Phase 1 Contamination Risk Assessment — Residential Conversion Adjacent to Former Works, Chertsey
We prepared a Phase 1 PRA for 2a Guildford Road, Chertsey — a more complex contamination profile than its neighbour, with the site overlying a Principal superficial aquifer in SPZ Zone 2 and multiple off-site contamination sources within close proximity.
Phase 1 Contamination Risk Assessment — Residential Conversion on Principal Aquifer, Chertsey
Location: 2a Guildford Road, Chertsey, KT16 9BJ, Runnymede Borough Council | Client: Arkidraft Ltd | Services: Phase 1 Preliminary Risk Assessment
A Denser Cluster of Contamination Sources Than the Neighbouring Plot
Just metres from 2 Guildford Road, the contamination profile at 2a presented a notably more complex picture. The site overlies a Principal superficial aquifer — river terrace gravels with high hydraulic connectivity — and sits within Source Protection Zone 2. Multiple off-site sources were identified: a historic gasworks complex 51–100m SE, an off-site oil tank at 29m east (1915), unspecified works at 3m SE (1973–1982), and Tank or Trough features at 5–7m NE (circa 1870).
We were appointed by Arkidraft Ltd to prepare the Phase 1 PRA following LCRM (2025) methodology. The Groundsure Enviro+Geo Insight report (ref GS-MTS-4T1-7XF-56H, April 2026) documented the source configuration. All leaching and migration linkages carried Severe consequence due to SPZ Zone 2 and high-vulnerability Principal aquifer.
Despite the complex source environment, overall risk was classified as low — no confirmed industrial use on the plot, no below-ground works proposed.
Outcome
The Phase 1 PRA gave Runnymede Borough Council the basis to support the application while documenting the hydrogeological sensitivity for future reference.