E3P Case Study: Addressing a Unique Emulsified Groundwater Plume at the Former Vita Works

E3P, a SocEnv Employer Champion, were recently recognised by the Environment Analyst’s Brownfield Awards for their incredible work to address a Unique Emulsified Groundwater Plume at the Former Vita Works and the outcomes from that joint project. Learn more about this project below

Case Study: Addressing a Unique Emulsified Groundwater Plume at the Former Vita Works, Seaford Road, Salford

E3P and McAuliffe Group were appointed to assess and remediate the former British Vita Works on Seaford Road, a brownfield site with a long industrial history of manufacturing waterproof fabrics, adhesives, paints, rubber products, and plasticisers. What appeared at first to be a conventional solvent-impacted site soon revealed itself to be one of the most technically challenging remediation projects undertaken in the UK.

During the detailed characterisation, the project team identified a highly unusual contaminant condition: a stable, viscous emulsified plume suspended within the shallow aquifer. This contaminant phase did not behave in accordance with any established model in the Environment Agency’s Remedial Targets Methodology. Instead, decades of mixed chemical releases had combined to form a complex, multi-component emulsion that resisted standard investigation and treatment approaches.

A Rare and Scientifically Complex Contamination Scenario

The site had been affected by historic releases of:

• Chlorinated solvents, including trichloroethylene (TCE) and 1,1,1-trichloroethane
• Petroleum hydrocarbons such as benzene, toluene, ethylbenzene and xylenes
• Phthalate plasticisers, principally dibutyl phthalate (DBP)

Under typical circumstances, these compounds separate into light non-aqueous phase liquids and dense non-aqueous phase liquids with predictable attenuative behaviour.

At Seaford Road, however, interactions between phthalates, aromatics and chlorinated solvents created a stable emulsion within the groundwater. Phthalates acted as co-solvents and surfactants, reducing interfacial tension between immiscible fluids, while degradation processes further altered redox and pH conditions. The result was a highly mobile, chemically reactive and largely unprecedented contaminant mixture, capable of migrating beyond historically assumed boundaries.

This complexity meant that traditional models based on independent contaminant behaviour could not be applied reliably. A bespoke approach to risk assessment, remediation design and verification was therefore required.

Challenges Identified

• Principal aquifer within Sherwood Sandstone directly beneath the site
• Emulsified phthalates increasing the mobility of aromatic hydrocarbons
• Residual DNAPL and LNAPL linked to former storage tank areas
• Heterogeneous permeability in both the unsaturated and saturated zones
• No established UK regulatory precedent for emulsified mixed contaminants

This combination created a technically demanding environment requiring a tailored and science-led remediation strategy.

Strategy Development and Remediation Design

A substantial historic dataset, combined with new targeted investigation, enabled refinement of the conceptual site model. Additional monitoring wells, vertical profiling and groundwater sampling provided baseline conditions and informed site-specific remedial targets.

The remediation strategy was phased as follows:

Phase 1 – Western and Central Areas (Former Tank Farm)

• Excavation of impacted soils from the vadose zone
• Chemical analysis against site-specific remedial thresholds
• Ex situ bioremediation using engineered windrows, with monitoring of moisture, temperature, nutrient levels and gas
• Engineering treatments to enable reuse of validated soils under CL: AIRE DoWCoP
• Rolling validation to maintain programme efficiency and minimise delays to the developer

Phase 2 – South-Eastern Sector (Emulsified Plume Zone)

Given the atypical contaminant behaviour, a multi-stage in situ treatment train was implemented:

• In situ chemical oxidation using Oxygen BioChem, a combination of sodium persulphate and calcium peroxide
• Injection of emulsified zero valent iron and organic carbon substrates to stimulate reductive pathways and longer-term biodegradation
• Direct-push Geoprobe injection to achieve precise distribution within heterogeneous strata
• Pump-and-treat and free-product recovery in areas of accumulated mobile phase
• Enhanced aerobic and anaerobic bioremediation to provide sustained attenuation

Telemetry-enabled injection equipment allowed real-time monitoring of oxidation–reduction potential and oxidant persistence. This ensured accurate dosing, avoided unnecessary consumption of reagents, and improved the overall efficiency of the treatment process.

Innovation and Best Practice

The project incorporated several best-practice and innovative techniques, including:

• First known UK application of in situ chemical oxidation targeting emulsified phthalates
• High-resolution vertical aquifer profiling and tracer-based delineation of DNAPL distribution
• Adaptive reagent dosing guided by real-time telemetry
• Bench-scale trials to calibrate stabilisation techniques for soil reuse
• A rolling remediation front to maximise programme efficiency
• A combined validation toolkit including multi-level sampling, PID screening and laboratory analysis

Each measure contributed to a robust and regulator-approved remediation framework capable of addressing the unique contaminant mixture present at the site.

Outcomes and Environmental Benefits

• More than 95 per cent reduction in contaminant mass flux to groundwater following the treatment programme
• 90 per cent of treated soils reused on site, significantly reducing vehicle movements and associated carbon impact
• All agreed remedial targets achieved or exceeded
• Planning conditions for contaminated land discharged by the Environment Agency
• Long-term monitoring confirmed stable, non-rebounding conditions in both soil and groundwater

The project enabled safe redevelopment of the site for residential use while contributing to the wider objectives of sustainable land reuse and community regeneration.

Conclusion

The Seaford Road project represents an important milestone in UK brownfield remediation. It required an advanced scientific understanding of contaminant chemistry, a flexible and technically robust remediation strategy, and close collaboration between regulators, technical specialists and the developer.

The successful treatment of the emulsified plume provides a valuable reference case for future projects involving complex mixed contaminants, and sets a high standard for innovation, compliance and environmental performance in the remediation sector.

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