The retaining wall is finally underway. The initial 20' will be used for cordwood, after that, I just want heavy material around the garage foundation. I have 3/4 stone immediately behind the wall, about a foot. They recommended "sand fill" which has some small stones in it. 1) not so sure that is the best material, it needs tamping I think....water application didnt make it firm enough to walk on alone. 2) it seems to drain well, like sand on the beach, the water just disappeared. I don't have wet ground, no water moving around. The only water will be rain/snow. I liked their "aggretate"3/4 grey stone with stone chips/sand. It packs HARD but they didn't seem to think it would drain well. They also thought sand fill would be a better product than "dirt fill". Am I moving in the right direction, or would a different material be better as a back fill? Edit: around the garage, on one side, the wall will hold driveway parking. The wall will be 10 feet wide. At its deepest, might be to 6". Sca
I'd imagine sand can get washed out through very little cracks and crevice's. We had a small leak in our above ground pool liner that let all the water out, and carried the sand below with it. Made a heck of a mess, transferring it to my lower yard.
Good points. Not sure what to think about keeping it from running out....except a good layer of gravel between wall and sandfill. Far as freezing....ambient ground temp here is 52°. It would have to be pretty cold to freeze the thermal mass of the wall (better than 24" thick in the thin spots) then gravel then sand. From the top, if our frost line is 18", I don’t see that causing too much issue.
More times than not, the guy doing the work uses what he thinks is best as far as local products. Ask him what he'd do if it were his house. Pretty much everything is going to settle a little (over time) and over compacting during backfill can be hard on any wall retaining it.
If you’re nervous about the wall moving with backfill weight against it I’d use stone because it drains, as opposed to anything with clay in it. Sand would be next best when stone is overkill. Gravel is a mixture of different sized aggregate, sand, and/or clay if it’s road gravel. It may drain or may not, depending on what’s in it
Awesome. I haven't figured it out yet, but plan to tamp it as I go. I THINK stone would be overkill...there's zero subteranian water moving around, everything is surface, and that I'll have to work with. ....like topping the whole mess with a good layer of stone. I was considering topsoil and grass, which would grow well there. Not that I want more lawn to mow. But grass and topsoil would absorb....and excess would run off.....where stone would allow water directly into the backfill material. Fun studying all the issues. Part way through today's progress....and my ever present broen eyed girl
Just an amateur here myself. In 2020 I built a small railroad tie retaining wall as preparation for the 16' pool I put up that year. From what I was reading, drainage is important for the long-term integrity of the wall. You don't want to be holding back a mini reservoir. For backfilling I just used the native soil I had in my backyard. What I did before backfilling though was to put a layer of crushed stone down for drainage. To keep the soil from migrating into the stone rendering it worthless, was to cover the stone with drainage fabric. So in theory, surface water passes through the backfill material, through the fabric, then the stone, then eventually makes its way into the sub soil below. So far the system has had zero issues. Oh, I also used crushed stone as a base for my wall too. Maybe that's a moot point, but its what I did. If the fabric idea appeals to you, I have an extra roll of it kicking around you can have.
Can you put drain tile in? The tires might retain more than just wall. Water needs a way to escape as absorption will lead to pushing the wall out. Round self leveling stones don't tamp well at all.
#57 gravel, or stone? Stone wouldn't need compacted, would it? If so then maybe a "jumping Jack" tamper, and good balance?
According to our building department, round pea stone and 3/4 - 1” (maybe other sizes too?) concrete stone is compacted as it dumps out of the truck. Enough so that it was legal for us to dig a trench to below the frost line, fill that trench just below the surface with stone and then pour a footing on top of it and it was considered frost free
I also live on a sand bank, where buildings are. I would put in a drain like Eric Wanderweg describes above BECAUSE if you get a 1/2 inch of rain and you have a dam need to get water out! here we would use crusher run which is 3/4 minus meaning holes in grates everything below 3/4 could fall through or bank run which is usually cheaper just not measured. Both more or less pack under their own weight
Plate compactor or "jumping jack"...just to help jiggle the gravel facets together, not necessarily compact...Although it will lose some height, so it can be considered compaction.
They did exactly that at the house they are building next door. And that is the extent of my "knowledge" on this subject
