By Tim Carter
Enquirer contributor

"It was very effective," Amberley Village resident Billie Schwartz brags about his 8-month-old French drain system, which stops storm water from rushing into his driveway and garage during hard rains.

A linear French drain system | ZOOM |

During extended periods of heavy rain, like what occurred last weekend, basements, garages and other rooms are flooded in houses throughout the Tristate. Some of that water hits the ground and moves the wrong way - toward a home. Other water moves down through the soil until it reaches the region's dense clay. Once there, it begins to travel sideways through the soil until it exits as a spring or squirts through the cracks in a basement wall.

Last summer, Schwartz asked for help with a storm water problem in his yard. Water cascading down a next-door neighbor's driveway and property flooded Schwartz's garage regularly.

In part, the problem was caused by the builder of Schwartz's home. His house, as well as thousands I see on a regular basis, was built too far into the ground. The slope of the driveway apron that abuts his garage was negligible. Leaves, twigs and grass clippings would routinely clog the small drain in the center of the apron. Once the water started to back up, it entered the garage before it started to flow down the drive to the street.

Another common problem that contributes to basement flooding is soil that tilts the wrong way. Look at your soil: Is it level or are some parts near the foundation sloped toward your home? If so, this needs to be corrected before the next heavy downpour.

Some landscapers cause basement flooding by creating raised planting beds near a home's foundations. The mulched areas often create an area where water pools against a foundation.

Follow building codes and you can go a long way toward preventing flooding in and near your home. Most codes mandate that the ground around your home must fall 6 inches within the first 10 feet of horizontal distance away from your foundation. More fall is better. If you can produce 8 or even 10 inches of fall, do so. Before you break out the shovel and wheelbarrow, call your local building department and ask for guidance.

Gutter and downspout drainage is also critical for preventing water inside a home. Last weekend, some areas of the Tristate received nearly 5 inches of rain. When this amount of rain falls on an average-size ranch house roof, such as Schwartz's, it produces an astonishing 7,000 gallons of water, enough to nearly fill an 18-wheeled tanker truck.

The gutters on a home must be clean so this water does not overflow and fall against the house.

Furthermore, the downspout drain lines must discharge into an approved storm water drain system or onto the ground, as far away as possible from the foundation.

Too often I see downspouts terminating on small splash blocks next to the house. This is a mistake - the water simply saturates the soil next to your home.

Some methods don't work

Many waterproofing methods deal with water after it has entered your home. Some companies install drain lines under the basement floor where the floor touches the foundation walls, attempt to channel water into interior gutters that direct the water to a floor drain, install sump pumps, or inject the soil with a slurry that helps to seal cracks in foundation walls.

Many of these waterproofing methods are almost useless.

But I have found that a vast majority of home flooding problems can be permanently stopped by installing a linear French drain in addition to grading the soil around your house and making sure your gutters and downspouts carry the roof water far away from your foundation.

A linear French drain is simply a gutter and downspout system buried in the ground near your home. Its job is to collect and divert storm water that is racing through and on top of the soil.

For years I have used a trenching machine to dig a 6-inch-wide-by-18-to-24-inch-deep trench about 6 to 8 feet away from house foundations. (Locate all underground utilities before you start to dig.)

The bottom of the trench can stay parallel with the surface of the ground around your home. But once the trench passes the edge of the house on its way to the lowest part of your lot, you begin to dig the bottom of the trench nearly level.

I prefer to install a 1-inch layer of large rounded 1-inch-diameter gravel in the bottom of the trench. A 4-inch-diameter perforated drain pipe is then installed on top of this gravel. If you use rigid pipe with two or three rows of prepunched holes, place the holes in the down position. Keep in mind that the water falls to the bottom of the gravel and enters the holes as it begins to rise within the trench.

Once the pipe is in place, fill the trench with the same 1-inch-diameter gravel to within 1 inch of the surface. To catch water traveling on the surface, extend the gravel to the top of the surrounding grass. A strip of sod can be placed over the gravel to hide the drainage device.

If your lot has 18 to 24 inches of fall - and most do - the end of the pipe eventually will expose itself as the trench gets more shallow.

How well do French drains work? Schwartz says, "Water was shooting out the end of the pipe 1 foot into the street. I was amazed at the volume of water the linear French drain was collecting."