AAA Home Drainage

French drains, “the past meets the future”. Hand excavated french drains start with an old world aquaduct clean of all debris and dirt. So it is with french drains. French drains are timeless. French drains just keep serving our drainage needs century after century. French drains have been around a very long time in the history of man during both ancient and modern civilization. French drains have been around even longer in their basic form, as simple aquaducts. Throughout time, as early man was inhabiting the earth, french drains were used to bring water to the camp from springs high in the hills overlooking the camp. French drains were used to protect the tent city from floods. French drains were used to run bathwater and toilet use products from the camp in the form of sewage removal.

After all, that is primarily what french drains are: aquaducts.

French drains begin in modern terms as an aquaduct that is hand excavated, as in the old days. French drains now contain an overflow perforated pipe to the allow the groundwater to flow at a more efficient pace when groundwater caused by rain is in greater supply.

We now use river rock, as probably the later versions of old world refined french drain technology did. The story goes that french drains were really created in name by a guy named French, and in America no less. They existed in form long before they were given a modern name however. Most likely, even in ancient times, french drains varied in form due to construction methods and available materials in the area.

In this day of modern machinery, some try to excavate french drains with a ditch witch or backhoe. Nothing replaces the functional ability of the hand excavated french drain groundwater removal system. Straight sides, a flat hard bottom, and clean round river rock is the ticket for great results.

As they say, “accept no slipshod method”. Make sure that the grade of your french drain is 2″ per 10 lineal feet or greater for best results. Insure that your french drain is free of all loose material. Start from the vent; eigther a daylighted vent or a drywell, and hand excavate up through the grade as it becomes more shallow. There is an optical illusion that exists when attempting to see such a precise grade if the viewer looks from the side or above the grade looking down hill. Look up hill within the french drain excavation.

Collect the water on the surface approximately 8″-18″ deep and you will reduce the weight of the soil which is caused by saturation, and subsequently reduce the hydrostatic pressure.

Break up the length of the french drain into lengths of approximately 50 feet lineal for best results. Determine the amount of estimated water that is to be collected and engineer your drywells with that in mind. A daylighted vent has no capacity, but you still need to insure that the water will not desparage a below grade neighbor or some other area where the water will not be wanted.

If you don’t stop adding weight to the top layers of the soil, you will most likely have below grade water problems. If the water is coming into the below grade areas far below that level, you may require an industrial type of excavation and venting beyond the scope of the average residential french drain solution. That scenario is very rare however, and in other articles in this drainage blog I discuss footing drains and underground springs that must be treated differently.

At times the water entering below grade can indeed be referred to as the result of a spring, but the spring is most commonly fed seasonally by the groundwater caused by rains as it is deposited on the surface. These springs usually out during the dry summer season.

If you need a test for which type of spring yours actually is, ask yourself this simple question. Do I see the spring running all year long, even when it has not been raining for sometime? If you can answer yes to that question, you may indeed need to go after the source of the water at a deeper grade. Again, this is not the norm or the most common cause of below grade water problems from my experience.

Below grade sources of water can also be the evidence of failed rain drain discharges laid flat on the outside of the foundation footing or just broken as well. This is especially true of old homes with clay and concrete tiles butted together from early times. Even old cast iron pipe have roots growing through them at times cracking the pipes. Check rain drain discharges by running a hose in the rain drain next to the home where your gutter goes in. Does the water problem pick up in flow in your basement or crawlspace when you test this way?

Rainwater in nature most commonly feeds springs. As rains continue in strength the springs run harder and harder. Cut off the flow on the top layers of the earth with french drains and you will, in most cases, reduce or abate the below grade water problem that you think is a spring. That is my experience.

This entry was posted on Friday, November 2nd, 2007 at 2:25 am and is filed under drainage history, drainage Tips, drainage Info, Misc. You can follow any responses to this entry through the RSS 2.0 feed. Responses are currently closed, but you can trackback from your own site.