MATH HELP: Culvert pipe capacity in gpm | Page 4 | Construction and DIY projects | Forums

earthenstead said
I've been wrestling with the notion of drainage for water that infiltrates the fill within the retaining walls. Hopefully with 80% clay soil, not much will enter, but if it does, I'm concerned about it expanding the clay and increasing pressure (I will want to build strong), and about water becoming trapped at the bottom by the concrete slab.

 

I viewed several digrams of draining water from fill behind a retaining wall. They all used gravity and piped it out the lower portion of the wall. Some had a slope they could drain to, and the rest drained to a sump well with a pump.

 

Those won't work for this, especially not with water outside both retaining walls. I'd be letting water in rather than draining it.

 

So then I had the idea, what if I laid the slab over gravel bedding and the slab had lots of drain holes for the water to escape to the gravel bedding below? The only problem I can think of is that with clay soil under the gravel bedding, that over time the soil will break down and become increasingly resistant to seepage over time. (The very process that happens to the bottom of a mature clay bottom pond that helps it retain water better due to a lessening of losses to seepage.)

 

I figured I could approach it one of two ways. Pour the slab and drill the holes once dry, or get something like bamboo tubes (biodegradable) and pour the concrete around them. Drilling risks hitting or exposing rebar/remesh, and with bamboo tubes sticking out, I don't know how to finish the surface with them in the way. (The bamboo tubes could be cut down and centers drilled once dry.)

 

Thoughts?

yeah, I've been thinking about the drainage issue with your clay, I don't know about using block for this, I think it will just cause headaches for you down the road and will be a constant cause for concern, looking through some of the links you posted, I think the cheapest and best option would be to use stone

up here we can get 18 yards of basketball sized stone delivered for about 200 bucks, when you go bigger it's cheaper, but then you need a operator to move them

I think a stone wall with a decent back slope with textile fabric and good fill is the way to go

earthenstead said

KVR said
yeah, I've been thinking about the drainage issue with your clay, I don't know about using block for this, I think it will just cause headaches for you down the road and will be a constant cause for concern

 

Could you explain further about the sorts of problems that you think block would create? Scenarios, links to something that explains and/or illustrates? Specifics?

 

I ask, because I'm in the dark here. I was thinking block could be a good option and am not thinking of any problems beyond those I've already listed.

 

KVR said
up here we can get 18 yards of basketball sized stone delivered for about 200 bucks

 

200 delivered?? As in it covers the cost of the stone and the delivery? What kind and what shape^{(You just answered this.)} of stone?

 

Here, most of the quarries do not deliver. The one which does wants too much money for delivery. One quarry helped with referral to some (dump) trucking companies. The best of those quoted delivery from any of the quarries to my property for $125 per truckload. That does not include material cost.

Just seen way to many examples of block retaining walls that have failed over the years, 

repairs are pretty difficult with them as well, but it all comes down to how you build it and the look you're going for.

Yes, the 200 includes delivery and material