Newlands Cross Upgrade EIS - European Investment Bank

South Dublin County Council N7 Newlands Cross Upgrade
Environmental Impact Statement
Arup Consulting Engineers
15.2.9.2 Operational Phase
• It is proposed to utilise the existing drainage outfalls post construction where practical.
The outfall peak flows will be increased post construction due to increased impermeable
road surfaces; therefore flow regulation is required to prevent over capacity of receiving
watercourses. This will be provided by means of oversizing drainage pipes and using a
flow regulating device (such as HydroBrake or equivalent) where the proposed drainage
outfalls.
• There will be no use of herbicides, pesticides or artificial fertilisers in any landscaping or
subsequent maintenance within 2m of a watercourse. Applications of herbicides or
pesticides will be in accordance with manufacturer’s recommendations and confined to
periods when the vegetation is not wet from rainfall or dew within a zone of 10m from
any watercourse.
15.3 Summary of Residual Impacts
15.3.1 Soils, Geology and Hydrogeology
• Residual impacts include the excavation and compaction of soil. Shallow excavation of
materials is required through out the area of the junction improvements for road regarding
and embankment construction.
• The sub-soil beneath embankments will be compacted to achieve the relevant engineering
design values prior to embankment construction. This compaction is a permanent impact.
• Residual impacts on the hydrogeology include the potential for groundwater
contamination during the operational phase. Although as the construction works will
generally result in a greater depth of covering over the bedrock aquifer than is currently
there, it could be considered that the works will reduce the vulnerability of the bedrock
aquifer.
• The proposed development will result in an impermeable surface being constructed over
the bedrock aquifer. This may have the effect of a minor reduction of groundwater
recharge to the aquifer.
15.3.2 Landscape and Visual
• The primary significant and negative visual impacts will be during the construction phase
and will be short term.
• Upon completion of the works the visual impact generally will be moderate and neutral
with a localised moderate and negative visual impact to the rear of the houses backing on
to the north-eastern portion of the overpass.
• The proposed scheme will be seen as a natural improvement to the existing road system,
improving traffic flow in the area and reducing the visual clutter, caused by traffic build
up, that exists at present at the junction.
15.3.3 Noise and Vibration
15.3.3.1 Construction Phase - Noise
• During the construction phase of the project there will be an impact on nearby residential
and business properties due to noise emissions from construction activities. The
application of the Noise and Vibration Management Plan and the Plan for Control of
Noise and Vibration will ensure that noise impact is kept to a minimum consistent with
efficient construction practices.
15.3.3.2 Operational Phase – Noise
December 2007 Page 245