Port Lewes Shoreline Rehabilitation & Dune Reinforcement
Over the years, the Port Lewes Homeowners Association noticed that the small portion of accessible beach within their community had experienced numerous events where storm damage had caused significant erosion and shoreline damage. Several of the events were so extreme that portions of the townhouse structures closest to the beach access area were in danger of becoming compromised. They had previously installed a stone revetment to protect a portion of the shoreline adjacent to the beach area. That solution has enjoyed success in much of that area since approximately 2007, but the beach access area was still in danger during storm events.
Davis, Bowen & Friedel, Inc. (DBF), provided topographic surveying, permitting assistance, coastal engineering design, bidding assistance, and construction administration services for the Port Lewes Homeowners Association on this project.
In 2012, the HOA had the coastal engineering team look at the existing stone revetment closest to the beach access area and it was determined, based upon a wind and wave analysis, that a rehabilitation would be necessary for a small portion of that shoreline to provide protection for that area. That stone rehabilitation/extension work was completed. However, the adjacent beach area was still in danger during large storm events.
Once again, Port Lewes HOA turned to DBF to develop additional measures to protect the beach area and the adjacent townhouse structures. The HOA had already spent a considerable amount of money, continually replacing sand that would wash away in large storm events. They were looking for a solution that would reduce the amount of storm damage but retain the beach access in that area. Several options were investigated and analyzed for durability, constructability, and cost effectiveness. Ultimately, a compromise between beach replenishment and structural reinforcement were developed.
The center of the dune was to be reinforced with a sheeting wall to reduce the amount of sand that could be washed away during a storm event. A wave overtopping and scour analysis was performed and the details for the dune reinforcement and beach replenishment were developed. This required various permits from the Delaware Department of Natural Resources and Environmental Control (DNREC). These permits included the following:
• Application for Construction Seaward of the DNREC Building Line
• Application for Letter of Approval for Placement of Sand or Fill
• Application for Construction Letter of Approval for a Pedestrian Dune Crossover
Ultimately, the dune reinforcement consisted of a sheeting wall with a “Reno Mattress” on the landward side located in the mid-point of the dune. In addition, another sheeting wall was installed parallel and closer to the townhouse structures. This serves as a secondary line of defense in the event of exceptionally large wind and storm events. This should prevent the erosion of sand near the townhouse structures. These improvements are mostly beneath the surface of the dune, with only a timber cap and decorative post and rope system along the top of sheeting wall being visible most of the time. This allows Port Lewes to maintain a natural beach access while protecting the dune and the nearby townhouse structures. The existing stone revetment was repaired and was wrapped into the sheeting wall. The dune was graded to blend in naturally with the adjacent dune near the adjacent property. The beach access area was limited to 6’ wide to prevent additional foot traffic on much of the dune area.