A marine site investigation at Walls is to be carried out prior to the building of a new pier, the harbour board decided at a special meeting on Thursday.
A jack-up rig will be employed at the site to take core samples, thus obtaining accurate site information which will allow sheet piling to be ordered in the correct length.
The proposed new pier will be a curved structure with berthing space for around six vessels within it and larger vessels being able to use the outer face. The existing pier will remain in place.
The council had already allocated £100,000 in the 2009-10 capital programme to develop Walls Pier and decided on the comprehensive marine site investigation (MSI) rather than taking the risk of progressing to detailed design stage and assuming, but not ascertaining, ground conditions.
Most of the cost of the MSI is in bringing the specialist equipment to the site and it is therefore intended that investigation into the Whalsay ferry link should be carried out at the same time.
The lowest tender for carrying out site investigation at Walls, if done in conjunction with the Whalsay work, is around £65,000.
Other estimated costs up to project tender stage, which include environmental consultant fees, consent fees, land acquisition and design and tender preparation, take the figure up to £150,000. This exceeds the budget already allocated, but additional budget is likely to come from underspends in the Uyeasound harbour development and the Scalloway water main project. The estimated construction phase costs are £3,350,000.