In February 2021, our team was commissioned to attend a site visit with NR Asset Team to an embankment showing signs of movement where a 20mph ESR was in place.
Armathwaite
The 50m long embankment is ~8.5m in height, with a 33-34° gradient and is located on sidelong ground with a 600mm stone culvert running beneath. The failure was identified at the toe of the slope of the Upside, with the anticipated root cause expected to be a culvert blockage, leading to water infiltrating through the embankment from the Downside.
Our project philosophy included working collaboratively with the NR team to fully understand their aspiration and expected outcomes. Fairhurst and QTS jointly developed a design solution focusing on mitigating the root cause of the failure, and adopting a risk based, betterment approach rather than strict compliance to current design standards for the remedial works. This Minimum Viable Solution strategy was optimised as an embankment regrade within NR property, supplemented with drainage works and mitigation measures against culvert blockage on the Downside to future proof the asset against similar adverse conditions.
Throughout the works, Fairhurst engineers carried out site reviews to validate any design assumptions and enhance our engineering assurance in addition to our ITPs. Although our site team faced all types of weather conditions including Storm Arwen and Storm Barra, all works were completed as planned without any safety incident with over 2,500 safe working hours.
