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INfrastructure Why more guidance is needed Verification of gas 2. Define the need for and scope of In the past 20 years, several good practice protection systems verification activities during construction guidance documents have been developed Verification is an important step for the (ie what needs to be inspected and on hazardous ground gases: management of gas hazards and mitigation when, and the information that should BS 8485:2007Code of practice for the of vapour risks for remediation projects. be recorded during inspections). characterization and remediation from Although many local authorities now 3. Describe the principles, pros and cons ground gas in affected developments require it, the standard of verification of the various integrity test methods in through inspections and testing varies different circumstances. Privett et al (1996) Barriers, liners and cover systems for containment and control 4. Devise guidance to aid decision makingconsiderably. There is limited guidance on of land contamination, SP124 for the selection of appropriate integritygood practice and regulatory expectations Wilson et al (2007) Assessing risks posed gas resistant membranes. test methods.especially with respect to integrity testing of by hazardous ground gases to buildings 5. Identify practical issues that may (revised), C665 Verification activities have been described affect the verification process and Baker et al (2009) The VOCs Handbook. to some extent in several other guidance provide guidance on the management Investigating, assessing and managing risks documents including by the Environment of such issues. from inhalation of VOCs at land affected by Agency: 6. Set out the inspection and reporting contamination, C682 Model procedures for the management of details that are important for the CL:AIRE (2009)A framework for land contamination, CLR11 (2004) preparation of the verification report assessing the sustainability of soil and (to align with the requirements of the groundwater remediation reporting checklists, GPLC1 (2010a) Agency guidance, 2010b).model procedures and EnvironmentGuiding principles for land contamination Welburn et al (due 2012) Remediating Verification of remediation of land and mitigating risks from volatile organic contamination, SC030114/R1 (2010b) Adherence to the guidance and advice in compound vapours from land affected by the final report will:There is not a great deal of pertinent, contamination, C716 relevant and up-to-date guidance and provide clients, regulatory authorities, With increasing economic constraints, advice with respect to verification or (including contaminated land officers many land remediation projects now have integrity testing of gas/vapour barriers. and approved inspectors) and other a much smaller budget. Also with the However, there is recent and relevant UK stakeholders (homeowners, asset inevitable tightening of Building Regulations, guidance with respect to verification of managers) the confidence that the construction professionals need to find other remediation works, most notably hazardous gas mitigation measures have ways to ensure that their remediation in the Environment Agency’s model been designed and constructed to the approach remains efficient but still meets procedures (2004). appropriate standard rigorous specifications. reduce the long-term liability of Selection of the appropriate developers in hazardous ground gasNew CIRIA projects gas protection systems to complete a suite of work on hazardous measures have been part of theprojects where hazardous gas protectionCIRIA has now begun two new projects It is 20 years since BRE first published ground gases: development guidance on the use of gas resistant membranes below floor slabs to prevent improve the confidence of the the ingress of ground gas (Hartless 1991). construction industry (through theGood practice on verification and Since then membrane has been installed provision of clearer guidance) withtesting of ground gas protection on many sites and it could be argued that respect to the need for scope and costs(RP960)systems for buildings experience would have been accumulated. of verification and testing activities This project will help contaminated land associated with the installation of gas Also, many publications, eg Wilson et al protection measures in buildings.professionals, particularly developers/ contractors and technical advisers such (2007), have given some guidance on what membrane should be used to deal with Gas membrane and other plasticas consultants and structural engineers. hazardous ground gases, although these are barriers in land affected byThe project objectives have been defined often restricted to bulk gases (methane and contamination (P2990)with respect to the three main elements of this work: carbon dioxide). the verification of the installation of gas/ This project intends to provide practical, So there needs to be more explanation to vapour barriers evidence-based guidance on aspects of help clients understand what they should testing the integrity of gas/vapour plastics in or close to the ground that can be looking for, ie not just thickness of the barriers be affected by contamination. This work will material in the selection process. recording and reporting of all verification explore what are the risks of hydrocarbons, activities and results. VOCs, phenols and other hydrocarbons The over or incorrect specification of and contaminants attacking membranes and membrane can lead to problems, eg an other plastic barriers. The project will helpAccordingly, the five objectives of the insufficient specification could cause ingress practitioners optimise costs when usingproject are to: or gases, which means significant costs to 1. Determine good practice for the design plastic membrane and other plastic barriers developers, contractors and consultants. and adoption of verification strategies in contaminated land. However, membrane manufacturers, even for gas protection systems in buildings with those that have already obtained to mitigate risks from hazardous ground To get involved in these projects contact BBA or CE marking for their products gases (methane, carbon dioxide, radon Joanne Kwan, CIRIA, on email: joanne. sometimes have difficulties in satisfying the and VOCs). kwan@ciria.org or tel: 020 7549 3300 needs of their clients. 22


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