Geoenvironmental

Before any development begins, A F Howland Associates recommends conducting a phase one desk study and walkover survey. This initial stage is considered best practice for identifying potential contamination and ensuring that issues not directly tied to current site use aren’t overlooked. This includes:

Data review

• Examination of geological and hydrological maps, regulatory records (e.g. local authority, environment agency), historical ordnance survey maps, and anecdotal evidence.
• Identification of potential hazards, including ground instability, landfill activities, and past or current contaminative uses.

Walkover survey

• On-site inspection to confirm present conditions and correlate visible features with documented historical activities.

Preliminary conceptual model

• Compilation of findings into a conceptual framework, using the source-pathway-receptor principle (PPS23) to establish contamination risks.
• Determines whether a phase two intrusive investigation is necessary based on the identified potential for contamination.

If the phase one survey highlights potential contamination, a phase two investigation is carried out. This involves:

• Exploratory holes & sampling: gathering soil and groundwater samples for chemical analysis and monitoring.
• Refined risk assessment: updating the preliminary conceptual model and producing a quantitative risk assessment to confirm the extent and severity of contamination.
• LPA coordination: ensuring the investigation scope and results meet local authority requirements before work commences.

If significant contamination be identified, development can still proceed under a site-specific remediation method statement (subject to LPA approval). Methods may include:

Excavation & replacement
Hard cover installation
Ground gas ingress prevention
Pump & treat solutions for groundwater

Once remediation is complete, validation testing confirms that contamination has been effectively addressed, ensuring the site meets regulatory standards and is safe for construction.