A to Z of Geoenvironmental Services

Longstanding expertise in geoenvironmental engineering allows us at CGL to provide specialist and pragmatic advice and support across a broad range of skills that is at the forefront of industry knowledge.


Ground Source Heat Pump Feasibility

Incorporating sustainable, environmentally friendly systems into developments, both new-build and retrofit, has never been more important.  Increasingly, our clients are placing more importance on the social responsibility of their construction plans.  The incorporation of such measures is of high importance to Planning Authorities as well.  The recently introduced Planning Policy Statement 22 (PPS22) sets out the Government's policies for renewable energy, which planning authorities should consider when preparing local development documents and when making planning decisions.


To support developers, designers, architects, and structural engineers, CGL can provide a Ground Source Heat Pump (GSHP) Feasibility Assessment of the site and proposed development.  This GSHP Feasibility Assessment will detail the geothermal properties of the underlying geology, key to designing a cost and energy effective solution and one that will stand the test of time.  A basic determination of the likely best solution for the development in question will then be given.  The GSHP Feasibility Assessment can be provided as a stand-alone report or incorporated within a CGL desk study/interpretative report as part of a holistic approach.


For more information about GSHP Feasibilities please contact Dan Matthews at our Head Office on 01483 310600 or email Dan at DanM@cgl-uk.com

Contamination Risk Assessments
Contamination Risk Assessments

For any prospective site development, identification of contamination always poses the question as to what is the risk and how much will it cost to rectify such an issue.  On sites such as these CGL is able to provide robust qualitative and quantitative assessments and pragmatic solutions based on many years of experience and contributions to national published guidance.

Basing these risk assessments on the context of the site and existing or proposed development, we are able to determine:

  • Firstly, whether remediation is necessary; and
  • Secondly if so, recommend and design the scope of such works.  

We are very mindful to consider our clients’ legal obligations and their commercial objectives before recommending remediation and significant clean-up, and in our advice seek to achieve a value added solution within set timescales.  

CGL has specialist in-house geotechnical and geoenvironmental skills, focussing primarily on human health risk modelling (based on use of the UK government CLEA framework), groundwater risk modelling using the Environment Agency approved methods, remedial targets methodology (P20), and the modelling software CONSIM. 

For those sites with gas-related issues, we are able to offer advice and risk assessment, with bespoke protection measuring solutions where appropriate.  In past assessments, the use of a robust risk assessment approach has demonstrated that sites believed to require significant remediation, could be developed with reduced intervention.

For further information about Contamination Risk Assessments please contact Jo Strange at our Head Office on 01483 310600 or email Jo at JoS@cgl-uk.com.

Due Diligence Appraisals
Due Diligence Appraisals

CGL is a geotechnical and geoenvironmental consultancy, working at the forefront of the construction industry, offering advice on ground-related liabilities associated with sites throughout the UK.  For those wishing to buy or sell property, or simply assess the risks associated with ownership and stewardship of land, we are able to provide a range of site appraisals, including environmental audits and site assessments.

As specialists in contaminated land, ground gas risk assessments and geotechnical appraisals, we can provide the necessary research and reports on all phases of investigation including desk studies, intrusive investigations, remediation and verification programmes.  

At CGL, we undertake to provide our clients with a separate Site Appraisal Report on completion of an intrusive investigation phase. All surveys are aimed at identifying our client’s critical environmental risks, providing advice on mitigation and offering bespoke solutions.  We are also able to supervise the survey elements of environmental permit applications, overseeing the application and permit surrender processes for our clients.

For further information about Due Diligence Appraisals please contact Jo Strange who, as a  Specialist in Land Contamination (SiLC), can provide guidance at all stages of the appraisal process at our Head Office on 01483 310600 or email Jo at JoS@cgl-uk.com.

Environmental Impact Assessments
Environmental Impact Assessments

Under current planning guidance in compliance with EU Directive 97/11/EC, Environmental Assessments (EIA) are required for major development schemes (Schedule 1) or other schemes deemed likely to pose a risk to the environment (Schedule 2). CGL has provided specialist support on a number of EIA’s for major and high risk development schemes, in particular providing information on ground conditions and contamination issues and the associated impacts.  For instance, CGL was involved with the redevelopment of Minoco Wharf, the major residential development West of Waterlooville, the commercial development for a retail superstore in Bromley and numerous Thames-side developments such as Battersea Reach.

An EIA considers the potential environmental impacts from proposed land use changes and looks to measure environmental, economic and social issues in an integrated way.  It is therefore an integral part of the pre-planning stage of most major projects, describing a procedure that must be followed before development consent can be granted. The EIA is submitted to the planning authority as part of a planning application and the more comprehensive and informed the report, the easier and swifter it is for the public body to make a decision to grant an application.

An EIA covers a wide range of topics, including, but not limited to air quality and odour, archaeology, contaminated land, drainage and flooding, ecology, geology, invasive plants, landscaping, microclimates, noise and vibration, species control, waste, water resources, wetlands and marine.

Although the current planning system was significantly revised in early 2012, removing much of the current guidance especially related to assessment of contamination, the requirement for EIA’s will still remain, possibly with even more emphasis on demonstrating sustainable development.

CGL has the necessary expertise to manage the delivery of EIA’s for a wide range of sectors, guiding our clients through the process to ensure it is produced on time and within budget. CGL staff include registered environmental auditors and Chartered Environmentalists with specialist experience in assessing the sustainability of ground and contamination related activities.  

Following the requirement for an EIA as part of the planning application for a site, CGL produces an Environmental Statement on the relevant topic(s), which encompasses the findings of site assessment with development associated impacts within a non-technical summary document.

For further information about Environmental Impact Assessments please contact Jo Strange at our Head Office on 01483 310600 or email Jo at JoS@cgl-uk.com. Or contact Heather Oatridge at our Harrogate Office on 01423 276000 or email Heather at HeatherM@cgl-uk.com.

Geoenvironmental Desk Studies
Geoenvironmental Desk Studies

CGL provide desk studies to our clients in the construction industry for projects both large and small. These desk top surveys can be tailored to meet the requirements of each client as either individual reports submitted as part of the planning process, or part of the intrusive investigation documentation.


Desk studies form an essential part of the investigation process for all sites whether brownfield or greenfield. CGL have long championed the cost effectiveness of the holistic site investigation that encompasses both the substructure design and contamination mitigation. All desk studies will require Conceptual Site Models (CSM) for contamination risk and need to consider past land use, geology both published and unpublished, and environmental incidents in context and with a view to eventual construction.


CGL do not provide simply a web-based generic collection of data without project context, but incorporate the requirements of industry based standards from the Associated Geotechnical and Geoenvironmental Specialists (AGS) and the current BS5930 and BS10175.


Typically, such desk studies can be assembled in a matter of a few days at relatively low cost by our experienced geotechnical and geoenvironmental staff and are quality audited by highly experienced staff. Such investigation has the potential to save clients considerable amounts of money and time in both the planning and construction process.


For further information about Geoenvironmental Desk Studies please contact Nick Langdon at our Head Office on 01483 310600 or email Nick at NickL@cgl-uk.com.



  1. ICE Design and practice guide:  Contaminated land investigation, assessment and remediation, 2nd Edition N Langdon and J Strange, Thomas Telford 2008
  2. Effective contamination investigation is a measure of success N Langdon The Civil Engineering Surveyor March 2008
Geoenvironmental Site Investigations
Geoenvironmental Site Investigations

Poorly informed and executed site investigation works ……expose investigation personnel…and the general public to unacceptable health risks.”  And of course it follows that the client too will be at risk in a number of ways.

At CGL we aim to balance our clients’ concerns on investing time and money into one of the least visible elements of the construction process with experienced guidance on what can be achieved with a good site investigation.  Conversely we caution on the risks of failing to provide adequate design data.

Our experienced geoenvironmental specialists and engineering geologists work across the UK on investigations ranging in size from a few £1000’s to £0.5million for clients as varied as individual householders, to major residential developers and commercial organisations, and to the power and rail industries.  

Our experience and knowledge of the industry ensure we use appropriately experienced and quality driven investigation contractors and soil and contamination testing laboratories so that our factual information is compliant with BS5930, BS10175 and MCERT compliant accreditation, and supports our interpretative and design reporting.  

Recently completed CGL site investigations have included the investigation of a former agro chemical works in Kent in preparation of sale, a comprehensive investigation of a site known to be at risk of thorium contamination, and a boatyard site with former industrial use.

We work closely with regulators from the Environment Agency and local authorities to develop confidence in the processes of investigation and the eventual mitigating outcomes.  Our experience with quantitative risk assessments for groundwater, gas and soils allows us to provide value added solutions for brownfield sites to our clients.

For further information about Site Investigations please contact Jo Strange at our Head Office on 01483 310600 or email at Jo at JoS@cgl-uk.com.



  1. ICE design and practice guide: Contaminated Land, investigation, assessment and remediation 2nd Edition N Langdon and J Strange
Independent Verification
Independent Verification

The final element of a successful development scheme on contaminated land sites is the formal confirmation that the remediation measures have been implemented and that the risks have been removed or reduced to an acceptable level.  Independent verification by a third party is normally essential to this process.


The verification process is frequently commenced by the production of a verification plan to demonstrate how the implementation of these works may be proven.    At CGL, we are able to provide the advice and documentation for our clients, negotiate with the regulators on the clients’ behalf to clarify the procedures and associated costs, and ultimately support the programme timing leading to a successful project. We can also assist with the providing of evidence where remediation works have been undertaken either, by inspection or test reports to comply with record-keeping requirements under CDM, or satisfying the regulator’s requirements in their capacity as statutory planning consultees or enforcers of environmental legislation.


Our services range from smaller inspections, validation testing and monitoring, through to full-time observation, management and supervision of remediation works, depending on project requirements. CGL’s reporting of validation evidence is tailored to meet our clients’ requirements and, subject to the works being compliant, will provide the recipients with clarification on any ground-related issues.  We regularly liaise with local authority planners, regulators and warranty providers to achieve closure on remediation issues, allowing for projects to successfully move forward through construction to occupation.


For further information about Independent Verification please contact Jo Strange at our Head Office on 01483 310600 or email Jo at JoS@cgl-uk.com.

Landfill Management and Aftercare
Landfill Management and Aftercare

The number of closed landfill sites across the UK are continuing to rise, representing a significant financial burden to the previous operator or site owner.  At CGL, we continue to support a number of clients facing these ground-related issues on aspects ranging from routine monitoring, HSE, ATEX and DSEAR assessments, and computer modelling of gas generation rates through to long term leachate concentrations and biodegradation timescales.

We provide ground solutions assisting with long term capital infrastructure requirements, medium term site contaminant and collection measures, and in the shorter term, contaminant migration.  Added to this, our team’s experience of data assessment and modelling enables cost effective site management whilst ensuring protection of human health and the local environment.  

In particular, our understanding of modelling for closed landfill sites, including GasSim, allows the extraction and analysis of raw data and provision of long term management solutions for budgeting purposes, and our team are often appointed to support the design of the associated infrastructure requirements thereafter.  We have experience of designing protection measures for commercial developments across former landfill sites in Yeovil, Port Solent and Feltham.

With publically accessible sites, the regulations for Dangerous Substances in Explosive Atmospheres (DSEAR) require ATEX assessments to be conducted, which allows accessible infrastructure to be zoned appropriately.  As a result of these assessments our clients have implemented protection measures to ensure public safety.

We have also provided design support for on site restoration works, including the design and on site supervision of reed beds for effluent treatment, and of barrier cut-off walls to mitigate risk to surrounding land and properties from migration of landfill gas and leachate.

For further information about Landfill Management and Aftercare please contact Jo Strange at our Head Office on 01483 310600 or email Jo at JoS@cgl-uk.com.

Modelling Contaminant Flow
Modelling Contaminant Flow

Modelling of contaminant flow is an essential part of contaminated land assessment when a detailed quantitative risk assessment (DQRA) is required for the protection of controlled waters. Knowledge of contaminant mobility and environmental effects such as dilution, dispersion, retardation and degradation are important factors used to assess how a contaminant may travel through the ground beneath a site, migrating to groundwater abstraction points or surface water bodies.


At CGL we utilise software programmes such as the Environmental Agency Remedial Targets Methodology (EARTM) and ConSim, which are based on recognised assessment techniques, to determine the impact contaminants have on groundwater and surface water bodies. We have used these programs, successful negotiations with regulators and effective remediation outcomes in projects such as Lady Margaret Hall, Galaxy, Mildenhall, Boroughbridge and Nufarm, Belvedere.

These two programmes, whilst based on the same principles, offer different outputs: EARTM determines a remedial target for the site, and ConSim specifies the likely concentrations at the downstream receptor or compliance point based on concentrations at the site.  These levels include:


  • Level 1 Soil zone – basic assessment of leachate and pore water concentrations to determine if exceeding the stated water quality standards;
  • Level 2 Unsaturated zone and dilution at water table – assessment of mobilised contaminant concentrations immediately below the subject site and consideration of attenuation of contaminants within the unsaturated zone and dilution by groundwater flow;
  • Level 3 Attenuation in aquifer – assessment of contaminant concentrations in the saturated zone at the downstream receptor or compliance point. The effects of attenuation of the contaminants in the saturated zone are taken in account.


It is often the case that detailed modelling techniques can be used to ascertain what concentration contaminants could remain on site without risk to controlled water receptors.  This is demonstrated by the examples we refer to above where determining the level of remediation required, by means of modelling, provided cost savings for these projects.

For further information about Modelling Contaminant Flow please contact Jo Strange at our Head Office on 01483 310600 or email Jo at JoS@cgl-uk.com.

Regulator Negotiations
Regulator Negotiations

As part of the broader construction industry, geotechnical and geoenvironmental consultancies are also subject to rigorous scrutiny by regulators from a construction and environmental perspective.  Regulation extends from conformance to Building Regulations, satisfying local authority Building Control Officers, to meeting environmental legislation requirements in consultation with Contaminated Land Officers, the Environment Agency and others.  As much of the work is risk-based, with designs and assessments based on judgement, experience and capability is of paramount importance in negotiating acceptable solutions.

CGL’s track record and credibility is recognised within the industry, providing confidence to the regulators that any negotiations in which we are involved will be based on a high degree of technical competence and understanding, with many possible implications having been considered prior to arriving at the solution.  From our client’s perspective, they can be secure in the knowledge that CGL will provide technically robust solutions minimising protracted negotiations and limiting further works or justification to meet regulator approval.

This skill and capability has many advantages, demonstrated on numerous schemes.  For example, at a recent site in Kent CGL acted as an independent validation and certification body for the design of a remediation scheme where the contract of sale for the site was related to the success of the scheme.  In this case, we were in constant negotiation with the Environment Agency to accommodate changing ground conditions whilst maintaining the environmental objectives that allowed the contract of sale to proceed.

In is not uncommon for CGL to be appointed by local authorities to act in support of the environmental regulators where they lack specific expertise, or perhaps where they are in dispute with developers over technical issues.  In these circumstances, our independent status and capability can work to the advantage of both parties.  This has enabled some larger developments to proceed to everyone’s satisfaction.

As a specialist consultancy, we can offer the independence of advice that is valued by both regulators and clients alike.  The reputation that CGL enjoys within the industry, respected by its peers, clients and others, is a powerful force in enabling successful negotiations to be concluded to the satisfaction of all.  

For further information about Regulator Negotiations please contact Ian Marychurch at our Head office on 01483 310600 or email Ian at IanM@cgl-uk.com.

Remediation Strategies and Design
Remediation Strategies and Design

Based on our risk assessment and practical approach to remediation, CGL is able to provide integrated solutions to remediation problems. Using pragmatic methodologies and cutting edge technologies, we work in conjunction with a number of specialist remediation contractors and suppliers, providing commercially viable solutions to ground-related issues.

Our solutions are innovative, adding value by addressing our client's risk within a site’s physical, commercial, social and environmental constraints.  We pride ourselves in employing staff  with a wide range of skills, including civil engineers and environmental specialists, which enables us to provide demonstrably sustainable solutions that are both buildable and appropriate in a construction site context.

When it comes to dealing with permitting issues, negotiating agreement with regulators, or supplying third party validation, our independence allows a satisfactory conclusion to be reached for all parties involved.  

CGL offers specialist support and management advice to move remediation solutions forward to implementation and completion.  We offer an overall project management service from dealing with contract preparation and the tendering process, through to site management, making sure that the project is delivered successfully. 

We are often approached for advice and action on emergency situations, when quick and technically robust solutions are needed to protect our clients against potential prosecution. Using robust remediation strategies and design, CGL is able to convert a potentially harmful contamination problem into an environmental success story.

For further information about Remediation Strategies and Design please contact Jo Strange at our Head Office on 01483 310600 or email Jo at JoS@cgl-uk.com.

Soil Gas Assessments and Design
Soil Gas Assessments and Design

As leading specialists in the assessment of soil gas and the design of protection measures for buildings and sensitive sites, CGL has extensive practical experience of numerous developments where soil gas has been an issue of concern to site owners, regulators and third parties.  We have also been instrumental in developing the procedures for protecting developments from gas risks through involvement of our staff in the formulation of national guidance and standards, including CIRIA C665 and BS8485.

CGL is appointed by a wide range of clients, from those considering site purchase and wanting to understand the scale of any existing soil gas issues, through to regulators requiring specialist expertise to assist in technical disputes over gas monitoring data interpretation or the suitability of protection measures for structures.  We provide advice and support regarding all aspects of ground-related risks with the scope of our advice covering such issues as:


  • Desk study assessments;
  • Design and implementation of monitoring programmes;
  • Quantitative risk assessments;
  • Design of gas protection measures;
  • Construction supervision and validation;
  • Post construction monitoring; and
  • Expert opinions.

The success of CGL’s assessments and designs is based on a sound understanding of the scientific principles of gas generation and migration, applying these principles to designs that are appropriate for installation, often within hostile site environments.  Our detailed knowledge and understanding of site conditions permits a risk-based approach that is specifically tailored to individual sites rather than the blanket approach often adopted within the industry.  Taking account of such site specific information may lead to considerable savings in cost and programme timings or gaining agreement with regulators.

CGL operates directly for clients, or in association with their design teams to initially determine whether a risk exists (often this can be easily engineered out at an early stage at little cost), and then, if a risk does exist, to provide a robust and cost-effective solution that can be readily incorporated into building structures.

For further information about Soil Gas Assessments and Design please contact Ian Marychurch at our Head Office on 01483 310600 or email at Ian at IanM@cgl-uk.com.

Unexploded Ordnance Risk Advice
Unexploded Ordnance Risk Advice

Tens of thousands of bombs were dropped on the UK during WWII; approximately 10 per cent of these did not detonate at the time and although many have been recovered and rendered safe, there are still a significant number left untouched after the war.

In recent years, senior staff at CGL have played a key role in raising awareness of such matters via various industry organisations, being closely involved in the publication of recent construction industry guidance on Unexploded Ordnance UXO (CIRIA Report C681, 2009).

UXO remains relatively benign if left undisturbed.  However, once intrusive investigations, excavations or earthworks are conducted in an affected area, the risk of contact with the UXO is increased.  And the responsibility to reduce or remove that threat usually lies with the landowner or developer.

When it comes to unexploded devices on development sites, it pays to tread carefully.  All will agree that there is an overriding need to mitigate risks to ensure safe site development.  This, however, should not be at the expense of unnecessary surveys and clearance services.

It would be unfortunate if you were to encounter an unexploded device on site; they are rare indeed, and the consequences of inadvertent detonation are potentially very severe.  The unpredictable and emotive nature of the perceived risks can play into the hands of overzealous risk managers and clearance operators which may lead to unnecessary risk mitigation and development costs.

At CGL, we consider it important to reflect on genuine risk reduction which is not always achieved by the expensive intrusive policy preferred by element of the industry as was highlighted in CIRIA C681.

We have been involved in a number of development projects on former military sites or heavily bombed urban areas, gaining considerable experience in assessing the risk of UXO and formulating development plans.  Working closely with reputable ordnance assessment risk management and clearance specialists, CGL have also overseen the safe clearance of ordnance from affected sites to allow unhindered redevelopment such as our work at the ex-MoD site at Bramley.

We believe that our pragmatic, informed and experienced approach to UXO provides appropriate risk assessment and mitigation without overstating the issue.

For further information about Unexploded Ordnance Risk Advice please contact Dan Matthews at our Head Office on 01483 310600 or email Dan at DanM@cgl-uk.com.

Waste Management and Minimisation
Waste Management and Minimisation

Increasing disposal costs and limited disposal facilities, together with the pressure on minimisation of virgin aggregate use, has meant waste management and minimisation now has a significant impact on project profitability, and even viability.

CGL has a proven track record in advising clients on the minimisation of waste volumes coupled with the ability to undertake on-site delineation, from site investigations and segregation supervision through to numerical modelling, ground profiling, and providing reliable excavation volume assessment prior to contractor site mobilisation.  Plans can be supplied for on-site use to minimise excavation timescales, and waste disposal can be minimised by ensuring appropriate re-use of site-won arisings.

CGL frequently assists clients in gaining appropriate permits, exemptions or declarations under the Development Industry Code of Practice.  This documentation is appropriate for either re-use on the site of origin, or more frequently on another local development site, providing a cost effective, sustainable solution for a number of participants.

As well as this, our staff are able to assist our clients with activities under the WRAP protocol for re-use of aggregates, reducing the burden on virgin materials and ultimately the costs associated with the development.

At CGL, we offer tailored one day training sessions covering the current waste management legislations and the potential opportunities and limitations associated with available options for material management.  These sessions are presented by two senior engineers registered as Qualified Persons for ICoP declarations.

For further information about Waste Management and Minimisation please contact Jo Strange at our Godalming Office on 01483 310600 or email Jo at Jos@cgl-uk.com.

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