Mechanical Remediation Dredging in the Lower Harbor

Solicitation Number: W912WJ-17-R-0003 Restrictions: Unrestricted Title: Mechanical Dredging in the Lower Harbor, New Bedford Harbor Superfund Site, New Bedford, Massachusetts Location: Lower Harbor of New Bedford and Fairhaven, Massachusetts * Please note that the Presolicitation Notice was posted under W912WJ-16-R-0002 and the new Solicitation number is W912WJ-17-R-0003. The U.S. Army Corps of Engineers is issuing a Request for proposal for a new Firm-Fixed-Price construction dredging contract utilizing a best Value Tradeoff acquisition approach. The project involves the mechanical remediation dredging of PCB contaminated sediments and disposal into a Confined Aquatic Disposal (CAD) Cell. Work consists of providing materials, equipment and labor for mechanical dredging of approximately 138,000 cubic yards (CY) of material and depositing it in the Lower Harbor Confined Aquatic Disposal Cell (LHCC). The work requires the contractor to achieve precise dredge cuts. Dredging, placement of material into scows, transport of the material, and depositing of material into the LHCC must be performed with minimal spillage or turbidity. All work to be performed under this contract including all dredge areas and the LHCC is located between the Route 195 and Route 6 bridges. The scope involves dredging in depths of up to 30 feet of water and as shallow as 3 feet. Sediments placed into the LHCC will be dredged using mechanical dredging equipment with an environmental bucket (closed bucket). Debris removal and disposal will be required prior to dredging and may include discarded metal objects, timber, and abandoned piers. Dredging accuracy will be key to minimizing the amount of over-depth dredging while still attaining the required dredge elevation. State-of-the-art monitoring and positioning systems are required to ensure dredge accuracy requirements are met. The debris removal and dredging shall be performed so that the project-specific turbidity criterion of 50 neptholometric turbidity units (ntu) above background measured 300 feet down-current of the dredge area is not exceeded. The dredged sediments will be placed into split-hull scows for transport to the LHCC. Free-standing water collected in the scows/hoppers shall be decanted and filtered using activated carbon to ensure compliance with this same 50 ntu turbidity criterion. A silt curtain and oil boom shall be placed around the perimeter of the LHCC.