Improving Onsite Drainage

The use of pervious concrete has become an attractive way to improve drainage in the same areas that used to prevent it.

Pervious concrete is an innovative building material with many environmental, economic, and structural advantages. The proper utilization of pervious concrete is a recognized Best Management Practice by the U.S. Environmental Protection Agency (EPA) for providing first-flush pollution control and stormwater management. Property owners and developers can also reduce fees and enhance the bottom line by using pervious concrete, which commonly provides 20-40 years of service with little or no maintenance.

This Is How

Pervious concrete is a mixture of cement, water, and coarse aggregate, and little to no sand. It also frequently contains chemical admixtures. Pervious concrete creates a very porous medium that allows water to drain to the underlying soils. It is commonly produced to allow as much as five gal/ft²/min to pass through the body of the concrete. By allowing rain events to penetrate the pavement to the underlying soils, the first flush of the paved surface is contained on site. The natural infiltration of the area remains unchanged so the water can recharge the water table. This avoids surface runoff that must be held in detention ponds or added to the storm water surface runoff, which must then be treated before it is returned to the local streams.

In many cases the pavement may also be designed with a layer of coarse granular material below the pavement to increase the storage potential of the system. This has proven to be an effective tool to increase the area of usable pavement on a project as well as satisfy local water management regulations.