Grading question...Newbie, please help

robce05September 8, 2012

I would be very grateful for some advice please. I just moved in and want to install a lawn in my backyard. Currently it is a sandbox (nothing there) so I am going to have to amend the soil quite a bit to help with the clay soil and get the ph right. I figured while I�m doing this I should also get the grade right. I asked a friend of a friend in passing who is a retired architect, and he says you must have a 3% slope on all landscaping to prevent pooling (which I definitely do not want), and at least 10 ft of the slope has to be in the direction directly away from the house. I would have no problem blinding following his advice, but there are obstacles that make following his advice a little difficult. So my first question is; is he correct?

If he is, here are my obstacles. The yard is 56 ft long running from south (the back door of my house) to north (the back fence) and 20 ft wide (east to west). Now the bottom of the east fence is 1.5in higher than the bottom of the west fence, excluding the board that the fence sits on which is 7in below the fence. The east fence does not have a fence board (or whatever you call the board that the fence sits on). The neighbors to the east and north have yards that are level with my property line, the western neighbors yard is slightly lower than mine (hence why I believe they put in the fence board). Now what I originally thought of was to have the 3% slope running from the east to the west, but that would be 7 in which would run the water straight into the fence board, which I am worried would rot out the fence board quicker and also pool the water. But I�m thinking that no matter where I put the slope I am going to have that problem (since the water would hit either a dirt wall or fence board) unless I haul in tons of dirt and slope the water to the eastern neighbor which I really would rather not do. I�m also worried that if I did that I would have to put a lot of dirt on my west fence which will be a pain to deal with when having to replace the fence.

So what would people do if in my shoes? I have attached a picture in case that helps. I am facing North and am standing about in the middle of my yard. Thanks in advance for taking the time to read this and offering your advice.

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There is a lot of good information on line regarding grading around your foundation. Generally you want 10' out from the foundation to be 6" lower than the soil at the foundation. That gives you a 5 percent slope. You can go a little less but the closer to 5% the better you are.

After that 10' it's good to have the ground continue to slope away from the house so that you don't have a swale 10' out.

As far as pooling in the landscape, that's going to depend on your climate and how well water percolates through your soil. Increasing the organic matter by adding compost will help with that as well as improve your soil for planting grass. From the looks of things you don't seem to have any major depressions in your backyard. Are there any areas that you see pooling in currently?

    Bookmark   September 8, 2012 at 10:12AM
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I'll offer a tip that if you describe the situation in such a way that it sounds like a complex, detailed, trick algebra problem, you will lose participants. For a forum, the description should be simple.

There is no way to stop water from coming on to your property. What you need to make sure of is that there is no grading or "devices" added that RETAIN water and keep it from running off of your property. Likewise, you cannot concentrate the water and funnel it toward your lower neighbor's property. If the natural drainage is toward the west, that neighbor cannot install a board that dams the water to keep it from leaving your property. If there is such a board it would be to your advantage for it to rot away. Hopefully, the situation could be worked out in a better way rather than having to rely on the process of decomposition or calling Morgan & Morgan. Your photo does not show this board and how it is retaining the water, so it's not possible for us to evaluate. Please post pictures that show what's stopping water now and where the water should go. (No close-ups, please. It's also the surrounding context that's needed.) Though it helps to have sandy soil for drainage, you cannot rely on it as the only method for dealing with rain water.

    Bookmark   September 8, 2012 at 11:07AM
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rob, we'd like to know where you are, what zone. Care needs to be taken of the existing root system of your trees. Don't know your plan for incorporating the amendments you referenced. You can't till it in within the reach of your tree's root system as you'd be really messing with feeder roots.


    Bookmark   September 8, 2012 at 4:06PM
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Forgot to add. Before you do anything to your soil send a sample to your local cooperative exchange office for a soil test. It will tell you what you need to add to it.

It is pretty odd to not have anything growing not even weeds. I see what looks like a stump in the middle. Were there more trees and shade before? If there was no reason for vegetation not to grow call your extension office and tell them the condition of soil and see if the recommend any specific tests.

As the stumps and roots rot they'll take nitrogen from the soil so you'll need to add extra fertilizer in those areas. I'd recommend using organic fertilizers because you don't have to really worry about over applying most of them and applying too much around the stump areas won't be a problem.

If your soil is as bad as you describe and your soil test shows your soil is low in organic matter (make sure you get that test done) I'd start by adding at least a 1/2" layer of compost over everything and work it down about 4" into your existing soil. 1" would be better and you don't have to worry about smothering any existing lawn so if you don't mind the money/work go for 1"

1/2" would be 1.75 yards of compost for your backyard. 1" would be 3.5 cubic yards.

If you're worried about hurting the tree roots with a rototiller you can use hand cultivators to work the compost in. At least around the trees. You can do the whole thing by hand. I've done a similar size with hand tools and broke it up into a few hours each day for 2 days and stocked up on sports drinks.

The compost will help with a lot of different problems including soil structure, pH, fertility, etc. With that much compost you won't even need to fertilize when you put seed down. But keep something on hand and sprinkle it over the areas where you cut down the trees once a month. You can use one of those hand held spreaders. I'd pick up some Espoma Plant Tone because you can get it in smaller bags than lawn fertilizer.

One final tip. As you work the soil and regrade it you're going to fluff it up and it will settle down once it rains. Contractors that do this work use various tools to get the soil to settle hopefully without over compacting it. Skid steer doesn't seem appropriate for your backyard but maybe a plate compactor? At the very least a lawn roller. Ask someone with more experience than this (maybe your local rental center?) I'm just providing this as a heads up.

Compost isn't a good medium to do the grading with so first take care of that, bring in top soil if needed or a mixture of sand and compost, then add compost where you plan on putting down grass.

    Bookmark   September 8, 2012 at 10:17PM
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