Cutting in a Retaining Wall Footer

[Bunker Buster]

I have a retaining wall I need to put in now that the rains have quit and the ground is drying out. It'll be about 160' from end to end, curved around one side of the house with steps near the middle. The wall will range in height from 1' to 3.5'. The house is built up on a pad and there is a fairly steep slope along the back where a terrace used to be and partially down one side. The ground is washing out under the grass and I need to get the back yard level to improve the drainage.

I have an L2501DT with a box blade, a straight blade and the FEL that I can use. The straight blade has all kinds of adjustments on rotation. I'm looking for suggestions on which tool would be best for the job, or are both needed equally? I'm not new to dirt work, but I'm still pretty green.

Renting a mini excavator is not in the budget (I've priced them). The other option is to have the builder that built the house come out and cut the footer in with a skid steer at $90/hour. The downside is I don't like farming out work that I am physically able or capable to do. The upside, he'd have it done in half the time. haha

 

[D2Cat]

I'd suggest hiring the builder with the skid steer. He knows the area, sees the problem (and will probably do a good job, knowing he should have done something different initially.) and has experience with his machine to do the job effectively.

When installing a retainer wall it's critical to get a good foundation and support going back into the material causing the movement.

You don't get it right, and a few years down the road it will be pulling apart, collapsing, and requiring a start over.

You can focus on saving money now, then have another problem down the road. Spend the time and money now and get it done do it will last!

 

[Bunker Buster]

I've been leaning toward just letting him do it. I agree, it needs to be done right the first time so I don't have to jack with it a few years from now.

 

[niteshiftfromkc]

If you don't want to get the mini-ex, then I would suggest the builder route. I bought my BX25D for the wall I put in. Total wall was about 150' with a 4' to 7' height, not to mention the stairs. I had to dig down two feet as I have 6"-8" of compacted AB3 for my base and had to bury 12-16" of the wall. Due to the height of the wall and the city codes, I needed to have mine engineered.

What type of block are you putting in? After a lot of research I went with the Keystone as the pin technology seemed to be the best for my situation. I would definitely check with the block manufacturer to see how deep to bury them as well as what type of footing. Also, don't skimp on the drain tile behind it with plenty of gravel.

I started by renting a BX instead of the bobcat/mini-ex combination. As luck would have it, I ended up purchasing a new BX since the project was taking longer than I expected.

 

[Bunker Buster]

The builder came out to discuss the project and we came to an agreement on a reasonable price. Having them do it will ensure a solid and level foundation. I'll spread crushed concrete for the base and then the wall will be built with quickrete bags, tied together with rebar.

There are a couple other places across the front that will need a much smaller retaining wall which I'll tackle myself.

 

[cerlawson]

A civil engineer here for what it is worth. I assume this is a gravity wall, not a cantilevered thing. Gravity walls usually have to be a least 1/3 the wall height for the thickness, front to back dimension of the wall. You probably make that OK.

Chances are you have very little frost depth, but if you do start at that depth.

On the backside for most walls there is the need to keep soil from washing through seams and joints to the front during heavy rains. A filter fabric usually is needed there, but if you fill the zone right behind the wall and for a foot (front to back) or so thickness using a mix of sand and gravel as one would for making concrete (2 parts sand 4 parts gravel), that also is a filter for any soil.

The landscape fabrics are probably OK for the filter.

 

[Bunker Buster]

Correct, we don't have much of a frost depth here. I'll be starting out roughly 12" down.

I'll be putting a gravel / sand base down as well as the back fill as you suggested.