facilities renewal master plan - National Zoo - Smithsonian Institution

FACILITIES MASTER PLAN ENVIRONMENTAL ASSESSMENT
The National Zoo is proposing an incentive for employees to use public transportation
that could result in reduced vehicle trips by employees to the Zoo and therefore, reduce
emissions.
Overall, Alternatives A, B, and C would have minor short-term adverse impacts from
construction activities associated with exhibit and facilities renewal. Implementation of
Alternatives A, B, or C would not be expected to generate an increase in vehicular traffic,
change land use, or affect employment patterns at the National Zoo; therefore, no longterm
impact on air quality would occur.
Mitigation for the Preferred Alternative
Best management practices will be utilized during construction of individual projects to
avoid and/or minimize the release of airborne pollutants. Such practices could include,
but would not be limited to, the use of water to control airborne dust in active grading
areas and material stockpiles, and the use of temporary vegetative cover and/or barriers
on inactive areas. To the extent possible, commercial power will be used over portable
generators during construction of projects to reduce temporary impacts to air quality.
More detailed air quality mitigation will be prepared during the conceptual design phase
of individual projects.
A.6 Noise
The extent to which individuals are affected by noise is controlled by several factors,
including:
The duration and frequency of sound;
The distance between the sound source and the receptor;
The intervening natural or man-made barriers or structures; and
The ambient environment.
The “A-weighted” decibel (dBA) is a unit of measure used to express the relative
loudness of sounds in the air as perceived by the human ear. The dBA scale deemphasizes
the very low and the very high frequencies and emphasizes the middle
frequencies, thereby closely approximating the frequency response of the human ear.
Common noise sources and their sound levels are described in the table below.
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