The company was sentenced at South Tyneside Magistrates’ Court this week after admitting one charge of causing a discharge of untreated sewage into Smithy Burn at Broomley on 19th August 2016.
Two other similar offences were taken into consideration as part of this case following unpermitted discharges of sewage effluent on 26th June 2015 at both Summerhouse and Killerby sewage treatment works, near Darlington.
The pollution at Broomley originated from a storm overflow channel. These allow rainwater and sewage effluent to bypass a sewage treatment works in times of heavy rainfall, to avoid the works’ capacity being exceeded.
By law, storm overflows are supposed to be incorporated into the works’ environmental permit. According to the Environment Agency, this was not the case at Broomley, since Northumbrian Water’s environmental permit clearly states that discharges to Smithy Burn should consist only of treated sewage effluent.
The court heard that Environment Agency investigations found a build-up of silt had prevented flow from reaching the works, and instead diverted it to the storm overflow. Northumbrian Water’s maintenance inspections hadn’t included a requirement to check a manhole chamber where the blockage would likely have been discovered.
Samples taken from the burn revealed a thick sewage fungus affecting the watercourse for 100 metres downstream of the outfall, which had starved the water of oxygen, killing freshwater shrimp and midge larvae.
The Environment Agency found that the sewage works were in a poor state of repair, with faulty equipment. Rather than discharging treated sewage effluent, sampling at Killerby showed effluent leaving the works was more polluted than where it arrived.
Northumbrian Water’s barrister told the court that employees were to blame for the faults, not the company, as they hadn’t followed the company’s inspection procedures. He also maintained that the storm overflow at Broomley had been permitted because it was included in the permit application made in 1989.
In sentencing, District Judge Roger Elsey ruled that the company’s culpability was low but that the additional offences meant the fine had to be increased.
Environment Agency area environment manager Fiona Morris said: “The incident at Broomley had a significant impact on the ecology of Smithy Burn. This case demonstrates how important it is that water companies and wider regulated industries understand and comply with the conditions by which they are permitted to operate.”