A Replacement Outfall for Peterhead

The paper describes the design and construction of an outfall into Sandford Bay, Peterhead, on a highly-exposed stretch of the NE coast of Scotland.
The outfall forms part of a drainage system that was installed in the early 1970s to reduce pollution in Peterhead Bay and to accommodate increased flows from oil-related development. It replaces the original outfall, which failed in 1979 due to wave action.
Stability of the new steel-pipe outfall, which was installed by the bottom pull method, is ensured by burial within an excavated rock trench, backfilled and armoured with graded stone.
The exposed location of the site was demonstrated during construction work when bad weather and adverse sea conditions delayed completion by one year.
The paper concludes that the full significance of prevailing sea and weather conditions, and consequently reduced working 'windows', should be taken into account in the planning and programming of outfall work, to reduce the risk of damage to a partially completed and unprotected outfall.