On or about April 27, 2010, approximately 15 feet of the southern portion of the Culvert collapsed outside of the Roadway. In April 2011, DDOT hired an Engineering firm to determine the cause of the failure and design the repairs of the culvert. The emergency inspection showed the roadway approaches to this culvert remain structurally sound, with the caveat of shifting the traffic away from the southern portion.

This “overtopping” was caused by a number of consecutive days of high rain events and snow melt from the winter. On August 5th, DDOT met with the consultant regarding their findings and recommendations. During this process, the Consultant provided the Flood Profile from FEMA. This profile shows the 10-year, 50-year, 100-year, and 500-year storm events overtopping the roadway.

Because of the serious risk to public safety posed by this collapse, DDOT might have to close Kalmia Road, NW prior to heavy rain events or prolong rain events such as a Hurricane until repairs can be made.

Since August 5th, the Consultant preformed additional Hydraulics Analysis. The additional analysis will aid DDOT in identifying the options that will be available to repair the culvert and will also identify the various environmental regulations and requirements that will need to be met.

The design approach was based on the following:

• To prevent water from flowing over the roadway during heavy rainfall, the new culvert will have a larger opening that is 20’ x 9’ to allow for more water to flow underneath it. In addition, the opening will allows for debris to pass through and not block the opening of the culvert.
• Repairing the last 20’ feet of the 60” storm sewer.
• The narrower width of pavement helps DDOT meet its goal for impervious service removal. Per the new Municipal Separate Storm Sewer System (MS-4) Permit from U.S. Environmental Protection Agency (EPA,) DDOT is required to convert 1,500,000 square feet into non-impervious surface. With this project, we are converting approximately 900 Square feet from Asphalt to grass and tree line area.
• The culvert opening will be constructed to allow Aquatic Organism Passage (fish and other aquatic organism).
• The constructed culvert will aesthetically match the other culverts within Rock Creek Park.
• In addition to the replacement of the culvert a 12” waterline that was installed in early part of 1940 will also be replaced.