The treatment plant at Sandown is the only plant branded as a high level of concern by Southern Water in its baseline risk and vulnerability assessment. The water company, however, say those problems could be fixed if surface water run-off was dealt with differently, enabling it to eliminate water discharges into the Solent.
Answering questions from the Isle of Wight Council’s corporate scrutiny committee on Tuesday, Southern Water’s area manager Keith Herbert gave an overview of its position after recent flooding devastated properties across the Island.
Hydraulic overload of the public sewers — or too much water in the system — was found to be a ‘not so hypothetical scenario’, said Mr Herbert. He said the flooding that occurred was a problem shared among agencies, including the Isle of Wight Council and the Environmental Agency.
Mr Herbert said the current system was not the way water should be managed and agencies should be thinking about what should be done instead.
Councillor Peter Spink highlighted the 6 very significant concerns at the Sandown treatment works, which he said was considered to be the Island’s flagship plant, and has a forecasted growth increase of 25% by 2050. The 6 serious concerns were risks of pollution, sewer collapse and flooding, storm overflow, dry weather flow compliance and nutrient neutrality.
Mr Herbert said as part of its £50million plans for the Island in the next 40 years, £9million would be used to address some of those concerns as ‘proactive intervention’. He said:
“A lot of those problems would be resolved by removing surface water connections from the public foul sewer.
“If surface water connections were not plumbed into the foul sewer we would not flood as much and we would not discharge. It is fair to say we could eliminate almost all discharges by removing that surface water runoff.”
One recommendation was to completely separate surface and foul water, as surface water could overwhelm the capacity of public foul sewers.
The company is working towards a full rationalisation of water supplies on the Island as 20 works and 30 reservoirs serve the population which Mr Herbert described as too elaborate. He said things could be made a lot more simple.
When questioned about whether new developments and more housing would add to the pressures, Mr Herbert said newer properties were more water-efficient with older housing stock causing more problems.
Meetings between Southern Water, the council’s cabinet and Island MP Bob Seely have looked at ways forward to fix problems.
Councillor Chris Jarman said one of the outcomes was future developments would need to have complete separation of sewage from surface water. He said it made sound environmental sense and was a no brainer, that at the same time they go back and fix the existing infrastructure.
The water company is developing a drainage and wastewater management plan to ensure the sustainability of the infrastructure so customers’ needs are met and the environment protected.