front yard runoff and storm water control

by Linda
(Annapolis, MD, USA)

Hello, I have a question about storm water control. Our house is on top of a fairly steep hill with woods on three sides and a large terraced plant bed in front of the house. When we have heavy rains, the water sheets off our lawn and into the plant bed, creating large deep ruts all the way down the slope and leaving huge piles of mulch/soil on the lawn below.

We are considering installing a swale with rocks at the top of the planting bed at the edge of the lawn in hopes that this would slow down and capture some of the water. Do you think this would help and if so what would be the basic specifications for designing such a swale (i.e., size, depth and materials).

Our home is about 4 yrs old and we have the problems with clay soil that has been compacted in the area that was cleared for the house site, which includes the front slope.

Any guidance or advice you could provide would be greatly appreciated.

ANSWER

Hi Linda,
From what I see in the photo, I don't think a swale will work. I will explain why, but don't worry becasue there are other solutions.

It appears that if you look at your lawn, the elevation is higher towards the driveway, then it gets lower, and then it goes up again. The concept behind a swale is that the swale gets lower and lower until it reaches its exit point. So in your case, this would not work.

One of the problems I see is that the bed adjacent to the lawn area is mostly mulch. There is nothing there to hold it in place. A retaining wall would work, but that is quite an expense. So here is what I would suggest. It's rather simple, but it will work.

You need to plant that bed heavily. It also looks like you have excess mulch, so remove most of it. The idea is that the plants will completely, or almost completely, cover the bed and mulch will not be needed anyway. Too much mulch can be a problem in sloped areas.

It looks like the area is hot and sunny. I would recommend plants that will take dry conditions (xeriscape plants). Some can even spread.

I have a slope in my front yard along the street. I don't know if you have visited my page on Xeriscape Plants, but please do so. It shows my slope and many of the plants I used. These plants will work in Maryland. I have NO runoff problems and my area is steeper than yours!

Briefly, you can use Junipers, Thyme, Sedums (both Autumn Joy and the low ones, Catmint (great perennial) as some suggestions.

This will solve your problem, although you may have to wait a year or two for the plants to provide the coverage needed. And it will be visually attractive too. Plant in masses. Again, removing most of the mulch will help too.