The project was to increase the size of the Umm Al Quwain Fishing Harbour to accommodate 300 commercial fishing vessels; providing a protected location with floating marina berths for these vessels, many of which were previously moored ad hoc on the banks of Umm Al Quwain estuary. The harbour also includes a new UAE Coast Guard facility with reporting berths to monitor fishing and boating operations.
Ecocoast was engaged by the Principal Marina Contractor, Al Manzel, to undertake all stages of the breakwater work from the site investigations to the construction supervision.
The site is exposed to moderate-large swells generated over the full reach of the Arabian Gulf. The southern breakwater is adjacent to the prevailing Northwesterly wind and swell, whereas the northern breakwater is exposed to smaller swells generated from the Northeast.
The construction needed to be carried out in the shamal storm season. The challenge was to produce a cost effective design and construction methodology that could be constructed by local contractors during the shamal season without excessive delays and downtime and to keep within a tight budget.
The existing breakwater required the removal of a large quantity of material before the extension on the southern breakwater could progress. Much of the existing limestone rock armour appeared to have bio-erosion occurring due to rock-boring bivalves.
The project involved bathymetric survey, numerical modelling, detailed design and supervision. The final design was developed in close cooperation with Al Manzel and the Client. The final design was in accordance with the UK Rock Manual and included an additional 800m of rock breakwaters.
The rock armour and core material from the original fishing harbour were considered satisfactory for re-use in the new design, with potential environmental benefits resulting from re-using the bio-eroded limestone. Denser Gabbro rock was also utilised in the construction and large 3-6 tonne rock armour was placed on the seaward face of the southern breakwater where the most significant wave action was expected.
Significant cost savings were achieved by:
- Designing to suit the local contracting plant and methods.
- Maximizing the recovery and reusing of existing rock.
- Minimizing the crest width and heights.
- A very high standard of on-site supervision and project management allowing additions, such as a boat slip requested by client, to be included.
Construction management during adverse weather was controlled using a dynamic approach to temporarily protect exposed areas when meteorological models indicated potentially damaging storm events. These storm events were almost a weekly occurrence whilst constructing during the winter “Shamal” season.