What is a Phase 1 Desk Study?
A Phase 1 Desk Study is a preliminary risk assessment from the collation and review of published information regarding a sites historical, geological and environmental setting.
The purpose of a Desk Study is to determine a preliminary risk rating and to plan the subsequent stages of the site investigation. This is achieved by identifying any potential ground related hazards and potential contamination sources, pathways and receptors where there could be potential risks to human health, vegetation, controlled waters, structures and services.
Do I need a Phase 1 Desk Study?
There are generally two scenarios for requiring a Phase 1 Desk Study:
- Developing a Site – a Phase 1 Desk Study (Preliminary Risk Assessment) will generally be a requirement in the Planning Conditions set out by the Local Authority Planning Department. Therefore, A Desk Study Report is carried out to satisfy the various regulatory requirements of Planning Departments, Environmental Health Departments, the Environment Agency, Building Control Departments and National House Building Council (NHBC).
- Property Transactions (Due Diligence) – before buying a site or property, as a minimum requirement we recommend a Desk Study is carried out to identify and evaluate any potential risks associated with the site and the liabilities which the prospective buyer will acquire.
When should a Phase 1 Desk Study be undertaken?
A Phase I Desk Study is normally carried out at the start of the site investigation process. The Desk Study characterises the site and provides information and an initial conceptual ground model for the remainder (if required) of the site investigation process.
What is included in a Phase 1 Desk Study Report?
At Sub Surface our Phase 1 Desk Study Reports include:
- Site Details – Site Location, Site Boundaries, Present Land Use, Proposed Site Use, Details of the Walkover Survey
- Historical Appraisal – a review of historical Ordnance Survey plans of the past uses and structures on site and the immediate surrounding area.
- Geological Appraisal – Artificial Ground, Superficial Strata, Bedrock, Mining, Geomorphology, Natural Ground Subsidence, Radon Gas, etc.
- Environmental Appraisal – Potential Contamination Sources, Pollution History, Landfill Sites, Hydrogeology and Hydrology, Flooding, etc.
- Conceptual Ground Model – a preliminary risk assessment of potential ground related hazards and potential contamination sources, their pathways and receptors where there could be potential risks to human health, vegetation, controlled waters, structures and services.
- Site Investigation– Recommendations (if required) including, Contamination Analysis, Ground Gas Monitoring, etc.
What is a Walkover Survey?
All of our Phase 1 Desk Studies include a Walkover Survey (Site Reconnaissance). A Walkover Survey is a visit to site by an Engineer to undertake a thorough inspection of the site to confirm, amplify and supplement the information within the Desk Study and to visually and olfactorily assess any potential zones of contamination.
What happens if the site is within a Coal Mining Area?
For sites located within an area that might be affected by mine workings (parts of Lancashire, Manchester, Yorkshire, Derbyshire, West Midlands, etc.), a Coal Authority Mining Report will be required and incorporated within the Phase 1 Desk Study.
If the Coal Authority Mining Report indicates that there is a possible risk to ground instability and subsidence, or if we believe there is a potential for unrecorded mines beneath the site or mine entries, a Coal Mining Risk Assessment will be required.
What are the Benefits of a Phase 1 Desk Study?
There are many benefits of carrying out a Phase 1 Desk Study prior to commencing an intrusive site investigation or purchasing a site, including:
- Identifying potential geotechnical, environmental and health and safety issues, which could dramatically affect the site investigation and/or the project.
- The formulation of a preliminary risk assessment allows for efficient targeting of project resources and avoids money being wasted on inappropriate intrusive ground investigations.
- Provide early warning of possible delays or budget implications through previously unknown site characteristics.
- Provides information on possible contaminants and anticipated areas of contamination.
What are the Limitations of a Phase 1 Desk Study?
A Phase 1 Desk Study is a desk-based report with no intrusive ground investigation. Therefore, occasionally additional ground related hazards and/or contamination issues may be present which are not identifiable from the published information.
What happens after the Phase 1 Desk Study is complete?
For discharging Planning Conditions, your Phase 1 Desk Study should be submitted to the Local Authority Planning Department. If the Phase 1 Desk Study recommends a Phase 2 Site Investigation, you should contact your Regional Sub Surface Office to provide you with a quote.
We recommend that when developing a “brownfield site” a phased investigation is undertaken in order that each phase informs the next. A typical phased investigation comprises the following:
- Phase I Desktop Study
- Phase II Site Investigation (if required)
- Phase III Remediation Statement (if required)
- Phase IV Validation (if required)
Can I undertake a Phase 1 Desk Study and a Phase 2 Site Investigation simultaneously?
Yes. To meet the requirements of some of our Clients, Sub Surface can carry out Phase 1 Desk Studies and Phase 2 Site investigations simultaneously. This is ideal for Clients on very tight timescales with deadlines to meet. An Engineer will review the raw desk study data and if required, a revised quote for the site investigation will be provided prior to the intrusive site investigation commencing.
How can I get a quote for a Phase 1 Desk Study?
If you would like a quote for a Phase 1 Desk Study. Please contact your Regional Sub Surface Office (regional map via link) and email the following information (where necessary/available):
- Site Location Plan – showing the redline planning application boundary
- Existing Site Plan
- Proposed Development Plan
- Planning Conditions