5 Common Landscape Drainage Problems.
1. Uncontrolled runoff
When water flows it will always seek the lowest spot. In most cases, when it comes to landscaping, water will flow towards the edge. This causes a problem because the edge of a landscaped area is usually dirt. When the water volume increases, the dirt will erode. It will eventually leave the landscaped area, where it will wash off into the gutter then into a nearby catch basin. The problem is, the homeowner will eventually lose more dirt than expected and a large empty patch in the yard will have to be filled.
Solution: The first step in fixing this situation is to know the drainage pattern of your yard. Check if it flows to the left, right, or lower part of your yard. Once you see the drainage pattern, it’s best to reinforce that edge with medium size pebbles to protect the soil from eroding or leaving the landscaped area. This creates a rock lined swale; a very useful technique to protect erosion, commonly used in most drainage projects. Even though this is a smaller version, it will make a huge difference.
2. Low point/ Sump areas
Low points in most yards can be created when a house is built or by a contractor who doesn’t have a specialty in drainage. Low points are the lowest area a water can go in any given yard. Sometimes, even with additional water added, the water is considered stuck. This is called a sump. Sumps are difficult to fix, especially when the hardscape of concrete has been built around it. It is still possible to fix these low points, but the contractor has to be very skilled and creative to make this happen.
Solution: A commonly used structure to fix a low point is a French drain. A French drain is a perforated pipe that is built underground with special technique to collect water from surrounding dirt. This special technique ensures that the French drain will last for years and will guarantee that the perforated pipe will be free from dirt and rocks during a heavy rainstorm. For this system to work properly, there should also be catch basins located at certain locations. These catch basins are used to clean out the pipes and make sure there isn't anything causing the pipe to clog, like debris or even roots from surrounding trees. A good drainage contractor can layout the pipes quickly and efficiently.
3. Improper Inlet Location
Whether the project is large or small, inlet locations seem to be a puzzle for most contractors. It’s very common to see drainage inlets located at high points or even an area where the inlet isn’t picking up any water. Also, it’s common that there aren’t enough inlets or the inlets aren’t big enough for a particular area. As a result, you end up with areas flooding quite quickly during a rainstorm, but when the rain stops, you see the water slowly drain into the pipe. If the rainstorm went on longer than expected, the flooded area could damage the footing of the home or seep into the house and cause damage.
Solution: For any drainage problem, you always want to study the lay of the land around the home. Find out which area can collect water and visualize how much water can possibly flow at that location. If the water is coming from the roof, you would expect a lot of water. If the water is coming from a narrow walkway, that would be a lot less. If there is an area that you know will flood a lot, it would be a good idea to either put a larger inlet or install two inlets.
4. Improper storm drain pipe location
When laying out storm drain pipes, the average person may not know where to put them. Some argue the pipe has to be on the high side of the yard, so that it has good cover, while others may say the opposite. When the pipes are located in the wrong place, the expected water runoff will not enter the pipe. Instead of the water entering the pipe and discharging out to the street, the water will sheet flow somewhere else, bypassing the pipe completely. This is very common.
Solution: The first step for any storm drain project is to always look at how the water flows in your landscaped area; know where the ridges and low points are. It's best to get a feel for how steep the grades are. That is most likely the limit of the slope of a pipe you may consider building at that location. Once you get a picture of how drainage flows in your yard, the next step is to sketch out your yard and draw the high and low points. From there, you will be able to picture the best location for your storm drain pipes and it will be easier to keep track of your layout. This will also help you avoid the other problems mentioned in this article.
5. Drainage surfaces flowing towards the home.
This is more common than you would expect; there are 2 scenarios. First, a dirt area that is against the house foundation. Second, a concrete area that is against the house foundation. There are a few solutions for when dirt is adjacent to the foundation, but there are only a few for when concrete is adjacent to the foundation.
Solutions: For the scenario with dirt, you can fill the dirt next to the foundation and regrade it, so the surface flows away from the home. As a result, you will have a swale a few feet from the foundation. The only problem is, the dirt can erode depending on the steepness of the slope. If there is a good amount of water, the swale could end up flooding and eventually end up back into the foundation. A more involved solution would be to construct a French drain along the foundation of the home. As long as you can fit at least one 3” storm drain pipe with a half percent slope, it will be a very good improvement. The French drain has to drain out to a curb or into an existing storm drain pipe.
For the scenario with concrete against the foundation, you have the option of breaking the concrete and having it rebuilt so that the slope is corrected. Another option is to break into the concrete against the home and add storm drain pipes with inlets to catch the water. Unfortunately, these options are time consuming and will have a higher cost compared to the previous scenario. It is best to find a good drainage consultant who can help you to find the best solution for your home.
