Project overview
Anglian Water Services wanted to reduce the number of combined sewer overflow (CSO) spills. This project focused on identifying which Combined Sewer Overflow (CSO) catchments could benefit from green infrastructure solutions – such as Sustainable Drainage Systems (SuDS) – to help reduce the number of CSO spills. Each catchment was assessed to see where SuDS could be placed near viable surface water sources.
Project goals
- Assessing SuDS potential
To find out which catchments had the space and conditions to support large-scale SuDS that could divert significant volumes of surface water and reduce pressure on the sewer system - Targeting the right sources
To focus on areas where surface water enters the system and place SuDS nearby for maximum impact - Using data to guide decisions
To build a clear picture using multiple data sets, helping the team make informed decisions through a Red-Amber-Green (RAG) scoring system
Key project stats
Our role
Binnies played a key role in helping to identify and assess opportunities for sustainable drainage systems (SuDS) across different catchment areas. The work included:
- Collecting data
Gathering and organising the right data to support the analysis and placement of SuDS options - Understanding the network
Mapping out the client’s drainage areas (ATO polygons) and how they affect Combined Sewer Overflows (CSOs). This included identifying where surface water joins the combined network and calculating volumes from the network and large roofs - Placing SuDS options – Using mapping data to find suitable locations for SuDS within each CSO catchment
- GIS mapping and analysis – Analysing how potential SuDS features relate to key layers (like land use or infrastructure) using GIS tools, based on set rules
- RAG assessment – Creating a Red-Amber-Green (RAG) scoring system to rank SuDS options. This included calculating how much water each option could manage
- Delivering results – Producing clear outputs including
- Maps showing SuDS options by RAG score
- GIS files with all relevant data
- Spreadsheets listing the options
- A report summarising the findings for each catchment
- Client engagement – Holding regular meetings with the client to share progress and updates. Continuous learning and adaptation led to faster delivery in later phases, improving overall project efficiency
- Defining an adaptive methodology: The project required a new approach for SuDS placement and RAG scoring, with a developing definition
- Multiple stakeholders increased the risk of conflicting or changing instructions, affecting time, cost, and quality
- Some datasets were missing or incomplete, which could affect the quality of the RAG assessment
- Interdisciplinary Communication – working across multiple teams and disciplines required careful management of data formats and approaches
- Binnies held early meetings with the client to agree on the scope and method. They also prepared internally to speed up alignment and reduce delays
- Binnies requested a smaller, consistent client-side team for meetings and kept a change log to manage updates
- Binnies adapted the RAG methodology to account for missing data and flagged gaps early to the client, allowing for timely adjustments
- Binnies ensured clear, tailored communication between disciplines and requested written summaries to support shared understanding
Anglian Water Services – SuDs
Anglian Water Services mapping
Anglian Water Services – SuDS chart