Parking Lot Drainage Swale

They are a key part of the city s stormwater drainage system.

Parking lot drainage swale. Deicing salts can damage soil structure by reducing soils organic matter. Stormwater drainage design is an integral component in the design of parking lots. In several case studies done in portland oregon savings ranged from 4 000 to 5 500 per acre of developed area. Section 1 4 2 green parking lot facilities cross section materials used in the various green parking lot facilities shall be in accordance with the green streets specifications appendix k 2 6.

Stormwater drainage design for parking lots ace group llc course outline parking lots can be seen almost everywhere from shopping centers to office buildings to schools. Swales are used to capture sheet flow from a parking lot or trail surface and in most places where a ditch is traditionally used. Swales are the broad shallow channels along roads driveways and parking lots that are designed to keep water off your road. Swales collect that rushing water and helps to control that water drainage by directing it to catch basins drain boxes and curb drains.

Parking lot islands curbless in a paved area with no curb pre cast car stops or a ribbon curb can be installed along the pavement perimeter to protect the swale area. Green parking lot facilities shall be designed per the green street standard drawings appendix k 2 4. This course covers the basics of designing an adequate storm drainage system for a parking lot. The minimum slope for grassy swales and drainage ways is 1 percent to prevent standing water and muddy conditions.

This application of swale should only be attempted where shallow grades allow for sheet flow conditions over level entrance areas. Slopes greater than 5 percent may make the construction of special ramps for the disabled necessary. One of the three swale types described below are recommended as trailside drainage in place of a simple ditch for linear stormwater controls as needed adjacent to the trail. The maximum cross slope is 2 percent.

Maintenance responsibility is normally that of the owner. Slopes for walkways will not exceed 5 percent unless unavoidable. Additions of mulch added organic matter may be required if drainage to swale is from roadway or parking lot.