Port Rodie PS Outfall


ABCO Marine Ltd were contracted by Leslie MWH JV as specialist marine contractor on Port Rodie, Pumping Station Outfall for Scottish Water. Working with RPS we supplied a design & build package, including temporary works design for a cofferdam installation, for retrieval of directional drill head. The design work also included pipe ballast, backfill and diffuser section.

Our Site Team prepared the outfall pipe lengths on location in Stranraer, with the pipe welded into three lengths. The first length, a 100metre string in support of the directional drilling operation was managed with the support of the C57 Red Squirrel, located at the cofferdam. The two marine sections of pipe lengths were connected into one continuous string via a 45dgree bend leading to the installed cofferdam. The prepared pipe string was sunk into the excavated marine trench using the ‘float and sink’ method of pipe installation, with stringent controls for alignment. 

Project Information

800mm Outside Diameter Pipe and associated diffuser fittings were placed from Ch-0+170 on shore via ch-0+270 ‘Cofferdam Installation’ (LWM) to the diffuser outlet point at Ch0+800.

ABCO designed and supplied all ballast, scour protection and backfill materials utilised in the project, including concrete collars/mattress and granular backfill material and diffuser protection.

Dredging Activity and time of the year required the mobilisation of the C59 Jack Up Platform c/w Long excavator, Tug and support vessels to support the marine excavations through sands, gravels, with material side cast for backfill. Excavation of trench in 10msw (Metre Sea Water), using long reach excavator, with level control maintained from GPS dig system.

The piling process, located in the intertidal zone adjacent to the rail track required the mobilisation of the C57 Jack Up platform c/w crawler crane and piling systems.

Pipe length was prepared on location, with all pipe welding, concrete collaring and connections completed on site. The pipe strings prepared and positioned, in advance of the ‘float and sink’ installation of pipe into prepared marine trench.

Trench backfill incorporated, prior diver installation of terram and a stone surround for the entire length of the installed pipe in advance of final back filling with the as dug materials.

Hydrographic and topographical surveys of the existing seabed and beach were completed, hydrographic survey were also utilised during the project, and both pre/post sink surveys of the marine trench.

ABCO Divers Ltd – commercial diving company, supported installation of diffuser systems, scour protection and shore tie in process.


Leslie MWH JV for Scottish Water


December 2014 – March 2015

Client Representatives

Mr Kenny Jones, Leslie MWH JV


Long Sea Outfalls Overwater Piling

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