environmental statement - Rotherham's Online Application for ...

„health effects arising from shadow flicker will not have the potential to
occur Unless the operating frequency of a particular turbine is between 2.5
and 30 hertz and all other pre-conditions for shadow flicker effects to occur
exist‟.
15.20 Consequently shadow flicker caused by this development is predicted to
have no adverse health effects.
CUMULATIVE IMPACTS
15.21 The potential for cumulative shadow flicker has been investigated. H3
Ulley Beeches is the only receptor which has the potential for shadow
flicker to occur from two turbines simultaneously. With the proposed
turbines having a flash rate below 0.7 Hz, a combined flash rate of 1.4Hz
for two turbines is well below the threshold of 3 Hz recommended by
Harding et al. (2008) for cumulative shadow flicker effects.
MITIGATION
15.22 There are no UK guidelines which quantify what exposure levels of
shadow flicker would be acceptable. Where shadow flicker is found to
cause a nuisance and form an unacceptable impact, mitigation measures
can be implemented in order to reduce the occurrence of shadow flicker.
Such measures include planting tree belts between the affected window
and the turbines; though as previously stated a number of tree lines
surround existing properties which have the potential to dissipate any
occurrence, and shutting down the turbines using turbine control systems
during periods when shadow flicker could theoretically occur. Any turbine
control system would be developed in conjunction with a detailed
monitoring programme and implemented subsequent to the granting of
planning permission.
15.23 No routine mitigation is proposed; this will be kept under review during the
operation of the scheme in case particular combinations of circumstances
arise that increase the potential for nuisance (particularly where rooms
affected are in regular occupancy and the effect proves to be a frequent
occurrence in reality). Where nuisance arises, mitigation measures can
be incorporated into the operation of the wind turbines to reduce the
instance of shadow flicker to lower levels.
SUMMARY OF EFFECTS
15.24 A shadow flicker assessment has been undertaken for seven buildings
within 1040m of the proposed turbine locations; the theoretical range of
effect. It has been shown that under worst case conditions, the maximum
theoretical occurrence of shadow flicker amounts to 126.9 hours per year,
experienced at Ulley Beeches. The second highest potential occurrence is
104.9 hours per year at Penny Hill Lane, however as previously shown this
has a far lesser potential occurrence when considering other factors such
as actual average hours of sunlight. It is important however to note that
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Penny Hill Wind Farm
Environmental Statement