WASHINGTON NATIONAL CATHEDRAL
STORMWATER MANAGEMENT AND RAVINE RESTORATION
Washington, District of Columbia
With the construction of the Washington National Cathedral and its environs, the amount of runoff generated from the site was greatly increased from pre-development conditions. This increase in runoff, which for any size storm was instantly piped and concentrated into a ravine in the Olmstead Woods, was the cause of severe erosion and forest degradation. By concentrating the flow in this fashion, the soil mantle was denied the sufficient amount of water to keep the woodlands healthy. Similarly, the runoff from the neighboring St. Albans School area was also directed into a ravine, where its negative effects were also apparent.

To mitigate these problems, a series of infiltration and stream stabilization measures were implemented in the summer of 2002. The volume of runoff from the Cathedral and its environs was greatly reduced by collecting it in gravel filled recharge trenches along the edges of the Cathedral parking lot and Pilgrim Road, as well as a RainstoreTM bed underlying a garden area. Besides reducing the volume of runoff, these measures have also positively contributed to the area's receding water table. Stream stabilization measures, such as check logs, rock check dams, and bioremediation, have also greatly restored the capacity and aesthetics of the two ravines.

Site Photographs

This infiltration trench constructed along the main driveway intercepts stormwater runoff from the parking area and adjacent roadway.

Construction of the RainstoreTM bed at the Cathedral

Installed RainstoreTM infiltration bed at the Cathedral

Eco-engineered checkdam along the eroded ravine.

Newly installed infiltration trench along the grassy contour.