INTERIM OPERATION PLAN (2017) - Project Updates

SUMMARY & HOW TO INTERPRET THE PROGRESS MAP
for Interim Operation Plan

Great Lakes Dredge & Dock will be utilizing their cutterhead-suction pipeline dredge, the Illinois for the 2017 Interim Operation Plan effort.  A cutterhead-suction dredge utilizes a crane situated on a barge that positions the cutterhead, which looks like a gigantic drill bit, along the seafloor.  The cutterhead agitates the sandy bottom, and the resulting slurry of sediment and water is subsequently suctioned into a long tube transitioning into a pipeline that can be extended to a specific target area (beach, upland disposal site, etc.).  Pipeline dredges are usually not self-powered, but are towed to the dredging site and secured in place by special anchor pilings, called spuds.  Additionally, a water-based booster pump (GLDD #4) will be utilized for the Interim Operation Project to provide additional power to pump dredged sand for a maximum distance of approximately 4.25 miles extending from the channel westward close to the Circle.     

Project engineers use “stations” positioned along the beach to monitor construction progress and to verify in-place volumes of sand placed on the beach by dredging contractors. The progress map above provides a detailed view of the project reach to be completed in winter/spring 2017 with the location/identification of the station numbers.  The shaded areas in red represent the completed portions of the project and will be updated on a weekly basis throughout the construction.

The station numbers included in the progress map conveniently correspond to thousands of linear feet along the beach. For instance, the distance between station “25+00" and “85+00” on the graphic above is 6,000 feet. If you visit the beaches of Ft. Macon and Atlantic beach this winter, you may see wood or metal stakes at the base of the dunes that will identify these station numbers by 100 feet intervals as “33+00", “34+00”, etc.

The total estimated volume of shoal material to be excavated/dredged from the Morehead City Harbor is 667,000 cubic yards (cy) = 500,000 cy + 167,000 cy supplemental - mostly from the area known as the "Cutoff".  As a mental image, a loaded dump truck can hold roughly 12 cy (wet) or possibly 15 cy (dry) of sand.  The contract price is $9,435,825 ($7,435,825 +$2,000,000 supplemental) and the average fill density is expected to be close to  70 cy/ft = 667,000 cy/9,500 linear feet.  The environmental window for the effort closes on April 30, 2017, and the contractor is required to complete the project by this date.