Aldenham Reservoir

The project includes the replacement of an existing dam embankment and delivery of a reinforced concrete spillway, stilling basin and weir, along with a replacement pedestrian footbridge and a new public access footpath along the crest of the dam.

Located near Elstree within Aldenham Country Park, Aldenham Reservoir is one of the oldest impounding dams in the country, originally constructed in around 1795 to provide water compensation for mill owners following the development of the Grand Union Canal.

Retained by an earth fill embankment approximately nine metres in height and 480 metres in length, the reservoir has a capacity of around 539,000 cubic metres and is an important local amenity for visitors to the surrounding parkland. While some remedial works have been undertaken previously, further improvements are required to address ongoing concerns regarding the performance of the embankment dam and ensure the long-term structural integrity of the asset, reducing the potential risk of flooding to nearby communities.

Working on the site of the existing reservoir, STRABAG UK is constructing a new dam embankment incorporating an 8-metre-deep slurry wall, butyl liner and rock armour to enhance the structural stability and long-term integrity of the reservoir.

The project will also deliver a new spillway, stilling basin and weir, along with a replacement pedestrian footbridge and a new public access footpath along the crest of the dam.