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Bad Soil Drainage

Posted by mudgod none (My Page) on
Wed, Jun 6, 12 at 2:42

I'm having soil drainage issues. I was planting a flower bed near the foundation of my house. I dug a few holes (6-7 holes about 8" deep) and it rained afterwards.
The next day 1 hole was empty/dry as I expected but the rest were still full of water. It took them 2 days to completely drain out.
Rightmost hole drained...others full of water
I held back on planting since I'm worried that I'll just wind up killing the plants.
Is there anything I can do to improve drainage?
Someone told me to dig deeper add a little sand and some humus to improve drainage of the soil. Is that all or what are other things to do?
Incidentally we had really bad rains a year ago and the same side of the house's basement got flooded (not sure if the two are related)


Follow-Up Postings:

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RE: Bad Soil Drainage

I absolutely think the two are related. You can't have water sitting next to your foundation/basement walls. The land should slope away from the house so water runs away ("good drainage.") Flowers are the least of your concerns right now with an issue like this, and the last thing you want to do is allow more water to seep down along your basement walls. That's "bad drainage." That will cause the walls to eventually crack (which may have already happened if you're flooding.) If still left untreated, the walls can begin to cave in. At that point, it's an expensive repair to have steel I-beams installed to hold the walls in place. I've been there, done this.

It doesn't look like you can build up any higher against the house, so investigating how to get a slope away from the house could be tricky.


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RE: Bad Soil Drainage

It would be imposable to diagnose and or advise you as to what to do without knowing the type of soil involved.
What the soil is may have an effect on the foundation of your home.
Typically the building pad should have had a 5% slope away from the house and the bed placed upon it. This usually does not happen as the builders don't pay much attention to code.
The fact that the existing soil does not drain can mean that it is expansive. This type swells when water is added, sealing off passageways for the water to drain. If the soil is dug out or amended in a ditch (bucket effect) with no drain then it can swell and cause uplift of the foundation. Drainage of any excess moisture must be drained away from the bed. Guttering and slope help but the bottom of the bed is were water will stand if not corrected. Some builders used sand under the slab. If to much water enters this sand it can erode out.
Remedies may include trench drains, dry creek beds, area drains or properly installed french drains as a last resort.


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RE: Bad Soil Drainage

What type of soil do you have?
Clay soils hold water really well. The water cannot move easily through the tightly packed soil particles. Amending clay soils with organic matter will, eventually, open that up so the water can move more freely. you would need to add between 45 to 75 percent sand toi that clay to get the same results that about 6 to 8 percent organic matter will give you. This link may be of some help.
However, you may also need to install a drainage system since your basement is getting flooded.

Here is a link that might be useful: Foundation drainage systems


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RE: Bad Soil Drainage

+1 on all the above posts.

We have clay and if it doesn't drain we plant things high - that is, the root ball partially above ground and the soil mounded up around it. But this may be of limited use in your situation.


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RE: Bad Soil Drainage

  • Posted by RpR_ 3-4 (My Page) on
    Wed, Jun 6, 12 at 12:30

How old is the house?
Was it built on added or natural soil?

I would rent a powered post hole digger and drill some holes as deep as possible to see what is actually down there.


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RE: Bad Soil Drainage

I too was wondering whether any foundation drainage was originally installed, and whether the house sits on a slope at all (which would tell you whether the foundation could be drained by gravity or a sump pump).

If you do any boring or digging, make sure you know where your buried utilities are!


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RE: Bad Soil Drainage

House:
It was originally an older house (50's cinderblock foundation) but it was extended 5 years ago and this half was made with a new poured foundation.
I was told at the time of purchase that there were two sump pumps for either side of the basement (old and new). They're under a finished pergo floor. I have been able to locate one (hear it) on the cinderblock side but not the one on the side this bed/poured foundation is. I bought a few years after the construction so I don't the specifics of added vs natural soil (though it was an extension from the 50's where they doubled the foundation).
Also I'm in Northern Virginia and I've been told we have a lot of clay in the area.

Grading:

The bed itself is largely flat (and I'd guess 5 feet or so wide) followed by a 3 feet sidewalk and then a highly graded area. .I'd guess 3-5 feet slope over 30-40 feet. I've also never experienced any significant standing water in the yard.

Flooding:

The flooding happened once in the 18 months I've been here and that was during Tropical storm Lee which caused widespread flooding and deaths in the area. I haven't had any issues before or after so not sure how concerned I should be. The flooding seemed to be coming from the edge where the wall and floor met. The window wells and wall etc were dry.
Also incidently more then half my neighbours also got flooded during that storm.

Short Term Plan of Action:

I've bought a few bags of humus, sand and potting soil. I was planning on digging up big (deep) holes and putting a mixture in to improve drainage. Any recommendations on ratios.
I was also planning on putting some humus over the entire bed and then working it into the top few inches
Anything else I should do for the flower bed themselves

Long Term Plan of Action:

I called in a couple of flood / water damage companies. They proposed digging up around the inside perimeter of the basement and then installing a french drain. Additionally they suggested digging up the flower bed area and waterproofing the wall there (some tar like compound) and then backfilling it. The prices quoted were pretty high (8-20k) due to which I punted especially since it only happened the one time. Also there seemed to be a thin layer of cement on the foundation with a pink board material underneath. It has cracked in a few places where the soil and foundation meet exposing the underlying pink material (it's not insulation but something outside of the foundation and second thin layer of cement).

@RpR_: If I do a deep hole, how deep should it be (as deep as the basement floor? What should I be looking for?

Sorry I'm not quite aware of the right terms , new at all this :D

Thanks for all the help :)


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RE: Bad Soil Drainage

OK, this sounds a lot better. You have quite a slope away from the house there so that's going to protect you for the most part.

Your plan may have some problems though. If you dig a hole in an area that gets saturated and put in a porous medium - like sand - water will come in from the saturated ground and sit in it. They call it the bathtub effect. Problem is it doesn't actually drain any water away from the area.

I'm no expert but I'll throw this out. If you want to drain this area for better plant growth as well as helping out your sumps downstairs, it looks like you could do it yourself with some gravity fed drains. Dig a trench along the length of the house under where you want to plant. Maybe a couple feet deep to get below the root zone. At right angles dig another connecting trench out to the hillside so you have a big T. Lay in a couple inches of sand, put in perforated drain pipe, cover with sand, replace the soil. The end of the T daylights on the hill. cut it off at an angle flush with the ground so you don't hit it with the mower.

I'm sure someone will find a problem with this but that's my 2 cents.

I'm mystified as to why anyone would seal up a sump pump under the floor. There should be access hatches or something so the pumps can be serviced or replaced. What if they break down and water fills the sump and comes up into your floor? Yikes. You should figure that out before you really need to get in there.


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RE: Bad Soil Drainage

The soils I have seen in Virginia do not contain a lot of clay they are clay. Clay is small, pretty even, particles that can fit tightly together and impede the movement of most anything through, so you need something that will seperate those particles to allow the flow of water and that is organic matter.
Humus is organic matter, but what I have seen is the bags of humus usually are more expensive then the bags of compost (pretty much the same stuff). Keep in mind that it probably took several years for your soil to get into that condition and it can take several years to correct that problem unless a drain field is installed. A drain field means you also need to look at where that water will be going.


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RE: Bad Soil Drainage

  • Posted by RpR_ 3-4 (My Page) on
    Sun, Jun 10, 12 at 4:22

Mudgod:

Get a post hole digger that has a blade a foot to sixteen inches in diameter.
Usually they can go down three to four feet depending on if the operators have used one before. (If you actually bend over till the handles are nearly on the ground you gain about a foot or so of depth.

Now do it this way firstly to see how deep the clay goes. (I have found it so deep that one mounted on a skid-steer is necessary to to get below the clay or dig a hole (dry well) that stops the plants on the surface from drowning.

For this you dig the hole as deep as you think will function best, fill the bottom with pea gravel or coarse sand and put planting dirt above that.


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