U.S. Department of Interior,
National Park Services
C&O Canal Little Falls Creek Spillway/Culvert Rehabilitation


Construction Management
Traffic Management
Soil and Erosion Control
Stream Restoration


This project involved the rehabilitation of the spillway, retaining walls and floodwater protection system for the culvert that diverts Little Falls creek underneath the C&O Canal and active WASA sewer main. Work involved earthworks, the construction of gabion mattresses and baskets, rehabilitation of the concrete retaining walls, backfilling, restoration and re-vegetation.

The project was complicated by the sewer line which is a main sewer transfer line for the District of Columbia. The line was constructed of cast iron which prevented the use of heavy equipment within its vicinity. The line was also pressurized and could not be shut off or diverted. Any damage to the line would result in a significant and damaging sewage spill in a sensitive ecological environment. All work had to be completed by hand and small equipment. The restrictions on the site required the use of a 25 Ton crane to transfer gabion materials and concrete form the main road to the work area.

A component of the project involved the construction of a concrete retaining wall within Little Falls Creek. This presented a challenge for two reasons. First, the weather had to be monitored closely because the creek is a major tributary and a storm would quickly flood the work area and destroy the concrete form work. Second a portion of the concrete had to be poured under water. Global was able to complete this work in the first attempt in accordance with the specifications.

Access for the site was located off of the Clara Barton Parkway. All equipment and materials had to be delivered using this main arterial road which is converted to one way during rush hour. This required careful planning including a traffic management plan and traffic control procedures. A temporary entrance way and temporary traffic signs were installed. Deliveries of materials and equipment were restricted to outside peak travel times. When the project was complete all construction signage was removed and temporary entrance ways were restored and re-vegetated.

© Global Consulting, Inc. 2006