The proposed work consists of constructing an ocean outfall structure for an existing stormwater collection system that currently outfalls through eleven (11) beachfront outfall pipes. In detail, the project involves the construction of a stormwater outfall system consisting of dual 84-inch diameter pipes, terminating approximately 1,500 feet into the Atlantic Ocean at a nozzle system that will be armored with ¾ to 1 inch bedding stone, Class “B” rip rap, and armor stones for a total of 270 cubic yards of stone. The proposed outfall system will replace the existing eleven (11) beachfront outfall pipes. The proposed outfall pipes will be installed by dredging a trench within a coffer dam/sheet pile structure and sidecasting the material adjacent to the trench. The temporary sidecast area will be approximately 50 feet wide located immediately adjacent to both sides of the trenched area. The total quantity of dredged material to be sidecast is estimated to be approximately 34,650 cubic yards. The dredged trench will be approximately 30-feet wide in the coffer dam and 1,300-feet long. (Note: The open trench will be backfilled immediately after the placement of several sections of pipe). The project will utilize a temporary trestle with the dimension of 30’ wide and 1,432’ long to facilitate access for cranes and material during construction. The trestle will be utilized by cranes to complete the dredging operation and construction. The temporary coffer dam system will be installed in approximately 300-foot sections. After installed, each coffer dam section will then be dredged to the proper depth. Within the open trench, filter fabric and bedding stone will be installed first. Then a section of outfall pipe will be lowered into the trench and placed at proper grade. After the pipes are installed, the pipes will be covered by a layer of stone and then backfilled. After the trenches are backfilled, the applicant proposes to leave, any excess dredged material in the ocean and allow littoral drift and wave action to disperse the material to re-establish original contours. Upon completion of the construction activities, the temporary coffer dam and trestle will be removed in their entirety.
Note: The proposed facility is within the project area of a Federal Civil Works project: Reach 2 of the Myrtle Beach Shore Protection Project.