Phase 2 Intrusive Site Investigations For Planning Permission & Due Diligence
Phase 2 Intrusive Site Investigations, noted in the Environment Agency LCRM guidance as the second step of a Stage 1 Risk Assessment, are conducted following the identification of contamination risks at a site that require further investigation in order to quantify.
This initial assessment of contamination risk is carried out as part of a Phase 1 Preliminary Risk Assessment (Desk Study), which will also outline a scope of work for a Phase 2 Intrusive Site Investigation. Site investigations are likely to include targeted soil or water sampling, with analysis carried out in a UKAS accredited laboratory, and are essential in order to determine whether contamination is present at your site.
After first carrying out a Phase 1 Preliminary Risk Assessment (Desk Study), a Phase 2 Intrusive Site Investigation is the next stage in the assessment of potentially contaminated land and is a common requirement for everything from Environmental Due Diligence to supporting planning applications. If a desk study has identified that a site is potentially contaminated, a Phase 2 Intrusive Site Investigation will be required in order to fully assess the nature and extent of site contamination.
Where the Desktop Study identifies potential contamination a Detailed Site Investigation Report will also be required, including a site investigation documenting the characteristics of the ground, an evaluation of all potential sources of contamination and a risk assessment, together with an updated conceptual model.
– Example planning permission condition from Rushcliffe Borough Council
The Cost Effective Phased Approach - A Phase 2 Intrusive Site Investigation will build on the findings of previous investigations, with an aim to confirm whether suspected contamination is present at the site. It's important to adopt a phased approach in these kinds of assessments as it allows us to focus attention on particular areas of potential contamination at the site, in addition to, saving time and money through a more efficient sampling strategy. This approach also ensures that the appropriate laboratory testing is carried out, saving money by avoiding unnecessary tests and making sure the right contaminants are tested for so important elements aren't missed out. Throughout the Phase 2 Intrusive Site Investigation a 'Conceptual Site Model' (CSM) will be updated as new sources or pathways of contamination are identified, in order to determine the risk presented by contamination at the site.
Ask a question →What Does a Phase 2 Intrusive Site Investigation Include?
Soil & Water Sampling - A Phase 2 Intrusive Site Investigation will involve planning a sampling strategy for collecting soil samples from the site, taking into account any potential sources of contamination identified as part of the Phase 1 Preliminary Risk Assessment. For example, if hazardous substances are stored on a site it will be important to take samples from this area to identify any resulting contamination of the land. At this stage of a Phase 2 Intrusive Site Investigation the location and depths of samples will be determined along with the method of taking them. For example, for a site intended for redevelopment into residential land it will likely be important to sample shallow soils as this is an important pathway of contamination that may affect the future residents, this can usually be carried out using a handheld window sampler.
Once the sampling strategy for the intrusive site investigation has been planned, samples will be taken from site. It may be the case that unforeseen constraints limit the sampling and the sampling carried out may differ from the original strategy. The limitations will be noted in the report but will rarely invalidate an investigation entirely.
UKAS Accredited Laboratory Testing - After samples are collected they are sent to our UKAS accredited laboratory for analysis that may include testing for common contaminants, such as heavy metals and hydrocarbons, but will be specific to every site investigation. For example, on some sites, it's important to test for the presence of asbestos. Once the laboratory testing is complete, the results will be assessed with reference to industry standard screening values that act as threshold values for determining if a site can be considered 'contaminated'.
Ground Gas Monitoring - On sites where a potential ground gas risk has been identified, ground gas monitoring is required. This process includes the drilling of boreholes and installation of gas monitoring wells, followed by a series of site visits to monitor ground gas concentrations over time. The data collected is then assessed and used to update the Conceptual Site Model (CSM) within the Phase 2 Intrusive Site Investigation. Ground gas monitoring is a critical component in evaluating risks associated with gases such as methane and carbon dioxide, particularly on sites with made ground or a history of landfill use.
Oakshire Environmental recently completed a phase1 and 2 contamination investigations for our residential planning application. The site itself had a complicated history as it was part of a decommissioned Waterworks. Over the many months Joe and Louis were very supportive and flexible in helping us answer all the contamination officers' questions. They helped us all the way until we received approval to build. For the phase 2, we were concerned about the intrusive nature of the site excavations. Joe was very helpful in explaining how it would be implemented so as not to impact the site. True to his word, on the day, the excavations and tests went smoothly and was finished within 4 hours.
- Chris Green
When Do I Need A Phase 2 Intrusive Site Investigation?
It's not possible to determine actual contamination levels present at a site without carrying out a Phase 2 Intrusive Site Investigation. Desk studies can only identify potential sources of contamination and without collecting and testing soil or water samples, actual contamination levels cannot be identified.
Comply with planning conditions - Planning legislation dictates that the land contamination risk assessment process is an integral part of any development project and if the Phase 1 Preliminary Risk Assessment for a development identifies the need for further investigation, no development will be allowed until a Phase 2 Intrusive Site Investigation is carried out.
Carrying out an intrusive site investigation may also allow you to avoid unnecessary and costly remediation work as it will provide all the necessary information to inform a Phase 3 Remediation Options Appraisal & Strategy.
Meet Our Site Investigation Consultants
Louis Turner, Technical Director - Having graduated from the University of Nottingham with a degree in Environmental Science, Louis is recognised for his technical leadership and precision in environmental consultancy. Louis provides strategic oversight across all service areas, ensuring projects meet the highest standards of compliance, accuracy, and environmental responsibility. Louis directs contaminated land investigations, from desk-based risk assessments to intrusive site surveys. He ensures soil and ground gas analysis is conducted to UKAS-accredited standards, producing clear, evidence-based reports that support planning applications, regulatory approvals, and safe development decisions.
Joe Turner, Operations Director - Providing practical expertise and a client-focused approach, Joe ensures that every project is delivered quickly, efficiently, and without unnecessary hassle. He has successfully managed a wide variety of project types across the consultancy, bringing a wealth of operational knowledge and a reputation for keeping projects on track. Joe's leadership guarantees a smooth process for clients, from initial enquiry through to final reporting. Joe oversees contaminated land investigations, coordinating desk studies, site surveys, and remediation works. His operational management ensures that soil sampling, ground gas monitoring, and reporting are completed seamlessly, giving clients confidence in compliance and project delivery.
Richard Turner, Director - With over 30 years of experience in site development, he provides invaluable insight into pragmatic solutions that balance costs, practicalities, and client objectives. Richard has a detailed understanding of building regulations and a clear sense of what is and isn't possible on site, making him a trusted advisor for developments of all sizes. Richard applies his site development expertise to contaminated land investigations, ensuring that remediation strategies are practical, cost effective, and achievable on site. His focus on feasibility helps clients move forward with confidence.
Request A Phase 2 Intrusive Site Investigation
Contact us for an informal discussion about your requirements or, if your requirements are more complex, a more formal consultation may be necessary. Following initial consultation we can provide an outline proposal detailing how we can help and the costs involved. If you're looking for more information about our services or our company then complete the below contact form and we will endeavour to respond to your enquiry in a timely manner, alternatively, give us a call on 0800 433 2906 and our experienced consultants can provide actionable advice and guidance.
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References
British Geological Society. BGS GeoIndex
BSI Group. Code of practice for the design of protective measures for methane and carbon dioxide ground gases for new buildings
CL:AIRE. Category 4 Screening Levels (C4SLs)
Environment Agency. Land contamination risk management (LCRM)
Land Quality Management. The LQM/CIEH S4ULs for Human Health Risk Assessment
US EPA. Regional Screening Levels (RSLs)