Introduction to the UK Environment Act 2021
The Environment Act 21 became law in the UK in November 2021 and sets out ambitious targets for the protection of our rivers, estuaries, and coastal zones. Part 5 Section 82 requires water utilities to continuously monitoring water quality upstream and downstream of all storm overflow and sewage disposal works, which discharge into a water course.
Water quality monitoring requires the measurement of Dissolved Oxygen, Temperature, pH, Turbidity, Ammonia, and anything else specified in regulations made by the Secretary of State. With 20,000+ Combined Sewer Overflows, plus over 7,000 sewage treatment works in England & Wales, this Act creates a significant challenge to the industry in terms of installation, monitoring and continuous maintenance.
Current state
Combined Sewer Overflows (CSO) are designed to collect both wastewater and stormwater through a single pipe, carrying the combined flow to a treatment plant. Combined sewers are equipped with a relief flow route, so that during surge events pipes and treatment plants are not overwhelmed, resulting in potential flooding of homes and commercial premises. To better understand the impact of these discharges, the Environment Agency introduced a programme requiring water companies to install monitors on the vast majority of storm overflows.
At the end of 2022, 90%+ of all storm overflows were fitted with Event Duration Monitors (EDM), which are a consistent way of monitoring the frequency and duration of discharges. Over 12,000 EDMs have been installed in England & Wales providing data to the Environment Agency as part of the Water Industry National Environment Programme (WINEP). Although this data is valuable in understanding which sites overflow, they cannot measure the water quality impact on the receiving waters.
Challenges of large-scale water quality monitoring programmes
When putting together a large-scale monitoring programme, it is typical to focus on which sites to monitor, what parameters need to be measured, the required accuracy, preferred suppliers with a proven track record, and price. Whilst these are important factors, they do not represent some of the major risks and costs required to run a successful monitoring programme.