Memorandum

To:                  Chris Layton, Town Manager

From:              Andy Garman, Director of Community Development

Date:               5/1/08

Re:                  Update on Spring Storm Beach Conditions

 

In the month of April there were a series of storms that had a significant impact on oceanfront properties in the area north of the Army Corps of Engineers research pier.  Town staff identified damage to 32 sets of beach stairs from Sea Ridge to the northern limits of Carolina Dunes (see attached photos).  This includes a number of the subdivision beach accesses.  Several properties in this area are also conducting beach fill projects in order to prevent damage to pools or other accessory structures.  There is also a property owner in Sandhills whose house is now imminently threatened (the foundation is within 20 feet of the erosion scarp) and would qualify for sandbags as a temporary means to control erosion.  This property owner is currently investigating the feasibility of moving the house further west on the property. 

 

This area of the beach has been noted in recent years as being particularly susceptible to erosion.  A significant number of properties lost beach stairs during the Thanksgiving storm of 2006.  Attached is a series of aerial photographs which illustrate the erosion problems in this area.  Staff took the 2002 and 2007 aerial photography provided by Dare County and mapped the first line of stable natural vegetation (FLSNV) from the USACE pier north to the Northpoint subdivision.  You will see that the vegetation line, which typically represents the eastern extent of the crest of the frontal dune, has moved significantly to the west in the past five years.  Some properties appear to have lost more than 50 feet of dune in this time frame.  As you know, we issue CAMA permits for oceanfront development based on an erosion rate calculated by the state.  In this area, the average annual erosion rate is two feet per year; the lowest of the erosion rates currently applied in the Town of Duck.  Over the past five years, the actual erosion rate in this area appears to be anywhere from seven to ten feet per year.  A two foot erosion rate would yield a 60 foot setback for structures from the FLSNV based on the state formula for calculating the setback.  In theory this is designed to provide a structure with a 30 year life, which coincides with the typical amortization schedule of a conventional mortgage.  Based on the actual erosion rate, houses in this area if built to the easternmost extent of the setback could be threatened within six to ten years of the date of initial construction.  The house in the Sandhills subdivision that is now imminently threatened was built in 1999.  What is interesting and also somewhat disturbing is that this problem appears to be isolated to this section of the Town.  At the upcoming meeting staff will present a larger map of the entire Town to show changes in the vegetation line over the past five years.  Based on a preliminary review, it appears that the vegetation line is relatively stable north of Carolina Dunes and south of the pier.  We have discussed the possibility that the pier is increasing the rate of erosion in this area.  We have scheduled a meeting with USACE staff to discuss this problem on May 23^rd.  In the interim we will continue to collect information to document this problem and brainstorm measures to deal with this issue. 

 

Attachments:     April 2008 photos of beach stair damage

                        2002 aerial photography with 2002 and 2007 FLSNV

2007 aerial photography with 2002 and 2007 FLSNV