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Past economic activities have left the UK with a substantial legacy of land which is contaminated, for example by past industrial, mining and waste disposal facilities. Unless adequately addressed, this contamination can pose unacceptable risks to both people and the environment.

Although standards in the land contamination sector have improved greatly over the last two decades it is acknowledged that the quality of gas protection installation and verification work remains variable. Thus, installers and verifiers came together to develop this accreditation scheme to improve the quality of gas protection verification and increase the knowledge of staff involved in this industry.

Raising the quality of gas protection installation and verification will result in economic benefits by ‘getting it right first time’ avoiding time consuming repairs that are the consequence of poor installation or poor understanding of follow on contractors that can result in damage to gas protection systems.

This scheme also helps demonstrate to a Suitably Qualified Person (SQP) under the National Quality Mark Scheme (NQMS) for land contamination management, that the gas protection verification work has been undertaken by competent personnel.

Overview and Objectives of the Scheme

This scheme seeks to raise standards in membrane inspection, verification and reporting and provide all stakeholders involved in land contamination management with enough confidence that risks associated with ground gases have been adequately managed.  

This scheme does not specifically address damage of membranes from follow on trades as this is outside the remit of the scheme, however, risk of damage to installations is considered as part of the verification process and management procedures. Failures of membranes and repairs to the membrane remain the responsibility and liability of the membrane installing contractor and not with the verifier.

The scheme applies to both the practical installation of the gas mitigation measures and to the verification reporting process. Thus, recognising different personnel often undertake the installation work to the reporting, there are two separate accreditation routes to demonstrate competence in the installation and the verification design, preparation of method statements and verification reporting. The two levels of accreditation available are: ‘Technician’ and ‘Specialist’:

  • Technician level of accreditation (TGPV) is intended for field technicians who confine their work to inspections and do not prepare verification design or method statements (although they will follow ones prepared by others) and do not prepare validation reports (although they do prepare field records that form part of the validation report)
  • Specialist level of accreditation (SGPV) applies to those involved in the whole range of gas protection verification including design of the verification, preparation of method statements, inspections and preparation of validation reports.

The competencies required for each accreditation route are detailed in Table 2 and are split into two categories; knowledge and understanding and the practical skills.

The objective of the Gas Protection Verification Scheme (GPVS) is to ensure that the gas protection verification part of land contamination management meets the necessary technical and regulatory standards. The specific aims of the scheme are to:

  1. Increase the knowledge of gas mitigation verification across the industry
  2. Provide a list of competent individuals who prepare method statements, undertake the inspection of gas protection measures and prepare the validation reports
  3. Complement the NQMS by providing a process by which competency in gas protection verification can be demonstrated.

The scheme is voluntary and thus the procedure is simple, and costs will be kept as low as possible (but enough to cover its running costs including auditing). It has been designed to operate alongside and within existing quality management schemes such as the NQMS. Competencies of individuals can be demonstrated in several ways such as if people are in possession of the NVQ Level 4 Diploma in Verification of Ground Gas Protection Systems that has been designed by the British Verification Council and administered by the Property Care Association. This qualification will be recognised against a number of the key practical competencies that are required. Alternatively, people will be able to demonstrate their competencies through demonstration of experience.

The scheme is an accreditation scheme for individuals and does not apply to companies. 

Roles and Responsibilities of the Scheme

Table 1 presents the roles and responsibilities for those involved in the scheme:

  • Scheme Administrator - CL:AIRE
  • Accredited Person - Technician 
  • Accredited Person - Specialist

Table 1: Roles and responsibilities



Scheme administrator – CL:AIRE

Responsible for administering the accreditation scheme,directly maintaining the records of who has achieved each accreditation level, maintaining an up to date register of accredited practitioners and copies of declaration certificates.  In addition, CL:AIRE will administer the audit and complaints process from which the scheme can be improved periodically. CL:AIRE does not directly manage or supervise accredited practitioners under the scheme.

Accredited person – technician 

Responsible for undertaking gas protection verification safely, diligently and with professionalism (eg in accordance with the verification plan and method statement, knowing when to ask for assistance and providing advice on how to inhibit damage to gas protection systems during follow up works). 

Accredited person – specialist 

In addition to the responsibility for a technician level of accreditation, the specialist registration also is responsible for data interpretation, preparation of the verification strategy, method statements and validation reports in accordance with current industry guidance. The Specialist is also responsible for sign-off on the GPVS Declaration. See Stage 5 - Applying for a Declaration of Compliance on the Operation of GPV page.

Accredited practitioners do not work for or on behalf of CL:AIRE and, as such, CL:AIRE is not responsible for installation or verification at any individual site. CL:AIRE has no technical input to any individual installation or verification.

Applicability of the Gas Protection Verification Accreditation Scheme

The scheme is applicable for use within the Town and Country Planning and Building Control regimes primarily, although would also be of use in other circumstances where demonstrating competency is important, for example if properties require retrofitting or to support potential claims.

Operation of the Gas Protection Verification Accreditation Scheme

The scheme aims to improve practitioners’ skills and competencies in gas protection verification and the preparation of gas protection verification reports. A report produced by an accredited practitioner under the scheme will be accompanied by a "declaration of compliance" and will bear the Gas Protection Verification Scheme “Quality Mark” logo so it can be clearly identified.

The Gas Protection Verification Accreditation Scheme process is as follows:

  • Stage 1 – Eligibility Criteria of Practitioners
  • Stage 2 – Application Process of Accreditation (Technician & Specialist)
  • Stage 3 – Assuring the quality of the work on site
  • Stage 4 – Preparation of the Verification Report
  • Stage 5 – Applying a declaration of compliance
  • Stage 6 – Process Review
Stage 1 – Eligibility Criteria of Practitioners

Table 2 specifies the core competency requirements for people applying for entry to the CL:AIRE register of gas protection verifiers via the technician and specialist levels. Once a candidate can demonstrate that they meet these requirements they can apply to be assessed. It is noted that those in possession of the NVQ Level 4 Diploma in Verification of Ground Gas Protection Systems will already have been tested against the core competencies required at technician levels.  Therefore, these candidates will be able to go straight to the stage 2 application process.  

If candidates can demonstrate competencies through the possession of appropriate skills cards eg construction skills council site safety cards etc, these competencies will be taken into consideration and not be further tested at stage 1.

Table 2: Core competencies

What is GPV Accreditation?

Technician level of accreditation (TGPV)

Intended for field technicians who confine their work to inspections and do not prepare verification design or method statements (although they will follow ones prepared by others) and do not prepare verification reports (although they do prepare field records that form part of the verification report. 

Specialist level of accreditation (SGPV)

Applies to those involved in the whole range of gas protection verification including design of the verification, preparation of method statements, inspections and verification reports.

The competencies required are as follows:

Appendix 1: Assessment Criteria   

All candidates who are applying for SGPV or TGPV must show that they are competent with respect to the following criteria as outlined in the GPV scheme document.  



Stage 2 – Application Process of Accreditation

There are two stages to the application process for the technician and specialist levels of accreditation.

  1. Submission by the applicant and checking of the application by the scheme administrator
  2. Interview — knowledge & practical experience

The stages are summarised in the flowchart in Becoming an Accredited Person.


Once an individual has been approved, they will be eligible to be added to the register of competent accredited individuals.  SGPV and TGPV levels will be required to abide by the Code of Conduct. They will be assigned a unique registration number which, in the case of SGPVs, must be used on all declarations.   On the register of approved competent individuals (SGPV Register), their name will be stated along with the company that they work for.  If individuals move companies, they will be expected to keep their contact details up to date on the CL:AIRE website.

Designated award title:

TGPV – Technician in Gas Protection Verification

SGPV – Specialist in Gas Protection Verification

A certificate will be issued to each accredited individual which will be renewed every four years.

Fees and Refunds

There are two fees involved in the accreditation scheme:

  • An application fee which is required to cover the costs of administration and the review of applications. This fee applies for each application including where previous applications have been refused or deferred.  As a not-for-profit organisation, CL:AIRE aims to ensure this fee reflects only necessary expenses involved in the administration and review of applications.
  • An annual register maintenance fee for SGPV level is required to cover continual scheme administration costs.

Refund Policy: As the application fees are to cover administration costs, no refunds are eligible once the application has been processed.  If the candidate voluntarily decides to not proceed following an application, the candidate must notify CL:AIRE as soon as reasonably possible.  It will be at CL:AIRE’s discretion if a full refund is provided minus a £95 + VAT administration fee.  The candidate will not be eligible to any refund if the candidate does not inform CL:AIRE in enough time to prevent the assessors starting their review.

The fee structure will be:

Application for Technician Level and Specialist Level – £249.00 + VAT

Annual Register Maintenance Fee (SGPV only) - £100.00 + VAT

If the applicant is unsuccessful at the interview stage, they will be informed as to the reason their application was unsuccessful.  If the applicant wishes to appeal, they must do this in writing.  A fee of £95.00 + VAT will be charged if the applicant wishes to apply for re-assessment.

Maintaining Registration and Revalidation

Annually, a fee will be paid to remain on SGPV Register.  On renewal, SGPVs will self-certify that they are maintaining their standards and keeping up to date with changes in industry practice in relation to gas membrane verification.  This will be captured via an online Continuing Professional Development (CPD) recording system in line with other professional organisation accreditation schemes.  Activities that should be recorded for CPD include courses and training attended (inhouse and externally), articles read, peer mentoring, acting as an assessor and preparation of validation reports.

In the event that the annual register maintenance fee has not been paid by the due date, the administrator of the scheme reserves the right to take the following actions:

  • Suspension and temporary removal off the Register until full payment is made
  • After six months overdue – revocation of registration. Re-entry to the register would only be possible by new application.
Revalidation Registration

Every four years, all accredited personnel (SGPVs and TGPVs) will be required to sit and pass (by 80%) an online test to ensure competency is maintained. Individuals that fail the online test will be called for interview and further assessment, and training may be required.  The administrator will report all failures and the scheme reserves the right to remove those individuals from the register. 

Where individuals fail to revalidate their registration by the required date, CL:AIRE reserves the right to take the following action:

  • After three month – suspension and temporary removal off the register until the test is undertaken
  • After six months – revocation of registration and removal from the register. Re-entry to the register would only be possible by new application.
Stage 3 – Assuring the Quality of Work on Site

Accredited personnel will assure themselves that the quality of workmanship is in accordance with current standards to BS 8485: 2015+ A1 2019 and CIRIA 735 and a suitable inspection record is prepared. An example template of site record is available in Appendix 2.

Stage 4 – Preparation of the Validation Report

The validation report that demonstrates the effectiveness of the gas protection measures, is produced in accordance with current standards.

Stage 5 – Applying a declaration of compliance

If a SGPV wishes to prepare a validation report in line with the Gas Protection Verification Scheme, they will be required to purchase a standalone declaration in order to be able to apply the “Quality Mark”.  The Declaration will be available to purchase online on the Gas Verification Accreditation Scheme website.  The fee per Declaration is £95 + VAT.  Quantity discounts are available on application.

Once paid for, the Declaration will be available to be downloaded and appended to the validation report.  Each certificate will have a unique reference number.  The unique reference number will be publicly available for viewing on the register of accredited personnel as each unique number will be assigned against the accredited person’s name. Each accredited person will be required to create an account on CL:AIRE’s website to allow tracking of the "declaration of compliance" and to assist with auditing.  A single declaration will be purchased per validation report, with a separate declaration for residential, commercial/retail, education or healthcare sites.  A residential declaration may cover up to a maximum of 50 plots. 

CL:AIRE will maintain a record of all declarations bearing the “Quality Mark”.  Each declaration will have a unique reference number and will be linked to an individual accredited person. The Declaration will gather the following information:

  • Site Name
  • Site Address
  • GPVS Declaration Reference
  • Site Type & Plot Number
  • Verification Report Title
  • Verification Report Identifier
  • Clients Name
  • Name of Accredited Person
  • Accreditation Number
  • Contact Details
  • Company Name
  • Completed declaration
  • Signature *
  • Date

*The Declaration is manually signed by the SGPV after the completed PDF is downloaded.  The final declaration is required to be scanned and appended to the front of the validation report it is supporting.

The purpose of the declaration of compliance is to provide assurances to the client that the validation report has been prepared in accordance with industry standards and prepared by an accredited person.

The declaration does not hold the same status as formal certification of construction under Building Act 1984 (England & Wales) and Building (Scotland) Act 2003.

Go to Purchasing a GPVS Declaration for further details.

Stage 6 – Process Review

The accreditation scheme is designed to improve the competency of personnel and the quality of verification and validation reporting preparation for gas protection. Companies offering Gas Protection Verification Services (and the individuals they employ) do so with the benefit of appropriate insurance (eg public and professional indemnity insurance).  Liability for reports (and any advice they may contain) remains with the producing company or individuals.

In order to ensure standards are maintained, CL:AIRE will ensure that both proactive and reactive mechanisms are in place to capture feedback with the aim of ensuring that the scheme objectives are met and continually improve over time. Feedback mechanisms and scheme auditing will be in place, including a range of sanctions available for non-compliance. See Appendix 3 for further details.

Communication with Key Stakeholders

CL:AIRE has developed this scheme with the support of a working group who work in the gas protection industry across the UK striving to improve standards.  Dialogue is open with all regulators, industry groups/trade associations across the whole UK - England, Scotland, Wales and Northern Ireland, with the hope that in time the scheme is endorsed and used by all.

Assessor Selection

For the scheme to be a success, a team of highly experienced accredited Assessors has been created.  All Assessors have been required to go through the same application process as those individuals applying for Specialist Level to ensure transparency, impartiality and objectivity.

CL:AIRE will actively encourage those individuals who are successful in selection as SGPV to become an Assessor themselves to join and grow the scheme. The scheme will try and select a wide range of Assessors from different geographic areas.

A list of approved Assessors is available here.

Appendix 1: Application Process

The first application window is now closed. We will be accepting new Applications for TGPV and SGPV from 1 July to 31 August 2024.
Please prepare your documents as listed under the GPVS Application Steps (to the bottom right of your screen). If you have any questions, please raise a ticket through the Help Desk.

This is an outline of the process to apply for TGPV or SGPV verifier status under the GPVS Accreditation Scheme.

To become an accredited gas protection verifier you will need to apply and follow these steps:

  1. Read Overview of GPVS Scheme
  2. Review the technical skills and competencies required for the Specialist in Gas Protection Verification (SGPV) and Technician in Gas Protection Verification (TGPV) and decide which is appropriate for you and that you would like to apply for.
  3. Compile the evidence for your application.
  4. Register and login to the CL:AIRE website, fill in the online application, upload the supporting documentation and pay the application fee.

Please navigate through the process using the secondary menu on the right hand side. All steps are listed under GPVS Application Steps.

Following your application, you will need to wait to hear back from CL:AIRE regarding your application status, and whether you have been invited to attend an interview.

If you are invited to interview, you will be asked to schedule and attend an interview with the Assessors. This interview will be conducted via video conference which will be recorded. 

The Assessors will advise CL:AIRE of their final decision regarding your application and you will then be provided with your results - either approval as a TGPV or a SGPV registered person, or feedback regarding the areas you need to improve in order to be approved.

Mentoring/Application questions

Should you have any queries regarding your application, or wish to ask for advice on the evidence you are submitting, please register with the CL:AIRE website (free), contact the CL:AIRE Help desk, go to “New Help Request” and select “Gas Protection Verification Accreditation Scheme” with the details of your enquiry.


Copied with permission from Appendix A5 CIRIA C735 – H. Mallett; L. Cox (nee Taffel-Andureau); S. Wilson; M. Corban, 2014. Good Practice on the Testing and Verification of Protection Systems for Buildings Against Hazardous Ground Gases, CIRIA, C735, London.

 Visual Inspection of Gas Protection Measures

Visual Inspection of Gas Protection Measures page 1

All feedback regarding the adequacy of individual quality marked reports, operation of the scheme or whether it concerns the performance of an individual will be initially investigated by CL:AIRE. Feedback should be provided using the feedback form:

If the feedback concerns the performance of an individual the complaints procedure will be followed:

As the scheme develops auditing of the process will be undertaken on an annual basis.

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