Five long term steps to delivering Defra's Storm Overflow Reduction Plan

The challenge has been set for us as an industry to significantly reduce spills occurring to the environment from combined sewer overflows. The guidance is driving action but is it driving the right behaviours to create the best outcomes?

05 Oct 2022

Initial responses to set interim targets year by year to knock overflows off the high spillers list one by one could run the risk of downplaying the magnitude of the task ahead or force decision making before data required to make decisions is ready and available.

The vast number of factors to consider means developing an optimised plan that ticks all the boxes and accounts for future flows, network / process interactions, balance between hydraulic and operational cause, capacity in the network, source of flows into the network, status of the discharge waterbody, priority of overflow in the plan, opportunities for quick wins, land use and natural drainage patterns of the catchment, linked flooding locations, amongst other factors, is complex.

This complexity is a call for teamwork and collaborative working, a call to get our data in order and a call to use the data effectively and efficiently to plan and implement sustainable solutions across our wastewater networks.

Collaboration and Teamwork

If ever there was a time to use all skillsets and bring them together in teams then the time is now. The traditional barriers we face to achieve collaboration (individual personalities, funding, profit, competition etc) need to be broken down and worked around to allow people to fulfil their potential and play their part in achieving the long-term plan. From emerging talent to experienced engineers, planners, modellers, programmers or managers, there’s a part for all to play in achieving a sustainable wastewater system for future generations.  

Decision Support Tools – Analytics and Optimisation

Data availability for decision making is increasing at an exponential rate, and it seems like individuals across the board are finding great ways to cut and splice the data to fit their purpose and achieve their objectives, but we need shared data platforms, so all members of the wider team are on the same page now and moving forwards as we embrace the use of ‘live’ performance data-streams. Access to the characteristics and performance of assets, of wastewater networks and WwTW’s and also river catchments. The right decision support tools would mean informed decision making creating a move from the back foot to the front foot for drainage planning.

Workers accessing defence data systems using computers

Thinking and Acting with a Sustainable Mindset

There is resistance to doing things differently as we don’t know what the outcomes or costs will be. There’s been a huge focus on making solutions cost beneficial, but generally sustainable solutions, even with the added benefit value do not compare with traditional solutions for achieving performance targets. As an industry we need to gather more evidence on what works and what doesn’t, we need to characterise the catchments and problems and identify what suite of options would be suitable for a given set of catchment constraints.

Catchment Controllers

Sustainable drainage and green infrastructure needs to be part of a wider plan in a given area, providing recreational areas, space for nature, cleaner rivers, carbon reduction. So what if any construction had to be approved by a catchment controller committee whose purpose was to drive a sustainable future, only approving infrastructure that will provide an overall positive effect on the environment? Would this be enough to drive an approach that characterises and resolves the root cause of the spills into the river rather than finding solutions overflow by overflow?

Adaptive Pathway Approach

Drainage and Wastewater Management Plans (DWMPs) have introduced the concept of adaptive planning into Wastewater Planning, but there’s still a long way to go until adaptive pathways can be implemented and followed successfully. Reliable decision support tools supplying recent (or live) data need to be available to make decisions, follow along a path, understand the consequences of following that path and allow you to change and follow another path that is right at any given time.

There is a sizable challenge ahead over the next 30 years, but by setting out with these points in mind, and a clear strategy on how we make them happen, it’s a challenge we will all rise to.

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