Brownfield Redevelopment: Risks, Costs and Best Practices
Developing brownfield land can be one of the most rewarding (and most challenging) routes to delivering new housing, commercial space, or mixed-use regeneration. From unexpected contamination and ground conditions to planning delays and abnormal costs, brownfield sites often come with a list of complications that greenfield projects avoid.
But with the right approach, these sites can unlock huge value.
At Clear Environmental, we specialise in helping developers and investors navigate the complexities of brownfield redevelopment. Whether it’s an old industrial plot in a city centre or a redundant yard on the urban fringe, we provide clear, commercially-focused advice to reduce risk, keep projects moving, and support planning success.
What Is a Brownfield Site?
Brownfield land is defined as previously developed land that is no longer in use. Typically, these sites often have an industrial or commercial legacy, and are now vacant, underutilised, or awaiting redevelopment. They can include:
- Former chemical works and pigment manufacturing sites
- Redundant factories, engineering works, and industrial estates
- Disused petrol stations and vehicle service depots
- Old gasworks and coke production plants
- Disused railway yards, sidings, and engine sheds
- Warehouses, haulage yards, and storage depots
- Historic landfill sites, quarry infills, and spoil heaps
- Military and defence-related manufacturing facilities
- Docklands, riverside yards, and former wharves
- Garages, dry cleaners, and laundrettes with solvent use
Why Brownfield Sites Carry Risk
The main issues developers face on brownfield land include:
- Contamination: Historic use may have left pollutants in soil or groundwater (e.g., fuels, solvents, asbestos, heavy metals)
- Ground gas: Methane, CO₂, or VOC vapours may be present beneath buildings
- Geotechnical constraints: Fill material, variable strata, or soft ground can complicate foundation design and relic foundations and obstructions can require removal before development
- Abnormal costs: Site clearance, remediation, and gas protection can create abnormal costs and uncertainty
- Planning and liability: Local authorities will expect environmental risk to be fully assessed and managed before granting consent
The Regulatory and Policy Drivers Behind Brownfield Redevelopment
The push to reuse brownfield land is no longer just a commercial decision, it’s being driven by regulators and policy.
Across the UK and beyond, policies are evolving to reduce land take, protect greenfield space, and restore biodiversity. For example:
- The EU’s 2050 “no-net land take” target is influencing national policies across Europe, pushing developers toward brownfield land
- The UK Government’s brownfield-first planning approach incentivises development on previously used sites through funding, tax relief, and planning policy. This approach is central to meeting the national target of building 1.5 million new homes by 2029, with a growing emphasis on reusing grey belt and brownfield land before considering greenfield alternatives. Councils are being urged to prioritise brownfield allocations in local plans, while government announcements increasingly link infrastructure funding and housing delivery to brownfield performance
- Biodiversity Net Gain (BNG) requirements and sustainability targets mean greenfield sites are becoming more complex and expensive to develop
For developers and investors, this means brownfield redevelopment is not only encouraged, it is increasingly necessary. Building on previously used land supports planning success, aligns with sustainability targets, and reduces exposure to biodiversity-related constraints.
The Economic Opportunity
Despite the technical challenges, brownfield development represents a significant economic opportunity:
- Land costs are typically lower than greenfield alternatives, especially in high-demand areas
- Urban sites are often closer to infrastructure, transport, and amenities, increasing end-use value
- Development potential is enhanced by targeted government support like Land Remediation Relief (up to 150% tax relief), brownfield grants, and infrastructure funds
- Wider economic benefits include new homes, jobs, local business growth, and revitalised communities. Research suggests brownfield regeneration could deliver over 1.3 million homes and create over 1 million jobs across the UK
Clear's Approach to De-Risking Brownfield Sites
We support developers across the UK with:
- Phase 1 Environmental Assessments – Identifying potential contamination or constraints early
- Phase 2 Site Investigations – Confirming risks through soil, groundwater and gas sampling
- Remediation strategies – Pragmatic, commercially-sensitive approaches to make sites suitable for use
- Cost planning support – Helping quantity surveyors and design teams budget for abnormals
- Verification & closure reporting – To satisfy planners, regulators, and funders
We understand the commercial drivers of development and deliver advice that reflects both regulatory expectations and real-world constraints.
Best Practices for Brownfield Success
- Start early – Commission a robust Phase 1 before purchase or design work begins
- Engage local planners and regulators – Understand what the council expects early on
- Use the right specialists – Inexperienced consultants can miss risks or over-specify costly solutions
- Plan for abnormals – Build contingency into budgets and contracts. Clear Environmental’s due diligence process is designed to identify abnormal costs early, often before land acquisition or design work begins. By conducting targeted desk studies and, where needed, intrusive investigations, we help clients uncover contamination risks, buried obstructions, or other ground-related surprises upfront. This enables better cost planning, informed land valuation, and fewer delays during construction
- Think strategically – Some risks can be managed through design or phased remediation. For example:
- Designing out risk by avoiding deep foundations in known contaminated zones
- Using clean cover systems in lieu of costly excavation in landscaped areas
- Treating hydrocarbon-impacted soils on-site to save on disposal fees
Ready to Unlock Your Site's Potential?
Clear Environmental help clients assess, investigate and remediate brownfield sites of all sizes. Our support is fast, commercially focused, and trusted by planners, developers, and investors alike.
Need support with a brownfield development? Get in touch today for honest, experienced guidance tailored to your site and your goals.
When a Phase 1 Desk Study identifies potential environmental risks, the next step is a Phase 2 Site Investigation, also called an intrusive investigation. This critical stage gathers real-world data to confirm or rule out contamination, protecting your project from unforeseen costs, planning delays, or environmental liabilities.
In this guide, we break down:
- How Phase 2 builds on Phase 1.
- The different investigation techniques (and when to use each).
- Typical timescales.
- How laboratory testing refines the site’s risk profile.
- What to expect at the end of a Phase 2 investigation.
How Phase 2 Builds on Phase 1
While a Phase 1 is based on desk research and a site walkover, a Phase 2 collects physical evidence through soil, groundwater, and ground gas sampling.
In short:
Phase 1 = Identify Potential Risks.
Phase 2 = Confirm or Dismiss Risks with Hard Data.
The findings from Phase 2 enable:
- Quantitative Risk Assessments (QRA) based on actual contamination levels.
- Decisions about whether remediation is necessary.
- Planning condition discharge if no unacceptable risks are found.
Phase 2 Site Investigation Methods
Different methods are used depending on the site, the anticipated risks, and the required depth of investigation:
- Best For: Shallow contamination, made ground assessment, visual soil profiling, locating foundations.
- Typical Depths: Up to 4 metres.
- Equipment: Mechanical excavator or hand-dug.
- Best For: Shallow contamination, installation of ground gas and groundwater wells, restricted access sites, cost-effective sampling.
- Typical Depths: Generally 5–6 metres, but can extend up to 10 metres depending on ground conditions.
- Equipment: Window sampling rig (tracked or towed).
- Best For: Deeper soils, groundwater sampling, ground gas monitoring, and collecting geotechnical data.
- Typical Depths: Up to 30 metres or more.
- Equipment: Cable percussion drilling rig.
- Best For: Hard ground, bedrock investigations, and installation of deep groundwater wells.
- Typical Depths: Up to 100 metres or more.
- Equipment: Rotary drilling rig (open hole, cored, or augered).
Tip: On smaller development sites, a combination of trial pits and window sampling often provides excellent coverage at a cost-effective price.
Types of Laboratory Testing During Phase 2
After sampling, the materials collected are sent for laboratory analysis to determine contamination levels:
- Soil Testing:
- Heavy metals (e.g., lead, arsenic)
- Hydrocarbons (TPH, PAHs)
- Asbestos in soil
- Emerging contaminants (e.g., PFAS)
- Groundwater Testing:
- Soluble contaminants (e.g., hydrocarbons, BTEX, solvents)
- Metals in solution
- PFAS detection
- Ground Gas Monitoring:
- Methane, carbon dioxide, oxygen concentrations
- Flow rates (for CS classification)
The results are then compared against appropriate assessment criteria to determine whether remediation is needed.
What Happens After Phase 2 Sampling?
1. Data Analysis and Quantitative Risk Assessment (QRA):
Risk to human health, controlled waters, or property assessed.
2. Conceptual Site Model Update:
Confirmed pollutant linkages mapped and risk-ranked.
3. Decision Point:
No significant risks: Reporting and planning condition discharge.
Significant risks: Recommend remediation (Phase 3).
Phase 1 vs Phase 2 - Quick Comparison Table
FAQs About Phase 2 Site Investigations
What happens if contamination is found in a Phase 2?
If contaminants exceed safe levels, a Remediation Strategy (Phase 3) will be needed to outline how risks will be managed.
Can a Site Investigations rule out the need for remediation?
Yes — many sites require no further action after a properly scoped Phase 2 investigation.
Is ground gas monitoring always required during a Phase 2?
Not always. It depends on the site's history, geology, and desk study findings.
Why a Clear Phase 2 Strategy Matters
A well-designed Phase 2 Site Investigation provides confidence, clarity, and control.
It ensures you're fully informed about site risks, avoids unnecessary remediation, and moves your project efficiently through planning.
At Clear Environmental, we tailor Phase 2 investigations to your site. No over-scoping, no hidden costs, just clear advice.
If your Phase 2 results raise concerns, understanding how to move forward with proportional, commercially realistic remediation is crucial.
To learn what happens next from Phase 2 to Remediation Click Here.
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What is a Phase 1 Desk Study (Preliminary Risk Assessment)?
A Phase 1 Desk Study (Preliminary Risk Assessment) is an initial environmental assessment that researches a site’s history and conditions to identify potential contamination risks.
Whether you're planning to develop land, submit a planning application, or purchase a brownfield site, understanding environmental risks early is essential.
A Phase 1 Desk Study (also called a Preliminary Risk Assessment) is the first critical step in managing those risks efficiently, helping avoid costly surprises later in your project.
This guide explains exactly what a Phase 1 involves, why it’s required, and what you can expect from the process.
What is a Phase 1 Desk Study?
A Phase 1 Desk Study is a preliminary environmental assessment that evaluates the potential for land contamination based on historical and current land uses.
It is called a “desk study” because it mainly relies on reviewing existing records and data sources, alongside a site visit.
It does not involve any intrusive ground investigation, that's reserved for Phase 2 if risks are identified.
In simple terms:
A Phase 1 identifies if there’s a potential problem — before you commit to site purchase, design, or construction.
Why is a Phase 1 Desk Study Needed?
A Phase 1 is often required to:
- Support planning applications (especially brownfield or previously developed sites).
- Satisfy lender due diligence for property transactions.
- Manage liability and avoid unexpected abnormal costs.
- Confirm if further investigations (Phase 2) are needed.
Without a Phase 1, local authorities, insurers, and funders may refuse to progress development or financing.
Key Components of a Phase 1 Desk Study
A thorough Phase 1 typically includes:
What Does a Phase 1 Report Contain?
A typical Phase 1 Desk Study Report will include:
- Executive Summary (key findings and recommendations).
- Site location and description.
- Historical land use review (maps and aerial photography).
- Environmental setting (geology, hydrology, groundwater).
- Regulatory database review (permits, enforcement notices, pollution incidents).
- Walkover survey findings (including annotated site photos).
- Preliminary Conceptual Site Model (CSM).
- Risk assessment and clear conclusions.
- Next steps, if further investigation is needed.
At Clear Environmental, our Phase 1 reports are concise, commercially-focused, and designed to satisfy planning authorities and lenders without unnecessary complexity.
How Long Does a Phase 1 Desk Study Take?
Most Phase 1 assessments can be completed within 10 Days.
We also offer fast-track services if you’re working to tight planning or transaction deadlines.
Phase 1 Desk Study vs. Environmental Search: What's the Difference?
Key point: An Environmental Search is not a substitute for a Phase 1 — it’s simply a basic desktop screening.
Why Clear Environmental for Your Phase 1?
A Phase 1 Desk Study isn’t just a box-ticking exercise, it’s your first opportunity to manage risks, reduce abnormal development costs, and protect your investment.
At Clear Environmental, we combine technical expertise with commercial insight to deliver Phase 1 Reports that meet planning, legal, and financial requirements quickly and clearly.
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FAQs About Phase 1 Environmental Desk Studies
When should I commission a Phase 1 Environmental Report?
Ideally before site acquisition or at the earliest planning stage, so risks and costs are identified early.
Will a Phase 1 Desk Study always recommend a Phase 2 Site Investigation?
No — many sites with clean histories and no risk linkages can be signed off at Phase 1.
Who needs a Phase 1 Environmental Desk Study?
Developers, property investors, planners, architects, solicitors, and lenders commonly require Phase 1 studies.
Will the council accept my Phase 1 report for planning?
Yes — provided it follows UK guidance (such as EA Land Contamination Risk Management (LCRM)) and is prepared by qualified specialists.
What happens if my Phase 1 shows contamination risks?
We’ll outline the recommended Phase 2 site investigation scope and cost early, so you remain in control.
FAQs About Contaminated Land Assessments
What is a contaminated land assessment?
A contaminated land assessment identifies whether land poses environmental or health risks, helping manage liabilities before development or purchase.
What is the difference between Phase 1 and Phase 2?
Phase 1 is a desktop and site walkover study identifies potential risks. Phase 2 collects soil, water, and gas samples to confirm actual contamination.
How long does a Phase 1 Environmental Report and Phase 2 Site Investigation take?
A Phase 1 takes 10 days. A Phase 2 takes 4-6 weeks depending on complexity.
What happens if contamination is found during a Site Investigation?
A remediation strategy is developed to remove or manage the risks to acceptable levels.
Do I always need a Phase 2 investigation?
Not always — if Phase 1 finds no significant risks, Phase 2 may not be necessary.
FAQs About Contaminated Land Assessments
What’s a Ground Gas and Vapour Strategy (GGVS)?
A GGVS is a targeted investigation to assess the presence and risk of gases such as methane, carbon dioxide, and vapours. It typically involves installing monitoring wells, conducting several monitoring visits, and using standards like CIRIA C665 and BS8485 to determine whether protection is needed.
Do I need gas monitoring for a small extension in RBKC?
Not necessarily. If the Phase 1 Ground Gas Risk Assessment confirms no credible risk — for example, if the site is underlain by intact London Clay with no Made Ground — monitoring may not be needed. In low-risk situations, RBKC may accept the installation of basic gas protection measures with a verification statement instead.
How long does a ground gas investigation take from start to finish?
The monitoring phase typically requires 3 - 6 visits spread over a few weeks, depending on site complexity and weather pressure conditions. Including report preparation, the whole process can take around 6 - 12 weeks.
Can I reuse historical ground gas data for planning?
Yes — provided the data is recent, reliable, and representative of current conditions. Clear Environmental reviews historic site investigation records early to help reduce costs and avoid unnecessary repeat monitoring.
What happens if gas risks are confirmed?
If gas concentrations exceed safe thresholds, you’ll need to install mitigation measures such as membranes, venting layers, or structural barriers. Clear Environmental will design a practical, proportionate solution and prepare the necessary Remediation and Verification reports.
What should be included in the Ground Gas Verification Report?
The Verification Report must include photographic evidence, product specifications, a signed statement of installation quality, and confirmation that gas protection was installed in accordance with RBKC expectations. For some projects, additional tracer gas testing may be required.
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