City water source is to be revamped and new bridge constructed

Altnaheglish reservoir.

Altnaheglish reservoir.

  • by Kevin Mullan

The water service aims to build a new bridge across the Glenedra stream and to revamp a fifty year old intake plant which provides Londonderry with drinking water.

NI Water has applied for permission to carry out the works in the Banagher forest south of Dungiven. Documents submitted to the local planning office describe the Glenedra stream as “critical” to the ecology and biodiversity of the wider Roe system downstream.

An upland spate river, the Glenedra joins the Cushcapel water to form the Owenrigh, which along with the Roe, Owenbeg and Derryware Burn, comprises the Roe system.

According to Doran Consulting the intake structure, which was built in 1966, “is in a poor state of repair and in need of refurbishment.” It’s also prone to flooding. whilst a bridge that provided access over the Glenedra has been damaged beyond use.

“Whilst NI Water can access the intake for routine operations no suitable access is available for heavy duty engineering works,” the documents state.

A single concrete slab, which acts as an ‘unofficial’ bridge, was put there by “unknown persons” without the consent of NI Water or the Department of Agriculture and Rural Development (DARD).

Raw water from the Glenedra intake facility supplied the Caugh Hill Wastewater Treatment works, which in turn provides drinking water to Londonderry. Tap destined H2O flows through a mesh screen and the volume is controlled by a weir wall. But this can be problematic when the stream is in spate.

“At times of high flow the screen can be overtopped allowing material and debris to pass into the tank, reducing the water quality that arrives at Caugh Hill WTW,” the documents suggest. The screen and walls are to be heightened to prevent this.

The intake isn’t salmon friendly as fish can’t migrate upstream past it. An ecological assessment by Corvus Consulting says caution will need to be taken not to disturb downstream spawning grounds during construction.

The Banagher Glen generally is also viewed as ecologically important as “one of the largest and least disturbed examples of old sessile oak woods in Northern Ireland.”

The Doran group states: “The works will improve the visual appearance of the structures within the Forest setting.

“Whilst the works has the potential to impact on water quality and the surrounding environment, these impacts can be overcome by including mitigating measures within construction.

“The works will reduce the future impact on the environment by improving the functionality of the facilities, enabling Nl Water to better maintain and manage their assets and monitor environmental issues.”




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