Designing and Building a New Sewage Treatment Plant on a Tidal Island

Overview

In 2021, WCI Consulting Engineers developed the foul drainage strategy for the ten-year renovation of the iconic Burgh Island Hotel. By 2024, we had won the contract to both design and build it. What followed was one of the most logistically complex wastewater projects we have undertaken to date.

The Challenge

The island is accessible only via a tidal sand causeway. The existing drainage field had failed. A public sewer connection was impossible. A marine discharge below mean low water under EA permit was the only viable solution. All materials had to be transported in tide windows, and a World War Two slipway needed to be reinstated to allow a five-metre primary tank to reach its excavation point.

The WCI Solution

WCI selected a WCS HiPAF treatment plant for its suitability to tidal access, seasonal flow variation and environmental footprint. Marine Management Organisation permissions were secured. 160 tonnes of aggregate were assembled on the mainland and transported by dumper and tractor across the causeway. Rock encountered during excavation required a second excavator to be ferried to the island. A duplex pumping station, above-ground treatment plant, split-level concrete slab and 90-metre electrical trench were completed before heavy-duty cast-iron outfall pipe was laid down the cliff face to low tide level.

The Outcome

Burgh Island Hotel has a robust, sustainable wastewater solution that meets rigorous environmental standards and supports the hotel’s long-term development ambitions.

To discuss your project with our Consulting Engineers team, contact WCI today.