LAKE CUSHMAN FSC NTS
In early 2014, Coastwise Marine Design and Tullio Celano P.E. were hired by Dix Corporation, the general contractor, to provide launch, blocking , ballasting, temporary mooring and rollover plans for the Lake Cushman, WA Floating Surface Collector and Net Transition Structure, the two large floating structures that will be used for salmon aquaculture in the lake. The entire project is funded by Tacoma Public Utility. as a result of a settlement between the city, the Skokomish Tribe, state and federal agencies.
The FSC was designed by Elliot Bay Design Group of Seattle , WA. The NTS was designed by Deere & Ault Consultants of Boise, ID. Both structures were fabricated by Thompson Metal Fab in modules, trucked to the construction site at the shore of the lake and assembled. NW Structural Moving is the contractor responsible for moving and launching both structures.
Tullio Celano P.E. convinced the contractor that it would be significantly less expensive to assemble and launch the NTS upside down, then roll it upright in the lake as the alternative to costly falsework, scaffolding and crane barges needed for upright assembly and launch. The rollover was performed using buoyant and weight forces only by flooding several pontoons on one side. Excessive pressures were mitigated by a system of temporary internal bracing and/or foam flotation. Coastwise Marine Design was on site to lead the rollover process.
Coastwise Marine Design created detailed 3D models of the FSC and NTS in Rhino, weight estimates and reserve buoyancy calculations in Excel. CMD provided the ballast plans. Tullio Celano provided hydrostatic simulations with GHS and roll speed and pressure calcs with Excel.
