Guidance

Using MCERTS for the chemical testing of soil

Published 30 April 2021

Applies to England

How to provide chemical test data for potentially contaminated soils or landspreading regulated under the environmental permitting regulations.

Sites regulated by the Environment Agency must use laboratories accredited to our Monitoring Certification Scheme (MCERTS). These laboratories will follow the MCERTS: performance standard for laboratories undertaking chemical testing of soil.

1. MCERTS explained

Using MCERTS will make sure you:

• meet regulatory requirements
• provide reliable, defensible and consistent test data
• provide assurance to all stakeholders such as industrial process operators, consultants, laboratories, other regulators and members of the public

We need to be sure of the quality of the analytical results we receive so we can make important regulatory decisions with confidence.

Analytical measurements always have random and systematic errors. These can vary significantly between laboratories. MCERTS sets error limits and ensures a consistent procedure for estimating errors.

ISO 17025 General requirements for the competence of testing and calibration laboratories gives requirements in general terms. The MCERTS performance standard gives extra guidance on specific applications like the chemical testing of soils. We worked with the United Kingdom Accreditation Service (UKAS) and industry to produce this specific application.

Find an MCERTS accredited laboratory.

2. Accredited test methods

Soil has a complex matrix that presents many challenges to analytical chemists. A test method that will work on a sandy soil may not work well on a clay soil. You will only receive MCERTS accredited results if a test method has been shown to work on your soil samples. In most cases we will only accept results from testing methods accredited to the MCERTS standard.

Laboratories can be a fixed or mobile site. They include organisations that take samples and carry out on-site testing using portable instruments.

Laboratories can accredit test methods that use portable instruments if the test methods meet MCERTS requirements.

We may agree you can use on-site testing methods that are not MCERTS accredited as part of a site investigation if you can provide evidence of quality management to your regulatory officer. This includes:

• document control and record keeping
• training
• standard operating procedures and a sampling plan
• quality assurance (which may include parallel testing of a proportion of samples in an MCERTS laboratory)
• equipment maintenance
• auditing

3. What you must check

You must:

• make sure (where appropriate) that chemical analysis results you submit to us conform to MCERTS requirements
• check whether the laboratory carrying out the analysis has MCERTS accreditation for all the parameters requested
• check that the testing methods used by the laboratory are appropriate for the parameter, critical level of interest and soil matrix

The critical level of interest is the value around which a decision is required, for example it may be a soil guideline value, a regulatory limit, or some other concentration of importance. We need to know whether a concentration determined is above or below that value.

The critical level of interest may also be the range of concentrations of a parameter expected, or usually determined or observed, in a series of samples.

If the laboratory does not have accreditation for all the parameters they must sub-contract the non-accredited parameters to a laboratory that has the MCERTS accreditation. If you cannot find a suitable laboratory then contact us for advice.

You must make sure there is a complete audit trail of samples. Do this by working with the laboratory and reporting all relevant information. Include:

• the location of the sample, including depth where necessary
• the unique sample code or reference
• the date and time the sample was taken
• the name of the laboratory, including the subcontracting laboratory where necessary
• the date the sample analysis was completed
• the parameter analysed – state if the sample was preserved or stabilised on site
• if the analysis was carried out on a dried or as submitted basis
• results of the analysis – this must be on a dry-weight basis
• any other relevant comments, for example, visual characteristics of the sample

4. What the laboratory will do

The laboratory will:

• make sure they understand and document your requirements and that the test methods they use will meet these requirements
• select and validate the test methods
• meet our set MCERTS performance standards for method precision and bias
• establish performance characteristics to make sure that analytical procedures are correct
• where available, use certified reference materials of appropriate matrices to test methods
• record and report details of sample pre-treatment, such as crushing or grinding, sieving, preservation or constituents removed (for example, stones)
• keep the primary data for 6 years

5. Sampling

The MCERTS: performance standard for laboratories undertaking chemical testing of soil does not cover sampling. You must:

• make sure that you use appropriate sampling procedures, preservation and transportation to minimise the loss of parameters
• make sure sampling procedures are suitable for the test methods used by the laboratory
• record the sampling method used

For guidance on sampling see:

• the references given in the intrusive site investigation section of our Land contamination: risk management guidance
• site characterisation (INFO-SC) on the CL:AIRE Water and Land Library

You can also use BS 10175 Investigation of potentially contaminated sites. Code of practice – you will need to buy this.

6. Contact us

Contact the Environment Agency if you want more information about MCERTS.

General enquiries

National Customer Contact Centre
PO Box 544
Rotherham
S60 1BY

Email enquiries@environment-agency.gov.uk

Telephone 03708 506 506

Telephone from outside the UK (Monday to Friday, 8am to 6pm GMT) +44 (0) 114 282 5312

Monday to Friday, 8am to 6pm.