Due to flooding in August 2018, a section of steel sheet pile (bulkhead) protecting the bank of Baskerville Harbor along Pheasant Branch Creek failed and washed into the channel. This bulkhead retains the bank with homes less than 25 feet from the water. The repair process took considerable time due to the amount of damage the City of Middleton received during the flooding event, working through the FEMA process (for reimbursement), prioritizing projects, and hiring consultants.
raSmith was retained to evaluate and design the repairs to the Baskerville Harbor bulkhead. Upon surveying the site, severe scour and an exposed pipe duct were discovered in Pheasant Branch Creek from Century Avenue to Lake Mendota. Near the toe of the steel sheet pile, scour removed material necessary to support the wall. Given the decreased wall support, raSmith’s structural engineers evaluated the wall’s stability. This project included repairs to the steel sheet pile bulkhead that failed in the channel. New driven sheet pile was used to connect the remaining bulkhead and re-establish it in the same location that existed before the flood damage. Loosened and washed-away sheet pile cap was also repaired. To re-establish wall stability, the project utilized rock to restore the streambed elevation. Rock riprap was used to fill the scour hole around the duct bank. Sheet pile was installed below the channel bed to retain the rock and prevent future channel scour below the duct bank elevation.
During construction, unexpected delays resulted because of the contractor’s inability to acquire specific materials. The flooding also caused many sheet piles to wash out to the bottom of the channel, along with other debris, resulting in the contractor’s inability to drive sheet pile in certain locations. The washed-out sheet piles and other debris were removed from the channel bottom to allow the project to continue.
Learn more about the challenges and multi-disciplinary approach to this project.