[Federal Register Volume 83, Number 108 (Tuesday, June 5, 2018)]
[Notices]
[Pages 26013-26036]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-12043]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XG059


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to Demolition and Reuse of the 
Original East Span of the San Francisco-Oakland Bay Bridge

AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and 
Atmospheric Administration (NOAA), Commerce.

ACTION: Notice; Issuance of an incidental harassment authorization.

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SUMMARY: In accordance with the regulations implementing the Marine 
Mammal Protection Act (MMPA) as amended, notification is hereby given 
that NMFS has issued an incidental harassment authorization (IHA) to 
the California Department of Transportation (Caltrans) to incidentally 
harass, by Level B harassment only, marine mammals during the 
dismantling and reuse of the original East Span of the San Francisco-
Oakland Bay Bridge (SFOBB) in the San Francisco Bay (SFB).

DATES: This Authorization is applicable from May 24, 2018 to May 23, 
2019.

FOR FURTHER INFORMATION CONTACT: Sara Young, Office of Protected 
Resources, NMFS, (301) 427-8401. Electronic copies of the application 
and supporting documents, as well as a list of the references cited in 
this document, may be obtained online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities. In case of problems 
accessing these documents, please call the contact listed above.

SUPPLEMENTARY INFORMATION: 

Background

    Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.) 
direct the Secretary of Commerce (as delegated to NMFS) to allow, upon 
request, the incidental, but not intentional, taking of small numbers 
of marine mammals by U.S. citizens who engage in a specified activity 
(other than commercial fishing) within a specified geographical region 
if certain findings are made and either regulations are issued or, if 
the taking is limited to harassment, a notice of a proposed 
authorization is provided to the public for review.
    An authorization for incidental takings shall be granted if NMFS 
finds that the taking will have a negligible impact on the species or 
stock(s), will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for subsistence uses (where 
relevant), and if the permissible methods of taking and requirements 
pertaining to the mitigation, monitoring and reporting of such takings 
are set forth.
    NMFS has defined ``negligible impact'' in 50 CFR 216.103 as an 
impact resulting from the specified activity that cannot be reasonably 
expected to, and is not reasonably likely to, adversely affect the 
species or stock through effects on annual rates of recruitment or 
survival.
    The MMPA states that the term ``take'' means to harass, hunt, 
capture, kill or attempt to harass, hunt, capture, or kill any marine 
mammal.
    Except with respect to certain activities not pertinent here, the 
MMPA defines ``harassment'' as any act of pursuit, torment, or 
annoyance which (i) has the potential to injure a marine mammal or 
marine mammal stock in the wild (Level A harassment); or (ii) has the 
potential to disturb a marine mammal or marine mammal stock in the wild 
by causing disruption of behavioral patterns, including, but not 
limited to, migration, breathing, nursing, breeding, feeding, or 
sheltering (Level B harassment).

National Environmental Policy Act

    To comply with the National Environmental Policy Act of 1969 (NEPA; 
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A, 
NMFS reviewed our proposed action (i.e., the issuance of an incidental 
harassment authorization) with respect to potential impacts on the 
human environment.
    This action is consistent with categories of activities identified 
in Categorical Exclusion B4 (incidental harassment authorizations with 
no anticipated serious injury or mortality) of the Companion Manual for 
NOAA Administrative Order 216-6A, which do not individually or 
cumulatively have the potential for significant impacts on the quality 
of the human environment and for which we have not identified any 
extraordinary circumstances that would preclude this categorical 
exclusion. Accordingly, NMFS has determined that the issuance of the 
IHA qualifies to be categorically excluded from further NEPA review.

Summary of Request

    On January 9, 2018, NMFS received a request from Caltrans for an 
IHA to take marine mammals incidental to the demolition and reuse of 
the original East Span of the SFOBB in San Francisco Bay. Caltrans' 
request is for take of seven species of marine mammals, by Level B 
harassment. Neither Caltrans

[[Page 26014]]

nor NMFS expects serious injury or mortality to result from this 
activity and, therefore, an IHA is appropriate.
    NMFS previously issued several IHAs to Caltrans for similar work, 
with the most recent IHA issued in 2017 (82 FR 35510). Caltrans 
complied with all the requirements (e.g., mitigation, monitoring, and 
reporting) of the previous IHAs and information regarding their 
monitoring results may be found in the Effects of the Specified 
Activity on Marine Mammals and their Habitat and Estimated Take 
section. This IHA will cover one year of a larger project for which 
Caltrans obtained previous IHAs. The larger project involves 
dismantling of many piers of many remaining structures from the 
original east span of the bridge.

Description of Proposed Activity

Overview

    Caltrans proposed to demolish and reuse portions of the original 
East Span of the SFOBB by mechanical dismantling and by use of 
controlled charges to implode two piers (Piers E19 and E20) into their 
open cellular chambers below the mudline. Activities associated with 
dismantling of the piers may potentially result in incidental take of 
marine mammals due to the use of highly controlled charges to dismantle 
the marine foundations of the piers. A public access point will 
incorporate existing piers (E21, E22, and E23) but requires use of pile 
driving to finalize the access structure. Pier E2 will also be retained 
for public access improvements, but does not require any in-water work.
    Several previous one-year IHAs have been issued to Caltrans for 
pile driving/removal and construction of the new SFOBB East Span 
beginning in 2003. NMFS has issued 11 IHAs to Caltrans for the SFOBB 
Project. The first five IHAs (2003, 2005, 2007, 2009, and 2011) 
addressed potential impacts associated with pile driving for the 
construction of the new East Span of the SFOBB. IHAs issued in 2013, 
2014 and July 2015 addressed activities associated with both 
constructing the new East Span and dismantling the original East Span, 
specifically addressing vibratory pile driving, vibratory pile 
extraction/removal, attenuated impact pile driving, pile proof testing, 
and mechanical dismantling of temporary and permanent marine 
foundations. On September 9, 2015, NMFS issued an IHA to Caltrans for 
incidental take associated with the demolition of Pier E3 of the 
original SFOBB by highly controlled explosives (80 FR 57584; September 
24, 2015). On September 30, 2016, NMFS issued an IHA authorizing the 
incidental take of marine mammals associated with both pile driving/
removal and controlled implosion of Piers E4 and E5 (81 FR 67313). On 
July 13, 2017, NMFS issued an IHA (82 FR 35510, July 31, 2017) to 
Caltrans authorizing take of marine mammals for additional dismantling 
the original East Span of the SFOBB using mechanical means as well as 5 
to 6 implosion events to dismantle 13 piers (Piers E6-E18). This year 
of work will include removal of Piers E19 and E20.

Dates and Duration

    Vibratory pile driving for construction of the Oakland Touchdown 
pedestrian bridge (OTD) and OTD access trestle may begin in June 2018. 
Impact pile-driving activities will be restricted from June 1 to 
November 30, to avoid peak salmonid migration periods. Pier implosion 
requiring IHA coverage is scheduled to begin in September 2018. Pier 
implosion will be restricted from September 1 to November 30, to 
minimize potential impacts on biological resources in the Bay.

Specific Geographic Region

    The SFOBB project area is located in the central SFB or Bay, 
between Yerba Buena Island (YBI) and the city of Oakland. The western 
limit of the project area is the east portal of the YBI tunnel, located 
in the city of San Francisco. The eastern limit of the project area is 
located approximately 1,312 feet (400 meters) west of the Bay Bridge 
toll plaza, where the new and former spans of the bridge connect with 
land at the OTD in the city of Oakland. The approximate width of the 
in-water work area is 350 meters (1,148 feet). This includes all in-
water areas under the original bridge and new bridge. All activities 
proposed under this IHA application will be confined to this area. 
However, other previous in-water project activities have taken place in 
discrete areas near both YBI and Treasure Island outside these limits.

Detailed Description of Specific Activity

    Construction activities associated with both dismantling and reuse 
of marine foundations of the original east span bridge may result in 
the incidental take of marine mammals. These activities include the use 
of highly controlled charges to dismantle Piers E19 and E20, as well as 
pile-driving activities associated with construction of a public access 
facility that will incorporate reuse Piers E21, E22 and E23. Pier E2 
will also be retained and incorporated into a public access facility. 
However, public access improvements at Pier E2 will not require any in-
water work and will not result in incidental take of marine mammals; 
therefore, are not discussed further.
Removal of Piers 19 and 20
    The removal of Piers E19 and E20 will be performed in three phases. 
The first phase will use mechanical dismantling to remove the above-
water portions of the piers, which is not expected to result in take. 
The second phase will use controlled blasting methods for removal of 
the in-water portions of the piers. The third phase will include 
dredging of imploded rubble to specified removal limits, which is also 
not expected to result in take. Limits of removal will be determined at 
each location and will result in removal to between 0.46 and 0.91 meter 
(1.5 and 3 feet) below the mudline.
    Piers E19 and E20 are large cellular structures through the water 
column, which are supported on concrete slabs and hundreds of driven 
timber piles encased in a concrete seal. The timber piles and concrete 
seal courses that are below approved removal limits will remain in 
place. Rubble that mounds above the determined debris removal elevation 
limits from the dismantling of these piers will be removed off-site for 
disposal; as was done during the removal of Piers E6 to E18.
    A Blast Attenuation System (BAS) similar to that used for previous 
blast events will be used during all future controlled blasting events, 
to minimize potential impacts on biological resources in the Bay. The 
effectiveness of this minimization measure is supported by the findings 
from the successful removal of Piers E3 to E18.
    Each pier will be removed in the following three phases:
     Pre-blasting activities, including removing the pier cap 
and concrete pedestals, installing and testing the BAS;
     installing charges, activating the BAS, and imploding the 
pier; and
     dredging of imploded rubble to specified removal limits.
    Further detail on the above steps to remove the marine foundations 
are provided. Phase 1: Dismantling the concrete pedestals and concrete 
pier cap by mechanical means (including the use of torches and 
excavators mounted with hoe rams, drills, and cutting tools), and 
drilling vertical boreholes where the charges will be loaded for 
controlled blasting. Phase 2: The charges then will be loaded into the 
drilled boreholes. Controlled blasting removal will be accomplished 
using hundreds of small charges, with delays between individual

[[Page 26015]]

charges. The controlled blast sequence for each pier will last 
approximately 1 to 5 seconds. The controlled blast removals have been 
designed to remove each pier to between 0.46 and 0.91 meter (1.5 and 3 
feet) below the mudline. Phase 3: Dredging of imploded rubble to 
specified removal limits.
Blast Attenuation System Testing, Installation, and Deployment
    The BAS will be deployed around each pier being imploded and will 
be the same system as that successfully used for the removal of Piers 
E3 to E18. The BAS is a modular system of pipe manifold frames, placed 
around each pier and fed by air compressors to create a curtain of air 
bubbles. Each BAS frame is approximately 15.4 meters long by 1.8 meters 
wide (50.5 feet long by 6 feet wide). The BAS to be used will be the 
same design that was used at Piers E3 to E18 and will meet the same 
specifications. The BAS will be activated before and during implosion. 
As shown during the Pier E3 Demonstration Project and eight subsequent 
pier blast events by the SFOBB Project, the BAS will attenuate noise 
and pressure waves generated during each controlled blast, to minimize 
potentially adverse effects on biological resources that may be nearby.
    Before installing the BAS, Caltrans will move any existing debris 
on the Bay floor that may interrupt or conflict with proper 
installation of the BAS. Each BAS frame will be lowered to the bottom 
of the Bay by a barge-mounted crane and will be positioned into place. 
Divers will assist frame placement and will the connect air hoses to 
the frames. Based on location around the pier, the BAS frame elements 
will be situated from approximately 8 to 12 meters (25 to 40 feet) from 
the outside edge of each pier. The frames will be situated to 
contiguously surround each pier. Frame ends will overlap to ensure no 
break in the BAS when operational. Each frame will be weighted to 
negative buoyancy for activation. Compressors will provide enough 
pressure to achieve a minimal air volume fraction of 3 to 4 percent, 
consistent with the successful use of BAS systems in past controlled 
blasting activities.
    The complete BAS will be installed and tested during the weeks 
leading up to the controlled blast. The BAS test parameters will 
include checking operating levels, flow rate, and a visual check to 
determine that the system is operating correctly. System performance is 
anticipated to provide approximately 80 percent noise and pressure 
attenuation, based on the results from the previous SFOBB Project blast 
events using a similar system.
    Test blasts may be conducted to ensure that the hydroacoustic 
monitoring equipment will be functional and triggered properly before 
the pier implosion event. The test blasts will be conducted within the 
completely installed and operating BAS. A key requirement of pier 
implosion will involve accurately capturing hydroacoustic information 
from the controlled blast. To accomplish this, a smaller test charge 
will be used to trigger recording instrumentation. Multiple test blasts 
on the same day may be required to verify proper instrument operation 
and calibrate the equipment for the implosion events. These same 
instruments and others of the same type will use high-speed recording 
devices to capture hydroacoustic data at both near-field and far-field 
monitoring locations during the implosion.
    Test blasts will be scheduled to occur within two weeks of the 
scheduled implosion. Tests will use a charge weight of approximately 18 
grains (0.0025 pound) or less and will be placed along one of the 
longer faces of the pier. The results from test blasts that occurred 
before the implosions of Pier E3 and E5 indicate that these test blasts 
will have minimal impacts on fish and no impacts on marine mammals (see 
Appendix A in application).
    Piers E19 and E20 will be imploded during a single event. Before 
pier removal via controlled blasting, Caltrans will load the bore holes 
of the piers with controlled charges. Individual cartridge charges 
using electronic blasting caps have been selected to provide greater 
control and accuracy in determining the individual and total charge 
weights. Use of individual cartridges will allow a refined blast plan 
that efficiently breaks concrete while minimizing the amount of charges 
needed.
    Boreholes will vary in diameter and depth, and have been designed 
to provide optimal efficiency in transferring the energy created by the 
controlled charges to dismantle the piers. Individual charge weights 
will vary from 7 to 11 kilograms (15 to 25 pounds), and the total 
charge weight for the Pier E19 and E20 blast event will be 
approximately 1,800 kilograms (4,000 pounds). The total number of 
individual charges to be used per pier will be approximately 100. 
Charges will be arranged in different levels (decks) and will be 
separated in the boreholes by stemming. Stemming is the insertion of 
inert materials (e.g., sand or gravel) to insulate and retain charges 
in an enclosed space. Stemming allows more efficient transfer of energy 
into the structural concrete for fracture, and further reduces the 
release of potential energy into the surrounding water column. The 
entire detonation sequence, consisting of approximately 200 
detonations, will last approximately 1 to 5 seconds for each pier; with 
a minimum delay time of 9 milliseconds (msec) between detonations. 
There will be approximately half a second delay between pier blasts to 
avoid overlap of pressure waves.
    Piers E19 and E20 will be blasted in a single pier implosion event. 
These piers will be removed by blasting down through the concrete 
cellular structure but not through the concrete slab, seal, and timber 
piles below. Remaining concrete seals and timber piles below the 
mudline will not be removed.
Reuse of Piers E21 to E23
    A pedestrian bridge and observation platforms, will be constructed 
near the Oakland shoreline, using the existing marine foundations as 
anchors for this public access facility. Construction of this facility 
at Piers E21 to E23 (Oakland side) will require mechanical removal of 
some or perhaps all of the pedestals and pier slabs to elevations 
required by the design. Both temporary and permanent piles will be 
needed for construction of this pedestrian bridge and observation 
platforms.
    The OTD pedestrian bridge will extend from Pier E23 on the Oakland 
shoreline to Pier E21. It will be supported by Piers E23, E22, and E21. 
Observation areas also may be constructed at Piers E22 and E21. 
Reinforced concrete slabs may be constructed on top of Piers E22 and 
E21, to serve as an observation platforms. The existing pier 
foundations are spaced 88 meters (290 feet) apart. New intermediate 
piers will be constructed between the existing pier foundations to 
support the pedestrian bridge. These permanent intermediate piers will 
be pile-supported.
    A temporary access trestle also may also be needed to facilitate 
construction of the pedestrian bridge. This temporary access trestle 
will be pile-supported.
    Both the pedestrian bridge and temporary access trestle will be 
designed by the construction contractor. Because these structures will 
be contractor-designed, their exact nature (e.g., size, type, number of 
piles) will not be known until construction begins. However, the 
Caltrans has developed a conservative estimate as to the approximate 
type, size, and number of piles needed for these proposed structures. 
Up to 200 in-water piles may be required for construction of the OTD

[[Page 26016]]

pedestrian bridge and temporary access trestle. Caltrans originally 
proposed concrete piles as a possibility but has determined concrete 
piles will not be used for this work and reference to concrete piles 
has been removed from the remainder of the document. Piles may be steel 
pipe piles or H-piles. The steel pipe piles will be 24 to 36 inches in 
diameter, or less. In-water pile driving for construction of the 
pedestrian bridge and temporary access trestle may result in the 
incidental harassment of marine mammals.
    Mitigation, monitoring, and reporting measures are described in 
detail later in this document (please see ``Mitigation'' and 
``Monitoring and Reporting'').

Comments and Responses

    A notice of NMFS's proposal to issue an IHA to Caltrans was 
published in the Federal Register on April 12, 2018 (83 FR 15795). That 
notice described, in detail, Caltrans' activity, the marine mammal 
species that may be affected by the activity, and the anticipated 
effects on marine mammals. During the 30-day public comment period, 
NMFS received comments from the Marine Mammal Commission. The Marine 
Mammal Commission submitted the following comments to NMFS.
    Comment 1: The Commission noted various errors in the proposed 
authorization, including errors in the description of the action and 
the effects analyses. The Commission recommends that NMFS review its 
notices more thoroughly before submitting for publication.
    Response 1: NMFS thanks the Commission for pointing out the errors 
in the Federal Register Notice for the proposed authorization. To 
address errors in the description and effects analyses, NMFS is 
reprinting these sections in the Federal Register notice for the 
issuance of the authorization, with the errors corrected. NMFS makes 
every effort to read the notices thoroughly prior to publication and 
will continue this effort to publish the best possible product for 
public comment.
    Comment 2: The Commission recommends that NMFS refrain from using a 
source level reduction factor for sound attenuation device 
implementation during impact pile driving for all relevant incidental 
take authorizations due to the different noise level reduction at 
different received ranges.
    Response 2: While it is true that noise level reduction measured at 
different received ranges does vary, given that both Level A and Level 
B estimation using geometric modeling is based on noise levels measured 
at near-source distances (~10 m), NMFS believes it reasonable to use a 
source level reduction factor for sound attenuation device 
implementation during impact pile driving. In the case of the SFOBB 
impact driving isopleth estimates using an air bubble curtain for 
source level reduction, NMFS reviewed Caltrans' bubble curtain ``on and 
off'' studies conducted in San Francisco Bay in 2003 and 2004. The 
equipment used for bubble curtains has likely improved since 2004 but 
due to concerns for fish species, Caltrans has not able to conduct ``on 
and off'' tests recently. Based on 74 measurements (37 with the bubble 
curtain on and 37 with the bubble curtain off) at both near (<100 m) 
and far (>100 m) distances, the linear averaged received level 
reduction is 6 dB. If limiting the data points (a total of 28 
measurements, with 14 during bubble curtain on and 14 during bubble 
curtain off) to only near distance measurements, the linear averaged 
noise level reduction is 7 dB. Based on this analysis, we conclude that 
there is not a significant difference of source level reduction between 
near and far-distance measurements. As a conservative approach, NMFS 
used the reduction of 7 dB of the source level for impact zone 
estimates.
    NMFS will evaluate the appropriateness of using a certain source 
level reduction factor for sound attenuation device implementation 
during impact pile driving for all relevant incidental take 
authorizations when more data become available. Nevertheless at this 
point, we think it appropriate that a conservative 6 dB reduction is 
reasonable to be used as a source level reduction factor for impact 
pile driving using an air bubble curtain system.
    Comment 3: The Commission recommends that NMFS promptly revise its 
draft rounding criteria and share it with the Commission.
    Response 3: NMFS appreciates the Commission's ongoing concern in 
this matter. Calculating predicted takes is not an exact science and 
there are arguments for taking different mathematical approaches in 
different situations, and for making qualitative adjustments in other 
situations. We believe, however, that the methodology used for take 
calculation in this IHA remains appropriate and is not at odds with the 
24-hour reset policy the Commission references. We look forward to 
continued discussion with the Commission on this matter and will share 
the rounding guidance as soon as it is ready for public review.
    Comment 4: The Commission recommends that NMFS refrain from 
implementing its proposed renewal process and use abbreviated Federal 
Register notices and reference existing documents to aid in 
streamlining. It also recommends that NMFS provide the Commission and 
the public with a legal analysis supporting use of the renewal process.
    Response 4: The process of issuing a renewal IHA does not bypass 
the public notice and comment requirements of the MMPA. The notice of 
the proposed IHA expressly notifies the public that under certain, 
limited conditions an applicant could seek a renewal IHA for an 
additional year. The notice describes the conditions under which such a 
renewal request could be considered and expressly seeks public comment 
in the event such a renewal is sought. Importantly, such renewals would 
be limited to circumstances where: The activities are identical or 
nearly identical to those analyzed in the proposed IHA; monitoring does 
not indicate impacts that were not previously analyzed and authorized; 
and, the mitigation and monitoring requirements remain the same, all of 
which allow the public to comment on the appropriateness and effects of 
a renewal at the same time the public provides comments on the initial 
IHA. NMFS has, however, modified the language for future proposed IHAs 
to clarify that all IHAs, including renewal IHAs, are valid for no more 
than one year and that the agency would consider only one renewal for a 
project at this time. In addition, notice of issuance or denial of a 
renewal IHA would be published in the Federal Register, as they are for 
all IHAs. Last, NMFS will publish on our website a description of the 
renewal process before any renewal is issued utilizing the new process.

Description of Marine Mammals in the Area of Specified Activities

    Sections 3 and 4 of the application summarize available information 
regarding status and trends, distribution and habitat preferences, and 
behavior and life history, of the potentially affected species. 
Additional information regarding population trends and threats may be 
found in NMFS's Stock Assessment Reports (SAR; www.nmfs.noaa.gov/pr/sars/) and more general information about these species (e.g., physical 
and behavioral descriptions) may be found on NMFS's website 
(www.nmfs.noaa.gov/pr/species/mammals/).
    Table 1 lists all species with expected potential for occurrence in 
San Francisco Bay and summarizes information related to the population 
or stock, including regulatory status under

[[Page 26017]]

the MMPA and ESA and potential biological removal (PBR), where known. 
For taxonomy, we follow Committee on Taxonomy (2016). PBR is defined by 
the MMPA as the maximum number of animals, not including natural 
mortalities, that may be removed from a marine mammal stock while 
allowing that stock to reach or maintain its optimum sustainable 
population (as described in NMFS's SARs). While no mortality is 
anticipated or authorized here, PBR and annual serious injury and 
mortality from anthropogenic sources are included here as gross 
indicators of the status of the species and other threats.
    Marine mammal abundance estimates presented in this document 
represent the total number of individuals that make up a given stock or 
the total number estimated within a particular study or survey area. 
NMFS's stock abundance estimates for most species represent the total 
estimate of individuals within the geographic area, if known, that 
comprises that stock. For some species, this geographic area may extend 
beyond U.S. waters. All managed stocks in this region are assessed in 
NMFS's U.S. 2016 SARs (Carretta et al., 2017). All values presented in 
Table 1 are the most recent available at the time of publication and 
are available in the 2016 SARs (Carretta et al., 2017) (available 
online at: www.nmfs.noaa.gov/pr/sars/draft.htm).

                                            Table 1--Marine Mammal Species that May Occur in the Action Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                      ESA/MMPA status;   Stock abundance (CV,
            Common name                  Scientific name              Stock           strategic (Y/N)      Nmin, most recent        PBR      Annual M/SI
                                                                                            \1\          abundance survey) \2\                   \3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                  Family Eschrichtiidae
--------------------------------------------------------------------------------------------------------------------------------------------------------
Gray whale.........................  Eschrichtius robustus.  Eastern North Pacific.  -; N.............  20,990 (0.05, 20,125,           624          132
                                                                                                         2011).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                            Family Balaenopteridae (rorquals)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Fin Whale..........................  Balaenoptera physalus.  California/Oregon/      E;Y..............  9,029 (0.12, 8,127,              81            2
                                                              Washington.                                2014).
Humpback Whale.....................  Megaptera novaeangliae  California/Oregon/      E;Y..............  1,918 (.03, 1,876,               11          6.5
                                                              Washington.                                2014).
Minke Whale........................  Balaenoptera            California/Oregon/      -; N.............  636 (0.72, 369, 2014).          3.5          1.3
                                      acutorostrata.          Washington.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                   Family Physeteridae
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sperm whale........................  Physeter macrocephalus  California/Oregon/      E;Y..............  2,106 (0.58, 1,332,             2.7          1.7
                                                              Washington.                                2008).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                   Family Delphinidae
--------------------------------------------------------------------------------------------------------------------------------------------------------
Common Bottlenose Dolphin..........  Tursiops truncatus....  California Coastal....  -; N.............  453 (0.06, 346, 2011).          2.7            2
Short-Beaked Common Dolphin........  Delphinus delphis.....  California/Oregon/....  -; N.............  969,861 (0.17,                8,393           40
                                                                                                         839,325, 2014).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                             Family Phocoenidae (porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Harbor Porpoise....................  Phocoena phocoena.....  San Francisco-Russian   -; N.............  9,886 (0.51, 6,625,              66            0
                                                              River.                                     2011).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                      Family Otariidae (eared seals and sea lions)
--------------------------------------------------------------------------------------------------------------------------------------------------------
California Sea Lion................  Zalophus californianus  United States.........  -; N.............  296,750 (N/A, 153,337,        9,200          389
                                                                                                         2011).
Northern Fur Seal..................  Callorhinus ursinus...  California, Eastern     -; N.............  14,050 (N/A, 7,524,             451          1.8
                                                              North Pacific.                             2013).
Steller sea lion...................  Eumetopias jubatus....  Eastern...............  T; D.............  41,638 (N/A, 41,638,          2,498          108
                                                                                                         2015).
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                                                             Family Phocidae (earless seals)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Harbor seal........................  Phoca vitulina........  California............  -; N.............  30,968 (N/A, 27,348,          1,641           43
                                                                                                         2012).
Northern Elephant Seal.............  Mirounga                California Breeding...  -; N.............  179,000 (N/A, 81,368,           542          3.2
                                      angustirostris.                                                    2010).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: www.nmfs.noaa.gov/pr/sars/. CV is coefficient of variation; Nmin is the minimum estimate of
  stock abundance. In some cases, CV is not applicable [explain if this is the case]
\3\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
  commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV
  associated with estimated mortality due to commercial fisheries is presented in some cases.
Note: Italicized species are not expected to be taken or proposed for authorization.


[[Page 26018]]

    All species that could potentially occur in the activity areas are 
included in Table 1. However, the temporal or spatial occurrence of the 
species italicized in Table 1 is such that take is not expected to 
occur, and they are not discussed further beyond the explanation 
provided here. San Francisco Bay would be considered extralimital and 
these species have not been sighted during marine mammal monitoring 
conducted by Caltrans under past IHAs.

Harbor Seal

    Harbor seals are found from Baja California to the eastern Aleutian 
Islands of Alaska. The species primarily hauls out on remote mainland 
and island beaches and reefs, and estuary areas. Harbor seal tends to 
forage locally within 53 miles (85 kilometers) of haul out sites 
(Harvey and Goley 2011). Harbor seal is the most common marine mammal 
species observed in the Bay and also commonly is seen near the SFOBB 
east span (Department 2013b, 2013c). Tagging studies have shown that 
most seals tagged in the Bay remain in the Bay (Harvey and Goley 2011; 
Manugian 2013). Foraging often occurs in the Bay, as noted by 
observations of seals exhibiting foraging behavior (short dives less 
than 5 minutes, moving back and forth in an area, and sometimes tearing 
up prey at the surface).
    The molt occurs from May through June. During both pupping and molt 
seasons, the number of seals and the length of time hauled out per day 
increases, with about 60.5 percent of the population hauled out during 
this time versus less than 20 percent in fall (Yochem et al., 1987; 
Huber et al., 2001; Harvey and Goley 2011). Mother-pup pairs spend more 
time on shore; therefore, the percentage of seals on shore at haul out 
sites increases during the pupping season (Stewart and Yochem 1994). 
Peak numbers of harbor seals hauling out in central California occurs 
during late May to early June, which coincides with the peak of their 
molt. Seals haul out more often and spend more time on shore to molt. 
Yochem et al. (1987) found that harbor seals at San Miguel Island only 
hauled out 11 to 19 percent of the time in fall, from late October 
through early December.
    Harbor seal tends to forage at night and haul out during the day. 
Harbor seal predominately hauls out from 10 a.m. to 7 p.m., with a peak 
in the afternoon between 1 and 4 p.m. (Yochem et al., 1987; Stewart and 
Yochem 1994; Grigg et al., 2002; London et al., 2012). Harbor seals in 
the Bay typically haul out in groups ranging from a few individuals to 
several hundred seals. One known haul out site is on the southern side 
of YBI, approximately 1,600 meters (5,250 feet) from Pier E6 and 
approximately 2,800 meters (9,190 feet) from Pier E18. The YBI haul out 
site had a daily range of zero to 109 harbor seals hauled out during 
September, October, and November, with the highest numbers hauled out 
during afternoon low tides (Department 2004b). Pile driving for the 
SFOBB was not audible to the monitors just above the haul out site, and 
no response to pile driving was observed.
    Tide level also can affect haul out behavior, by exposing and 
submerging preferred haul out sites. Tides likely affect the maximum 
number of seals hauled out, but time of day and the season have the 
greatest influence on haul out behavior (Stewart and Yochem 1994; 
Patterson and Acevedo-Guti[eacute]rrez 2008).
    Harbor seals in the Bay are an isolated population, although about 
40 percent may move a short distance out of the Bay to forage (Manugian 
et al. 2017). The Bay harbor seals likely are accustomed to a noisy 
environment because of construction, vessel traffic, the Bay Area Rapid 
Transit (BART) Transbay Tube, and mechanical noise (i.e., machinery, 
generators).
    During 251 days of SFOBB monitoring from 2000 through 2016, 958 
harbor seals were observed in the vicinity of the SFOBB east span. 
Harbor seals made up 90 percent of the marine mammals observed during 
monitoring for the SFOBB Project. In 2015 and 2016, the number of 
harbor seals sighted in the project area increased (8 days of 
monitoring and 95 sightings). Foraging near the project area was 
common, particularly in the coves adjacent to the YBI United States 
Coast Guard Station and in Clipper Cove between YBI and Treasure 
Island. Foraging also occurred in a shallow trench area southeast of 
YBI (Department 2013a, 2013b). These sites are more than 900 to 1,525 
meters (3,000 to 5,000 feet) west of Pier E6. In 2015, juvenile harbor 
seals began foraging around Piers E2W and E2E of the new SFOBB east 
span, and in 2016, they extended east around Piers E3 to E5 of the new 
SFOBB east span. Foraging can occur throughout the Bay, and prey 
abundance and distribution affect where harbor seals will forage. Most 
of the harbor seal sightings were animals transiting the area, likely 
moving from haul out sites or from foraging areas.

California Sea Lion

    California sea lion breeds on the offshore islands of California 
from May through July (Heath and Perrin 2008). During the non-breeding 
season, adult and sub-adult males and juveniles migrate northward along 
the coast, to central and northern California, Oregon, Washington, and 
Vancouver Island (Jefferson et al., 1993). They return south the 
following spring (Lowry and Forney 2005; Heath and Perrin 2008). 
Females and some juveniles tend to remain closer to rookeries 
(Antonelis et al., 1990; Melin et al., 2008).
    California sea lions have been observed occupying docks near Pier 
39 in San Francisco, about 3.2 miles (5.2 kilometers) from the project 
area, since 1987. The highest number of sea lions recorded at Pier 39 
was 1,701 individuals in November 2009 (De Rango, pers. comm., 2013). 
Occurrence of sea lions here typically is lowest in June (breeding 
season) and highest in August. Approximately 85 percent of the animals 
that haul out at this site are males, and no pupping has been observed 
here or at any other site in the Bay (Lander, pers. comm., 1999). Pier 
39 is the only regularly used haul out site in the project vicinity, 
but sea lions occasionally haul out on human-made structures, such as 
bridge piers, jetties, or navigation buoys (Riedman 1990).
    During monitoring for the SFOBB Project, 80 California sea lions 
were observed from 2000 through 2016. The number of sea lions that were 
sighted in the project area decreased in 2015 and 2016. Sea lions 
appear mainly to be transiting through the project area rather than 
feeding, although two exceptions have occurred. In 2004, several sea 
lions were observed following a school of Pacific herring that moved 
through the project area, and one sea lion was observed eating a large 
fish in 2015.
    Breeding and pupping occur from mid to late May until late July. 
After the mating season, adult males migrate northward to feeding areas 
as far away as the Gulf of Alaska (Lowry et al., 1992), and they remain 
away until spring (March-May), when they migrate back to the breeding 
colonies. Adult females remain near the rookeries throughout the year 
and alternate between foraging and nursing their pups on shore until 
the next pupping/breeding season.

Northern Elephant Seal

    Northern elephant seal is common on California coastal mainland and 
island sites, where the species pups, breeds, rests, and molts. The 
largest rookeries are on San Nicolas and San Miguel islands in the 
northern Channel Islands. Near the Bay, elephant seals breed, molt, and 
haul out at A[ntilde]o Nuevo Island, the Farallon Islands, and Point 
Reyes National Seashore.

[[Page 26019]]

    Northern elephant seals haul out to give birth and breed from 
December through March. Pups remain onshore or in adjacent shallow 
water through May. Both sexes make two foraging migrations each year: 
One after breeding and the second after molting (Stewart 1989; Stewart 
and DeLong 1995). Adult females migrate to the central North Pacific to 
forage, and males migrate to the Gulf of Alaska to forage (Robinson et 
al. 2012). Pup mortality is high when they make the first trip to sea 
in May, and this period correlates with the time of most strandings. 
Pups of the year return in the late summer and fall, to haul out at 
breeding rookery and small haul out sites, but occasionally they may 
make brief stops in the Bay.
    Generally, only juvenile elephant seals enter the Bay and do not 
remain long. The most recent sighting near the project area was in 
2012, on the beach at Clipper Cove on Treasure Island, when a healthy 
yearling elephant seal hauled out for approximately 1 day. 
Approximately 100 juvenile northern elephant seals strand in or near 
the Bay each year, including individual strandings at YBI and Treasure 
Island (less than 10 strandings per year).

Northern Fur Seal

    Northern fur seal breeds on the offshore islands of California and 
in the Bering Sea from May through July. Two stocks of Northern fur 
seals may occur near the Bay, the California and Eastern Pacific 
stocks. The California stock breeds, pups, and forages off the 
California coast. The Eastern Pacific stock breeds and pups on islands 
in the Bearing Sea, but females and juveniles move south to California 
waters to forage in the fall and winter months.
    Both the California and Eastern Pacific stocks forage in the 
offshore waters of California, but only sick, emaciated, or injured fur 
seals enter the Bay. The Marine Mammal Center (TMMC) occasionally picks 
up stranded fur seals around YBI and Treasure Island. The rare 
occurrence of northern fur seal near the SFOBB east span makes it 
unlikely that the species will be exposed to implosion activities.

Bottlenose Dolphin

    This species is found within 0.6 mile (1 kilometer) of shore and 
occurs from northern Baja California, Mexico to Bodega Bay, with the 
range extending north over the last several decades related to El 
Ni[ntilde]o events and increased ocean temperatures. As the range of 
bottlenose dolphins extended north, dolphins began entering the Bay in 
2010 (Szczepaniak 2013). Until 2016, most bottlenose dolphins in the 
Bay were observed in the western Bay, from the Golden Gate Bridge to 
Oyster Point and Redwood City, although one individual was observed 
frequently near the former Alameda Air Station (Perlman 2017). In 2017, 
two individuals have been observed regularly near Alameda (Keener, 
pers. comm., 2017) and likely passed by the project area.

Harbor Porpoise

    This species seldom is found in waters warmer than 62.6 degrees 
Fahrenheit (17 degrees Celsius) (Read 1990) or south of Point 
Conception, and occurs as far north as the Bering Sea (Barlow and Hanan 
1995; Carretta et al., 2009; Carretta et al., 2012; Allen and Angliss 
2013). The San Francisco-Russian River stock is found from Pescadero, 
18 miles (30 kilometers) south of the Bay, to 99 miles (160 kilometers) 
north of the Bay at Point Arena (Carretta et al., 2012). In most areas, 
harbor porpoise occurs in small groups, consisting of just a few 
individuals.
    Harbor porpoises are seen frequently outside the Bay, and they 
began to re-enter the Bay in 2008. Keener et al. (2012) reports 
sightings of harbor porpoises from just inside the Bay, northeast to 
Tiburon and south to the SFOBB west span. In 17 years of monitoring in 
the project area, 24 harbor porpoises have been observed, and all 
occurred between 2006 and 2015; including two in 2014, five in 2015 and 
15 in 2017. In 2017, the number of harbor porpoises in the project area 
increased significantly. However, the majority of harbor porpoise 
observations made during monitoring for the SFOBB Project have been at 
distances ranging from 2,438 to 3,048 meters (8,000 to 10,000 feet) 
from the work area.

Gray Whale

    The eastern North Pacific population of gray whales ranges from the 
southern tip of Baja California, Mexico to the Chukchi and Beaufort 
Seas (Jefferson et al., 1993). The gray whale makes a well-defined, 
seasonal north-south migration. Most of the population summers in the 
shallow waters of the northern Bering Sea, the Chukchi Sea, and the 
western Beaufort Sea (Rice and Wolman 1971). However, some individuals 
also summer along the Pacific coast, from Vancouver Island to central 
California (Rice and Wolman 1971; Darling 1984; Nerini 1984). In 
October and November, gray whales begin to migrate south and follow the 
shoreline to breeding grounds along the western coast of Baja 
California and the southeastern Gulf of California (Braham 1984). Gray 
whales begin heading north in late winter and early spring (Rice and 
Wolman 1971). The average gray whale migrates 4,660 to 6,213 miles 
(7,500 to 10,000 kilometers), at a rate of 91 miles/day (147 
kilometers/day) (Jones and Swartz 2002). Gray whales generally calve 
and breed during the winter, in lagoons in Baja California (Jones and 
Swartz 2002), although some calves are born along the California coast 
during the migration south.

Marine Mammal Hearing

    Hearing is the most important sensory modality for marine mammals 
underwater, and exposure to anthropogenic sound can have deleterious 
effects. To appropriately assess the potential effects of exposure to 
sound, it is necessary to understand the frequency ranges marine 
mammals are able to hear. Current data indicate that not all marine 
mammal species have equal hearing capabilities (e.g., Richardson et 
al., 1995; Wartzok and Ketten, 1999; Au and Hastings 2008). To reflect 
this, Southall et al. (2007) recommended that marine mammals be divided 
into functional hearing groups based on directly measured or estimated 
hearing ranges on the basis of available behavioral response data, 
audiograms derived using auditory evoked potential techniques, 
anatomical modeling, and other data. Note that no direct measurements 
of hearing ability have been successfully completed for mysticetes 
(i.e., low-frequency cetaceans). Subsequently, NMFS (2016) described 
generalized hearing ranges for these marine mammal hearing groups. 
Generalized hearing ranges were chosen based on the approximately 65 dB 
threshold from the normalized composite audiograms, with the exception 
for lower limits for low-frequency cetaceans where the lower bound was 
deemed to be biologically implausible and the lower bound from Southall 
et al. (2007) retained. The functional groups and the associated 
frequencies are indicated below (note that these frequency ranges 
correspond to the range for the composite group, with the entire range 
not necessarily reflecting the capabilities of every species within 
that group):
     Low-frequency cetaceans (mysticetes): Generalized hearing 
is estimated to occur between approximately 7 hertz (Hz) and 35 
kilohertz (kHz);
     Mid-frequency cetaceans (larger toothed whales, beaked 
whales, and most delphinids): Generalized hearing is estimated to occur 
between approximately 150 Hz and 160 kHz;
     High-frequency cetaceans (porpoises, river dolphins, and 
members

[[Page 26020]]

of the genera Kogia and Cephalorhynchus; including two members of the 
genus Lagenorhynchus, on the basis of recent echolocation data and 
genetic data): Generalized hearing is estimated to occur between 
approximately 275 Hz and 160 kHz.
     Pinnipeds in water; Phocidae (true seals): Generalized 
hearing is estimated to occur between approximately 50 Hz to 86 kHz;
     Pinnipeds in water; Otariidae (eared seals): Generalized 
hearing is estimated to occur between 60 Hz and 39 kHz.
    The pinniped functional hearing group was modified from Southall et 
al. (2007) on the basis of data indicating that phocid species have 
consistently demonstrated an extended frequency range of hearing 
compared to otariids, especially in the higher frequency range 
(Hemil[auml] et al., 2006; Kastelein et al., 2009; Reichmuth and Holt, 
2013).
    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2016) for a review of available information. 
seven marine mammal species (three cetacean and four pinniped (three 
otariid and one phocid) species) have the reasonable potential to co-
occur with the construction activities. Please refer to Table 1. Of the 
cetacean species that may be present, one is classified as low-
frequency cetaceans (gray whale), one is classified as mid-frequency 
cetaceans (bottlenose dolphin), and one is classified as high-frequency 
cetaceans (harbor porpoise).

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    This section includes a summary and discussion of the ways that 
components of the specified activity may impact marine mammals and 
their habitat. The ``Estimated Take by Incidental Harassment'' section 
later in this document includes a quantitative analysis of the number 
of individuals that are expected to be taken by this activity. The 
``Negligible Impact Analysis and Determination'' section considers the 
content of this section, the ``Estimated Take by Incidental 
Harassment'' section, and the ``Mitigation'' section, to draw 
conclusions regarding the likely impacts of these activities on the 
reproductive success or survivorship of individuals and how those 
impacts on individuals are likely to impact marine mammal species or 
stocks.

General Information on Potential Effects

    Explosives are impulsive sounds, which are characterized by short 
duration, abrupt onset, and rapid decay. The Caltrans SFOBB work using 
controlled charges (i.e., implosion events) could adversely affect 
marine mammal species and stocks by exposing them to elevated noise 
levels in the vicinity of the activity area. Based on the nature of the 
other activities associated with the dismantling of Piers E6 through 
E18 of the original SFOBB East Span (mechanical dismantling) and 
measured sound levels from those activities during past monitoring 
associated with previous IHAs, NMFS does not expect activities other 
than implosion events to contribute to underwater noise levels such 
that take of marine mammals will potentially occur.
    Exposure to high intensity sound for a sufficient duration may 
result in behavioral reactions and auditory effects such as a noise-
induced threshold shift--an increase in the auditory threshold after 
exposure to noise (Finneran et al., 2005). Factors that influence the 
amount of threshold shift include the amplitude, duration, frequency 
content, temporal pattern, and energy distribution of noise exposure. 
The magnitude of hearing threshold shift normally decreases over time 
following cessation of the noise exposure. The amount of threshold 
shift just after exposure is the initial threshold shift. If the 
threshold shift eventually returns to zero (i.e., the threshold returns 
to the pre-exposure value), it is a temporary threshold shift (Southall 
et al., 2007).
    When animals exhibit reduced hearing sensitivity (i.e., sounds must 
be louder for an animal to detect them) following exposure to an 
intense sound or sound for long duration, it is referred to as a noise-
induced threshold shift (TS). An animal can experience temporary 
threshold shift (TTS) or permanent threshold shift (PTS). TTS can last 
from minutes or hours to days (i.e., there is complete recovery), can 
occur in specific frequency ranges (i.e., an animal might only have a 
temporary loss of hearing sensitivity between the frequencies of 1 and 
10 kHz), and can be of varying amounts (for example, an animal's 
hearing sensitivity might be reduced initially by only 6 decibel (dB) 
or reduced by 30 dB). PTS is a permanent loss within a specific 
frequency range.
    For cetaceans, published TTS data are limited to the captive 
bottlenose dolphin, beluga, harbor porpoise, and Yangtze finless 
porpoise (Finneran et al., 2000, 2002, 2003, 2005, 2007, 2010a, 2010b; 
Finneran and Schlundt, 2010; Lucke et al., 2009; Mooney et al., 2009a, 
2009b; Popov et al., 2011a, 2011b; Kastelein et al., 2012a; Schlundt et 
al., 2000; Nachtigall et al., 2003, 2004). For pinnipeds in water, data 
are limited to measurements of TTS in harbor seals, an elephant seal, 
and California sea lions (Kastak et al., 1999, 2005; Kastelein et al., 
2012b).
    Marine mammal hearing plays a critical role in communication with 
conspecifics, and interpretation of environmental cues for purposes 
such as predator avoidance and prey capture. Depending on the degree 
(elevation of threshold in dB), duration (i.e., recovery time), and 
frequency range of TTS, and the context in which it is experienced, TTS 
can have effects on marine mammals ranging from discountable to serious 
(similar to those discussed in auditory masking, below). For example, a 
marine mammal may be able to readily compensate for a brief, relatively 
small amount of TTS in a non-critical frequency range that occurs 
during a time where ambient noise is lower and there are not as many 
competing sounds present. Alternatively, a larger amount and longer 
duration of TTS sustained during time when communication is critical 
for successful mother/calf interactions could have more serious 
impacts. Also, depending on the degree and frequency range, the effects 
of PTS on an animal could range in severity, although it is considered 
generally more serious because it is a permanent condition. Of note, 
reduced hearing sensitivity as a simple function of aging has been 
observed in marine mammals, as well as humans and other taxa (Southall 
et al., 2007), so one can infer that strategies exist for coping with 
this condition to some degree, though likely not without cost.
    In addition, chronic exposure to excessive, though not high-
intensity, noise could cause masking at particular frequencies for 
marine mammals that utilize sound for vital biological functions (Clark 
et al., 2009). Acoustic masking occurs when other noises, such as those 
from human sources, interfere with animal detection of acoustic signals 
such as communication calls, echolocation sounds, and environmental 
sounds important to marine mammals. Therefore, under certain 
circumstances, marine mammals whose acoustical sensors or environment 
are being severely masked could also be impaired from maximizing their 
performance fitness in survival and reproduction.
    Masking occurs at the frequency band, which the animals utilize. 
However, lower frequency man-made noises are more likely to affect 
detection of communication calls and other potentially important 
natural sounds such as surf and prey noise. It may also affect 
communication signals when they

[[Page 26021]]

occur near the noise band and thus reduce the communication space of 
animals (e.g., Clark et al., 2009) and cause increased stress levels 
(e.g., Foote et al., 2004; Holt et al., 2009).
    Unlike TS, masking, which can occur over large temporal and spatial 
scales, can potentially affect the species at population, community, or 
even ecosystem levels, as well as individual levels. Masking affects 
both senders and receivers of the signals and could have long-term 
chronic effects on marine mammal species and populations. Recent 
science suggests that low frequency ambient sound levels have increased 
by as much as 20 dB (more than 3 times in terms of sound pressure 
level) in the world's ocean from pre-industrial periods, and most of 
these increases are from distant shipping (Hildebrand 2009). For 
Caltrans' SFOBB construction activities, noises from controlled 
blasting is not likely to contribute to the elevated ambient noise 
levels in the project area in such a way as to increasing potential for 
or severity of masking. Baseline ambient noise levels in the Bay are 
very high due to ongoing shipping, construction and other activities in 
the Bay, and the sound associated with the controlled blasting 
activities will be very brief.
    Finally, exposure of marine mammals to certain sounds could lead to 
behavioral disturbance (Richardson et al., 1995), such as: Changing 
durations of surfacing and dives, number of blows per surfacing, or 
moving direction and/or speed; reduced/increased vocal activities; 
changing/cessation of certain behavioral activities (such as 
socializing or feeding); visible startle response or aggressive 
behavior (such as tail/fluke slapping or jaw clapping); avoidance of 
areas where noise sources are located; and/or flight responses (e.g., 
pinnipeds flushing into water from haul outs or rookeries).
    The onset of behavioral disturbance from anthropogenic noise 
depends on both external factors (characteristics of noise sources and 
their paths) and the receiving animals (hearing, motivation, 
experience, demography) and is also difficult to predict (Southall et 
al., 2007). For impulse noises (such as the controlled implosions 
associated with the dismantling of the original SFOBB spans), NMFS uses 
received levels of 165 dB SEL to predict the onset of behavioral 
harassment for mid-frequency cetaceans and phocid pinnipeds (bottlenose 
dolphins and harbor seals and northern elephant seals, respectively); 
135 dB SEL for high-frequency cetaceans (harbor porpoises); and 183 dB 
SEL for otariid pinnipeds (California sea lions and northern fur 
seals).
    The biological significance of many of these behavioral 
disturbances is difficult to predict, especially if the detected 
disturbances appear minor. However, the consequences of behavioral 
modification could be biologically significant if the change affects 
growth, survival, and/or reproduction, which depends on the severity, 
duration, and context of the effects.
Potential Effects From Controlled Pier Implosion
    It is expected that an intense impulse from the controlled blasting 
of Piers E19 and E20 have the potential to impact marine mammals in the 
vicinity of the activity. The majority of impacts will be startle 
behavioral responses and temporary behavioral modification of marine 
mammals. However, a few individual animals could be exposed to sound 
levels that may cause TTS.
    The underwater explosion will send a shock wave and blast noise 
through the water, release gaseous by-products, create an oscillating 
bubble, and cause a plume of water to shoot up from the water surface. 
The shock wave and blast noise are of most concern to marine animals. 
The effects of an underwater explosion on a marine mammal depends on 
many factors, including the size, type, and depth of both the animal 
and the explosive charge; the depth of the water column; and the 
standoff distance between the charge and the animal, as well as the 
sound propagation properties of the environment. Potential impacts can 
range from brief effects (such as behavioral disturbance), tactile 
perception, physical discomfort, slight injury of the internal organs 
and the auditory system, to death of the animal (Yelverton et al., 
1973; DoN, 2001). Non-lethal injury includes slight injury to internal 
organs and the auditory system; however, delayed lethality can be a 
result of individual or cumulative sublethal injuries (DoN, 2001). 
Immediate lethal injury would be a result of massive combined trauma to 
internal organs as a direct result of proximity to the point of 
detonation (DoN 2001). Generally, the higher the level of impulse and 
pressure level exposure, the more severe the impact to an individual.
    Injuries resulting from a shock wave take place at boundaries 
between tissues of different density. Different velocities are imparted 
to tissues of different densities, and this can lead to their physical 
disruption. Blast effects are greatest at the gas-liquid interface 
(Landsberg 2000). Gas-containing organs, particularly the lungs and 
gastrointestinal (GI) tract, are especially susceptible (Goertner 1982; 
Hill 1978; Yelverton et al., 1973). In addition, gas-containing organs 
including the nasal sacs, larynx, pharynx, trachea, and lungs may be 
damaged by compression/expansion caused by the oscillations of the 
blast gas bubble. Intestinal walls can bruise or rupture, with 
subsequent hemorrhage and escape of gut contents into the body cavity. 
Less severe GI tract injuries include contusions, petechiae (small red 
or purple spots caused by bleeding in the skin), and slight 
hemorrhaging (Yelverton et al., 1973).
    Because the ears are the most sensitive to pressure, they are the 
organs most sensitive to injury (Ketten 2000). Sound-related damage 
associated with blast noise can be theoretically distinct from injury 
from the shock wave, particularly farther from the explosion. If an 
animal is able to hear a noise, at some level it can damage its hearing 
by causing decreased sensitivity (Ketten 1995). Sound-related trauma 
can be lethal or sublethal. Lethal impacts are those that result in 
immediate death or serious debilitation in or near an intense source 
and are not, technically, pure acoustic trauma (Ketten 1995). Sublethal 
impacts include hearing loss, which is caused by exposures to 
perceptible sounds. Severe damage (from the shock wave) to the ears 
includes tympanic membrane rupture, fracture of the ossicles, damage to 
the cochlea, hemorrhage, and cerebrospinal fluid leakage into the 
middle ear. Moderate injury implies partial hearing loss due to 
tympanic membrane rupture and blood in the middle ear. Permanent 
hearing loss also can occur when the hair cells are damaged by one very 
loud event, as well as by prolonged exposure to a loud noise or chronic 
exposure to noise. The level of impact from blasts depends on both an 
animal's location and, at outer zones, on its sensitivity to the 
residual noise (Ketten 1995).
    The above discussion concerning underwater explosions only pertains 
to open water detonations in a free field. Caltrans' demolition of 
Piers E19 and E20 using controlled implosion uses a confined detonation 
method, meaning that the charges will be placed within the structure. 
Therefore, most energy from the explosive shock wave will be absorbed 
through the destruction of the structure itself, and will not propagate 
through the open water. Measurements and modeling from confined 
underwater detonation for structure removal showed that energy from 
shock waves and noise impulses were greatly reduced in the water column 
compared to expected levels from open water detonations (Hempen et al., 
2007;

[[Page 26022]]

Department 2016). Therefore, with monitoring and mitigation measures 
discussed below, Caltrans' controlled implosions of Piers E19 and E20 
are not likely to have injury or mortality effects on marine mammals in 
the project vicinity. Instead, NMFS considers that Caltrans' controlled 
implosions in the San Francisco Bay are most likely to cause behavioral 
harassment and may cause TTS in a few individual of marine mammals, as 
discussed below.
    Changes in marine mammal behavior are expected to result from acute 
stress, or startle, responses. This expectation is based on the idea 
that some sort of physiological trigger must exist to change any 
behavior that is already being performed, and this may occur due to 
being startled by the implosion events. The exception to this 
expectation is the case of behavioral changes due to auditory masking 
(increasing call rates or volumes to counteract increased ambient 
noise). Masking is not likely since the Caltrans' controlled implosion 
will only consist of five to six short, sequential detonations that 
last for approximately 3-4 seconds each.
    The removal of the SFOBB East Span is not likely to negatively 
affect the habitat of marine mammal populations because no permanent 
loss of habitat will occur, and only a minor, temporary modification of 
habitat will occur due to the addition of sound and activity associated 
with the dismantling activities.
    Project activities will not affect any pinniped haul out sites or 
pupping sites. The YBI harbor seal haul out site is on the opposite 
site of the island from the SFOBB Project area. Because of the distance 
and the island blocking the sound, underwater noise and pressure levels 
from the SFOBB Project will not reach the haul out site. Other haul out 
sites for sea lions and harbor seals are at a sufficient distance from 
the SFOBB Project area that they will not be affected. The closest 
recognized harbor seal pupping site is at Castro Rocks, approximately 
8.7 miles (14 kilometers) from the SFOBB Project area. No sea lion 
rookeries are found in the Bay.
    The addition of underwater sound from SFOBB Project activities to 
background noise levels can constitute a potential cumulative impact on 
marine mammals. However, these potential cumulative noise impacts will 
be short in duration and will not occur in biologically important 
areas, will not significantly affect biologically important activities, 
and are not expected to have significant environmental effects, as 
noted in the original FHWA 2001 FEIS for the SFOBB project, 
incorporated by reference into NMFS' 2003 EA and subsequent 
Supplemental EAs (2009 and 2015) for the issuance of IHAs for the SFOBB 
project.
    Marine mammal forage on fish within SFB and pier implosions have 
the potential to injure or kill fish in the immediate area. During 
previous pier implosion and pile driving activities, Caltrans reported 
mortality to prey species of marine mammals, including northern 
anchovies and Pacific herring (Department 2016), averaging 
approximately 200 fish per implosion event (none of which were ESA-
listed species and none of which are managed under a Fishery Management 
Plan). These few isolated fish mortality events are not anticipated to 
have a substantial effect on prey species populations or their 
availability as a food resource for marine mammals.
    Studies on explosives also suggest that larger fish are generally 
less susceptible to death or injury than small fish, and results of 
most studies are dependent upon specific biological, environmental, 
explosive, and data recording factors. For example, elongated forms 
that are round in cross section are less at risk than deep-bodied 
forms; orientation of fish relative to the shock wave may also affect 
the extent of injury; and finally, open water pelagic fish, such as 
those expected to be in the project area, seem to be less affected than 
reef fishes.
    The huge variation in fish populations, including numbers, species, 
sizes, and orientation and range from the detonation point, makes it 
very difficult to accurately predict mortalities at any specific site 
of detonation. Most fish species experience a large number of natural 
mortalities, especially during early life-stages, and any small level 
of mortality caused by the Caltrans' controlled implosion events will 
likely be insignificant to the population as a whole. This negligible 
effect on population levels of forage fish should ensure continued prey 
availability for marine mammal species in the area.
Potential Effects of Pile Driving Activities
    In-water construction activities associated with the project will 
include impact pile driving, vibratory pile driving, and removal. The 
sounds produced by these activities fall into one of two general sound 
types: Pulsed and non-pulsed (defined in the following). The 
distinction between these two sound types is important because they 
have differing potential to cause physical effects, particularly with 
regard to hearing (e.g., Ward 1997 in Southall et al., 2007). Please 
see Southall et al. (2007) for an in-depth discussion of these 
concepts.
    Pulsed sound sources (e.g., explosions, gunshots, sonic booms, 
impact pile driving) produce signals that are brief (typically 
considered to be less than one second), broadband, atonal transients 
(ANSI 1986; Harris 1998; NIOSH 1998; ISO 2003; ANSI 2005) and occur 
either as isolated events or repeated in some succession. Pulsed sounds 
are all characterized by a relatively rapid rise from ambient pressure 
to a maximal pressure value followed by a rapid decay period that may 
include a period of diminishing, oscillating maximal and minimal 
pressures, and generally have an increased capacity to induce physical 
injury as compared with sounds that lack these features.
    Non-pulsed sounds can be tonal, narrowband, or broadband, brief or 
prolonged, and may be either continuous or non-continuous (ANSI 1995; 
NIOSH 1998). Some of these non-pulsed sounds can be transient signals 
of short duration but without the essential properties of pulses (e.g., 
rapid rise time). Examples of non-pulsed sounds include those produced 
by vessels, aircraft, machinery operations such as drilling or 
dredging, vibratory pile driving, and active sonar systems. The 
duration of such sounds, as received at a distance, can be greatly 
extended in a highly reverberant environment.
    Impact hammers operate by repeatedly dropping a heavy piston onto a 
pile to drive the pile into the substrate. Sound generated by impact 
hammers is characterized by rapid rise times and high peak levels, a 
potentially injurious combination (Hastings and Popper 2005). Vibratory 
hammers install piles by vibrating them and allowing the weight of the 
hammer to push them into the sediment. Vibratory hammers produce 
significantly less sound than impact hammers. Peak SPLs may be 180 dB 
or greater, but are generally 10 to 20 dB lower than SPLs generated 
during impact pile driving of the same-sized pile (Oestman et al., 
2009). Rise time is slower, reducing the probability and severity of 
injury, and sound energy is distributed over a greater amount of time 
(Nedwell and Edwards 2002; Carlson et al., 2005).
    The effects of sounds from pile driving might include one or more 
of the following: Temporary or permanent hearing impairment, non-
auditory physical or physiological effects, behavioral disturbance, and 
masking (Richardson et al., 1995; Gordon et al., 2003; Nowacek et al., 
2007; Southall et

[[Page 26023]]

al., 2007). The effects of pile driving or drilling on marine mammals 
are dependent on several factors, including the type and depth of the 
animal; the pile size and type, and the intensity and duration of the 
pile driving or drilling sound; the substrate; the standoff distance 
between the pile and the animal; and the sound propagation properties 
of the environment. Impacts to marine mammals from pile driving are 
expected to result primarily from acoustic pathways. As such, the 
degree of effect is intrinsically related to the frequency, received 
level, and duration of the sound exposure, which are in turn influenced 
by the distance between the animal and the source. The further away 
from the source, the less intense the exposure should be. The substrate 
and depth of the habitat affect the sound propagation properties of the 
environment. In addition, substrates that are soft (e.g., sand) will 
absorb or attenuate the sound more readily than hard substrates (e.g., 
rock), which may reflect the acoustic wave. Soft porous substrates will 
also likely require less time to drive the pile, and possibly less 
forceful equipment, which will ultimately decrease the intensity of the 
acoustic source.
    In the absence of mitigation, impacts to marine species could be 
expected to include physiological and behavioral responses to the 
acoustic signature (Viada et al., 2008). Potential effects from 
impulsive sound sources like pile driving can range in severity from 
effects such as behavioral disturbance to temporary or permanent 
hearing impairment (Yelverton et al., 1973). Due to the nature of the 
pile driving sounds in the project, behavioral disturbance is the most 
likely effect from the activity. Marine mammals exposed to high 
intensity sound repeatedly or for prolonged periods can experience 
hearing threshold shifts. PTS constitutes injury, but TTS does not 
(Southall et al., 2007). Based on the best scientific information 
available, the SPLs for the construction activities in this project are 
below the thresholds that could cause TTS or the onset of PTS.
    Responses to continuous sound, such as vibratory pile installation, 
have not been documented as well as responses to pulsed sounds. With 
both types of pile driving, it is likely that the onset of pile driving 
could result in temporary, short-term changes in an animal's typical 
behavior and/or avoidance of the affected area. These behavioral 
changes may include (Richardson et al., 1995): Changing durations of 
surfacing and dives, number of blows per surfacing, or moving direction 
and/or speed; reduced/increased vocal activities; changing/cessation of 
certain behavioral activities (such as socializing or feeding); visible 
startle response or aggressive behavior (such as tail/fluke slapping or 
jaw clapping); avoidance of areas where sound sources are located; and/
or flight responses (e.g., pinnipeds flushing into water from haulouts 
or rookeries). Pinnipeds may increase their haul-out time, possibly to 
avoid in-water disturbance (Thorson and Reyff 2006). If a marine mammal 
responds to a stimulus by changing its behavior (e.g., through 
relatively minor changes in locomotion direction/speed or vocalization 
behavior), the response may or may not constitute taking at the 
individual level, and is unlikely to affect the stock or the species as 
a whole. However, if a sound source displaces marine mammals from an 
important feeding or breeding area for a prolonged period, impacts on 
animals, and if so potentially on the stock or species, could 
potentially be significant (e.g., Lusseau and Bejder 2007; Weilgart 
2007).
    The biological significance of many of these behavioral 
disturbances is difficult to predict, especially if the detected 
disturbances appear minor. However, the consequences of behavioral 
modification could be biologically significant if the change affects 
growth, survival, or reproduction. Significant behavioral modifications 
that could potentially lead to effects on growth, survival, or 
reproduction include:
     Drastic changes in diving/surfacing patterns (such as 
those thought to cause beaked whale stranding due to exposure to 
military mid-frequency tactical sonar);
     Longer-term habitat abandonment due to loss of desirable 
acoustic environment; and
     Longer-term cessation of feeding or social interaction.
    The onset of behavioral disturbance from anthropogenic sound 
depends on both external factors (characteristics of sound sources and 
their paths) and the specific characteristics of the receiving animals 
(hearing, motivation, experience, demography) and is difficult to 
predict (Southall et al., 2007).
    Non-Auditory Physiological Effects--Non-auditory physiological 
effects or injuries that theoretically might occur in marine mammals 
exposed to strong underwater sound include stress, neurological 
effects, bubble formation, resonance effects, and other types of organ 
or tissue damage (Cox et al., 2006; Southall et al., 2007). Studies 
examining such effects are limited. In general, little is known about 
the potential for pile driving or removal to cause auditory impairment 
or other physical effects in marine mammals. Available data suggest 
that such effects, if they occur at all, will presumably be limited to 
short distances from the sound source and to activities that extend 
over a prolonged period. The available data do not allow identification 
of a specific exposure level above which non-auditory effects can be 
expected (Southall et al., 2007) or any meaningful quantitative 
predictions of the numbers (if any) of marine mammals that might be 
affected in those ways. Marine mammals that show behavioral avoidance 
of pile driving, including some odontocetes and some pinnipeds, are 
especially unlikely to incur auditory impairment or non-auditory 
physical effects.
    Auditory Masking--Natural and artificial sounds can disrupt 
behavior by masking. The frequency range of the potentially masking 
sound is important in determining any potential behavioral impacts. 
Because sound generated from in-water pile driving and removal is 
mostly concentrated at low-frequency ranges, it may have less effect on 
high frequency echolocation sounds made by porpoises. Given that the 
energy distribution of pile driving covers a broad frequency spectrum, 
sound from these sources will likely be within the audible range of 
marine mammals present in the project area. Impact pile driving 
activity is relatively short-term, with rapid pulses occurring for 
approximately fifteen minutes per pile. The probability for impact pile 
driving resulting from this action masking acoustic signals important 
to the behavior and survival of marine mammal species is low. Vibratory 
pile driving is also relatively short-term, with rapid oscillations 
occurring for approximately one and a half hours per pile. It is 
possible that vibratory pile driving resulting from this action may 
mask acoustic signals important to the behavior and survival of marine 
mammal species, but the short-term duration and limited affected area 
will result in insignificant impacts from masking. Any masking event 
that could possibly rise to Level B harassment under the MMPA will 
occur concurrently within the zones of behavioral harassment already 
estimated for vibratory and impact pile driving, and which have already 
been taken into account in the exposure analysis.

Estimated Take

    This section provides an estimate of the number of incidental takes 
for authorization through this IHA, which will inform both NMFS' 
consideration

[[Page 26024]]

of ``small numbers'' and the negligible impact determination.
    Harassment is the only type of take expected to result from these 
activities. Except with respect to certain activities not pertinent 
here, section 3(18) of the MMPA defines ``harassment'' as any act of 
pursuit, torment, or annoyance which (i) has the potential to injure a 
marine mammal or marine mammal stock in the wild (Level A harassment); 
or (ii) has the potential to disturb a marine mammal or marine mammal 
stock in the wild by causing disruption of behavioral patterns, 
including, but not limited to, migration, breathing, nursing, breeding, 
feeding, or sheltering (Level B harassment).
    Authorized takes will be by Level B harassment only, in the form of 
disruption of behavioral patterns and TTS, for individual marine 
mammals resulting from exposure to pile driving and controlled 
blasting. Based on the nature of the activity and the anticipated 
effectiveness of the mitigation measures such as the use of a blast 
attenuation system and shutdown zones, Level A harassment is neither 
anticipated nor authorized for blasting. Although Caltrans has not 
requested Level A harassment for their construction activities in the 
past, in consultation with the Marine Mammal Commission, Caltrans has 
requested Level A take of 120 harbor seals and 2 elephant seals during 
pile driving activities.
    As described previously, no mortality is anticipated or authorized 
for this activity. Below we describe how the take is estimated.
    Described in the most basic way, we estimate take by considering: 
(1) Acoustic thresholds above which NMFS believes the best available 
science indicates marine mammals will be behaviorally harassed or incur 
some degree of permanent hearing impairment; (2) the area or volume of 
water that will be ensonified above these levels in a day; (3) the 
density or occurrence of marine mammals within these ensonified areas; 
and, (4) and the number of days of activities. Below, we describe these 
components in more detail and present the take estimate.

Acoustic Thresholds

    Using the best available science, NMFS has developed acoustic 
thresholds that identify the received level of underwater sound above 
which exposed marine mammals will be reasonably expected to be 
behaviorally harassed (equated to Level B harassment) or to incur PTS 
of some degree (equated to Level A harassment). Thresholds have also 
been developed to identify the pressure levels above which animals may 
incur different types of tissue damage from exposure to pressure waves 
from explosive detonation.
    Level B harassment for non-explosive sources--Though significantly 
driven by received level, the onset of behavioral disturbance from 
anthropogenic noise exposure is also informed to varying degrees by 
other factors related to the source (e.g., frequency, predictability, 
duty cycle), the environment (e.g., bathymetry), and the receiving 
animals (hearing, motivation, experience, demography, behavioral 
context) and can be difficult to predict (Southall et al., 2007, 
Ellison et al., 2011). Based on what the available science indicates 
and the practical need to use a threshold based on a factor that is 
both predictable and measurable for most activities, NMFS uses a 
generalized acoustic threshold based on received level to estimate the 
onset of behavioral harassment. NMFS predicts that marine mammals are 
likely to be behaviorally harassed in a manner we consider Level B 
harassment when exposed to underwater anthropogenic noise above 
received levels of 120 dB re 1 [mu]Pa (rms) for continuous (e.g. 
vibratory pile-driving, drilling) and above 160 dB re 1 [mu]Pa (rms) 
for non-explosive impulsive (e.g., seismic airguns) or intermittent 
(e.g., scientific sonar) sources.
    Caltrans's activity includes the use of continuous (vibratory pile 
driving) and impulsive (impact pile driving) sources, and therefore the 
120 and 160 dB re 1 [mu]Pa (rms) thresholds are applicable.
    Level A harassment for non-explosive sources--NMFS' Technical 
Guidance for Assessing the Effects of Anthropogenic Sound on Marine 
Mammal Hearing (Technical Guidance, 2016) identifies dual criteria to 
assess auditory injury (Level A harassment) to five different marine 
mammal groups (based on hearing sensitivity) as a result of exposure to 
noise from two different types of sources (impulsive or non-impulsive). 
Caltrans' activity includes the use of impulsive (impact driving) AND 
non-impulsive (vibratory driving) sources.
    These thresholds are provided in the table below. The references, 
analysis, and methodology used in the development of the thresholds are 
described in NMFS 2016 Technical Guidance, which may be accessed at: 
http://www.nmfs.noaa.gov/pr/acoustics/guidelines.htm.
    Explosive sources--Based on the best available science, NMFS uses 
the acoustic and pressure thresholds indicated in Table 2 to predict 
the onset of behavioral harassment, PTS, tissue damage, and mortality.
    Based on the best available scientific data, NMFS' 2016 Technical 
Guidance for Assessing the Effects of Anthropogenic Sound on Marine 
Mammal Hearing includes acoustic thresholds related to PTS and TTS for 
impulsive sounds that are expressed as weighted, cumulative sound 
exposure levels (SELcum) and unweighted peak sound pressure levels 
(SPLPK), as presented in Table 3.

                                       Table 2--NMFS Take Thresholds for Marine Mammals From Underwater Implosions
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          Level B harassment              Level A               Serious injury
                                                  ----------------------------------    harassment    ---------------------------------
             Group                   Species                                        ------------------    Gastro-                           Mortality
                                                     Behavioral           TTS                            intestinal         Lung
                                                                                            PTS            tract
--------------------------------------------------------------------------------------------------------------------------------------------------------
Mid-freq cetacean.............  Bottlenose         165 dB SEL....  170 dB SEL or     185 dB SEL or     237 dB SPL...  39.1M1/3 (1+[D/   91.4M\1/3\ (1+[D/
                                 dolphin.                           224 dB SPLpk.     230 dB SPLpk.                    10.081])1/2 Pa-   10.081])\1/2\
                                                                                                                       sec.              Pa-sec.
                                                                                                                      where: M = mass   where: M = mass
                                                                                                                       of the animals    of the animals
                                                                                                                       in kg,.           in kg,
                                                                                                                      D = depth of      D = depth of
                                                                                                                       animal in m.      animal in m.
High-freq cetacean............  Harbor porpoise..  135 dB SEL....  140 dB SEL or     155 dB SEL or
                                                                    196 dB SPLpk.     202 dB SPLpk.
Phocidae......................  Harbor seal &      165 dB SEL....  170 dB SEL or     185 dB SEL or
                                 northern                           212 dB SPLpk.     218 dB SPLpk.
                                 elephant seal.
Otariidae.....................  California sea     183 dB SEL....  188 dB SEL or     203 dB SEL or
                                 lion & northern                    226 dBpk.         232 dB SPLpk.
                                 fur seal.
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Note: All dB values are referenced to 1 [micro]Pa. SPLpk = Peak sound pressure level; psi = pounds per square inch.


[[Page 26025]]


             Table 3--Thresholds Identifying the Onset of Permanent Threshold Shift for Pile Driving
----------------------------------------------------------------------------------------------------------------
                                                     PTS onset acoustic thresholds * (Received level)
              Hearing Group              -----------------------------------------------------------------------
                                                   Impulsive                         Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans............  Cell 1: Lpk,flat: 219 dB;    Cell 2: LE,LF,24h: 199 dB.
                                           LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans............  Cell 3: Lpk,flat: 230 dB;    Cell 4: LE,MF,24h: 198 dB.
                                           LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans...........  Cell 5: Lpk,flat: 202 dB;    Cell 6: LE,HF,24h: 173 dB.
                                           LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater)......  Cell 7: Lpk,flat: 218 dB;    Cell 8: LE,PW,24h: 201 dB.
                                           LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater).....  Cell 9: Lpk,flat: 232 dB;    Cell 10: LE,OW,24h: 219 dB.
                                           LE,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for
  calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level
  thresholds associated with impulsive sounds, these thresholds should also be considered.
Note: Peak sound pressure (Lpk) has a reference value of 1[mu]Pa, and cumulative sound exposure level (LE) has a
  reference value of 1 [mu]Pa\2\s. In this Table, thresholds are abbreviated to reflect American National
  Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI as incorporating
  frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript ``flat'' is
  being included to indicate peak sound pressure should be flat weighted or unweighted within the generalized
  hearing range. The subscript associated with cumulative sound exposure level thresholds indicates the
  designated marine mammal auditory weighted function (LF, MF, and HF cetaceans, and PW and OW pinnipeds) and
  that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds could be
  exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible, it
  is valuable for action proponents to indicate the conditions under which these acoustic thresholds will be
  exceeded.

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that will feed into identifying the area ensonified above the 
acoustic thresholds.
    For pier removal activities, hydroacoustic monitoring was performed 
during the implosions of Piers E3 through E18. Results for this 
monitoring were used to determine distances to marine mammal threshold 
criteria for underwater blasting. The criterion for lung injury and 
mortality to marine mammals is dependent on the mass of the animal and 
the depth of the animal in the water column; animals smaller in mass 
are more susceptible to injury from impulse pressures. The criterion is 
an impulse metric, expressed in pascal-second or psi-msec (Table 4). 
The estimated mass of a juvenile fur seal (15 kilograms (33 pounds)), 
was used in the lung injury and mortality calculations, because this 
will be the smallest animal potentially to be exposed to the 
implosions. The depth at which the animal is exposed also affects the 
criterion threshold calculation. The water depth around Piers E19 and 
E20 is very shallow, at 3 to 4 meters (10 to 12 feet). Although 
implosions will take place in shallow areas, marine mammals are more 
likely to be present in slightly deeper waters. Therefore, an average 
depth for the project area of 6 meters (20 feet) was used in the 
threshold calculation.
    Caltrans will use hydroacoustic monitoring results from the 
implosions of Piers E3 through E18 to estimate distances to marine 
mammal thresholds for the implosion of Piers E19 and E20 (Department 
2015a, 2016). Measured distances from the implosion of Piers E17 to E18 
(two-pier implosion event) were used to estimate distances to threshold 
criteria for the implosion of Piers E19 and E20. The measured distances 
to threshold criteria from the previous Pier E17 and E18 implosion 
event are shown in Tables 5 and 6. Depictions of the isopleths for all 
functional hearing groups is found in Figures 9-13 in the application.

   Table 4--Measured Distances to Underwater Blasting Threshold Criteria for Level B Behavioral and TTS and Level A PTS From the Previous Implosion of
    Piers E17 and E18 in a Single Event and Estimated Distances to These Threshold Criteria for the Implosion of Piers E19 and E20 in a Single Event
 
 
--------------------------------------------------------------------------------------------------------------------------------------------------------
Species hearing group               .....................         Behavioral            TTS \1\ (meters)
                                                                    (meters)
                                                PTS \1\ (meters)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Mid-Frequency Cetaceans (Dolphins)        Threshold          165 dB SELcum       224 dB Peak       170 dB SELcum       230 dB Peak       185 dB SELcum
                                   ---------------------------------------------------------------------------------------------------------------------
                                    Piers E17-E18                     155.75              40.84             109.42              27.13               37.8
                                     Measured.                           200                 50                120                 30                 40
                                    Piers E19-E20
                                     Estimate.
--------------------------------------------------------------------------------------------------------------------------------------------------------
High-Frequency Cetaceans                  Threshold          135 dB SELcum       196 dB Peak       140 dB SELcum       202 dB Peak       155 dB SELcum
 (Porpoises).
                                   ---------------------------------------------------------------------------------------------------------------------
                                    Piers E17-E18                     1142.1              279.2             802.54             185.01             278.28
                                     Measured.                         1,220                290                830                200                290
                                    Piers E19-E20
                                     Estimate.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Phocid Pinnipeds (Seals)..........        Threshold          165 dB SELcum       212 dB Peak       170 dB SELcum       218 dB Peak       185 dB SELcum
                                   ---------------------------------------------------------------------------------------------------------------------
                                    Piers E17-E18                     278.59              92.96             195.38              61.57              67.36
                                     Measured.                           290                100                200                 70                 70
                                    Piers E19-E20
                                     Estimate.
--------------------------------------------------------------------------------------------------------------------------------------------------------


[[Page 26026]]


   Table 4--Measured Distances to Underwater Blasting Threshold Criteria for Level B Behavioral and TTS and Level A PTS From the Previous Implosion of
   Piers E17 and E18 in a Single Event and Estimated Distances to These Threshold Criteria for the Implosion of Piers E19 and E20 in a Single Event--
                                                                        Continued
 
 
--------------------------------------------------------------------------------------------------------------------------------------------------------
Species hearing group               .....................         Behavioral            TTS \1\ (meters)
                                                                    (meters)
                                                PTS \1\ (meters)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Otariid Pinnipeds (Sea Lions).....        Threshold          183 dB SELcum       226 dB Peak       188 dB SELcum       232 dB Peak       203 dB SELcum
                                   ---------------------------------------------------------------------------------------------------------------------
                                    Piers E17-E18                       75.9  .................              53.04              23.47              18.29
                                     Measured.                            80              35.66                 60                 30                 20
                                    Piers E19-E20                                            40
                                     Estimate.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
 1. For the TTS and PTS criteria thresholds with dual criteria, the largest criteria distances (i.e., more conservative) are shown in bold.
Threshold Source: NMFS 2016.
Isopleth Distance Sources: Estimated distances to threshold criteria for the implosion of two small piers were determined based on measured distance to
  threshold criteria from the implosion of Piers E17 and E18.


 Table 5--Estimated Distances to Underwater Blasting Threshold Criteria for Level A GI Tract and Lung Injury and
                    Mortality for Implosion of Pier E3, Two Small Piers and Four Small Piers
 
 
----------------------------------------------------------------------------------------------------------------
Species                         .................      GI tract (meters)     Lung \1\ (meters)  Mortality \1\
                                                                                                 (meters)
----------------------------------------------------------------------------------------------------------------
All Species...................      Threshold      237 dB Peak    104 psi    39.1 (15 kg)\1/3\   91.4 (15 kg)\1/
                                                                              (1+[6/10.081])\1/     3\ (1+[6/
                                                                               2\ = 122 Pa-sec   10.081])\1/2\ =
                                                                                                    285 Pa-sec
                               ---------------------------------------------------------------------------------
                                Piers E17-E18               17           17  <12..............  <12
                                 Measured.
                                Pier Implosion              27           27  <12..............  <12
                                 Estimate.
----------------------------------------------------------------------------------------------------------------
Notes:
Lung injury and mortality threshold calculations are for a 15-kilogram (33-pound) juvenile fur seal, the
  smallest marine mammal with the potential to be present in the project area.
Threshold Source: Finneran and Jenkins 2012.
Isopleth Distance Sources: Estimated distances to threshold criteria for the implosion of piers were determined
  based on measured distance to threshold criteria from the implosions of Pier E4, Piers E17 to E18, Piers E11
  to E13 and Piers E14 to E16.

    For pile driving, the distance to the marine mammal threshold 
criteria for vibratory and impact driving were calculated based on 
hydroacoustic measurements collected during previous pile-driving 
activities for the SFOBB Project and other projects, involving similar 
activities under similar conditions. Measured sound pressure levels 
from other projects came from Caltrans' Compendium of Pile Driving 
Sound Data (Department 2007), which provides information on sound 
pressures resulting from pile driving measured throughout Northern 
California. Sound exposure levels for 36 inch concrete piles were 
derived from the Mukilteo Ferry Test Pile Project. Distances to marine 
mammal threshold criteria were calculated for all pile types and 
installation methods listed above. These distances were calculated 
using the NMFS-provided companion User Spreadsheet.

                          Table 6--NMFS User Spreadsheet Input Values for Pile Driving
 
 
----------------------------------------------------------------------------------------------------------------
                                          H-Pile (vibratory)         24 inch steel            36 inch steel
                                                                       (vibratory)              (vibratory)
----------------------------------------------------------------------------------------------------------------
Vibratory Driving of Steel Piles:
    Spreadsheet Tab Used.............  (A) Non-Impulsive, Cont  (A) Non-Impulsive, Cont  (A) Non-Impulsive,
                                                                                          Cont.
    Source Level (RMS SPL)...........  150....................  165....................  170.
    Weighting Factor Adjustment (kHz)  2.5....................  2.5....................  2.5.
    (a) Activity Duration (h) within   0.5....................  1......................  1.333333.
     24-h period.
    Propagation (xLogR)..............  15.....................  15.....................  15.
    Distance of source level (meters)  10.....................  10.....................  10.
     *.
    Other factors....................
----------------------------------------------------------------------------------------------------------------
                                           H-Pile (impact)       24 inch steel (impact)   36 inch steel (impact)
----------------------------------------------------------------------------------------------------------------
Impact Driving of Steel Piles:
    Spreadsheet Tab Used.............  (E.1) Impact pile        (E.1) Impact pile        (E.1) Impact pile
                                        driving.                 driving.                 driving.
    Source Level (Single Strike/shot   160....................  170 *..................  173 *.
     SEL).
    Weighting Factor Adjustment (kHz)  2......................  2......................  2
    (a) Number of strikes in 1 h.....  200....................  450....................  600
    (a) Activity Duration (h) within   6......................  4......................  4
     24-h period.
    Propagation (xLogR)..............  15.....................  15.....................  15
    Distance of source level (meters)  10.....................  10.....................  10
     *.
    Other factors....................  .......................  Using Bubble Curtain *.  Using Bubble Curtain *.

[[Page 26027]]

 
Pile Proofing (Impact):
    Spreadsheet Tab Used.............  (E.1) Impact pile        (E.1) Impact pile        (E.1) Impact pile
                                        driving.                 driving.                 driving.
    Source Level (Single Strike/shot   160....................  177....................  180.
     SEL).
    Weighting Factor Adjustment (kHz)  2......................  2......................  2.
    (a) Number of strikes in 1 h.....  20.....................  20.....................  20.
    (a) Activity Duration (h) within   2......................  2......................  2.
     24-h period.
    Propagation (xLogR)..............  15.....................  15.....................  15.
    Distance of source level (meters)  10.....................  10.....................  10.
     *.
    Other factors....................
----------------------------------------------------------------------------------------------------------------
* Attenuated value--Bubble curtain is assumed to provide 7dB reduction.

    For calculation of SELcum threshold distances, the following 
assumptions were made:
     Only one type/size of pile will be installed on the same 
day;
     One type of hammer to be used at a given time;
     Only one pile installation method, impact or vibratory, 
will be performed on the same day;
     A maximum of four steel pipe piles will be installed 
(impact driving or vibratory) on the same day;
     A maximum of six H-piles will be installed (impact or 
vibratory) on the same day; and
     A maximum of two pile will be proof-tested with an impact 
hammer on the same day; administering a maximum of 20 strikes per pile.
    The distances to the marine mammal threshold criteria for these 
pile driving and pile removal activities are shown in Table 7.

                                    Table 7--Distances to Levels A and B Harassment Threshold Criteria for Impact and Vibratory Pile Driving and Pile Removal
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                         Parameters                                               Level B ZOI radii (meters)                       Level A ZOI radii  (meters)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                     Low-         Mid-        High-
        Pile size and type               Drive method       Piles per    Attenuation system    160 dB RMS       120 dB RMS        frequency    frequency    frequency      Phocid      Otariid
                                                               day                                                                cetaceans    cetaceans    cetaceans    pinnipeds    pinnipeds
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
H-Pile............................  Vibratory............            6  None................           NA  1,000...............            1            1            2            1            1
24 inch steel.....................  Vibratory............            4  None................           NA  Calculated 10,000...           13            1           19            8            1
                                                                                                           Practical 2,000.....
36 inch steel.....................  Vibratory............            4  None................           NA  Calculated 21,544...           33            3           49           20            1
                                                                                                           Practical 2,000.....
H-Pile............................  Impact...............            6  None................          100  NA..................           33            1           39           18            1
24 inch steel.....................  Impact...............            4  Bubble Curtain......          215  NA..................          201            7          239          107            8
36 inch steel.....................  Impact...............            4  Bubble Curtain......          541  NA..................          386           14          459          206           15
H-Pile............................  Proof Testing........            2  None................          100  NA..................            3            0            4            2            0
24 inch steel.....................  Proof Testing........            2  None................        1,000  NA..................           46            2           55           25            2
36 inch steel.....................  Proof Testing........            2  None................        2,512  NA..................           74            3           88           39            3
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Sources: Sound levels from the Department's Compendium of Pile Driving Sound Data (Department 2007). Distances were calculated using the NMFS-provided companion User Spreadsheet, available at
  http://www.nmfs.noaa.gov/pr/acoustics/guidelines.htm.

    The distance to the 120 dB rms Level B Zone of Influence (ZOI) 
threshold for vibratory pile driving was calculated to be 10,000 meters 
for 24-inch (0.61-meter) diameter steel pipe piles and 21,544 meters 
for 36-inch (0.91-meter) diameter steel pipe piles. Previous monitoring 
for the SFOBB Project has shown background sound levels in the active 
portions of the Bay, near the project area, to range from 110 to 140 dB 
rms, with typical background levels in the range of 110 to 120 dB rms 
(Department 2015). During previous hydroacoustic monitoring for the 
SFOBB Project, it has not been possible to detect or distinguish sound 
from vibratory pile driving beyond 1,000 to 2,000 meters (3,280 to 
6,562 feet) from the source (Rodkin 2009). Under all previous IHAs for 
the SFOBB Project, which included vibratory pile driving, the ZOI for 
this activity has been set at 2,000 meters (6,562 feet) or less (NOAA 
2016). Furthermore, it unlikely that marine mammals in the Bay will 
detect or show response to this sound at distances greater than 2,000 
meters (6,562 feet), because of the background sound levels in the 
Central Bay. Therefore, the practical, applied ZOI for the vibratory 
driving of 24-inch (0.61-meter) and 36-inch (0.91-meter) diameter steel 
pipe piles has been set at 2,000 meters (6,562 feet), as shown in Table 
6.
    When NMFS Technical Guidance (2016) was published, in recognition 
of the fact that ensonified area/volume could be more technically 
challenging to predict because of the duration component in the new 
thresholds, we developed a User Spreadsheet that includes tools to help 
predict a simple isopleth that can be used in conjunction with marine 
mammal density or occurrence to help predict takes. We note that 
because of some of the assumptions included in the methods used for 
these tools, we anticipate that isopleths produced are typically going 
to be overestimates of some degree, which will result in some degree of 
overestimate of Level A take. However, these tools offer the best way 
to predict appropriate isopleths when more sophisticated 3D modeling 
methods are not available, and NMFS continues to develop ways to 
quantitatively refine these tools, and will qualitatively address the 
output where appropriate. For stationary sources pile driving, NMFS 
User Spreadsheet predicts the closest distance at which, if a marine 
mammal remained at that distance the whole duration of the activity, it 
will not incur PTS. Inputs used in the User Spreadsheet, and the 
resulting isopleths are reported below in Table 7.

Marine Mammal Occurrence

    In this section we provide the information about the presence, 
density, or group dynamics of marine mammals that will inform the take 
calculations.

[[Page 26028]]

    No systematic line transect surveys of marine mammals have been 
performed in the Bay. Therefore, the in-water densities of harbor 
seals, California sea lions, and harbor porpoises were calculated based 
on 17 years of observations during monitoring for the SFOBB 
construction and demolition. Care was taken to eliminate multiple 
observations of the same animal, although this can be difficult and is 
likely that the same individual may have been counted multiple times on 
the same day. The amount of monitoring performed per year varied, 
depending on the frequency and duration of construction activities with 
the potential to affect marine mammals. During the 257 days of 
monitoring from 2000 through 2017 (including 15 days of baseline 
monitoring in 2003), 1,029 harbor seals, 83 California sea lions, and 
24 harbor porpoises were observed in waters in the project vicinity in 
total. In 2015, 2016, and 2017, the number of harbor seals in the 
project area increased significantly. In 2017, the number of harbor 
porpoise in the project area also increased significantly. Therefore, a 
harbor seal density estimate was calculated for 2015-2017, and a harbor 
porpoise density estimate was calculated for 2017, which may better 
reflect the current use of the project area by these animals. These 
observations included data from baseline, pre-, during, and post-pile 
driving, mechanical dismantling, on-shore blasting, and off-shore 
implosion activities.
    Insufficient sighting data exist to estimate the density of 
bottlenose dolphins. However, a single bottlenose dolphin has been 
observed regularly, south of the SFOBB east span since fall 2016. 
During monitoring performed in 2017 for the SFOBB, two bottlenose 
dolphins were observed south of the SFOBB.
    Insufficient sighting data exist to estimate elephant seal 
densities in the Bay. Generally, only juvenile elephant seals enter the 
Bay and do not remain long. The most recent sighting near the project 
area was in 2012, on the beach at Clipper Cove on Treasure Island, when 
a healthy yearling elephant seal hauled out for approximately 1 day. 
Approximately 100 juvenile northern elephant seals strand in or near 
the Bay each year, including individual strandings at YBI and Treasure 
Island (less than 10 strandings per year).
    Insufficient sighting data exist to estimate northern fur seal 
densities in the Bay. Only two to four northern fur seals strand in the 
Bay each year, and they are unlikely to occur in the project area.
    The size of the areas monitored for marine mammals has increased 
over the 17 years of observations. The majority of pinniped monitoring 
has been focused within a 610-meter (2,000-foot) radius of the work 
area. Although some pinniped observations have been recorded at greater 
distances, in part because of recent monitoring of larger areas for 
harbor porpoise zones during pier implosion, a 2-square-kilometer area, 
corresponding with a 610-meter (2,000-foot) radial distance, was used 
for density calculations. Harbor porpoise sightings in the Bay have 
increased in recent years; however, the majority of harbor porpoise 
observations made during monitoring for the SFOBB Project have been at 
distances ranging from 2,438 to 3,048 meters (8,000 to 10,000 feet) 
from the work area. Therefore, harbor porpoise densities were 
calculated based on a 15-square-kilometer area, corresponding with a 
2,438-meter (8,000-foot) radial distance, with land areas subtracted 
from the area. Numbers used for density calculations are shown in Table 
8. In the cases where densities were refined to capture a narrower 
range of years to be conservative, bold densities were used for take 
calculations.

                   Table 8--Estimated In-Water Density of Marine Mammal Species in SFOBB Area
----------------------------------------------------------------------------------------------------------------
                                            Area of
                                          monitoring        Days of        Number of     Density animals/square
           Species observed              zone (square     monitoring        animals             kilometer
                                          kilometer)                       observed
----------------------------------------------------------------------------------------------------------------
Harbor Seals..........................               2             257            1029  2.002.
2000-2017.............................
Harbor Seals..........................               2              47             372  3.957.
2015-2017.............................
California Sea Lions..................               2             257              83  0.161.
2000-2017.............................
Bottlenose Dolphins 2017..............               2               6               2  Insufficient sighting
                                                                                         data exists to estimate
                                                                                         density.
Harbor Porpoise.......................               3             257              24  0.031.
2000-2017.............................
Harbor Porpoise.......................              15               6              15  0.167.
2017..................................
Elephant Seal.........................               2             257               0  Insufficient sighting
2000-2017.............................                                                   data exists to estimate
                                                                                         density.
Northern Fur Seal.....................               2             257               0  Insufficient sighting
2000-2017.............................                                                   data exists to estimate
                                                                                         density.
Gray Whale............................               2             257               0  Insufficient sighting
2000-2017.............................                                                   data exists to estimate
                                                                                         density.
----------------------------------------------------------------------------------------------------------------
Notes:
Densities for Pacific harbor seals, California sea lions, and harbor porpoises are based on monitoring for the
  east span of the SFOBB from 2000 to 2017.
A second set of Pacific harbor seal densities were calculated from the increase in sightings recorded from 2015
  to 2017.
A second set of harbor porpoise densities were calculated for the increase in sightings that were recorded in
  2017.
Bold densities were used for take calculations.
Sources: Department 2001, 2004b, 2013b, 2013c, 2014, 2015b, 2016, 2017; Perlman 2017.

    For species without enough sightings to construct a density 
estimate, Caltrans uses information based on group size and frequency 
of sightings from previous years of work to inform the number of 
animals estimated to be taken, which is detailed in the Take Estimation 
section below.

[[Page 26029]]

Take Calculation and Estimation

    Here we describe how the information provided above is brought 
together to produce a quantitative take estimate.
Take From Pier Implosion
    The numbers of harbor seals, sea lions and harbor porpoise that may 
be taken by implosion of Piers E19 and E20 were calculated based on 
distances to the marine mammal threshold criteria, duration of the 
activity, and the estimated density of these species in the ZOI.
    The numbers of elephant seals, northern fur seals and bottlenose 
dolphin that may be taken by implosion of Piers E19 and E20 were 
determined based on distances to the marine mammal threshold criteria, 
duration of the activity, and sightings and occurrence of these species 
in the Bay, specifically near the project area. Distances to marine 
mammal threshold criteria were calculated based on the highest sound 
pressure levels generated during the previous pier implosion of Piers 
E17 and E18 (two-pier implosion event). Gray whales were not considered 
for pier implosion activities as those activities will occur in late 
fall and early winter, when gray whales are not found in the Bay area.
    The number of exposures of each species was calculated over the 
entire area of each Level A, Level B, and mortality threshold criteria 
zone for the pier implosion event (Tables 9 through 12).

                                        Table 9--Level A PTS Take Calculations for Implosion of Piers E19 and E20
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                              Species
                                              density         Species                       Level A PTS                      Number of
                 Species                     (animals/        density       Level A ZOI      ZOI Area       Level A PTS      implosion     Level B take
                                              square         (animals/    radii (meters)      (square          take           events        calculated
                                            kilometer)    square meters)                      meters)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Harbor Seal.............................           3.957        3.96E-06              70      29,462.347          0.1166               1          0.1166
Sea Lion................................           0.161        1.61E-07              30       9,118.458          0.0015               1          0.0015
Harbor Porpoise.........................           0.167        1.67E-07             290     315,798.484          0.0527               1          0.0527
Bottlenose Dolphin......................              NA              NA              40       5,026.548              NA               1              NA
Elephant Seal...........................              NA              NA              70      15,393.804              NA               1              NA
Fur Seal................................              NA              NA              30        2,827.43              NA               1              NA
--------------------------------------------------------------------------------------------------------------------------------------------------------


                                       Table 10--Level B TTS Take Calculations for Implosion of Piers E19 and E20
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                              Species
                                              density         Species                       Level B TTS                   Number of pier
                 Species                     (animals/        density       Level B ZOI      ZOI area       Level B TTS      implosion     Level B take
                                              square         (animals/    radii (meters)      (square          Take           events        calculated
                                            kilometer)    square meters)                    kilometers)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Harbor Seal.............................           3.957        3.96E-06             200            0.17          0.6528               1          0.6528
Sea Lion................................           0.161        1.61E-07              60           0.023          0.0038               1          0.0038
Harbor Porpoise.........................           0.167        1.67E-07             830            2.09          0.3483               1          0.3483
Bottlenose Dolphin......................              NA              NA             120           0.045              NA               1              NA
Elephant Seal...........................              NA              NA             200            0.13              NA               1              NA
Fur Seal................................              NA              NA              60           0.011              NA               1              NA
--------------------------------------------------------------------------------------------------------------------------------------------------------


                                    Table 11--Level B Behavioral Take Calculations for Implosion of Piers E19 and E20
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                              Species         Species
                                              density         density                         Level B         Level B     Number of pier
                 Species                     (animals/       (animals/      Level B ZOI   behavioral ZOI    behavioral       implosion     Level B take
                                              square          square      radii (meters)   area  (square       take           events        calculated
                                            kilometer)        meters)                       kilometers)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Harbor Seal.............................           3.957        3.96E-06             290            0.32          1.2496               1          1.2496
Sea Lion................................           0.161        1.61E-07              80           0.036          0.0058               1          0.0058
Harbor Porpoise.........................           0.167        1.67E-07           1,220            4.26          0.7109               1          0.7109
Bottlenose Dolphin......................              NA              NA             200            0.13              NA               1              NA
Elephant Seal...........................              NA              NA             290            0.26              NA               1              NA
Fur Seal................................              NA              NA              80            0.02              NA               1              NA
--------------------------------------------------------------------------------------------------------------------------------------------------------


          Table 12--Combined Estimated Exposures of Marine Mammals to the Pier Implosions for Levels A and B, and Mortality Threshold Criteria
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                     Level B exposures for all                      Level A exposures \1\
                                                             implosions            ------------------------------------------------------
                    Species                     -----------------------------------                                                        Mortality \1\
                                                   Behavioral        Temporary          Permanent      Gastro-intestinal    Slight lung
                                                    response      threshold shift    threshold shift      track injury        injury
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pacific Harbor Seal............................               1                  1                  0                  0               0               0
California Sea Lion............................               0                  0                  0                  0               0               0
Northern Elephant Seal.........................               0                  0                  0                  0               0               0
Northern Fur Seal..............................               0                  0                  0                  0               0               0

[[Page 26030]]

 
Bottlenose Dolphin.............................               0                  0                  0                  0               0               0
Harbor Porpoise................................               1                  0                  0                  0               0               0
                                                --------------------------------------------------------------------------------------------------------
    Total......................................               2                  1                  0                  0               0               0
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: \1\ No implosion will occur if any marine mammal is within the Level A or mortality threshold criteria zones.

    Based on the distances to the marine mammal threshold criteria and 
estimated species density, it is not expected that GI tract, lung 
injury, or mortality could occur from the pier implosion event. 
Approximately two harbor seals (one by behavioral response and one by 
TTS) and one harbor porpoise (by behavioral response) may be taken by 
Level B harassment during the implosion Piers E19 and E20 (Table 11). 
No take of any other species is anticipated.
    The estimated number of marine mammals to be exposed to implosion 
SPLs for each threshold criteria (Table 12) are based on current 
density estimates or occurrence of marine mammals in the project area 
(Table 8 through 11). However, the number of marine mammals in the area 
at any given time is highly variable. Animal movement depends on time 
of day, tide levels, weather, and availability and distribution of prey 
species. Therefore, Caltrans requests the following number of allowable 
harassment takes for each Level B harassment criteria threshold (Table 
13).

         Table 13--Amount of Level B Harassment Take Requested for the Implosions of Piers E19 and E20.
----------------------------------------------------------------------------------------------------------------
                                                                                 Level B harassment take \1\
                                                                           -------------------------------------
                                  Species                                       Behavioral         Temporary
                                                                                 response       threshold shift
----------------------------------------------------------------------------------------------------------------
Pacific Harbor Seal.......................................................                 20                 10
California Sea Lion.......................................................                  4                  3
Northern Elephant Seal....................................................                  2                  1
Northern Fur Seal.........................................................                  2                  1
Harbor Porpoise...........................................................                  5                  5
Bottlenose Dolphin........................................................                  4                  2
                                                                           -------------------------------------
    Total.................................................................                 42                 25
----------------------------------------------------------------------------------------------------------------
Note: \1\ Pier implosion will be delayed if any marine mammals are detected within any of the Level A or
  mortality threshold criteria exclusion zones.

    Pacific Harbor Seal: As discussed above, harbor seal is the most 
numerous marine mammal in the Bay. However, take calculated based on 
species density and the distances to the marine mammal threshold 
criteria indicated that only two harbor seals will be exposed to sound 
pressure levels that can result in Level B harassment (Table 12). One 
of those exposures may be within the Level B monitoring zone, and one 
may be within the TTS zone (Table 12). Based on previous monitoring the 
number of harbor seals in the water can vary greatly, depending on 
weather conditions or the availability of prey. For example, during 
Pacific herring runs further north in the Bay (near Richardson Bay) in 
February 2014, very few harbor seals were observed foraging near YBI or 
transiting through the project area for approximately 2 weeks. 
Sightings went from a high of 27 harbor seal individuals foraging or in 
transit in one day to no seals per day in transit or foraging through 
the project area (Department 2014). In 2015 and 2016, the number of 
harbor seal sighting in a single day in the project area increased up 
to 41 seals (Department 2015b, 2016). Because of this high degree of 
variability, and the observation of up to 41 seals in the project area 
in a single day Caltrans are requesting authorization for the take of 
30 harbor seals by Level B harassment (20 by Level B behavioral 
response and 10 by Level B TTS) (Table 13).
    California Sea Lion: As discussed above, California sea lion is the 
second most numerous marine mammal species in the Bay, after the harbor 
seal. However, take calculated based on species density and the 
distances to the marine mammal threshold criteria indicated that no sea 
lions will be exposed to sound pressure levels that can result in Level 
B harassment (Table 12). Based on previous monitoring the number of sea 
lions transiting through or foraging in the project area can vary 
greatly. Because of the high degree of variability, regular observation 
of sea lions in the project area, and because this species may travel 
in groups Caltrans are requesting authorization for the take of seven 
sea lions (four by Level B behavioral response and three by Level B 
TTS) (Table 11).
    Harbor Porpoises: Based on the calculated density estimates and the 
distances to the marine mammal threshold criteria, one harbor porpoise 
(by behavioral response) may be taken by Level B harassment during the 
implosion of Piers E19 and E20 (Table 12). However the number of harbor 
porpoise in the Bay and their foraging range appears to be steadily 
increasing. This high-frequency cetacean has a large ZOI, because of 
its sensitivity to anthropogenic sound. Further, this species generally 
travels in either calf cow pairs or small pods of four to five 
porpoises. For these reasons Caltrans are

[[Page 26031]]

requesting authorization for the take of 10 harbor porpoise (five by 
Level B behavioral response and five by Level B TTS) (Table 13).
    Northern Elephant Seal: As discussed above, because of the 
infrequent observation of this species in the Bay, Caltrans estimates 
that no elephant seals will be exposed to SPLs that can result in Level 
B harassment (Table 12). However, the number of elephant seals that may 
enter and or strand in the Bay in a given year is highly variable; 
dependent on changes in oceanographic conditions, effecting water 
temperature and prey availability. Caltrans wants to ensure that the 
project has coverage for the incidental take of any species with the 
potential to be present in the project area. Therefore, Caltrans are 
requesting authorization for the take of three elephant seals (two by 
Level B behavioral response and one by Level B TTS) (Table 13).
    Northern Fur Seal: As discussed above, northern fur seals are found 
infrequently in the Bay and are unlikely to be in the vicinity of the 
pier implosion. However, the number of fur seals that may enter and or 
strand in the Bay in a given year is highly variable; dependent on 
changes in oceanographic conditions, effecting water temperature and 
prey availability. Caltrans wants to ensure that the project has 
coverage for the incidental take of any species with the potential to 
be present in the project area. Therefore, they are requesting 
authorization for the take of three northern fur seals (two by Level B 
behavioral response and one by Level B TTS) (Table 13).
    Bottlenose Dolphin: As discussed above, only small numbers of 
bottlenose dolphin occur in the project vicinity. Based on the low 
number of individuals in the Bay and the distances to the marine mammal 
threshold criteria Caltrans anticipates that no bottlenose dolphins 
will be exposed to SPLs that can result in Level B harassment. However, 
as discussed in Chapter 4, until 2016, most bottlenose dolphins in the 
Bay were observed in the western Bay, from the Golden Gate Bridge to 
Oyster Point and Redwood City, although one individual was observed 
frequently near the former Alameda Air Station (Perlman 2017). As of 
2017, the same two individuals have been observed regularly near 
Alameda (Keener, pers. comm., 2017) and likely pass by the project 
area. If additional individuals begin using this eastern area of the 
Bay, the number of bottlenose sightings near the project area will 
likely increase. Caltrans wants to ensure that the project has coverage 
for the incidental take of any species with the potential to be present 
in the project area. Therefore, they are requesting authorization for 
the take of six bottlenose dolphins (four by Level B behavioral 
response and two by Level B TTS) (Table 13).
Take From Pile Driving
    The numbers of marine mammals by species that may be taken by pile 
driving were calculated based on distance to the marine mammal 
threshold criteria, days of driving, and the estimated density of each 
species in the ZOI, for the species that density could be determined. 
The distances to the relevant Level A and B zones are listed above in 
Table 7. Because the sizes of piles, types of piles, or installation 
methods to be used are unknown at this time, the take estimate has been 
prepared based on a worst case scenario. The Level B take estimate is 
based on 60 days of pile driving to install 200 piles, 36 inches (0.91 
meters) in diameter, with a vibratory hammer, as this results in the 
largest Level B zone for a precautionary approach. The Level A take 
estimate is based on 60 days of pile driving to install 200 piles, 36 
inches (0.91 meters) in diameter, with an impact hammer, which has a 
larger Level A zone than vibratory driving, using of an air bubble 
curtain sound attenuation system. The take of each species was 
calculated based on species density (Table 8), for the species that 
density could be determined, over the entire area of each threshold 
criteria zone as shown in Figures 14 and 15 in the application. The 
numbers used for take calculation are shown in Table 14.

                                Table 14--Estimated Take of Marine Mammals from Pile Driving and Pile Removal Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
 
--------------------------------------------------------------------------------------------------------------------------------------------------------
Species                                             Species      Species      Level B      Level B        Per day      Days of      Level B      Level B
                                                      density      density    ZOI radii     ZOI area         take         pile         take         take
                                                    (animals/    (animals/     (meters)      (square      level B      driving   calculated    requested
                                                       square       square               kilometers)
                                                   kilometer)      meters)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Harbor Seal.....................................         3.96     3.96E-06        2,000         9.10        36.01           60     2,160.77         2161
Sea Lion........................................         0.16     1.61E-07        2,000         9.10         1.47           60        87.92           88
Harbor Porpoise.................................         0.17     1.67E-07        2,000         9.10         1.52           60        91.19           91
Bottlenose Dolphin..............................           NA           NA        2,000         9.10           NA           60           NA           30
Elephant Seal...................................           NA           NA        2,000         9.10           NA           60           NA           12
Gray Whale......................................           NA           NA        2,000         9.10           NA           60           NA            4
Fur Seal........................................           NA           NA        2,000         9.10           NA           60           NA            6
                                                 -------------------------------------------------------------------------------------------------------
    Total Level B Take..........................  ...........  ...........  ...........  ...........  ...........  ...........  ...........        2,392
--------------------------------------------------------------------------------------------------------------------------------------------------------
Species                                               Species      Species      Level A      Level A      Per day      Days of      Level A      Level A
                                                      density      density    ZOI radii     ZOI area         take         pile         take         take
                                                    (animals/    (animals/     (meters)      (square      level A      driving   calculated    requested
                                                       square       square               kilometers)                                                 \1\
                                                   kilometer)      meters)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Harbor Seal.....................................         3.96     3.96E-06          206        0.163         0.65           60        38.69          120
Sea Lion........................................         0.16     1.61E-07           15        0.007        0.001           60        0.065            0
Harbor Porpoise.................................         0.17     1.67E-07          459         0.70        0.119           60         6.71            0
Bottlenose Dolphin..............................           NA           NA           15        0.007           NA           60           NA            0
Elephant Seal...................................           NA           NA          206        0.163           NA           60           NA            2
Gray Whale......................................           NA           NA          386        0.488           NA           60           NA            0
Fur Seal........................................           NA           NA           15        0.007           NA           60           NA            0
                                                 -------------------------------------------------------------------------------------------------------
    Total Level A Take \1\......................  ...........  ...........  ...........  ...........  ...........  ...........  ...........          122
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Impact pile driving will not begin if a marine mammal other than phocid pinnipds are within PTS, Level A, shutdown zone. Therefore, only phocids
  will be taken by Level A harassment.


[[Page 26032]]

    Caltrans estimates a maximum of 2,392 instances of take by Level B 
harassment may occur to seven stocks of marine mammal during pile-
driving activities (Table 14). These individuals will be exposed 
temporarily to continuous (vibratory pile driving and removal) sounds 
greater than 120 dB rms and impulse (impact driving) sounds greater 
than 160 dB rms. The majority of the animals taken by Level B 
harassment will be harbor seals (Table 14), the most numerous marine 
mammals in the project area. Although Level A take of marine mammals 
was calculated based on distances to the threshold, density of the 
species, and duration of the activity, Caltrans did not anticipate any 
individuals will be taken by Level A harassment. However, based on 
correspondence from the Marine Mammal Commission, NMFS is authorizing 
Level A take of 120 harbor seals and two elephant seals. This increase 
in potential Level A take is based upon an assumed take of two harbor 
seals per day with 60 days of pile driving. To make sure mitigation and 
monitoring zones are clear and practicable, Caltrans will use one 
monitoring zone for both phocid species, and therefore also requested 
Level A take of two elephant seals. With monitoring and establishment 
of shutdown zones, discussed in the Mitigation section below, Caltrans 
plans to avoid, and NMFS did not authorize, Level A harassment of other 
marine mammal species.
    The number of takes requested, and authorized, by Caltrans are 
based on a calculation of marine mammal density multiplied by the daily 
isopleth multiplied by the number of days of pile driving. However, due 
to variability in sightings of northern elephant seal, northern fur 
seal, bottlenose dolphin, and gray whale, take estimates were adjusted 
using species specific monitoring data detailed below.
    Northern Elephant Seal: Based on low number of elephant seal 
sightings in the project area, Caltrans anticipates that very few if 
any elephant seals will be exposed to continuous sounds greater than 
120 dB rms and impulse sounds greater than 160 dB rms during pile 
driving. No elephant seals have been observed in the immediate project 
vicinity. However, the number of elephant seals that may enter and or 
stand in the Bay in a given year is highly variable; dependent of 
changes in oceanographic conditions, effecting water temperature and 
prey availability. Further, the size of the Level B harassment zone is 
large, extending 2,000 meters (6,562 feet) from the pile driving site. 
Pile driving may take place for up to 60 days and many of the driving 
days will be consecutive. This 60 day window also includes removal of 
temporary piles through vibratory removal or cutting off piles below 
the mudline. Should an elephant seal or multiple elephant seals be in 
the vicinity of the project area for multiple days they could be taken 
several times. To ensure Caltrans has coverage for the incidental take 
of any species with the potential to be present in the project area, we 
are proposing to authorize take of 12 elephant seals by Level B 
harassment during pile driving activities (Table 14). This equates to 
the take of one elephant seal during 20 percent of the driving days.
    Northern fur seal: No fur seals have been observed in the immediate 
project vicinity. Should a fur seal or multiple fur seals be in the 
vicinity of the project area for multiple days they could be taken 
several times. To ensure Caltrans has necessary coverage for occasion 
fur seals in the area, we propose to authorize take of up to six 
northern fur seals by Level B harassment during pile driving activities 
(Table 14). This equates to the take of one elephant seal during 10 
percent of the driving days.
    Bottlenose dolphin: Only small numbers of bottlenose dolphin occur 
in the project vicinity. Until 2016, most bottlenose dolphins in the 
Bay were observed in the western Bay, from the Golden Gate Bridge to 
Oyster Point and Redwood City, although one individual was observed 
frequently near the former Alameda Air Station (Perlman 2017). As of 
2017, the same two individuals have been observed regularly near 
Alameda (Keener, pers. comm., 2017) are likely pass by the project 
area. If additional individuals begin using this eastern area of the 
Bay, the number of bottlenose dolphin sightings near the project area 
will likely increase. It is possible that the same two resident 
bottlenose dolphins and or additional individuals could be taken 
multiple times during the up to 60 days of pile driving. Therefore, 
Caltrans is requesting authorization for the take of 90 bottlenose 
dolphins by Level B harassment during pile driving activities. This 
equates to the take of 1.5 bottlenose dolphins during each day of pile 
driving.
    Gray whale: No gray whales have been observed within 2,000 meters 
(6,562 feet) of the project area, but they have been observed just 
north of Treasure Island and southwest of Oakland Middle Harbor. 
According to TMMC, two to six gray whales enter the Bay each year in 
late winter through spring (February through April), presumably to 
feed. Caltrans wants to ensure that the project has coverage for the 
incidental take of any species with the potential to be present in the 
project area. Therefore, Caltrans is requesting authorization for the 
take of 4 grey whales by Level B harassment during pile driving 
activities.

                                 Table 15--Combined Total Take Requested for Pier Implosion and Pile-Driving Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          Pier implosion Level B harassment
                                                        take                     Pile driving                                          Requested take as
                Species                --------------------------------------      Level B         Total Level B      Total Level A     percent of stock
                                            Behavioral         Temporary       harassment take    harassment Take          take            abundance
                                             response       threshold shift
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pacific Harbor Seal...................                 20                 10              2,161              2,191                120                7.5
California Sea Lion...................                  4                  3                 88                 95                  0                .03
Northern Elephant Seal................                  2                  1                 12                 15                  2                .01
Northern Fur Seal.....................                  2                  1                  6                  9                  0                .06
Harbor Porpoise.......................                 10                  8                 91                109                  0                1.1
Bottlenose Dolphin....................                  4                  2                 30                 36                  0                  8
Gray Whale............................                  0                  0                  4                  4                  0                .02
--------------------------------------------------------------------------------------------------------------------------------------------------------


[[Page 26033]]

Mitigation

    In order to issue an IHA under Section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to such 
activity, and other means of effecting the least practicable impact on 
such species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of such species or stock for taking for certain 
subsistence uses (latter not applicable for this action). NMFS 
regulations require applicants for incidental take authorizations to 
include information about the availability and feasibility (economic 
and technological) of equipment, methods, and manner of conducting such 
activity or other means of effecting the least practicable adverse 
impact upon the affected species or stocks and their habitat (50 CFR 
216.104(a)(11)).
    In evaluating how mitigation may or may not be appropriate to 
ensure the least practicable adverse impact on species or stocks and 
their habitat, as well as subsistence uses where applicable, we 
carefully consider two primary factors:
    (1) The manner in which, and the degree to which, the successful 
implementation of the measure(s) is expected to reduce impacts to 
marine mammals, marine mammal species or stocks, and their habitat. 
This considers the nature of the potential adverse impact being 
mitigated (likelihood, scope, range). It further considers the 
likelihood that the measure will be effective if implemented 
(probability of accomplishing the mitigating result if implemented as 
planned) the likelihood of effective implementation (probability 
implemented as planned); and
    (2) The practicability of the measures for applicant 
implementation, which may consider such things as cost, impact on 
operations, and, in the case of a military readiness activity, 
personnel safety, practicality of implementation, and impact on the 
effectiveness of the military readiness activity.

Mitigation for Marine Mammals and Their Habitat

    Pier Implosions--The decision to combine two smaller piers into 
single, sequential blast events will further reduce potential impacts 
on marine mammals. This will allow faster completion of the project and 
will reduce the total number of pier implosion events (days where pier 
implosions occur).
    BAS--As described previously in this document, a BAS will be used 
around both piers during the implosion. Based on the results of 
acoustic monitoring for the previous pier implosions, BAS performance 
is anticipated to provide approximately 70 to 80 percent attenuation of 
implosion-related pressure waves.
    Implosion shutdown zone--During the implosion of Piers E19 and E20, 
a project-specific monitoring plan will be implemented to avoid the 
potential for individual exposure to Level A harassment, and to 
document the number and species potentially exposed to Level B 
harassment. This plan will be similar to the Marine Foundation Removal 
Project Final Biological Monitoring Program, previously approved by 
NMFS, that was implemented during the implosions of Piers E6 to E18. In 
particular, monitors will observe the shutdown zone and will delay the 
implosion if any individuals are within this zone. The same procedure 
was implemented successfully for the implosions of Piers E3 through 
E18, and no marine mammals were exposed to SPLs above the Level A or 
mortality threshold criteria. This project-specific monitoring plan 
will be transmitted to NMFS before the implosions, for review and 
concurrence.
    Pile driving--All steel pipe piles initially will be installed with 
a vibratory hammer. The vibratory hammer will be used to drive the 
majority of the total pile lengths. In the event that a pipe pile is 
installed entirely with a vibratory hammer, it still will be subject to 
final proof testing with an impact hammer. A maximum of 10 percent of 
the piles installed completely with a vibratory hammer may be proof-
tested with an impact hammer, without the use of a marine pile-driving 
energy attenuator. Proofing of piles will be limited to a maximum of 
two piles per day, for less than 1 minute per pile, administering a 
maximum of 20 blows per pile. Although both vibratory and impact pile 
driving have the potential to affect marine mammals, impact driving is 
expected to generate higher SPLs. Requiring the use of the vibratory 
hammer will reduce the duration of impact driving and potential 
exposure to higher SPLs.
    Pile driving energy attenuator--Use of a marine pile-driving energy 
attenuator (i.e., air bubble curtain system), or other equally 
effective sound attenuation method (e.g., dewatered cofferdam), will be 
required by Caltrans during impact driving of all steel pipe piles 
(with the exception of pile proof-testing). Requiring the use of sound 
attenuation will reduce SPLs and the size of the ZOIs for Level A and 
Level B harassment.
    Pile Driving Shutdown Zone--Before the start of impact pile-driving 
activities, the shutdown zones will be established. The shutdown zones 
are intended to include all areas where the underwater SPLs are 
anticipated to equal or exceed thresholds for injury for species other 
than harbor seals--PTS Level A harassment thresholds for the specific 
species hearing groups, shown in Table 3. The shutdown zone for phocid 
pinnipeds, for which Level A take is requested, is 25 meters. NMFS-
approved observers will survey the shutdown zones for 30 minutes before 
pile-driving activities start. If marine mammals are found within the 
shutdown zones, pile driving will be delayed until the animal has moved 
out of the shutdown zone, either verified through sighting by an 
observer or by waiting until enough time has elapsed without a 
sighting, 15 minutes for pinnipeds and small cetaceans (harbor porpoise 
and bottlenose dolphin), and 30 minutes for gray whale, to be able to 
assume that the animal has moved beyond the zone. With implementation 
of this avoidance and minimization measure, exposure of marine mammals 
to SPLs that can result in PTS Level A harassment will be avoided for 
all species except harbor seals and elephant seals. Due to the resident 
nature of harbor seals, and their ability to appear undetected in close 
range to construction activities, Caltrans is requesting Level A take 
of 120 harbor seals and two elephant seals.
    A 10 meter shutdown zone for all marine mammals will also be 
implemented for in-water heavy machinery work that is not pile driving 
or pier implosion. Similarly, if a marine mammal for which take is not 
authorized is seen within the monitoring zone, operations will cease 
until the animal is seen leaving the zone or until 15 minutes have 
passed.
    Based on our evaluation of the applicant's proposed measures, NMFS 
has determined that the mitigation measures provide the means effecting 
the least practicable impact on the affected species or stocks and 
their habitat, paying particular attention to rookeries, mating 
grounds, and areas of similar significance.

Monitoring and Reporting

    In order to issue an IHA for an activity, Section 101(a)(5)(D) of 
the MMPA states that NMFS must set forth, requirements pertaining to 
the monitoring and reporting of such taking. The MMPA implementing 
regulations at 50 CFR 216.104 (a)(13) indicate that

[[Page 26034]]

requests for authorizations must include the suggested means of 
accomplishing the necessary monitoring and reporting that will result 
in increased knowledge of the species and of the level of taking or 
impacts on populations of marine mammals that are expected to be 
present in the action area. Effective reporting is critical both to 
compliance as well as ensuring that the most value is obtained from the 
required monitoring.
    Monitoring and reporting requirements prescribed by NMFS should 
contribute to improved understanding of one or more of the following:
     Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density);
     Nature, scope, or context of likely marine mammal exposure 
to potential stressors/impacts (individual or cumulative, acute or 
chronic), through better understanding of: (1) Action or environment 
(e.g., source characterization, propagation, ambient noise); (2) 
affected species (e.g., life history, dive patterns); (3) co-occurrence 
of marine mammal species with the action; or (4) biological or 
behavioral context of exposure (e.g., age, calving or feeding areas);
     Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;
     How anticipated responses to stressors impact either: (1) 
Long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
     Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and
     Mitigation and monitoring effectiveness.

Visual Marine Mammal Observations

    Caltrans will collect sighting data and behavioral responses to 
construction for marine mammal species observed in the region of 
activity during the period of activity. All protected species observers 
(PSOs) will be trained in marine mammal identification and behaviors 
and are required to have no other construction-related tasks while 
conducting monitoring. A minimum of two PSOs will be required for all 
pile driving activities. Caltrans will establish shutdown zones, 
similar to those detailed in Table 7, as well as a monitoring zone of 
2,000 meters for all marine mammals. Caltrans will monitor the shutdown 
zone and monitoring zone 30 minutes before, during, and 30 minutes 
after pile driving, with observers located at the best practicable 
vantage points. For implosion activities, Caltrans will monitor the 
area for 60 minutes after implosions. Caltrans also plans to conduct 
post-implosion surveys on shore and by vessel immediately after 
implosion events and for the following two days to search for any dead 
or injured marine mammals. Based on our requirements, Caltrans will 
implement the following procedures:
     PSOs will be located at the best vantage point(s) in order 
to properly see the entire shutdown zone and as much of the disturbance 
zone as possible;
     During all observation periods, observers will use 
binoculars and the naked eye to search continuously for marine mammals;
     If the shutdown zones are obscured by fog or poor lighting 
conditions, pile driving at that location will not be initiated until 
that zone is visible. Should such conditions arise while impact driving 
is underway, the activity will be halted; and
     The shutdown zone and observable portion of the monitoring 
zone around the pile will be monitored for the presence of marine 
mammals 30 min before, during, and 30 min after any pile driving 
activity.

Data Collection

    We require that observers use approved data forms. Among other 
pieces of information, Caltrans will record detailed information about 
any implementation of shutdowns, including the distance of animals to 
the pile and description of specific actions that ensued and resulting 
behavior of the animal, if any. In addition, Caltrans will attempt to 
distinguish between the number of individual animals taken and the 
number of incidences of take. We require that, at a minimum, the 
following information be collected on the sighting forms:
     Date and time that monitored activity begins or ends;
     Construction activities occurring during each observation 
period;
     Weather parameters (e.g., percent cover, visibility);
     Water conditions (e.g., sea state, tide state);
     Species, numbers, and, if possible, sex and age class of 
marine mammals;
     Description of any observable marine mammal behavior 
patterns, including bearing and direction of travel, and if possible, 
the correlation to SPLs;
     Distance from pile driving activities to marine mammals 
and distance from the marine mammals to the observation point;
     Description of implementation of mitigation measures 
(e.g., shutdown or delay);
     Locations of all marine mammal observations; and
     Other human activity in the area.

Reporting

    A draft report will be submitted to NMFS within 90 days of the 
completion of marine mammal monitoring, or 60 days prior to the 
requested date of issuance of any future IHA for projects at the same 
location, whichever comes first. The report will include marine mammal 
observations pre-activity, during-activity, and post-activity during 
pile driving days, and will also provide descriptions of any behavioral 
responses to construction activities by marine mammals and a complete 
description of all mitigation shutdowns and the results of those 
actions and an extrapolated total take estimate based on the number of 
marine mammals observed during the course of construction. A final 
report must be submitted within 30 days following resolution of 
comments on the draft report.

Negligible Impact Analysis and Determination

    NMFS has defined negligible impact as an impact resulting from the 
specified activity that cannot be reasonably expected to, and is not 
reasonably likely to, adversely affect the species or stock through 
effects on annual rates of recruitment or survival (50 CFR 216.103). A 
negligible impact finding is based on the lack of likely adverse 
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough 
information on which to base an impact determination. In addition to 
considering estimates of the number of marine mammals that might be 
``taken'' through harassment, NMFS considers other factors, such as the 
likely nature of any responses (e.g., intensity, duration), the context 
of any responses (e.g., critical reproductive time or location, 
migration), as well as effects on habitat, and the likely effectiveness 
of the mitigation. We also assess the number, intensity, and context of 
estimated takes by evaluating this information relative to population 
status. Consistent with the 1989 preamble for NMFS's implementing 
regulations (54 FR 40338; September 29, 1989), the impacts from other 
past and ongoing anthropogenic activities are

[[Page 26035]]

incorporated into this analysis via their impacts on the environmental 
baseline (e.g., as reflected in the regulatory status of the species, 
population size and growth rate where known, ongoing sources of human-
caused mortality, or ambient noise levels).
    Pile driving and pier implosion activities associated from the 
Caltrans project, as outlined previously, have the potential to disturb 
or displace marine mammals. Specifically, the specified activities may 
result in take, in the form of Level B harassment (TTS and behavioral 
disturbance), from underwater sounds generated from pier implosions and 
pile driving. Potential takes could occur if individuals of these 
species are present in the ensonified zone when pile driving or 
implosion occurs. A few marine mammals could experience TTS if they 
occur within the Level B TTS zone. However, TTS is a temporary loss of 
hearing sensitivity when exposed to loud sound, and the hearing 
threshold is expected to recover completely within minutes to hours. 
Therefore, it is not considered an injury. In addition, even if an 
animal receives a TTS, the TTS will be a one-time event from a brief 
impulse noise (about 5 seconds), making it unlikely that the TTS will 
lead to PTS. If an animal undergoes a TTS from pier implosion, it is 
likely to recover quickly as there is only one implosion event planned. 
Finally, there is no critical habitat or other biologically important 
areas in the vicinity of Caltrans' controlled implosion areas 
(Calambokidis et al., 2015).
    No serious injury or mortality is anticipated given the nature of 
the activities and measures designed to minimize the possibility of 
injury to marine mammals. The potential for these outcomes is minimized 
through the construction method and the implementation of the planned 
mitigation measures. Specifically, Caltrans will use a blast 
attenuation system for the pier implosion, which it has previously used 
successfully. For pile driving activities, vibratory and impact hammers 
will be the primary methods of pier installation. Impact pile driving 
produces short, sharp pulses with higher peak levels and much sharper 
rise time to reach those peaks. If impact driving is necessary, 
implementation of soft start and shutdown zones significantly reduces 
any possibility of injury. Given sufficient ``notice'' through use of 
soft start (for impact driving), marine mammals are expected to move 
away from a sound source that is annoying prior to it becoming 
potentially injurious. Caltrans will use a minimum of two PSOs 
stationed strategically to increase detectability of marine mammals, 
enabling a high rate of success in implementation of shutdowns to avoid 
injury for all species except harbor seal.
    Caltrans' activities are localized and of relatively short duration 
(June to November). This duration does not overlap with breeding, 
pupping, or other biologically significant events for marine mammal 
species in the area. The project area is also very limited in scope 
spatially, as all work is concentrated on the edges of a single bridge 
expanse. These localized and short-term noise exposures may cause 
short-term behavioral modifications in seven marine mammal species. 
Moreover, the mitigation and monitoring measures are expected to 
further reduce the likelihood of injury, as it is unlikely an animal 
will remain in close proximity to the sound source with small Level A 
isopleths. While the project area is known to be frequented by harbor 
seals and California sea lions, it is not an established breeding 
ground for local populations.
    The project also is not expected to have significant adverse 
effects on affected marine mammals' habitat. The project activities 
will not modify existing marine mammal habitat for a significant amount 
of time. The activities may cause some fish to leave the area of 
disturbance, thus temporarily impacting marine mammals' foraging 
opportunities in a limited portion of the foraging range. However, 
because of the short duration of the activities and the relatively 
small area of the habitat that may be affected, and the decreased 
potential of prey species to be in the Project area during the 
construction work window, the impacts to marine mammal habitat are not 
expected to cause significant or long-term negative consequences.
    Effects on individuals that are taken by Level B harassment, on the 
basis of reports in the literature as well as monitoring from other 
similar activities, will likely be limited to temporary reactions such 
as increased swimming speeds, increased surfacing time, flushing, or 
decreased foraging (if such activity were occurring) (e.g., Thorson and 
Reyff 2006; Lerma 2014). Most likely, individuals will simply move away 
from the sound source and be temporarily displaced from the areas of 
pile driving and implosions. Thus, even repeated Level B harassment of 
some small subset of the overall stock is unlikely to result in any 
significant realized decrease in fitness for the affected individuals, 
and thus will not result in any adverse impact to the stock as a whole. 
For some stocks, such as harbor seal, more animal presence has 
increased in recent years, despite Caltrans' work in the area.
    In summary and as described above, the following factors primarily 
support our determination that the impacts resulting from this activity 
are not expected to adversely affect the species or stock through 
effects on annual rates of recruitment or survival:
     No mortality is anticipated or authorized;
     No more than 10 individuals per species are expected to 
incur TTS during pier implosion. No TTS is expected to occur during 
pile driving. The size of the zones in which TTS is expected to occur 
are small and will be heavily monitored per the measures outlined above 
in the Monitoring section;
     Level B harassment may consist of temporary modifications 
in behavior (e.g., temporary avoidance of habitat or changes in 
behavior);
     The lack of important feeding, pupping, or other 
biologically significant areas in the action area during the 
construction window;
     The small impact area relative to species range size;
     Mitigation is expected to minimize the likelihood and 
severity of the level of harassment; and
     The small percentage of the stock that may be affected by 
project activities (< eight percent for all stocks).
    Based on the analysis contained herein of the likely effects of the 
specified activity on marine mammals and their habitat, and taking into 
consideration the implementation of the monitoring and mitigation 
measures, NMFS finds that the total marine mammal take from the 
activity will have a negligible impact on all affected marine mammal 
species or stocks.

Small Numbers

    As noted above, only small numbers of incidental take may be 
authorized under Section 101(a)(5)(D) of the MMPA for specified 
activities other than military readiness activities. The MMPA does not 
define small numbers and so, in practice, where estimated numbers are 
available, NMFS compares the number of individuals taken to the most 
appropriate estimation of abundance of the relevant species or stock in 
our determination of whether an authorization is limited to small 
numbers of marine mammals. Additionally, other qualitative factors may 
be considered in the analysis, such as the temporal or spatial scale of 
the activities.

[[Page 26036]]

    Table 15 above details the number of individuals that could be 
exposed to received noise levels that could cause TTS or Level B 
harassment for the work at the project site relative to the total stock 
abundance. The numbers of animals authorized to be taken for all 
species will be considered small relative to the relevant stocks or 
populations even if each estimated instance of take occurred to a new 
individual. The total percent of the population (if each instance was a 
separate individual) for which take is requested is less than eight 
percent for all stocks (Table 15). Based on the analysis contained 
herein of the activity (including the mitigation and monitoring 
measures) and the anticipated take of marine mammals, NMFS finds that 
small numbers of marine mammals will be taken relative to the 
population size of the affected species or stocks.

Unmitigable Adverse Impact Analysis and Determination

    There are no relevant subsistence uses of the affected marine 
mammal stocks or species implicated by this action. Therefore, NMFS has 
determined that the total taking of affected species or stocks will not 
have an unmitigable adverse impact on the availability of such species 
or stocks for taking for subsistence purposes.

Endangered Species Act (ESA)

    Section 7(a)(2) of the Endangered Species Act of 1973 (ESA: 16 
U.S.C. 1531 et seq.) requires that each Federal agency insure that any 
action it authorizes, funds, or carries out is not likely to jeopardize 
the continued existence of any endangered or threatened species or 
result in the destruction or adverse modification of designated 
critical habitat. To ensure ESA compliance for the issuance of IHAs, 
NMFS consults internally, in this case with the West Coast Region 
Protected Resources Division Office, whenever we propose to authorize 
take for endangered or threatened species.
    No incidental take of ESA-listed species is authorized or expected 
to result from this activity. Therefore, NMFS has determined that 
consultation under Section 7 of the ESA is not required for this 
action.

Authorization

    NMFS has issued an IHA to Caltrans for the harassment of small 
numbers of marine mammals incidental to the dismantling and reuse of 
the original East Span of the San Francisco-Oakland Bay Bridge in the 
San Francisco Bay provided the previously mentioned mitigation, 
monitoring, and reporting requirements.

    Dated: May 31, 2018.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2018-12043 Filed 6-4-18; 8:45 am]
 BILLING CODE 3510-22-P