What is a Walkover Survey?

A walkover survey allows the assessor to identify visible signs of contamination at a site, in order to determine the potential risk to site users or to confirm the absence of such contamination. Walkover surveys are commonly be carried out as part of wider contaminated land risk assessments, and are often recommended by local authorities for contaminated land investigations produced to support planning applications or comply with planning conditions.

How to conduct a walkover survey? - In order to carry out a Phase 1 Preliminary Risk Assessment (desk study), the first phase of a contaminated land investigation, a walkover survey will usually be required to allow the assessor to identify visual or olfactory evidence of contamination on a site that would otherwise be impossible to identify without visiting the site. A walkover survey for a contaminated land investigation is a straightforward process that involves visiting a site to make observations of potential contamination sources and pathways.

As outlined in Environment Agency's Land Contamination: Risk Management guidelines, a site walkover should record information such as the:

• Current use and status of the site - occupied or vacant
• General condition of site and surrounding land use
• Presence of visual surface staining and odours
• Topography and surface condition - open ground, hardstanding and other geotechnical or surface features
• Local surface water features
• Ecology
• Presence and type of vegetation
• Presence and extent of any invasive plant species
• Buildings and below or above ground structures such as fuel tanks
• Above and likely below ground services
• Access and security

Conceptual Site Model - Once potential sources of contamination have been determined by the walkover survey, potential pathways are identified to assess the possibility of pollutant linkages being present. This will involve collecting information on the:

• Type, extent, location and behaviour of potential contaminants
• Information on site drainage and other man-made potential pollutant pathways
• Type of receptor you are dealing with - for example, human health, controlled waters, ecology or property
• Characteristics of the people and the environment potentially affected by the contaminants

Why Do I Need a Walkover Survey?

A desk study alone may not be able to identify contamination sources that aren't visible on maps and in photos, so these may go unnoticed. For example, rural sites are unlikely to be very detailed on a map and there may not be a lot of information available for the site in online databases, therefore, a walkover survey is necessary to identify site specific contamination risks.

Even small sites where contamination is not expected to be present a walkover survey will often be required in order to confirm the absence of contamination sources and confidently conclude a low level of risk. During a site investigation, a walkover survey can also allow the assessor to obtain anecdotal evidence of potential contamination at a site, from site owners, users or neighbours, which would otherwise be impossible to identify without visiting the site and talking to local residents or workers.

A walkover survey is an essential part of a contaminated land investigation, produced to support a planning application or comply with planning conditions. Contaminated land planning conditions on a decision notice are often shown as a phased process, with the first stage being a preliminary risk assessment (desk study) that will often require a supporting walkover survey to be accepted by the local authority.

Meet Our Contaminated Land Consultants

Consultants - Supervised by our Chief Technical Officer, Louis Turner, our fully comprehensive contamination walkover surveys, are carried out by highly qualified consultants, combining over 30 years experience with recognised in-depth technical qualifications in identification of contamination and environmental issues, as well as the implementation of remediation work.

Management - Our wealth of experience in project management, logistics and environmental consulting allows us to provide an efficient, friendly and high quality walkover survey service for our clients. As a company, we believe that helping clients achieve their goals while simultaneously protecting the environment is a true "win-win" situation.

Partners - Our experienced, professional and qualified construction and consulting partners further extend the range of environmental and land contamination services we are able to provide. Our partners provide our clients with services such as waste management, remediation implementation and construction services.

Contact Us - Contact us and let us know your requirements. We regularly carry out walkover surveys as part of contaminated land investigations for planning applications and due diligence. Following initial consultation we can provide an outline proposal detailing how we can help and the costs involved. Our environmental consultants will then carry out a walkover survey, as part of a wider contaminated land investigation, allowing you to stick to schedules and minimise any disruption to your project.

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