Retaining walls

Howdy! Thanks for the pointer over here, @RHinCT . I’m still struggling to navigate this place.

Here’s the story. My neighborhood is hilly and built around what used to be a creek bed. The creek has been routed to underground pipes for at least 80 years, but the water still flows as it would like to flow. The much-increased rainfall in our area in the last couple of decades has affected the neighborhood overall and our yard specifically.

The neighborhood projects are massive, with the county looking to do several years worth of work to improve street drainage. This will (hopefully) prevent the four-foot-deep water that overtook parts of the neighborhood a year ago. Our house is above the low-lying areas and is unlikely to flood like that. But – we are on the slope, neither at highest nor lowest point.

It’s about a ten foot rise up to the house behind ours, about a five foot drop down on one side, and about a 15 foot drop down to the street. There are old retaining walls on those three sides. (The fourth side is level with our property.). The back and side retaining walls are failing – the back is bulging and clearly ready to collapse in the next few months. Perhaps worse, the side wall is sinking, leading the patio to sink and it’s starting to affect the slab that the family room sits on. No bueno.

So okay, I’m all in on keeping the back yard neighbors’ house out of our yard, and I don’t want our house to crack nor to slide onto the next-door neighbor. (She’s elderly and it would scare her cat.)

So far we have an initial estimate for the design and work. I’m really good at picking expensive materials, but even so it’s painful. $125k for just the hardscape stuff so far, and they need to redo the estimate to include pulling up all the patio pavers and relaying those, because we need drainage next to the house and to replace the gravel/sand/whatever it is under there that has washed away and is allowing water to come over the foundation during the heaviest rains.

I will say that this is not the first time I’ve done drainage work in the yard. When the neighbors behind us remodeled, we started getting a lot more water in the yard. When we had 13 inches of rain in 2 days back 15 years ago or so, I was wading in ankle-deep water in three places. There’s a rock waterway that now serves as the major drainage for that part of the yard. That doesn’t need to be redone and is still taking a lot of the water flow. Just not all of it anymore.

In the back yard, it’ll actually be two retaining walls and, unlike all the current walls, there will be formal drainage and water capture behind all of them. My goal is to build something that will last 50 years or so. DH thinks we should think shorter-term since he thinks we won’t live here more than another 5 years. Probably true… but then again he’s talking to the only person in the neighborhood who replaced the slate roof with more real slate so that it won’t have to be done for another 75 years.

Thought y’all might like to hear about it. I’ll come back and give updates as we go along. It’s supposed to take a long time so don’t hold your breath!

ThyPeace, walls.

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$125K sounds about an order of magnitude too expensive, if i’m reading it properly, certainly just for your property.

If you’ve done this kind of work before, you’re familiar with what I’m going to say. There are cement, colored-to-taste interlocking blocks available through any home retailer or landscaping “depot”-type stores. They’re built to offset a few inches back per layer of wall, and they’re cheap for what they are.

With a few feet per wall of those blocks, a few cubic yards of p-stone and a rented Bobcat, you could construct a runoff channel system through/around descending cement block retaining walls. Those walls would each have 12-24" of p-stone behind them, soil over top. If the water coming down the hill around your house was really insane, perforated pipe underneath the pstone with a 4"/foot downgrade to the end of each wall, multiple walls if appropriate.

I literally built a system like this myself 21 years ago in a weekend in my mid 30s.

The paver patio may need some TLC / revision after said wall system is in place around/between/whatever. I also was lucky enough to have the builders of my house rubber-coat the foundation when it was laid, based on experience, so I didn’t have to worry about extensive drainage around the house below the road / fall line.

FC

Well see, that’s the thing. There is literally no way to get a Bobcat onto my property. Everything (EVERYTHING) has to be carried in by hand. And 21 years ago I was also in my mid-30s. Even then, I wasn’t up to the extent of the construction that is required here. Do I think this is expensive? Yes. And I trust this company to give a fair price that is aligned with prices in this area; they work with a couple of the builders I’ve worked with in the past. And yes. Prices here stink.

ThyPeace, in my home town, it would be one tenth as expensive. That’s not where I live now.

I lived on a property like your’s in the 1990s and another with a 13 foot tall retaining wall for 18 years. I know this what you want to here – but before you begin this project get a evaluation by a civil engineer - preferably one with a PE license in civil engineering. I am almost certain there will be codes that say essentially you can not alter the natural flow of water/drainage on adjoining properties. About the last thing people building a retaining wall want is being forced to remove the wall and return the land to its pre-wall condition. Additionally any retaining wall over some single digit height, has to meet certain codes or else FDA insure loans are not possible. (we had a buying higher an engineer to inspect a property for sale - it turned out our wall was 6 inches under the magic height)

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I don’t know anything about retaining walls, but as an aside remember one thing this new place supports is posting images such as diagrams and photos. Sometimes that helps when explaining things.

I had an image of such a machine in my head, but had a devil of a time finding it with Google. At least for moving the material something like this might be able to go where a Bobcat can not.

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Hi @ThyPeace,

If you can’t use heavier equipment like a track-steer, the cost will go up a lot even using powered carts. Digging and demo will require a lot more labor.

For our 3 retaining walls, we had lots of room. We had 3 T770 Bobcats (one parked in the photo) running plus a mini-excavator trenching the foundations. Ended up using 360 tons of 18 inch stone blocks.

Actually, the 20th was the 1 year anniversary of taking the first scoop of earth to begin excavation for the house.

Gene
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Ooo, pictures! How nifty. I’m going to have to post some, then. The property will not allow even powered carts. There is no driveway, and there are 10 steps up from the street to the main part of the yard. There are also retaining walls down there, so they can’t drive over the part that doesn’t have the steps.

Now let’s see if I can post a picture of the latest draft plan…

ThyPeace, learning technology again.

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A post was merged into an existing topic: Posts removed for incivility & personal information or other reasons

You’ve seen photos of my recent landscaping/retaining wall project. Although we were dealing with what I think are much steeper grades, the scope of the project and it’s potential impact on our house itself seems to me puny by comparison with what you’re describing. Our costs came close to $40k so your dollar amount doesn’t look too eye-openingly large to me.

In balancing the 5 year fix vs doing the job right, I’d go with the latter. Even if you do end up moving in the time frame, if our experience is anything to go by, the cheaper options with these sorts of projects rarely age well or even look good from the beginning. The cost savings might come back to haunt you when you come to sell.

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Okay, trying again. Hopefully this is an anonymized version!

ThyPeace, no reason to make it that easy to find me… people might send me chocolate or something. :grin::grin:

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In the picture it looks to me like the green area is level with the sidewalk?
And it looks like that’s at least 8’ wide.

So that’d be lots of room to drive in a bobcat or a mini excavator. (You only need ~3’ width)

That doesn’t jive with your description though - so maybe that isn’t the sidewalk on the left side of the 2D drawing and is something else?

Is the left side of the 2D drawing the street side of the property?

Your text I think says the street side has a 15’ tall retaining wall - that’s a big retaining wall - If you have enough space in front of the wall, building a ramp to go up is a possibility. (to go 15’ high, it’d be a massive ramp. Maybe not worth spending time to construct and remove the ramp if labor is cheap enough there)

Not knowing all of the details, but can the contractor use a crane to get the materials and equipment where they need to be?

It might sound like an expensive option at first, but when you think of the time and energy saved, it may be a good option.

I’m thinking how many tree companies use cranes to remove large trees from property where it is difficult to get close to. I’ve used tree companies in the past that have brought in large cranes, and it’s kind of expensive, but may be a suitable option for you.

'38Packard

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I agree. They’re actually not too terribly expensive for small / quick jobs like this. I’ve had to deal with HVAC units on a roof that needed to be craned out/in and I would guess a mini-excavator is fairly similar in weight. (maybe 2x - not going to be 10x)

The left side is a walkway on the side of the house, not the street sidewalk. It is no more than 3 feet wide, there are steps at one end, and there’s no way to get a bobcat from the street to there without building a ramp that would, as 38Packard mentioned, would be pretty interesting.

As for a crane, that’s what they used 10 or so years ago when the tree came down in the yard. It was about $10k then; I assume it would be double that now. And they would probably need it at least twice. Worth asking about.

ThyPeace, technology is awesome when it works.

There is a mini bobcat people here call a dingo. One of these took a 3000 lb. stone through a “4 foot gate” – that is nominal fence speak. Actual opening less than 48 inches. Landscape people laid 4 by 8 sheets of plywood on the grass.

Here is a picture of the rock and another “4 foot” gate. The rock is roughly 3.5 feet by 6 feet by 14 inches.

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ThyPeace, the original unredacted picture is still attached to that post, at least in the History view…can you edit / delete it?

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Yes, delete the post to get rid of it. It then takes a day for it to disappear. Didn’t want to draw attention to it, so I flagged the post in hopes for a quicker resolution. Thanks for helping out!

(Edit: MF has been kind enough to quickly delete the post.)

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Ooo Criminy, thanks for pointing that out. I deleted the post. And to those who now have my name and address, you really don’t need to send chocolate.

Here’s the text that was with that post, just to try to keep the information in the thread somewhere.

Okay! Let’s see if this will work. This is a picture of the most recently-done plan. There are still details to figure out, particularly on the plan west side of the drawing where it’s all in pencil. We have to figure out the intersection there carefully since that’s close to the property boundary and my neighbor’s house is only about ten feet on the other side of the line. For scale, the rectangles int he lower part of the 2-d drawing are rough outlines of my house. (It’s actually inaccurate, but that gives a sense of the size.) The house is a 3-bedroom Colonial, so quite small. The whole yard is only 0.18 acres.

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