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Certify Your Clean Cover System

The NHBC has released clear guidance on its requirements for the certification of any clean cover system. We would encourage any developer working towards the certificate to bear in mind the new guidance, but not to forget the requirements of other regulators too.

Cover systems are often used on sites with moderate to low levels of relatively immobile contamination, which commonly includes heavy metals and PAHs in shallow soils. The cover system is applied as a layer above the contaminated soil to keep people and vegetation from coming into contact with the soil.

Cover systems are widely used, as they are often seen as an “easy” way to deal with many lightly contaminated sites. However, there has been little guidance and direction when it comes to justifying and validating these systems, therefore the NHBC guidance is well placed to provide an approach.

However, it is worth considering what the opinion of other regulators may be before applying the cover system to a site. Cover systems are often prescribed on the basis of a BRE publication “Cover Systems for Land Regeneration”. Many Local Authorities will not accept this publication due to the assumptions it makes. It is therefore likely that they will also not accept the NHBC approach either.

At agb Environmental, we work with developers to ensure that any remediation scheme we develop meets the needs of all of the regulators involved. This includes giving consideration to what validation may be required.

Managing Director, Alex Brearley states: “We would always check with our clients if an NHBC warranty is required, and ensure that we meet this standard, but we would also want to ensure that we can meet the requirements of any other regulators with an interest in the site. This may include the water company, Environment Agency or the Local Authority.

“We have been asked to assist on schemes where a developer has imported soil without first checking that it has been certified clean. In many cases, this has resulted in a removal of the cover system and replacement with certified clean soil. Identification of a suitable source of material for the cover system is therefore essential.”

The NHBC approach identifies how cover systems should be validated, and provides a basis for the method to and frequency of sampling. This includes separating out any top and subsoil elements to the cover system.

agb Environmental has significant experience of undertaking the sampling and testing required to meet the HNBC standard, and has the understanding to mesh the NHBC requirements with those of other regulators.

For further information and to discussion contamination, land remediation, regulatory requirements and clean cover systems, please contact Alex Brearley on 01638 663226 or email

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