Repairs to historic Bowersock Dam in Lawrence, KS

Abstract Only - Bowersock Dam was built in 1874 and purchased in 1879 by the Bowersock Mills and Power Co. to harness the energy of the Kansas River to provide electricity for businesses along the river and the Lawrence downtown area in the late 1800's. The city's growth has outpaced the capacity of the dam, and Bowersock Mills currently wholesales its limited power production to Western Resources, Inc. The dam is a concrete structure that is 800 feet in length, with a height of 13.5 feet down to the concrete apron level on the downstream side. The height of the drop between the dam crest and the upstream river bed is about 20 feet. A system of wooden flashboards increases the upstream pool up to 4 feet above the dam crest. The dam is a key component in the City of Lawrence's water supply system. The dam provides the intake crib at the Kaw Water Treatment Plant (WTP) with the necessary submergence to convey raw water from the Kansas River to the WTP for processing. The Bowersock Dam has been deteriorating over the years. Previous inspections along the dam concluded that several critical repairs were necessary to prevent structural failure. The repair alternative presented by Black & Veatch included the replacement of missing or damaged sheet piling, replacement of portions of the concrete apron, placement of underwater concrete, restoration of the downstream riverbed level, repairs to the eroded dam face, and replacement of a membrane for leak control across the dam flashboards. Other alternatives considered were the construction of a new dam, a new intake structure for the WTP, or a groundwater wellfield to replace the intake. These options were ruled out due to various issues including permitting and cost. A complete evaluation of the extent of damage prior to construction was not possible due to problems such as large flows across some of the flashboards, associated diver safety concerns, and slipping hazards. Access from the river became available when the Contractor, L.G. Barcus and Sons, used riprap to be used to restore the river bottom to build a causeway for cranes and equipment. As the causeway construction advanced southward, previously unidentifiable damage to the concrete apron and sheeting was evident. A diving inspection along the southern portion of the dam revealed a 22-foot wide hole that went about halfway into the dam structure. The unanticipated repairs increased the project cost about 40 percent, with overall repairs nearing $2 million. Construction challenges included, but were not limited to weather conditions, US Army Corps of Engineers (COE) releases, the removal of large underwater obstructions during sheet piling, structural integrity and leakage control of flashboards, safety, and unanticipated extra costs to the city.