Question
I am currently looking into purchasing a house with a drainage problem in the backyard, and was wondering if you would be able to help answer some questions. The property has some water logged spots near the back left corner of the house and also in the middle of the yard. The entire yard pitches from the back left corner of the property to the right side of the property with a slight pitch towards the house as well. There is a low spot near the back left corner (explaining the problem there) but the rest of the property follows the slope described above. The property line to the left is about 2 feet higher and then has a hard slope at their edge onto the property. Towards the front of the backyard it is about 2 to 3 feet above and is almost even height at the back left corner. The house foundation sits about 2 - 3 feet below the house to the left (not the best design) but there are no drainage problems in the basement. However because of this I don't really have the option of sloping the property down from the foundation to the back yard.

My biggest concern, is right now it is the middle of winter and has been about 20 degrees outside for the past 2 weeks therefore I assume the water should be frozen. Yet when I walk out into the yard, the water logged spots are not frozen but still wet and mushy. This concerns me that the water is not from run off or drainage from other properties but from some other source. What are my options for trying to fix the drainage problem?

I was thinking of placing a berm on the left side of the property with pine trees (mostly for privacy) to help the runoff from the property next to me and then placing a drainage pipe system in that man-made channel. Is that something that could help? Also what types of drainage systems are available to handle an entire backyard (probably about .25 acres)?  I was also thinking of regrading the property to slope towards the back of the property and to the right and place more drainage systems along the property line and connect to storm water run off. Do you happen to know approximately how much that should cost as well?

Thank you so much for spending the time to read this long post.

Answer
Brian:
Thanks for your interest in All Experts. This is a good question to ask before you buy this property.

For starters unless this house is just too good to pass up for other reasons like a great price well below market, I would consider looking at another. There are so many houses on the market these days, it does not make sense to take much of a chance when there are so many affordable options.

Second, if it really has been hovering below freezing for the better part of two weeks, then you are right it should be frozen solid...unless it is moving from a warmer location like under ground. And moving water from below ground where it is not cold enough to freeze could mean a spring or seep. It could be seasonal or year round. The only other options are a leaking sprinkler system or water pipe. Or run-off from up slope. However, if it really has been 20 degrees then run-off or snow melt should not be happening. Look for signs that the plant life or soil in the area is different than the other areas. This would indicate a long term issue possibly a seep or spring. Ask about it with the owner if possible. Also walk above the slope to try and identify any overland drainage routes or moving water.
You could also probe the soil with a soil probe and see how soft the area really is. This will tell you how serious the issue really is. If its soft to a depth of 3 or 4 feet in large areas you have a lot of water and a real problem. If its just a small area and only 12-18" deep it may be minor. (Rent from local tool rental)

As for fixing a drainage problem you have only two viable options: 1) Grade the land away from the low spots by changing the slope or adding a ditch or swale. Or 2) install a system of French drains. You may need only one line or several in a pattern connecting to a trunk line if you have several low spots that are not in the same area.

Search my previous answers for French Drains for details on how to do this. It is simple but takes a lot of labor and time. A gentleman in my own neighborhood installed a set of about 6 French Drains running parallel to each other 6 feet apart across his entire back yard with all of them tied to a trunk line draining to a ditch. It flowed year round as he had a spring or seep in his back yard.

And yes if you suspect runoff from above any berm or drainage system to divert the water could potentially help. Although I am not certain based on what you have said that this is run off as it should not be moving in 20 degree weather. Also if you divert the natural drainage you could be flirting with local laws. You can't trap water in your neighbors yard legally.

Your idea of regrading could also be beneficial if it diverts water away from the foundation. As to cost, its very hard to say. Access to your yard, local labor availability, slopes, permit requirements all play into the price. To regrade your yard would also require tilling up the yard, killing all your sod and then re-sodding it. This would likely be several thousands of dollars just for the grass. I have seen many small French drain systems done for 1.5-5K. Larger ones from 5-10K. Add a drain to new yard, grading, etc and I am sure you are going to be at least 5-7K and maybe a lot more.

There are many brands and manufacturers of French Drain systems. You just add more pipes and lateral lines if you have a larger area. Then tie them all to a trunk line that drains to a storm drain if possible. Be very careful that you do not dump all the water from your yard into one point that goes into a neighbors yard. This is illegal. You can not make a situation better for yourself and worse for your neighbor.

Best of Luck
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Sean J Murphy, LA, LEED AP, ISA