Operations & management |
Investing in Craig Goch Dam
Welsh Water has been carrying out essential maintenance work to protect and future-proof Craig Goch Dam
Dw ˆ r Cymru Welsh Water
Above: Excavator breaking out rock down to formation level of the valve chamber that is to be built at the end of the spillway
Below: Excavator using a hydraulic breaker to take the rock within the gorge back far enough to allow the valve chamber to be constructed
CRAIG GOCH DAM STANDS at over 36m in the Elan Valley and is one of six dams split into two valleys (Claerwen and Elan) at the upper end of the River Wye catchment in Mid Wales. Often known as the ‘top dam’, construction on Craig Goch began in July 1887 with the arrival of the railway line at the site. In the case of Craig Goch, the line had the furthest to go and a rocky outcrop had to be blasted and dug through on the route to the site, which is now known as ‘Devil’s Gulch’. Work on this masonry dam was completed in 1904, and it now stands 317m above sea level.
The Elan Valley system, including Craig Goch dam, is owned and operated by Dŵr Cymru Welsh Water. The utility company provides clean drinking water and treats wastewater for over three million people in most of Wales, Herefordshire and parts of Deeside. Welsh Water is unique in the water industry, as it is not-for-profit and owned on behalf of its customers, with profits reinvested for the benefit of the customers it serves. Since 2001, it has been owned by Glas Cymru which was formed in April 2001 for the sole purpose of acquiring and owning Welsh Water. The not-for-profit water company is investing heavily and working hard to ensure top quality services to all the communities it serves, and the company is investing £1.8 billion in its water and sewerage network between 2020 and 2025. Welsh Water manages a portfolio of 140 dams of which 85 are impounding, 10 are non-impounding and 45 are potable water service reservoirs. Of the 85 impounding reservoirs approximately 75% of them are earth embankment dams and the majority are over 100 years old. The dams within Welsh Water’s portfolio have a variety of uses including water supply, river regulation, wildfire fighting, hydroelectric generation and amenity.
The Elan Valley System There are four dams on the River Elan – Craig Goch,
Pen y Garreg, Garreg Ddu and Caban Coch. The River Claerwen has the newest and largest Claerwen dam, followed by Dol y Mynach dam which is a partially constructed cyclopean concrete dam. Claerwen was constructed in the 1950s but designed to have a similar aesthetic of the other Victorian dams that make up the system. The reservoirs have a combined storage of 99,500Ml and a combined catchment of 184km2
,
consisting largely of open moorland between 250m and 650m above sea level. The principal purpose of the reservoirs in the
Elan Valley system is for water supply, and these reservoirs supply up to 364Mld (Megalitres per day) to Birmingham via a 118km aqueduct and a much smaller volume of 5Mld to a small water treatment works that serves the local area. In addition to supplying drinking water, there is a
river regulation requirement where up to 231Mld is released from Caban Coch into the River Wye. This is based on downstream river levels and abstraction requirements. A trial is currently being implemented
14 | May 2023 |
www.waterpowermagazine.com
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