AWARDED – USACE – NWP – FY 16 – Bonneville Dam Bradford Island Fish Ladder Erosion Repairs
The work included site preparation and placement of rip-rap for armoring a slope that had recently been scoured due to high flows. Site preparation included demolition of a grouted rip-rap layer about 3 feet thick. Grout demolition was performed from a barge mounted excavator with a demolition hammer. Site preparation also included demolition of the concrete slabs indicated on the latest bathymetric survey provided by the Government. The existing rip-rap was removed to the slopes and elevations shown on the plans to allow for placement of new stone in a layer 5 feet thick.
The stone placed was an average weight of 3,000 pounds and diameter of 3.3 feet. 11,500 tons of rock was provided and placed by MIC.
Quality control on grading included surveys before site preparation, after site preparation, and after final stone placement. MIC provided a Blueview scanning sonar to assist in rock placement. Hydrographic surveying was performed by Northwest Hydro.
Work was performed in extremely icy, snowy and windy conditions.