Phase 1-4 Site Investigations

Phase 1 Site Investigation

Phase 1 Site Investigation or Preliminary Risk Assessment (Desk Studies) are an integral and founding part of the site investigation process.  They are used to create a preliminary Conceptual Site Model (CSM) in order to identify any potential pollutant linkages.  The CSM is then refined and conclusions and recommendations are provided.

The desk study process involves putting together a picture of a sites environmental setting by collating site specific data and information which includes the geology, hydrogeology, hydrology, site history, mining & quarrying, landfill & waste, and any regulatory concerns from statutory bodies such as the Local Authority and the Environment Agency. This allows our team of Environmental Consultants to build a picture of a site by identifying any potentially significant features such as potential contamination sources, pathways and receptors, and subsequent ‘pollutant linkage’; where all three must be present for a pollutant linkage to exist. If present, then further investigation would be required (see our page on Phase II Site Investigations).In addition to the above our Phase I Site Investigations also identify the anticipated ground conditions beneath any proposed buildings for geotechnical purposes.

Phase 2 Site Investigations

Phase 2 Site Investigations are the second stage in the site investigation process, where the results and recommendations presented in the Phase 1 Desk Study outline the requirement for further investigation. This is usually a ‘preliminary investigation’ by way of intrusive ground investigation using a combination of various techniques depending on the potential risks identified during the Phase 1 Desk Study. GeoCon are experts in ground investigations for all types of sites and projects including contaminated land, proposed roads, bridges and infrastructure, areas of former mining, areas of landfill and much more.

Phase 2 Site Investigation techniques include hand pitting, machine excavated trial pitting, window sampling and windowless sampling, cable percussion boreholes, rotary open boreholes and rotary cored boreholes. Each technique is used for different applications and a typical ground investigation may comprise a combination of the above techniques depending on factors such as sources / receptors, geology / hydrogeology and access constraints. The ideal Phase 2 Site Investigation would be designed to collect information on a site as a whole for both geoenvironmental and geotechnical purposes, this is the most cost effective as it reduces the potential for repeat investigation, during a site investigation samples would be collected for chemical testing and geotechnical testing.

Standard practice would be for one of our specialist engineering geologists to design the preliminary site investigation using targeted and non targeted methods to achieve a good overall coverage of the site and to target any potential sources. The results of this investigation would usually be enough to determine a sites suitability for use and in some cases may outline the requirement for further work or Phase 3 Site Investigation.

By undertaking a Phase 2 Preliminary Site Investigation, it allows us to keep costs down for our clients as most sites would not require a Phase 3 Detailed Site Investigation.

Phase 3 Site Investigation – Remediation

Remediation is the act of rendering a site ‘fit for purpose’ under the National Planning Policy Framework (NPPF). In its broadest definition, it’s taking previously developed land and making it suitable for redevelopment, in its many forms. The term remediation covers many activities and even more solutions and is generally only applicable in land development projects.
Here at GeoCon we specialise in a variety of remediation related services, but mainly that of chemical contaminants from site related sources or more what is more generally known as “contaminated land”.

Contamination remediation can range from the very basic: complying with the BRE cover system approach, to the more complicated, such as bioremediation; and can be achieved in a day or over several years depending on the size of the site and the approach adopted. We have a wealth of experience of remediation design, management and supervision; all the skills needed to support a project through the remediation process. Taking the findings of a site investigation GeoCon will consider the options available to break the pollutant linkages associated with a site and formulate a remediation strategy to achieve that requirement. Not only that but with our links throughout the sector we can advise on suitable remediation contactors, many of whom we have first hand experience of working with.

Not as extensive as remediation of contaminated soils, but just as important, is that of the remediation of contaminated controlled waters, either groundwater or surface waters. With the contamination of controlled waters being, by its very nature mobile, this poses a different approach to contaminated soil remediation. Again, our depth and breadth of experience puts GeoCon in an ideal place to design and manage remediation projects for controlled waters.

The final aspect of contaminated land associated remediation that we at GeoCon carry out is that of remediation of hazardous ground gases. Whilst we can advise on the building protection measures, we are not design engineers so it is important to appreciate we cannot design gas related building protection measures. Rather, in this scenario, we can advise on external gas control measures, such as: passive and active land venting systems; barriers and trenches; and active and passive gas collection systems.
Remediation of contaminated soils and controlled waters along with hazardous ground gas remediation would be handled here at GeoCon by our team of environmental consultants.

Phase 4 Site Investigation – Validation

Whilst remediation is the act of rendering a site ‘fit for purpose’ under the National Planning Policy Framework (NPPF), validation is the process by which the evidence is gathered and presented to verify that the proposed and agreed upon remediation strategy has been carried out. Here at GeoCon we specialise in a variety of validation related services, but mainly that of chemical contaminants from site related sources or more what is more generally known as “contaminated land”.

Validation, also known as Verification, is a reactive process and is difficult to predict the duration and extent of the involvement of the independent assessor, such as GeoCon.  On this basis, based on our experience, we offer our clients a budget based on anticipated workload and provide regular updates as to how the work / budget is progressing through the validation process.

For short term remediation projects such as adopting a BRE cover system, validation can even be carried out upon completion of the remedial activity.  The downside of this approach is that we would need to advance validation hand pits in the finished conditions and all the potential disturbance that would entail.

It is more usual to provide a ‘watching brief’ during the remedial work and report accordingly.

When dealing with a cover system remediation, none of this negates the need to confirm that any material brought onto site for use in soft landscaping areas (e.g. gardens) is, itself, also ‘fit for purpose’ and suitable for use in its intended location.  We would always need to collect validation samples for the imported material.

Validation of groundwater remediation is a long-term commitment, as generally, the processes adopted for groundwater remediation are long term in themselves.  Quite often validation of this process is achieved by showing a reduction in concentration of the Contaminant of Concern over time with a prediction of when full validation will be achieved, a process of monitored attenuation.


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