Construction quality assurance (CQA)

How to create a CQA plan, the CQA qualification requirements you need to meet and how to create a validation report.

You must have construction quality assurance (CQA) for the construction of all aspects of landfill engineering and infrastructure.

Landfill engineering

Landfill engineering includes:

  • permanent geophysical leak location system
  • leak detection layer
  • groundwater underdrainage system
  • sub-grade or formation layer
  • barriers
  • liners
  • liner protection
  • leachate collection system
  • leachate abstraction system
  • separation bund or layer
  • cell or area surface water drainage system
  • side wall subgrade or formation layer
  • sidewall containment and leachate collection systems

Landfill infrastructure

Landfill infrastructure includes:

  • permanent capping
  • temporary capping – such as engineered temporary caps, not cover materials
  • leachate abstraction systems
  • leachate transfer, treatment and storage systems
  • surface water drainage systems
  • leachate monitoring wells
  • groundwater monitoring boreholes
  • landfill gas monitoring boreholes
  • landfill gas management systems – including gas extraction wells, gas collection pipework and condensate management systems
  • lining within the installation

Construction quality assurance (CQA) plan

You must have a CQA plan. This is a written management system for any construction you propose.

What to include in your CQA plan

Your CQA plan must include the following information that is relevant to your site:

  • a detailed design description with reference to existing stability assessments
  • drawings of your proposed landfill engineering or infrastructure
  • specification of the proposed materials you will use to construct the landfill engineering or infrastructure – including the type and frequency of conformance testing
  • pass or fail criteria for all the materials you will use to construct the landfill engineering or infrastructure
  • details of the conformance testing you will carry out
  • how you will install each layer
  • CQA procedures for each layer
  • the procedure for agreeing changes to the design
  • details of the measures you will take where any non-compliance with the specification is identified – for each material you will use
  • details of the information you will include in the validation report

Your detailed design description must consider scenarios during and after construction, as well as after completing the filling and capping of the cell. If the design differs to that supported by a previously agreed stability assessment, you must provide a further stability assessment.

Where you need to carry out testing, you must use an independent laboratory that has United Kingdom Accreditation Service (UKAS) accreditation for each of the tests proposed.

All drawings, maps or plans must be to a recognised scale and all units must be metric. Each drawing should have a label that includes:

  • title of the drawing
  • installation name
  • name and address of the operator
  • date the drawing was made
  • drawing identification number
  • scale of the drawing
  • key
  • National Grid lines and north point
  • paper size of original drawing

The drawings of your proposed landfill engineering or infrastructure must, where applicable, show:

  • existing topography
  • location of proposed cell or capping works, including location of adjacent cells or caps
  • cell formation level, including under drainage system
  • level to top of geological barrier
  • level to top of leachate drainage and collection system
  • layout of leachate drainage and collection system
  • location of leachate collection, extraction and monitoring infrastructure, including the location of all target pads
  • location of gas collection and monitoring infrastructure
  • cross section of the cell lining system or infrastructure, including anchor trenches and under drainage system
  • cross section of cell perimeter and inter bund design, including connection with adjacent and existing cells
  • cross section of leachate extraction infrastructure and basal and sidewall pipework
  • cross section of leachate monitoring chamber
  • proposed waste thicknesses

You must record all levels in mAOD (metres above ordnance datum).

Submit your plan

You must submit your CQA plan to the Environment Agency. You must not begin constructing any new part of the landfill or landfill infrastructure until the Environment Agency has confirmed it’s satisfied with your proposals.

You must submit CQA plans sufficiently in advance of the programmed work to allow the Environment Agency to consider your proposals

The CQA plan must be signed by someone with a minimum route A qualification for a CQA engineer.

You or your CQA engineer or inspector must notify the Environment Agency of non-conformances against the approved CQA plan.

Environment Agency staff will visit the site during construction to monitor how you implement the CQA plan.

Update on progress and agree changes to your plan

Your CQA engineer or inspector must provide a progress update to your local Environment Agency office. They must normally do this weekly. Include:

  • progress in the last week
  • the proposed work programme for the following week
  • weather conditions
  • in the case of multiple clay sources, the sources currently in use
  • any testing carried out, with results recorded on the appropriate forms as listed in the CQA plan
  • any problems with proposed or agreed solutions

If the next and subsequent cells are the same design, you only need to submit a new cell layout drawing to the Environment Agency before construction. The Environment Agency will need to confirm it’s satisfied with the cell layout drawing and that it does not need any more information.

You must agree any change to the approved design in writing with the Environment Agency.

CQA personnel qualifications and experience

You must use competent people and resources in all aspects of your landfill engineering and infrastructure works. For example, use a competent contractor, who has experience of working with the materials you propose in your design, to carry out the works.

You must:

  • provide the Environment Agency with the CVs of all office and site based CQA personnel involved in the construction works, for agreement, before the works begin
  • outline the roles and responsibilities of each member of the CQA team within a CQA plan for the works

The Environment Agency will base its agreement on the following:

  • qualifications and experience of the proposed CQA inspector
  • evidence of continued suitability
  • complexity of the proposed works

Where, during the works, there is evidence of poor performance, the Environment Agency may remove their agreement.

You must provide the CVs of all office and site-based personnel involved in the construction works to your local Environment Agency officer a minimum of 5 working days before the start of the works. You must confirm what role they will perform.

You must make sure that each CV includes:

  • the name of the person
  • their proposed role
  • their education and qualifications
  • their site specific experience, including the:
    • name of the site
    • nature of the works
    • dates
    • role

Evidence of any mentoring and close supervision received, including the name and location of the site and type of work carried out, must be included in the CV.

Where mentoring and close supervision is to be provided for the proposed works, this must be agreed with your local Environment Agency officer. Details of all mentoring and close supervision carried out must be included within the validation report.

CQA engineers and inspectors must have at least route A or route B qualifications. You must confirm how your CQA engineer or inspector meets these requirements.

You must have third party CQA to make sure the materials and workmanship for the construction of all landfill engineering and infrastructure meets the standards specified in your permit and CQA plan.

All personnel involved in the CQA procedures must be independent of the permit holder and financially independent of the construction contractor.

The Environment Agency will accept large companies and sole traders as CQA engineers and inspectors. Operators must check that they have sufficient professional indemnity and public liability insurance, and are sufficiently independent.

Landfills for hazardous and non-hazardous waste

Where the proposed works are to be carried out at a landfill for hazardous or non-hazardous waste, the following will apply.

CQA engineer

CQA engineers must normally have either of the following route A or route B qualifications.

Route A includes all of the following:

  • a chartered engineer or chartered geologist
  • a minimum of 4 years’ design or supervision of landfill construction, which must include earthworks, clay liner and geosynthetics where construction includes these materials
  • a minimum of 2 years’ experience in the design, supervision or construction of landfill infrastructure, where applicable

Route B includes all of the following:

  • a minimum formal qualification in science or engineering, for example Ordinary National Diploma (OND), Ordinary National Certificate (ONC) or higher in civil engineering, mining engineering, engineering geology, building, quantity surveying or science with training in soil mechanics
  • a minimum of 8 years’ design or supervision of landfill construction, which must include earthworks, clay liner and geosynthetics where construction includes these materials
  • a minimum of 2 years’ experience in the design, supervision or construction of landfill infrastructure, where applicable

CQA inspector

CQA inspectors for earthworks and clay liner construction must meet either of the following route A or route B qualifications and experience unless agreed in writing with the Environment Agency.

Route A includes both of the following:

  • a minimum of 2 years’ continuous supervision of earthworks and clay liner construction on a landfill contract or similar experience
  • a minimum of one month, one-to-one close proximity training as an assistant to an experienced CQA inspector during earthworks and clay liner construction on a landfill contract, followed by mentoring and close supervision by the CQA engineer during the earthworks and clay liner construction works

Route B includes both of the following:

  • a minimum formal qualification in science or engineering, for example OND, ONC or higher in civil engineering, mining engineering, engineering geology, building, quantity surveying or science with training in soil mechanics
  • a minimum of one month, one-to-one close proximity training as an assistant to an experienced CQA inspector with relevant experience during earthworks and clay liner construction on a landfill contract, followed by mentoring and close supervision by the CQA engineer during the earthworks and clay liner construction works

Where construction includes geosynthetic elements, a CQA inspector must also meet both of the following, unless agreed in writing with the Environment Agency:

  • be able to understand the principles and demonstrate experience in supervision or construction with the relevant geosynthetics
  • a minimum of 10 days continuous one-to-one close proximity training as an assistant to an experienced CQA inspector with the relevant geosynthetic experience on a landfill contract, followed by mentoring and close supervision by the CQA engineer when those materials are being deployed

Landfills for inert waste

Where the proposed landfill engineering and infrastructure works are to be carried out at an inert waste landfill, read guidance on landfills for inert waste.

Landfill infrastructure

Where construction includes extraction or monitoring infrastructure, a CQA inspector must meet all of the following, unless agreed in writing with the Environment Agency:

  • a minimum formal qualification in science or engineering, for example OND, ONC or higher in civil engineering, mining engineering, engineering geology, building, quantity surveying or science or an equivalent relevant qualification
  • be able to understand the principles and demonstrate experience in supervision or construction of the specific extraction or monitoring infrastructure or drilling technique to be used
  • a minimum of 5 days, continuous one-to-one close proximity training as an assistant to an experienced CQA inspector on a landfill contract with the relevant drilling technique and construction of the specific extraction or monitoring infrastructure, followed by mentoring and close supervision by the CQA engineer during the drilling and construction works

Validation report

After you have constructed your landfill engineering, you must submit a CQA validation report to the Environment Agency before you dispose of waste in a new cell or development area.

Where you construct landfill infrastructure you must submit a validation report to the Environment Agency. You must submit it within 4 weeks of completing the construction and testing of the relevant infrastructure, or other time period agreed in writing with the Environment Agency.

The validation report provides the final ‘as-built’ construction and engineering details of the works.

Your validation report must include:

  • details of how you have complied with your CQA plan
  • justifications for any changes or deviations from the agreed plan
  • the manufacturers quality control testing and European Conformity (CE) certification for each geosynthetic product used
  • all design calculations or, if these have been included in the CQA plan, reference to the relevant sections of the CQA plan
  • as-built plans and cross-sections of the works showing the as-constructed location and level of each element of the landfill engineering or infrastructure
  • copies of the site engineer’s daily records
  • records of any problems or non-compliance and the solution
  • any other relevant site-specific information to prove the integrity of the construction
  • all test results

Test results include:

  • records of all tests showing compliance with the specification
  • records of any failed tests with a written explanation
  • details of the remedial action you took
  • references to the appropriate secondary post remediation testing
  • plans showing the location of all tests

You must provide a validation report for any work carried out as emergency measures.

The validation report must be signed by someone with at least route A or route B qualifications and experience for a CQA engineer.

You cannot dispose of any waste in a new cell or development area until you have submitted a CQA validation report for your landfill engineering and the Environment Agency has confirmed it is satisfied with it.

Carry out surveys

You must:

  • carry out topographical surveys to demonstrate you have constructed your landfill engineering and infrastructure in accordance with the agreed design
  • use your survey to provide as-built drawings as a record of the layout, locations, levels, shapes and gradients of relevant features

The target thickness of a mineral liner must equal the design thickness plus twice the limit of precision and tolerance of the survey method you use. You must confirm the tolerance of the survey method you use.

For mineral capping your method of thickness measurement must also take account of any settlement within the underlying materials.

The Environment Agency will accept topographical setting out and survey work carried out by your ‘in-house’ staff, your main contractor or a subcontractor.

You must:

  • use enough survey points to give confidence that you have met the thickness and level requirements
  • increase the frequency of survey points where there are curved surfaces, changes of gradient or direction and where mineral liners are designed to be less than 1 metre thick

Carry out check surveys

You must carry out check surveys to verify the accuracy of the main survey.

You must include a minimum of 10% of the main survey points on the sub-grade surface and the upper surface of the geological barrier as part of the check survey. These must be over at least 2 visits. They must include locations and levels of the leachate collection sumps, monitoring points and target pads.

Check surveys must be independent of the main contractor. They can be carried out by:

  • trained and competent staff – as long as they are not also responsible for the main survey
  • the CQA engineer
  • an independent surveying contractor

The person carrying out the check survey must confirm in writing the accuracy of the main survey and provide details of their suitability to do the work. You must include this in the validation report.

Keep records

You must keep your CQA plan and validation report until you apply to surrender your permit.