1、BSI Standards PublicationBS 8485:2015Incorporating corrigendum No.1Code of practice for thedesign of protectivemeasures for methane andcarbon dioxide ground gasesfor new buildingsPublishing and copyright informationThe BSI copyright notice displayed in this document indicates when the documentwas la
2、st issued. The British Standards Institution 2016Published by BSI Standards Limited 2016ISBN 978 0 580 92984 7ICS 91.120.99; 91.200The following BSI references relate to the work on this document:Committee reference EH/4Draft for comment 15/30283599 DCPublication historyFirst published October 2007S
3、econd (present) edition, June 2015Amendments/corrigenda issued since publicationDate Text affectedFebruary 2016 C1 Correction to Figure 5BS 8485:2015 BRITISH STANDARDContentsForeword ivIntroduction 11 Scope 22 Normative references 23 Terms and definitions 34 Overview of ground gas protection 55 Site
4、 investigation for ground gases 75.1 General 75.2 Preliminary investigation 75.3 Field investigation and monitoring 105.4 Conceptual site model for design of gas protection system 106 Process for ground gas characterization and hazard assessment 126.1 Risk assessment for ground gases 126.2 Methodolo
5、gies for ground gas characterization 126.3 Characterization using conceptual site model and gas monitoring data 136.4 Quantitative assessment of gas risk to characterize a site 187 Solutions choice and detailed design 197.1 Approach 197.2 Selection of appropriate protection measures 237.3 In-ground
6、pathway intervention 277.4 Detailed design 278 Implementation, verification and reporting 288.1 General 288.2 Site conditions and characterization of the ground gas regime 298.3 Design phase 308.4 Installation and verification phase 32AnnexesAnnex A (informative) Floor slab and substructure design 3
7、3Annex B (normative) Applicability and design of ventilation protectionmeasures 40Annex C (informative) Gas resistant membrane selection 58Annex D (informative) Characterization without gas monitoring data 61Annex E (informative) Sampling, examination and TOC testing of made groundfor the assessment
8、 of the potential for gas generation 63Annex F (informative) Worked examples 66Annex G (informative) Radon 78Annex H (informative) Volatile organic compounds (VOCs) 80Bibliography 83List of figuresFigure1BS8485 document flow chart 3Figure 2 Key ground gas ingress routes and accumulation areas within
9、unprotected conventional residential buildings 6Figure 3 Ground gas site characterization and assessment flow chart 8Figure 4 Example design conceptual site model cross sections 11Figure 5 Solutions choice flow chart 20Figure 6 Implementation stage 28Figure A.1 Example of potential influence of vibr
10、o stone columns for gasmigration 34Figure B.1 Typical passive ventilation arrangement with floor slab aboveground level 41BRITISH STANDARD BS 8485:2015 The British Standards Institution 2016 iFigure B.2 Typical passive ventilation arrangement with floor slab belowground level and low level vents 42F
11、igure B.3 Typical passive ventilation arrangement with floor slab belowground level and high level vents 42Figure B.4 Positive pressurization air blanket system 44Figure B.5 Typical active suction system with floor slab below ground level 45Figure B.6 Performance criteria for methane 48Figure B.7 Pe
12、rformance criteria for carbon dioxide 49Figure B.8 CFD computed volume flow through rates vs wind speed for variousmedia for a 30 m wide foundation 12 50Figure B.9 CFD computed volume flow through rates vs wind speed for variousmedia fora5mby5mwide foundation 12 51Figure B.10 Polystyrene void former
13、s 53Figure B.11 Geocomposite void former 55Figure B.12 Idealized plan of granular gas dispersal layer with network of gasdrains 57Figure E.1 Approach for detailed examination of made ground for theassessment of the potential for gas generation 66List of tablesTable 1 Check list for assessing the ade
14、quacy of a site investigation 9Table2CSbysite characteristic GSV 19Table 3 Building types 21Table 4 Gas protection score by CS and type of building 22Table 5 Gas protection scores for the structural barrier 23Table 6 Gas protection scores for ventilation protection measures 25Table 7 Gas protection
15、score for the gas resistant membrane 27Table 8 Information to be included in the design, installation and verificationreport 29Table A.1 Grades of waterproofing protection 36Table A.2 Risk rating summary 39Table B.1 Gas regimes considered in the DETR/PiT Guide for Design 12 46Table B.2 Gas regimes c
16、onsidered in the PiT Guide for Design 12 46Table B.3 Variables in the DETR/PiT Guide for Design 12 47Table B.4 Relative dispersal effectiveness of different gas dispersal layermedia 52Table D.1 Limiting values of thickness and organic content of made ground(after RB17 1, Table 1) 62Table F.1 Site A
17、ground conditions 67Table F.2 Site A gas monitoring data 68Table F.3 Maximum implied CS derived by combining the maximum observedflow rate and maximum observed concentrations from different boreholesduring any monitoring event 69Table F.4 Site A subsequent additional gas monitoring measurements 70Ta
18、ble F.5 Implied maximum CS derived from consideration of the maximumhazardous gas flow rate calculated from any single borehole standpipe duringany of these subsequent monitoring events 72Table F.6 Worst case implied CS derived by combining the maximum observedflow rate and maximum observed concentr
19、ations from different boreholesduring any of these subsequent monitoring events 72Table F.7 Minimum gas protection score (points) for different types of buildingat Site A 73Table F.8 Combinations of measures to provide a gas protection solution fordifferent types of building at Site A 73BRITISH STAN
20、DARDBS 8485:2015ii The British Standards Institution 2016Table F.9 Site B ground conditions 75Table F.10 Maximum implied CS derived from consideration of the maximumhazardous gas flow rate calculated from any single borehole standpipe duringany monitoring event 76Table F.11 Worst case implied CS der
21、ived by combining the maximum observedflow rate and maximum observed concentrations from different boreholestandpipes during any monitoring event 76Table F.12 Minimum gas protection score (points) for different types ofbuilding at Site B 76Table F.13 Combinations of measures to provide a gas protect
22、ion solution fordifferent types of building at Site B 77Summary of pagesThis document comprises a front cover, an inside front cover, pages i to v,pages 1 to 86, an inside back cover and a back cover.BRITISH STANDARD BS 8485:2015 The British Standards Institution 2016 iiiForewordPublishing informati
23、onThis British Standard is published by BSI Standards Limited, under licence fromThe British Standards Institution, and came into effect on 30 June 2015. It wasprepared by Technical Committee EH/4, Soil quality. A list of organizationsrepresented on this committee can be obtained on request to its s
24、ecretary.SupersessionThis British Standard supersedes BS 8485:2007, which is withdrawn.Information about this documentThis is a full revision of the standard, and introduces the following principalchanges: inclusion of more detailed recommendations on the interpretation of gasmonitoring data and ass
25、ignment of the gas screening value; inclusion of four building type definitions and amendments to the gasprotection scores recommended for different characteristic situations; inclusion of recommendations for reporting of gas protection measures atthe design, installation and post-construction (veri
26、fication) stages; revision of recommendations on the design of ventilation protectivemeasures; inclusion of recommendations on membrane selection and verification; inclusion of a method of site characterization without gas monitoring data(based on RB17 1); inclusion of worked examples of solution ch
27、oices for a range of differentground gas conditions and building types; inclusion of informative guidance on radon gas and volatile organiccompounds in Annex G and Annex H, respectively; inclusion of cross references to BS 8576:2013 and BS 10175:2011+A1:2013 asthe key sources of good practice on inv
28、estigations for ground gas; and inclusion of cross references to other relevant UK good practice guidancepublished since the publication of BS 8485:2007, including guidance fromCIRIA, NHBC, CL:AIRE and Wilson, Card and Haines.Use of this documentAs a code of practice, this British Standard takes the
29、 form of guidance andrecommendations. It should not be quoted as if it were a specification andparticular care should be taken to ensure that claims of compliance are notmisleading.Any user claiming compliance with this British Standard is expected to be able tojustify any course of action that devi
30、ates from its recommendations.It has been assumed in the preparation of this British Standard that theexecution of its provisions will be entrusted to appropriately qualified andexperienced people, for whose use it has been produced.Presentational conventionsThe provisions of this standard are prese
31、nted in roman (i.e. upright) type. Itsrecommendations are expressed in sentences in which the principal auxiliaryverb is “should”.BRITISH STANDARDBS 8485:2015iv The British Standards Institution 2016Commentary, explanation and general informative material is presented insmaller italic type, and does
32、 not constitute a normative element.The word “should” is used to express recommendations of this standard. Theword “may” is used in the text to express permissibility, e.g. as an alternative tothe primary recommendation of the Clause. The word “can” is used to expresspossibility, e.g. a consequence
33、of an action or an event.Notes and commentaries are provided throughout the text of this standard.Notes give references and additional information that are important but do notform part of the recommendations. Commentaries give background information.Contractual and legal considerationsThis publicat
34、ion does not purport to include all the necessary provisions of acontract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legalobligations.BRITISH STANDARD BS 8485:2015 The British Standards Institution 2016 vBRITISH STANDARDBS 8485:2
35、015This page deliberately left blankvi The British Standards Institution 2016IntroductionToxic, asphyxiating and flammable and potentially explosive ground gases canenter buildings and other structures on and below the ground. They variouslypose potential risks to occupants and users, and to the str
36、uctures themselves.This British Standard is intended to be used by designers of gas protectionmeasures and by regulators involved in the assessment of design solutions. Itrecognizes that there are a number of factors requiring consideration whichaffect the sensitivity of a development to the effects
37、 of ground gas, and thatthere is a range of design solutions available for different situations. It isanticipated that specialist advice is needed in the assessment of the ground gasdata and in the risk assessment phase.This British Standard provides a framework, in line with Model procedures forthe
38、 management of land contamination, CLR11 2, which provides designerswith information about what is needed for an adequate ground gas siteinvestigation. It also provides an approach to determine appropriate ground gasparameters that can be used to identify a range of possible design solutions forprot
39、ection against the presence of methane and carbon dioxide on adevelopment site. The framework is not prescriptive and professional judgementmay be made as to the acceptability of risk and whether there might be benefitin undertaking more rigorous site assessment or adopting conservative measuresin d
40、esign. Emphasis is placed on the justification and recording of riskassessments and design decisions throughout the process.A variety of gases might be present in the ground naturally, or be present as aresult of contamination of the ground, or arise from buried wastes. In additionto the main compon
41、ents found in air (nitrogen and oxygen), ground gas cancontain other gases (e.g. methane, carbon dioxide, carbon monoxide, hydrogensulfide, ammonia, helium, neon, argon, xenon, radon, etc.). It can also containvolatile organic compounds (VOCs) or inorganic vapours (mercury).Methane (which is flammab
42、le and an asphyxiant) and carbon dioxide (which istoxic and an asphyxiant) can originate from a range of sources including: land-filled wastes; degradable material present within the soil matrix of made ground; peat and organic matter within alluvial deposits; migrating landfill leachate; spilled or
43、 leaked petroleum hydrocarbons; silt formed in water bodies (e.g. ponds, docks and rivers); some natural deposits (e.g. chalk and coal measure strata); and leaks of mains gas (natural gas) and sewer gas.Wherever biodegradable materials are present, microbial activity producesmethane and/or carbon di
44、oxide depending on whether conditions are aerobic oranaerobic. A number of additional trace gases can also be produced.Permanent gases such as methane, carbon dioxide and carbon monoxide whichmight be present in coal measure strata can also emanate from old mineworkings (guidance is given in CIRIA R
45、eport 130 3). Combusting coal measurestrata, including waste in colliery spoil tips, can release carbon monoxide, as cansmouldering domestic waste. Under some circumstances, sulfur rich deposits suchas gypsum waste and some slags can release substantial quantities of hydrogensulfide; for example, wh
46、en sulfur-bearing wastes and domestic refuse are mixed.BRITISH STANDARD BS 8485:2015 The British Standards Institution 2016 11 ScopeThis British Standard gives recommendations on ground gas site characterizationand the choice of solutions for the design of integral gas protective measuresfor new bui
47、ldings to prevent entry of carbon dioxide and methane, and providea safe internal environment.This British Standard gives a process that can be used to demonstrate that risksposed by the potential or actual presence of carbon dioxide and methane havebeen addressed.This British Standard does not cove
48、r protection of new buildings against otherhazardous ground gases. Nor does this British Standard cover protection ofbuildings into which methane and carbon dioxide might be introduced by theactivities for which they are used (for example, water pumping stations).The retrospective design of protecti
49、on measures for completed buildings and thedesign of retrospective protection measures after completion of buildingconstruction are not covered in this British Standard.NOTE 1 Guidance on radon and VOCs is given in Annex G and Annex H.NOTE 2 This British Standard does not give recommendations on oxygen depletion.NOTE 3 The assessment and decision making stages are presented in the form ofprocess flow charts (Figure 3, Figure 5 and Figure 6
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