How Embracing Engineering Challenges Unlocked the Reduction in Embedded Carbon at the SSTC3 Soil Nailing Project

Commencing in April 2020 and completing in June 2021, Aarsleff Ground Engineering Ltd (a UK subsidiary of Danish construction company Per Aarsleff A/S) undertook the design and installation of soil nailing reinforcement and structural facing for a near 12m high slope inclined at 70° from horizontal. The near 250m length of reinforced slope enabled the excavation for a new highway into the side of an existing slope situated above the old shipyards on the south bank of the River Wear in Sunderland, England. The scheme was developed as an alternative to the originally specified retaining wall consisting of a combi-sheet pile wall supported by ground anchors. This paper studies the reduction in embedded carbon achieved through the alternative scheme but details the complex design and technical management required to unlock this achievement. The awkward geometry; the unpredictable ground conditions; the coordination between excavation works and soil nailing; the specified design working life of 120 years; relic buried structures; and more; all posed challenges from the outset that could have spelt disaster unless managed correctly. The project was a success, and many learned lessons are discussed herein for the technical management of more sustainable yet risky geotechnical methods. &nbsp