French Drains – Solutions to Poor Draining Yards

Anyone can have issues with water accumulating in low spots in your yard. In years where conditions are extraordinarily wet, this can lead to real serious problems and damages from flooding to structures and more expensive landscaping or pools and driveways. if you notice a problem in a give year, you may be well advised to address it before the problem can compound itself. French Drains can be a simple, effective DIY solution to these problems.

Additionally, if you have a sloping lot, the water running across the surface (particularly unsodded surfaces) can cause erosion problems. The solution is to provide a controlled channel (French Drain) for the movement of the water to a retention area for safe and slow absorption back into the ground or draining it along a designated path towards retention beyond your property. You need to be extra careful not to take your runoff and dump it uncontrolled onto you neighbors property as this will only cause you bigger problems.

French Drain Profile

A French Drain is a channel for water to drain away in to a specific spot under controlled conditions. This can be as simple as a trench filled with crushed gravel or stone. But the force of water moving through the crushed stone can cause the fines of the soil to filter into the open spaces around the gravel diminishing the effectiveness of the drain over time. It is better to construct a stage 3 French Drain that will have both a perforated pipe buried in the trench and a fabric to separate the soil fines from the gravel maintaining the effective flow of the water through the drain.

Perforated drains are easy to install and not very expensive. Your largest expense will be the excavation and restoration of the excavated area. If you have had draining water damage the area, this is an expense you were going to incur anyway so it pays to install measure to prevent a recurrence.

First you need to understand how the water flows across the property. If you are not clear about this or it is not easily apparent, do not hesitate to call a professional civil engineer for advice. This may even be a requirement (some jurisdictions require French Drain systems be permitted and be designed by an Engineer). A small investment with an Engineer may save you big headaches later.

Once you determine the slope of the lot and where the water is emanating as a source, you need to determine where you want to direct it to. This could be down to the street, it could be down to a sloping hill that directs the water to safe retainage and in some instances you may even need to install either above ground retainage or underground storage to store the water until it can percolate into the ground naturally or to be pumped to another location.

French Drain Storage Tank

Once you have your plan, determine how big a trench you need – this will depend on the amount of water you want to handle. If you see the gross amount of accumulation that occurred when you had the problem and can guesstimate the width by the length x the depth of the water, it will give you a rough estimate of the amount of water (cubic foot wise) that you have to be able to accommodate. Depending on the planned slope of the trench (suggest a minimum or 1/4″ per foot) you will get an idea of the width, and depth of the French Drain trench and the size and number of perforated pipe you need to put in it. Again, if any of this seems unintuitive to you, call on a Civil Engineer. They may save you from over designing or under designing the system. It is important to verify that the drain is sloping towards your intended direction. Check it with a level as you proceed to dig your trech and as you lay down the stone bed on the bottom of the trench. Verify the slope on the perforated pipe as a final check before laying on the top layer of stone.

The basic components of the system are:

Perforated HDPE Pipe (perforation sizes and patterns vary).
Crushed Stone or Gravel (pit run).
Landscaping Fabric.

Perforated Drain Pipe

Crushed Stone

Landscape Fabric

You may find it easier to rent a light backhoe to dig the trench or possibly a Ditch Witch. Most Importantly, CALL YOUR LOCAL UTILITIES BEFORE YOU DIG – it is the law in most states and it could even save your life. Once you have gathered your materials, laid out the path, located the underground utilites, you are ready to build your French Drain go. Once last bit of advice, wait till the dry season or you will have a royal mess on your hands.