Case study

Dawdon mine water treatment scheme

Dawdon mine water treatment scheme protects a vital source of drinking water and is located in County Durham, England.

Dawdon mine water treatment scheme
Dawdon mine water treatment scheme

The Coal Authority identified a risk from rising mine waters to an aquifer, which provides drinking water each day to an estimated 30,000 people in the area.

Risks and challenges

The aquifer was particularly vulnerable because of the potential for mine water to rise through open mine shafts, or natural fissures and faults in the coal measures, leading to irreversible contamination.

The mine water contains more salt than sea water, which is known as hypersaline, and would significantly diminish the quality of the drinking water if mine water levels had remained uncontrolled.

Dawdon mine water treatment scheme
Dawdon mine water treatment scheme

A unique solution

This project was particularly challenging due to the:

  • quality and quantity of the mine water
  • limited availability of land
  • sensitive location, near a local nature reserve on the Durham Heritage Coast
  • local transport links, that include a rail line crossing and a nearby road
Dawdon mine water treatment scheme
Dawdon mine water treatment scheme

These factors made it impossible to follow our usual practice of constructing passive lagoons and reed beds.

To protect the aquifer a state-of-the-art active chemical treatment plant was constructed. This is housed in a building that has been designed to fit in with the local development. We recycled 89% of the waste generated during the construction of the plant, which was approximately 135 tonnes of material.

Each year the scheme treats approximately 2,200 million litres of mine water.

Dawdon mine water treatment scheme
Dawdon mine water treatment scheme

Renewable technologies

In early 2016, 192 solar photovoltaic panels were installed on the roof of the main building at the Dawdon treatment scheme.

The panels produce 50kw of electricity each hour and this electricity is being used to off-set the costs of pumping the mine water on site.

Solar panels at Dawdon mine water treatment scheme
Solar panels at Dawdon mine water treatment scheme

In 2011, heat exchangers coupled to a domestic heat pump were installed to capture the heat from the mine water.

The heating and hot water are provided to the offices, workshops and crew rooms, which form part of the treatment facility.

These incentives take us a step closer to reaching our vision of a zero cost mine water treatment scheme.

Published 21 June 2018