View Full Version : soil amount above rock

02-06-2011, 12:05 AM
hi guys, have a question, i have this place that has 3/4 crushed rock and some drain rock 2 to 4 inch in size, this is all held up with retainer blocks.from the house to the top of the retainer wall, is about a two foot elevation difference, about 30 feet away. instead of removing the rock i was thinking one could build the retainer wall up and cover the rock with soil and sod. how thick should one go with the soil so the sod will grow good? or

02-06-2011, 03:08 PM
or would this work??????

02-06-2011, 03:24 PM
Hard to picture in my mind, what you are doing... My first question is, why would you plug up a drainage system with dirt?? Sounds like some effort went into that particular system, and was designed to drain away lots of water...

Patriot Services
02-06-2011, 03:38 PM
I agree with smallaxe. That slope might not look like much, but I bet you would have an erosion and washout issue. Not to mention if you raise the wall height you might need an engineers report.

02-06-2011, 03:55 PM
it is a little difficult to explain, i will try and get some pics this week, i dont believe its for drainage, if its not how much soil over that would work, if one was to cover it or would it work? its about a 1,200 sq, ft. area. well any way i know its not for drainage. its more like a hard scape that they had put in years ago.

02-06-2011, 05:56 PM
I would personally water in a lot of washed sand and put 3-4" of loam over that, for sod. for a planter, I would remove enough rock to have at least 6" planting depth...

02-06-2011, 06:05 PM
If i were me i would remove some of the gravel and put down some kind of land scape fabric to keep the dirt from washing down in to the gravel add another block to add as much dirt as you can. I would like to see 12 inchs of dirt.

Just as long as the yard slopes away from the house.

The more dirt you have the better grass will do because that part of the yard will dry out faster the gravel will let the water settle out of the dirt faster.

02-06-2011, 07:47 PM
wait i have a pic, thanks for the inputs. this will give a better look on what i was trying to say'

Patriot Services
02-06-2011, 08:07 PM
Well its not high enough to be of structural concern. However you probably need to remove about a foot of that rock. Even then it looks too shady to grow really nice grass. Those evergreen monsters need to go too.
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02-07-2011, 01:36 AM
Depending on how the water comes off the house, I would start just with grass up to the log and see if I could get it to grow there, then expand over the stones.
It looks like the far end, from the picture's perspective is quite a drop in terrain. Is this entire yard on a hillside?
I would not take any responsibilty for wht might happen once this drain is filled in. I would give a disclaimer to the owner that it is not a good idea, but I try to make things work for the client's wishes... :)

Patriot Services
02-07-2011, 09:06 AM
It just doesn't look like a turf friendly area. How long have they lived there? Somebody took a lot of time. Its not attractive but I think it is purposeful.
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02-07-2011, 12:35 PM
It just doesn't look like a turf friendly area. How long have they lived there? Somebody took a lot of time. Its not attractive but I think it is purposeful.
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There are a lot of ways to dress up that area that are much simpler and inexpensive.

One could easily go with various pots or other ornamental hardware. A trellis standing up behind the wall and showy from the house with a vine that fits the area.
That is what I'd probably do and I'm sure you could get more ideas from people that have a sense of decorum and taste... :)

Think Green
02-07-2011, 02:32 PM
It wouldn't matter if you took out two feet of rock and replaced it with soil and geotextile fabric, it will become dry and kill any type of grass you put on there.
During our droughts, turf that is over underground drains will become depleted of moisture and the turf dies. In our case, of bermuda grass, it withers but returns with rains. Other than that, with fescues, etc. it will not recover as quickly.