Reducing flood risk to communities in the St Austell Bay area

The River Par Flood Alleviation scheme aims to reduce flood risk to more than 800 homes and businesses in Par and St Blazey. The scheme includes engineering flood defence assets along the Treffry Canal and repairing assets located along the Treffry Canal and the River Par. The engineering measures will be supported by softer, natural flood-management solutions aimed at slowing the flows and increasing the storage capacity upstream, which will prevent flooding incidents in Par and St Blazey.

Overcoming obstacles

The work had significant constraints. Owing to very limited footpath access, all materials had to be brought in by foot before installation could begin. Because of the fish-spawning season, all in-channel work had to be completed by the end of September. Despite these significant challenges, we were able to complete our work on programme and to a high quality by operating the two sites concurrently with more than 10 ecological contracting specialists.

RSK Habitat Management mobilised within one week and completed all in-channel work within eight weeks to deliver the programme and protect the fish. Through the application of our innovative working methods, we installed silt-protection measures downstream of the work and dissolved oxygen monitors to manage and monitor oxygen levels. Our teams worked smoothly to complete pre-commencement ecological clerk-of-works duties and bat surveys of potential bat-roost features. Using bespoke machinery, we crown-lifted trees to facilitate site work and create access points, stabilised riverbanks and infilled scour pools using chestnut posts and brushwood faggots, then backfilled and capped with pre-planted coir rolls for a natural engineering solution. In total, we supplied and installed almost 2 km of erosion protection and stabilisation measures. By collaborating with our sister company Salix, we completed all the in-channel work by the required deadline, thus protecting residents in advance of the winter floods.