ENGINEERING
• Challenges Faced in preparing the Project Design
- Determining of the final reclamation at +2.6mCD
- Removal of unsuitable material from south Crescent and Hotel Island with limitation on removing excessive quantities at minimum costs
- Beach design from limited resources of sand.
- Value engineering exercise carried out for an economic use of rock resulting in the use of 15 different grades of armor and under layer rock.
- Use of three different grades of geotextiles in respect of different grades of rock.
- Design of Toe Bunds and Groynes
- Final plot levels in relation to perimeter rock revetment levels
• Hydraulic Impact
Increase in the sea bed levels due to dredging from north borrow areas required a redesign of the rock revetments, especially at the atoll heads
• Construction Techniques used in Dredging and Reclamation
- To obtain the best available material from a very complex sea bed and predetermined boundaries required excessive numbers of bore holes to be drilled. Further pumping with a dredger of capacity 50-60,000cum/day had limitations in getting the placement for the best material in relation to the location.
- Setting Out for construction of Islands was a challenge as it deviated from the conventional straight to curved boundaries.
- Dredging to minimum depth of -3.0mCD regardless of quality of material
- Reclamation was a 2 stage process with first stage filling taken to about +1.0m CD and the next stage to the final level of +2.6m.
- First stage filling done by using spill barge and the next stage by shore pipe lines with land based equipment. Diffusers were used for control of placement.
• Statistics
- Total dredged volume is 34.0million cum
- 65km of rock revetments
- 1.4million cum or 2.3million tons of rock used in revetment construction
- Length along central axis of Atoll 2.Km, Petal 0.7Km
- Perimeter length of Atoll 4Km, Petal 2.4Km and Hotel Island 7.0Km