By-Passing and Back-Passing with Reference to Florida

By-passing by natural action is examined with special reference to Florida Inlets. The present status of by-passing plant operations in Florida is reviewed, including the 40-yr-old installation at the South Lake Worth Inlet and the 10-yr-old installation at the Palm Beach Inlet. The existing by-passing arrangement at the Hillsboro Inlet is based on transfer from deposit basin inside the weir section in the updrift side jetty; the planned transfer arrangement at the Ponce de Leon Inlet is based on the same principle. Inasmuch as it is evident that by-passing plants, partly because of the tidal flow that discharges material in the ocean and in the bay and partly as a result of the rise of sea level, will not be able to solve more than a certain part of a beach erosion problem, replenishment by sand from other sources is indispensable. The most logical source is offshore deposits. Material may be brought to shore by back-passing, using an offshore scraper for maintenance or a special hydraulic dredge for major improvements. If the borrow area is located close to shore, the question arises of whether the borrow pit will fill up again with material from further offshore, material from the sides, or material dragged out by waves from the beach. Tests performed on Jupiter Island using an offshore scraper are described briefly.