Controversial plans to develop a North Cardiff reservoir would be a “natural business choice”, a public inquiry has heard.
The inquiry is the latest stage in a decade-long wrangle over proposals to build 324 homes and a leisure complex on the site of Llanishen reservoir.
Owners Western Power Distribution have already drained the site – which was granted listed status by Cadw in 2009 because of its unique Victorian engineering – and are applying for the go-ahead on development plans.
But they are opposed by Cardiff council and the Reservoir Action Group, who want the reservoir re-filled.
Dr Andrew Hughes, an all reservoirs panel engineer for Atkins plc, first reported on Llanishen in 1994 for Welsh Water, and then again in 2008 in his current role.
He told the inquiry, being presided over by National Assembly planning inspector Richard Poppleton, re-filling the reservoir with rainwater would taken between eight and 10 years and would incur monitoring costs of £280,000.
A faster but more complicated second option – to re-fill the reservoir using water from the Nant Fawr stream – would take about five years and was likely to cost £230,000 to carry out and monitor, Dr Hughes said.
And he told the inquiry – the fifth of its kind – the state of the Llanishen beauty spot was in decline.
“I’m afraid it reflects exactly how the majority of reservoirs, when they are not operational, tend to deteriorate with time. That deterioration is by weather, vandalism and a number of factors.”
Increasing vegetation, vandals throwing stones in to the reservoir basin, smashed cast iron gratings and the use of concrete in maintenance work had contributed to the downfall, Dr Hughes added.
Empty reservoirs are “normally an uneconomic asset” for owners, Dr Hughes said, adding that developing the site was a “natural business choice”.
But Mike Lowe QC, representing Cardiff council, said Dr Hughes’ report indicated that if the reservoir was re-filled and used for sailing and fishing it was “unlikely to require significant maintenance for the next 50 to 60 years”.
Dr Hughes said he could “see no reason” why any major work would need to be undertaken in the period.
Cardiff North Assembly Member Julie Morgan was in the public gallery alongside campaigners and residents to hear the evidence.
The inquiry continues tomorrow at County Hall in Cardiff Bay.
What do you think about the development of the reservoir? Should it go ahead or not? Let us know in the comments below