If you’ve worked in ground engineering or development for any length of time, you’ll be familiar with the phased approach to site investigation. It’s one of the most well-established principles in geotechnical practice: build knowledge progressively, let each stage inform the next, and don’t commission intrusive investigation until you understand what you’re looking for.
GeoScreen’s tiered structure isn’t a pricing model dressed up as a methodology. It’s a direct expression of how ground risk assessment should work — and how, in an ideal world, it always would.
What the industry guidance says
The Code of Practice for Site Investigations (BS 5930:2015+A1:2020) is the definitive UK standard for how ground investigation should be planned and executed. At its core is a principle that often gets lost in the commercial pressures of development: site investigation should be proportionate to the complexity and risk profile of the site, and it should proceed in stages.
Eurocode 7 — the European standard for geotechnical design, adopted in the UK as BS EN 1997 — reinforces this with particular clarity. EC7 Part 2 (Ground Investigation and Testing) explicitly requires the collection and review of existing ground information as the first step in any geotechnical design process.
Before a borehole is sunk or a trial pit excavated, EC7 expects a desk study. This isn’t optional guidance — it’s a design requirement built into the standard that underpins foundation design, retaining wall design, and slope stability assessment across the UK and Europe.
EC7 also introduces Geotechnical Categories — a framework for calibrating investigation effort to the complexity and risk of the structure being designed:
Geotechnical Category 1 (GC1): Small, simple structures in well-understood ground conditions. Minimal investigation required — qualitative assessment and experience-based methods are appropriate.
Geotechnical Category 2 (GC2): Conventional structures and foundations where the ground conditions are not exceptional. Quantitative geotechnical data and investigation are required, but routine methods apply.
Geotechnical Category 3 (GC3): Large or unusual structures, highly variable ground, or sites where the consequences of failure are severe. Extensive investigation, specialist analysis, and high levels of professional oversight are required.
The Geotechnical Category framework is the formal statement that proportionality matters. The Site Investigation in Construction guidance published by the Institution of Civil Engineers, the AGS guidance on desk study scope, and the National Planning Policy Framework all point in the same direction: proportionate, staged, progressive ground risk assessment — starting with the desk study.
It’s worth being clear on one point here: assigning the Geotechnical Category for a project is a professional judgement that rests with a chartered geotechnical engineer, made in the context of the proposed structure and the ground conditions. No screening tool — GeoScreen included — determines the category on its own. What an early-stage assessment can do is surface the ground risk indicators that inform that decision.
EC7 also requires the development of a ground model: a progressively refined representation of the ground conditions at a site, built up from the desk study through to the final investigation. The ground model isn’t a deliverable at the end of the process — it starts at Stage 1 and is updated at every subsequent stage. The desk study is where the first version of that model is formed.
Where practice diverges from principle
In reality, the phased approach breaks down — particularly at the start of the process. The desk-based assessment — Stage 1, the foundation of the EC7 ground model — is the stage most routinely skipped, compressed, or performed at inadequate quality on small and medium-sized development projects. Not because developers or consultants don’t know it matters, but because of the economics. A properly executed desk study requires time and professional resource. At early feasibility, that cost is difficult to justify — even though the information it produces is arguably more valuable at that stage than at any other.
How GeoScreen’s tier structure reflects phased practice
GeoScreen’s four tiers map directly onto this professional framework — and onto EC7’s Geotechnical Category structure:
Tier 0 — Ground Risk Snapshot (£75 + VAT): The first filter. Rapid RAG-rated assessment of eleven geohazards in under 30 seconds. It surfaces the ground risk indicators that help establish whether GC1, GC2, or GC3 conditions might apply — though the category itself is a professional judgement for a chartered geotechnical engineer to confirm.
Tier 1 — Automated Ground Risk Report (£150 + VAT): The structured desk-based screening assessment. Eleven geohazards, fifteen map figures, complete narrative. For many sites exhibiting GC1 characteristics, a Tier 1 report provides the early-stage ground risk intelligence needed to inform feasibility — and, in every case, recommends that a professional desk study is undertaken before the project advances. The proportionality principle is clear: a structured, automated screening report is the right tool to establish the preliminary risk picture, not a substitute for the professional assessment that follows.
Tier 2 — Engineer-Reviewed Report (in development): As a project moves beyond initial feasibility — into optioneering, preliminary design, or where elevated risk has begun to point towards GC2 characteristics — both the data and the scrutiny need to step up. By this stage the site boundaries are typically established or being firmed up, and the site is squarely emerging as the preferred option, so the assessment can focus on the ground that actually matters for the next stages of design. Tier 2 draws on higher-resolution, licensed datasets — BGS 1:50,000 geology among them — to inform the assessment more precisely than the regional-scale data appropriate at screening stage. A Chartered Geotechnical Engineer then reviews the data, findings and conclusions, applies professional judgement to refine the preliminary ground model, and adds the further detail and contextual understanding the next stage of decision-making depends on. At this point it is a professional report — albeit one where the platform and AI handle the data capture and much of the heavy lifting, leaving the engineer to do what only an engineer can.
Tier 3 — Professional Desk Study (delivered by Magnum GSI Ltd, or by any qualified geotechnical consultant): The full BS 5930:2015+A1:2020 and EC7-compliant professional desk study. With the site boundaries confirmed and the project advancing into preliminary or detailed design — or where the site is genuinely complex, GC2 or GC3 conditions apply, a major planning application is being prepared, or lender due diligence requires it — Tier 3 delivers a formally documented ground model as the basis for the investigation scope and design work that follow.
It contains everything a Tier 2 report does, and goes further: where the project demands it, Tier 3 incorporates bespoke, project-specific geotechnical assessment — trenching assessment for a cable route, deep foundation assessment for heavy structures such as a power station, or settlement assessment for structures sensitive to movement, such as large glazed buildings or utility structures. It is the deliverable the later stages of a project are built on — not merely a response to elevated risk.
One important clarification
The tier structure is a framework, not a prescription. If you arrive at GeoScreen already knowing that your site needs a full professional desk study — because planning has required it, because your lender has specified it, or because previous experience with the site demands it — there is no requirement to start at Tier 0 or Tier 1. You go straight to Tier 3. The tiers exist to provide proportionate options at each stage of a project, not to force a sequence.
The complete phased picture
GeoScreen is deliberately designed so that each tier informs the decision about how to proceed to the next. A Tier 0 snapshot might confirm that a site is clearly unsuitable — saving the cost of a Tier 1 report. A Tier 1 report establishes the preliminary ground risk picture and, in every case, recommends that a professional desk study is carried out before any design, planning, construction or investment decisions are made: it is a screening tool that prioritises and informs, not a replacement for the desk study itself. A Tier 2 or Tier 3 desk study then defines the scope and rationale for any intrusive investigation that follows, meeting EC7’s requirement for a ground model before intrusive works begin.
Eurocode 7 has required this approach for decades. BS 5930 has codified it for longer still. GeoScreen is the first platform to make Stage 1 of that process accessible, affordable, and instant for any site in England.
Tristan Morgan BSc(Hons) EurGeol CGeol FGS AMICE is a UK Registered Ground Engineering Specialist and Director of Magnum GSI Ltd. GeoScreen™ is an automated geotechnical ground risk screening platform available at geoscreen.uk.
