Army Corps Reports on Seawall Issues

CAPE MAY – The intersection of Beach and Wilmington avenues presents a particular challenge for the protection offered by Cape May’s seawall. It is a point of specific vulnerability in the city’s east end.
The Army Corps of Engineers decided to study this problem as part of a program that allows the corps flexibility on small projects that do not require congressional authorization. The projects in this program are capped at $10 million.
Army Corps representatives from the Philadelphia District reported their finds to Cape May City Council June 4.
The study considered the condition and existing height of the current seawall, the manner of water flow that tops the seawall, the position of pumping stations, and the relationship of property to the expected water flow near this portion of seawall.
The presentation stated that economics heavily influences the corps in considering solutions under this small project program.
“Any potential solution must be justified by economics,” said Adrian Leary, the corps’ project leader.
The study began with the expectation that the seawall east of Philadelphia Avenue to Wilmington Avenue was lower and more susceptible to “overtopping.” It found that not to be the case.
A significant part of the problem at this intersection is the much shorter distance between the seawall and the ocean.
The federal beach project has attempted to increase the sand in the area during replenishments, but the natural motion of the ocean quickly removed that extra sand. 
The impetus for the study was the experience of Hurricane Sandy. For the study, the corps used coastal storm simulation modeling software to see the levels of potential protection at various seawall heights.
Leary noted that the “sweet spot was at 17 feet.” What that means is that up to 17 feet elevation there was a discernible cost benefit in terms of expense versus protection offered. “After 17 feet that benefit began to decline,” he said.
The project under consideration involves about 400 linear feet of seawall as the wall makes the turn at the Beach and Wilmington avenues intersection. The current seawall at the intersection is at 13 feet when one considers both the concrete wall and the sand barrier above it.
Leary said that a structure at that elevation would require 8 feet of width to ensure stability. Some consideration may be given to potential secondary functions for the 8-foot wide flat top of the proposed seawall.
Leary indicated that the presentation was still in its conceptual stages. The report’s finding and recommendations will go to other groups within the Army Corps for further review and potential modification.
Any final recommendation from the corps would also go through a review process which would include a period of public comment.
To contact Vince Conti, email vconti@cmcherald.com.