Landscape Drainage | Swales and Drainage Pipes

by Mary Ann
(Colebrook, NH)

A question about landscape drainage and some solutions by way of swales and drainage pipe.

I'm attaching a photo of my son's house. It's a 100+ year-old farm house that he and his wife bought about a year ago. It's obvious in this photo the damage that is being caused by water "pooling" in the L between the house and the garage. Even the bottom of the garage door has rotted off. He'd like to fix the rot, but needs to address the drainage problem first and we don't know where to start. (He tried to dig a trench, but the property sits on ledge.)

ANSWER

Hi Mary Ann,
The water that is collecting in the L must be diverted away from the house. I am assuming that what your son was trying to do was to dig a trench in preparation for installing a french drain. This is a drainage pipe with holes in it. Water is allowed to percolate into the pipe and then the pipe is pitched so that the water is led away to another location.

This is one option. If there is rock there, you can drill it out...a pain in the neck solution, but doable.

Another solution would be to remove the walkway leading to the front door. Re-grade the land so that it pitches away from the garage. This should be at 1/4 inch per foot. I would grade it in that direction and in that way to at least the other side of where the walkway is now..plus a bit. So if that distance turns out to be 8 feet, that area should be 2 inches lower than the garage area. You now create a swale, which is a channel that takes the water away to someplace else. See my page on landscape grading. This channel will run parallel to the house, but get lower and lower so the water can flow away. Usually this is not very noticeable.

While you are grading, you should also grade the land up against the section of the house where the front door is. This should also be graded away from the house.

As an alternative to a swale where the gravel driveway is, you could re-grade as suggested, but place a trench drain in the area where the swale would have been. This is a drain with slats in it. The water would enter this drain and then connect to a solid pipe running under the rest of the swale, leading the water away.

You might consider taking some of my ideas and giving them to a landscape contractor or good excavator. They have the equipment to do all of this. I know that all of this is an expense, but better to get it out of the way and fix structural problems first. I know, because I have a very old home too. It's so much more fun doing the fun stuff, but unfortunately water problems must be dealt with to avoid current or future problems.

The walkway can then be replaced...concrete, pavers, or even stepping stones. These paving materials are some of the less costly options.