Have you ever looked out at your yard during a rainstorm and been shocked to find a rushing rapid where there was once a peaceful lawn? This is called streaming water, and it can occur in hilly yards or anywhere areas of higher elevation converge at lower elevations, collecting water and creating a downward-flowing stream. Streaming water can cause erosion and make growing grass and maintaining landscaping a hassle. Installing a French drain can greatly reduce the adverse effects of streaming water.
However, it’s not advised to undertake any construction projects in your yard before referencing local building codes and regulations. Just call 811, and you’ll be directed to your local utility companies for a free utilities marking in your yard.
After that, the first step to installing a streaming water French drain is to determine if one drain box or culvert will be sufficient to handle the volume of water, or if additional ones are needed to collect all the water. Next, locate a proper area to which the water can be diverted. Make sure this is an area lower in elevation than the beginning of the stream and is properly suited to serve as a water receptacle. To ensure that you’re not doing anything illegal or harmful to your yard, read up on proper places to divert water.
Once you’ve located the beginning and end points of your drain and determined the necessary amount of drain boxes or culverts, you should then:
- Scoop out a trench 8–12 inches deep that has a constant downward pitch. If the trench doesn’t maintain a continuous downward angle, then the water flow will be working against gravity. It’s recommended that you rent a trench digger, especially for longer drains, as this step can be laborious
- Pour a 2–3 inch layer of gravel into the trench. Make sure the gravel is at least ½ inch to 1 inch in size with no smaller rocks. Smaller rocks will find their way into the drainpipe’s perforations.
- Place a perforated or perforated with a sock drainpipe in the ditch on top of the gravel.
- Fill in the rest of the trench with the same coarse gravel, surrounding the pipe on all sides with at least 2–3 inches. Cover the gravel with 3–4 inches of topsoil.
- Install a culvert or drain box compatible with 4-inch pipe at the beginning or higher end of the pipe, and at the lower end where the water will be diverted, install a 4-inch end cap or pop-up emitter. This gives the water a place to enter and exit the belowground stream.
Result: When it rains, the water streaming from higher elevation in your yard is safely contained in a drainpipe. This eliminates the “wash-out” effect, preventing erosion and promoting a healthy lawn.