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Title: Final Environmental Assessment : Maintenance Dredging Intracoastal Waterway Reach I and Portion of Reach II, St. Lucie County, Florida
Authors: United States. Army. Corps of Engineers. Jacksonville District
Keywords: Dredging
Dredging spoil
Intracoastal waterways
Saint Lucie County (Fla.)
Publisher: United States. Army. Corps of Engineers. Jacksonville District.
Abstract: The U.S. Army Corps of Engineers (Corps), Jacksonville District, is proposing to conduct periodic maintenance dredging of the St. Lucie County, Florida portion of the Intracoastal Waterway (IWW) in the vicinity of Ft. Pierce Inlet. This would include all of Reach I (as defined in Taylor et al., 2000) which extends from the Indian River/St. Lucie County line (IWW mile 218.46) southward 8.80 miles to Bear Point (IWW mile 227.27) and the northern mile of Reach II to IWW mile 228.27 (see Figure 1, Project Map). Dredged material would be placed in the previously constructed Dredged Material Management Area (DMMA) SL-2 located about 3,300 ft south of the Indian River/St. Lucie County line (about seven miles north of Ft. Pierce). SL-2 is designed to accommodate the projected 50 year Reach I dredged material storage requirement of 78,116 cubic yards (cy). The federal channel would be maintained to its authorized dimensions of 125-feet wide by 12-feet deep plus 2-feet of allowable over-depth at mean low water (mlw) from the County line south to the Ft. Pierce Harbor Project turning basin (IWW mile 225.24), and -10 ft MLW from that point southward. The accumulation of sediment, commonly referred to as shoaling, has restricted the width of the project channel and significantly reduced its depth. The most recent examination survey documented a total in situ shoaling volume of 69,057 cy within the authorized channel. Minimum depths recorded from the project channel are less than 7.1 ft causing navigation problems for commercial and larger recreational vessels. Some commercial vessels that utilize this segment of the IWW require at least 9-feet of draft. Vessels are currently being forced outside the authorized channel in search of deeper water, waiting for high tides, or prop dredging through the channel. Specifically, the large ocean going research vessels of the Harbor Branch Oceanographic Institute (HBOI) have incurred several thousands of dollars in damage from hitting the shoals (FIND 2008). Removal of the shoal material would maintain the navigable capacity of the project channel.
Description: Environmental Assessment
Rights: Approved for Public Release; Distribution is Unlimited
Appears in Collections:Environmental Documents

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