2001

Sitting here at my desk, I can see out the window and part of a 400 foot retaining wall made from Allan Block, AB3’s and AB12’s. 65 tons of block and 125 tons of rock. I built it without help and did a lot of it by hand, with a mattock, wheelbarrow, hammer, and chisel. The Kubota and a diamond blade in the Skilsaw helped too.

One of Glueguy’s links was Allan Block, which is what I used. Each block weighs 80#. It is flexible construction and no concrete or steel are required, perfect for the owner/builder. Water drains through the block, but in some parts I ran perforated drain pipe in the gravel behind the wall to daylight.

I actually put the last cap in place last week. I started last September, but I chugged along at a pretty consistent 20 or so hours per week on this huge project. It is some classy looking stuff. It is as artsy as it is functional and I got pretty creative with the several sets of steps, curves, tiers, planters, and turnouts built into it. I knew nothing about masonry or retaining walls when I started. Look at that site; it’s where all my ideas started. You can download all kinds of instruction manuals in PDF format and pictures at both the AB and Keystone sites.

Nothing against boulders, but the block option has a totally different look, can be integrated into the landscaping, and can do a lot more than just hold back the dirt.

GlueGuy · Jun 25, 2001

The poured grid would be the strongest, but without holes to let out the water, it would tend to "tip". If you ever go that way, I would like to see what the plans look like.

We have a couple places where we want to put retaining walls. A couple of them are relatively short, but one is going to be a big job. The big one will probably end up being the alan block; not decided yet on the two short walls...

The GlueGuy

MarkV · Jun 25, 2001

Mlmartin,
Your greenhouse project made me think of a passive solar heat/cooling system I have always wanted to try. I see that you have a backhoe and the system I was thinking of uses a "U" shaped ditch, below frost line, with standard culvert pipe laid in. The idea is to end up with an intake and outlet of the culvert loop into the building. The intake has a small blower to move air through the culvert and the air is conditioned by the constant ground temps. If I remember right the gound temps below frost line mantains at 68 year round. May not be practical for your site, but I bet your thermal engineer friend would have a handle on sizes of pipe and amount of run required. Plus it could be fun to dig that trench./w3tcompact/icons/smile.gif

Another passive solar system using culvert pipe I saw involved capping the ends of several pipes, filling them with water, painting them black and standing them where they would get sun. This provides a large mass, in a relatively small space. Guess the down side would be that it would work just as well in the summer when you didn't want the heat gain./w3tcompact/icons/frown.gif

MarkV

StoneHeartFarm · Jun 25, 2001

<font color=blue> if you ever go that way, I would like to see the plans </font color=blue>

GlueGuy,

Actually, I was kinda hoping you'd have some ideas /w3tcompact/icons/crazy.gif

SHD

StoneHeartFarm · Jun 25, 2001

MarkV,

Ground temp will depend on the location and the time of year. The ground temp is like a fly wheel, warmer in the fall (after summer sunshine) and cooler in the spring (after winter). I thought about the tube heating plan, but, this far north the ground temps don't rise enough to get an acceptable gain. So, the system would need some kind of air to air heat exchanger that would trap the warm air inside the house. Otherwise, heat from the house would be warming the ground since heat likes to move from warm to cold.

What the tubes are good for is cooling. The ground temperature is almost always lower than the air temperature, except for a short period in the spring and another in late fall. Here, we call them "cool tubes" and I have 2 built into my new home. They are made from 6" S&D PVC and tie into the crawl space approximately 11' below grade. From there, they rise diagonally along the main floor rear wall and surface at each rear corner of the house. When finished, they will have "candy cane" tops with screens and screw on caps. The idea is to cool the air in the tubes where it is in ground contact. Cool air falls and that will create a negative pressure at the top, which will draw warm outside air into the tube, to be cooled by the earth contact. If it works, it should "power vent" my crawl space, if it doesn't...well, I needed a couple of extra vents to meet code anyway and there was basically no other place to put them. /w3tcompact/icons/crazy.gif

Somewhere around here I've got a book that charts the annual temperature change and gives the high/low point by month. If you're interested, I can try to dig it out and post the cycle for you.

SHF