During the 16-foot lake drawdown portion of the Lake Oswego Interceptor Sewer Project, Advanced American Construction, Inc. (AAC) was contracted by Lake Oswego Corporation to demolish the existing spillway on Lake Oswego Dam and replace it with a pneumatically operated gate system to control flood waters.
While the lake was drained, AAC increased the size of the overflow section of dam to allow for the installation of the new pneumatic weir. A diamond wire was used to cut 18 each, 35,000 pound blocks which were then removed using a crane and shipped offsite. Post tensioned rods were then drilled and grouted 15 feet into bed rock to account for the reduced weight of the dam. Preparations for the new weir included placing 100 cubic yards of concrete with and extensive system of embedded items, electrical, and mechanical piping. The pneumatic weir is a proprietary system designed and engineered by Obermeyer Hydro, Inc. The system included the weir panels, bladders, seals, compressor, receiver, and PLC controls. Startup and testing of the new system was coordinated with the lake refill.
· Wire saw a portion of the existing dam into 18 each, 35,000 pound blocks for removal.
· Drill and epoxy 176 each rebar dowels to tie in new concrete spillway slab and end piers to existing concrete.
· Form and place 100 cubic yards of new concrete.
· Install 4 each, 7 foot by 20 foot air bladders and 4 each, 10 foot by 20 foot Obermeyer gate panels.
· Mechanical and electrical for gate.