Evaluation of Environmental Impact Related to Proposed Beach Restoration at Caneel Bay Resort, St. Thomas, U.S.V.I

V.I. Marine Advisors, Inc.

The 1996 hurricane season has left the beaches of Caneel Bay Resort in various levels of disarray. Roots of coastal vegetation are exposed along all shorelines, the worst exposure being at Hawksnest and Turtle Beaches. VI Marine Advisors was asked to evaluate the level of damage, make recommendations for remediation and analyze several possible sand sources for possible renourishment. Seven profiles were established and measured to determine the present character of Little Caneel, Caneel, Paradise, Scott, Turtle and Hawksnest beaches. Sand samples were taken from each profile for laboratory determination of mean grain size and sorting. Samples of sand obtained from Jost van Dyke, Barbuda, the Bahamas and Guyana were similarly analyzed. The nearshore area around the entire resort was examined by snorkeling to identify any potentially sensitive areas that might be damaged by increased turbidity. Based on our field examination, the worst erosion remains in Hawksnest Bay. Roots are exposed along the entire shoreline to the extent that natural coastal defenses are threatened. As no local sand source exists within the bay, outside sand will be needed to cover exposed roots. In Turtle Bay, sand is returning to the beach rapidly. The beach is over steepened to the point of instability. Sand from the uppermost beach berm could be safely moved landward to cover exposed roots. In Scott, Caneel, Paradise and Little Caneel Bays sand had come ashore to varying degrees. In many places, sufficient reserves exist that can be moved landward to cover exposed roots. In some areas, some additional sand may be needed. In particular, the exposed scarp in northeastern Scott Bay has no beach in front of it. If the scarp can be lowered slightly and a small quantity of sand added (ca, 100- 150 cubic yards), this problem can be minimized. Sands from Jost van Dyke and the Bahamas are unsuitable due to their high mud content. The Guyana sand is the optimal choice as 1) Corps of Engineers' tests show it to be stable and 2) it contains absolutely no mud. We have had great success with this sand on St. Croix. Unfortunately, the great distance involved makes this sand both expensive and logistically difficult to import. The Barbuda sand contains on average 2% mud. While this is sufficient to cause an aesthetically displeasing sediment plume over the short term, experience has shown that environmental damage is unlikely. Any sensitive environments that were identified exist some distance from the beaches. Most corals, sponges and other invertebrates are species that have shown considerable tolerance to short-term sediment stress. The only sediment-sensitive coral (Acropora palmata) inhabits distant and higher-energy areas where water motion prevents significant sediment settling and damage. The management at Caneel Bay Resort has devised a plan which focuses on Hawksnest Bay with respect to adding outside sand. Efforts are still underway to identify a realistic supplier for Guyana sand in smaller quantities. If this can be done, Guyana sand will be used, thereby eliminating all environmental concerns. If this is not possible, the Barbuda sand will be stockpiled just behind the beach where it will be washed before being taken to the beach. The site slopes landward and all fine-grained material will be trapped naturally on land. It is anticipated that the mud content can be reduced from 2% to less that 1% by this plan. Some turbidity will still result during placement, but it should be no more significant that that caused by moderate Fall rains.