Promised Land State Park Bridge & Dam

A deteriorated three-span bridge over a lake and a deteriorating concrete dam provided the only access to Lower Lake’s 220+ campgrounds, 26 miles of hiking trails, and boat launch. An innovative, context-sensitive, and collaborative approach needed to be developed from the beginning. When the bridge is replaced, do we replace the dam? Can portions of the dam and spillway be salvaged? How do we maintain traffic to highly-utilized, recreational resources during construction operations? How do we maintain water levels in the 250-acre lake during construction for recreation use within the Park? What’s the most economically-feasible and environmentally-sensitive solution?

LDG’s approach to this project included collaborating with all stakeholders early in the project process, setting the stage for a successful project. It was determined that the project would be constructed in three phases, so as to maintain traffic and water levels in the lake during construction operations. The most economically-feasible solution was realized by reducing the proposed bridge to a single span and rehabilitating the existing spillway and weir. Environmentally, the project did not disturb any additional area beyond what was disturbed during the original construction of the dam and bridge. The project’s approach preserved the environmental, scenic, aesthetic, and natural resource values of the area, while also improving the public’s safety and mobility within the park and the condition and hydraulic performance of the structure. The project is in harmony with the aesthetics of Promised Land State Park.

Promised Land State Park is located in the heart of the Delaware State Forest in Pike County, PA. The park offers 3,000 acres of land for fishing, hiking, camping, horseback riding, and ice skating. In addition to over 220 campsites, Promised Land State Park has two lakes which contain various forms of aquatic life.

In 2006, it became apparent that the bridge and dam over Lower Lake in the park needed to be replaced. Originally built in 1958, the structures were deteriorating. The Pennsylvania Department of Conservation and Natural Resources called upon Larson Design Group (LDG) to design the replacement of the three-span bridge located over a concrete dam and the lake. The challenge was to maintain public access to the state park’s 220 campsites and maintain water levels in the 250-acre lake throughout the design and construction of the new bridge.

The most economically-feasible solution was to reduce the proposed bridge to a single span and rehabilitate the existing spillway and weir. Environmentally, the project did not disturb any additional area beyond what was disturbed during the original construction of the dam and bridge in 1958.

Environmental impacts were significantly reduced by not draining the lake. Had it been drained, aquatic ecosystems within the lake as well as dependent non-aquatic species outside of it would have been affected. Despite the challenges surrounding the project, construction costs came in $445,000 under budget. Renovations were completed in August of 2012.

On April 15, 2013, the Susquehanna Chapter of the Association for Bridge Construction and Design (ABCD) honored LDG as the winner of the Medium Span Bridge category at ABCD’s annual awards ceremony.

Schnabel Engineering acted as the dam engineering subconsultant to LDG on this project.