Future Water has reached another significant milestone in the construction of Portsmouth Water’s Havant Thicket Reservoir with the completion of the reservoir’s culvert, and valve tower structures, alongside the success of the culvert backfill works and above-ground embankment works.
Together, these achievements represent a major step forward in the development of the reservoir and the construction of the main embankment.
The culvert is one of the most important components of the reservoir, forming a key part of how water will ultimately move into and out of the system. Over an 18-month construction programme, the civils team delivered the structure using 4,825m³ of concrete and 2,400 tonnes of reinforcement steel, supported by an average workforce of 45 operatives and five managers. The works were completed safely, contributing to an outstanding record of approximately 200,000 working hours without a RIDDOR incident.
With the structure complete, the focus turned to the earthworks operation surrounding it. The successful completion of the culvert backfill has seen engineered clay carefully placed and compacted around the structure, integrating it into the future embankment and preparing this section of the reservoir for the next phase of construction.
The culvert backfill milestone forms part of an exceptional year for the earthworks team. During 2026 alone, more than 814,000m³ of engineered clay has been placed across the project. Since March 2025, that figure has grown to almost 1.5 million m³, representing one of the largest earthworks operations currently underway in the region.
Other achievements this year include:
- Completion of the Ground Improvement Zone.
- Installation of over 1.1km of slurry cut-off wall, extending to depths of up to 14 metres.
- Commencement of instrumentation and monitoring installations within the embankment, including instruments installed up to 30 metres below ground level.
- Progression of wetlands construction and topsoil placement across completed areas.
Beyond the impressive volumes and statistics, these milestones reflect the dedication, expertise and teamwork of the people delivering the project every day. The completion of both the culvert structure and culvert backfill demonstrates the close collaboration between civil engineering and earthworks teams, ensuring critical infrastructure is safely delivered and incorporated into the reservoir embankment.
As construction continues, attention will turn to the next stages of embankment construction, wetlands development and eastern drainage works, bringing Havant Thicket Reservoir another step closer to providing a resilient water resource for future generations.
For everyone involved, the completion of the culvert and its backfill is a milestone worth celebrating and a testament to what can be achieved through teamwork, expertise and safe delivery.