Islandkeeper

Corps Admits Laws of Physics Apply to Alabama (maybe) 

by Glen Coffee

Mar 21, 2018

During a February 22, 2018 public meeting, the Corps of Engineers made a startling admission, something we have known for years and continued to bring to their attention.  Previously, the Corps would never admit that its dredging and disposal practices are interrupting the natural flow of sand from Fort Morgan to Dauphin Island.

The Corps admitted that 50% of the Outer Bar Channel dredged sands placed in the so-called Sand Island Beneficial Use Area (SIBUA) are accumulating and not being reincorporated into the natural littoral drift system.

Since 1999, when the SIBUA began to be used, this has robbed Dauphin Island of at least 7 million cubic yards of beach quality sands, causing significant erosion of the island.

Civil Engineer Richard Brewer recently made the following statement concerning this issue:

When we think of Dauphin Island's erosion, we usually think of only the 7 inhabited miles that stop at the end of the road. However, there is another 7 miles of the island beyond that point that are also suffering from erosion.

If the 7,000,000 cubic yards were spread to a depth of 3 feet, it would cover an area 852 feet wide along the entire 14-mile length of the island. What a beach that would create!

Admittedly, shoreline restoration projects must also consider offshore water depths, etc. Nevertheless, this illustration does allow one to gain a better understanding of how large a volume 7,000,000 cubic yards actually is.

This impact will be made worse each time the Outer Bar Channel is dredged in the future. The Corps should cease referring to the SIBUA as a “beneficial use” disposal site because neither Sand nor Dauphin Island benefit from its use. More importantly, the Corps must identify an alternative disposal site to place dredged sands in shallow water less than 20 feet deep to assure dredged beach quality sands are effectively bypassed across the Outer Bar Channel to be reincorporated into the natural littoral drift system.

The Corps can accomplish this under the authority provided by Section 302 of the Water Resources Development Act of 1996, with the Mobile Harbor Federal Standard being adjusted accordingly as already directed by Corps higher authority in its May 30, 1997 directive to the Mobile District.

Federal law, the Council on Environmental Quality's National Environmental Policy Act regulations, and the Corps' own agency policy and regulations require significant adverse project impacts be MITIGATED.

Based on the Corps’ admission that use of the so-called SIBUA is actually contributing to the erosion of Dauphin Island, the Corps must include in the June Mobile Harbor Draft Report an appropriate MITIGATION PLAN to compensate for at least 7 million cubic yards of beach quality sands that have been removed from the nearshore littoral drift system since 1999, creating an indirect adverse project impact that has significantly contributed to the erosion of both Sand and Dauphin Islands.

Further, the Corps’ recent admission also gives strong credence to the Corps' 1978 report that first concluded maintenance of the Outer Bar Channel contributed to Dauphin Island’s erosion.

The Corps has consistently refused to address in the ongoing Mobile Harbor Study the erosion effects resulting from the cumulative removal of around 30 million cubic yards of sand from the littoral drift system since 1980 associated with the maintenance of the Outer Bar Channel.

In view of its February 22 admission, the Corps has no credible reason to continue advocating it present position and should begin immediately to investigate MITIGATION REMEDIES in the ongoing Mobile Harbor Study to appropriately respond to this now acknowledged significant “changed condition and adverse project impact” in the Study Area.

The existing Mobile Harbor Study provides the Corps with sufficient authority to move forward in MITIGATING the significant adverse erosion impact created by the Mobile Harbor project that the Corps has long refused to acknowledge was occurring.

The Corps, the Port Authority of Alabama, and our elected representatives in Montgomery need to do the right thing for Dauphin Island.  This "stolen" sand needs to be placed closer to the island where it can migrate on to the beaches and help to heal Alabama's ONLY barrier island.