If you are about to buy, sell, or re-finance a property, or if you are applying for planning permission, you will need to know if your land is contaminated. The first stage in the process is making a site search.

The site search must be completed during the due diligence process, which is usually undertaken by a solicitor or conveyancer, who will check the details against a database. The search will list all recorded uses of the site and neighbouring areas (usually within 250 m of the property).

Approximately 5% of all UK site searches reveal that the property is on or near land once used for industrial activities. If your site is on or near an old industrial site, you will need a contaminated land assessment.

The phased approach to risk management used in the UK makes this a complex process. To guide you through the maze of regulation below is a simplified two-step process to understanding parts of the legislation surrounding contaminated land.

Step 1: Check with the Local Authority and Environment Agency.

As the statutory regulators of contaminated land issues, the Local Authority and Environmental Agency’s views on the site are the most important. They are able to determine if the property is acceptable or if further assessment is required. If the Local Authority has no concerns over contamination on your land, then you need not take any further action.

If there are concerns with the site the Local Authority will be able to guide you on what to do next. If the land is contaminated to the extent that it may be affecting groundwater or surface water, the Environment Agency must be contacted as they regulate the water environment and they will also provide guidance.

Step 2: Risk Assessment

If the regulators cannot discount the contamination issues the next step is to conduct a risk assessment as required under the Environmental Protection Act 1990. This step must be completed using a qualified contaminated land consultant or practitioner. The risk assessment process is divided into three phases.

In Phase 1 your consultant will interpret the information obtained from the site searches and other publicly available information such as geological and hydrological maps. They will also conduct a site walkover to gain an on-the-ground understanding of the area. From this information they will develop a conceptual site model (CSM) and complete a qualitative risk assessment (QRA) in accordance with UK guidance. If the QRA demonstrates low risks then no actions are required. If the QRA indicates medium or high risks then a Phase 2 contamination assessment is required.

The Phase 2 assessment involves physical sampling of the soil to confirm the level of contaminants. These results are compared against UK soil and groundwater thresholds (Generic Assessment Criteria or GAC) to determine if the land is contaminated and the extent to which it poses a risk. If the site is contaminated, remediation will be required. This is Phase 3.

Your consultant will agree a Phase 3 remediation scheme with the Local Authority and can oversee and report on the progress of the scheme. They can also manage the whole process on your behalf.

The relevant guidance documents for housing are DEFRA & Environment Agency (2004) Model Procedures for the Management of Land Contamination and NHBC & CEIH (2008) Guidance for the Safe Development of Housing on Land Affected by Contamination.

By Lela

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