Hunting Island State Park Beach Restoration Project 17 May 2016

Project Setting 2

Hunting Island is ~ 4 miles long Heavily influenced by St Helena Sound Project Setting Hunting Island is ~ 4 miles long Heavily influenced by St Helena Sound Loss of 1,000-2,500 ft between 1857 and 1979 Volume loss of around 300,000 cy per year Eight previous nourishment projects totaling over 5 million cy 3

Over 2,000 ft of Erosion along north end of Hunting since 1850’s Historical Shoreline 1857 1920 1933 1964 1971 1987 2000 2011 Over 2,000 ft of Erosion along north end of Hunting since 1850’s Harbor southern accretion accelerated in ~1970s – over 2,000 ft accretion 4

Previous Project 2006: 570,000 cy nourishment (Design) 2006 Hunting Island 2006: 570,000 cy nourishment (Design) 2007: Construction of 6 groins in three “clusters” Required post-project monitoring of downcoast impacts 5

Sand Searches & Borrow Areas 2006 Plan 2006 As-built

Strategic Nourishment for Groins Three Recreation Areas Long-Term Erosion Rate = ~25 ft/yr Nourished Seven (7) Times Prior To Project Project Completed On Time Within PRT’s Budget Feb 2006 June 2006 Feb 2007 7

2005 2007 2008 2010 2011 2012

Project areas gained ~561,000 cy during nourishment Island-wide Changes Volumetric Erosion Rates Project areas gained ~561,000 cy during nourishment Same areas still hold 414,000 cy in 2015 Net loss of 147,000 since nourishment Erosion rate decreased in areas updrift of groins from ~18 cy/ft per year to <5 cy/ft per year 9

Cabin Road Area Changes Groin 8 South 2004-2009 2009-2015 10

Hunting Island Conditions ~9 years post installation 6 7 8 11

Existing Conditions 2016 ~9 years post installation

Plan Purpose Proposed Project Nourishment of a total of 10,400 lf of beach Maximum Nourishment Volume = 630,000cy Two Nourishment Areas – Campground, North-South Beach Two new ~450 ft groins (#2 and #5A) Two potential offshore borrow areas No work north of groin #1 or along south end Purpose Restoration of beach area Reduction of erosion rates Protection of park infrastructure Restoration/Protection of beach habitat

Project Plan

Project Plan

Proposed Project Plan Nourishment will occur in winter months (outside of turtle nesting season) “Piggybacking” project with Edisto Beach to reduce costs Groin construction will occur during or immediately after nourishment Monitoring proposed including shorebird surveys, lighting surveys, beach topography surveys, aerial photos, sediment analysis, downdrift impact Anticipated construction length ~4 months

Additional Actions Proposed Project Completion of a Biological Assessment (this week) Completion of an updated Downdrift Impact Assessment Additional geotechnical data collection Pre construction surveys and monitoring