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1992-319 CZM Section II (8.0) 8.0 BEACH NOURISHMENT 8.1 Introduction The beaches of Collier County are one of the County's most valuable natural resources, and must be preserved. Many people are attracted to collier county because of the white sandy beaches along the Gulf of Mexico. The Gulf beaches provide recreation and pleasure to residents and tourists alike. Tourism is a major industry in Collier county and is necessary to its economic well-being. In 1988 an estimated $500 million was spent in Collier county on tourism and recreation, much of which was beach related. The county's beaches provide recreation, protection of upland properties, and wildlife habitat. Beaches provide protection to upland properties from storm damage. A healthy beach system provides a buffer to the energy produced by storm driven waves. Waves lose energy through friction and percolation as they move up the beach, thus reducing the severity of damage to structures and properties located further inland. Plants and wildlife also benefit from a healthy beach system. Dune grasses and other vegetation help anchor and stabilize the dune systems. Shorebirds roost, nest and feed in the dunes, and endangered sea turtles require beaches for nesting activity. The present quality and availability of the beaches is declining. Erosion has reduced the width of many beach areas by more than 100 feet since 1973 (Harvey et al., 1984). As erosion continues, the limited area available for recreational use will continue to decrease, and the threat of damage from a major storm will increase. Further, the loss of dry beach and natural dune system drastically alters the ability of coastal wildlife to feed, nest and survive (Coastal Engineering Consultants, Inc., 1988). Extensive measures will be required to protect and enhance the shoreline against the detrimental effects of erosion and the inexorable rise of sea level. A natural beach system is subjected to many natural forces. "Whether deposition or erosion will be predominant in any particular place depends upon a number of interrelated factors, the amount of available beach sand and the location of its source, configuration of the coastline and of the adjoining ocean floor, and the effects of wave, current, wind, and tidal action. The establishment and permanence of natural sand beaches are often the result of a delicate balance among a number of these factors, and any changes, natural or man made, tend to upset the equilibrium" (Holmberg and Garfinkel, 1985). A healthy beach, II -478- although temporarily vulnerable to storm driven destructive power, has an inherent rebuilding capability to restore its natural equilibrium. The increased supply of sedimentary materials picked up and relocated from remote bottoms may be made part of the littoral transport system that nourishes the beach. This, in turn, nourishes the on-shore dune system that provides permanent protection from storm damage (Holmberg and Garfinkel, 1985) . Natural factors, such as storms, are not the main source of lasting beach erosion, although they may be drastically manifested in a short period of time and at particular sites. Man made structures, such as jetties and groins, interfere with the natural equilibrium of the beach and sea, and are the prime source of our erosion problems (Holmberg and Garfinkel, 1985; Leonard et al., 1988; Stephen, 1982). Since one side of a jetty is attached to the shore, the longshore currents that cannot move over the obstruction in their paths are diverted seaward. Some sand is deposited on the side of the jetty meeting the current. The rest of the material still in the flow is carried away from the beach, and thus out of the littoral system. The gradual loss of tremendous amounts of beach has become a serious concern to the people living in coastal areas. Beachfront property is usually very expensive and people often go to extreme lengths to protect these properties against the steadily encroaching sea. This usually entails the building of seawalls or some other type of barrier to fend off oceanic forces. Seawalls may afford some protection from erosion to land behind them but actually exacerbate the problem to the beach in front. Seawalls increase the current flows by forming a hardened parallel shoreline. The energy absorbing effect of a gradually rising beach is lost. Unimpeded waves strike upon a hardened surface with no absorption or dissipation of energy. Wave energy is thereby reflected and converted to scouring power and increased velocity of the current running along the shore. This scouring action often cuts a channel or trough in the sandy bottom parallel to the seawall. The trough then pulls sand from the adjoining beach causing greater loss of the energy absorbing beach profile. Waves continue to sweep in with increasing energy as more and more of the beach is flattened. Eventually the scouring action at the seawall front undermines the integrity of the structure, causing it to collapse. This may then open the once protected upland area to rapid and often destructive erosion by the unimpeded sea. This was dramatically demonstrated during the "No Name" storm of June 18, 1982 where seawall failures caused evacuation and condemnation of condominiums; private homes suffered undermining of foundations, and public roads on several islands were closed due to collapse, undermining, and flooding (Stephen, 1982). II -479- Beach management plans must be enacted to protect and enhance the County's receding shoreline. In the past 25 years beach replenishment has increased as a management response to shoreline recession (Leonard et al., 1988). When properly designed and executed, replenished beaches offer many advantages over mechanical means of preventing beach erosion. On a large scale, beach nourishment is less costly than coastal armoring structures. Long reaches of shoreline can be protected at less cost per linear foot by building beaches as opposed to revetment. An advantage to this method is that nourishment directly remedies the basic cause of most erosion problems, a deficiency in natural sand supply, and benefits rather than damages the adjacent shore (u.s. Army Corps of Engineers, 1977). Beaches act to dissipate energy, breaking down the organized kinetic energy of ocean waves rather than increasing it as seawalls do. A well-designed replenished beach system is also aesthetically pleasing, and provides increased recreational enjoyment to residents and tourists. Similarly, the area's natural resources are enhanced by providing additional habitat for native wildlife. Ultimately, the primary concern with beach nourishment projects is financial responsibility. These projects are often very expensive, costing millions of dollars. Although there are funds available from State and federal sources, most of the cost will come from local financing. Due to the fact that the property owners refused to allow additional pUblic access to the beach, the current Marco Island Beach renourishment project is totally funded by local financing. A Municipal Services Taxing Unit (MSTU) was enacted in which all the beach front property owners were assessed an additional 1.5 mills to their ad valorem taxes to fund the project. Obviously, beach-front property owners cannot be expected to totally finance the nourishment of all the County's beaches. Instead, assessments can be made County wide, based on Benefit Units, as was done in Captiva (Giannino et al., 1985). In this way, those who benefit the most from the renourished beach, such as beach-front property owners and hotels, pay the most. Many factors must be considered when designing a beach nourishment project. A thorough understanding of all the physical processes affecting the designated area is of prime concern. All too often an expensive beach nourishment project is washed away with the next major storm event, or the grain size of the nourishing material is too fine, and is carried down stream by littoral transport to be deposited on neighboring beaches. When a renourished beach and dune system is properly built, the whole community benefits. wide sandy beaches attract more tourist dollars to the area, provide increased recreational space II -480- for the residents, and protect valuable upland areas from storm damage and erosion. The revegetated dunes offer new habitat to birds and other wildlife, and provide a more pleasant beach atmosphere. 8.2 criteria Protection and conservation of the coastal environment is a difficult task because of the dynamic nature of the shoreline. Various schemes have been developed to maintain the integrity of the coastline such as construction of breakwaters, seawalls, groins, jetties, and beach nourishment. Many of these shore protection strategies have failed due to lack of sufficient knowledge concerning the relation between sediment dynamics and the controlling physical processes (Zarillo et al., 1985). The construction of "hard" structures, such as jetties, interfere with the natural equilibrium of the beach by interrupting the littoral forces, and are likely to increase erosion of the shoreline (Holmberg and Garfinkel, 1985; Leonard et al.,1988; stephen, 1982). Beach nourishment has become the preferred method of beach erosion control. This type of coastal protection can add sediment to a sediment deficient system and can act as a "soft" storm protection structure. A beach selected for this type of erosion control in Collier County must meet three important criteria. The most important is preservation of upland real estate. Over the past two decades a great deal of construction has taken place along the County's coastline. Much of this construction consists of high-rise condominiums and expensive single family housing. These properties represent a very large portion of the County's tax base and would suffer greatly during a major storm event. The second criterion in beach nourishment is enhanced recreational beach activities. Preservation of ample beach area for present and future recreational need will protect the County's tourist based economy. The third consideration is the rebuilding of an aesthetically pleasing shoreline, complete with a revegetated dune system, that is compatible with the natural environment. Beach nourishment has increased in importance as a tool to combat shoreline recession, but this solution may only be temporary. Some beach nourishment projects have restored beaches for many years, whereas other projects have remained in place for only a few months. The success of any beach nourishment project depends on a number of factors that determine how the finished project will result. The cost of beach nourishment projects typically runs into the millions of dollars. State and federal laws require that beach projects be designed by licensed professional II -481- engineers. Engineers normally charge upwards of 10% of the total project cost for design and permitting fees, giving them a built-in incentive for big dollar projects (Palm Beach Post, Dec. 2, 1990). To justify these fees, engineering firms must be held accountable for the project outcome. Too many times poor engineering has resulted in millions of dollars worth of sand being pumped onto a beach only to have the next major storm wash it all away, leaving the taxpayer with a big bill to pay and no beach. There are many aspects to a beach nourishment project that must be weighed before a contract is awarded. Engineering firms bidding on Collier County beach nourishment projects must address specific fiscal, environmental, and socioeconomic parameters in the preparation of their project proposals. Although the accurate quantification of these parameters is the subject of final engineering design, their formulation can be reliably accomplished in sufficient detail for the purposes of project planning, financial analysis, and selection of a preferred alternative. Recent hydrographic studies will be required to determine changes in the shoreline as well as the nearshore and offshore areas. Beach width and profile measurements along with aerial photography will be necessary to set a baseline for future comparisons. An accurate sand budget and littoral study must be performed to demonstrate coastal processes. Most importantly sediment studies must be conducted in the offshore borrow areas to insure beach fill compatibility. Monitoring programs must be built into project proposals. Although the Florida Department of Environmental Regulation (FDER) requires some monitoring, their guidelines are often vague or cover wide parameters. Collier County must insist on more rigid and localized monitoring. Reporting should be required for pre-nourishment, as-built, and post-nourishment surveys on three, six, twelve, twenty-four and thirty-six month intervals. Monitoring transects and sample sites should be set up using the the Florida Department of Natural Resources (FDNR) benchmark system. This will provide for long term replicate measurements. The final contract for beach nourishment projects must contain language that will insure that the County receives the beach for which it pays, and that the desired product will last for a reasonable period of time. The engineering firm that certifies a beach nourishment project must be willing to accept all responsibilities associated with the construction and subsequent effects of the completed project within a reasonable time frame. Measurements of beach nourishment and time frames should be specified in the beach nourishment contract. II -482- 8.3 Bnviromental Considerations Artificial beach nourishment projects involve many environmental concerns. These projects impact a wide range of habitats and may disrupt the physical processes affecting the littoral currents along the beaches. To alleviate these concerns, certain guidelines should be put into effect at the onset of a project to insure adequate safeguards. When discussing environmental aspects of beach nourishment it must be remembered that we are dealing with an extremely harsh and unstable environment. This area is inhabited by a relatively small number of different plants and animals (low diversity but high abundance). The terrestrial plants are adapted to salt spray and desiccation, occur generally on the dune line and landward, and are not normally impacted by beach nourishment. The dry beach is inhabited permanently by very few species; the most noticeable are birds, crabs, and humans. However, this area is utilized by endangered sea turtles for nesting, and the potential exists to adversely impact nests with beach nourishment. The offshore environment is the first area that may be negatively affected. Dredging sand from offshore borrow sites can have serious and long lasting effects if certain guidelines are not followed. A complete biological and hydrographical survey should be undertaken at and around the proposed borrow areas prior to dredging. The biological survey will determine the existence of any live bottom communities that will be adversely affected by a dredging operation. The pre-nourishment hydrographic survey must include sediment core sampling to at least the depth of dredge scouring. This will determine if the sediment is compatible with the beach sediment and the clay/silt content. The amount of clay/silt contained in the sediment will indicate the amount of turbidity that can be expected during the dredging and also what will be washed out from the beach once the fill has been put in place. Turbidity, or the amount of suspended material, has the most unfavorable effect on benthic life forms. A survey immediately after project completion of the same parameters will establish a starting point for borrow area behavior. The post-nourishment survey and subsequent monitoring surveys of surface sediment samples will identify the change in sediment characteristics as the borrow area recovers. The post-nourishment biological surveys will demonstrate the rate of recovery of the benthic communities disrupted during the dredging II -483- operation. The number and location of samples should be the same throughout the monitoring period. Control areas should be established north and south of the borrow areas for comparison. organisms inhabiting the intertidal zone are inevitably buried during a beach nourishment project. The intertidal zone is a high energy area characterized by instability (from seasonal sediment erosion and accretion and major physical changes from storms). The intertidal zone migrates onshore with erosion and offshore with accretion. The inhabitants of the surf zone are predominantly burrowing marine animals: clams, crustaceans, and worms. They are specially adapted to this harsh environment and recover quickly after major natural disasters such as storms and red tide. Nelson (1985), Stauble and Nelson (1985), and Turbeville and Marsh (1981) report no lasting effects to intertidal fauna caused by beach restoration. However, post-nourishment monitoring should document the recovery of these areas. Seaward of the intertidal zone, where the substrate is always submerged and waves touch bottom less frequently, the environment is more stable. This stability provides a more hospitable habitat which is used by a variety of marine animals, including many varieties of fish. Relative to the other beach areas, this littoral zone is the most diverse and productive in marine systems. In Collier County, sea grasses, worm reefs and exposed rock occur in the littoral zone. These resources are used by other marine life as places of attachment and refuge, further increasing diversity and abundance. Wherever these enhanced resources occur adjacent to the intertidal zone, they are in jeopardy of being damaged by storm events and beach nourishment. No beach nourishment activity should take place between May and October, or during the turtle nesting season. Engineering firms must allow ample time in the planning and mobilization stages to insure that work is completed during the eight months when the turtles are not actively nesting. Care must also be taken so as not to interfere with other endangered species such as the manatee and least terns (see Sections 6.1, 6.2, and 6.3). A properly designed and constructed nourished beach and dune system will provide enhanced shoreline protection, increased recreational area, and a restored beach environment. Much of the Collier County coastline is receding either due to the effects of erosion or sea level rise. A well engineered and prudently constructed project will offset the gradual loss of valuable beach front and furnish the County with an enhanced natural resource that can be enjoyed by all. II -484- Recommendations Priorities should be established for approval of beach nourishment projects. Approval of these projects should be based on: 1. preservation of upland real estate, 2. Enhancement of recreational beach area, 3. Re-creation of an aesthetically pleasant and naturally compatible system. Beach nourishment projects should be considered more appropriate for shoreline protection than shoreline armoring. Sand should as closely as possible match the natural grain size distribution. Monitoring programs should be required after beach nourishment projects to determine the success of the project. Measurements and analyses should be required at a minimum of three, six, twelve, twenty-four, and thirty-six months after completion of the project. Nourishment activities should be planned well in advance to avoid the turtle nesting season. The area below the dune should be tilled to reduce compaction which may interfere with sea turtle nesting. Contractors responsible for the design of beach nourishment projects should be responsible for the success of beach nourishment projects. II -485-