Analysis and Ranking of the Acoustic Disturbance Potential of ...

Report No. 6945
BBN Systems and Technology Corporation
APPENDIX E:
ESTIMATED RECEIVED LEVEL SPECTRA FOR MAJOR NOISE SOURCES
OPERATING IN SELECTED OCS PLANNING AREAS
Transmission loss data and IFD Model predictions were used together with
source level spectra tb obtain estimated received level spectra for operation
of the major sound sources in the four selected OCS planning areas. The
sources were determined by the results of the SNC model analysis (Sec. 5.3).
Both actual and hypothetical sources are included. Range steps were selected
to obtain approximate 10 dB decrements in received level spectra. The
estimated statistical range of ambient noise levels for the areas are also
included to show the ranges at which the received levels approach expected
ambient levels. A criterion based on 1/3 octave band levels 30 dB above the
50%ile ambient noise spectrum is also shown. This criterion spectrum is
intended to provide an indication of the range at which sound levels from the
source may become significant with respect to potential behavioral response.
Since data for establishing behavioral response criteria for specific noise
sources are unavailable for most of the sources and species included in this
study, the 30 dB criterion is intended to provide a common reference for all
of the sources shown until more specific response data become available.
The following figures are presented to show received level spectra versus
range for selected sources in the four planning areas:
Fig. E.1.
Vibroseis Array in the Chukchi Sea, Winter
Fig. E.2. Icebreaker Operating in the Chukchi Sea, Winter
Fig. E.3.
Fig. E.4.
Icebreaker Operating in the Chukchi Sea, Summer
Air Gun Array (WESTERN POLARIS) Operating in the Chukchi Sea,
Summer
Fig. E.5. Drillship (EXPLORER 11) Operating in the Chikchi Sea, Summer
Fig. E.6. Dredge (AQUARIUS) Operating in the Chukchi Sea, Summer ,
Fig. E.7.
Fig. E.8.
Tug/Barge Operating in the Chukchi Sea, Summer
Twin Outdrive Operating in the Chukchi Sea, Summer