Removal of Bloomsbury Dam

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 to 3 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 municipal property approximately 1,000 feet upstream of the dam. The contractor will remove a majority of the dam 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, root wads, etc., will be performed along the river banks for approximately 250 linear feet along both sides of the dam, as well 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.

Division 02 -	Existing Conditions, Subsurface Investigation.
Division 31 -	Earthwork, Site Clearing, Grading, Excavation and Fill, Subgrade Preparation, Excavation, Shoring, Tunneling and Mining, Tunnel Excavation.
Division 35 -	Waterway and Marine Construction, Dam Construction and Equipment.