Page 288 - Fluid Power Engineering

254 Chapter Twelve

impact on wildlife is not significant, then the permitting pro-
cesses is begun. If significant impacts are identified, then the
question that is addressed is: Can the impacts be mitigated? If
the answer is yes, then plans are developed to mitigate and the
permitting process is begun. After the permit is obtained, con-
struction can begin. A list of best management practices for
site development and construction are presented in the guide-
lines. These can ensure that the potential impact is minimized
during the construction phase.
Tier 4: Postconstruction fatality studies. This tier is performed
if required by any of the tier 1–3 studies. The activities per-
formed in this tier include search for bird and bat carcasses,
classify finding based on species, compare actual fatalities
with predicted, and analyze variation of fatalities based on
turbine location within the project site.
Tier 5: Other postconstruction studies. This tier is performed in
cases when (a) the actual fatalities are higher than predicted
in tier 3 and/or the mitigation strategies implemented are
ineffective, and (b) the fatalities measured in tier 4 are likely
to cause a significant impact on the population. This tier is
costly and should be performed in rare cases. The intent of
the recommended guideline is to ensure that tier 1–3 are done
with enough rigor that a project is not in a situation in which
tier 5 is required.
In order to perform preliminary wildlife assessments, few states in the
UnitedStatesprovideonlinetoolsthatprovideaninventoryofspecies.
The State of Illinois Department of Natural Resource has an online
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application, Ecological Compliance Assessment Tool (EcoCAT) , that
provides a list of protected natural resources in and around an area of
interest.

Noise from Wind Turbines
Noise is a form of pollution generated by turbines. However, the im-
pact of sound is limited to a few hundred meters from the base of a
turbine. Noise is generated in a turbine from two primary sources:
1. Aerodynamic interactions between the blades and wind. This
is the persistent “whoosh” sound as the blades slice the wind.
This is the dominant noise from a turbine.
2. Mechanical noise from different parts of the turbine, like gear-
box and generator.

Sound is a pressure wave. A unit of measure for sound is decibels.
Sound level is quantified as ten times the logarithm of the ratio of