Brighton Dam Rehabilitation
Award of Merit
Owner: Washington Suburban Sanitary Commission
General Contractor: Cianbro
Lead Design Firm, Civil/Structural Engineer: AECOM
Subcontractors: Midwest Mobile (Hydrodemolition); Andrews Equipment (Concrete Pumping); Retro Environmental (Asbestos Abatement); Specialty Underwater Services (Intake Tower Rehabilitation and Cofferdam Installation)
Classified as a high-hazard dam, the nearly 80-year-old structure needed upgrades to prevent a failure that could cause catastrophic consequences downstream. The lengthy list of issues to be addressed included asbestos in spillway joints, extensive areas of weakened concrete, inconsistent bay widths, highly deteriorated Tainter radial-arm gate sections and excessive silt buildup at the intake tower.
Work was plagued by record-setting rainfall. After the project area was flooded five times in six months, the team enhanced existing lean construction approaches to recover lost time, including using a barge-mounted crane and support barges to facilitate Tainter gate repairs from the dam’s reservoir side. That allowed work to proceed in high-water conditions. Similarly, adding twelve 18-in.-dia siphons in specific spillway bays allowed those areas to be upgraded concurrently with the installation of new intake tower sluice gates.
These and other steps more than offset the unforeseen complications of weather and structural deterioration. The 32-month project finished early and under budget. A race to regain time didn’t compromise quality, the team says. Collaboration with fabricators and trades ensured new Tainter gate components and spillway concrete achieved the owner’s exacting performance specifications. A new spillway overlay gives the dam a crisp, uniform appearance, providing an attractive backdrop to an adjacent park and azalea garden.