Removal of the Bloomsbury Dam on the Musconetcong River, New Jersey

Removal of the Bloomsbury Dam on the Musconetcong River, New Jersey The U.S. Army Corps of Engineers Philadelphia District is seeking contractors for the Removal of the Bloomsbury Dam Project. The place of performance is the Musconetcong River located between the Borough of Bloomsbury (Hunterdon County) and Greenwich Township (Warren County), New Jersey.

The work to be completed consists of two major components: The breaching and removal of the Bloomsbury Dam down to the original river substrate and disposal of the demolition debris. The stabilization of the river banks and channel bottom adjacent to the dam and additional bank stabilization measures along the former impoundment upstream of the dam.

RELEVANT INFORMATION: The dam is approximately 7 feet high, 40 feet wide, and 170 feet long. The exterior of the structure is reinforced concrete. The interior is assumed to contain concrete, stone, and possibly the remnant of a former timber crib dam. Approximately 15,000-20,000 cubic yards of sediment is impounded behind the dam and is proposed for passive release to the downstream through a phased removal approach. No dredging of sediment or diversion of the river is proposed for construction.

Removal is estimated to occur in 2 phases and will require flexible timelines due to the uncertainty of river flows and sediment movement. Construction will require monitoring and adaptive management for sediment movement, turbidity, and archaeological resources. Pre-construction may require aquatic mussel presence/absence surveys and relocation of mussels.

GENERAL DESCRIPTION OF WORK: The contractor will install and maintain construction access drives and staging areas in two locations. The first is on a former industrial facility directly adjacent to the dam, and the second is on a residential property (Block 30, Lot 7) approximately 1,000 feet upstream of the dam. The contractor will remove a majority of the dam and a portion of the existing retaining wall down to the original river substrate and dispose of the demolition debris.

Sections of the dam (approximately 10 feet in length) will be left intact near the river banks and stabilized with rock to maintain the integrity of the existing abutments. Additional stabilization with rock, geotextile, embedded root wads with duckbill anchoring, etc., will be performed along the river banks for approximately 250 linear feet along both sides of the dam, as well stabilization using an imbricated wall consisting of stacked quarry stone, rock and geotextile at select upstream properties.

In-stream stabilization structures will also be constructed, which may include boulder clusters for fish habitat creation. The former mill race on the north side of the river will be filled and stabilized as riparian habitat. All disturbed areas will be stabilized with temporary and/or permanent native vegetative cover.

SPECIALIZED EXPERIENCE: Contractor must demonstrate past performance and success in completion of at least 5 dam removal projects with at least one in the past 5 years, that are similar to this project in size, scope, and dollar value. Contractor must demonstrate expertise in construction projects occurring in a dynamic riverine environment. Contractor must demonstrate experience with a construction schedule and scheduling software. Contractor must demonstrate successful past performance evaluations. Contractor must demonstrate a satisfactory safety record.

PERIOD OF PERFORMANCE: The contract will have an estimated 365 calendar day completion requirement. The contract is anticipated to include phases of construction which will require flexibility due to uncertain river flows and sediment movement. Regulatory environmental windows may impact the period of performance. The contract is expected to be awarded in September 2024. The estimated cost of construction is between $3,000,000, and $6,000,000.