gas protection verification course · • verification plan should be part of detailed design and...

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Mick Corban – MEC Environmental Ltd

Gas Protection Verification Course

© MEC Environmental Ltd


Content:

• Guidance Documents • Regulators/Warranty Providers • Validation Strategy and Plans • Integrity Testing • Report Writing


Guidance Documents • CIRIA C735 “Good practise on the testing and verification of protection

systems for buildings against hazardous gases”

• BS8485 (2015) “Code of practice for the design of protective measures for methane and carbon dioxide ground gases for new buildings”

• CIEH (2008) The Local Authority Guide to Ground Gas


CIRIA C735 Gives practical guidance on Verification:

• Adopting a Risk Based Approach to Verification

• Verification Plan & Reporting

• Frequency & Type of Inspections/Testing

• Competency of Installers and Verifiers


CIRIA C735

INSTALLER COMPETENCE CIRIA C735 Section 3.3 states “It is essential that an appropriately qualified workforce is employed to install ground gas protection systems…an example of a relevant qualification for a supervisor installing gas protection measures is the Cskills level 2 NVQ Diploma – Installation of gas membranes…Operatives installing gas protection measures without this qualification should have attended the Cskills Gas Membrane Installation Up-skilling Course”


BS8485 (2015) States that: • Gas Protection measures must be buildable in so far that they can be built to

appropriate standards and verified

• Verification Plan should be part of detailed design and submitted and agreed with regulators prior to any work commencing on site.

• Verification Plan to detail, HOW, WHEN and by WHOM verification tasks will be carried out


CIEH (2008) Advises that:

• Planning conditions should include the requirement for verification of gas

protection measures

• Validating Installations of gas protection systems is arguably the most important part of the design and construction process

& Includes: • WATCHPOINTS for inspecting gas protection measures and Inspection Sheet

Proforma.


Guidance Documents CIEH (2008)


Regulators • The primary regulators for land affected by hazardous gases are the local

authorities (LA)

• Proposed Gas Protection System submitted to LA as part of remediation strategy

• The local authority planning department should include planning conditions based upon the gas risk for the site.

• A verification report demonstrating that the agreed protection measures have been installed is produced and submitted to planning department to gain discharge of the imposed condition relating to the gas protection system


Warranty Providers May also request verification prior to issuing warranties etc.


Verification Plan

• CIRIA C735 recommends a risk based approach

• Should be carried out at DESIGN stage

• Needs to be well defined to enable all parties to appreciate the scope and

how they could be affected


Verification Plan

Gas Regime: The verification plan should briefly DESCRIBE: • The ground gas regime (as identified in design report)

• The level of associated risk (CS2/Amber 1 etc)

• Type of floor construction and building type

• Brief description of gas protection elements (venting, membrane etc)


Verification Plan

Inspection Regime: The verification plan should SET OUT: • The scope and type of inspection (visual/testing)

• Who will carry out the inspections

• Independence and Competence of verification consultant (NVQ 2,

experience, qualifications etc.)

• Frequency of inspections and what will be inspected

• How the inspections will be recorded and presented


Verification Plan

Integrity Testing Programme: The verification plan should set out: • What test methods will be employed and why

• Who will carry out the testing

• What will be tested and the frequency

• How the inspections will be recorded and presented


Verification Plan

Installation Criteria/Performance: The verification plan should set out:

• What will be construed as damage/defect

• How will damage/defects be repaired and recorded


Risk Based Approach to Verification and Independence

• An informed and risk based approach should be taken to determine the level of verification and independence



• RISKS TO BE CONSIDERED

GAS REGIME Low Risk CS2/Amber 1 Intermediate Risk CS3/Amber 2 High Risk CS4 and above




DESIGN COMPLEXITY

Simple Few service entries. Gas membrane and sub floor void i.e. Beam and Block housing




DESIGN COMPLEXITY

Complex Variety of gas protection measures, columns, lift pits etc




NUMBER OF PLOTS/POURS/BUILDINGS Small <5 Medium 3-15 Large >10




INSTALLATION WORKFORCE NON – NVQ Qualified High Risk SKILLED NVQ Qualified Medium/Low



Example Installer CQA Sign Off Sheet


Integrity Testing

Testing of Seams

Probe Test Air Lance Test Pressure Test


Integrity Testing

Probe Test

Probe Test/Mechanical Point Stress Test Method: • Blunt object pulled along seams

• Unsealed areas will snag on the tool

• Covered in ASTM D4437


Integrity Testing

Air Lance Method: • Compressed Air Blown at Seam @ 345kPa

(3.5 bar / 50psi)

• Air Compressor needs to be capable of 9cfm free air delivery

• Lance positioned within 50mm of seam

• Some Companies carrying out air lancing with under powered equipment

• Check regulator gauge is correctly set

• Covered in ASTM D4437

Air Lance Test


Integrity Testing

Pressure Test Method: • Air channel Pumped with Air

• Dual Track Seam Required

• Difficult to do on thin membranes

• Covered in ASTM D5820 & D4437

Pressure Test


Integrity Testing

Testing of Surface of Membrane for Leaks/Holes

Tracer Gas/Smoke Test Dielectric Test


Integrity Testing

Tracer Gas/Smoke Method: • Underside of membrane pressurised and

gas injected

• Full area then swept to detect leaks

• No published standard but method and specification in Annex 2 of CIRIA C735

Tracer Gas/Smoke Test


Integrity Testing

Dielectric Method: • Electric Current introduced to Substrate

• Full area then swept to detect leaks with

electrically charge probe

• Standard and specification in Annex 2 of CIRIA C735

Dielectric Test

Example 0.4mm (400 microns) 250 x 20 = 5000 volts (5KV) 80% of 5KV = max test voltage 4KV


Reporting

Verification Report should contain: • Details of client/consultant/installer • Site details: Address, location etc. • Objectives and scope of work • Survey and Testing Proformas • Lines of evidence “photos etc” • A definitive statement that the plots/pours have passed failed • A statement detailing verification consultant “gas specific” experience and/or

qualifications

CIRIA C 735 states: Reporting should be clear and concise using logical text that will inform all stakeholders of the verification activities and results, it is neither practical or desirable for each house to have separate verification report…where possible a single report for the whole development should be issued


Any Questions