The Hams Hall battery energy storage system (BESS), located in the West Midlands, represents a significant step forward in the UK’s energy infrastructure. At 400 MW/1.4 GWh, the scheme is set to become one of the largest BESS facilities in Europe once energised upon completion – allowing for the placement of more than 1750 MWh of battery storage. As sites are growing larger and more complex, site fire safety requirements are facing more scrutiny than before, and development designers are putting greater consideration into suitable infrastructure to contain contaminated water from fire events.
Wills Bros Group are working in partnership with Energy-Io to deliver the project, which includes critical infrastructure to manage firewater and contaminated water risks. A firewater storage solution was adopted on site from UK-based Aquaspira, incorporating its recently developed pollution containment tank system into the development design. As the BESS sector scales up, Aquaspira’s approach is setting a new standard for how fire safety infrastructure is designed, installed and compliant.
The BESS site at Hams Hall demonstrates the UK’s quick expansion into the energy storage sector, driven by the need to successfully manage the renewable energy the UK is readily turning to. However, with the size of the new developments comes more scrutiny; with a site this large, there is greater potential for a fire event, and the consequences that follow. Regulators, insurers, and planning authorities are responding to this risk by tightening requirements for new BESS developments, and designers and engineers are making compliance an essential consideration for every project.
The primary guidance document for this critical aspect of infrastructure is Ciria C736 - Containment systems for the prevention of pollution: Secondary, tertiary and other measures for industrial and commercial premises. This requires firewater and contaminated water runoff to be captured and contained to avoid polluting the local groundwater with chemicals from the lithium-ion batteries. Traditional storage approaches have historically struggled to meet the relevant standard – BSEN 1610 Sec-tion 13.3 – with confidence. Tanks must also enable complete removal of the contaminated liquid, and the provide the ability for the tank to be completely cleaned prior to recommissioning the drainage system, which is not possible with, for example, Cellular type crate tanks.
The original firewater storage design comprised a system of concrete pipes connected to 3 x 2.4 mØ diameter manholes at each end. This arrangement required a substantial footprint of approximately 9 x 33 m within a very constrained construction area.
In addition to spatial limitations, the proposed design involved a high number of joints across the pipe runs, with six large, interconnected manholes. Achieving a fully watertight system under these conditions presented considerable challenges.
Due to the complexity of the original design and restricted construction space, Wills Bros identified the potential for leakage and programme delays, seeking an alternative solution that could offer improvements in footprint and buildability.
The adopted solution comprised a three-leg tank configuration, interconnected via a precision-engineered flanged manifold. This approach reduced the overall footprint by approximately 30%, enabling installation within the constrained site while maintaining the required storage capacity.
The system incorporated 6 m pipe sections, significantly reducing the total number of joints to just 15 across the entire tank. Each joint presents a point of vulnerability, with a risk of leakage; design simplification was key to improving installation efficiency and minimising potential leakage points.
Quality assurance was highlighted at every stage throughout the process:
- Pipe sections were air tested at the factory prior to delivery.
- Manifold connections and gaskets were tested on site before backfilling commenced.
- Internal joints were professionally over-welded on-site to provide a secondary seal.
This approach formed part of Aquaspira’s Watertight Assurance Process, designed to ensure performance certainty ahead of formal testing. The installation was completed ahead of programme, reflecting the efficiency of the revised design.
During commissioning and prior to the formal test, the tank was filled and monitored over several days, to demonstrate the effectiveness of the system. The system then subsequently passed the formal BSEN 1610 Water Drop Test without issue, confirming its watertight assurance.
The Hams Hall project reflects a broader shift for BESS sites and how the energy sector approaches the challenge of planning and engineering sites to be compliant with environmental regulations. Firewater containment is moving up the list of priority for developers, and Aquaspira’s pollution containment system has demonstrated its capability to meet these demands. Sites must now prove that they are compliant with formal regulations and site developers must look further than traditional, inadequate methods.
Callum Brown, Senior Project Manager at Wills Bros Group, commented: “From initial design proposal, pre-installation planning, installation advice, through to final testing, the Aquaspira team provided great support. With the Watertight Assurance Process we were confident from the outset that the tank system would do the job, and we weren’t disappointed. We won’t hesitate to use the system on future projects.”
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