CIRIA Report

Finnamore, J., Barr, D., Weeks, J. Nathanail, C.P. (2002) Biological methods of assessment and remediation of contaminated land. CIRIA Report C575, CIRIA London. 

QUINION, D. W. Superplasticizers in concrete - a review of international experience of long-term reliability. CIRIA Report No. 62, CIRIA, London... 

Material from the Proceedings of the Institution ofCivil Engineers is includ by permission of the Council of the Institution. Material from the Structu Engineer is included by permission of the Council of the Institution of Structu Engineers. Table 1.1 is reproduced from CIRIA Report 63, Rationaiisation Safety and Serviceability factors in structural codes, by permission of i Director of the Construction Industry Research and Information Association. 

A numerical example of the use of these factors is presented in Section 4.5. A detailed discussion of the way in which these factors are used in the various codes of practice around the world is not within the scope of this text. Such a discussion is presented in the CIRIA Report No. 63 [61], and in particular in Table 6 of that report. In many of the codes the various factors have been assessed and combined into single figures. Forexample,in C.P. 110 The Structural Use of Concrete Part 1 1972, the factors 7 relating to the loads are called for which a single figuref is given for the various loads in the various limit states... 

The ultimate limit state design bending moment is 378 kN m but it is important to recognise which of the factors y, and yc, that the partial factor values used, represent. According to CIRIA Report 63, the values recommended in C.P. 110 include an allowance for all these factors except which is intended to take account of the nature of the structure and its behaviour. In this problem y will also be taken as unity and so the design bending moment for the ultimate limit state remains at 378 kN m. 

Rationalisation of Safety and Serviceability Factors in Structural Codes, CIRIA Report 63, July 1977. 

CIRIA (1996). Sea Outfalls - Inspection and Diver Safety. CIRIA Report 158. 

Paterson, W.S. and Ravenhill, K. Reinforcement connector and anchorage methods, CIRIA Report 92, CIRIA, London, 1981. 

McDowell, P.W., Barker, R.D., Butcher, A.P., Culshaw, M.G., Jackson, P.D., McCann, D.M., Skipp, B.O., Matthews, S.L. and Arthur, J.C.R. 2002. Geophysics in Engineering Investigations. Construction Industry Research and Information Association (CIRIA), Report C592, Engineering Geology Special Publication No. 19, Geological Society, London. 

Cadei, J. M. C., Stratford, T. J., Hollaway, L. C. and Duckett, W. G. (2004), Strengthening metallic structures using externally-bonded fibre-reinforced polymers , CIRIA Report RP 645, CIRIA, London. 

CUR/CIRIA, Manual on Use of Rock in Coastal Engineering, CUR/CIRIA Report 154 Gouda, the Netherlands (1991). 

CEM, Coastal Engineering Manual, US Army Corps of Engineers, Vicksbmg (2006). CIRIA-CUR-CETMEF, The Rock Manual, CIRIA, London (2007) (also CUR/ CIRIA, Manual on use of rock in coastal engineering, CUR/CIRIA report 154, Gouda, the Netherlands, 1991). 

Irvine, D. J. and R. J. H. Smith. 1992. Trenching Practice CIRIA Report 97, rev. ed. London CIRIA. Trenching is an area of construction that, if incorrectly carried out, can result in deaths and disasters this provides guidance on good practice. 

Table 3.2 Useful properties of some hazardous ground gases (see also CIRIA Reports 130 and C659I665)... 

Table 3.3 Properties of some commonly occurring vapours (see also CIRIA Report C6S9I66S)... 

This is the equation used in the Johnson and Ettinger (1991) model for vapour diffusion in the ground. Values of the diffusion coefficient of methane for various soils and rocks have been given in CIRIA Report 152 (O Riordan and Milloy, 1995). 

CIRIA, Report C659/665 Assessing risks posed by hazardous ground gases for buildings (Wilson et al, 2006/2007)... 

CIRIA, Report 131, The measurement of mefhane and other gases from the ground (Crowhurst and Manchester, 1993)... 

CIRIA, Report 151, Interpreting measurements of gas in the ground (Harries et ah, 1995)... 

The following guidance is based on the information provided in Wilson and Haines (2005) that was subsequently incorporated into CIRIA Report C659/665 (Wilson et ah, 2006/2007). It focuses on ground gas rather than vapours. For vapours the number of wells required to characterise a source will be driven by the extent of the chemical contamination of the groimd or soil. 

Based on the guidance in CIRIA Report 150 a decision framework such as the one in Table 5.1 can be developed. However, three wells and four sets of readings should be considered an absolute minimum for even the smallest site. 

The following discussions are intended to assist the reader in following the risk assessment process that is discussed in CIRIA Report C659/665 (Wilson et al, 2007) and to follow the flow charts that are included in that document. 

Further guidance on conceptual models is provided by the Environment Agency (2001) and in CIRIA Report C659/665. The Environment Agency report gives the following excellent advice... 

Guidance on the assessment of gas data is provided in CIRIA Report C659/665. The following paragraphs provide some useful advice on specific frends and patterns to look out for in gas monitoring data. 

CIRIA Report C659/665 has two methods of characterising the level of risk associated with a site, one that has heen specifically developed for the NHBC that applies for low rise housing and the other for any other type of development. Both methods use the gas screening value (GSV) to characterise a site. The GSV is given by ... 

The most commonly used method of quantitatively assessing risk on gassing sites is that described in CIRIA Report 152. This uses a fault tree analysis to provide a numerical estimate of the risk (i.e. a probability that an adverse effect will occur in any year or other specified period). The method described below varies from the method described in CIRIA 152, based on published papers (Hartless, 2004 Sladen and Dorrell, 2001) and the present authors experience. 

Useful methods of defining probabilities for some of the events have been given by Hartless (2004). These are summarised below and correct some of the errors that have been noted in the method described in CIRIA Report 152 (CIRIA, 1995). 

The method described in CIRIA Report 152 assmned that the actual entry rate of methane into the cupboard was the diffusion rate of methane from the adjacent landfill. However, this possibly does not adequately represent the rate at which methane will enter a cupboard. A more realistic indicator of methane surface emissions into the cupboard can be gained using borehole flow rates or calculated surface emission rafes. One mefhod of doing fhis, if there is a sufficient data set, is by xmdertaking statistical analysis of the gas monitoring results (see Box 6.5). 

In CIRIA Report 152 the construction considered was an in situ concrete floor slab incorporating a HDPE membrane. The report went on to postulate that on the basis of plan areas there was a probability of 0.001 that there would be a crack in the floor slab beneath a cupboard. This was just a hypothesis. Any assessment of the risk of membrane failure will be based on judgment as there are some factors that are difficult to apply numbers to (e.g. the risk of a worker drilling through a membrane). However, the scoring method described in Box 6.6 can help as an aid to judgment. 

This topic is not covered in CIRIA Report 152. There are different methods of venting xmderfloor voids and three common scenarios are ... 

Carbon dioxide concentration and oxygen depletion N/a N/a The critical level of methane is 1 % v/v. The critical level for carbon dioxide is 1.5% v/v and for oxygen depletion any gas must remove oxygen so that levels fall to 17% v/v or below before effects take place (CIRIA Report 149). This requires more than 1 % v/v of gas. So worse case is 1 % v/v design criteria. 

Density of ground gas 0.717 kg/m N/a From CIRIA Report 152 value for methane... 

A wide range of methods can be used to form in ground barriers. Some typical examples are shown in Figure 7.2. Comprehensive guidance on barrier design and construction has been given in CIRIA Report C149 (Card, 1995), CIRIA Special Publication 124 (Privett et al, 1996) and CIRIA Report C 557 (Barry et al, 2001). The reader is referred to these documents for more detailed information. 

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