- Departments I - Z
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- Preservation Plan
- Background (< 2010) - Brandt Island Pump-Outs
Background (< 2010) - Brandt Island Pump-Outs
Site Map (2007)
Fact Sheet (2007)
Archived Construction Updates (2004-05)
Fact Sheet (2005)
PROJECT BACKGROUND AND FUNDING
The U.S. Army Corps of Engineers (Corps) Dredge Disposal to Eastern Bogue Banks is part of the maintenance program implemented for the Morehead City Harbor Federal Navigation Project. In order to understand the procedures associated with this nourishment effort, a brief review of dredging operations associated with the Morehead City Harbor Project is necessary.
The aerial scope of dredging operations at the harbor is divided into five regions known as Range A, the Cutoff, Range B, Range C, and the turning basin. Historically, the Cutoff and Range A (collectively known as the outer harbor) have been maintained by hopper dredging that collects sediment from the base of the channel and travels to one of two offshore areas located 1 to approximately 2.5 miles offshore to dispose the dredged material. Maintenance and construction of Range B, C and the turning basin (known as the inner harbor) has been conducted utilizing a pipeline dredge that carries sediment from these areas to the confined upland disposal site of Brandt Island, located north of Fort Macon State Park.
View Graphic: - Harbor Map Diagram
Because of the limited capacity of Brandt Island and the absence of other suitable upland disposal site areas, dredged material is temporarily stored on Brandt Island for a period of 8 to 10 years, or until the island is “full”. Once the capacity of Brandt Island is reached, the material stored in the island is transferred to a beach disposal area located along the eastern portion of Bogue Banks to create accommodation space in Brandt Island for future dredge spoils. The procedure that includes the final removal of material from Brandt Island is commonly referred to as a "pump-out". The disposal area includes the shorelines of Ft. Macon and Atlantic Beach. During major construction improvements (channel deepening), inner harbor material has been piped directly to Bogue Banks Beaches concurrently with the Brandt Island pump outs. The disposal of dredged material to eastern Bogue Banks is the least-costly option for the Corps and thus no costs are incurred by the County or individual municipalities.
Dredged material has been deposited on the shorelines of eastern Bogue Banks in 1978, 1986, 1994, 2002, and 2005. The sources of dredged material in the inner harbor, and hence Brandt Island, are from adjacent beaches, ebb-tide delta sediments from the Beaufort Inlet, riverine sediments of the Newport and North Rivers, and estuarine sediments transported from adjacent sounds and wetlands. Commonly, riverine and estuarine sediments are muddier in size than the sandier sediments derived from adjacent beaches and Beaufort Inlet. On average, 69 percent of the inner harbor spoils are beach quality. In the past all material, regardless of grain size or composition, has been utilized for beach disposal activities. The graphic and table below depicts the geographical extent of beach nourishment throughout time and volumetric rates.
View Graphic: - Pumpout Map Diagram
|HISTORICAL BEACH DISPOSAL VOLUMES|
|Volume (in cubic yards)|
|1,179,600 (piped directly)|
|4,168,600 (94% pumped from Brandt Island, 6% piped directly)|
|4,664,400 (53% pumped from Brandt Island, 47% piped directly)|
|209,348 (piped directly)|
|2,920,729 (82% pumped from Brandt Island, 18% piped directly)|
|184,828 (piped directly)|
*Note - A conventional dump truck holds approximately 15 cubic yards.
A preponderance of clay and fine-grained silt (mud) encountered during the 2005 pump-out failed to meet engineering parameters envisioned for the project in addition to aesthetic and biological expectations by the public and resource agencies as well. The fine-grained sediment settled at a less than desirable slope during construction and the material was dark gray, raising aesthetic concerns. Much of the mud balls and fine-grained material initially placed on the beach have since been sorted and have either been displaced out to sea or reside within the beach berm. Pioneer vegetation has since colonized the beach and sea turtles have nested along the beach in 2005. The extent of these sediments is approximately one mile along the 3.5 miles of beach that was nourished with Brandt Island sediments.
Following the 2005 Brandt Island disposal project, the Corps elected to construct a dike within the island to act as a partition, separating beach-compatible material from muddy sediments dredged from the inner harbor. The beach-compatible compartment will be utilized for future disposal events.
Photos from 2004-05 Pump-Out
Photos from 2007 "Direct Pipe"