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More About Swales: With Great Benefit Comes Great Responsibility

Are swales and culverts used often for drainage? 

Yes they are! Swales are often dug along property lines to direct water to street drains. Most people aren’t aware that there is even a drain there. They don’t take any particular notice of the depression in the soil and think nothing of it, when all of the water between the houses is directed to the storm drain instead of leaving pools on their property.

Take a look at this illustration of a swale and then the photograph of 10 properties that are swaled to a single culvert! What a wonderful solution to getting water off the properties… Maybe!

What if some of the 10 property owners leave trash in their swale depression, which is washed down to the culvert anytime it rains? Is anyone in the community going to be responsible for seeing that there is no trash building up on the grid during rainfall? Trash or debris building up on the culvert grid can become a very effective plug. A pond can be formed very quickly, behind the culvert opening, in heavy rainfall, which can in turn raise the water table on the surrounding land. Hopefully the drainage designer has allowed for such a possibility and has designed the residential lots, so that a rising water table will not flood the basements of the surrounding homes or cause the sump pumps to be operating continuously.

Swales are marvelous, but they do require maintenance and supervision. You can’t allow a swale on your property to build up with debris to a point where it causes water to flow onto the neighbor’s property or perhaps in the direction of your own basement. It is simply illegal to allow water to flow off your property on to your neighbors land and I’m sure you don’t want to wake up one morning with a wet basement yourself!

We would appreciate hearing from you, if you have an opinion or a question on swales. In fact, we would like to hear from you anytime you have a comment or an idea to share on any of these blogs. Communication is a two-way street, so let us hear what is going through your mind.

Doug Hastings
MN Home Inspector, Minneapolis & St. Paul
Kaplan University, Home Inspection Lead Instructor

Rob ‘Pops’ Leslie
Kaplan Professionals, Retired

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That’s Just Swale: Water Drainage Help for Homes on Hills

What is the purpose of a drainage swale and when do we use it?

MN realtors and homeowners, you have been waiting patiently for the description of a drainage swale. So here it is! A drainage swale is a depression in the ground designed to direct water flow. You may have found one accidentally on a country road where a depression has been made to drain water from one side of the road to the other.  Sometimes, in order to avoid this dip or depression in the road surface, a pipe is placed underneath the road so water can more easily flow through it.  This underground pipe and manhole is called a culvert.

Swales are very effective at directing water flow away from the house. Imagine if your house was on a sloping lot with the house being part way up the slope and the water flowing down the hill toward the house. A swale could be installed, by creating a perpendicular depression, at a point above the house to deflect flowing water around the house. Then, it is directed into a culvert or a second swale taking all the water from the hill to the street drain. Swales may also be bermed on the lower side to direct flow and carry more water.

Berm… swale, culvert, berm… what strange words! The swale is a strategic depression in the ground that directs water flow and a berm is a man-made rise in the ground that achieves the same thing. An example of a berm would be levees that are used to contain flooding rivers.

Previously, I stated that we could use a swale in places where we could not create 6 inches of fall, in the grade, in the first 10 feet sloping away from the foundation of the house. Imagine if the boundary line of your house was within 5 feet of the foundation and there was only 2 inches in slope to the boundary; you would not be able to achieve the code required 6 inches ground slope in the first 10 feet of fall. This could be achieved by digging a 4 inch deep swale perpendicular to the foundation, with 2% fall to the road drain. Water would flow freely to the road and away from the home foundation.

What is the purpose of the swale?  Home inspectors know and now you do too!

Doug Hastings
MN Home Inspector, Minneapolis & St. Paul
Kaplan University, Home Inspection Lead Instructor

Rob ‘Pops’ Leslie
Kaplan Professionals, Retired

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