retaining wall questions, part 2

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bgaviator

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So I have a question about doing the main retaining walls along our back hill, that steeply drops off below our deck. We are having some pretty bad erosion issues, and the other day I was walking down the hill, and my foot fell through a sinkhole! We need to do something to address our issues, but I am completely floored by how much we were quoted from one landscaping company to do this project.

Wall & footing
$26,000.00- $28,000.00
Backfill of walls with mulch top dressing
$2,800.00- $3,500.00
Drainage above steps
$1,200.00- $1,700.00
Concrete steps to lower yard
3,200- $4,000.00
....
There is absolutely no way I can afford this for freaking walls and dirt! This quote was for a two tier system, with concrete steps leading down the one side. My wife and I decided we can do without the steps for now, which would save the $4,000......but the $26-28k for just the two walls floors me. I am wondering if we could get away with just one wall, down the middle of our hill. I think it would stop the biggest erosion concerns, and it would also give me a flat area in which to work on my roof/gutters below my deck. Currently there is no flat area, and it's just a steep hill. I am just looking for alternatives as I can't afford damn near $40,000 just for retaining walls!

We have had a second company come out and they still have yet to get back with us on quotes. I'm hoping they can come in cheaper, or give us some alternative ideas. She stated our erosion was some of the worst she's seen. The one thing that the second landscaper said is that they construct their walls using a concrete base, rather than compacted gravel. All of the info I've read always talks about using a gravel base, so I'm curious if doing it in concrete like they say they do is ok, or if their method is flawed.

Here are some pictures of my hill. The pictures don't do it justice on how steep it is, or the erosion. Some of the trees in this picture are being held upright with straps that's connected to a metal pole that holds a birdhouse.

hill 1.jpg

hill 2.jpg
 
This is where I'd like a wall.....just did this quickly in MS paint.

hill 1 alt.jpg

hill 2 alt.jpg
 
Hire a Geological Engineer to write a spec for the wall. Then you will have a guide post for the contractors to bid by and you won't be looking at apples and oranges. It will be money well spent.
 
so you are saying there is a real possibility my house will slide down my hill?
 
so you are saying there is a real possibility my house will slide down my hill?

We have no clue the integrity of the soil conditions. We are suggesting consulting an engineer to formulate a game plan for the construction of the retaining wall you are considering.
 
Did you ask Landscaper #1 why his price was so high? He/she should be able to break it down for you.
Sinkholes can be formed from buried debris and tree stumps during construction. It takes a number of years for the stumps to rot and then they leave hollow spaces. Hopefully that's the reason in your case. They can be filled fairly easily.
If you have concrete base for a retaining wall, it would have to be fairly deep to serve any purpose. Do you live in an area where where winters are cold, 'cuz then you have to consider frost heaving under the concrete.
 
Unless you can prove the stability of the house I wouldn't do it. I might go more, maybe twenty ft in the dry season and put in an engineered wall. The closer to the house the more the engineering is required. Non of which would be designed by a landscaper unless they come with a set of plans with an engineers stamp on it .
There are lots of choices from stacked large stone, 2 ton lego blocks and and full concrete retaining wall.
http://www.th.gov.bc.ca/publications/Circulars/All/T_Circ/2010/t01-10.pdf
http://www.eaglewestprecast.com/red...FCVMUlmIKKUuBRIvRrLgGrCTNPpQglNkU4aAkst8P8HAQ
http://lockblock.com/products.php
[ame]https://www.youtube.com/watch?v=eTGAGz_gSbU[/ame]
 
no, it does not get real cold here. I am in planting zone 7. we rarely even see snow.

Did you ask Landscaper #1 why his price was so high? He/she should be able to break it down for you.
Sinkholes can be formed from buried debris and tree stumps during construction. It takes a number of years for the stumps to rot and then they leave hollow spaces. Hopefully that's the reason in your case. They can be filled fairly easily.
If you have concrete base for a retaining wall, it would have to be fairly deep to serve any purpose. Do you live in an area where where winters are cold, 'cuz then you have to consider frost heaving under the concrete.
 
How high of a wall do you need?

Here's my story on wall building. I have a walk-out basement and so I have hills to deal with. altho mine are much steeper than what your's appears to be. In order to stabilize the north hill, I began a couple year project of wall building using mortarless stack stones. These stones have a ledger on the back of them that grabs onto the stone below, making the wall "lean" into the high side of the hill. I preferred this type of stacker, as a wall should never be totally vertical--it needs to lean backward.

Anyway, I have 3 courses of walls down this hillside. I dug out and leveled out the dirt after the walls were built and last year I planted them off in creeping juniper. The first wall has gone thru 3 winters now and I live in zone 5 with lots of snow, freezing, etc. and the wall is perfect. These stack stones allow water to escape and is one of the big reasons why this wall is better than a concrete wall that traps water causing it to freeze and the wall to fail.

I did not have to use any drainage in building these walls as it's the toughest, most unforgiving clay you ever saw and the hill dries out fast because the water has a tough time penetrating it. But you might need to add some drainage along YOUR wall. Something to research. There's MUCH written on how to build walls with these stackers. Be sure to put down a good layer of pea gravel into the excavation for the base stone to sit on. Depending on wall height, get one or two courses below grade. And you can't have the wall much over 4 ft. without some engineering consultation. But if the proposed wall is only 3 ft. high or less, then these stones would be a good choice.

It took me 3 years to complete this task--so don't think it's too big for you to handle. I did all the digging alone, but got help handling the stones because it's very tiresome working on a hillside.

After the walls were built, I hired a contractor to put in concrete steps going up these hills. It really looks nice. Rome wasn't built in a day--no problem with taking a couple years to do things in stages as finances allow.
 
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LOL--in looking over your pics again, I see you have used these stacking stones so you already know about them!! I think they are your best bet.
 
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