Frequently Asked Questions
South Amelia Island 2021 Beach Renourishment
Frequently Asked Questions and Answers | May 2022
SAISSA has successfully completed a third maintenance beach renourishment of the South Amelia Island Shore Stabilization Project (SAISSP). This renourishment:
replaces the advance fill sand that has eroded since the last renourishment project in 2011;
protects the dunes and vegetated dune habitats that have developed on the landward portion of the beach since the initial restoration project in 1994; and
restores the recreational amenity value of the dry sandy beach area.
SAISSA, along with its project partners -- Nassau County, Florida, and the Florida Park Service -- received a permit from the Florida Department of Environmental Protection (FDEP) and a U.S. Army Corps of Engineers (USACE) permit. SAISSA completed the beach renourishment in the spring of 2022.
1. “Why was the project performed 2021-22?”
By design, beach nourishment projects are intended to be soft, or sacrificial, solutions to beach erosion. Sand placed for beach nourishment is expected to erode over time and be replaced periodically through renourishment. SAISSA’s first project, the initial beach restoration, was constructed in 1994. The first maintenance renourishment was conducted eight years later in 2002. The second maintenance renourishment was constructed nine years later in 2011. The third maintenance renourishment has been completed in early 2022, just over ten years after the last project. During the 27-year life of the project, the time between renourishments, referred to as the renourishment interval, has lengthened from eight to ten years.
Professional survey comparisons of the 2020 beach conditions to the 2011 conditions revealed that 80% of the placement volume from the 2011 project has eroded from the placement limits, which extended from the 2011 vegetation line seaward to approximately the -8ft depth contour. It is projected that by summer 2021 the advance fill berm overall will have lost 90% of the 2011 placed volume. Some of the eroded sand lies in deeper water offshore of the SAISSA beaches, while the remainder of the lost sand has been carried away alongshore, primarily into Nassau Sound.
These percentages represent the overall volume of the beach nourishment project. The northern portions of the project have lost in excess of 100% of the advance fill berm, while portions of the south-central area of the project have a portion of the 2011 advance fill berm remaining. At present, the loss of the advance fill berm is eroding the seaward face of the dunes along a majority of the project shoreline. Along the northern portions of the project, the dune erosion is occurring in an area that is landward of the 2011 landward limit of fill placement.
SAISSA has successfully maintained the entire length of the project, which was renourished all together in one project effort for economic and project performance reasons. Likewise, the construction of a beach nourishment project requires a great deal of planning and preparation, from both a physical engineering/environmental aspect and from a financial standpoint. SAISSA has taken substantial efforts to coordinate the construction project and develop a financial plan to pay for the beach renourishment project, including the coordination of cost-sharing grants that significantly reduced the overall cost of the project to the members of SAISSA.
2. How long does a renourishment take to complete?”
The beach renourishment typically requires 3-4 months to complete. Work began at the southern end of Amelia Island near the rock breakwater and proceeded northward at a rate of roughly 150-200 ft per day. For safety, the contractor closed off segments of the beach only where sand placement was actively occurring. The remainder of the shoreline remained open to the public. The beach fill placement occurred 7 days per week, 24 hours per day, so that the project was completed as quickly as possible. It is noted that there was construction noise associated with the project, but any one location on the beach was affected for just a few days as the work advanced northward along the beach.
3. “The beach looks good to me; how can it be eroding?”
Yes, the beach looks wonderful! But south Amelia Island is an eroding shoreline, as documented historically by the FDEP (1) and years of monitoring for SAISSA by professional surveyors and engineers. The current condition of the SAISSA beaches is the direct result of the beach nourishment projects implemented and maintained by SAISSA since 1994. The sand placement has provided a protective buffer from storms and a great source of wind-blown sand to allow the dunes to grow along the length of the project. These dunes host sea oats and other plant species that help to maintain the protective dunes.
However, while those dunes have grown, the sand fill along the beach had eroded at a faster rate over the renourishment interval of the previous project. As an example, along the beach near the South County Beach Access, the beach fill had lost roughly 140 cubic yards of sand per alongshore foot of shoreline between 2011 and 2020(2). That equates to more than nine dump-truck loads of sand eroded along every foot of the shoreline in that area. Of that eroded volume, roughly 3% had blown into the dunes during that time, equivalent to one-third of a dump-truck load of sand for every foot of shoreline. Another 15% of the eroded sand, roughly 1.5 truck loads, had migrated offshore along that profile into waters deeper than the 2011 placement area.
Without the recently completed maintenance renourishment, the dunes would lose the supply of wind-blown sand and the natural erosion processes would have progressively eroded into those vegetated dunes. This erosion was observed most recently in the Fall 2020 nor’easters.
1 Foster, E.R., Spurgeon, D.L., and Cheng, J., 1999. “Shoreline Change Rate Estimates, Nassau County, FL,” Report BCS-99-04, Florida Department of Environmental Protection, Office of Beaches and Coastal Systems, Tallahassee, FL.
2 Olsen Associates, Inc., 2020 “Year-Nine Post-Construction Monitoring Report (2011-2020),” Report and data submitted to Florida Department of Environmental Protection and SAISSA. Example values refer to volume changes at monument R-72.
4. “How do our beaches compare to other areas of Amelia Island?”
At present, the beaches of South Amelia Island are in a good condition, due to the continuing maintenance of the beach nourishment project. While the width of the sandy beaches and the width of the vegetated dunes varies along Amelia Island, at this time the beach conditions along the SAISSA project limits compare favorably in terms of beach width and volume to other areas of the island, and it is highly desirable to maintain that status.
It should be noted that there are three distinct beach zones along the island: (1) Fernandina Beach, generally from the St. Marys River jetties southward past Sadler Road; (2) the central portion of the island (the Ritz-Carlton, Peters Point Park, Scott Road access, Summer Beach, Ocean Village, American Beach); and (3) south Amelia Island.
Of the three zones, the north and south beaches experience ongoing erosion, and have historically been erosional, while the central beaches of Amelia Island are quite stable. The northern beaches at Fernandina Beach are frequently nourished by the U.S. Army Corps of Engineers as part of the ongoing maintenance of the St. Marys River entrance channel. The central beaches along the middle of Amelia Island are not regularly nourished, and in fact have not received any direct sand placement since the early 1990s. The south beaches have been maintained by SAISSA efforts since 1994.
5. “Don’t the SAISSA beaches receive sand from Fernandina Beach?
A short answer to this very complicated process is “Not exactly, not consistently, and not nearly enough.” As discussed above, the south beaches of Amelia Island continue to erode, despite decades of sand placement at Fernandina Beach. This fact is clearly demonstrated with the survey data collected annually for several decades along the beaches.
It has long been thought, without validation, that sand from the beaches of Fernandina Beach moves southward along the Amelia Island shoreline toward Nassau Sound in what people refer to as a “river of sand” along the beach. Numerical modeling and beach survey measurements over the last 20 years, however, have indicated that this concept greatly over-simplifies sand movement along Amelia Island. During times of nor’easters, sand certainly moves southward all along the Amelia Island shoreline. Similarly, during the passage of typical storm fronts and tropical storm events, sand can move either northward or southward all along the Amelia Island shoreline.
When assessed over several years, however, it is revealed that, in the net, sand placed from the ongoing nourishments of Fernandina Beach either a) remains on the beaches in Fernandina Beach, or b) migrates southward to the center of the island, thereby further promoting the stability of the middle of the island. As mentioned above, the south beaches along the SAISSA project continue to experience erosion and that erosion is only offset by beach nourishment.
6. "Where does the sand for the renourishment come from?”
Sand for the beach renourishment was dredged from the ebb shoal of Nassau Sound off the south tip of the island. Unlike prior projects, the 2021-22 borrow area will resemble more of a tidal channel through a portion of the ebb shoal, versus an offshore pit located along the outer fringes of the same ebb shoal. This design is intended to mimic the natural meandering tidal channels that exist upon the ebb shoal. In fact, the borrow area lies along an area that was a natural channel less than 20 years ago. That natural channel has since infilled with sand eroded off the beaches of Amelia Island. The 2021-22 borrow area “channel” is expected to infill in a similar manner over a period of several years, such that it could be used for future renourishments.
As an aside, there are very few areas of the seabed offshore of Amelia Island that contain large volumes of beach-compatible sand. As revealed by hundreds of sediment core-boring samples collected over many decades by numerous researchers, the vast majority of sediments found within a reasonable offshore distance from Amelia Island can be described as very fine quartz sand mixed with excessive percentages of silts and muds, along with various levels of crushed shell. Conversely, sand along the Amelia Island beaches is predominantly fine quartz sand mixed with varying levels of shell. Note that the sand placed along Fernandina Beach is material dredged from that navigation channel and the ebb shoal of the tidal inlet. Similar to the 2021 borrow area at Nassau Sound, these materials have had the benefit of sorting and “washing” by waves and tides in the nearshore and inlet shoals.
7. “But won’t the borrow area disturb the natural beach processes?”
No. As described above, the borrow area lies atop the Nassau Sound ebb shoal off the south end of Amelia Island and is designed to mimic the natural processes of the meandering tidal channels that exist naturally in the Sound. SAISSA’s consultants performed comprehensive analytical and numerical modeling studies of the proposed dredging to assess the potential effects of the dredging and found no significant impacts related to the project. These studies have been reviewed by FDEP and USACE, as well as a third-party engineering firm on behalf of the Florida Park Service. The ebb shoal at Nassau Sound contains tens of millions of cubic yards of sand, and the project will dredge only a small fraction of that volume. Further, the dredged borrow area is expected to infill after dredging, in part from sediments naturally eroded off the Amelia Island shoreline
It is noted that there have been beach nourishment projects constructed in the past, although not at Amelia Island, where the dredge borrow areas have been sited too close to the open-coast beach, including projects that have been located within the active beach profile itself. These projects, sited at seabed depths above the typical “depth of closure” along the active beach, typically represent only a transfer of sand from the lower portions of the active profile to the upper beach profile versus an addition of sand from an external source. That is not the case here, where the borrow area is located off the south tip of the island and within the ebb shoal complex of the tidal inlet. That said, the borrow area is in an active area of the ebb shoal, and this is intentional to allow the borrow area to fill in with beach-compatible sediment following the 2021 dredging.
8. “Does the sand from the borrow area have shell in it?”
Yes, it does. The material in the 2021-22 borrow area consists of quartz sand and pieces of shells of varying sizes, including the occasional whole shell, and is very similar to the sediments currently in place along the SAISSA beaches. The material to be dredged in the 2021-22 project consists predominantly of fine quartz sand, comprising roughly 75% of the material in the borrow area. The remaining 25% of the material is calcium carbonate, or shell, of varying particle sizes. Most of the shell particles are very small pieces of shell, such that only 3.4% of the overall borrow area sediments are larger than about 5 millimeters in size. These larger pieces are pieces of shell, typically called shell hash, and some individual whole shells. The FDEP provides rules for the nature for dredged sand used for beach nourishment. The Department has reviewed the geotechnical data from the borrow area and has agreed that it meets the rules provided in the Florida Administrative Code.
This combination of materials was intentionally sought because it will better resist the natural erosional forces along the project length and thereby remain on the project beach for a sufficiently long length of time to make the beach nourishment program economically effective. Such has been the case since the 1994 project, where it was recognized that coarser material would be needed to build a viable beach nourishment project.
9. “What about the sea turtles, won’t this project harm them and their nests?”
No, the project does not harm sea turtles or sea turtle nests. The project was constructed during sea turtle nesting season, as were the three previous projects. Amelia Island Sea Turtle Watch (AISTW) members monitored the shoreline each day during construction and relocated sea turtle nests laid in areas that would be affected by construction. Sea turtle protection and the relocation process is highly regulated by the project permits and has been proven statewide to be very successful.
AISTW has provided sea turtle monitoring data dating back to 1990 for the south end of Amelia Island. During that 30-year period, the SAISSA project shoreline has experienced a significant and consistent increase in sea turtle nesting, due in part to the increased sea turtle nesting habitat provided by the beach nourishment project. In the last five seasons (2016-2020), the SAISSA project shoreline has averaged more than 48 sea turtle nests per year, or roughly 16 nests per mile of beach. That is compared to the five-year period prior to beach restoration (1989-1993) where nesting averaged less than 10 per year (less than 4 nests per mile).
10. “I heard SAISSA has plowed up sea oats along the beach. Is that true?”
No significant amount of dune vegetation has ever been impacted by the beach nourishment projects and their subsequent maintenance. SAISSA has gone to great lengths to protect and maintain the beach, which fosters dune growth and dune vegetation growth. The “plowing” that has been referred to by some is actually a process called decompaction and is a mechanical process in which a tractor equipped with tilling tines is used to loosen the hydraulically-dredged and placed beach sediments prior to sea turtle nesting season for the first few years following construction. The decompaction of the beach fill is a permit requirement imposed by the U.S. Fish and Wildlife Service and the Florida Fish and Wildlife Conservation Commission. This decompaction process avoids dune vegetation to the maximum extent possible, such that no significant amount of dune vegetation is impacted by the project maintenance, and the level of dune vegetation has increased over the life of the project since 1994.
11. “Will this project help us with sea level rise?”
Yes, the maintenance of the beach and dune system, and the simple placement of beach fill sand itself, will greatly help to offset the effects of sea level rise along the Atlantic Ocean shoreline. This project will not, however, guard against the effects of sea level rise along the marsh side of Amelia Island.
Beach nourishment has been demonstrated to be an effective mitigation strategy against sea level rise effects, as the sand along the active beach profile can be transported upward by waves and tides along the beach in response to increases in water level. Dr. James Houston, Director Emeritus of the U.S. Army Corps of Engineers Coastal Hydraulics Laboratory has conducted significant research in this particular area, including providing research results for Nassau County.
In a recent article (3), Dr. Houston describes the relationship between beach nourishment efforts and projected sea level rise in the State of Florida (no other erosional forces were considered). The intent of the paper was to illustrate that if the rates of beach nourishment in Nassau County that have occurred since 1988 continue in the future, the sand placement can more than offset the effects of sea level rise, even in the most severe of sea level rise scenarios.
A few important caveats, however, are provided. Houston’s article considers Amelia Island as a whole and uses island-wide average values. Also, the rate of sand placement and nourishment has decreased since 1988. Lastly, it is important to recognize that Houston’s 2020 article only relates the effects of sea level rise and beach nourishment; it does not consider the significant effects of erosion caused by other forces that affect the beaches in Nassau County, such as changes in the alongshore transport climate. In a related article (4) and personal communication with Dr. Houston, for Nassau County, the negative effects of shoreline change due to longshore transport are more than twice the negative effects of projected sea level rise “at the upper uncertainty limit of the worst IPCC [Intergovernmental Panel on Climate Change] scenario.”
3 Houston, J.R., 2020. “Beach nourishment versus sea level rise on Florida’s coasts,” Shore & Beach, Journal of the American Shore and Beach Preservation Association, Ft. Myers, FL, Vol. 88 #3, pp 3-13.
4 Houston, J.R., 2019. “The fate of beach nourishment sand placed on the Florida East Coast,” Shore & Beach, Journal of the American Shore and Beach Preservation Association, Ft. Myers, FL, Vol. 87 #2, pp 3-14.
12. “My property is not in a flood zone. Why should I be concerned?”
Most properties along the oceanfront are sited at elevations above any FEMA flood zone designation. While this may indicate that these properties are not significantly at direct risk from floodwaters, such designations do not mean that the properties are not at risk from erosion, shoreline/dune retreat, and possible undermining due to dune losses. The original beach restoration in 1994 was prompted in large part by landward dune retreat at such properties as Windsong and The Retreat. Accompanying that dune retreat was storm-related flooding adjacent to the higher elevation areas. Subsequent beach nourishment efforts in 2002 and 2011 have successfully maintained the sandy beaches along the project length to preclude threats to the dunes and upland infrastructure. The proposed 2021 project seeks to maintain that status. At the same time, the maintenance renourishment project is also intended to protect the recreational amenity value.
13. “How do you track the sand on the beach over time?”
The performance of the beach nourishment project is tracked by annual beach monitoring surveys. Comparing each annual survey to prior surveys provides a means of calculating shoreline and beach volume changes over time. These surveys reference range survey markers called R- monuments, established along the beach by the FDEP back in the 1970s. The R-monuments are spaced roughly 1,000 feet apart along the open coastline of Amelia Island. Over time, the SAISSA monitoring system has added additional reference points at 500-foot intervals along the southern end of the island from the Sanctuary to Nassau Sound to improve the resolution of the surveys and provide a better description of changes in the beach.
Surveys at each reference marker follow the cross-shore “beach profile” in survey transects that extend from the dunes across the dry beach and seaward out to deep water, roughly 25 to 30- foot depths offshore, with points collected at varying distances along the beach profile to accurately capture the elevation and shape of the profile along that survey transect.
Surveys are collected by a professionally licensed surveyor with extensive hydrographic survey experience. The upper dry portion of the beach is surveyed by a land-based crew using state-of-the-art GPS units. The land crew will survey the dunes out to a wading depth at low tide. Conversely, the offshore portion of the surveys is collected by a boat crew, also using state-of-the- art GPS equipment that eliminates the effects of the time-varying height of the tide. The boat crew extends the water-based portion of the survey landward into the tidal zone at high tide in order to overlap the survey data with the land crew’s wading survey data. These two efforts occur within days of one another to provide an accurate snapshot of the entire beach profile at the time of the survey.
To track beach performance, changes in the position of the Mean High Water Line or any other elevation of interest can be directly compared to calculate shoreline (or beach width) retreat or advance. Volume changes are calculated between different year profile surveys to determine the sectional volume change, measured in cubic yards per foot of alongshore beach at each survey marker. By using the ‘average end-area method’ the total volume between two adjacent survey transects can be calculated.
Other methods exist to capture survey data along the beach. For upland and clear-water uses, GPS and laser-based Light Detection and Ranging systems (LIDAR) systems are becoming more and more prevalent. These plane-, helicopter-, or drone-based systems can provide high- density survey data in a short period of time. However, applications of LIDAR systems in dark- water systems, such as along the Amelia Island shoreline, are of limited applicability in surveying the submerged portions of the beach profile.
Regarding the use of LIDAR data: While having more data would always be welcomed in the coastal monitoring program, it is not clear that have the additional spatial density or increased temporal frequency of data would alter any of the conclusions made by coastal engineers regarding sediment budgets. The benefit of collecting additional data would need to be weighed against the additive cost of collection. It is opined the FDEP, which is a cost-sharing partner in the SAISSP construction and monitoring and reviews the monitoring and other data each year, would not necessarily approve of a significant increase in surveys (and hence increase in cost).
14. “Who manages the beach nourishment project for SAISSA?”
The 2021-22 beach renourishment project was designed, permitted, and managed by Olsen Associates, Inc. (OAI), of Jacksonville, Florida, a coastal engineering consulting firm with decades of experience in coastal engineering projects on Amelia Island. OAI was selected as the prime professional for the project in 2012, based upon a publicly advertised Request-for-Qualifications (RFQ) process administered by Nassau County in keeping with the county’s procurement regulations. OAI’s contract was renewed in 2017, following a review of performance and contract terms. OAI has been the prime professional and Engineer of Record for dozens of beach nourishment projects in Florida and around the Southeast U.S. Dr. Albert Browder, P.E., one the principal engineers for OAI, is the permit agent and Engineer of Record for the 2021-22 project. Dr. Browder is a licensed professional engineer in the States of Florida and Alabama, and has been the Engineer of Record and permit agent for numerous beach nourishment projects in Florida, including Pensacola Beach, Longboat Key, and, notably, the 2011 Amelia Island renourishment project.