Guidance for undertaking Desk Studies is provided by British Standard BS5930:2015 and BS10175:2013. The first stage of a Contamination or Geotechnical Investigation should always be a desk study (sometimes known as a ‘Phase One’ or ‘Desk Top Study’). This will provide information on the historical, environmental, geological, hydrogeological and hydrological site setting in order to establish likely contamination and geotechnical ground related risks for a site.

A Phase 1 Desk Study is a preliminary risk assessment for the collation and review of relevant information regarding the historical, geological and environmental data of a site. It is used to ensure proper planning of subsequent stages of a site investigation and development of a site.

The Phase 1 Desk Study will aim to identify any potential ground related hazards or contamination sources. It will also look at pathways and receptors which could pose a risk to human health, vegetation, wildlife, controlled water structures or associated services.

Investigations begin by looking at historical maps of the site and area and gathering environmental information. This type of information includes the former use of a site. Sites of interest would include historical landfills, factories, industrial land, manufacturing depots and agricultural land.

The Phase 1 Desk Study will normally include:

• Reviewing historical OS map data;

• Purchasing of a Landmark Envirocheck / Mining and Ground Stability report;

• Reviewing of online databases including British Geological Survey, Environment Agency, Radon, MAGIC and UXO;

• Production of preliminary conceptual site models;

• Producing preliminary assessments of contamination and geotechnical related risks;

• Providing recommendations for intrusive investigations, where required.

EMS Geotech’s Phase 1 Desktop Reports will include as a minimum:

An Executive Summary - summarising the findings of the report

All Relevant Site Details - to include site name, boundaries, usage, proposed usage & details of the walkover survey

Historical Appraisal – a review of historical site usage based on past structures, ordanance information and the surrounding area

Environmental Appraisal – This will include aspects such as flooding, hydrology, pollution history, landfill use, contamination sources and hydrogeology

Geological Appraisal – This may include factors such as artificial ground, superficial strata, bedrock, mining, geomorphology, natural ground subsidence etc

Conceptual Ground Model – This a preliminary risk assessment of potential ground related hazards and potential contamination sources. It also looks at their pathways and receptors where there could be potential risks to human health and other factors.

Site Investigation – any recommendations if required. These could include a Phase 2 Intrusive Investigation, Ground Gas Monitoring, Flood Risk or Contamination Investigation etc

If the Desk Top Study has been commissioned to satisfy planning conditions, your completed report must be submitted to your Local Authority Planning Department.

If the report has identified further investigations, for example a Phase 2 Site Investigation, EMS Geotech will be able to guide you through the process and undertake this on your behalf. More information regarding Phase 2 Site Investigations can be found here

If timescales are tight, and subsequent remedial action is thought to be likely, a Phase 1 Desk Study and a Phase 2 Site Investigation can be undertaken simultaneously.