AQW 25177/17-22

Mr John Blair
Alliance Party
South Antrim

Tabled Date: 03/11/2021
Answered On Date: 18/11/2021
Priority Written: No

Question:
To ask the Minister for Infrastructure what recent steps her Department has taken to help ensure untreated sewage is not discharged into rivers in South Antrim.

Answer:

It is important to understand that sewer networks have a finite capacity and are designed to overflow during periods of heavy rainfall, to relieve pressure on the sewerage system from safety valves known as Combined Sewer Overflows (CSOs) and Emergency Overflows (EOs) which discharge into the receiving watercourses or the marine environment. The CSOs/EOs are designed to prevent the internal flooding of households and businesses with sewage, which would present a risk to public health.

When CSOs/EOs operate on a sewer network, it is in a storm/wet weather situation (unless there is a sewer blockage) and there will be significant dilution in the receiving environment, which minimises the risks to the environment. When sewer networks are at or nearing capacity, CSOs spill more frequently than designed, and are designated as Unsatisfactory Intermittent Discharges (UIDs). There is currently no effective alternative to overflows, however my Department is engaging with developers and local councils, to promote the use of sustainable drainage systems, which are natural features that help to reduce the flows of rainwater entering the sewers. This reduces the pressure on the sewer network and the risk of spills of untreated sewage.

Within the PC21 Price Control period (2021-2027), NI Water has identified an investment programme of almost £300m to address 136 UIDs across Northern Ireland, alongside investment in sewerage improvements within a number of catchments including £7.5m of investment in the South Antrim area. During the PC21 period, NI Water will also continue its programme of drainage area plan modelling, which will include areas within the South Antrim constituency. These models will provide evidence of the predicted CSO/EO spills/discharges in each area and will inform the development of a suite of solutions to address pollution and to reduce the risk of out of sewer flooding. The implementation of these proposed solutions will be subject to prioritisation with the Northern Ireland Environment Agency and the availability

of adequate funding, and is likely to be during the latter stages of PC21 or within the PC27 (2027-2033) Price Control period.

Water and sewerage infrastructure is highly dependent on the amount of funding made available to NI Water for investment and has been impacted by sustained underinvestment. In total, an estimated £2.1bn is needed during the course of the current 6 year PC21 period, to finance capital investment in water and wastewater. This figure includes approximately £500m for the Living With Water Programme, with further spend on that programme also needed in PC27 (2027-2033) and a similar level of investment is required for future Price Controls.