Sheep Bridge

Working in a live river environment demanded solutions for working in unstable riverbed conditions whilst managing water flow, with a Porter Dam requiring twice-daily checks to prevent failures caused by river force, which on one occasion tore a large hole requiring immediate repair.

Strict environmental constraints were necessary to protect the river ecosystem, particularly fish populations and to prevent the spread of invasive species. Communication difficulties in the remote location with no mobile phone signal required all communication to be managed via email, complicating coordination and emergency response protocols. Load-bearing considerations involved using a nine-ton excavator on a bridge with a posted 3-ton limit, requiring advance structural surveys and careful management of load distribution. Access limitations beneath the bridge created confined spaces limiting access for concrete pumping equipment, requiring alternative material handling solutions.

McPhillips developed a tailored approach addressing the unique challenges presented by the Sheep Bridge environment.

Comprehensive environmental management recognised the critical importance of protecting the river ecosystem through a fishery permit process with careful removal and relocation of fish using electric stunning techniques, with all fish safely scooped out before work began in the river.

The team rigorously monitored and removed invasive American crayfish, which carry disease harmful to native species, and implemented daily decontamination protocols to prevent cross- site contamination. Phased construction methodology maintained structural stability throughout works through carefully sequenced construction approach, dividing the bridge into four quadrants that could be completed sequentially whilst maintaining structure integrity.

Controlled water management involved Porter Dam installation with 4 tons of sandbags allowing daily water pumping with twice-daily checks to prevent failures, with immediate repairs made at no extra cost when river force tore a large hole.

Specialised material application used high-strength concrete allowing walk-on strength within two hours, crucial for the tight schedule and challenging river environment, with concrete mix specifically selected for performance characteristics in damp conditions.

Adaptable communication protocols implemented daily morning briefings despite lack of phone signal, reviewing tasks, risks and safety to enhance team focus and reduce accident potential whilst ensuring alignment with daily objectives.

Collaborative stakeholder engagement with Balfour Beatty and local suppliers such as SMC Concrete ensured timely concrete delivery and quality control despite communication challenges.

The Sheep Bridge repair project was completed successfully achieving all primary objectives with zero defects and demonstrating effective management of complex civil engineering works in environmentally sensitive settings.

The bridge’s undercutting issues were fully addressed with new scour protection properly installed to prevent future water infiltration beneath the structure, restoring structural integrity. All works were completed in accordance with environmental permits and requirements, protecting the river ecosystem and preventing the spread of invasive species.

Historical aspects of the bridge were maintained through careful replacement of isolated spalled and missing stonework. The project was completed with no safety incidents despite the challenging river environment and heavy machinery requirements.