Phase 1 Desk Study
ESP’s Phase 1 Desk Studies provide thorough site appraisals that identify potential environmental and geotechnical constraints at an early stage
A phase 1 desk study is a preliminary risk assessment that evaluates the presence of contamination, its nature, and the extent of it on a development site.
Evaluation of the site’s environmental setting is also completed to identify possible environmental and human receptors and ultimately to assess Plausible Pollutant Linkages (PPL’s).
Usually, a desk study is completed in tandem with a walkover survey completed by one of our consultants, although it is feasible to conduct a desk study without a walkover.
A desk study report, inclusive of the valuable information gathered about the site enables an effective and cost-efficient ground investigation to be developed.
What is a Phase 1 Desk Study?
Recent Phase 1 Desk Studies
Case Study 1: Residential Development, Cardiff
- Overview: We delivered an integrated geotechnical and geoenvironmental Desk Study to inform the feasibility and masterplan for this proposed residential development on a currently vacant area of land in Cogan, near Cardiff. Our assessment was delivered on time and within budget for a multi-client project team. An initial Desk Study assessment was commissioned in advance of other works. The aim was to determine the likely Conceptual Ground Model (CGM) for the site, including a review of the history and environmental context alongside the anticipated geological conditions.
- Action: We identified a CGM that comprises a level plateau leading to a steeply sloping site, bordered by two major roads, a railway and the River Ely. Ground conditions comprise very thick Made Ground, followed by low strength/highly compressible alluvial deposits and bedrock of the Jurassic and Triassic. Some of the strata have the potential for significant pyritic heave. The land was occupied by railway lines and sidings, with extensive earthworks recorded, linked to these historical uses.
- Findings: The findings of our site investigation are to be used for early decisions on development feasibility, outline design and will be supplemented by ecology and traffic assessments. Once the feasibility of the development is confirmed, it will be necessary to undertake an exploratory investigation. The aim of this will be to confirm the Conceptual Ground Model from the Desk Study and address other aspects in detail, such as the potential for contamination to be present, geotechnical stability, flood risk, and sustainable drainage options.
Case Study 2: Residential Development, Blaenllechau
- Overview: The site investigation commenced with a desk study including a review of the site history and environmental context alongside the anticipated geological model for the site, including a preliminary Coal Mining Risk Assessment. The works from the initial desk study and site investigation were required to take into account the relatively large dwelling proposed and the steep slope on which it is to be situated.
- Action: The walkover aspect of the Desk Study allowed the revised scoping of an investigation that utilised investigation techniques and equipment suited to the limited access nature of the site and was required to overcome some significant constraints, including working on slopes, heavy vegetation and limited access from the site entrance. The investigation comprised hand held windowless sampling and shallow hand excavated trial pits which were aimed at providing geotechnical information and to allow sampling of soils as part of a contamination assessment. It was also necessary to undertake a preliminary assessment of infiltration testing in order to determine if sustainable drainage could be considered. As access was not available to large plant, the use of Falling Head Infiltration Testing was implemented.
- Findings: The findings of the investigation and assessment were used to aid detailed design of the development as part of a planning application and included consideration of contamination, foundation options tailored to the proposed construction and the potential for slope instability.
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What Is Included in a Phase 1 Desk Study Report?
A desk study is always completed at the inital stages of a site assessment to inform a site investigation report. This exercise can also include a visual survey of the site, also known as a site walkover survey.
Important information compiled in the report may include:
- Mapping & Historical Land Use Records: Analysis of Ordnance Survey maps, town plans, and aerial imagery to evaluate past and current land usage.
- Flood Risk Assessment: Review of flood potential using Environment Agency data and British Geological Survey (BGS) records.
- Geological Conditions: Assessment of both solid and drift geology through British Geological Survey maps and borehole data.
- Groundwater Vulnerability: Classification of aquifer status and potential contamination risks via Environment Agency resources.
- Seismic Activity: Examination of earthquake records within a 1km radius based on British Geological Survey reports.
- Local Authority Consultation: Engagement with Environmental and Planning Units to gather site-specific regulatory insights.
- Subsidence & Ground Stability: Evaluation of subsidence risks using geological maps, borehole indexes, and on-site surveys.
- Slope Stability Analysis: Identification of landslide or erosion risks through site inspections and topographic assessments.
- Brine Subsidence Risk: Investigation of potential ground subsidence in areas with historical brine extraction.
- Mining & Excavation History: Review of both historical and active surface and underground workings from public records.
- Coal Mining Risk Assessment: Coal Authority reports to determine mining-related ground stability risks.
- Landfill & Waste Site Proximity: Identification of active or historic landfill sites within 500m of the location using Environment Agency and local authority records.
- Radon Risk Assessment: Evaluation of radon exposure potential based on UK Health Security Agency and BGS data.
- Ecological & Environmental Constraints: Preliminary ecological assessment using walkover surveys and English Nature databases.
- Petroleum Storage & Contamination Risks: Records search via the Petroleum Licensing Officer for evidence of fuel storage or leaks.
- Planning & Development History: Examination of local authority planning portals for past applications and site approvals.
- Invasive Plant Species Survey: Identification of invasive species (e.g., Japanese Knotweed) through walkover inspections.
- Archaeological & Heritage Considerations: Preliminary assessment of archaeological significance using National Monument Records.
Sources of Information We Use for a Phase 1 Desk Study
A desk study is always completed at the inital stages of a site assessment to inform a site investigation report. This exercise can also include a visual survey of the site, also known as a site walkover survey.
Important information compiled in the report may include:
- Mapping & Historical Land Use Records: Analysis of Ordnance Survey maps, town plans, and aerial imagery to evaluate past and current land usage.
- Flood Risk Assessment: Review of flood potential using Environment Agency data and British Geological Survey (BGS) records.
- Geological Conditions: Assessment of both solid and drift geology through British Geological Survey maps and borehole data.
- Groundwater Vulnerability: Classification of aquifer status and potential contamination risks via Environment Agency resources.
- Seismic Activity: Examination of earthquake records within a 1km radius based on British Geological Survey reports.
- Local Authority Consultation: Engagement with Environmental and Planning Units to gather site-specific regulatory insights.
- Subsidence & Ground Stability: Evaluation of subsidence risks using geological maps, borehole indexes, and on-site surveys.
- Slope Stability Analysis: Identification of landslide or erosion risks through site inspections and topographic assessments.
- Brine Subsidence Risk: Investigation of potential ground subsidence in areas with historical brine extraction.
- Mining & Excavation History: Review of both historical and active surface and underground workings from public records.
- Coal Mining Risk Assessment: Coal Authority reports to determine mining-related ground stability risks.
- Landfill & Waste Site Proximity: Identification of active or historic landfill sites within 500m of the location using Environment Agency and local authority records.
- Radon Risk Assessment: Evaluation of radon exposure potential based on UK Health Security Agency and BGS data.
- Ecological & Environmental Constraints: Preliminary ecological assessment using walkover surveys and English Nature databases.
- Petroleum Storage & Contamination Risks: Records search via the Petroleum Licensing Officer for evidence of fuel storage or leaks.
- Planning & Development History: Examination of local authority planning portals for past applications and site approvals.
- Invasive Plant Species Survey: Identification of invasive species (e.g., Japanese Knotweed) through walkover inspections.
- Archaeological & Heritage Considerations: Preliminary assessment of archaeological significance using National Monument Records.
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Frequently Asked Questions
Why Do I Need a Phase 1 Desktop Study?
An effective phase 1 desk study is the foundation of a robust geoenvironmental assessment. ESP recommends utilising a Desk Study as part of most assessments as the potential savings (through focused/targeted follow-up work) can be significant.
Importantly, when developing a site, the Local Authority Planning Department will likely require a Phase 1 Desktop Study Report as part of the Planning application. ESP can also liaise with the Local Authority Environmental and Planning team on your behalf to ensure compliance and to understand site information.
Other valuable reasons for completing a phase 1 desk study include:
- Regulatory compliance
- Planning conditions (for validation or discharge of conditions)
- Building warranty (NHBC or similar)
- Risk identification and cost savings
- Financial and legal due diligence (e.g. for land purchases)
- Health and safety considerations
- Sustainability and environmental impact
How Long Does a Phase 1 Desk Study Take to Complete?
We can complete a comprehensive phase 1 desktop study along with a walkover survey within 7 working days.
Completion timescales do depend on our team’s availability and the complexity of the site conditions.
The time to complete a report is also influenced by:
- Access to the site.
- And, if required, the availability of the Local Authority’s Contaminated land or Environmental Unit to liaise with us regarding details of the development site.
What Happens After the Phase 1 Desk Study is Complete?
Once we have completed your Phase 1 Desktop Study ESP will provide you with your report via email.
Step 1: Submit Report To Local Authorities (As Required)
If the desktop study has been completed to comply with and satisfy Local Authority planning conditions the finalised report must be submitted to the Local Authority Planning Department.
Step 2: If Required, Complete Phase 2 Investigation
If the Phase 1 Desk Study recommends a Phase 2 site investigation ESP can also assist and guide you with this phase.
If we identify there are low or no risks as part of the phase 1 desk study, it may be the case that no further action is required.
Step 3: Develop Mitigation / Remediation Plans
If contamination is identified during a Phase 1 Desk Study or Phase 2 Site Investigation, remediation or mitigation plans may be required.
- Remediation focuses on removing or neutralising contaminants, using common methods such as excavation and disposal (dig and dump), soil washing, bioremediation (using microorganisms), chemical treatment, and groundwater pump-and-treat systems. Other techniques like soil stabilisation and vapor extraction help immobilise or remove harmful substances.
- The mitigation route focuses on reducing exposure risks rather than eliminating contamination. This can include capping contaminated areas with clean soil or concrete, installing permeable reactive barriers to filter contaminants, or adjusting site layouts to avoid high-risk areas.
Remediation and mitigation actions help ensure safe future development while minimising environmental and financial impacts.
Generally, investigations are completed as follows, and as required:
- Phase I Desktop Study
- Phase II Site Investigation (as required)
- Phase III Remediation Statement (as required)
- Phase IV Validation Report (as required)
If there are project time constraints and follow-up remedial action is probable, it may be possible to complete a Phase 1 and Phase 2 site investigation can be completed simultaneously.
What Guidance is Followed to Conduct a Phase 1 Desk Study?
Phase 1 Desk Studies are completed in line with Land Contamination: Risk Management (LCRM), the latest UK guidance that replaced CLR11 in 2019. LCRM provides a structured approach to assessing and managing land contamination risks, ensuring compliance with environmental regulations and planning requirements.
Assessments are typically overseen by the Local Planning Authority (LPA), with reports reviewed by Contaminated Land Officers or Building Control Teams. Each Local Authority may have specific requirements for contaminated land assessments, so the desk study must align with their planning conditions and regulatory expectations.
ESP stays up to date with current legislation and best practices, working closely with regulatory bodies to ensure our Phase 1 Desk Studies meet all compliance standards, streamlining approvals and mitigating risks for developers.
What is the Difference Between a Phase 1 Desk Study and Phase 2?
A Phase 2 desk study is usually conducted after the Phase 1 report is completed, and involves direct sampling and analysis of the development site using intrusive methods.
This is in comparison to the Phase 1 study which is focused on the gathering of existing information and a site walkover. The Phase 2 report provides a comprehensive understanding of the soil, ground, and possibly air at the site.
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Earth Science Partnership is a leading expert in phase 1 desk studies across Wales, England, Scotland, Northern Ireland and Ireland. We have decades of combined experience in our team of industry-recognised experts.
Our work, for homeowners, land owners, developers, and investors is completed in compliance with the latest, relevant industry best practices and guidance. We understand that every project is unique, so we deliver our services tailored to your needs.
If you’re looking to complete a phase 1 desk study, the ESP team can support you with a straightforward, cost-effective solution for your planning permission application.
Author
I am a UK Registered Ground Engineering Specialist and Chartered Engineering & Environmental Geologist with significant experience in Site Hazard Assessment, Remediation, Design, and Implementation across the Geoenvironmental and Geotechnical sectors in the UK and abroad.
I often work in multi-disciplinary teams advising other engineering and design professionals on the implications of ground hazards.
My work involves undertaking design, planning, management, and reporting of ground investigations. For example investigations for new developments and many bespoke studies including:
- Assessment of hydrogeological settings, materials for earthworks.
- Impact of abandoned mine workings.
- Remediation and stability assessment of soil and rock slopes/landslides, most notably the Pantteg Landslide in the Swansea Valley for which I have guided and presented assessments to Local Authority officers and the general public.