Arbtech’s Charlie Radiven on the need to tread carefully with ground risk

The biggest uncertainty in ground risk, however, lies not in the soil but in interpretation.

Contamination, historic land use, mining legacy and ground stability can all shape viability. But across the UK, two sites with near-identical ground conditions can receive very different planning responses depending on which side of a local authority boundary they fall. This variability is becoming one of the most commercially significant risks in development.

National planning guidance is clear: geo-environmental risk should be assessed using a proportionate, risk-based approach. In theory, this provides consistency; but in practice, interpretation varies widely. Some authorities adopt a pragmatic stance, focusing on material risks and workable mitigation, while others lean towards more conservative positions. This can result in over-scoped and costly investigations, extensive intrusive works, frustrated developers and remediation strategies that go beyond what the site actually warrants – leading to perfectly viable schemes being pushed to the brink.

Treating all sites with identical investigation depth is neither efficient nor aligned with risk-based principles

For developers, this can mean longer pre-commencement phases, higher investigation and remediation costs, greater planning uncertainty, programme delays and pressure on viability, particularly for marginal brownfield sites.

Not every site carries the same level of geo-environmental complexity. Treating all sites with identical investigation depth is neither efficient nor aligned with risk-based principles. A genuinely proportionate approach delivers tangible benefits including targeted investigation strategies, leaner remediation solutions, faster planning approvals, better commercial certainty and lower environmental impact. Over-investigation is rarely discussed, but it has financial, environmental and programme-related consequences.

Late discovery

One of the industry’s most persistent problems is not the presence of ground constraints, but when they are identified. Late discovery of contamination, mine workings or ground instability can introduce major cost and programme shocks at precisely the moment flexibility is most limited, which is when viability takes a hit.

Early geo-environmental input, ideally pre-acquisition or at site option stage, changes the dynamic. It allows developments to identify constraints before financial commitment, make informed land value decisions, influence layout and foundation design, reduce investigation scope through smart risk assessment and avoid nasty surprises during planning.

The solution is not deregulation, but early dialogue and more consistent application of existing guidance. Where developers, consultants and regulators engage constructively at an early stage, outcomes improve across the board: better shared understanding of risk, clearer investigation scopes, faster planning decisions, fewer programme shocks and more sustainable remediation solutions.

It is less about technical disagreement and more about communication and confidence in proportionate assessment.

As development increasingly targets brownfield and more complex urban sites, geo-environmental constraints will only become more central to viability. But the industry challenge is shifting. The question is no longer just ‘what is in the ground?’, but ‘how will that risk be interpreted, managed and conditioned?’

This is an issue of planning, viability and delivery.

What lies beneath a site will always matter. But in today’s environment, how that information is interpreted – and how early it informs decisions – matters just as much. Developers that treat ground risk as an early strategic input rather than a late technical hurdle are far more likely to protect viability and keep schemes moving.

Charlie Radiven is geo-environmental director at UK ecology consultancy Arbtech