Lee Valley Reservoirs Upstream Servicing
location
Lee Valley, London
The Challenge
The primary challenge was to restore the integrity of ageing dam faces while ensuring water quality remained unaffected. The site’s scale and operational importance demanded meticulous planning and sequencing to maintain supply continuity for London’s residents.
As the reservoirs remained in service throughout the works, all materials and methods had to meet rigorous water safety standards set by Thames Water, including detailed testing and verification of asphalt components.
The Solution
HEP carried out upgrades on four of the Lee Valley Reservoirs, applying approximately 9,000m² of Open Stone Asphalt (OSA) in a 125mm-thick layer with a reinforced toe detail. The OSA provided a robust and impermeable surface, improving durability and reducing future maintenance requirements.
Prior to installation, Thames Water conducted comprehensive water quality tests on the OSA to confirm its suitability. Testing after completion verified that all results met required standards, ensuring ongoing safety and compliance.
How We Delivered
The 12-week programme was delivered with precision and efficiency, ensuring minimal impact on reservoir operations. Works were sequenced to allow continuous site access, and materials were delivered and placed under strict quality control.
By leveraging proven methods and close collaboration with the client, the project achieved a shorter programme and lower cost compared to traditional resurfacing techniques, while delivering a durable long-term outcome.
Community & Environment
As a critical component of London’s drinking water infrastructure, environmental protection was paramount. All operations were carefully managed to prevent contamination and preserve water integrity. The project demonstrated how essential maintenance can be carried out safely within operational reservoirs while maintaining high environmental standards.
Community impact was minimal, with works planned around operational needs and completed without disruption to the public water supply.
The Outcome
The Lee Valley Reservoirs project successfully restored the upstream faces of four reservoirs, extending their service life and improving resilience against future weathering. The use of Open Stone Asphalt provided a cost-effective, long-lasting surface that met the client’s stringent water quality and performance requirements.
Delivered on time and within budget, the project ensured that London’s drinking water infrastructure continues to operate reliably, maintaining safety, efficiency, and long-term value.
