Fewston Reservoir Spillway Expansion
location
Yorkshire
Type
DAMS & RESERVOIRS
The Challenge
The PMF modelling revealed that extreme weather events could cause significant overflow, threatening the stability of the dam. The risk of erosion to embankment materials posed a direct structural concern.
The challenge was to complete the downstream spillway expansion within a tight two-week window, working in a live water environment while maintaining safety, precision, and environmental compliance.
The Solution
HEP supplied and installed approximately 1,000m² of Open Stone Asphalt (OSA) across both sides of the spillway channel. The design followed the predicted water flow profile, with slope lengths varied to provide full coverage where hydraulic stress was greatest.
Once complete, the OSA surface was covered with topsoil to restore a natural appearance and blend with the surrounding landscape, ensuring the new protection complemented the existing environment.
How We Delivered
The project was delivered efficiently over a two-week programme, using experienced teams familiar with working in sensitive water environments. Works were carefully sequenced to ensure continuous flow management and prevent downstream disruption.
Close coordination with the client and on-site monitoring ensured the OSA placement followed precise design tolerances. The approach provided a durable, low-maintenance protective layer capable of withstanding extreme flood conditions.
Community & Environment
Environmental stewardship was central to the delivery. All materials and methods were selected for minimal impact on water quality and the surrounding ecology. Covering the OSA with topsoil helped maintain the visual character of the reservoir setting while providing added environmental stability.
Community disruption was negligible, with works planned and completed quickly to preserve public access and ensure reservoir operations continued without interruption.
The Outcome
The completed works strengthened the downstream spillway and significantly reduced the risk of erosion during extreme flood events. The use of Open Stone Asphalt provided a robust, long-term solution that enhances dam safety and performance without altering the reservoir’s natural landscape.
Delivered on time and within scope, the project demonstrates how focused, well-engineered interventions can protect historic assets while ensuring continued resilience against future climate pressures.
