'Essential' safety works needed at reservoir

Plans for "essential" safety improvement works at a reservoir in the south of the Isle of Man have been submitted after an inspection found a high risk of flooding.

The Department for Environment, Food and Agriculture (Defa) said the proposals for Kionslieu Reservoir in Foxdale were needed after a 2018 report had found it posed a "high risk of failure" which posed a potential "risk to life".

The plans include making changes to the embankment and constructing new pipework, as well as a new spillway to accommodate extreme flood flows.

However, Defa said, due to the likelihood of there being a high unexploded ordnance level at the site, a survey should be undertaken before work begins.

In its planning statement, the department said that during World War Two the reservoir was known to have been used for live firing military exercises, with records indicating that grenades were dropped in the reservoir during one exercise and not retrieved.

The statement said although the risk from unexploded ordnance was low as the works did not include excavation, staff should undertake an appropriate awareness briefing before beginning work.

The reservoir was believed to have been built over 160 years ago in connection with the various mine operations in the area, the department said in its statement.

Although the department had also considered discontinuing the reservoir, in its current form it provided flood mitigation, it said.

Decommissioning the site could also result in the release of contaminants, which were in the reservoir due to its mining history, into the watercourse system.

The department said it had concluded that works were "essential" to ensure the reservoir was maintained in a safe condition, protecting nearby properties from the risk of flooding, and to ensure the "heavily contaminated silts" were kept in the reservoir basin.

The inspection, published in 2018, had concluded that the reservoir in its current condition had an "unacceptably high risk of failure, posing a risk to life in the downstream communities," the statement said.

Subject to approval, it was recommended that the works were completed by May 2028.

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