Helix Energy Spool Base
HDR provided a wide range of services including site selection, planning, permitting, off-site mitigation, and civil and marine design for Helix Energy, an international deep-sea pipeline contractor in support of their approximate $25 million pipe spooling base. Multiple challenges were overcome in order to begin operations in 2009.
Varying sizes of pipe-lay ships and barges created challenges for optimizing bulkhead height and configuration of breasting/mooring structures. Vessel maneuvering practices and mooring line configurations were coordinated with the ships' captains, refining the mooring analyses for the vessels. The bulkhead height and mooring structures layout needed to accommodate low and high profile pipe ships, while balancing site elevation earthwork requirements and the height/depth to mud line of the bulkhead sheet pile.
Another challenge was designing bulkhead sections and fenders to withstand reactionary forces at the base of the berth while ships spool one-mile long welded pipe stalks onto the aft of the ships. The foundations of the down ramp's concrete sidewalls were designed to transfer the forces placed on the fenders while spooling pipe.
Lastly, large crane loads placed at the face of the bulkhead had to be accommodated.
Preliminary design plans helped identify prospective contractors for civil-site works and marine works. Competitive bids based on preliminary construction documents were solicited and final design was completed in conjunction with the contractor's input.