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Erosion of sandy beaches is a worldwide problem that elicits innovative geoengineering techniques to reduce adverse impacts of shoreline retreat. Beach replenishment has emerged as the "soft" shore-stabilization technique of choice for mitigating beach erosion. This method of shore protection involves the addition of sand to the littoral sediment budget for sacrificial purposes. Because inland sand sources are often uneconomical or impractical to use, and known nearshore sources are limited, finding adequate quantities of suitable sand on the inner continental shelf is often vital to beach replenishment projects. The technical studies of survey and materials analysis that identify and delineate usable sand sources are sometimes almost as expensive as small-project dredging, pumping, and placing the sand on the beach as fill. Inadequate quantity or substandard quality of shelf sand, as well as often-prohibitive overhead expenses, thus compel shoreline managers to seek suitable sand sources offshore. In the study area off the central-west coast of Florida, offshore potential borrow areas (PBAs) were identified on the basis of studies conducted in reconnoitory and detailed phases. Sophisticated state-of-the-art equipment used in this investigation provided more detailed subbottom mapping information than is normally obtained with conventional seismic equipment. An example of sand exploration studies was incorporated in a 215-km super(2) survey of offshore areas by conducting bathymetric surveys and subbottom seismic profiling, collecting jet probes, grab samples, and vibrocores, and analyzing sediment grading in subsamples from vibrocores. These combined analyses indicated that at least 8.8 x 10 super(6) m super(3) of sand is available in potential borrow areas from 7.0 to 12 km offshore in water depths of 8.0 to 11.5 m. In the PBAs, mean grain size of sand falls into the range 0.13-0.53 mm, sorting averages 0.65-1.31 phi , and the overall silt content varies from 3.9-8.5%. High silt contents (13-19%) mapped in some areas make these sedimentary deposits unsuitable as fill for artificial beach renourishment.

For coastal managers, localized areas of accelerated shoreline retreat, often referred to as erosional 'hot spots,' are problematic because of their small size and high costs associated with remediation. These focal points of intense erosional activity commonly occur immediately downdrift of stabilized (jettied) navigational entrances and natural littoral drift barriers. Whatever their cause, hot spots require emergency fill to temporarily stabilize the beach. The application of processed glass cullet to erosional hot spots is a new, innovative, and evolving technology that has potential for emergency shore protection along developed shores. Proxy of recycled glass aggregate as beach fill has several advantages which include: (1) use of a cost-effective recycled product, (2) application of an environmentally safe (inert) material, (3) selection of preferred grain sizes and shapes by crushing and sieving glass cullet, (4) performance which meets hydrodynamic requirements for reducing site erosion, and (5) admixture of glass aggregate which approximates the density, durability, compaction, permeability, and color of native beach sand. Florida annually recycles about 170,000 m super(3) of glass cullet, of which 30% to 40% is available for alternative uses. Based on 500 m sub(3) of processed glass sand (crushed and sieved to -30+60 mesh grain size), material costs average about $2.70/m super(3) compared to $12.56/m super(3) for natural upland sand. Materials, overland delivery, and placement costs compare favorably with dredged offshore sand along the Florida southeast coast which averages about $11.80 per m super(3). Currently there is about 25,000 m super(3) of glass cullet available in Palm Beach, Broward, and Dade counties for erosional hot-spot control on beaches.