DfI - 6011577 - Milewater – New Flap Valves To Existing Culverts

Tender description

The proposed works involve the retrofit of the existing twin 2.0m diameter concrete circular culverts with 2 no. flap valves, to be installed within the existing manhole structure. These modifications are intended to mitigate tidal backflow. To facilitate safe and routine access for maintenance and inspection, the existing manhole is to be altered to allow for man entry. This will require an increase in the manhole’s footprint to accommodate safe working space and access provisions. The existing manhole measures approximately 3.7m in width, 2.3m in length, and 2.98m in depth at its deepest point. The cover slab shall be redesigned to enable future removal and replacement of the flap valves with minimal disruption. This includes the incorporation of appropriate lifting and access features. Given the tidal nature of the manhole, the design and implementation of temporary works must address water ingress and ensure a safe, dry working environment throughout the construction period.