Aghada CCGT Power Plant

Cofferdams

AGL were geotechnical designers for the temporary cofferdam used for the construction of the cooling water intake building at the Aghada Combined Cycle Gas Turbine Power Plant.

• The wall was constructed as a twin wall sheetpile cofferdam supported by steel ties, rock anchors, deadman anchors and two levels of internal props. It was 50 x 20 m in plan area with a 12 m retained wall height at extreme high tide.
• When the excavation was bottomed out the temporary internal props were replaced by apropping slab at base of structure to provide an open excavation. Rock was just below excavation level which only provided shallow penetration for the sheetpiles.
• The complexed staged construction sequence was modelled by finite element analysis using Plaxis 2D.
• The geotechnical design report was prepared to Eurocode 7 for geotechnical design and a Designers Risk Assessment was prepared to comply with health and safety requirements.
• We also designed the excavation dewatering system and provided monitoring services during constructio