Proper Drainage Essential When Designing A Landscape

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  • Post last modified:September 3, 2012
  • Reading time:5 mins read

So you want to landscape your home, your castle, your best investment?

Well, let’s take a look at where you might start and how you would go about the art of landscaping while avoiding the pitfalls of inexperience.

Most self-help books and even lectures by Professionals in any field will begin with the basics trying to guide the beginner toward success and away from failure. Focusing on the frosting before you bake the cake is an altogether common approach by beginners often resulting in dead plants or worse.

Too much moisture wicking from the concrete slab into the house, mold and even the structural failures of walls, columns and banks are a common occurrence. This is why drainage and proper irrigation install are probably first on the list of importance when creating your personal dreamscape.

Drainage is key and should be designed to remove any and all surface water. Downspouts should tie into the drainage and be adequate in size to accommodate the run-off of an oversized impermeable roof. Most people stop here with the drainage; in reality, this is only the beginning. To serve many years, drains should not be flexible, permeated with holes or open in any way to the invasion of tree roots.

SDR35 is a good quality drainpipe that is semi-rigid and glues together easily with Red Hot Blue glue. It carries water away from the house without saturating the soils near the structure. Drain boxes that daylight to the surface must have plastic built-in mini-reservoirs that catch sediment and soils at the bottom of the drain box as the water circulates from the surface into the drainpipe system. This prevents the buildup of sediments in the drainpipe and allows for easy cleaning from the surface.

Where does the water go? Typically, in older homes, the run-off goes into the gutter and then the storm drain system along with engine oil, gas, brake dust and fertilizer. Now, cities are requiring that run-off be treated through a series of natural applications on site that slow it down, and return much of the moisture back to the earth.

For example, new construction in Encinitas requires that a seepage pit be placed on the property to collect rain run-off from the roof and surrounding landscape and allow it to re-enter the soils below grade. Technically, no water is supposed to leave the property. This is facilitated by digging a 5-foot-by-5-foot-by-5-foot pit, lining it with filter fabric and filling it with one to two inches of gravel. The drainpipe from the yard enters the pit vertically and forms a T at the bottom with perforations along the sides of the pipe to allow for percolation. Perforations on the vertical stand pipe also help distribute the water into the gravel as the pit eventually fills with water during heavy rain.

This system has great merit but it has been my experience that when the 100-year rain makes an appearance, like it has for the past few years, the gravel perk pit cannot accommodate all the run-off and problems begin. Most lots built in the last few decades are graded so that they all drain naturally to the street.

The back of the lot is usually higher than the front, depending on the location, and water will naturally course along the sides of the home (if graded properly) and eventually make its way to the street where the storm drains are located.

In most cases placing the drainage pit near the front or in a low spot and away from the house is probably the best location for it. If the rain is continuous and fills the pit, the water will begin to back up the drainage pipe preventing the surface drains from working. Having an escape for the drainage into your yard at a low spot away from the house is a very good idea at this point. If it rains long enough, the surface of the soils becomes saturated and any further moisture will take a while to be absorbed eventually becoming run-off.

Protecting your home is the landscaper’s first job. Design, beauty and functionality must work together to accomplish this primary goal.