150-year-old waterworks to get €200m upgrade
A 150-year old tunnel considered at risk of collapsing and which supplies water to more than 300,000 customers will be replaced as part of an upgrade of one of the country's oldest drinking water treatment plants.
Irish Water has sought permission for a €200m upgrade of the Vartry Waterworks in Wicklow, which includes the replacement of the 4km Callow Hill tunnel which supplies water to north Wicklow and Dublin.
The scheme was built in the 1860s across a 22 hectare site and was designed to reduce the risk of cholera, typhus and other diseases associated with contaminated water.
It currently supplies 15pc of the Greater Dublin Area's supply, or some 80 million litres a day.
But the supply has been identified by the Environmental Protection Agency (EPA) as being at risk of failure, with Dublin City Council warning in 2011 that the Callow Hill tunnel could suffer a "partial or total collapse" at any moment. This would result in "significant supply problems for an extended time", it added.
The works include:
- Construction of a new water treatment plant on the site.
- A new 4km pipeline and pumping station to transfer water from the site to Callow Hill. The existing Callow Hill tunnel will be decommissioned, but may return to use at a future date.
- Replacing ageing pipes and fittings within the dam at the Vartry reservoir.
- Improvements to a spillway to allow for more water to be diverted away from the dam, reducing the risk of collapse.
If approved, the project should be completed by 2019 or early 2020.
The upgrade is linked with proposed works at the Stillorgan Reservoir in south Dublin, which is being developed separately.
The Vartry scheme includes two storage reservoirs capable of holding 17 billion litres of water. A slow sand filtration treatment plant, where water is drained through layers of sand and rock before chlorine and lime is added to disinfect the water, is also being upgraded as it is leaking.
A planning report notes that "urgent investment" is required. This is because the scheme is also at risk from algae blooms between March and May which can reduce output by as much as 50pc.
The tallest structure will be a sludge treatment building at 12.5 metres. Much of the existing equipment, which is still used today, will be removed but kept as museum pieces.