Engineering Work
Environmental Work
Environmental Pictures
Geomatics Work

Engineering

The South Boca Raton Beach Renourishment Project was constructed between March 28, 2002 and April 5, 2002. The dredge contractor Bean Stuyvesant L.L.C. with the use of the dredge Meridian removed approximately 342,000 cubic yards of sand from the ebb tidal shoal east and south of the Boca Raton Inlet. The dredged material was placed south of the Boca Raton Inlet along the 0.9 mile project area which includes the fill tapers. The average beach width extension was 117 feet, with the largest beach width extension of 168 feet occurring within the middle of the project area. The renourishment was constructed after an interval of six years following the first South Boca Raton Beach Nourishment Project for the City of Boca Raton. Due to the effect of the inlet and inlet jetties, the beach south of the inlet continues to erode, but through continual interior inlet dredging and periodic ebb tidal shoal dredging, this area is maintained. The project manager for the City of Boca Raton is Public Works Director, Bob DiChristopher. The beach renourishment project has performed exceedingly well in providing storm protection to the coastline of South Boca Raton and a feeder beach for Deerfield and Hillsboro Beaches.

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Environmental

Permits issued for the beach nourishment project required the implementation of an ongoing environmental monitoring program focused primarily on the biological monitoring of nearshore hardbottom communities (located seaward of the project equilibrium toe of fill). The environmental investigations of the natural hardbottom habitats were conducted in conjunction with an assessment of juvenile green turtle foraging habitat. The pre-construction, initial post-construction, 1 year post-construction, and 2 year post-construction environmental monitoring survey evaluations comply with the DEP environmental monitoring permit requirements for the beach nourishment project.

Six fixed, one-square meter hardbottom monitoring stations were established on February 14th and 15th, 2002, prior to beach nourishment construction. Four of the stations are located directly seaward of the edge of the project equilibrium toe of fill and two stations are control stations located well beyond the equilibrium toe of fill. In addition to the monitoring stations, two 30 m transects were permanently established at each location for video documentation of the project equilibrium toe of fill adjustment and for the assessment of sea turtle foraging habitat.

The pre-construction (March 13, 2002), initial post-construction (June 3, 2002), 1 year post-construction (April 24, 2003), and 2 year post-construction (April/May 2004) biological monitoring surveys of the monitoring stations and transect lines included a biological inventory and photo-documentation of the epibenthos. The two 30 m transects were surveyed following the AGRRA protocol for benthos. Following AGRRA methodology, a 25 x 25 cm square quadrat was assessed at 3 m intervals along the 30 m transect line. Conditions at the transect lines and monitoring stations were compared to those recorded during pre-construction monitoring.

The overall impacts of the South Boca Beach Nourishment Project on the hardbottom biological community were limited immediately following construction. Comparisons of the pre-construction and initial post-construction surveys revealed little changes in the flora and fauna observed along the western edge of the transects (the area that would be impacted by the toe of fill). The changes that did initially occur took place along the eastern edge of the transects, due to the westerly migration of an offshore sandbar, which is a natural phenomenon.

One year following construction, hardbottom impacts were evident at 4 of the 6 monitoring stations, including one of the two control stations. Impacts may have been the result of an offshore sand source migrating towards the shore, or from the loss of a portion of the advanced fill berm as the beach began to transform to its equilibrium state, or a combination of both. Results from the 2 year post-construction monitoring suggest a landward movement of the ebb tidal shoal as the source of burial.

Investigations at the six locations within and adjacent to the project area exhibited a diverse and productive biological community associated with the nearshore hardbottom area that had little variation in abundance and in species richness from pre-construction to 2 years post-construction. Consistent for low relief nearshore hardbottom throughout Florida, the benthic community within the project area supported flora and fauna common to ephemeral habitats associated with the nearshore environment. Similar to natural sand coverage events, short-term impacts to the benthic community from beach nourishment projects are possible and have been previously documented in South Florida. The extent of any long term or permanent impact remains unclear because organisms in the nearshore community are commonly impacted naturally from periodic burial episodes resulting from storms and shifting sediment.

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Pictures

South Boca Raton Beach Nourishment Project aerial view north of the Deerfield Pier

Nearshore hardbottom monitoring Station No. 1 of the South Boca Raton Beach Nourishment Project

Nearshore hardbottom monitoring Station No. 2 of the South Boca Raton Beach Nourishment Project

Nearshore hardbottom monitoring Station No. 3 of the South Boca Raton Beach Nourishment Project

Nearshore hardbottom monitoring Station No. 5 of the South Boca Raton Beach Nourishment Project

Nearshore hardbottom monitoring Station No. 6 of the South Boca Raton Beach Nourishment Project

Benthic species near Station No. 6 of the South Boca Raton Nourishment Project

Balloonfish (Diodon holocanthus) along Transect No.6 of the South Boca Raton Beach Nourishment Project

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Geomatics

Since 1984, CPE surveyors have been surveying the beach and offshore area of Boca Raton Inlet on a biannual basis for assessment of the inlet management program. Surveys include beach profiles extending one mile on both sides of the inlet and detailed bathymetric surveys of the inlet and ebb shoal. Computer generated contour maps are developed and used in the shoaling assessments. A report is prepared annually which provides an overall evaluation of the management program and makes recommendations for the upcoming year.

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