The project demanded stringent environmental monitoring to minimise impact on the surrounding community. Its proximity to an active railway line required all works to be carried out under a strict asset protection agreement with Network Rail. Additionally, demolition was needed for a redundant building adjoining an operational office and workshop.

Remediation Scope

Cognition’s primary objective was to remediate the site to reduce environmental and human health risks, enabling its transformation into a residential development. The key remediation activities included:

• Demolition
• Bioremediation
• Chemical oxidation
• Stabilisation and solidification
• Installation of a permeable reactive barrier (PRB)
• Installation of a clay cut-off wall
• Removal of residual Non-aqueous Phase Liquids (NAPL)

To remove NAPL effectively, Cognition deployed its proprietary FabEx fabric extraction system, which allowed targeted removal without the need to extract and treat large volumes of groundwater.

In total, 17,000m³ of contaminated soil was successfully remediated to meet residential criteria. The FabEx system reduced NAPL to less than 5mm thickness at the groundwater interface. A protective PRB wall was installed around the site to prevent offsite migration of contaminants.

Community Engagement

All works were completed with minimal disruption to local residents. Cognition maintained an open and proactive engagement process, issuing regular newsletters and hosting site visits for both the Local Authority and the Environment Agency. This transparent approach was commended by regulators, particularly given the site's visibility from surrounding properties.

Concrete Frame Construction

Following the successful remediation phase, Cognition was invited to construct the reinforced concrete-framed structure for the new residential development. This phase included:

• Construction of six concrete frames
• Heights ranging from three to eight storeys
• A basement-level undercroft car park
• Final development to include 119 private residential apartments and a concierge service

Cognition’s prior knowledge of the site enabled design optimisations that delivered both cost and programme benefits. Notable improvements included:

• Raising the basement slab level, eliminating the need to remove over 3,500m³ of hazardous and non-hazardous material
• Reducing floor heights to maintain overall building massing without compromising apartment design
• Revising the basement car park from an in-situ concrete slab to a tarmac road formation
• Introducing perimeter openings for natural ventilation, reducing the extent of gas membrane coverage

These design changes resulted in significant savings and improved efficiency for the client.

Learn More

To explore how Cognition expertly delivered this complex and multi-phase project, visit our case study:https://www.cognitionlandandwater.com/case-studies/Newbury-Gas-Works/