USACE Savannah District is on a mission to maintain navigable waterways throughout coastal Georgia

To enable the U.S. Army Corps of Engineers (USACE) to continue maintaining navigable waterways for commerce and recreational activities for the USACE Savannah District portion of the Atlantic Intracoastal Waterway (AIWW).

The USACE Savannah District's portion of the AIWW begins in the north at the Port Royal Sound, SC and extends 161 miles to the south-southwest through Georgia to Cumberland Sound, FL. The authorized depth for this stretch of waterway is -12 ft mean lower low water (MLLW) to provide for the safe movement of goods between major deep draft ports and create the opportunity for safe recreational activities. However, several areas along the AIWW repeatedly sustain significant shoaling and sedimentation that the USACE Savannah District is tasked with monitoring and maintaining.

A shortage of commercially viable and environmentally acceptable disposal areas introduces a challenge when planning maintenance dredging projects along the AIWW. Additionally, providing accurate surveys that can ensure safe navigation of Georgia's ~7 ft tidal range is necessary for the continuance of both commercial and recreational vessel traffic. These challenges reinforce the need for a District-level sediment management plan that quantifies the volumes of sediment available, forecasts future dredging needs, and qualifies the potential sources of beneficial reuse.

The main objective was to characterize the types of sediments along the AIWW, emphasizing locations that have exhibited historically high shoaling rates and will require near-term dredging. The data collected will inform a Dredged Material Management Plan (DMMP) that can be used to advise future AIWW dredge efforts within the Savannah District's area of responsibility. The Savannah District has a particular interest in evaluating if placed material would contain mud aggregates that are less likely to be dispersed throughout the system.

The USACE Savannah District engaged us to undertake a sediment sampling and analysis project. Thirty-four vibracore borings were collected along the AIWW. The recovered sediments were shipped to the USACE Engineer Research & Development Center – Coastal Hydraulics Laboratory, where the contents were homogenized in the sediment laboratory and analyzed for commonly measured physical properties, cohesive sediment erosion, and aggregate durability.

The USACE Savannah District will use the results of this thorough sampling and analysis effort to develop a DMMP of the AIWW and plan for future maintenance dredging and beneficial reuse. The DMMP will ensure the USACE Savannah District can enact its mission to maintain a navigable waterway for commerce and recreation via a well-planned maintenance dredging and beneficial reuse plan.

The USACE Savannah District has already utilized the data GHD collected for multiple maintenance dredging events in the AIWW including Altamaha Sound and Cumberland Dividings.