Phase I Desk Study

A Phase I investigation, also known as a desk study forms the basis of the preliminary risk assessment of potential geo-hazards. Undertaken at an early stage of the planning process, at the pre purchase or as part of a due diligence exercise a desk study can provide early recognition of potential problems, minimise the risk of unforeseen ground conditions and facilitate appropriate scoping of the later stages of the site investigation and present significant savings in the long terms.

Each desk study that we carry out is designed and assessed on a site by site basis. The desk study required for a new power station development would be significantly more complex than a desk study for a simple barn conversion. However, the same procedures would be followed and the level of risk based detail would be comparable.

A desk study contains a review of all of the information available about a site or parcel of land, including the following elements:

Review of Ordnance Survey current and historical mapping:

• geology
• hydrogeology
• hydrology
• local environment
• environmental incident data
• general environmental data

The sources of information may vary from site to site but the main sources may include:

• geological and hydrogeological maps and publications together with existing borehole data on or near the site
• historical maps and aerial photographs, local historical records
• review of owner/Client provided data
• anecdotal evidence
• consultation with Regulators - the Environment Agency, the Fire Service or land registry

Once the desk based data has been reviewed a site walkover will be undertaken.

The objective of Site Walkover survey is to complement the findings of the desk based data review.

At this point a qualified engineer visits the site in order to assess the following:

• topography of the site - indications of slope instability, spoil heaps or signs of ground subsidence
• geology - exposures of soils and rocks which can be examined and sampled
• surface water – water features, signs of flooding, springs, water-logging
• vegetation - signs of vegetation die-back as a result of contamination of the ground; presence of invasive species such as Japanese Knotweed or Giant Hogweed, trees which may cause shrinkage and swelling of clay soils
• ecology - indicators of protected species, newts, badgers, bats or nesting birds
• contamination - indications of spills, disturbed ground, areas of fill or spoil heaps, old fuel or oil tanks
• structures - settlement of existing structures or the use of asbestos, indicators of archaeological value
• local knowledge - anecdotal information on past uses of the site or past problems in the area
• access and information - such as access for site equipment and location of buried or overhead services.

Following on from the Site Walkover survey a preliminary risk assessment (Conceptual Site Model) based on 'source-pathway-receptor’ approach is undertaken.

At this stage our engineer will be able to advice on economic design of the proposed buildings, construction or remedial works and any liabilities with regards to contamination or other complications relating to protected species of ecology.

Professionally undertaken Desk Studies will be immeasurably beneficial both to budget and programme of your project.

What can you expect from our Desk Studies?

• professional expertise
• quick turnaround (we are able to prepare a Desk Study within 3 to 5 working days)
• free support on submission to Regulators and advice on further steps that will enable you to plan your budget and time scale.

Please, go to Phase II Site Investigations, if you would like to find out more.

What do you need to do?

Provide us with the following information: site location, size, current and proposed use. Any plans/drawings of the site will be beneficial.

What happens next?

Please contact us on 01603 298 076 or paul.davies@geosphere-environmental.co.uk

You will usually receive the quotation for the desk study on the same day. A consultant will be assigned to your project and then order any information that is required to undertake the desk study for you. Once your data has been ordered and has been received it will be reviewed by the Consultant.

A site walkover will then be undertaken by the Consultant, who will then produce the desk study report for you. The total time for a desk study for a small to medium sized site will be five working days from instruction to receipt of your desk study report.

Liaison with Regulatory bodies if required will be carried out free of charge.

It should be considered that a good quality desk study could save significant amounts of time and money during the course of a site purchase or development. Desk studies are a requirement under PPS23 and failure to undertake them at the correct time can be a costly error.