French Drains

A big problem for parking lots can be subsurface water problems that continually cause asphalt to fail in specific areas. This underground water can come from a spring, a lot of clay in the sub-base, or even landscape islands that absorb water and allow water to filter under the pavement.

For this reason, French drains can be a significant part of many of our patching and resurfacing projects. We can relieve this underground water pressure by digging a trench or trough 18” – 24” deep. We install filter cloth and an open graded crushed stone in this trench line. The open graded stone allows a place for water to collect and where the underground hydraulic pressure can be released. The trench is dug between this collection point and the release point. The release point can be a nearby catch basin inlet or a drainage ravine, etc.. A 4” perforated plastic pipe is also placed in the lower center of the trench. The entire trench is filled with crushed stone and wrapped on top with filter fabric. The end is either opened to daylight in the case of a ravine, or tied directly into the catch basin approximately 18” – 24” below the pavement surface. As water is squeezed into the trench, it can absorb into the compacted open graded stone, into the pipe and travel along its length to be released into the catch basin or ravine. The filter cloth surrounding this system keeps mud, silt, etc. from getting into the stone and compromising its porosity.

French drains are very effective for situations where constant water problems are an issue.

CHAMBERLAIN CONTRACTORS, INC.
162 Lafayette Avenue, Laurel MD 20707
1-866-670-1234