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BOC Immingham Dissolved Acetylene Project Environmental Statement: Vol. 2 Main Text
Impact Assessment
Construction
7.73 The land contamination impact assessment is based on the change in risk between the baseline
and the construction phase. Construction activities by their very nature (and as described earlier)
slightly increase the likelihood of exposure to contamination introduce potential sources. Good
practice methods will be employed which will include measures to minimise the pathway and or
reduce the source potential for exposure. A CEMP will be prepared and implemented, which will
ensure that appropriate procedures will be in place to minimise risks and provide a means of
monitoring their effectiveness. In addition, a construction waste management plan (WMP) will be
developed and implemented as part of the CEMP. On the basis of the above, the construction
phase contamination risk assessment is summarised as follows:
� on site human receptors: the probability of the PPL is considered ‘low likelihood’ and the
consequence is considered ‘mild’. Construction activities could increase the potential for
exposure to contaminants in soil (if these are present) and vapour ground gas because
construction activities involve the handling of soil and have the potential to encounter
groundwater by excavation dewatering (potential sources). However, good practice methods
are implemented to reduce such exposure and the risk identified as ‘low’;
� offsite human receptors: the probability of the PPL is considered ‘unlikely’ and the
consequence is considered ‘mild’. Construction activities could increase the potential for
exposure to contaminants in windblown, soil-derived dust (if contaminants are present) and
migrating vapour ground gas because construction activities involve the handling of soil
(potential sources) and potentially changing the vapour ground gas regime. However, good
practice methods are implemented to reduce such exposure activities and the risk identified
as ‘very low’;
� controlled waters receptors (groundwater in the Superficial Deposits): the probability of the
PPL is considered ‘low likelihood’ and the consequence is considered ‘mild’. Construction
activities could increase the potential for mobilisation of contaminants, for example, increased
infiltration and leaching, accidental spillage of pollutants, etc. but good practice methods are
implemented to reduce this possibility and the risk identified as ‘low’;
� controlled waters receptors (Humber Estuary): the probability of the PPL is considered ‘low
likelihood’ and the consequence is considered ‘mild’. Construction activities could increase
the potential for mobilisation of contaminants, for example, in surface water runoff, but good
practice methods are implemented to reduce this possibility and the risk identified as ‘low’;
� on site property receptors (crops): this PPL no longer exists as the on site crops will have
been removed;
� offsite property receptor (crops): the probability of the PPL is considered ‘unlikely’ and the
consequence is considered ‘minor’. Construction activities could increase the potential for
mobilisation of contaminants in windblown, soil-derived dust, but good practice methods are
implemented to reduce this possibility and the risk identified as ‘very low’; and
� offsite property receptor (buildings): the probability of the PPL is considered ‘unlikely’ and the
consequence is considered ‘minor’. Construction activities could increase the potential for
mobilisation of vapours ground gas but good practice methods are implemented to reduce
this possibility and the risk identified as ‘very low’.
7.74 Based on the above, the impact assessment is summarised in Table 7.3.
5100935.404 Environmental Statement August 2011 107