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Susitna‐Watana Hydroelectric Project Document
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Title:
Aesthetic resources study, Study plan Section 12.6, 2014 Study
Implementation Report SuWa 289
Author(s) – Personal:
Author(s) – Corporate:
AECOM
AEA‐identified category, if specified:
November 2015; Study Completion and 2014/2015 Implementation Reports
AEA‐identified series, if specified:
Series (ARLIS‐assigned report number):
Susitna-Watana Hydroelectric Project document number 289
Existing numbers on document:
Published by:
[Anchorage : Alaska Energy Authority, 2015]
Date published:
Main report: October 2015
Attachment 1: September 2015
Published for:
Alaska Energy Authority
Date or date range of report:
Volume and/or Part numbers:
Study plan Section 12.6
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Document type:
Pagination:
147 pages in various pagings
Related works(s):
Pages added/changed by ARLIS:
Notes:
Contents:
Main report
Attachment 1. Soundscape technical memorandum
All reports in the Susitna‐Watana Hydroelectric Project Document series include an ARLIS‐
produced cover page and an ARLIS‐assigned number for uniformity and citability. All reports
are posted online at http://www.arlis.org/resources/susitna‐watana/
Susitna-Watana Hydroelectric Project
(FERC No. 14241)
Aesthetic Resources Study
Study Plan Section 12.6
2014 Study Implementation Report
Prepared for
Alaska Energy Authority
Prepared by
AECOM
October 2015
2014 STUDY IMPLEMENTATION REPORT AESTHETIC RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page i October 2015
TABLE OF CONTENTS
1. Introduction ........................................................................................................................... 1
2. Study Objectives .................................................................................................................... 1
3. Study Area .............................................................................................................................. 1
4. Methods and Variances in 2014 ........................................................................................... 2
4.1. Viewshed Modeling ....................................................................................................... 3
4.1.1. Variances ................................................................................................................. 3
4.2. Identification of Analysis Locations .............................................................................. 3
4.2.1. Variances ................................................................................................................. 3
4.3. Baseline Data Collection ................................................................................................ 3
4.3.1. Variances ................................................................................................................. 3
4.4. Photosimulations ............................................................................................................ 3
4.4.1. Variances ................................................................................................................. 3
4.5. Soundscape Analysis ...................................................................................................... 3
4.5.1. Variances ................................................................................................................. 4
4.6. GIS Maps and Figures .................................................................................................... 4
4.6.1. Variances ................................................................................................................. 4
4.7. Assessment of Downriver Study Area ........................................................................... 4
4.7.1. Variances ................................................................................................................. 4
5. Results ..................................................................................................................................... 4
5.1. Aesthetics ....................................................................................................................... 4
5.1.1. Viewshed Modeling ................................................................................................ 4
5.1.2. Comprehensive Plan Review .................................................................................. 4
5.1.3. Landscape Character Types .................................................................................... 4
5.1.4. Field Investigation .................................................................................................. 5
5.1.5. Selection of Analysis Locations .............................................................................. 5
5.1.6. Summary of Analysis Locations ............................................................................. 5
5.1.7. Baseline Data Collection......................................................................................... 5
5.1.8. Photosimulations ..................................................................................................... 5
5.2. Soundscape ..................................................................................................................... 5
5.2.1. Review Documentation and Develop Data Needs .................................................. 5
5.2.2. Seasonal Surveys of Ambient Sound Levels .......................................................... 5
2014 STUDY IMPLEMENTATION REPORT AESTHETIC RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page ii October 2015
5.2.3. Modeling of Project Sound Levels ......................................................................... 5
5.3. Assessment of Downriver Study Area ........................................................................... 5
6. Discussion ............................................................................................................................... 6
6.1. Aesthetic Resources ....................................................................................................... 6
6.2. Soundscape ..................................................................................................................... 6
7. Conclusion .............................................................................................................................. 6
7.1. Decision Points from Study Plan .................................................................................... 6
8. Figures .................................................................................................................................... 8
LIST OF FIGURES
Figure 3-1. Aesthetics Resource Study Area .................................................................................. 8
ATTACHMENTS
Attachment 1: Soundscape Technical Memorandum
2014 STUDY IMPLEMENTATION REPORT AESTHETIC RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page iii October 2015
LIST OF ACRONYMS, ABBREVIATIONS, AND DEFINITIONS
Abbreviation Definition
AEA Alaska Energy Authority
CFR Code of Federal Regulations
DEM Digital Elevation Model
FERC Federal Energy Regulatory Commission
GIS Geographic Information System
ILP Integrated Licensing Process
ISR Initial Study Report
PRM Project River Mile
RSP Revised Study Plan
SPD Study Plan Determination
2014 STUDY IMPLEMENTATION REPORT AESTHETIC RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 1 October 2015
1. INTRODUCTION
This Aesthetic Resources Study, Section 12.6 of the Revised Study Plan (RSP) approved by the
Federal Energy Regulatory Commission (FERC) for the Susitna-Watana Hydroelectric Project,
FERC Project No. 14241, focuses on inventorying and documenting baseline aesthetic
conditions within the Aesthetic Resources Study Area and evaluating the potential effects to
aesthetic resources that may result from construction and operation of the proposed Project.
A summary of the development of this study, together with the Alaska Energy Authority’s
(AEA) implementation of it through the 2013 study season, appears in Part A, Section 1 of the
Initial Study Report (ISR) filed with FERC in June 2014. As required under FERC’s regulations
for the Integrated Licensing Process (ILP), the ISR describes AEA’s “overall progress in
implementing the study plan and schedule and the data collected, including an explanation of any
variance from the study plan and schedule.” (18 CFR 5.15(c)(1)).
Since filing the ISR in June 2014, AEA has continued to implement the FERC-approved plan for
the Aesthetic Resource Study. Progress included:
On October 23, 2014, AEA held an ISR meeting for the Aesthetic Resources Study.
As described in detail below, AEA completed the assessment of baseline soundscape for
the Study Area.
In furtherance of the next round of ISR meetings and FERC’s Study Plan Determination (SPD)
expected in 2016, this report describes AEA’s overall progress in implementing the Aesthetic
Resources Study during calendar year 2014. Rather than a comprehensive reporting of all field
work, data collection, and data analysis since the beginning of AEA’s study program, this report
is intended to supplement and update the information presented in the ISR for the Aesthetic
Resources Study through the end of calendar year 2014. It describes the methods and results of
the 2014 effort, and includes a discussion of the results achieved.
2. STUDY OBJECTIVES
The study objectives are established in RSP Section 12.6.1. The goals and objectives for the
Aesthetic Resources Study are to inventory and document baseline aesthetic (e.g., visual,
auditory) conditions within the Aesthetic Resources Study area and evaluate the potential effects
to aesthetic resources that may result from construction and operation of the proposed Project.
The analysis will focus on assessing these potential impacts and will help identify potential
design and other mitigation options.
3. STUDY AREA
Figure 3-1 shows the Aesthetic Resources Study area as established by RSP Section 12.6.3. The
study area was designed to be sufficient in size to address likely established indicators of change,
2014 STUDY IMPLEMENTATION REPORT AESTHETIC RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 2 October 2015
including potential direct and indirect effects to recreation, cultural resources, subsistence,
socioeconomics, geomorphology/ice processes, and riparian vegetation.
The Aesthetic Resources Study area was divided into primary and secondary study areas. The
primary study area is a 30-mile radius surrounding all Project components, including: the
proposed dam and camp facilities including construction sites; the reservoir, transmission
corridors, access road corridors, borrow sites, and rail sidings. The primary study area was
defined in Q1 2013 using viewshed models generated from the most current Project design
information at a resolution of a 10m Digital Elevation Model (DEM). At present, the analysis is
focused on the following broadly defined viewer areas:
The Susitna River corridor, downstream of Devils Canyon to Talkeetna
The Susitna River corridor, from Devils Canyon to the proposed dam site
The Susitna River, upstream of the proposed dam site to the upriver extent of the
inundation zone
Upland areas adjacent to the Susitna River, with emphasis on those areas within the
viewshed of the inundation zone, proposed access roads, and proposed transmission
corridors
Common air transportation routes used for transportation and recreational air tours
The secondary study area for this study includes all lands located between the Denali Highway,
south to the Glenn Highway and from the Richardson Highway, east to the mouth of the Susitna
River. This area will be evaluated using existing information to understand the distribution of
aesthetic resources within a larger geographic context.
The Study Plan noted that the aesthetics resource study area could be adjusted during the next
study year to include areas within the river corridor located downriver of Talkeetna, if 2013
studies in the lower reach indicate a possible Project-related effect on aesthetic resources in this
area.
As described in Part C, Section 7.1.2 of the ISR filed with FERC in June 2014, AEA added the
Denali East Option road and transmission corridor to the study area. Consequently, the study
area was changed from that described in the RSP (Section 12.6.3). The modified study area
showing the Denali East Option is depicted on Figure 7.1-1 and Figure 7.1-2. Figure 7.1-1
illustrates the project viewshed (primary study area), with the viewshed for the Denali East
Option overlaid.
4. METHODS AND VARIANCES IN 2014
The following section provides a brief summary of the tasks performed, the methods utilized,
and any variances from the methods described in the Study Plan (Section 12.6.3 of RSP 12.6).
2014 STUDY IMPLEMENTATION REPORT AESTHETIC RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 3 October 2015
4.1. Viewshed Modeling
The methods to prepare viewshed models were previously discussed in the ISR Section 12.6.3
filed in June, 2014.
4.1.1. Variances
No additional work was performed in 2014, and thus there were no variances to the methods
described in Section 12.6.3 of the RSP 12.6 for 2013 and 2014.
4.2. Identification of Analysis Locations
The methods to identify analysis locations were previously discussed in the ISR Section 12.6.3
filed in June, 2014.
4.2.1. Variances
No additional work was performed in 2014, and thus there were no variances to the methods
described in Section 12.6.3 of the RSP 12.6 for 2013 and 2014.
4.3. Baseline Data Collection
The methods used for baseline data collection were previously discussed in the ISR Section
12.6.3 filed in June, 2014.
4.3.1. Variances
No additional work was performed in 2014, and thus there were no variances to the methods
described in Section 12.6.3 of the RSP 12.6 for 2013 and 2014.
4.4. Photosimulations
The methods used for photosimulations were previously discussed in the ISR Section 12.6.3 filed
in June, 2014.
4.4.1. Variances
No additional work was performed in 2014, and thus there were no variances to the methods
described in Section 12.6.3 of the RSP 12.6 for 2013 and 2014.
4.5. Soundscape Analysis
The methods used for the soundscape analysis were previously discussed in the ISR Section
12.6.3 filed in June, 2014.
2014 STUDY IMPLEMENTATION REPORT AESTHETIC RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 4 October 2015
4.5.1. Variances
No variances to the methods described in Section 12.5.4 of the RSP 12.5 for 2013 and 2014
occurred for work completed on the soundscape analysis during 2014.
4.6. GIS Maps and Figures
The methods used for geographic information system (GIS) maps and figures were previously
discussed in the ISR Section 12.6.3 filed in June, 2014.
4.6.1. Variances
No additional work was performed in 2014, and thus there were no variances to the methods
described in Section 12.6.3 of the RSP 12.6 for 2013 and 2014.
4.7. Assessment of Downriver Study Area
The methods used for the assessment of the downriver study area were previously discussed in
the ISR Section 12.6.3 filed in June, 2014.
4.7.1. Variances
No additional work was performed in 2014, and thus there were no variances to the methods
described in Section 12.6.3 of the RSP 12.6 for 2013 and 2014.
5. RESULTS
This section summarizes the aesthetic resources data from the 2013 and 2014 study season
collected pursuant to Section 12.6.3 of the RSP.
5.1. Aesthetics
The results of the aesthetic resources study have been previously report in June 2014 in ISR 12.6.
5.1.1. Viewshed Modeling
No additional work was performed in 2014 for viewshed modelling.
5.1.2. Comprehensive Plan Review
No additional work was performed in 2014 for the comprehensive plan review.
5.1.3. Landscape Character Types
No additional work was performed in 2014 for the landscape character types.
2014 STUDY IMPLEMENTATION REPORT AESTHETIC RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 5 October 2015
5.1.4. Field Investigation
No additional filed investigations were performed in 2014.
5.1.5. Selection of Analysis Locations
No additional work was performed in 2014 for the selection of analysis locations. ISR 12.6 of
June 2014 presents aesthetic resource data collected from within the Aesthetic Resources Study
Area.
5.1.6. Summary of Analysis Locations
No additional work was performed in 2014 for the summary of analysis locations. ISR 12.6
summarizes analysis locations within the Aesthetic Resources Study Area.
5.1.7. Baseline Data Collection
No additional baseline data was collected in 2014. ISR 12.6 of June 2014 presents aesthetic
resource data collected from within the Aesthetic Resources Study Area.
5.1.8. Photosimulations
No additional work was performed for photosimulations in 2014.
5.2. Soundscape
5.2.1. Review Documentation and Develop Data Needs
No additional document review and data needs development was completed in 2014.
5.2.2. Seasonal Surveys of Ambient Sound Levels
No additional seasonal surveys of ambient sounds levels were completed in 2014. The results of
the 2013 studies were analyzed; a summary is provided in Attachment 1.
5.2.3. Modeling of Project Sound Levels
No modelling of project sounds levels was completed in 2014.
5.3. Assessment of Downriver Study Area
No assessment of the downriver study areas was completed in 2014.
2014 STUDY IMPLEMENTATION REPORT AESTHETIC RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 6 October 2015
6. DISCUSSION
6.1. Aesthetic Resources
A discussion of the aesthetic resources study is presented in the June 2014 ISR 12.6 reports. As
reported in Part C of the June 2014 ISR the following tasks still remain to be completed in the
Aesthetic Resources Study:
Develop viewshed models for pre- and post-Project conditions of the inundation zone of
the Susitna River to depict expected changes in viewshed areas (RSP Section 12.6.4).
Baseline data collection of basic landscape components (RSP Section 12.6.4).
Produce photosimulations to illustrate the expected visibility of Project components (RSP
Section 12.6.4).
6.2. Soundscape
A discussion of the soundscape study is presented in Attachment 1. All components of the
soundscape analysis task have been completed.
7. CONCLUSION
From 2013 to 2014, AEA completed the baseline soundscape assessment, including review,
compilation and interpretation of baseline sound data collected during the 2013 field season. This
work on the Aesthetics Resources Study successfully meets the study objectives in the FERC-
approved Study Plan. The results of this Aesthetics Resources Study component are reported
herein and in the June 2014 ISR.
Implementation of the Aesthetic Resources Study is planned, with no modification of the
methods in the FERC-approved Study Plan. This study is interrelated with the Recreation
Resources Study (Study 12.5) and Recreation River Flow and Access Study (Study 12.7). AEA
expects the approved Study Plan objectives for both this study and Studies 12.5 and 12.7 will be
achieved, as AEA proposes no modifications to the methods of this study. The results of this
study will be reported in the USR.
7.1. Decision Points from Study Plan
In 2013 AEA collected information on river recreation use and experience and coordinated with
the study teams for the Instream Flow Study (Study 8.5), Ice Processes in the Susitna River
Study (Study 7.6), Geomorphology Study (Study 6.5), River Recreation and Flow Study (Study
12.7), and Aesthetics Resources Study (Study 12.6). The first year results from these studies
indicate that Project operations will only slightly influence river flows and river morphology,
such that projected changes will be within the range of normal variation downstream of the Parks
Highway Bridge (PRM 88.9) under existing, baseline conditions, and therefore will not
adversely affect aesthetic conditions in the lower river. These data, which are summarized in
2014 STUDY IMPLEMENTATION REPORT AESTHETIC RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 7 October 2015
Section 7.1.1. of Part C of the June 2014 ISR, support AEA’s decision not to extend the
aesthetics studies below the George Parks Highway Bridge.
2014 STUDY IMPLEMENTATION REPORT AESTHETIC RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 8 October 2015
8. FIGURES
Figure 3-1. Aesthetics Resource Study Area
2014 STUDY IMPLEMENTATION REPORT AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 October 2015
ATTACHMENT 1 – SOUNDSCAPE TECHNICAL MEMORANDUM
Susitna-Watana Hydroelectric Project
(FERC No. 14241)
Aesthetics Resources Study
Study Plan Section 12.6
Soundscape Technical Memorandum
Prepared for
Alaska Energy Authority
Prepared by
AECOM
September 2015
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page i September 2015
TABLE OF CONTENTS
1. Introduction .............................................................................................................................1
2. Study Objectives .....................................................................................................................1
3. Study Area ...............................................................................................................................2
4. Methods ...................................................................................................................................4
4.1. Seasonal Surveys of Ambient Sound Levels ..................................................................4
4.1.1. Site Selection .......................................................................................................... 4
4.1.2. Equipment ............................................................................................................... 5
4.1.3. Data Collection ....................................................................................................... 9
4.1.4. Data Analysis ........................................................................................................ 11
4.2. Variances .......................................................................................................................13
5. Results ....................................................................................................................................14
5.1. Review Documentation and Develop Data Needs ........................................................14
5.2. Seasonal Surveys of Ambient Sound Levels ................................................................15
5.2.1. Winter Long-Term Acoustic Monitoring .............................................................. 19
5.2.2. Spring Long-Term Acoustic Monitoring .............................................................. 27
5.2.3. Summer Long-Term Acoustic Monitoring ........................................................... 40
5.2.4. Fall Season Long-Term Acoustic Monitoring ...................................................... 54
6. Discussion ..............................................................................................................................67
6.1. Review Documentation .................................................................................................67
6.2. Seasonal Surveys of Ambient Sound Levels ................................................................67
6.3. Variances .......................................................................................................................69
7. References ..............................................................................................................................70
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page ii September 2015
LIST OF TABLES
Table 4-1. Long-Term (LT) Soundscape Monitoring Equipment Roster (per Deployment) ..........6
Table 4-2. 2013 Long-Term (LT) Outdoor Ambient Sound Pressure Level (Lp) Monitoring
Locations ................................................................................................................................10
Table 4-3. Natural Sound Disturbance Classification ....................................................................13
Table 5-1. Long-Term Sound Monitor Winter LT1 Summary ......................................................20
Table 5-2. Long-Term Sound Monitor Winter LT2 Summary ......................................................22
Table 5-3. Long-Term Sound Monitor Winter LT4 Summary ......................................................24
Table 5-4. Long-Term Sound Monitor Winter LT5 Summary ......................................................25
Table 5-5. Long-Term Sound Monitor Winter LT7 Summary ......................................................27
Table 5-6. Long-Term Sound Monitor Spring LT1 Summary ......................................................28
Table 5-7. Long-Term Sound Monitor Spring LT2 Summary ......................................................30
Table 5-8. Long-Term Sound Monitor Spring LT3 Summary ......................................................32
Table 5-9. Long-Term Sound Monitor Spring LT4 Summary ......................................................33
Table 5-10. Long-Term Sound Monitor Spring LT5 Summary ....................................................35
Table 5-11. Long-Term Sound Monitor Spring LT6 Summary ....................................................36
Table 5-12. Long-Term Sound Monitor Spring LT7 Summary ....................................................38
Table 5-13. Long-Term Sound Monitor Spring LT9 Summary ....................................................40
Table 5-14. Long-Term Sound Monitor Summer LT1 Summary .................................................41
Table 5-15. Long-Term Sound Monitor Summer LT3 Summary .................................................43
Table 5-16. Long-Term Sound Monitor Summer LT4 Summary .................................................45
Table 5-17. Long-Term Sound Monitor Summer LT5 Summary .................................................47
Table 5-18. Long-Term Sound Monitor Summer LT6 Summary .................................................48
Table 5-19. Long-Term Sound Monitor Summer LT7 Summary .................................................50
Table 5-20. Long-Term Sound Monitor Summer LT8 Summary .................................................52
Table 5-21. Long-Term Sound Monitor Summer LT9 Summary .................................................54
Table 5-22. Long-Term Sound Monitor Fall LT1 Summary .........................................................55
Table 5-23. Long-Term Sound Monitor Fall LT2 Summary .........................................................57
Table 5-24. Long-Term Sound Monitor Fall LT3 Summary .........................................................58
Table 5-25. Long-Term Sound Monitor Fall LT4 Summary .........................................................60
Table 5-26. Long-Term Sound Monitor Fall LT5 Summary .........................................................61
Table 5-27. Long-Term Sound Monitor Fall LT7 Summary .........................................................63
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page iii September 2015
Table 5-28. Long-Term Sound Monitor Fall LT8 Summary .........................................................64
Table 5-29. Long-Term Sound Monitor Fall LT9 Summary .........................................................66
LIST OF FIGURES
Figure 3-1. Aesthetics Resource Study Area ...................................................................................3
Figure 4-1. Typical Components of a Long-Term (LT) Monitoring Deployment ..........................7
Figure 4-2. Typical Components of a Short-Term (ST) Lp Measurement Setup .............................8
Figure 4-3. Plot of A-Weighted One-Third Octave Spectra Lp Versus Time: Mechanized Sound
(Motorized Vehicle) and Biophony (Birdsong), Spring Season ............................................12
Figure 5-1. Soundscape Locations - Long Term ...........................................................................17
Figure 5-2. Photo of Long-Term Sound Monitor Winter LT1 Location .......................................20
Figure 5-3. Photo of Long-Term Sound Monitor Winter LT2 Location .......................................22
Figure 5-4. Photo of Long-Term Sound Monitor Winter LT4 Location .......................................24
Figure 5-5. Photo of Long-Term Sound Monitor Winter LT5 Location .......................................25
Figure 5-6. Photo of Long-Term Sound Monitor Winter LT7 Location .......................................26
Figure 5-7. Photo of Long-Term Sound Monitor Spring LT1 Location .......................................28
Figure 5-8. Photo of Long-Term Sound Monitor Spring LT2 Location .......................................30
Figure 5-9. Photo of Long-Term Sound Monitor Spring LT3 Location .......................................31
Figure 5-10. Photo of Long-Term Sound Monitor Spring LT4 Location .....................................33
Figure 5-11. Photo of Long-Term Sound Monitor Spring LT5 Location .....................................34
Figure 5-12. Photo of Long-Term Sound Monitor Spring LT6 Location .....................................36
Figure 5-13. Photo of Long-Term Sound Monitor Spring LT7 Location .....................................38
Figure 5-14. Photo of Long-Term Sound Monitor Spring LT9 Location .....................................39
Figure 5-15. Photo of Long-Term Sound Monitor Summer LT1 Location ...................................41
Figure 5-16. Photo of Long-Term Sound Monitor Summer LT3 Location ...................................43
Figure 5-17. Photo of Long-Term Sound Monitor Summer LT4 Location ...................................45
Figure 5-18. Photo of Long-Term Sound Monitor Summer LT5 Location ...................................46
Figure 5-19. Photo of Long-Term Sound Monitor Summer LT6 Location ...................................48
Figure 5-20. Photo of Long-Term Sound Monitor Summer LT7 Location ...................................50
Figure 5-21. Photo of Long-Term Sound Monitor Summer LT8 Location ...................................52
Figure 5-22. Photo of Long-Term Sound Monitor Summer LT9 Location ...................................53
Figure 5-23. Photo of Long-Term Sound Monitor Fall LT1 Location ..........................................55
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page iv September 2015
Figure 5-24. Photo of Long-Term Sound Monitor Fall LT2 Location ..........................................56
Figure 5-25. Photo of Long-Term Sound Monitor Fall LT3 Location ..........................................58
Figure 5-26. Photo of Long-Term Sound Monitor Fall LT4 Location ..........................................59
Figure 5-27. Photo of Long-Term Sound Monitor Fall LT5 Location ..........................................61
Figure 5-28. Photo of Long-Term Sound Monitor Fall LT7 Location ..........................................62
Figure 5-29. Photo of Long-Term Sound Monitor Fall LT8 Location ..........................................64
Figure 5-30. Photo of Long-Term Sound Monitor Fall LT9 Location ..........................................65
APPENDICES
Appendix A. Glossary of Terms
Appendix B. Spectrographs
Appendix C. Graphs of Long-Term Monitoring Data
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page v September 2015
LIST OF ACRONYMS, ABBREVIATIONS, AND DEFINITIONS
Abbreviation Definition
%TA Percent-Time Audible
AEA Alaska Energy Authority
ASAG Acoustic Sampling and Analysis Guide
CFR Code of Federal Regulations
DAR Digital Audio Recorder
dBA A-Weighted Decibel
DNP Denali National Park
EPA U.S. Environmental Protection Agency
FERC Federal Energy Regulatory Commission
GPS Global Positioning System
Hz Hertz
ISO International Organization of Standardization
L10 Sound Level Exceeded 10 Percent of the Time
L50 Median Sound Level
L90 Background Sound Level
Ldn Day-Night Sound Level
Leq Equivalent Sound Level
Lp or SPL Sound Pressure Level
LD Larson-Davis
LT Long-Term (≥ 24-Hour Period)
NIST National Institute of Standards and Technology
NPS U.S. National Park Service
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page vi September 2015
Abbreviation Definition
NVLAP National Voluntary Laboratory Accreditation Program
RSP Revised Study Plan
SPD Study Plan Determination
SPL or Lp Sound Pressure Level
SLM Sound Level Meter
ST Short-Term (< 24-Hour Period)
USC United States Code
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 1 September 2015
1. INTRODUCTION
On December 14, 2012, Alaska Energy Authority (AEA) filed with the Federal Energy Regulatory
Commission (FERC or Commission) its Revised Study Plan (RSP) for the Susitna-Watana
Hydroelectric No. 14241 (Project), which included 58 individual study plans (AEA 2012).
Included within the RSP was the Aesthetic Resources Study, Section 12.6. RSP Section 12.6
focuses on inventorying and documenting baseline aesthetic conditions within the Aesthetic
Resources Study Area and evaluating the potential effects to aesthetic resources that may result
from construction and operation of the proposed Project. RSP Section 12.6 provided provides
goals, objectives, and proposed methods for aesthetic resources data collection and analysis.
On February 1, 2013, FERC staff issued its study plan determination (February 1 SPD) for 44 of
the 58 studies, approving 31 studies as filed and 13 with modifications. RSP Section 12.6 was one
of the 13 approved with modifications. In its February 1 SPD, FERC recommended the following:
We recommend that AEA modify the Aesthetic Resources Study Plan as follows:
Conduct surveys of ambient sound levels in all four seasons.
Include in the initial study report any proposed modifications to the study plan
based on the first year’s data on the lower river uses, hydrology, and ice processes.
This 2014 End of Year Report on Aesthetic Resources Study has been prepared in accordance with
FERC’s Integrated Licensing Process regulations and details AEA’s status in implementing the
study, as set forth in the FERC-approved RSP and as modified by FERC’s February 1 SPD
(referred to herein as the “Study Plan”).
2. STUDY OBJECTIVES
The study objectives are established in RSP Section 12.6.1. The goals and objectives for the
Aesthetic Resources Study are to inventory and document baseline aesthetic (e.g., visual, auditory)
conditions within the Aesthetic Resources Study Area and evaluate the potential effects to aesthetic
resources that may result from construction and operation of the proposed Project. The analysis
will focus on assessing these potential impacts and will help identify potential design and other
mitigation options.
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 2 September 2015
3. STUDY AREA
Figure 3-1 shows the Aesthetic Resources Study Area as established by RSP Section 12.6.3. The
Study Area was designed to be sufficient in size to address likely established indicators of change,
including potential direct and indirect effects to recreation, cultural resources, subsistence,
socioeconomics, geomorphology/ice processes, and riparian vegetation.
The Aesthetic Resources Study Area was divided into primary and secondary study areas. The
primary Study Area is a 30-mile radius surrounding all Project components, including the proposed
dam and camp facilities, including construction sites; the reservoir; transmission corridors; access
road corridors; borrow sites; and rail sidings. The primary Study Area was defined in Q1 2013
using viewshed models generated from the most current Project design information at a resolution
of a 10-meter Digital Elevation Map. At present, the analysis is focused on the following broadly
defined viewer areas:
The Susitna River corridor, downstream of Devils Canyon to Talkeetna
The Susitna River corridor, from Devils Canyon to the proposed dam site
The Susitna River, upstream of the proposed dam site to the upriver extent of the inundation
zone
Upland areas adjacent to the Susitna River, with emphasis on those areas within the
viewshed of the inundation zone, proposed access roads, and proposed transmission
corridors
Common air transportation routes used for transportation and recreational air tours
As explained in Part C of the ISR, Section 1.4, when the ISR was filed AEA explained that it had
decided to pursue the study of an additional alternative north-south corridor alignment for
transmission and access from the dam site to the Denali Highway. Referred to the “Denali East
Option,” these areas were added to the study area for this study beginning in 2014.
In addition, Section 1.4 of the ISR noted that AEA was considering the possibility of eliminating
the Chulitna Corridor from further study. In September 2014, AEA filed with FERC a formal
proposal to implement this change. Thus, this report reflects a change in the study area to no
longer include the Chulitna Corridor.
The secondary Study Area for this study includes all lands located between the Denali Highway,
south to the Glenn Highway, and from the Richardson Highway, east to the mouth of the Susitna
River. This area will be evaluated using existing information to understand the distribution of
aesthetic resources within a larger geographic context.
The Study Plan noted that the Aesthetics Resource Study Area could be adjusted during the next
study year to include areas within the river corridor located downriver of Talkeetna, if 2013 studies
in the lower reach indicate a possible Project-related effect on aesthetic resources in this area.
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 3 September 2015
Figure 3-1. Aesthetics Resource Study Area
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 4 September 2015
4. METHODS
AEA implemented the methods for the soundscape analysis described in Section 12.6.4 of with no
variances. Data was collected to characterize the existing ambient sound environment in the Study
Area to provide a baseline for assessment of potential change as a result of construction and
operational activities of the proposed Project. Methods presented in this section tier from Section
4.5.2 of ISR 12.6.Review Documentation
Relevant Project data contained in AEAs Pre-Application Document (AEA 2011) was reviewed
for information on potential noise sources associated with construction and operating of the
proposed Project. A regulatory review was completed to determine relevant management
framework with a nexus to the proposed Project. Analysis locations were selected based on
information gleaned from this review, and through coordination with the visual resources
assessment (Section 4.2 of the Initial Study Report), Recreation Resources Study (Study 12.5), and
the River Recreation Flow and Access Study (Study 12.7).
4.1. Seasonal Surveys of Ambient Sound Levels
AEA implemented seasonal surveys of ambient sound levels per methods described in the Study
Plan with no variances.
Ambient sound level measurements were collected with the goal of establishing baseline
soundscape data. Outdoor ambient sound level survey methods followed the U.S. National Park
Service (NPS) Acoustic Sampling and Analysis Guide (ASAG; NPS 2008) and methods described
in the Denali National Park (DNP) Acoustic Monitoring Report (NPS 2009). Sound measurements
included (1) unattended long-term (LT) monitors deployed for a minimum of 24 continuous hours
and up to a single week, and (2) attended short-term (ST) monitors deployed for 15-20 minutes
duration during day and night conditions. Perceived and identifiable sources of sound, such as bird
calls, aircraft, or passing train or vehicle traffic, and the conditions during which they occur, were
documented as part of the baseline data collection effort. This survey was conducted across four
discrete survey periods corresponding with winter, spring, summer, and fall of 2013.
4.1.1. Site Selection
Landscapes sharing similar characteristics such as vegetative cover, terrain features, elevation, and
meteorology are assumed to have similar sources of natural sound (both geophony and biophony)
and inherent sound attenuating properties (e.g., linearly occluding hill crests or ridgelines,
acoustically absorptive foliage and fallen snow, etc.). Hence, valid sound measurements from a
small sample quantity of outdoor ambient sound monitoring locations in shared settings are
considered representative of the outdoor sound environment of a much larger area, or multiple
areas that also share these geographic parameters and acoustical contributors.
Ambient sound pressure level (SPL or Lp) measurements and digital audio recordings were taken
in the Study Area. These measurements are used to characterize the audibility and frequency of
man-made disturbance to the natural soundscape in the Project area. Unattended LT measurements
were recorded at representative noise-sensitive receivers, recreation sites, and locations addressing
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 5 September 2015
the geographic diversity of the Study Area. Attended ST sound measurements were recorded at
similar locations and used to further characterize the affected environment by expanding the
geographic area where measurements were recorded. Observations of perceived and identifiable
sources of sound and the conditions during which they occur were documented as part of these
field surveys. Soundscape surveys were conducted during each of the four seasons: winter (March
7-18, 2013), spring (May 18-30, 2013), summer (July 12-20, 2013), and fall (September 7-14,
2013). To the extent practicable, surveys were implemented at the same geographic location across
multiple seasons.
Target locations for unattended LT monitoring stations were planned prior to each seasonal survey.
In some cases, these survey locations coincided with Key Observation Points used in the Project’s
visual resource assessment. Final LT monitor installation locations were determined based on site-
specific field conditions such as topography, helicopter access, and vegetative cover.
4.1.2. Equipment
Each LT monitor included a standard “831H” kit containing items listed in Table 4-1. Figure 4-1
provides a photograph of a typical LT monitor. The primary component of the Lp monitoring
system, the Larson-Davis (LD) Model 831, is the same ANSI S1.4-1983 (R2006) Type 1 sound
level meter (SLM) recommended for usage by the NPS ASAG. The SLM and its key components
(i.e., microphone and pre-amplifier) were factory calibrated, and thus consistent with the NPS
ASAG requiring the SLM system be calibrated annually by an International Organization of
Standardization (ISO) 17025 certified, National Voluntary Laboratory Accreditation Program
(NVLAP) accredited, and/or other National Institute of Standards and Technology (NIST)-
traceable acoustical calibration facility.
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 6 September 2015
Table 4-1. Long-Term (LT) Soundscape Monitoring Equipment Roster (per Deployment)
Item Quantity
Larson Davis (LD) Model 831 Sound Level Meter (SLM) 1
LD EXC020 Preamp Extension Cable 1
LD 377B02 Type 1 Microphone 1
LD PRM831 Preamplifier 1
Vaisala WXT520 Weather Transmitter 1
Environmental Shroud (Windscreen and Bird Spikes) 1
Heavy Duty Tripod 1
Adapters for Preamp/Microphone and Weather Transmitter 3
1/8" to 1/16" Audio Cable (Mono, Male-Male) 1
Roland R-05 Digital Audio Recorder (DAR) 1
60Ah 3.4v LiFePO4 Battery (For DAR) 1
21Ah 12-volt Lead-Acid Battery (For SLM and WXT520) 2
Power Cables for DAR, SLM, and WXT520 3
Weather Data Cable 1
Serial to USB Adapter 1
Guy Wire (Paracord) 3
MSR Groundhog Tent Stakes 3
Pelican Case (1170) - Dedicated DAR Battery Casing 1
Pelican Large Case - Housing SLM, DAR, and Lead-Acid Batteries 1
Master Lock Padlock (For Pelican Case) 1
Cable Loom (Conduit) 2
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 7 September 2015
Figure 4-1. Typical Components of a Long-Term (LT) Monitoring Deployment
Audio recording was performed with the following components: One Roland R-05 digital audio
recorder (DAR) outfitted with a 1/8” to 1/16” male-to-male monophonic audio cable to transmit
signal from the SLM to the DAR. A porous open-cell foam windscreen was installed over the SLM
microphone in the form of an environmental shroud with bird spikes. Digital audio was recorded
onto a 16 GB Secure Digital memory card.
The unit was powered by a custom-built power cable attached to a 60Ah 3.4v LiFePO4 battery.
While the LD 831 (SLM) and R-05 (DAR) each had separate dedicated power supplies, the R-05
received audio signal directly from the SLM. Hence, if the SLM were to deplete the charge in its
external battery, it would result in an automatic discontinuation of signal to the R-05. If, on the
SLM Microphone
Environmental
Shroud
Weather
Transmitter
Tripod Adapters
Large Case (SLM)
Small Case (DAR
Batt.)
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 8 September 2015
other hand, the R-05 were to exhaust its power supply, the SLM would continue to function as
allowed by its separate dedicated power supply.
A LD 200 Calibrator was used to field-check SLM calibration prior to, and upon completion of,
LT Lp monitoring. The LD 200 Calibrator is ANSI S1.4-1983 (R2006) and IEC 60942:2003 Class
1 performance rated and compatible with the NPS ASAG. The calibrator is factory-calibrated
annually.
The Vaisala WXT520 weather transmitter recorded wind speed and direction, temperature, relative
humidity, and precipitation rates and accumulation. This site-specific meteorological data were
not recorded consistently across all LT sites, either due to the weather transmitter not being
installed or problems relating to power supply and/or interface with the SLM.
The ST monitors consisted of a tripod-mounted LD 831 SLM (Figure 4-2). The ST SLMs were
factory calibrated as described for the LT SLMs. A hand-held WeatherHawk Skymaster SM-28
wind/weather meter was used to measure and collect air temperature, relative humidity, barometric
pressure, and average wind speed at each ST measurement location.
Figure 4-2. Typical Components of a Short-Term (ST) Lp Measurement Setup
Sound Level Meter
(SLM)
SLM microphone
within 3.5”
diameter
windscreen
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 9 September 2015
4.1.3. Data Collection
4.1.3.1. Long-Term Monitoring
Continuous, A-weighted Lp and unweighted, one-third octave band spectra from 20 to 20,000
Hertz (Hz) were collected at 1-second intervals (1-second Leq). The SLMs were set to operate with
“fast” collection, which represents a 0.125 second time constant. Wind speed, temperature and
relative humidity data were collected by the Vaisala WXT520 weather transmitter, with its data
collection controlled and logged by the on-board LD 831 SLM software and user settings.
Continuous DAR data were collected by the Roland R-05. Data were stored as multi-hour (up to
262 MB size) MPEG-1 Audio Layer III (MP3) format files.
The LT monitors were left unattended to record Lp and DAR data at survey locations for a
maximum of 1 week. The duration of up to 1 week was selected based on the following factors:
External power (i.e., the 12-volt batteries) provided as part of the standard “831H” kits was
expected to supply adequate charge for up to a week, depending on field conditions such
as ambient air temperature. Supplemental sources of power, such as solar panels, were not
elected for use due to logistical concerns such as size, weight, setup time, and available
maximum helicopter load.
One week, if assumed typical of several weeks during a monitored season, would comprise
a sequence of diurnal cycles that exhibit varying Lp and DAR data that correspond with
likely changes in acoustical contributors (e.g., road or rail traffic) due to the day of the
week. For instance, Lp measured on Saturday and Sunday at a location might demonstrate
greater contribution from nearby highway traffic noise—if such highway traffic volumes
were indeed higher during these weekend days than during Monday through Friday dates
of the monitored week. If the measured Lp on a Saturday is dominated by such highway
traffic noise, a subsequent Saturday within the same season would likely result in similar
measured Lp at the same monitoring location.
In practice, LT monitoring duration depended on external battery performance under the field
conditions. Generally, Lp and DAR data were successfully measured and collected for a minimum
of one completed diurnal cycle (24 continuous hours). Identification of audible acoustical
contributors to the outdoor ambient Lp and digital audio was performed after the completion of
fieldwork.
A minimum of four digital photographs corresponding to the four cardinal directions of each LT
monitoring setup were taken at each site. As part of permit compliance, several photographs were
also taken of LT monitor locations prior to and after disassembly to document local site conditions
before and after the survey period.
4.1.3.2. Short-Term Monitoring
Continuous, A-weighted Lp and unweighted, one-third octave band spectra from 20 to 20,000 Hz
were collected at 1-second intervals (1-second Leq) and tagged to specific time periods. The SLMs
were set to operate with “fast” collection, which represents a 0.125 second time constant. The
study team limited their movements and other actions (e.g., speech) while the SLM was measuring
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 10 September 2015
and collecting data. During Lp measurement and data collection by the activated SLM, field
conditions and acoustical contributors were recorded. Digital photographs of each ST tripod-
mounted SLM setup, corresponding approximately with the four cardinal directions, were taken at
each site.
LT and ST acoustic monitoring systems were deployed at 23 locations within the Study Area over
the four surveys seasons of 2013. Of these, seven LT positions were co-located, representing Lp
and DAR data collection at the same location across more than one season.
The data from co-located LT positions allowed for comparison of soundscapes and underlying
acoustical contributors across seasons. Data collection included a variety of acoustical metrics and
statistical values, such as existing ambient equivalent continuous sound level (Leq), and percent
time audible (%TA). Counts and post-measurement classification of natural and anthropogenic
events were developed by attentive listening and visual review of acoustical spectrograms. The LT
systems operated for a minimum of 24 hours, and up to 9 days, during which 1-second Lp and
digital audio were recorded. Table 4-2 provides LT measurement location information, including
elevation, global positioning system (GPS) geographic coordinates, and Lp data collection period.
Table 4-2. 2013 Long-Term (LT) Outdoor Ambient Sound Pressure Level (Lp) Monitoring Locations
Site ID Elevation (ft) Latitude Longitude Sampling Period (mm/dd)
Winter LT1 2,600 63.36646 -148.35935 03/07 - 03/12
Winter LT2 2,600 63.28942 -148.06701 03/07 - 03/12
Winter LT4 2,250 62.83047 -148.66463 03/08 - 03/11
Winter LT5 2,250 62.84934 -149.09233 03/08-03/15
WinterLT7 3,350 63.17352 -148.26231 03/11 - 03/18
Spring LT1 2,500 62.62237 -150.09857 05/18 - 05/24
Spring LT2 800 62.78604 -149.65572 05/18 - 05/24
Spring LT3 3,230 62.81964 -149.75472 05/20 - 05/27
Spring LT4 2,400 62.84393 -149.11560 05/20 - 05/30
Spring LT5 2,200 62.83000 -148.65740 05/23 - 05/29
Spring LT6 2,515 62.86830 -148.25330 05/23 - 05/31
Spring LT7 2,410 63.39105 -148.56028 05/21 - 05/26
Spring LT9 2,800 62.67589 -147.52700 05/23 - 05/30
Summer LT1 2,500 62.62237 -150.09857 07/12 - 07/19
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 11 September 2015
Site ID Elevation (ft) Latitude Longitude Sampling Period (mm/dd)
Summer LT3 3,500 63.18611 -148.27378 07/12 - 07/19
Summer LT4 2,800 62.88214 -148.37250 07/12 - 07/19
Summer LT5 2,400 62.76392 -148.41756 07/12 - 07/20
Summer LT6 2,200 62.83011 -148.65817 07/12 - 07/19
Summer LT7 3,200 62.86900 -148.70400 07/12 - 07/19
Summer LT8 2,630 62.84956 -149.09381 07/12- 07/20
Summer LT9 3,250 62.82242 -149.76122 07/12 - 07/18
Fall LT1 3,250 62.82242 -149.76122 09/07 - 09/09
Fall LT2 2,450 62.70147 -147.53439 09/07 - 09/09
Fall LT3 3,300 63.18611 -148.27378 09/07 - 09/09
Fall LT4 2,800 62.88214 -148.37250 09/07 - 09/09
Fall LT5 2,400 62.76392 -148.41756 09/07 - 09/08
Fall LT7 3,200 62.86900 -148.70400 09/07 - 09/14
Fall LT8 2,690 62.84956 -149.09381 09/07 - 09/12
Fall LT9 3,280 62.82242 -149.76122 09/07 - 09/14
4.1.4. Data Analysis
4.1.4.1. Spectrogram Preparation
An Excel-based technique was used to visually display 1-second interval Lp data. This approach
is similar to spectrograms of one-third octave band resolution Lp measurement data developed by
NPS. Using conditional formatting, plots of A-weighted one-third octave spectra Lp versus time
were developed (Figure 4-3). Spectrograms enabled analysts to visually distinguish impulsive,
intermittent and short-duration sounds of particular third-octaves (or wider spectra) against a
backdrop of relatively continuous and/or indistinct background sound. The typical conditional
formatting developed for this tool was applied to individual columns of data (Lp at one-third octave
band center frequency resolution) in a three-color scale format of black, blue, and white, and was
adjustable to raise or reduce sharpness and clarity. This approach resulted in improved source
visibility (by raising the contrast against background noise) and enhanced the accuracy of source
identification. In addition to Figure 4-3, below, spectrograms illustrating various other distinct and
recognizable sources (i.e., aircraft, trains, and fauna) are provided in Appendix A.
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 12 September 2015
Figure 4-3. Plot of A-Weighted One-Third Octave Spectra Lp Versus Time: Mechanized Sound (Motorized
Vehicle) and Biophony (Birdsong), Spring Season
4.1.4.2. Audible Sound Analysis
Audible sound was characterized by listening to the audio file segments corresponding to the
graphical anomaly or prominence identified on the spectrogram. Anomalies were recorded and
differentiated by type of audible sound to determine the overall quantity within a specific period
(e.g., 1 hour) at the LT monitoring location. To ensure audible events were adequately quantified
and categorized, analysts performed this kind of “attentive listening” to measured days at the LT
monitors, with the following exceptions:
Partial diurnal cycles (i.e., less than 24 hours) occurring on instrument installation and
recovery days. During such times, investigator and helicopter activity occurred at the
monitoring locations. Further, field investigators were flying by helicopter among the LT
monitoring sites across the Study Area, and thus potentially adding audible helicopter noise
to the measured Lp that would not be considered representative of the non-Project ambient
sound environment.
In some cases, and after a preview of overall or summarized acoustical metrics and
statistics as well as spectrogram-formatted Lp data, some LT measurement days were
considered sufficiently similar to adjoining measured days and thus not subject to detailed
Time
Frequency
Minute Guide
Periodic Bird Chirp
Vehicle Pass By
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 13 September 2015
attentive listening. For example, Lp collected at a location on a Tuesday might appear quite
similar (per this preview) to data from the preceding Monday and proceeding Wednesday.
Collectively, attentive listening over the entire surveyed period amounted to approximately
360 hours or roughly 7 minutes of listening for each 1-hour period of the total 3096 monitored
hours. Spectrogram analysis was completed for approximately 93 percent of the spectrograms—
each analyzed for every hour of each 24-hour measurement period. Natural sound disturbance was
classified as “Very High,” “High,” “Medium,” and “Low” per criteria provided in NPS (2006)
(Table 4-3).
Table 4-3. Natural Sound Disturbance Classification
Classification Standard
Very High
Natural sounds are often interrupted by motorized noise including loud noise. Motorized noise may be
audible up to 50% of any hour, and there may be up to 50 motorized noise intrusions per day that exceed
natural ambient sound. Motorized noise does not exceed 60 A-weighted decibels (dBA).
High
Natural sounds are frequently interrupted by motorized noise, including some loud noise. Motorized noise
may be audible up to 25% of any hour, and there may be as many as 25 motorized noise intrusions per
day that exceed natural ambient sound. Motorized noise does not exceed 60 dBA.
Medium
Natural sounds predominate in this area, but there are infrequent motorized intrusions, a few of which may
be loud. Motorized noise may be audible up to 15% of any hour, and there may be as many as 10
motorized noise intrusions per day that exceed natural ambient sound. Motorized noise does not exceed
40 dBA
Low
Natural sounds predominate in this area and motorized noise intrusions are very rare and usually faint.
Motorized noise may be audible up to 5% of any hour, and there is no more than 1 motorized intrusion
each day that exceeds natural ambient sound. Motorized noise does not exceed 40 dBA.
Source: DNP 2006
Notes: “Audible” means audibility to a person of normal hearing. Maximum sound levels assume the measurement device is more than 50 feet
from the noise source. For comparison, 40 dBA is the overall sound level inside a typical residential home. 70 dBA is the sound level of a
vacuum cleaner as perceived by the user.
4.2. Variances
AEA implemented the methods described in RSP Section 12.6.1 with no variances.
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 14 September 2015
5. RESULTS
Results presented in this section tier off those provided in Section 5.2 of IRS 12.6.
5.1. Review Documentation and Develop Data Needs
The following are laws, ordinances, regulations, standards, and guidance that may influence the
Project construction and operation noise impact assessment:
The second edition of the U.S. Bureau of Reclamation Water and Land Recreation
Opportunity Spectrum Handbook describes guidelines for several social setting attributes
used to characterize or categorize recreation land uses or opportunities. With respect to
sound, a “reasonable standard for the percent of noise disturbances per number of
recreation groups” ranges from 10 percent for an “urban” category to 1 percent for a
“primitive” recreation setting (Bureau of Reclamation 2011).
Table 4-3 reproduces Table 2.5 from the 2006 Denali National Park Backcountry
Management Plan (DNP 2006) and describes four categories of disturbance to what is
otherwise natural soundscape.
There are guidelines at the federal level that direct the consideration of a broad range of
noise and vibration issues as listed below:
o National Environmental Policy Act (42 United States Code [USC] 4321, et seq.)
(Public Law-91-190) (40 Code of Federal Regulations [CFR] § 1506.5)
o Noise Control Act of 1972 (42 USC 4910)
o U.S. Department of Housing and Urban Development Noise Guidelines (24 CFR § 51
subpart B)
o The U.S. Environmental Protection Agency (EPA) has not promulgated standards or
regulations for environmental noise generated by power plants; however, the EPA has
published a guideline that specifically addresses issues of community noise (EPA
1978). This guideline, commonly referred to as the “levels document,” contains goals
for noise levels affecting residential land use of day-night sound level (Ldn) <55 A-
weighted decibel (dBA) for exterior levels and Ldn<45 dBA for interior levels. Chapter
2 of the U.S. Department of Housing and Urban Development Noise Guidebook (24
CFR Section 51.101(a)(8)) also recommends that exterior areas of frequent human use
follow the EPA guideline of 55 dBALdn. However, the same Section 51.101(a)(8)
indicates that a noise level of up to 65 dBALdn could be considered acceptable.
Occupational exposure to noise is regulated by 29 CFR 1910.95, Occupational Noise
Exposure, which in summary describes requirements of an employer for implementation
of feasible administrative or engineering controls, personal protective equipment, and/or a
hearing conservation program to protect its employees against the effects of noise exposure
when it exceeds an average of 90 dBA for an 8-hour period.
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 15 September 2015
As of this writing, no state, borough, or municipality laws, ordinances, or regulations have been
found that specifically apply to noise from hydropower facilities or their construction.
5.2. Seasonal Surveys of Ambient Sound Levels
The following section summarizes results of Lp measurement and DAR data for each LT
monitoring site. Results include percent audibility for categories of natural sounds and
anthropogenic noise, hourly ambient sound levels, and number of “mechanized” sound events per
day. “Mechanized” sound events are also characterized as anthropogenic “disturbances” to the
background typically dominated by naturally occurring sounds.
Table 4-3, in the previous section, lists the criteria used to determine the natural sound disturbance
classifications of low, medium, high, and very high.
For the purposes of this study, “night” is from 2200 hours to 0700 hours, “day” is from 0700 hours.
to 1900 hours p.m., and “evening” is from 1900 hours to 2200 hours.
In the text summaries in this section, the data reported are typically hourly averages over the
monitoring period. For example, to determine the highest percentage of audible mechanized
disturbance for any given hour of the day, data were averaged from the same hour each day (for
example, 6 a.m.) over the whole monitoring period. The highest average percent of that hour where
mechanical noise was audible is discussed. If a different hour (for example, noon) had a larger
maximum on a particular day but the average of that hour over the days of the monitoring period
was lower, only the higher average was considered.
Figures summarizing the collected data for each site follow the report in Appendix C. These figures
are called out as applicable in the text; however, in cases where, for example, no audible
mechanized disturbance events were recorded, the charts depicting disturbance occurrence and
distribution were omitted. The location of each LT monitoring site is shown in Figure 5-1.
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 16 September 2015
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SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
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FERC Project No. 14241 Page 17 September 2015
Figure 5-1. Soundscape Locations - Long Term
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 19 September 2015
5.2.1. Winter Long-Term Acoustic Monitoring
5.2.1.1. Winter LT1
The Winter LT1 soundscape monitor was located 200 feet south of the Denali Highway (Figure 5-
2) and approximately 25 miles west of the Susitna River. This station was within the proposed
Denali Corridor boundary. It was deployed on March 7, 2013, and was operational through March
11, 2013. Table 5-1 provides summary information on Winter LT1.
The most common geophony identified was wind. On average, wind was audible 89 percent of the
time (Figure C-1). The most common biophony identified was birdsong (7 percent) (Figure C-2).
Mechanized sound was audible during 15 events per day (Figures C-6 and 7) lasting 3 percent of
each day. The highest hourly audibility was 11 percent (Figure C-3). Snow machines traversing
the Denali Highway were the primary contributors of mechanized sound, generally peaking in
volume and frequency from 9:00 through 15:00 (Figure C-4). Based on these results, disturbance
to the existing soundscape at Winter LT1 is medium to high.
Based on post-measurement sound source identification and analysis, it is apparent that strong and
continuous wind noise throughout the 24-hour period may significantly reduce audibility and
cataloging of other natural and mechanized noise sources—specifically those that are more distant
and/or have lower sound level magnitudes. For example, DAR and measured noise level data from
March 11, 2013 suggest the Winter LT1 experienced very strong, continuous winds, resulting in
very low detectability of discrete noise-producing events, which may explain the drop in apparent
mechanical events for that 24-hour period.
Over the 4-day period, the average hourly L50 (i.e., median sound level) measurement values
ranged from 30 to 35 dBA at night (Figure C-5), which is consistent with a rural environment.
Hourly L50 increases to a range of 35 to 42 dBA during the daytime. With winds occurring fairly
continuously, the higher daytime range is likely due to birdsong and other fairly continuous sources
of natural sound, such as increased wind speeds.
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 20 September 2015
Figure 5-2. Photo of Long-Term Sound Monitor Winter LT1 Location
Table 5-1. Long-Term Sound Monitor Winter LT1 Summary
Location and purpose Located approximately 200 feet south of Denali Highway at milepost (MP) 115. The purpose of
this station was to collect data along the proposed vehicular access route to the Denali or Denali
East Corridors.
Coordinates Lat: 63.36646, Long: -148.35935 Elevation 2,600 feet
Deployed March 7 – March 12, 2013 Analysis period March 8 – 11, 2013
Disturbance Classification medium - high Access by Snow machine
Temperature (°F) Average: 23.3 Maximum: 26.9 Minimum: 17.6
Average Humidity (%) 70.7 Average Barometric Pressure (Bar) 0.920
Wind Speed (mph) Average: 5 Gust: 26.8
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 21 September 2015
5.2.1.2. Winter LT2
The Winter LT2 soundscape monitor was located approximately 200 feet south of the Denali
Highway (Figure 5-3). This station is approximately 240 feet from Brushkana Creek. It was
deployed on March 7, 2013. Data were collected from March 8 through March 11, 2013. Table 5-
2 provides summary information on Winter LT2.
The most common geophony identified was wind (audible 48 percent of the time) and flowing
water (43 percent) (Figure C-8). The most common biophony identified was birdsong, (4 percent)
(Figure C-9). On average, mechanized sound was audible 5 percent of each day (Figure C-10),
with as much as 19 percent in the highest hour (8 a.m.), and an average of 12 events per day
(Figures C-13 and 14). Due its proximity to the Denali Highway, snow machines traversing the
highway were the primary contributor of mechanized sound, generally peaking in volume from
6:00 through 16:00 (Figure C-11). Based on these results, the existing soundscape disturbance at
Winter LT2 is medium to high.
LT2 is characterized by lower average wind speed and lower wind gust velocity; consequently,
this site has a lower wind noise audibility percentage than Winter LT1. The reduced audibility of
wind is likely a factor in mechanized sound sources being more frequently audible at Winter LT2
than at Winter LT1. Although apparent snow machine traffic was greater at Winter LT1, other
mechanized sounds (including passing aircraft) were more apparent at Winter LT2.
Over the 4-day period, the hourly L50 measurement values ranged from 16 to 23 dBA at night,
which is consistent with a remote rural environment, and rise to a range of 19 to 29 dBA during
the daytime (Figure C-12). The higher daytime range is likely due to birdsong and other fairly
continuous sources of natural sound, such as increased wind speeds and flow rate of running water
(Brushkana Creek).
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 22 September 2015
Figure 5-3. Photo of Long-Term Sound Monitor Winter LT2 Location
Table 5-2. Long-Term Sound Monitor Winter LT2 Summary
Location and purpose Located approximately 7.4 miles east of the intersection of the Denali Corridor and the Denali
Highway. The purpose of this station was to collect data representative of the BLM-managed
Brushkana campground.
Coordinates Lat: 63.28942, Long: -148.06701 Elevation 2,600 feet
Deployed March 7 – March 27, 2013 Analysis period March 8 – 11
Disturbance Classification medium - high Access by Snow machine
Temperature (°F) Average: 20.7 Maximum: 29.8 Minimum: 8.5
Average Humidity (%) 70.7 Average Barometric Pressure (Bar) 0.920
Wind Speed (mph) Average: 5 Gust: 26.8
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 23 September 2015
5.2.1.3. Winter LT4
The Winter LT4 soundscape monitor was located on a remote hillside, approximately 1 mile north
of the Susitna River and 3.5 miles west of the proposed dam site (Figure 5-4). This location was
accessed via helicopter. The monitor was deployed on March 8, 2013, and data were collected on
March 9 through March 10, 2013. Table 5-3 provides summary information on Winter LT4.
The most common geophony identified was flowing water (audible 20 percent of the time) and
wind (59 percent) (Figure C-15). The most common biophony identified was birdsong (3 percent)
(Figure C-16). On average, mechanized sound was audible 17 percent of each day (Figures C-17
and 18), with as much as of 35 percent during the highest hour (due solely to passing aircraft) and
an average of 10 events per day (Figures C-20 and C-21). The number of audible mechanized
events were measured at 16 (March 9, 2013) and 4 (March 10, 2013). Based on these results, the
existing soundscape disturbance at Winter LT4 is high to very high.
The hourly L50 measurement values narrowly ranged between 15 and 18 dBA during both day and
night (Figure C-19). This measurement is consistent with a very remote rural environment under
conditions of low average wind speeds (2 mph) and modest wind gust velocity (10 mph), as was
measured during the survey. This very quiet background helps explain why passing aircraft were
audible and why this location was classified in the high to very high disturbance range, despite
maximum hourly sound levels measuring lower than 30 dBA Leq.
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 24 September 2015
Figure 5-4. Photo of Long-Term Sound Monitor Winter LT4 Location
Table 5-3. Long-Term Sound Monitor Winter LT4 Summary
Location and purpose Located on a hillside approximately 3.4 miles west of the proposed dam site. This site
represented locations near the proposed dam. Monitoring occurred during all four seasons at
this location.
Coordinates Lat: 62.83047, Long: -148.66463 Elevation 2,250 feet
Deployed March 8 – March 27, 2013 Analysis period March 9 – March 10
Disturbance Classification high to very high Access by Helicopter
Temperature (°F) Average: 23 Maximum: 28.9 Minimum: 17
Average Humidity (%) 79.96 Average Barometric Pressure (Bar) 0.931
Wind Speed (mph) Average: 2 Gust: 10.1
5.2.1.4. Winter LT5
The Winter LT5 soundscape monitor was located on a hillside approximately 0.6 miles east of
High Lake (Figure 5-5). It was deployed on March 8, 2013. Data were collected on March 9
through 11 and March 13 and 14, 2013. Table 5-4 provides summary information on Winter LT5.
The most common geophony identified was wind (audible 92 percent of the time) and rain
(3 percent) (Figure C-22). The most common biophony identified was birdsong (3 percent) (Figure
C-23). On average, mechanized sound was audible 2.5 percent of each day (Figures C-24 and 25),
with as much as 5 percent during the highest hour (due solely to passing aircraft). An average of 9
events occurred per day (Figure C-27 and C-28). Based on these results, the existing soundscape
disturbance at Winter LT5 is low to medium.
Over the 5-day period, the hourly L50 measurement values seemed to remain steady at 30 dBA at
night, which is consistent with a rural environment, and rose to a range of 30 to 40 dBA during the
daytime (Figure C-26). The higher daytime range is likely due to birdsong and other fairly
continuous sources of natural sound, such as increased wind speeds. The average hourly Leq values
of between 45 and 65 dBA are indicative of the high average measured wind speed (10 mph) and
very high wind gust velocities (53 mph). These high wind speeds, and the corresponding high
noise levels, would also likely be responsible for the very high wind noise audibility (greater than
90 percent) and thus the very low audibility (5 percent) associated with mechanized sound sources.
In other words, during sustained periods of high winds and wind-caused noise, the likelihood of
such wind noise to mask mechanized sounds in the outdoor ambient environment would be greater.
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 25 September 2015
Figure 5-5. Photo of Long-Term Sound Monitor Winter LT5 Location
Table 5-4. Long-Term Sound Monitor Winter LT5 Summary
Location and purpose On a hillside 0.6 miles east of High Lake. High Lake is equidistant from the Chulitna and Gold
Creek proposed corridors. Monitoring occurred here during winter, spring, and summer.
Coordinates Lat: 62.84934, Long: -149.09233 Elevation 2,680 feet
Deployed March 8 – March 15, 2013 Analysis period March 9 – 11, 13 –14
Disturbance Classification low - medium Access by Helicopter
Temperature (°F) Average: 14.6 Maximum: 20.2 Minimum: 8.3
Average Humidity (%) 61.5 Average Barometric Pressure (Bar) 0.916
Wind Speed (mph) Average: 11.6 Gust: 52.8
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 26 September 2015
5.2.1.5. Winter LT7
The Winter LT7 soundscape monitor was located approximately 9 miles southwest of the Denali
Highway, 25 miles north of the proposed dam site, and approximately 23 miles west of the Susitna
River (Figure 5-6). The instrument was deployed on March 11, 2013. Data were recorded for six
consecutive days between March 12 and March 17, 2013. Table 5-5 provides summary information
on Winter LT7.
The most common geophony identified was wind (audible 83 percent of the time) (Figure C-29).
The most common biophony identified was birdsong (3 percent) (Figure C-30). On average,
mechanized sound was audible 3 percent of each day (Figures C-31 and C-32), with as much as
9 percent during the highest hour (due solely to passing aircraft), and an average of 7 events per
day (Figure C-34 and 35). Based on these results, the existing soundscape at Winter LT7 is low to
medium.
Over the 6-day period, the hourly L50 measurement values narrowly ranged between 15 and
20 dBA (Figure C-33). This is consistent with a very remote rural environment. Given this quiet
background, the variance of average hourly Leq (16 dBA to 41 dBA) indicates the outdoor ambient
noise level is largely driven by wind gusts and/or passing aircraft.
Figure 5-6. Photo of Long-Term Sound Monitor Winter LT7 Location
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 27 September 2015
Table 5-5. Long-Term Sound Monitor Winter LT7 Summary
Location and purpose 1.7 miles west of Brushkana Creek, within proposed Denali Corridor. Low anthropogenic
activity is expected outside of hunting season.
Coordinates Lat: 63.17352, Long: -148.26231 Elevation 3,350 feet
Deployed March 11 – March 27, 2013 Analysis period March 12 – 17
Disturbance Classification low - medium Access by Helicopter
Temperature (°F) Average: 1.7 Maximum: 10.25 Minimum: -7.87
Average Humidity (%) 52.94 Average Barometric Pressure (Bar) 0.894
Wind Speed (mph) Average: 5.1 Gust: 20.1
5.2.2. Spring Long-Term Acoustic Monitoring
5.2.2.1. Spring LT1
The Spring LT1 soundscape monitor was located 4 miles east of the Parks Highway and 2.25 miles
northwest of the Susitna River and the Alaska Railroad (Figure 5-7) for five consecutive days from
May 19 through May 23, 2013. Table 5-6 provides summary information on Spring LT1.
The most common geophony identified was wind (audible 53 percent of the time) (Figure C-36).
The most common biophony identified was birdsong (20 percent) (Figure C-37). On average,
mechanized sound was audible 16 percent of each day (Figures C-38 and 39), with as much as
34 percent during the highest hour (due to passing aircraft and trains), and an average of 34 events
per day (Figure C-41 and 42). Based on these results, the existing soundscape disturbance at Spring
LT1 is high to very high.
The hourly L50 measurement values ranged between 17 and 22 dBA across both day and night
hours (Figure C-40). This measurement is consistent with a very remote rural environment under
conditions of low average wind speeds (2.5 mph) and modest wind gust velocity (8 mph). This
very quiet background explains why passing aircraft and trains were so frequently audible and why
the existing soundscape disturbance was classified as high to very high despite measured
maximum hourly sound levels of less than 50 dBA Leq.
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 28 September 2015
Figure 5-7. Photo of Long-Term Sound Monitor Spring LT1 Location
Table 5-6. Long-Term Sound Monitor Spring LT1 Summary
Location and purpose Near Curry Lookout and Camp Regalvista in Denali State Park. This is a prominent viewpoint
and includes a shelter on the National Register of Historic Places. This location represents a
visitor attraction. Spring and summer monitoring took place here.
Coordinates Lat: 62.62237, Long: -150.09857 Elevation 2,550 feet
Deployed May 18 – May 24, 2013 Analysis period May 19 – 23
Disturbance Classification high – very high Access by Helicopter
Temperature (°F) Average: 32.58 Maximum: 39.3 Minimum: 26.42
Average Humidity (%) 52.16 Average Barometric Pressure (Bar) 0.933
Wind Speed (mph) Average: 2.54 Gust: 7.86
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 29 September 2015
5.2.2.2. Spring LT2
The Spring LT2 soundscape monitor was located on the banks of the Susitna River at the
confluence of the Indian River, approximately 8 miles southeast of the Parks Highway
(Figure 5-8). The instrument was deployed on May 18, 2013. Data were collected for five
consecutive days between May 19 and May 23, 2013. Table 5-7 provides summary information
on Spring LT2.
The most common geophony identified was wind (audible 32 percent of the time) and flowing
water (100 percent) (Figure C-43). The most common biophony identified was birdsong
(32 percent) and insects (2 percent) (Figure C-44). On average, mechanized sound was audible
14 percent of each day (Figures C-45 and 46), with as much as 31 percent during the highest hour
(due to passing aircraft and trains), and an average of 48 events per day (Figures C-48 and 49).
Based on these results, the existing soundscape disturbance at Spring LT2 is high to very high.
Over the 5-day period, the hourly L50 measurement values narrowly ranged between 54 and
56 dBA over both day and night hours (Figure C-47). This indicates the acoustical dominance of
the flowing water of the Susitna River. Low average wind speeds (< 1 mph) and low wind gust
velocity (< 5 mph) as measured during the survey explain audibility of wind-generated noise
during only about a third of the survey period. Despite this steady background noise of flowing
water, passing aircraft and trains on the Alaska Railroad approximately 0.6 miles away were
audible, resulting in the existing soundscape disturbance being rated as high to very high, despite
measured maximum hourly sound levels of less than 60 dBA Leq.
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 30 September 2015
Figure 5-8. Photo of Long-Term Sound Monitor Spring LT2 Location
Table 5-7. Long-Term Sound Monitor Spring LT2 Summary
Location and purpose On the northern shore of the confluence of the Susitna and Indian Rivers. The purpose of this
station was to collect data on the riparian habitat, changes in hydraulic flow during the peak
spring melt-off, and the nearby Alaska railroad.
Coordinates Lat: 62.78604, Long: -149.65572 Elevation 800 feet
Deployed May 18 – May 24, 2013 Analysis period May 19 – 23
Disturbance Classification high – very high Access by Helicopter
Temperature (°F) Average: 38.77 Maximum: 51.62 Minimum: 26.55
Average Humidity (%) 51.73 Average Barometric Pressure (Bar) 0.998
Wind Speed (mph) Average: 0.76 Gust: 4.57
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 31 September 2015
5.2.2.3. Spring LT3
The Spring LT3 soundscape monitor was located approximately 4.5 miles southeast of the Parks
Highway, 3.5 miles northwest of the Susitna River, and 40 miles west of the proposed dam site
(Figure 5-9). It was deployed on May 20, 2013. Data were collected for six consecutive days
between May 21 and May 26, 2013. Table 5-8 provides summary information on Spring LT3.
The most common geophony identified was wind (audible 60 percent of the time) (Figure C-50).
The most common biophony identified was birdsong (58 percent) (Figure C-51). On average,
mechanized sound was audible 24 percent of each day (Figures C-52 and 53), with as much as
46 percent during the highest hour (due to passing aircraft and trains), and an average of 57 events
per day (Figures C-55 and 56). Based on these results, the existing soundscape disturbance at
Spring LT3 is very high.
Over the 6-day period, the hourly L50 measurement values narrowly ranged between 17 and
27 dBA across the day and night hours (Figure C-54). This is consistent with a remote rural
environment. This quiet baseline soundscape explains why passing aircraft and trains on the
Alaska Railroad were frequently audible and why the soundscape was characterized by a very high
disturbance range, despite measured maximum hourly sound levels of less than 50 dBA Leq.
Figure 5-9. Photo of Long-Term Sound Monitor Spring LT3 Location
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
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FERC Project No. 14241 Page 32 September 2015
Table 5-8. Long-Term Sound Monitor Spring LT3 Summary
Location and purpose Located on Kesugi Ridge in Denali State Park. The purpose of this station was to collect data
at this prominent viewpoint and visitor attraction. Long-term data were collected during spring,
summer, and fall.
Coordinates Lat: 62.81964, Long: -149.75472 Elevation 3,230 feet
Deployed May 20 - 27, 2013 Analysis period May 21 – 26
Disturbance Classification very high Access by Helicopter
Temperature (°F) Average: No data Maximum: No data Minimum: No data
Average Humidity (%) No data Average Barometric Pressure (Bar) No data
Wind Speed (mph) Average: No data Gust: No data
5.2.2.4. Spring LT4
The Spring LT4 soundscape monitor was located at the High Lake Lodge and airstrip,
approximately 2 miles north of the Susitna River and 19 miles west of the proposed dam site
(Figure 5-10). The instrument was deployed on May 20, 2013. Data were collected between May
21 and May 27, 2013. Table 5-9 provides summary information on Spring LT4.
The most common geophony identified at the site was wind (audible 23 percent of the time)
(Figure C-57). The most common biophony identified at the site was birdsong (95 percent) (Figure
C-58). On average, mechanized sound was audible 11 percent of each day (Figures C-59 and 60),
with as much as 22 percent during the highest hour (due to passing aircraft), and an average of 26
events per day (Figures C-62 and 63). Based on these results, the existing soundscape disturbance
at Spring LT4 is high.
On May 28, 2013, the property owner visited the site via fixed-wing aircraft and performed noise-
generating tasks, including running a gas generator and operating a bulldozer tractor. Data
collected from this date were not reported due to the atypical ambient noise level at this location.
Over the 7-day period, the hourly L50 measurement values range from 19 to 25 dBA during the
daytime and evening (Figure C-61). Average nighttime L50 values ranged from 17 to 30 dBA,
which may reflect higher wind speeds in the early morning hours during the survey period. These
measurements are consistent with a remote rural environment.
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 33 September 2015
Figure 5-10. Photo of Long-Term Sound Monitor Spring LT4 Location
Table 5-9. Long-Term Sound Monitor Spring LT4 Summary
Location and purpose Southwest of High Lake Lodge, which is equidistant between the Chulitna and Gold Creek
proposed project corridors. Long-term monitoring took place here in winter, spring, and summer.
Coordinates Lat: 62.84393, Long: -149.11560 Elevation 2,400 feet
Deployed May 20 – May 30, 2013 Analysis period May 21 – 27
Disturbance Classification high Access by Helicopter
Temperature (°F) Average: No data Maximum: No data Minimum: No data
Average Humidity (%) No data Average Barometric Pressure (Bar) No data
Wind Speed (mph) Average: No data Gust: No data
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 34 September 2015
5.2.2.5. Spring LT5
The Spring LT5 soundscape monitor was located approximately 1 mile northwest of the Susitna
River, and approximately 3.25 miles west of the proposed dam site (Figure 5-11). The instrument
was deployed May 23, 2013. Data were collected between May 24 and May 28, 2013. Table 5-10
provides summary information on Spring LT5.
The most common geophony identified was flowing water (audible 100 percent of the time) and
wind (35 percent) (Figure C-64). The most common biophony identified was birdsong (98 percent)
(Figure C-65). On average, mechanized sound was audible 8 percent of each day (Figures C-66
and 67), with as much as 36 percent during the highest hour (due to passing aircraft), and up to 17
events per day (Figures C-69 and 70). Based on these results, the existing soundscape disturbance
at Spring LT5 is between high and very high.
Over the 5-day period, the hourly L50 measurement values ranged from 26 to 38 dBA (Figure C-
68). Generally lower values in the daytime suggest these measurements depend on wind speeds (<
1 mph on average, and 6 mph gust), and possibly nearby flowing water from either the Susitna or
a closer tributary.
Figure 5-11. Photo of Long-Term Sound Monitor Spring LT5 Location
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 35 September 2015
Table 5-10. Long-Term Sound Monitor Spring LT5 Summary
Location and purpose Located on a hillside approximately 3.4 miles west of the proposed dam. This site represented
locations near the proposed dam. Monitoring occurred during all four seasons at this location.
Coordinates Lat: 62.83047, Long: -148.66463 Elevation 2,250 feet
Deployed May 23 – May 29, 2013 Analysis period May 24 – 28
Disturbance Classification very high Access by Helicopter
Temperature (°F) Average: 50.97 Maximum: 62.68 Minimum: 38.61
Average Humidity (%) 44.27 Average Barometric Pressure (Bar) 0.933
Wind Speed (mph) Average: 0.79 Gust: 6.09
5.2.2.6. Spring LT6
The Spring LT6 soundscape monitor was located on a hillside approximately 2.5 miles north of
the Susitna River and 1.25 miles northwest of the Watana Creek (Figure 5-12). The instrument
was deployed on May 23, 2013. Data were recorded between May 24 and May 30, 2013. Table 5-
11 provides summary information on Spring LT6.
The most common geophony identified was rain (audible 1 percent of the time) and wind
(57 percent) (Figure C-71). The most common biophony identified was birdsong (91 percent)
(Figure C-72). On average, mechanized sound was audible 2 percent of each day (Figures C-73
and 74), with as much as 11 percent during the highest hour (solely from passing aircraft), and an
average of 11 events per day (Figures C-76 and 77). Based on these results, the existing soundscape
disturbance at Spring LT6 is medium.
Over the 7-day period, the hourly L50 measurement values ranged from 25 to 33 dBA across the
day and night hours (Figure C-75). The generally lower values in the morning hours suggest hourly
L50 measurements are driven by wind patterns.
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 36 September 2015
Figure 5-12. Photo of Long-Term Sound Monitor Spring LT6 Location
Table 5-11. Long-Term Sound Monitor Spring LT6 Summary
Location and purpose Located 2.6 miles NNE of the Confluence of Watana Creek and the Susitna River, to collect
data at this major confluence.
Coordinates Lat: 62.8683, Long: -148.2533 Elevation 2,515 feet
Deployed May 23 – May 31, 2013 Analysis period May 24 – 30
Disturbance Classification medium Access by Helicopter
Temperature (°F) Average: No data Maximum: No data Minimum: No data
Average Humidity (%) No data Average Barometric Pressure (Bar) No data
Wind Speed (mph) Average: No data Gust: No data
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 37 September 2015
5.2.2.7. Spring LT7
The Spring LT7 soundscape monitor was located along the Denali Highway, 0.5 mile south of the
Nenana River, and 10.5 miles east of the Denali and Parks Highway intersection near Cantwell
(Figure 5-13). The instrument was deployed on May 21, 2013. Data were collected from May 22
through May 25, 2013. Table 5-12 provides summary information on Spring LT7.
The most common geophony identified was wind (audible 58 percent of the time) and flowing
water (100 percent) (Figure C-78). The most common biophony identified was birdsong
(99 percent) (C-79). Human speech and activity was audible 25 percent of the time. On average,
mechanized sound was audible 19 percent of each day (Figures C-80 and 81), with as much as
39 percent during the highest hour, and an average of 71 events per day (Figures C-83 and 84).
Anthropogenic sound sources along Denali Highway include generators, music, and automotive
and all-terrain vehicle traffic. Based on these results, existing soundscape disturbance at Spring
LT7 is very high.
Under conditions of low average wind speed (1 mph) and low gust velocity (6 mph), monitoring
position Spring LT7 has correspondingly low wind noise audibility compared to Winter LT1, a
comparable monitoring location along the Denali Highway. In addition, in spite of the nearly
constant audibility of running water, the reduced audibility of wind likely gave mechanized sound
sources (such as passing aircraft and vehicle traffic on the Denali Highway) a greater likelihood
of being audible.
Over the 4-day period, the hourly L50 measurement values ranged from 20 to 29 dBA across the
day and night hours (Figure C-82). This measurement is consistent with a remote rural
environment. The lower end of this range appears to occur during the midday hours and may
suggest a correlation with reduced wind speeds during that time.
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 38 September 2015
Figure 5-13. Photo of Long-Term Sound Monitor Spring LT7 Location
Table 5-12. Long-Term Sound Monitor Spring LT7 Summary
Location and purpose Located adjoining a gravel pullout near milepost 122 of the Denali Highway. The purpose was
to monitor soundscape conditions at the proposed transmission line and vehicular access
route to the Denali Corridor.
Coordinates Lat: 63.39105, Long: -148.56028 Elevation 2,410 feet
Deployed May 21 – May 26, 2013 Analysis period May 22 – 25
Disturbance Classification very high Access by Helicopter
Temperature (°F) Average: 41.9 Maximum: 52.4 Minimum: 28.0
Average Humidity (%) 51.84 Average Barometric Pressure (Bar) 0.932
Wind Speed (mph) Average: 1.12 Gust: 6.15
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 39 September 2015
5.2.2.8. Spring LT9
The Spring LT9 soundscape monitor was located approximately 1.5 miles south of the Susitna
River (Figure 5-14). The instrument was deployed on May 23, 2013. Data were collected from
May 24 through May 30. Table 5-13 provides summary information on Spring LT9.
The most common geophony identified was wind (audible 52 percent of the time) and flowing
water (100 percent) (Figure C-85). The most common biophony identified was birdsong
(76 percent) (Figure C-86). On average, mechanized sound (passing aircraft) was audible 2 percent
of each day (Figures C-87 and 88), with as much as 6 percent during the highest hour, and an
average of 6 events per day (Figures C-90 and 91). Based on these results, existing natural sound
disturbance at Spring LT9 is between low and medium.
Averaged over the 4-day period, the hourly L50 measurement values range from 32 to43 dBA
throughout the diurnal cycle (Figure C-89). This measurement is consistent with a rural
environment. The lower end of this range appears to occur during the daytime hours and suggests
a correlation with reduced wind speeds during that time.
Figure 5-14. Photo of Long-Term Sound Monitor Spring LT9 Location
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 40 September 2015
Table 5-13. Long-Term Sound Monitor Spring LT9 Summary
Location and purpose Located 1.8 miles south of Vee Canyon. The purpose of this station was to collect data at the
easternmost proposed extent of the project reservoir. Long-term monitoring occurred here
during spring, summer, and fall.
Coordinates Lat: 62.67589, Long: -147.527 Elevation 2,800 feet
Deployed May 23 – May 30, 2013 Analysis period May 24 – 30
Disturbance Classification low - medium Access by Helicopter
Temperature (°F) Average: No data Maximum: No data Minimum: No data
Average Humidity (%) No data Average Barometric Pressure (Bar) No data
Wind Speed (mph) Average: No data Gust: No data
5.2.3. Summer Long-Term Acoustic Monitoring
5.2.3.1. Summer LT1
The Summer LT1 soundscape monitor was located approximately 4 miles east of the Parks
Highway, approximately 2.25 miles northwest of the Susitna River and the Alaska Railroad
(Figure 5-15). The instrument was deployed on July 12, 2013. Data were collected July 13 through
15 and July 17 and 18, 2013. Its position was located, and is only 35 feet west of the Spring LT1
monitoring position. Table 5-14 provides summary information on Summer LT1.
The most common geophony identified was wind (audible 88 percent of the time) and rain
(8 percent) (Figure C-92). The most common biophony identified were birdsong (32 percent) and
insects (20 percent) (Figure C-93). On average, mechanized sound was audible 7 percent of each
day (Figures C-94 and 95), with as much as 26 percent during the highest hour (from passing
aircraft and trains), and an average of 27 events per day (Figures C-97 and 98). Based on these
results, existing soundscape disturbance at Summer LT1 is high.
Over the 5-day period, the hourly L50 measurement values ranged between 27 and 38 dBA across
the day and night hours (Figure C-96). This measurement is considerably higher than the Spring
LT1 range of 17-22 dBA. This is likely due to the higher average winds and gusts recorded at the
Summer LT1 position (i.e., 10 mph and 25 mph gust [summer], compared to 2.5 mph and 8 mph
gust [spring]). This variation in wind speed also explains the difference in wind audibility:
88 percent for Summer LT1 versus only 53 percent for Spring LT1. Despite this greater audibility
of natural sounds compared to the Spring LT1 data, passing aircraft and trains were still audible at
a frequency that characterized natural soundscape disturbance as high, despite the maximum
hourly sound levels of less than 55 dBA Leq.
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FERC Project No. 14241 Page 41 September 2015
Figure 5-15. Photo of Long-Term Sound Monitor Summer LT1 Location
Table 5-14. Long-Term Sound Monitor Summer LT1 Summary
Location and purpose Near Curry Lookout and Camp Regalvista in Denali State Park. This is a prominent viewpoint
and includes a shelter on the National Register of Historic Places. This location represents a
visitor attraction. Spring and summer monitoring took place here.
Coordinates Lat: 62.62237, Long: -150.09857 Elevation 2,550 feet
Deployed July 12 – July 20, 2013 Analysis period July 13 – 15, 17 – 18
Disturbance Classification high Access by Helicopter
Temperature (°F) Average: 53.72 Maximum: 67.8 Minimum: 45.6
Average Humidity (%) 81.34 Average Barometric Pressure (Bar) 0.93
Wind Speed (mph) Average: 10.25 Gust: 25.4
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FERC Project No. 14241 Page 42 September 2015
5.2.3.2. Summer LT3
The Summer LT3 soundscape monitor was located approximately 8.5 miles southwest of the
Denali Highway (Figure 5-16). The instrument was deployed on July 12, 2013. Data were recorded
from July 13 through July 18, 2013. Table 5-15 provides summary information on Summer LT3.
The most common biophony identified was birdsong (audible 78 percent of the time) and insects
(22 percent) (Figure C-100). The most common geophony identified was rain (2 percent) and wind
(50 percent) (Figure C-99). On average, mechanized sound was audible 1 percent of each day
(Figures C-101 and 102), with as much as 4 percent during the highest hour (solely from passing
aircraft), and an average of 4 events per day (Figures C-104 and 105). Based on these results, the
existing soundscape disturbance at Summer LT3 is low.
Over the 5-day period, the hourly L50 measurement values narrowly ranged between 27 and
33 dBA across the day and night hours (Figure C-103). This measurement is consistent with a
remote rural environment. Higher values in the nighttime hours indicate higher wind speeds
compared to daytime. This average hourly L50 range is higher than the 15-20 dBA measured at
Winter LT7; however, the average wind speed and gust velocities measured at the two locations
are generally comparable, which suggests that the frequency of audible mechanized noise at both
locations is more contingent on the frequency of passing aircraft than on acoustic masking by the
natural soundscape.
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
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FERC Project No. 14241 Page 43 September 2015
Figure 5-16. Photo of Long-Term Sound Monitor Summer LT3 Location
Table 5-15. Long-Term Sound Monitor Summer LT3 Summary
Location and purpose Located 2.1 miles WNW of Brushkana Creek. The purpose of this station was to collect data
within the middle section of the proposed Denali corridor. This is expected to have low
anthropogenic activity outside of hunting season.
Coordinates Lat: 63.18611, Long: -148.27378 Elevation 3,350 feet
Deployed July 12 – July 20, 2013 Analysis period July 13 – 15, 17 – 18
Disturbance Classification low Access by Helicopter
Temperature (°F) Average: 56.9 Maximum: 71.2 Minimum: 59.3
Average Humidity (%) 66.2 Average Barometric Pressure (Bar) 0.903
Wind Speed (mph) Average: 3.1 Gust: 18.2
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FERC Project No. 14241 Page 44 September 2015
5.2.3.3. Summer LT4
The Summer LT4 soundscape monitor was located approximately 3.3 miles north of the Susitna
River (Figure 5-17). The instrument was deployed on July 12, 2013. Data were collected from July
13 to July 17, 2013. Table 5-16 provides summary information on Summer LT4.
The most common geophony identified was wind (audible 97 percent of the time) (Figure C-106).
The most common biophony identified was birdsong (69 percent) (Figure C-107). On average,
mechanized sound was audible 3 percent of each day (Figures C-108 and 109), with as much as
20 percent during the highest hour (solely from passing aircraft), and an average of 8 events per
day (Figures C-111 and 112). Based on these results, the existing soundscape disturbance at
Summer LT4 is between medium and high.
Over the 4-day period, the hourly L50 measurement values ranged between 26 and 41 dBA (Figure
C-110). This measurement is consistent with a rural environment. Higher values in the daytime
and evening suggest the contribution of higher wind speeds (7 mph average, 24 mph gusts) during
those hours. Although the nearly 100 percent audibility of wind noise provides potential sound-
masking of mechanized sound events, there were daytime hours during which aircraft activity was
frequent and led to the 20 percent audibility in the highest hour. These episodic disturbances were
the primary driver for the classification of natural sound disturbance of medium to high.
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
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FERC Project No. 14241 Page 45 September 2015
Figure 5-17. Photo of Long-Term Sound Monitor Summer LT4 Location
Table 5-16. Long-Term Sound Monitor Summer LT4 Summary
Location and purpose Located on a hillside north of the Susitna and near a group of large, unnamed lakes. The
purpose of this station was to collect data in the northeast portion of the project.
Coordinates Lat: 62.88214, Long: -148.3725 Elevation 2,800 feet
Deployed July 12 – July 20, 2013 Analysis period July 13 – 15, 17
Disturbance Classification medium - high Access by Helicopter
Temperature (°F) Average: 57.4 Maximum: 72.68 Minimum: 47.12
Average Humidity (%) 69.3 Average Barometric Pressure (Bar) 0.922
Wind Speed (mph) Average: 6.6 Gust: 23.9
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
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FERC Project No. 14241 Page 46 September 2015
5.2.3.4. Summer LT5
The Summer LT5 soundscape monitor was located approximately 4.25 miles south of the Susitna
River (Figure 5-18). It was deployed on July 12, 2013. Data were collected from July 13 through
15 and July 17 through 19, 2013. Table 5-17 provides summary information on Summer LT5.
The most common geophony identified was running water (audible 100 percent of the time), wind
(87 percent), and rain (8 percent) (Figure C-113). The most common biophony identified was
birdsong (30 percent) (Figure C-114). The sound of running water was from a flowing creek
located approximately one-tenth of a mile to the north. On average, mechanized sound was audible
4 percent of each day (Figures C-115 and 116), with as much as 15 percent during the highest hour
(solely from passing aircraft), and an average of 12 events per day (Figures C-118 and 119). Based
on these results, existing soundscape disturbance at Summer LT5 is medium.
Over the 5-day period, the hourly L50 measurement values ranged between 27 and 37 dBA (Figure
C-117). Higher average values at night suggest the sound contribution of the higher measured wind
speeds (2 mph average with 17 mph gusts). The consistent water and wind sound may provide
sound masking for mechanized disturbance events. The data suggest that aircraft disturbance is
more frequent during certain daylight hours.
Figure 5-18. Photo of Long-Term Sound Monitor Summer LT5 Location
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FERC Project No. 14241 Page 47 September 2015
Table 5-17. Long-Term Sound Monitor Summer LT5 Summary
Location and purpose Located 0.7 miles southeast of the Fog Lakes group, and south of Fog Creek. The purpose of
this location was to collect data approaching the land ownership boundary.
Coordinates Lat: 62.76392, Long: -148.41756 Elevation 2,400 feet
Deployed July 12 – July 20, 2013 Analysis period July 13 – 15, 17 – 19
Disturbance Classification medium Access by Helicopter
Temperature (°F) Average: 58.3 Maximum: 67.6 Minimum: 48.5
Average Humidity (%) 71.4 Average Barometric Pressure (Bar) 0.932
Wind Speed (mph) Average: 1.9 Gust: 16.6
5.2.3.5. Summer LT6
The Summer LT6 soundscape monitor was located approximately 1 mile northwest of the Susitna
River (Figure 5-19). This location was 40 feet north of Spring LT5 and 0.25 miles east of Winter
LT4. The monitor was deployed on July 12, 2013. Data were collected from July 13 through 15
and July 17, 2013. Table 5-18 provides summary information on Summer LT6.
The most common geophony identified was running water (audible 100 percent of the time) and
wind (78 percent) (Figure C-120). The most common biophony identified was birdsong
(51 percent) (Figure C-121). The sound of running water was from the Susitna River, 1 mile away.
On average, mechanized sound was audible 3 percent of each day (Figures C-122 and 123), with
as much as 17 percent during the highest hour (solely from passing aircraft), and an average of 13
events per day (Figures C-125 and 126). Based on these results, existing soundscape disturbance
at Summer LT6 is between medium and high.
Over the 4-day period, the hourly L50 measurement values ranged between 29 and 34 dBA
throughout the diurnal cycle (Figure C-124). Higher average values at night suggest the sound
contribution of the higher measured wind speeds (3 mph average with 38 mph gusts). The
consistent water and wind sound may provide sound masking for mechanized disturbance events.
The data suggest that aircraft disturbance is more frequent during certain daylight hours.
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 48 September 2015
Figure 5-19. Photo of Long-Term Sound Monitor Summer LT6 Location
Table 5-18. Long-Term Sound Monitor Summer LT6 Summary
Location and purpose Located on a hillside approximately 3.4 miles west of the proposed dam site. This site
represented locations near the proposed dam. Monitoring occurred during all four seasons at
this location.
Coordinates Lat: 62.83047, Long: -148.66463 Elevation 2,250 feet
Deployed July 12 – July 20, 2013 Analysis period July 13 – 15, 17
Disturbance Classification medium - high Access by Helicopter
Temperature (°F) Average: 60 Maximum: 77.7 Minimum: 48.9
Average Humidity (%) 66.45 Average Barometric Pressure (Bar) 0.943
Wind Speed (mph) Average: 3.2 Gust: 37.6
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 49 September 2015
5.2.3.6. Summer LT7
The Summer LT7 soundscape monitor was located on a hillside approximately 3.75 miles north
of the Susitna River (Figure 5-20). The monitor was deployed on July 12, 2013. Data were
collected from July 13 through July 18, 2013. Table 5-19 provides summary information on
Summer LT7.
The most common geophony identified was wind (audible 47 percent of the time) (Figure C-127).
The most common biophony identified was birdsong (32 percent) (Figure C-128). The sound of
running water was from the Susitna River, 1 mile away. On average, mechanized sound was
audible 1 percent of each day (Figures C-129 and 130), with as much as 5 percent during the
highest hour (solely from passing aircraft), and an average of 5 events per day (Figures C-132 and
133). Based on these results, existing soundscape disturbance at Summer LT7 is between low and
medium.
Over the 6-day period, the hourly L50 measurement values ranged between 25 and 35 dBA
throughout the diurnal cycle (Figure C-131). Higher average values in the afternoon and evening
suggest the sound contribution of the higher measured wind speeds (6 mph average with 21 mph
gusts) during those hours. With wind audible only half the time there is greater opportunity for
mechanized disturbance events to be audible. However, the distance of this site from mechanized
activity resulted in a low number of events.
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FERC Project No. 14241 Page 50 September 2015
Figure 5-20. Photo of Long-Term Sound Monitor Summer LT7 Location
Table 5-19. Long-Term Sound Monitor Summer LT7 Summary
Location and purpose Approximately 5.7 miles NW of the proposed dam, along the Chulitna corridor.
Coordinates Lat: 62.869, Long: -148.704 Elevation 3,180 feet
Deployed July 12 – July 20, 2013 Analysis period July 13 – 18
Disturbance Classification low-medium Access by Helicopter
Temperature (°F) Average: 55.7 Maximum: 70.3 Minimum: 44.8
Average Humidity (%) 72.23 Average Barometric Pressure (Bar) 0.911
Wind Speed (mph) Average: 6 Gust: 21
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FERC Project No. 14241 Page 51 September 2015
5.2.3.7. Summer LT8
The Summer LT8 soundscape monitor was located approximately 2 miles north of the Susitna
River (Figure 5-21). This location was 250 feet west of Winter LT5 and 0.8 miles northeast of
Spring LT4. The monitor was deployed on July 12, 2013. Data were collected from July 13 through
15 and July 17 through 19, 2013. Table 5-20 provides summary information on Summer LT8.
The most common geophony identified was wind (audible 72 percent of the time) and rain
(3 percent) (Figure C-134). The most common biophony identified was birdsong (42 percent),
insects (2 percent) and mammals (1 percent) (Figure C-135). The sound of running water was from
the Susitna River, 1 mile away. On average, mechanized sound was audible 13 percent of each day
(Figures C-136 and 137), with as much as 34 percent during the highest hour (solely from passing
aircraft), and an average of 44 events per day (Figures C-139 and 140). Based on these results,
existing soundscape disturbance at Summer LT8 is between high and very high.
Over the 6-day period, the hourly L50 measurement values ranged between 20 and 35 dBA
throughout the diurnal cycle (Figure C-138). Higher average values during the day suggest the
sound contribution of the higher measured wind speeds (6 mph average with 21 mph gusts) during
those hours. When compared to the winter LT5 data from close to the same location, the far greater
number of aircraft events during the summer contributed to the seasonal change from a low-to-
medium rating to a high-to-very high rating for existing soundscape disturbance.
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FERC Project No. 14241 Page 52 September 2015
Figure 5-21. Photo of Long-Term Sound Monitor Summer LT8 Location
Table 5-20. Long-Term Sound Monitor Summer LT8 Summary
Location and purpose Located on a hillside 0.6 miles east of High Lake. The purpose of this station was to establish
baseline monitoring between the proposed Chulitna and Gold Creek corridors.
Coordinates Lat: 62.84956, Long: -149.09381 Elevation 2,680 feet
Deployed July 12 – July 20, 2013 Analysis period July 13 – 15, 17 – 19
Disturbance Classification high – very high Access by Helicopter
Temperature (°F) Average: 55.5 Maximum: 71.6 Minimum: 46.0
Average Humidity (%) 77.26 Average Barometric Pressure (Bar) 0.920
Wind Speed (mph) Average: 6.2 Gust: 21.5
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FERC Project No. 14241 Page 53 September 2015
5.2.3.8. Summer LT9
The Summer LT9 soundscape monitor was located approximately 3.75 miles northwest of the
Susitna River (Figure 5-22). This location was 0.25 miles northwest of Spring LT3. The monitor
was deployed on July 12, 2013. Data were collected from July 13 through July 13 through 15 and
July 17, 2013. Table 5-21 provides summary information on Summer LT9.
The most common geophony identified was wind (audible 86 percent of the time) and rain
(5 percent) (Figure C-141). The most common biophony identified was birdsong (31 percent) and
insects (5 percent) (Figure C-142). On average, mechanized sound was audible 5 percent of each
day (Figures C-143 and 144), with as much as 12 percent during the highest hour (from passing
aircraft and trains), and an average of 19 events per day (Figures C-146 and 47). Based on these
results, existing soundscape disturbance at Summer LT9 is between medium and high.
Over the 4-day period, the hourly L50 measurement values ranged between 20 and 40 dBA across
the day and night hours (Figure C-145). Higher average values at night suggest the sound
contribution of the higher measured wind speeds (9 mph average with 32 mph gusts) during those
hours.
Figure 5-22. Photo of Long-Term Sound Monitor Summer LT9 Location
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FERC Project No. 14241 Page 54 September 2015
Table 5-21. Long-Term Sound Monitor Summer LT9 Summary
Location and purpose Located on Kesugi Ridge in Denali State Park. The purpose of this station is to collect data at
this prominent viewpoint and visitor attraction.
Coordinates Lat: 62.82242, Long: -149.76122 Elevation 3,300 feet
Deployed July 12 – July 20, 2013 Analysis period July 13 – 15, 17
Disturbance Classification medium - high Access by Helicopter
Temperature (°F) Average: 52.8 Maximum: 66 Minimum: 45.6
Average Humidity (%) 48.12 Average Barometric Pressure (Bar) 0.908
Wind Speed (mph) Average: 9.1 Gust: 32.5
5.2.4. Fall Season Long-Term Acoustic Monitoring
5.2.4.1. Fall LT1
The Fall LT1 soundscape monitor was located 3.75 miles northwest of the Susitna River and 4.25
miles south of the Parks Highway (Figure 5-23). The monitor was deployed on September 7, 2013.
Data were collected on September 8, 2013. Table 5-22 provides summary information on Fall LT1.
The most common geophony identified was wind (audible 92 percent of the time) and rain
(40 percent) (Figure C-148). The most common biophony identified was birdsong (4 percent)
(Figure C-149). Mechanized sound was audible 3 percent of the day, and 43 percent during the
highest hour (from passing aircraft and trains) (Figure C-150). Six disturbance events occurred
(Figure C-151). Based on these results, existing soundscape disturbance at Fall LT1 is between
high and very high.
Hourly L50 measurement values ranged between 22 and 59 dBA (Figure C-152). Higher values at
night suggest the sound contribution of the higher measured wind speeds (3 mph average with
38 mph gusts). The consistent water and wind sound may provide sound masking for mechanized
disturbance events. The data suggest that aircraft disturbance is more frequent during certain
daylight hours. Despite the low overall percentage of time that mechanized noise is audible, its
concentration within a brief time period resulted in this site exceeding the criteria for high
disturbance on September 8.
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FERC Project No. 14241 Page 55 September 2015
Figure 5-23. Photo of Long-Term Sound Monitor Fall LT1 Location
Table 5-22. Long-Term Sound Monitor Fall LT1 Summary
Location and purpose Located on Kesugi Ridge in Denali State Park.
Coordinates Lat: 62.822417, Long: -149.761222 Elevation 3,240 feet
Deployed September 7 – September 16, 2013 Analysis period September 8
Disturbance Classification high – very high Access by Helicopter
Temperature (°F) Average: 43.64 Maximum: 46.7 Minimum: 40.6
Average Humidity (%) 81.3 Average Barometric Pressure (Bar) 0.880
Wind Speed (mph) Average: 14.8 Gust: 33.5
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FERC Project No. 14241 Page 56 September 2015
5.2.4.2. Fall LT2
The Fall LT2 soundscape monitor was located 3.75 miles north of the Susitna River, in the same
location as Summer LT7 (Figure 5-24). The monitor was deployed on September 7, 2013. Data
were collected on September 8, 2013. Table 5-23 provides summary information on Fall LT2.
The most common geophony identified was wind (audible 100 percent of the time) and rain
(76 percent) (Figure C-153). The most common biophony identified was birdsong (3 percent)
(Figure C-154). No mechanized sound was audible. Based on these results, existing soundscape
disturbance at Fall LT2 is none to low.
Hourly L50 measurement values ranged between 29 and 40 dBA (Figure C-155). Higher values
during the day and evening suggest the sound contribution of the higher measured wind speeds (5
mph average with 23 mph gusts) during those times. The constant wind may provide sound
masking for mechanized disturbance events. As was noted for Summer LT7, the remoteness of
this location from mechanized activity also contributed to the lack of soundscape disturbance
events.
Figure 5-24. Photo of Long-Term Sound Monitor Fall LT2 Location
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FERC Project No. 14241 Page 57 September 2015
Table 5-23. Long-Term Sound Monitor Fall LT2 Summary
Location and purpose Located along the Chulitna corridor, approximately 5.7 miles NW of the proposed Dame site.
Coordinates Lat: 62.869, Long: -148.704 Elevation 3,180 feet
Deployed September 7 – September 16, 2013 Analysis period September 8
Disturbance Classification none to low Access by Helicopter
Temperature (°F) Average: 44.4 Maximum: 48.2 Minimum: 413
Average Humidity (%) 85.37 Average Barometric Pressure (Bar) 0.890
Wind Speed (mph) Average: 5.4 Gust: 23
5.2.4.3. Fall LT3
The Fall LT3 soundscape monitor was located 3.3 miles north of the Susitna River, in the same
location as Summer LT4 (Figure 5-25). The monitor was deployed on September 7, 2013. Data
were collected on September 8, 2013. Table 5-24 provides summary information on Fall LT3.
The most common geophony identified was wind (audible 100 percent of the time) and rain
(39 percent) (Figure C-156). The most common biophony identified was birdsong (7 percent)
(Figure C-157). No mechanized sound was audible. Based on these results, existing soundscape
disturbance at Fall LT3 is none to low.
Hourly L50 measurement values ranged between 22 and 44 dBA (Figure C-158). This reflects
varying contributions of noise from rain and wind (5 mph average with 23 mph gusts) during those
times. The constant wind may provide sound masking for mechanized disturbance events. The
lack of passing aircraft that day contributed to the lack of soundscape disturbance, as compared to
the summer LT4 data.
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FERC Project No. 14241 Page 58 September 2015
Figure 5-25. Photo of Long-Term Sound Monitor Fall LT3 Location
Table 5-24. Long-Term Sound Monitor Fall LT3 Summary
Location and purpose Located on a hillside north of the Susitna River, near a group of large, unnamed lakes.
Coordinates Lat: 62.882139, Long: -148.3725 Elevation 2,820 feet
Deployed September 7 – September 16, 2013 Analysis period September 8
Disturbance Classification none - low Access by Helicopter
Temperature (°F) Average: 50.75 Maximum: 64.2 Minimum: 48.0
Average Humidity (%) 66.05 Average Barometric Pressure (Bar) 0.900
Wind Speed (mph) Average: 3.6 Gust: 16.8
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FERC Project No. 14241 Page 59 September 2015
5.2.4.4. Fall LT4
The Fall LT4 soundscape monitor was located 1 mile north of the Susitna River (Figure 5-26). The
monitor was deployed on September 7, 2013. Data were collected on September 8, 2013. Table 5-
25 provides summary information on Fall LT4.
The most common geophony identified was wind (audible 100 percent of the time) and rain
(59 percent) (Figure C-159). The most common biophony identified was birdsong (9 percent)
(Figure C-160). Mechanized sound was audible 2 percent of the day (Figures C-161 and 162) and
10 percent during the highest hour (solely from passing aircraft). Seven disturbance events
occurred. Based on these results, existing soundscape disturbance at Fall LT4 is between low and
medium.
Hourly L50 measurement values ranged between 17 and 32 dBA (Figure C-163). The dBA levels
were low overall during this monitoring event, which can contribute to the audibility of
mechanized activity.
Figure 5-26. Photo of Long-Term Sound Monitor Fall LT4 Location
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Table 5-25. Long-Term Sound Monitor Fall LT4 Summary
Location and purpose Located on a hilltop approximately one mile WNW of Vee Canyon.
Coordinates Lat: 62.711356, Long: -147.579455 Elevation 3,090 feet
Deployed September 7 – September 16, 2013 Analysis period September 8
Disturbance Classification medium Access by Helicopter
Temperature (°F) Average: 49.2 Maximum: 55.0 Minimum: 32.0
Average Humidity (%) 71.64 Average Barometric Pressure (Bar) 0.890
Wind Speed (mph) Average: 5.4 Gust: 22.5
5.2.4.5. Fall LT5
The Fall LT5 soundscape monitor was located 4.25 miles south of the Susitna River, in the same
location as Summer LT5 (Figure 5-27). The monitor was deployed on September 7, 2013. Data
were collected on September 8, 2013. Table 5-26 provides summary information on Fall LT5.
The most common geophony identified was flowing water (audible 100 percent of the time), wind
(67 percent), and rain (21 percent) (Figure C-164). The most common biophony identified was
birdsong (8 percent) (Figure C-165). The sound of flowing water was from a creek approximately
one tenth of a mile to the north. Mechanized sound was audible 1 percent of the day (Figure C-
166) and 20 percent during the highest hour (solely from passing aircraft). Four disturbance events
occurred (Figure C-167. Based on these results, existing soundscape disturbance at Fall LT5 is
between medium and high.
Hourly L50 measurement values ranged between 38 and 42 dBA (Figure C-168). Higher levels at
night suggest the contribution of higher measured wind speeds (5 mph average, 23 mph gusts)
during those hours. The constant sound of flowing water and wind may provide sound masking of
mechanized disturbance events and was louder due to seasonal weather than the data collected
from Summer LT5. Although mechanized sound was only audible for 1 percent of the day, its
concentration in a single hour (20 percent) exceeds the medium rating for soundscape disturbance.
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
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FERC Project No. 14241 Page 61 September 2015
Figure 5-27. Photo of Long-Term Sound Monitor Fall LT5 Location
Table 5-26. Long-Term Sound Monitor Fall LT5 Summary
Location and purpose Located 0.7 miles southeast of the Fog Lakes, and south of Fog Creek.
Coordinates Lat: 62.763917, Long: -148.417556 Elevation 2,400 feet
Deployed September 7 – September 16, 2013 Analysis period September 8
Disturbance Classification medium - high Access by Helicopter
Temperature (°F) Average: 46.9 Maximum: 53.06 Minimum: 42.26
Average Humidity (%) 83.18 Average Barometric Pressure (Bar) 0.920
Wind Speed (mph) Average: 5.3 Gust: 22.8
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
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5.2.4.6. Fall LT7
The Fall LT7 soundscape monitor was located approximately 0.75 mile northwest of the Susitna
River (Figure 5-28). The monitor was deployed on September 7, 2013. Data were collected from
September 8 through September 13, 2013. Table 5-27 provides summary information on Fall LT7.
The most common geophony identified was flowing water (audible 100 percent of the time), wind
(53 percent), and rain (37 percent) (Figure C-169). The most common biophony identified was
birdsong (8 percent) (Figure C-170). The sound of flowing water came from the Susitna River. On
average, mechanized sound was audible 7 percent of each day (Figures C-171 and 172), with as
much as 15 percent during the highest hour (from passing aircraft), and an average of 20 events
per day (Figures C-174 and 175). Based on these results, existing soundscape disturbance at Fall
LT7 is between medium and high.
Over the 4-day period, the hourly L50 measurement values ranged between 25 and 32 dBA
throughout the diurnal cycle (Figure C-173).The constant sound of water and frequent wind may
sound-mask mechanized disturbance events. Data suggest that aircraft activity is concentrated
during certain hours of the day.
Figure 5-28. Photo of Long-Term Sound Monitor Fall LT7 Location
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Table 5-27. Long-Term Sound Monitor Fall LT7 Summary
Location and purpose Located in a bog in a U-bend of the Susitna River. The purpose of this station was to collect
data near the land ownership boundary.
Coordinates Lat: 62.7805, Long: -148.7414 Elevation 2,040 feet
Deployed September 7 – September 16, 2013 Analysis period September 8 – 13
Disturbance Classification medium - high Access by
Temperature (°F) Average: 45.3 Maximum: 55.9 Minimum: 39.5
Average Humidity (%) 83.21 Average Barometric Pressure (Bar) 0.935
Wind Speed (mph) Average: 2.19 Gust: 25.2
5.2.4.7. Fall LT8
The Fall LT8 soundscape monitor was located approximately 8.75 miles north of the Susitna River
(Figure 5-29). The monitor was deployed on September 7, 2013. Data were collected on September
8, 9, and 11, 2013. Table 5-28 provides summary information on Fall LT8.
The most common geophony identified was flowing water (audible 100 percent of the time), rain
(48 percent), and wind (30 percent) (Figure C-176). The most common biophony identified was
birdsong (31 percent) (Figure C-177). The sound of flowing water came from nearby creeks, the
closest being less than 0.25 mile west. On average, mechanized sound was audible 4 percent of
each day (Figures C-178 and 179), with as much as 12 percent during the highest hour (from
passing aircraft), and an average of 15 events per day (Figures C-181 and 182). Based on these
results, existing soundscape disturbance at Fall LT8 is between medium and high.
Over the 4-day period, the hourly L50 measurement values ranged between 25 and 32 dBA (Figure
C-180).The constant sound of water and frequent wind may sound-mask mechanized disturbance
events. Data suggest that aircraft activity is concentrated during certain hours of the day.
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Figure 5-29. Photo of Long-Term Sound Monitor Fall LT8 Location
Table 5-28. Long-Term Sound Monitor Fall LT8 Summary
Location and purpose Located 1.5 miles north of the confluence of Portage Creek and Thoroughfare Creek, on a
hillside between the creeks. The purpose of this station was to collect data representative of
the north section of the project area.
Coordinates Lat: 62.94146, Long: -149169973 Elevation 2,200 feet
Deployed September 7 – September 16, 2013 Analysis period September 8 – 9, 11
Disturbance Classification medium - high Access by Helicopter
Temperature (°F) Average: No data Maximum: No data Minimum: No data
Average Humidity (%) No data Average Barometric Pressure (Bar) No data
Wind Speed (mph) Average: No data Gust: No data
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5.2.4.8. Fall LT9
The Fall LT9 soundscape monitor was located approximately 0.25 mile south of the Denali
Highway (Figure 5-30). The monitor was deployed on September 7, 2013. Data were collected on
September 8, 9, 11, and 12, 2013. Table 5-29 provides summary information on Fall LT9.
The most common geophony was wind (audible 39 percent of the time) and rain (35 percent)
(Figure C-183). The most common biophony was birdsong (4 percent) (Figure C-184). On
average, mechanized sound was audible 24 percent of each day (Figures C-185 and 186), with as
much as 41 percent during the highest hour, and an average of 109 events per day (Figures C-188
and 189). Disturbance was from a variety of sources such as generators, music, aircraft, and
automotive and ATV traffic on the highway. Based on these results, the existing soundscape
disturbance at Fall LT9 is very high.
Over the 4 days, the hourly L50 measurement values ranged between 27 and 32 dBA (Figure C-
187).The relatively intermittent wind and low wind speeds (less than 2 mph average with gusts up
to 19 mph) provided little opportunity for sound masking. This and proximity to the highway
contributed to the high level of disturbance.
Figure 5-30. Photo of Long-Term Sound Monitor Fall LT9 Location
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Table 5-29. Long-Term Sound Monitor Fall LT9 Summary
Location and purpose Located where the proposed Denali corridor intersects the Denali Highway, near milepost
113.
Coordinates Lat: 63.345244, Long: -148.301793 Elevation 2,740 feet
Deployed September 7 – September 16, 2013 Analysis period September 8, 9, 11 – 12
Disturbance Classification very high Access by Helicopter
Temperature (°F) Average: 44.2 Maximum: 54.8 Minimum: 36.6
Average Humidity (%) 83.65 Average Barometric Pressure (Bar) 0.910
Wind Speed (mph) Average: 1.4 Gust: 17.9
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6. DISCUSSION
6.1. Review Documentation
Per Section 12.6.4 of the RSP, the study team reviewed laws, ordinances, regulations, standards,
and guidance that may influence the Project construction and operation noise impact assessment.
These efforts fulfill the objectives specified in the RSP Section 12.6.2. The data presented in
Section 5.1 will be used for further analyses of soundscape impacts from the Project.
6.2. Seasonal Surveys of Ambient Sound Levels
As specified in Section 12.6.4 of the RSP, the study team conducted observations of perceived and
identifiable sources of sound contributing to the ambient sound environment and the conditions
during which they occur. This survey was conducted four times, associated with each of the four
distinct seasons (i.e., summer, fall, winter, spring).
At a total of 23 LT locations, SPL metrics, statistical data, and DAR data from the four seasonal
soundscape field surveys were successfully collected for multiple consecutive 24-hour periods. Of
these, at least seven LT positions could reasonably be considered “co-located” and thus represent
SPL and DAR data collection for more than one seasonal survey, which provides the kind of data
that enables both a comparison of seasonal soundscapes (and the underlying acoustical
contributors) and the comparison of predicted Project operation and construction noise with a
seasonally appropriate baseline setting. For example, if a particular noise-producing construction
activity was expected to take place during the summer season, then available baseline soundscape
data from the summer survey would likely be used for any relative (e.g., increase over existing
ambient) noise impact assessment.
Section 5.2 outlines the results of the detailed analysis of the baseline data from the seasonal survey
conducted and the following detailed findings and information were presented:
Reasonable identification of apparent significant acoustical contributors during a
measurement period, including Project study activities and non-Project transportation and
recreation activities that can be distinguished from the apparent “natural” background or
specific naturally occurring sound events or conditions.
Reasonable identification of apparent significant acoustical contributors attributed to
naturally occurring sound events or conditions (e.g., birds or insects).
Where and when data is available, correlation of wind speed with measured SPL and AR.
One-third or octave-band analysis of measured sound, plotted versus time.
Statistical values to help characterize the frequency of apparent anthropogenic sounds as a
portion of entire measurement duration.
The overall soundscape of the Study Area is dominated by natural sounds such as winds traversing
the rocky and/or vegetated landscape, rain and other meteorological phenomena, running water,
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and by birds, insects, and other fauna. However, within the Study Area the soundscape at the local
scale depends on the individual site’s proximity to the near and distant acoustical contributors that
make up the outdoor ambient sound environment, which includes natural sounds that can range
from very quiet to very loud. In other words, a naturally dominated soundscape should not be
interpreted as being synonymous with very low measured sound levels.
The Study Area contains soundscapes having a wide range of existing natural sound disturbance.
Very remote locations such as Brushkana (Winter LT7 and Summer LT3) and Vee Canyon (Spring
LT9 and Fall LT4) had on average fewer than 10 natural sound disturbances per day and such
disturbances (due largely to passing aircraft) were audible for no more than 6 minutes out of a
given hour. On the other end of the spectrum, locations along the Denali Highway (e.g., Fall LT9)
experience a much greater frequency of natural sound disturbance. While these observations may
seem obvious for monitoring locations like Fall LT9 and Winter LT1 that adjoin or are close to
this known seasonal travel route, it is less obvious for soundscapes like Kesugi Ridge (e.g., Spring
LT3, Fall LT1). These sites seem remote based on access difficulty, but are in fact exposed to very
high counts of natural sound disturbance. Both the potential of a very low natural sound level (calm
winds) and the proximity of surface (highway and railroad) and aviation transportation routes
contribute to the audibility of mechanized sound events.
The study team found that some soundscapes in the Study Area exhibit characteristics of an
environment where a visitor would experience little or no evidence of human settlement, influence,
or contact. However, many soundscapes within the Study Area currently have some degree of
existing natural sound disturbance. Although the seasons certainly impart changes on the surveyed
environment, in some instances, disturbance sources were found to change with the seasons. For
instance, road vehicles using the unpaved Denali Highway in the summer and fall are replaced by
snow machines using the same route in the winter and early spring.
Common to all seasons and at virtually all surveyed locations is the influence of passing aircraft
as both a source of natural sound disturbance and a nearly ubiquitous component of the existing
soundscape in the Study Area.
The data presented in Section 5.2 support the following findings and observations:
The narrow difference (i.e., less than 2 dBA) among overall average Leq, L10 (sound level
exceeded 10 percent of the time), L50, and L90 at Spring LT2 is consistent with the proximity
of the monitor to a continuous source of sound emission: flowing water of Indian River.
Background sound (L90) tends to be 5-6 dBA less than L50 (median sound level) during
spring. Aside from LT2, it ranged between 16 and 30 dBA. Median sound levels ranged
(again, with the exception of LT2) between 20 and 35 dBA. These dBA ranges are
generally compatible with an EPA expectation of 35 dBA day-night sound level (Ldn) for
“wilderness ambient” (EPA 1978). Aircraft overflights, which can be significantly louder
than the background sound level, help caused the overall average Leq for some monitoring
locations, such as LT1, to be considerably higher than the L50 or even the L10 measurement
results.
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6.3. Variances
AEA provided results as described in RSP Section 12.6.1 with no variances.
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7. REFERENCES
AEA (Alaska Energy Authority). 2011. Pre-application Document: Susitna-Watana Hydroelectric
Project FERC Project No. 14241. Prepared for the Federal Energy Regulatory
Commission, Washington, DC.
———2012. Revised Study Plan: Susitna-Watana Hydroelectric Project FERC Project No.
14241. December 2012. Prepared for the Federal Energy Regulatory Commission by the
Alaska Energy Authority, Anchorage, Alaska. http://www.susitna-
watanahydro.org/study-plan.
Bureau of Reclamation. 2011. Water and Land Recreation Opportunity Spectrum (WALROS).
http://www.usbr.gov/recreation/publications/WALROS_Handbook_2011.pdf. Accessed
October 26, 2015.
EPA (U.S. Environmental Protection Agency). 1978. Protective Noise Levels. (USEPA 550/9-
79-100). http://nepis.epa.gov. Accessed December 16, 2013.
NPS (National Park Service). 2006. Denali National Park and Preserve Final Backcountry
Management Plan. U.S. Department of the Interior.
———. 2008. Acoustic Sampling and Analysis Guide. Version 1.3. U.S. Department of Interior.
———. 2009. Denali National Park and Preserve Acoustic monitoring report. Published Report-
2175687. J. Withers. U.S. Department of Interior.
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APPENDIX A: GLOSSARY OF TERMS
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The following terms, metrics, statistical values and concepts are used in the presentation of field
survey data and observations in this study report.
Noise Whether something is perceived as a noise event is influenced by the type
of sound, the perceived importance of the sound and its appropriateness in
the setting, the time of day, the type of activity during which the noise
occurs, and the sensitivity of the listener.
Sound For purposes of this document, sound is a physical phenomenon generated
by minute vibrations that result in waves that travel through a medium,
such as air, and result in auditory perception by the human brain. Sound
may, in most cases, be used interchangeably with “noise” when the latter is
not used specifically to denote unwanted sound.
Frequency (Hz) Sound frequency is measured in Hertz (Hz), which is a measure of how
many times each second the crest of a sound pressure wave passes a fixed
point. For example, when a drummer beats a drum, the skin of the drum
vibrates a number of times per second. When the drum skin vibrates 100
times per second it generates a sound pressure wave that is oscillating at
100 Hz, and this pressure oscillation is perceived by the ear/brain as a tonal
pitch of 100 Hz. Sound frequencies between 20 and 20,000 Hz are within
the range of sensitivity of the best human ear.
Amplitude or
Level (dB)
Sound level or amplitude is measured in decibels (dB) using a logarithmic
scale. A sound level of zero dB is approximately the threshold of human
hearing and is barely audible under extremely quiet listening conditions.
Normal speech has a sound level of approximately 60 dB. Sound levels
above approximately 110 dB begin to be felt inside the human ear as
discomfort and eventually pain at 120 dB and higher levels. The minimum
change in the sound level of individual events that an average human ear
can detect is about 1 to 2 dB. A 3 to 5 dB change is readily perceived. A
change in sound level of about 10 dB is usually perceived by the average
person as a doubling (or if decreasing by 10 dB, halving) of the sound’s
loudness.
Sound Pressure
Level (Lp or
SPL)
Sound level is usually expressed by reference to a known standard. This
document refers to sound pressure level (SPL or Lp). In expressing sound
pressure on a logarithmic scale, the sound pressure is compared to a
reference value of 20 micropascals (µPa). Lp depends not only on the
power of the source, but also on the distance from the source and on the
acoustical characteristics of the space surrounding the source.
A-weighting Sound from a tuning fork contains a single frequency (a pure tone), but
most sounds one hears in the environment do not consist of a single
frequency and instead are composed of a broad band of frequencies
differing in sound level. The method commonly used to quantify
environmental sounds consists of evaluating all frequencies of a sound
according to a weighting system that reflects the typical frequency-
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dependent sensitivity of average healthy human hearing. This is called “A-
weighting,” and the decibel level measured is referred to as dBA. In
practice, the level of a noise source is conveniently measured using a
sound level meter that includes a filter corresponding to the dBA “curve”
of decibel adjustment per octave band center frequency from a “flat” or
unweighted SPL.
Equivalent
Sound Level
(Leq)
Leq is the energy mean, A-weighted sound or noise level during a period of
time. It is the “equivalent” continuous decibel level that would have to be
produced by a given source to equal the fluctuating decibel level over the
same period of time that is either measured or modeled.
Median Sound
Level (L50)
What the National Park Service often calls an “existing ambient sound,”
this statistical value is the A-weighted dB level exceeded 50 percent of the
time for a given short-term measurement or long-term monitoring period.
In other words, the indicated dBA is the median Lp measured for that
period. Like the equivalent sound level (Leq), the dBA represented by this
value includes contribution from all natural sounds and all mechanical,
electrical, and other human-caused sounds in an area.
Percentile
Sound Level
(Lx)
The x-percentile-exceeded sound level is the sound level that is exceeded
x percent of the measurement period. For example, the hourly L10 is the
sound level that is exceeded 10 percent of a measurement hour. The hourly
L50 is the sound level that is exceeded 50 percent of the measurement hour.
The L50 is also known as the median sound level. Similarly, the hourly L90
is the sound level that is exceeded 90 percent of a given measurement hour.
Time Audible
(%TA)
The cumulative (not necessarily continuous) percentage of time within a
defined time period that a particular and identifiable sound source (or if not
specific, considered to belong to some defined category) is audible to a
listener of average healthy human hearing.
Maximum
Sound Level
(Lmax)
The maximum or largest-value sound level (in A-weighted decibels)
measured during a given monitoring period at a measurement location.
Minimum
Sound Level
(Lmin)
The minimum or lowest-value sound level (in A-weighted decibels)
measured during a given monitoring period at a measurement location.
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APPENDIX B: SPECTROGRAPHS
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Helicopter Flyover
Sample from Summer
LT1
7/13/13 – 08:00
Fixed Wing Propeller
Flyover
Sample from Summer
LT4
7/13/13 – 09:00
Birdcall
Sample from Spring
LT4
5/27/13 – 06:00
ATV Pass-By
Sample from Fall LT9
9/9/13 – 09:00
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Jet Aircraft Pass-By
Sample from Fall LT9
9/9/13 – 10:00
Proximal Flying Insect
Sample from Summer
LT1
7/13/13 – 09:00
Locomotive Noise
with Whistle at 49
Minute Mark
Sample from Spring
LT3
5/22/13 – 02:00
Precipitation Onset
Sample from Fall LT9
9/11/13 – 04:00
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Running Water
Sample from Fall LT5
9/8/13 – 07:00
Source Masking
Caused by Wind
(25MPH Gusts)
Sample from Winter
LT5
7/13/13 – 19:00
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APPENDIX C: GRAPHS OF LONG-TERM MONITORING DATA
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Figure C-1. Geophony at Monitor Winter LT1
Figure C-2. Biophony at Monitor Winter LT1
Figure C-3. Mechanized sound at Winter LT1: Average hourly %
Figure C-4. Mechanized sound at Winter LT1: Daily hourly %
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Figure C-5. Sound Pressure Levels at Winter LT1
Figure C-6. Audible mechanized events per day at Winter LT1
Figure C-7. Audible mechanized events distribution by hour at Winter LT1
Figure C-8. Geophony at Monitor Winter LT2
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Figure C-9. Biophony at Monitor Winter LT2
Figure C-10. Mechanized sound at Winter LT2: Average hourly %
Figure C-11. Mechanized sound at Winter LT2: Daily hourly %
Figure C-12. Sound Pressure Levels at Winter LT2
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Figure C-13. Audible mechanized events per day at Winter LT2
Figure C-14. Audible mechanized events distribution by hour at Winter LT2
Figure C-15. Geophony at Monitor Winter LT4
Figure C-16. Biophony at Monitor Winter LT4
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Figure C-17. Mechanized sound at Winter LT4: Average hourly %
Figure C-18. Mechanized sound at Winter LT4: Daily hourly %
Figure C-19. Sound Pressure Levels at Winter LT4
Figure C-20. Audible mechanized events per day at Winter LT4
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Figure C-21. Audible mechanized events distribution by hour at Winter LT4
Figure C-22. Geophony at Monitor Winter LT5
Figure C-23. Biophony at Monitor Winter LT5
Figure C-24. Mechanized sound at Winter LT5: Average hourly %
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Figure C-25. Mechanized sound at Winter LT5: Daily hourly %
Figure C-26. Sound Pressure Levels at Winter LT5
Figure C-27. Audible mechanized events per day at Winter LT5
Figure C-28. Audible mechanized events distribution by hour at Winter LT5
0
0.5
1
1.5
2
2.5
EventsAverage Hourly Distribution Hourly Maximum
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Figure C-29. Geophony at Monitor Winter LT7
Figure C-30. Biophony at Monitor Winter LT7
Figure C-31. Mechanized sound at Winter LT7: Average hourly %
Figure C-32. Mechanized sound at Winter LT7: Daily hourly %
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Figure C-33. Sound Pressure Levels at Winter LT7
Figure C-34. Audible mechanized events per day at Winter LT7
Figure C-35. Audible mechanized events distribution by hour at Winter LT7
Figure C-36. Geophony at Monitor Spring LT1
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Figure C-37. Biophony at Monitor Spring LT1
Figure C-38. Mechanized sound at Spring LT1: Average hourly %
Figure C-39. Mechanized sound at Spring LT1: Daily hourly %
Figure C-40. Sound Pressure Levels at Spring LT1
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Figure C-41. Audible mechanized events per day at Spring LT1
Figure C-42. Audible mechanized events distribution by hour at Spring LT1
Figure C-43. Geophony at Monitor Spring LT2
Figure C-44. Biophony at Monitor Spring LT2
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Figure C-45. Mechanized sound at Spring LT2: Average hourly %
Figure C-46. Mechanized sound at Spring LT2: Daily hourly %
Figure C-47. Sound Pressure Levels at Spring LT2
Figure C-48. Audible mechanized events per day at Spring LT2
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Figure C-49. Audible mechanized events distribution by hour at Spring LT2
Figure C-50. Geophony at Monitor Spring LT3
Figure C-51. Biophony at Monitor Spring LT3
Figure C-52. Mechanized sound at Spring LT3: Average hourly %
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Figure C-53. Mechanized sound at Spring LT3: Daily hourly %
Figure C-54. Sound Pressure Levels at Spring LT3
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Figure C-55. Audible mechanized events per day at Spring LT3
Figure C-56. Audible mechanized events distribution by hour at Spring LT3
Figure C-57. Geophony at Monitor Spring LT4
Figure C-58. Biophony at Monitor Spring LT4
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Figure C-59. Mechanized sound at Spring LT4: Average hourly %
Figure C-60. Mechanized sound at Spring LT4: Daily hourly %
Figure C-61. Sound Pressure Levels at Spring LT4
Figure C-62. Audible mechanized events per day at Spring LT4
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Figure C-63. Audible mechanized events distribution by hour at Spring LT4
Figure C-64. Geophony at Monitor Spring LT5
Figure C-65. Biophony at Monitor Spring LT5
Figure C-66. Mechanized sound at Spring LT5: Average hourly %
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Figure C-67. Mechanized sound at Spring LT5: Daily hourly %
Figure C-68. Sound Pressure Levels at Spring LT5
Figure C-69. Audible mechanized events per day at Spring LT5
Figure C-70. Audible mechanized events distribution by hour at Spring LT5
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Figure C-71. Geophony at Monitor Spring LT6
Figure C-72. Biophony at Monitor Spring LT6
Figure C-73. Mechanized sound at Spring LT6: Average hourly %
Figure C-74. Mechanized sound at Spring LT6: Daily hourly %
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FERC Project No. 14241 Appendix C – Page 20 October 2015
Figure C-75. Sound Pressure Levels at Spring LT6
Figure C-76. Audible mechanized events per day at Spring LT6
Figure C-77. Audible mechanized events distribution by hour at Spring LT6
Figure C-78. Geophony at Monitor Spring LT7
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
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FERC Project No. 14241 Appendix C – Page 21 October 2015
Figure C-79. Biophony at Monitor Spring LT7
Figure C-80. Mechanized sound at Spring LT7: Average hourly %
Figure C-81. Mechanized sound at Spring LT7: Daily hourly %
Figure C-82. Sound Pressure Levels at Spring LT7
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FERC Project No. 14241 Appendix C – Page 22 October 2015
Figure C-83. Audible mechanized events per day at Spring LT7
Figure C-84. Audible mechanized events distribution by hour at Spring LT7
Figure C-85. Geophony at Monitor Spring LT9
Figure C-86. Biophony at Monitor Spring LT9
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FERC Project No. 14241 Appendix C – Page 23 October 2015
Figure C-87. Mechanized sound at Spring LT9: Average hourly %
Figure C-88. Mechanized sound at Spring LT9: Daily hourly %
Figure C-89. Sound Pressure Levels at Spring LT9
Figure C-90. Audible mechanized events per day at Spring LT9
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FERC Project No. 14241 Appendix C – Page 24 October 2015
Figure C-91. Audible mechanized events distribution by hour at Spring LT9
Figure C-92. Geophony at Monitor Summer LT1
Figure C-93. Biophony at Monitor Summer LT1
Figure C-94. Mechanized sound at Summer LT1: Average hourly %
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FERC Project No. 14241 Appendix C – Page 25 October 2015
Figure C-95. Mechanized sound at Summer LT1: Daily hourly %
Figure C-96. Sound Pressure Levels at Summer LT1
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FERC Project No. 14241 Appendix C – Page 26 October 2015
Figure C-97. Audible mechanized events per day at Summer LT1
Figure C-98. Audible mechanized events distribution by hour at Summer
LT1
Figure C-99. Geophony at Monitor Summer LT3
Figure C-100. Biophony at Monitor Summer LT3
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
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FERC Project No. 14241 Appendix C – Page 27 October 2015
Figure C-101. Mechanized sound at Summer LT3: Average hourly %
Figure C-102. Mechanized sound at Summer LT3: Daily hourly %
Figure C-103. Sound Pressure Levels at Summer LT3
Figure C-104. Audible mechanized events per day at Summer LT3
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FERC Project No. 14241 Appendix C – Page 28 October 2015
Figure C-105. Audible mechanized events distribution by hour at Summer LT3
Figure C-106. Geophony at Monitor Summer LT4
Figure C-107. Biophony at Monitor Summer LT4
Figure C-108. Mechanized sound at Summer LT4: Average hourly %
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FERC Project No. 14241 Appendix C – Page 29 October 2015
Figure C-109. Mechanized sound at Summer LT4: Daily hourly %
Figure C-110. Sound Pressure Levels at Summer LT4
Figure C-111. Audible mechanized events per day at Summer LT4
Figure C-112. Audible mechanized events distribution by hour at Summer
LT4
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
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FERC Project No. 14241 Appendix C – Page 30 October 2015
Figure C-113. Geophony at Monitor Summer LT5
Figure C-114. Biophony at Monitor Summer LT5
Figure C-115. Mechanized sound at Summer LT5: Average hourly %
Figure C-116. Mechanized sound at Summer LT:5 Daily hourly %
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
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FERC Project No. 14241 Appendix C – Page 31 October 2015
Figure C-117. Sound Pressure Levels at Summer LT5
Figure C-118. Audible mechanized events per day at Summer LT5
Figure C-119. Audible mechanized events distribution by hour at Summer LT5
Figure C-120. Geophony at Monitor Summer LT6
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
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FERC Project No. 14241 Appendix C – Page 32 October 2015
Figure C-121. Biophony at Monitor Summer LT6
Figure C-122. Mechanized sound at Summer LT6: Average hourly %
Figure C-123. Mechanized sound at Summer LT6: Daily hourly %
Figure C-124. Sound Pressure Levels at Summer LT6
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
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FERC Project No. 14241 Appendix C – Page 33 October 2015
Figure C-125. Audible mechanized events per day at Summer LT6
Figure C-126. Audible mechanized events distribution by hour at Summer
LT6
Figure C-127. Geophony at Monitor Summer LT7
Figure C-128. Biophony at Monitor Summer LT7
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
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FERC Project No. 14241 Appendix C – Page 34 October 2015
Figure C-129. Mechanized sound at Summer LT7: Average hourly %
Figure C-130. Mechanized sound at Summer LT7: Daily hourly %
Figure C-131. Sound Pressure Levels at Summer LT7
Figure C-132. Audible mechanized events per day at Summer LT7
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
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FERC Project No. 14241 Appendix C – Page 35 October 2015
Figure C-133. Audible mechanized events distribution by hour at Summer LT7
Figure C-134. Geophony at Monitor Summer LT8
Figure C-135. Biophony at Monitor Summer LT8
Figure C-136. Mechanized sound at Summer LT8: Average hourly %
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix C – Page 36 October 2015
Figure C-137. Mechanized sound at Summer LT8: Daily hourly %
Figure C-138. Sound Pressure Levels at Summer LT8
Figure C-139. Audible mechanized events per day at Summer LT8
Figure C-140. Audible mechanized events distribution by hour at Summer LT8
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
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FERC Project No. 14241 Appendix C – Page 37 October 2015
Figure C-141. Geophony at Monitor Summer LT9
Figure C-142. Biophony at Monitor Summer LT9
Figure C-143. Mechanized sound at Summer LT9: Average hourly %
Figure C-144. Mechanized sound at Summer LT9: Daily hourly %
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix C – Page 38 October 2015
Figure C-145. Sound Pressure Levels at Summer LT9
Figure C-146. Audible mechanized events per day at Summer LT9
Figure C-147. Audible mechanized events distribution by hour at Summer LT9
Figure C-148. Geophony at Monitor Fall LT1
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
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FERC Project No. 14241 Appendix C – Page 39 October 2015
Figure C-149. Biophony at Monitor Fall LT1
Figure C-150. Mechanized sound at Fall LT1: Daily hourly %
Figure C-151. Audible mechanized events distribution by hour at Fall LT1
Figure C-152. Sound Pressure Levels at Fall LT1
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
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FERC Project No. 14241 Appendix C – Page 40 October 2015
Figure C-153. Geophony at Monitor Fall LT 2
Figure C-154. Biophony at Monitor Fall LT2
Figure C-155. Sound Pressure Levels at Fall LT2
Figure C-156. Geophony at Monitor Fall LT3
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix C – Page 41 October 2015
Figure C-157. Biophony at Monitor Fall LT3
Figure C-158. Sound Pressure Levels at Fall LT3
Figure C-159. Geophony at Monitor Fall LT4
Figure C-160. Biophony at Monitor Fall LT4
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix C – Page 42 October 2015
Figure C-161. Mechanized sound at Fall LT4: Daily hourly %
Figure C-162. Audible mechanized events distribution by hour at Fall LT4
Figure C-163. Sound Pressure Levels at Fall LT4
Figure C-164. Geophony at Monitor Fall LT5
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix C – Page 43 October 2015
Figure C-165. Biophony at Monitor Fall LT5
Figure C-166. Mechanized sound at Fall LT5: Daily hourly %
Figure C-167. Audible mechanized events distribution by hour at Fall LT5
Figure C-168. Sound Pressure Levels at Fall LT5
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
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FERC Project No. 14241 Appendix C – Page 44 October 2015
Figure C-169. Geophony at Monitor Fall LT7
Figure C-170. Biophony at Monitor Fall LT7
Figure C-171. Mechanized sound at Fall LT7: Average hourly %
Figure C-172. Mechanized sound at Fall LT7: Daily hourly %
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
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FERC Project No. 14241 Appendix C – Page 45 October 2015
Figure C-173. Sound Pressure Levels at Fall LT7
Figure C-174. Audible mechanized events per day at Fall LT7
Figure C-175. Audible mechanized events distribution by hour at Fall LT7
Figure C-176. Geophony at Monitor Fall LT8
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
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FERC Project No. 14241 Appendix C – Page 46 October 2015
Figure C-177. Biophony at Monitor Fall LT8
Figure C-178. Mechanized sound at Fall LT8: Average hourly %
Figure C-179. Mechanized sound at Fall LT8: Daily hourly %
Figure C-180. Sound Pressure Levels at Fall LT8
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
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FERC Project No. 14241 Appendix C – Page 47 October 2015
Figure C-181. Audible mechanized events per day at Fall LT8
Figure C-182. Audible mechanized events distribution by hour at Fall LT8
Figure C-183. Geophony at Monitor Fall LT9
Figure C-184. Biophony at Monitor Fall LT9
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
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FERC Project No. 14241 Appendix C – Page 48 October 2015
Figure C-185. Mechanized sound at Fall LT9: Average hourly %
Figure C-186. Mechanized sound at Fall LT9: Daily hourly %
Figure C-187. Sound Pressure Levels at Fall LT9
Figure C-188. Audible mechanized events per day at Fall LT9
SOUNDSCAPE TECHNICAL MEMORANDUM AESTHETICS RESOURCES STUDY (12.6)
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FERC Project No. 14241 Appendix C – Page 49 October 2015
Figure C-189. Audible mechanized events distribution by hour at Fall LT9