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BOC Immingham Dissolved Acetylene Project Environmental Statement: Vol. 2 Main Text
Assessment Criteria
Introduction
7.33 Atkins has developed definitions of probability and consequence based on guidance from CIRIA
C552 47 and National House Building Council EA R&D 66 48 which provide general guidance on the
development and application of the consequence and probability ‘matrix approach’ to
contamination risk assessment, CLR 11 35 , Defra Circular 01 2006 34 and EA guidance on pollution
of controlled waters.
7.34 Based on the above, Atkins’ definitions of probability are as follows:
� high likelihood: the PPL exists and it is very likely to result in harm pollution in the short term
and or will almost inevitably result in harm pollution in the long term and or there is current
evidence of harm pollution. Likelihood is defined as more likely than not and meets the
definition of ‘significant possibility’ under Part 2A of EPA 33 1990;
� likely: all the elements (source-receptor-pathway) are present and in the right place which
means it is probable that a PPL is present. Circumstances are such that harm pollution is not
inevitable, but possible in the short term and likely over the long term;
� low likelihood: all the elements (source-receptor-pathway) are present and in the right place
which means that it is possible that a PPL is present. However, it is by no means certain that
even over a longer period harm pollution would take place and harm pollution is less likely in
the short term; and
� unlikely: all the elements (source-receptor-pathway) are present and in the right place which
means that it is possible that a PPL is present but circumstances are such that it is
improbable that harm pollution would occur even in the very long term.
7.35 Classifications of consequence are as follows:
� severe: short term (acute) damage to human health likely to result in ‘significant harm’ (as
defined by Part 2A 33 ), exposure to hazardous substances is likely to result in reportable death
major injury. Short term risk of pollution of sensitive water resources (pollution of a principal
aquifer, groundwater source protection zone and drinking water supply, reducing quality) and
pollution meets the Part 2A 33 definition. Catastrophic damage to buildings foundations
services and harm meets the definition of ‘significant harm’ under Part 2A 33 . Substantial loss
in the value of crops or domestically grown produce, death of livestock, domesticated animals
or wild animals and harm meets the definition of ‘significant harm’ under Part 2A 33 ;
� medium: chronic damage to human health, likely to result in ‘significant harm’ (as defined by
Part 2A 33 , exposure to hazardous substances likely to result in reportable dangerous
occurrence, exceedence of workplace exposure limits. Pollution of sensitive water resources
(pollution of a principal aquifer but outside a groundwater protection zone and industrial
agricultural water supply, but insufficient to reduce the water quality). Substantial damage to
buildings and foundations rendering them unsafe and to services, impairing their function and
harm meets the definition of ‘significant harm’ under Part 2A 33 . Substantial diminution in yield
(over 20% reduction) of crops or domestically grown produce and serious disease physical
damage to livestock, domesticated animals or wild animals and harm meets definition of
‘significant harm’ under Part 2A 33 ;
5100935.404 Environmental Statement August 2011 96