Kier Infrastructure, Regional Civil Engineering Par St Blazey Flood Alleviation Scheme, for the initiative Biodiversity Net Gain Initiatives

The multimillion-pound St Austell Resilient Regeneration (StARR) project aims to reduce flood risk to over 800 homes and businesses in Par and St. Blazey, Cornwall. Built on a former estuary, the town’s flood defences are old and over the years have become susceptible to the impact of climate change with increased flooding and coastal erosion. Working with its client the Environment Agency, the team at Kier have exceeded expectations beyond their contractual obligation to deliver the flood alleviation scheme, by driving an initiative to create a biodiversity net gain and carbon saving.

Improving the environment and reducing carbon was always at the heart of this scheme and the client allocated additional budget for contractors to investigate environmentally friendly initiatives to enhance the site. Striving to make a difference to the natural ecosystem and local community, the team at Kier grasped this opportunity and in consultation with the public, they proposed plans to transform an uninteresting riverbank into a publicly accessible and wildlife friendly area.

The approved plans included:

  • Installation of thirty species specific bird boxes to encourage birdlife.
  • Reusing felled trees and turning them into cycle storage racks and benches for the local community to use.
  • Creating two hibernacula areas for use by amphibians and reptiles throughout the winter to protect themselves from the cold.
  • Planting lower-level vegetation to provide safe corridors and shade for wildlife.
  • Replacing grass with UK perennial wildflower mixes along the embankments to support bee populations.
  • Introducing bee hotels and bee bricks made from china clay waste to encourage the local bee population.
  • Reinforcing river margins through the introduction of vegetated coir rolls to provide increased flow variation and shading along the river corridor for fish.
  • Replacing proposed gabion baskets with used preseeded Geogrow bags to provide a soft engineered solution to reduce carbon, cost and generate biodiversity benefits.
  • Introducing timber flow deflectors and stepped rocks in place of a concrete weir structure to address fish passage constraints.
  • Installing eel pipes, two kingfisher tunnels and recesses in stonework and slate ledges to provide fish refuges.

The flood alleviation and regeneration scheme has not only helped protect the livelihoods of hundreds of thousands of people living and working in the area, but through the commitment of the team at Kier has transformed the riverbank into a wildlife haven, creating an impressive biodiversity net gain and a new area of public space that will be enjoyed for many years to come.

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