Forthbank Wind Energy Development - Partnerships for Renewables

Forthbank Wind Energy Development
• crane hard standings; and
• cabling.
13.4.43 The following section identifies the potential effects that are likely to occur on the hydrological,
geological and hydrogeological environment during the operation of the proposed wind energy
development.
Potential Operational Effects on Hydrology
Chemical Pollution
13.4.44 The potential risk of pollution is substantially lower during the operational phase because of the
decreased levels of activity. The majority of potential pollutants will have been removed when
construction is complete; however, lubricants for turbine gearboxes, hydraulic oils and the
potential for possible fuel leaks from maintenance vehicles will remain. Such impacts are
considered to be of minor magnitude.
Erosion and Sedimentation
13.4.45 Levels of erosion and sedimentation will also be much lower than during construction as there
is unlikely to be excavations or bare exposed ground, following post construction restoration.
Some erosion and sedimentation is still possible on the site tracks, hardstandings and
drainage ditches as a result of scouring during extreme rainfall events. This can have a
detrimental effect on the ecology of aquatic plants, fish, and invertebrates. These impacts are
considered to be of a minor magnitude.
Impediments to Flows
13.4.46 During the operational phase, impediments to flows generally only arise should there be any
blockages to ditches and watercourses resulting from natural vegetation and erosion debris.
This could cause a localised flood risk to on-site operations should it occur. This is considered
to have a minor magnitude.
Modification of Surface Runoff
13.4.47 Modification of the surface hydrological regime of the site will occur as a result of the presence
of the proposed wind energy development infrastructure. There are potentially two aspects to
this, changes to the volume and changes to runoff rate. Drainage of site infrastructure will
result in increased time to peak and runoff volumes leading to a potential increase in the risk of
flooding in adjacent water bodies. This is considered to be of a moderate magnitude.
13.4.48 Drainage will be designed to attenuate flow and any discharges will be limited to the
predevelopment greenfield runoff rate. Table 13.10 below shows the calculated greenfield
runoff rates for each catchment containing site infrastructure, along with the anticipated level of
attenuation storage required to reduce drainage discharge to the pre development conditions.
November 2010 Chapter 13 Page 26
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