Cooling Water Intake Decommissioning at Methil Power Station, Fife, Scotland
Scottish Power embarked on a significant decommissioning programme, within which EDS was contracted to remove and make safe the cooling water intake system.
The coal-fired Methil Power Station, located at the mouth of the River Leven in North Fife, had been out of service for some time. As part of the wider decommissioning programme, EDS was tasked with removing and ensuring the safety of the cooling water intake system.
Scope of Work:
- Dismantling and removing the offshore inlet tower and infilling with rock armour at the offshore end of the 9’ diameter inlet culvert
- Installing a substantial grout plug to the shore side of the inlet culvert
- Installing a substantial grout plug to the outfall culvert
- Infill and reconstruction of the outfall revetment to match the existing sea wall
The scale of the works was considerable, with material quantities including approximately 1,300m³ of armour stone, 300m² of dressed stone to match the sea wall, and 170m³ of high-grade underwater concrete. The plant requirements were also substantial: marine plant included a 32m spud-leg barge, a 25m multicat and a safety boat, while shore-based plant included grout pumps and a 25m long-reach excavator.
During methodology planning, specific consideration had to be given to the challenging location. The inlet culvert was permanently submerged under more than 10m of tidal seawater. The offshore inlet tower was located in an exposed area of the North Sea, while the outfall was situated within the tidal/splash zone of the shore, an area well known for bad weather and rough seas, and also within several nature conservation areas. The project also faced delays due to nesting cormorants.
The first stage was to block and isolate the shore-side inlet, creating a concrete plug in the culvert leading to the power station. Using steel formwork with reinforcing bar drilled into the culvert, a plug approximately 15m long was formed, successfully isolating the decommissioned station from the North Sea.
To remove the intake structure, the steel framework was cut down, winched, and lifted off using a crane on a jack-up barge. This left six piles to be cut off at the seabed. These were removed using a hydraulic diamond wire cutter, with each 450mm-diameter, reinforced concrete-filled pile taking up to 40 minutes to cut through.
Take a look at the video below to see the EDS team in action:
