Agenda and minutes

The Chairman welcomed everyone to the meeting.

The Chairman wished to bring to the attention of the committee a library where documents were stored, including correspondence with Thames Water, the Environment Agency, the Leader of the Council as well as the Secretary of State. The link for this library, which is public and can be accessed at any time is below:

https://buckinghamshire.moderngov.co.uk/ecCatDisplay.aspx?sch=doc&cat=13716

There were none.

The minutes of the meeting held on 28 April 2023 were agreed as a correct record. The Chairman asked Andrew Scott of Thames Water to update the committee on their action points during his update.

It was noted that Sam Kershaw had sent some questions to Thames Water one of which, in particular, he was hoping would be responded to at this meetin. It was a question that arose at the last meeting that EDM UM system monitors spillages from the storm tank and his question was how are other types of pollution incidents identified and recording recorded if not through the EDM?

In particular implications for investment at the Little Marlow site arising from change of CEO and the utility's emerging financial position.

Andrew Scott explained that they monitor on site for water quality and quantity by online monitoring, which is constant and measured parameters such as flow, compensation flows, outfall solids, outfall authority, ammonia, and storm tank levels. Event duration monitors were also used to detect when they were spilling to the environment. He admitted that they did not measure the volume of storm flows, which was not required by their permit but could have a significant environmental impact. Thames Water would need to implement upstream and downstream monitoring for water quality by 2030 as part of the Environment Bill.

Andrew Scott explained about the monitoring methods and performance of a water treatment site. He showed graphs of suspended solids, biochemical oxygen demand and ammonia, which were the main parameters of their consent. He also explained that they used online and offline tests to measure these parameters and that Thames Water had been complying with the limits. He went on to explain how some events, such as blower trips, could affect the ammonia removal. Andew Scott concluded that the site was operating well and that they would have to meet new requirements in the future.

Andrew Scott went on to explain how Thames Water used ferric to remove phosphorus from the water and monitored the flow and the storm tank spills. He reported that they had achieved very good results in terms of phosphorus and iron levels and that they had not had any spills to the environment in 2022 and 2023. He also showed some examples of false triggers from the EDM monitors, which were caused by various factors such as maintenance, cobwebs or animals. He assured the committee that they had CCTV and storm tank depth monitors to verify that there were no actual spills.

Andrew also explained how quality of the water was monitored and the performance of the treatment process. He showed three graphs that displayed the results for suspended solids, biochemical oxygen demand (BYOD) and ammonia. He stated that the plant met the consent limits for all these parameters, except for one occasion when the blowers that provided air to the aeration lane tripped and caused a spike in ammonia. Andrew concluded that the site was operating well and effectively.

There were no reported pollutions in 2022 and 2023. The EDM going out to storm is not necessarily a pollution but a consented discharge. Andrew also explained that one of the key ways of reporting pollutions is by the local stakeholders or the Environment Agency. Reporting incidents was encouraged as they would be investigated and reported back through the Environment Agency (EA). There was a national incident recording database which was available for viewing.

Andrew explained how Thames Water reported and investigated any pollution incidents that occurred when the water quality exceeded the effluent of concern level, which is higher than the consent limit. He stated that the consent limit was a 95% compliance limit which meant that they could have some variations in the water quality  ...  view the full minutes text for item 5.

The Chairman explained there was no update from the EA and would follow up on his action to liaise with the Leader of the Council to encourage their attendance at future meetings.

*Post meeting note: the EA update is attached.

The Action Log was noted.

Friday 22 March 2024 at 11.00am.

Friday 22 March 2025 at 11.00am.