Environmental Engineering Reference
In-Depth Information
statutory body responsible for nature conservation) was an important element in the
process, given the need to specifically address the potential impacts on the SPA. It was
important to ensure that the document presented to the local authorities and other
consenting authorities also fulfilled the requirements of this statutory consultee.
The Steering Group was involved in determining the scope of the CEA, but no public
participation was arranged for this stage of the study. The scoping exercise identified
those issues where there was potential for cumulative effects to occur. These included,
during the construction phase, effects on bird species on the SPA site and on traffic, and
during the operational phase, effects on estuary hydrodynamics, water quality and aquatic
ecology. Data was made available for the study by the developers, including information
from existing EIA work already undertaken; some additional modelling work was also
carried out. The information provided included the probable timing of activities within
the construction programmes for each project, the manpower requirements for these
activities and associated traffic movements. Existing baseline data available included the
range of bird species present at different times of year in the SPA, and their vulnerability
to disturbance (Piper 2000). Prediction of cumulative impacts was assisted by the
production of a series of tables and matrices, which brought together the levels and
timing of impacts identified for each project. These included
• a combined timetable of major construction works;
• bird disturbance potential (sensitivity in each month of the year);
• timetable of construction work potentially affecting birds, and monthly sensitivity;
• potential aquatic impacts of the developments; and
• predicted traffic pattems (vehicles per day, for each month of the construction works).
In arriving at predictions, it was decided to use the developers' best estimates, rather than
a worst-case scenario approach (Piper 2001a).
As a result of the cumulative impacts predicted, a number of additional mitigation
measures were proposed (in addition to those measures that would have been considered
had the schemes been assessed separately). Examples included the scheduling of certain
noise-generating construction activities such as piling outside sensitive periods (e.g. bird
roosting), and the introduction of staggered working hours to reduce peak traffic
volumes. It was also proposed that the design of adjacent projects should be integrated in
such a way as to minimize environmental impacts. An example was revisions to the
design of the ferry berth structure to complement the design of the outfall from the water
treatment works, and so enhance mixing of water in the estuary. Finally,
recommendations were made for continued monitoring of the cumulative effects on birds
and the aquatic environment. Responsibility for funding this work was shared amongst a
sub-group of the developers involved in the proposed schemes (Piper 2000).
9.7.3 Costs and benefits of the CEA process
Piper (2000) has assessed the costs and benefits associated with the Humber Estuary
CEA study, drawing on a series of interviews with those involved in the process,
including the developers, the relevant local authorities, other consenting authorities and
statutory consultees. The views of these different stakeholders are summarized below,
beginning with the developers of the proposed schemes.
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