Lombard Dam Removal
Maine Rivers, as part of the larger Alewife Restoration Initiative (ARI), required engineering design and construction support for the removal of the Lombard Dam in the Town of Vassalboro.
Kleinschmidt initiated the project by conducting a due diligence assessment including an evaluation of visible conditions that could impact project design, schedule, or cost. We developed a structural assessment based on an onsite structural and condition inspection of the dam that included observations of the condition of the dam, spillway, gatehouse, and abutments to determine structural deficiencies and corresponding repairs. We conducted a wetland delineation and vernal pool identification to support the permitting efforts. Kleinschmidt created and calibrated an HEC-RAS model of the existing dam and proposed restored condition that was used to evaluate impacts on flooding and material sizing in the restored stream. Kleinschmidt developed a design suitable for inclusion in the permit application and finalized the design following comments by project partners and regulators. The design objective was to provide fish passage for diadromous and resident target species (alewives and American eel) and restore wetlands in the former impoundment, while conforming to standard engineering practices for dam decommissioning, including sequencing of removal, reuse of onsite materials, and natural channel design concepts. The design included the removal of the dam, the design of a restored stream channel in the immediate vicinity of the dam, and a revegetation plan for the current impoundment, restored stream banks, and riparian area.
Thanks to the lessons learned on several similar dam removal projects, Kleinschmidt’s accelerated schedule was designed to beat the stipulated timeframe, ensuring that the project partners met their funding calendars. This project also came in under budget due to Kleinschmidt’s presence on-site during the construction phase, which facilitated quick design improvements based on conversations between the design engineer and contractor.