Big Slackwater Chesapeake & Ohio Canal National Historical Park
Barry Isett & Associates (BIA) is a member of a team that had the responsibility to plan the restoration of an impassible section of the Chesapeake & Ohio Canal National Historical Park, which follows the route of the old Chesapeake & Ohio Canal and linked Cumberland, MD, to the Georgetown section of Washington, DC. The towpath that runs parallel to the canal was once used to provide footing for the mules that pulled the canal boats but is now enjoyed by bicyclists and hikers along most of the 184-mile trail.
Two major floods in 1996, washed out sections of the towpath and caused the closure of the Big Slackwater section. Hikers and pedestrians were forced to take a five-mile detour along winding and narrow public roads that offered vehicular danger.
In 2007, The National Park Service engaged a team of design professionals to design repairs to the trail. As a consultant to Farewell Mills Gatsch Architects LLC of Princeton, NJ, BIA provided surveys and site design services in the restoration of the towpath. BIA conducted a topographic survey of about 2.5 miles of the towpath, coordinated a side scan sonar survey to provide images of the river floor and riverbed adjacent to the closed towpath and prepared a base plan for future design use, integrating the side scan sonar data, providing contours above and below the water line.
Virginia bank and the Rod man on the Maryland shore. To cover the difficult project area, BIA’s environmental scientists used their own boats to ferry staff across the river. In late August, BIA's overall project manager Bob Cox, PE, PLS, hacked his way through the underbrush along the 1.5 mile reconstruction route along with BIA colleagues to review every cross section, check design grades, verify culvert locations and make an overall check of the preliminary plans. The "on foot" team included project structural engineers Keast & Hood staff members. Preliminary design work had begun in 2007 with a feasibility study prepared by HDR, Inc. and Keast & Hood, Co. BIA provided surveys for that phase of the project as well.
The design consisted of a nine-foot wide gravel trail, stabilized with 14 inches of gravel, geogrid and geotextile. An imbricated riprap system was proposed to help stabilize the edge of the trail at certain locations in close proximity to river banks. Geotechnical investigations identified additional locations, where soil conditions would not allow a stable gravel trail. A jet grouting system was proposed to stabilize these areas, allowing the preferred gravel trail. The final, and most technically complex aspect of the project, involved approximately 0.9 miles of the path which ranged from zero to just a few feet in width. For these areas, elevated precast concrete spans were proposed. The 40-foot long precast concrete spans were designed to rest on concrete piers which would be poured in place. Many piers were constructed directly on bedrock, with some even located in water. BIA was also able to assist with obtaining a stormwater approval from the U.S. Army Corps of Engineers, and erosion control and stormwater management approvals from the Maryland Department of the Environment.
The path opened to the public in October 2012.
- Site design
- Topographic and boundary survey services