Guidance on Ground gases, VOC s & Radon. Validation &Verification. By: Peter Atchison

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1 Guidance on Ground gases, VOC s & Radon. Validation &Verification. By: Peter Atchison

2 Permanent Gas and VOC definitions Permanent Gas Element or compound that is a gas at all ambient temperatures likely to be encountered on the surface of the earth except Radon! Volatile Organic Compound a) organic compound that is volatile under normal environmental/atmospheric conditions, although it can be found in the ground in the solid, liquid and dissolved phase form as well as in gaseous phase. (from CIRIA Report 682) b) organic compound which is liquid at 20 C and which generally has a boiling point below 180 C (after ISO CD 11074:2011)

3 The Ground Gas Hierarchy Bulk gases: Methane, Carbon Dioxide NHBC - Guidance on evaluation of development proposals on sites where methane and carbon Dioxide are present Report No RO1 (04) January 2007 CIRIA - C665 Assessing Risks posed by hazardous ground gases to buildings 2007 BS8485 Code of Practice for the characterisation and remediation from ground gas in affected developments Dec 2007 BS 8576 Guidance on investigations for ground gas Permanent gases and Volatile Organic Compounds (VOCs) VOC/s CIRIA C716 RADON BRE s and overdue updating Missed out of the Building regulations revision last year - Is Radon treated as a second rate risk?

4 BS 8576: 2013 Guidance on investigations for ground gas Permanent gases and Volatile Organic Compounds (VOCs) In final draft now Links together key recent documents into a full British Standard Monitoring and sampling of ground gases Does not cover Radon

Preliminary Investigation Desk study and site reconnaissance (site walkover) in line with BS 10175 and establishes the site investigations to follow

5 Preliminary Investigation Desk study and site reconnaissance (site walkover) in line with BS and establishes the site investigations to follow based on the objectives set For sites in which migration of permanent ground gases is to be investigated, a conceptual model cross section should be included.

6 CIRIA C716 Remediating VOC Risks Lead authors Arcadis Funders included: PAG & GGS Covers: Petroleum hydrocarbons Halogenated hydrocarbons N, S & O containing organic compounds CIRIA C

7 CIRIA C716 The guidance leads the reader through the three stages of remediation risk mitigation as outlined by DEFRA and the Environment Agency of England and Wales (2004) namely : 1 Development of the remediation strategy 2 Design and implementation of the remediation strategy 3 verification of the remediation strategy (including long term monitoring and maintenance)

8 Mechanism of Harm Ground gas seeps into enclosed spaces (e.g. Buildings), and collects. Basements are particularly susceptible to large accumulations (as greater area in contact with soil) High concentrations can build up, depending on local geology, atmospheric conditions & ventilation Methane explosive risk if concentrations between 5% and 16% (Acute risk!) Carbon Dioxide asphyxiates in excess concentrations; health affecting at lower concentrations (chronic acute) VOC s Mainly a odour nuisance but deleterious to health at high concentrations or long term exposure.(generally chronic risk) Radon - when inhaled, these irradiate the lungs and increase risk of developing lung cancer. Radon (Chronic Risk) and difficult to consider in isolation from other causes

9 Concentration of gases in the atmosphere (excluding water vapour) Gas Percentage by volume Nitrogen Oxygen Argon 0.93 Carbon dioxide Neon Helium Krypton Hydrogen Xenon Radon <

10 What is RADON? A naturally occurring element A radioactive gas Colourless & odourless Comes from radioactive decay of Radium Radium comes from radioactive decay of uranium

11 RADON Levels Average UK background radon concentration outside is 4 Bq m -3 Outside, radon gas dissipates harmlessly Average level inside UK homes is c20 Bq m - 3 For levels below 100 Bq m -3, individual risk remains relatively low However, risk increases as the radon level increases

12 Radon deaths compared to other causes of UK premature deaths per year

13 Radon Exposure Risks

14 Things to Remember! Type of Protection Membrane choice Detailing / Design Installation / Installation / Installation Validation Protection is only as good as its weakest part. Right First time saves cost!

15 Validation & Verification New document not yet published Approaching final draft stage Likely to be published in 6 months time!!!!! Aimed at clients and engineers / specifiers in order to assist them in setting appropriate levels of validation according to what system has been used and by whom installed. Uses all state of the art validation techniques from visual inspection to integrity testing

16 Validation and Verification Presumptions: ALL installations should be subject to some form of validation Validation should be proportionate to the risks from the site AND the experience of the installation operatives Validation should be conducted by suitably qualified INDEPENDENT practitioners. In the event of appropriate self validation this should be AUDITED by a suitably qualified independent auditor

17 Validation & Verification Table A (Low Rise Housing Only) Gas regime/ Risk Type of Slab Installer Experience Suggested Levels of Verification & Integrity Testing All Slabs General builder/groundworker/ landfill operative [No relevant qualification 1 ] Basic & Full Radon Protection Area, CS2* (with venting**) CS2* (no venting) or CS3* (with venting**) VOC & Hydrocarbons CS3* (no venting) or CS4* (with venting**) Qualified 1 and experienced installer (Minimum 1 operative to hold qualification) General builder/groundworker/ landfill operative [No relevant qualification 1 ] Qualified 1 and experienced installer (Minimum 1 operative to hold qualification) Qualified 1 and experienced installer (ALL operatives to hold qualification) Independent Consultant 4 to conduct a thorough visual inspection of the first plot, including vented void, subgrade, & membrane and after placement of floor reinforcement if no protection layer provided. On successful completion of the first plot independent validation inspections to be carried out at a frequency of around 1 in 10 plots. Contractor to supply plot sign off sheets including photographs to validation consultant for all other plots Consideration given to the need for and scope of integrity testing in the event of continuing concerns identified by visual inspections 3 Independent Consultant 4 to conduct a thorough visual inspection of the first plot, including vented void, subgrade, & membrane and after placement of floor reinforcement if no protection layer provided. On successful completion of the first plot independent validation inspections to be carried out at a frequency of around 1 in 20 plots. Contractor to supply plot sign off sheets including photographs to validation consultant for all other plots Consideration given to the need for and scope of integrity testing in the event of continuing concerns identified by visual inspections 3 Independent Consultant 4 to Inspect first 10 plots including vented void, subgrade, & membrane and after placement of floor reinforcement if no protection layer provided, furthermore all joints, pipe penetrations, corners etc. should be air lanced to ASTM D On successful completion of the first 10 plots independent validation inspections including air lancing to be carried out at a frequency of around 1 in 20 plots Contractor to supply plot sign off sheets including photographs to validation consultant for all other plots Consideration given to the need for and scope of integrity testing (e.g. initially on 30-50% of plots then falling to 0-10% of plots if first tranche gives acceptable results and no concerns raised by visual inspections). Independent Consultant 4 to Inspect first 5 plots including vented void, subgrade, & membrane and after placement of floor reinforcement if no protection layer provided, furthermore all joints, pipe penetrations, corners etc. should be air lanced to ASTM D On successful completion of the first 10 plots independent validation inspections including air lancing to be carried out at a frequency of around 1 in 20 plots. Contractor to supply plot sign off sheets including photographs to validation consultant for all other plots Consideration given to the need for and scope of integrity testing (e.g. initially on 10-25% of plots then falling to 0-5% of plots if first tranche gives acceptable results and no concerns raised by visual inspections) 3. Independent Consultant 4 to Inspect all plots, including vented void, subgrade, membrane and after placement of floor reinforcement if no protection layer provided, furthermore all joints, pipe penetrations, corners etc. should be air lanced to ASTM D % Leak Detection should also be considered. Consideration given to the need for and scope of integrity testing (e.g. initially on 30-50% of plots then falling to 0-10% of plots if first tranche gives acceptable results and no concerns raised by visual inspections) 3. Notes 1) Relevant qualification is NVG Level 2 Qualification in Gas Protection Installation [see report text] 2) Prior to Commencement of works the contractor should produce a detailed installation plan including: method statement, CQA procedures and qualifications, on receipt of these the validation protocol could be increased or reduced. 3) Consideration should be given to carrying out integrity testing/ leak detection (i.e. smoke, tracer gas or dielectric testing) on the above basis and/ or if an unacceptable amount of damage/ loss of integrity is found during visual inspections. In this instance the consultant should discuss with the relevant personnel, strategies to prevent this recurring. This could include changing material, improving subgrade preparation, putting up warning signs to reduce the amount of trafficking etc. 4) Independent Consultants should be appropriately trained and experienced. An example of relevant training could be a certificate of attendance for the C. Skills Installation of Gas Membrane Sector Apprenticeship and Up-Skilling Course (or equivalent), which includes inspection and integrity testing as part of its syllabus. Appropriately experienced could be say 3 years of building surveying, engineering or site supervision/ inspection experience. Less experienced staff should be accompanied by appropriately experienced staff at least for the initial visits. Inspections. A statement detailing the required qualifications and experience should be included in the Verification Plan. 5) Air Lancing is the only integrity test that has an independently recognized international standard that is suitable for testing taped and welded seams and should be used at the frequency suggested in the table. 6) This table should be used for guidance and is not intended to be used in lieu of sound professional judgment. * Gas regime defined by Characteristic Situation as set out in CIRIA C665 (and all other recent good practice guidance and British Standards) ** Assumes Venting designed to keep steady state concentration of CH4 below 1% in void, sites designed with higher levels of gas in the void should adjust the frequency of inspection and testing as deemed necessary.

18 Quality is never an accident; it is always the result of high intention, sincere effort, intelligent direction and skilful execution; it represents the wise choice of many alternatives. William A. Foster

19 The three most important elements of membrane efficiency INSTALLATION INSTALLATION INSTALLATION

20 How to do it well!

21 And How not to!

22 The good!

23 The bad!

24 And The Ugly!

25 Attention to detail

Ventilation & ancilliary products Void former

26 Ventilation & ancilliary products Void former Made from cuspated High Density Polyethylene (HDPE). High strength and crush resistance. Available as fully wrapped or single-sided geotextile. Cross linked butyl sealant Suitable for joining polyethylene membranes. Very low gas transmission.

27 Improving standards Construction Skills National Occupational Standards (NOS) Gap identified in the National Qualification Framework (NQF) Gas membrane installation for domestic and industrial/commercial buildings Existing standards for installing geomembranes NOSs should reflect current occupational practice Mandatory Core Standards

28 NVQ/SVQ Structure MANDATORY UNITS Unit No. VR 01 Conform to General Workplace Safety Unit No. VR 02 Conform to Efficient Work Practices Unit No. VR 03 Move and handle resources Unit No. GM 01 Prepare to install venting media and gas membranes Unit No. GM 02 Install venting media and gas membranes

29 Sealing Techniques

30 Validation / Verification Increasingly being specified as part of a well designed solution May consist of a variety of or combination of practices and should be specified appropriately according to risk There is no One off Validation! May consist of: Check for compliance with specification (Including materials, qualifications of installation operatives and position of components.) Visual inspection of work Close physical inspection of work including pick testing Seam and seal testing using test equipment Full installation integrity testing using gas, smoke or dielectric testing techniques. CIRIA Project currently under way to offer guidance due published 2013

31 Always confirm expectations pre-construction Combination of protection elements DPM or proprietary gas resistant membrane Detailing in line with current good practice Self installation or specialist sub contractor Third party validation or Detailed report with photographs Integrity testing Certificate of integrity

Is the contractor competent to self install for Amber 1?

32 NHBC guidance: Amber 1 & Amber 2 Checklist Is there sufficient provision for ventilation? Is there a clear path to atmosphere? Is the membrane appropriate? Is the contractor competent to self install for Amber 1? Have repairs been carried out (correctly)? Is visual inspection adequate? Has the contractor employed a specialist for Amber 2 Is a certificated Integrity Test required?

33 Gas membrane installation: Concrete prep on Full Line Out

34 Gas membrane installation: 3-D detailing

35 External corner with level change

36 Internal corner

37 Wind posts & penetrations

38 Changes in level

39 Validation Report types Often based on LCC pro forma Must contain confirmed details of Project particulars & materials used. Should contain photographic records Should be completed by a competent person May involve validation via integrity testing Typically in report format 4-10 pages typical. Should be plot and visit specific (You can only validate what you have seen!)

40 Examples of Report format

41 Report extract 1

42 Report extract 2

43 Validation & Verification Validation and verification is the single most important aspect of barrier installation and has been implied for many years. Only with the development of this document will designers, clients, practitioners and the like be able to substantiate the presumptions of the past 20 years. NOS s VR 612 and 613 describe the process NVQ level 2 qualification in gas membrane installation has been developed and offered by NSAC Up-skilling course for installation operatives available via the British Geomembrane Association

44 How it shouldn t be done: Pipe entry missed

45 How it shouldn t be done: End lap not sealed

46 How it shouldn t be done: Both together

47 How it shouldn t be done: Lack of detailing awareness

48 How it shouldn t be done: Run out of gas membrane?

49 Integrity testing Is a TOOL of validation Whilst IT may be considered the ultimate verification. It should be used appropriately. There are a number of different methods currently available. Each are appropriate for certain sites Further information will be included in CIRIA guidance on validation and verification Due 2013

50 Integrity testing

51 Set up

52 Introduce tracer gas

53 Scan and repair

54 In conclusion Much has been accomplished over the last 10 years Much is still to be done Quality design relies on quality data. Good quality materials need good quality workmanship to perform Standards exist and can be applied Validation and verification form part of a quality design So could you be a validator..?

55 Spot The difference!

56 Thank You And remember.. Be a yardstick of quality. Some people aren't used to an environment where excellence is expected. Steve Jobs ( )

57 Thank you Peter Atchison

Understanding Gas Protection Measure Selection within Waterproofing Systems. John Naylor Technical Director

Understanding Gas Protection Measure Selection within Waterproofing Systems John Naylor Technical Director The Main Hazardous Gases H 2 S CO CH 4 H 2 N 2 Rn CO 2 VOCs Sources of UK ground-gas Natural Bedrock