Background and Objectives
Holetown Beach is characterized by two fringing reefs, which have a significant influence on the environment of the site, both in terms of marine biology and coastal processes (waves, currents, sand transport). Sand transport along this stretch of shoreline is intermittent and there is limited sand supply. The net transport rate is southward driven by the northerly swells. These conditions have historically resulted in down drift impacts (on the south side) when long shore perpendicular structures are constructed (greater than 20 to 30 m in length).
The following key objectives were developed through discussions with the CZMU, Steering Committee, and other participants during the course of this project:
- Develop continuous public access along this reach of shoreline.
- Expand the recreational beach where feasible.
- All coastal structures are to be carefully designed to avoid affecting alongshore transport processes and related impacts to adjacent beaches and reefs.
The focus of all final design efforts for this project has revolved around the objectives noted above while attempting to maintain the construction costs within the proposed budget. A combination of the objective of minimizing environmental impacts and the coastal environment (wave exposure, sand transport processes) has driven the design process resulting in the recommendation for only nearshore small scale structures. The resulting design meets all of the objectives. There are no offshore structures negating direct impacts on the fringing reefs. The proposed shoreline structures, including the two headlands, are relatively small and extend only a short distance from shore. The proposed facilities therefore provide continuous access along this reach of shoreline, an expanded recreational beach, and do not impact the adjacent or downdrift reefs.
It is important to recognize that the complex coastal environment at this site will generate dynamic beaches which will respond to various events including both northwesterly swell events and infrequent hurricanes and tropical storms. The proposed headlands will provide for the minimum level of protection required to maintain a recreational beach; however, the beaches will be in dynamic equilibrium and have a periodic requirement for re-nourishment in response to significant wave events. The proposed structures will continue to provide shore protection to maintain a stable shoreline. Finally, the estimate of probable construction costs for the proposed structures is under the proposed project budget.
Physical Modelling
One of the key components of the final design process for the Holetown Beach improvement project was completion of a 1:20 scale physical model.
The Holetown Beach model was undertaken to assess design alternatives to provide continuous access along the shoreline, as well as improved beach amenity, and to support detailed design development of the preferred alternative. The model, undertaken at a geometric scale of 1:20, included the simulation of approximately 950 m of shoreline, including existing shoreline structures (revetments, seawalls and beaches) along the Regent, Chefette, Baku and Tides properties. The underwater bathymetry was simulated out to the –8 m LD contour, including the nearshore fringing reefs and pocket beaches between them.
Detailed analyses and interpretation of the physical and numerical model results, as well as consideration of planning, aesthetic, environmental and construction issues, have supported detailed design development for the project, as documented in the permit drawings. Final design documents (plans and specifications) are being prepared.
Construction Methodology
The south headland, revetment and walkways will be constructed first. The placement of sand on the beach will be initiated as soon as the first section of the revetments from Chefette to the south side of the south headland is completed. This will minimize any potential impacts of construction related to the alongshore transport of sand.
The majority of materials will be delivered as required and immediately placed in the works. The exception may be additional sand. We have requested that the CZMU find a suitable location to stockpile additional sand material for beach replenishment following construction and the beach profile adjustment, which is expected in response to storms. We would like this stockpile to be located as close as possible to the site so that it can be readily moved onto the beach following a storm event.
The equipment will generally work on top of the core material for the walkway prior to walkway (concrete top portion) construction. As the stone revetment sections are completed the walkway, seatwalls and curb will be formed and poured as the contractor retreats.
The final construction work will include the revetment, walkways, and headland to the north of Chefette.
All construction work will be contained within the footprint of the proposed structures. Access is anticipated through the north side of the Chefette parking lot.
