Welsh Water to install two 1km pipes beneath River Dee

Two large pipes each measuring one kilometre could be installed beneath the Dee Estuary to ensure water supply to the area can continue.

Welsh Water is planning to put in two new water mains to cross the estuary in a straight line from a field on Dock Road in Connah’s Quay to the Tata Steel site in Shotton.

The proposed scheme would replace existing mains, one made out of steel and one out of glass reinforced plastic (GRP), which currently run underneath it via a 100-year-old tunnel.

The company, which provides drinking water and wastewater services to most of Wales, said the twin pipelines were being installed as any burst to the GRP pipe could currently stop supply to approximately 1,064 properties, including 14 key commercial premises on Deeside Industrial Park and Garden City.

In a letter to Flintshire Council, environmental consultant Robert Davies said: “The steel main is currently isolated and with no other water supply to the area any burst or problems with the GRP main would result in total loss of supply to the area with no alternative methods.

“In addition, there are long-term maintenance challenges associated with the existing supply through the tunnel.

“A new crossing is therefore required to ensure the resilience and continuity of water supply.

“The area to the north of the Dee Estuary is also undergoing regeneration and development, with plans to build new housing estates on the Northern Gateway Scheme, which will increase the future demand for water supply to 11.5 mega liters per day. This further amplifies the importance of the proposed scheme.”

The two mains would be located at least 24m beneath the river bed and would be installed using horizontal drilling techniques.

The plans have been scaled back from a previous proposal submitted in July 2016, which would have seen approximately nine kilometres of pipe installed further upstream.

Welsh Water said it would take all necessary steps to avoid any damage to the environment.

Mr Davies said: “To avoid significant and direct impacts to protected habitats and associated species of the Dee Estuary, it is proposed to install the twin mains by directional drilling, beneath the bed of the watercourse, over a distance of approximately 175m either side of the channel.

“This would therefore avoid direct impacts on the designated sites listed.
“Natural Resources Wales agreed that the main construction areas would be sited far enough away from the designated sites and associated saltmarsh and mudflat habitat that further bird surveys would not be needed, and the main works would be unlikely to cause a visual or noise impact on birds using the designated sites.”

He said the proposed works were unlikely to affect otters due to the distance from the water, but added that the company would carry out pre-construction checks to ensure they weren’t impacted.

By Liam Randall – Local Democracy Reporter.