[Federal Register Volume 80, Number 185 (Thursday, September 24, 2015)]
[Notices]
[Pages 57584-57596]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-24230]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XE030


Taking of Marine Mammals Incidental to Specified Activities; San 
Francisco-Oakland Bay Bridge Pier E3 Demolition via Controlled 
Implosion

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

ACTION: Notice; issuance of an incidental take authorization.

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SUMMARY: In accordance with the Marine Mammal Protection Act (MMPA) 
regulations, notification is hereby given that NMFS has issued an 
Incidental Harassment Authorization (IHA) to the California Department 
of Transportation (CALTRANS) to take, by harassment, small numbers of 
four species of marine mammals incidental to the San Francisco-Oakland 
Bay Bridge (SFOBB) Pier E3 demolition via controlled implosion in San 
Francisco Bay (SFB or Bay), between October 1 and December 30, 2015.

DATES: Effective October 1, 2015, through December 30, 2015.

[[Page 57585]]


ADDRESSES: Requests for information on the incidental take 
authorization should be addressed to Jolie Harrison, Chief, Permits and 
Conservation Division, Office of Protected Resources, National Marine 
Fisheries Service, 1315 East-West Highway, Silver Spring, MD 20910. A 
copy of the application containing a list of the references used in 
this document, NMFS' Environmental Assessment (EA), Finding of No 
Significant Impact (FONSI), and the IHA may be obtained by writing to 
the address specified above or visiting the Internet at: http://www.nmfs.noaa.gov/pr/permits/incidental/. Documents cited in this 
notice may be viewed, by appointment, during regular business hours, at 
the aforementioned address.

FOR FURTHER INFORMATION CONTACT: Shane Guan, Office of Protected 
Resources, NMFS, (301) 427-8401.

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 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.''
    Section 101(a)(5)(D) of the MMPA established an expedited process 
by which citizens of the U.S. can apply for a one-year authorization to 
incidentally take small numbers of marine mammals by harassment, 
provided that there is no potential for serious injury or mortality to 
result from the activity. Section 101(a)(5)(D) establishes a 45-day 
time limit for NMFS review of an application followed by a 30-day 
public notice and comment period on any proposed authorizations for the 
incidental harassment of marine mammals. Within 45 days of the close of 
the comment period, NMFS must either issue or deny the authorization.

Summary of Request

    On March 3, 2015, CALTRANS submitted a request to NMFS for the 
potential harassment of small numbers of marine mammals incidental to 
the dismantling of Pier E3 of the East Span of the original SFOBB in 
SFB, California, in fall 2015. CALTRANS is proposing to remove the Pier 
E3 via highly controlled implosion with detonations. On April 16, 2015, 
CALTRANS submitted a revision of its request with an inclusion of a 
test implosion before the bridge demolition. NMFS determined that the 
IHA application was complete on May 1, 2015.

Description of the Specified Activity

    A detailed description of the CALTRANS SFOBB East Span Pier E3 
demolition via controlled implosion is provided in the Federal Register 
notice for the proposed IHA (80 FR 44060; July 24, 2015). Since that 
time, no changes have been made to the proposed construction 
activities. Therefore, a detailed description is not provided here. 
Please refer to that Federal Register notice for the description of the 
specific activity.

Comments and Responses

    A notice of NMFS' proposal to issue an IHA to CALTRANS was 
published in the Federal Register on July 24, 2015 (80 FR 44060). 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 public comment period, the NMFS 
received one comment letter from the Marine Mammal Commission 
(Commission). The Commission concurred with NMFS preliminary finding 
and recommended that NMFS issue the requested incidental harassment 
authorization, subject to inclusion of the proposed mitigation, 
monitoring, and reporting measures.

Description of Marine Mammals in the Area of the Specified Activity

    The marine mammal species under NMFS jurisdiction most likely to 
occur in the proposed construction area include Pacific harbor seal 
(Phoca vitulina richardsi), northern elephant seal (Mirounga 
angustirostris), California sea lion (Zalophus californianus), and 
harbor porpoise (Phocoena phocoena).

                    Table 1--Marine Mammal Species Potentially Present in Region of Activity
----------------------------------------------------------------------------------------------------------------
              Species                      ESA status              MMPA status                Occurrence
----------------------------------------------------------------------------------------------------------------
Harbor Seal........................  Not listed............  Non-depleted..........  Frequent.
California Sea Lion................  Not listed............  Non-depleted..........  Occasional.
Northern Elephant Seal.............  Not listed............  Non-depleted..........  Occasional.
Harbor Porpoise....................  Not listed............  Non-depleted..........  Rare.
----------------------------------------------------------------------------------------------------------------

    General information on the marine mammal species found in the San 
Francisco Bay can be found in Caretta et al. (2014), which is available 
at the following URL: http://www.nmfs.noaa.gov/pr/sars/pdf/po2013.pdf. 
Refer to that document for information on these species. A list of 
marine mammals in the vicinity of the action and their status are 
provided in Table 1. Specific information concerning these species in 
the vicinity of the proposed action area is provided in detail in the 
CALTRANS' IHA application.

Potential Effects of the Specified Activity on Marine Mammals

    The underwater impulse noise from controlled implosion for SFOBB 
Pier E9 demolition in San Francisco Bay has the potential to result in 
Level B harassment of marine mammal species and stocks from behavioral 
disturbances and temporary hearing threshold shift (TTS) in the 
vicinity of the action area. The Notice of Proposed IHA included a 
discussion of the effects of anthropogenic noise on marine mammals, 
which is not repeated here. No instances of injury (including permanent 
hearing threshold shift, or PTS), serious injury, or mortality are

[[Page 57586]]

expected as a result of CALTRANS' activity given the mitigation and 
monitoring measures proposed, the brief duration of the activity, and 
the limited scale of the activity.

Potential Effects on Marine Mammal Habitat

    The primary potential impacts to marine mammals and other marine 
species are associated with overpressure generated from the controlled 
underwater implosion, such that some fish in the immediate vicinity of 
the demolition site could be killed. These potential effects are 
discussed in detail in the Federal Register notice for the proposed IHA 
and are not repeated here.

Mitigation Measures

    In order to issue an incidental take authorization 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 adverse 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.
    For CALTRANS' proposed Pier E3 controlled implosion, NMFS is 
requiring CALTRANS to implement the following mitigation measures to 
minimize the potential impacts to marine mammals in the project 
vicinity as a result of the controlled underwater implosion. In 
addition to the measures contained in the Federal Register notice of 
Proposed IHA, the IHA requires CALTRANS to ensure that no harbor 
porpoise Level A harassment take would occur by using passive acoustic 
monitoring to detect harbor porpoise clicks and implement shutdown 
measure if clicks are detected. Furthermore, additional mitigation 
measures are included to ensure that no take would occur during the 
test implosion. No other change was made from the proposed mitigation 
measures published in the Federal Register notice (80 FR 44060; July 
24, 2015) for the proposed IHA.

Time Restriction

    Implosion of Pier E3 will only be conducted during daylight hours 
and with enough time for pre and post implosion monitoring, and with 
good visibility when the largest exclusion zone can be visually 
monitored.

Installation of Blast Attenuation System (BAS)

    Prior to the Pier E3 demolition, CALTRANS should install a Blast 
Attenuation System (BAS) as described above to reduce the shockwave 
from the implosion.

Establishment of Level A Exclusion Zone

    Due to the different hearing sensitivities among different taxa of 
marine mammals, NMFS has established a series of take thresholds from 
underwater explosions for marine mammals belonging to different 
functional hearing groups (Table 2). Under these criteria, marine 
mammals from different taxa will have different impact zones (exclusion 
zones and zones of influence).
    CALTRANS will establish an exclusion zone for both the mortality 
and Level A harassment zone (permanent hearing threshold shift or PTS, 
GI track injury, and slight lung injury) using the largest radius 
estimated harbor and northern elephant seals. Estimates are that the 
isopleth for PTS would extend out to a radius of 1,160 ft (354 m) for 
harbor and northern elephant seals to 5,800 ft (1,768 m) for harbor 
porpoise; covering the entire areas for both Level A harassment and 
mortality. As harbor porpoises are unlikely to be in the area in 
November, the exclusion zone boundaries would be set around the 
calculated distance to Level A harassment for harbor and northern 
elephant seals. However, real-time acoustic monitoring (i.e., active 
listening for vocalizations with hydrophones) also will be utilized to 
provide an additional level of confidence that harbor porpoises are not 
in the affected area.

                   Table 2--NMFS Acoustic Criteria for Marine Mammals in the SFOBB Pier E3 Demolition Area From Underwater Implosions
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                        Level B harassment              Level A                Serious injury
                                                ----------------------------------    harassment    ------------------------------------
            Group                   Species                                       ------------------      Gastro-                           Mortality
                                                   Behavioral           TTS               PTS        intestinal tract        Lung
--------------------------------------------------------------------------------------------------------------------------------------------------------
High-freq cetacean...........  Harbor porpoise.  141 dB SEL....  146 dB SEL or     161 dB SEL or     237 dB SPL or     39.1M\1/3\ (1+[D/ 91.4M\1/3\
                                                                  195 dB SPLpk.     201 dB SPLpk.     104 psi.          10.081])\1/2\     (1+[D/
                                                                                                                        Pa-sec.           10.081])\1/2\
                                                                                                                       where: M = mass    Pa-sec
                                                                                                                        of the animals   where: M = mass
                                                                                                                        in kg.            of the animals
                                                                                                                       D = depth of       in kg
                                                                                                                        animal in m.     D = depth of
                                                                                                                                          animal in m
Phocidae.....................  Harbor seal &     172 dB SEL....  177 dB SEL or     192 dB SEL or
                                northern                          212 dB SPLpk.     218 dB SPLpk.
                                elephant seal.
Otariidae....................  California sea    195 dB SEL....  200 dB SEL or     215 dB SEL or
                                lion.                             212 dBpk.         218 dB SPLpk.
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Note: All dB values are referenced to 1 [micro]Pa. SPLpk = Peak sound pressure level; psi = pounds per square inch.

    Adherence to calculated distances to Level A harassment for 
pinnipeds indicates that the radius of the exclusion zone would be 
1,160 ft (354 m). The exclusion zone will be monitored by protected 
species observers (PSOs) and if any marine mammals are observed inside 
the exclusion, the implosion will be delayed until the animal leaves 
the area or at least 30 minutes have passed since the last observation 
of the marine mammal. Hearing group specific exclusion zone ranges for 
the controlled implosion are provided in Table 3.
    There is no exclusion zone for the test implosion because of the 
small charge to be used.

[[Page 57587]]

Establishment of Level B Temporary Hearing Threshold Shift (TTS) Zone 
of Influence:

    As shown in Table 2, for harbor and northern elephant seals, this 
will cover the area out to 212 dB peak SPL or 177 dB SEL, whichever 
extends out the furthest. Hydroacoustic modeling indicates this 
isopleth would extend out to 5,700 ft (1,737 m) from Pier E3. For 
harbor porpoises, this will cover the area out to 195 dB peak SPL or 
146 dB SEL, whichever extends out the furthest. Hydroacoustic modeling 
indicates this isopleth would extend out to 26,500 ft (8,077 m) from 
Pier E3. As discussed previously, the presence of harbor porpoises in 
this area is unlikely but monitoring (including real-time acoustic 
monitoring) will be employed to confirm their absence. For California 
sea lions, the distance to the Level B TTS zone of influence will cover 
the area out to 212 dB peak SPL or 200 dB SEL. This distance was 
calculated at 470 ft (143 m) from Pier E3, well within the exclusion 
zone previously described. Hearing group specific Level B TTS zone of 
influence ranges for the controlled implosion are provided in Table 3.
    Hearing group specific Level B TTS zone of influence ranges for the 
test implosion are provided in Table 4.

Establishment of Level B Behavioral Zone of Influence

Table 3--Estimated Distance to NMFS Marine Mammal Explosion Criteria for Level B Harassment, Level A Harassment, and Mortality From the Proposed Pier E3
   Implosion. A BAS With 80% Efficiency in Acoustic Attenuation Is Assessed for the Implosion. For Thresholds With Dual Criteria, the Larger Distances
                                     (i.e., More Conservative) Are Presented in Bold and Are Used for Take Estimates
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                             Level B criteria                                  Level A criteria
            Species             -----------------------------------------------------------------------------------------------------      Mortality
                                 Behavioral response   TTS Dual criteria   PTS Dual criteria       GI track           Lung injury
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pacific Harbor Seal............  9,700 ft...........  5,700.............  1,160 ft..........  35 ft.............  450 ft............  205 ft
                                 (2,957 m)..........  (1,737 m).........  (354 m)...........  (11 m)............  (137 m)...........  (63 m).
                                                      440 ft............  70 ft.............
                                                      (134 m)...........  (21 m)............
California Sea Lion............  800 ft.............  470 ft............  245 ft............  35 ft.............  450 ft............  205 ft.
                                 (244 m)............  (143 m)...........  (75 m)............  (11 m)............  (137 m)...........  (63 m).
                                                      440 ft............  97 ft.............
                                                      (134 m)...........  (30 m)............
Northern Elephant Seal.........  9,700 ft...........  5,700 ft..........  1,160 ft..........  35 ft.............  450 ft............  205 ft.
                                 (2,957 m)..........  (1,737 m).........  (354 m)...........  (11 m)............  (137 m)...........  (63 m).
                                                      440 ft............  70 ft.............
                                                      (134 m)...........  (21 m)............
Harbor Porpoise................  44,500 ft..........  26,500 ft.........  5,800 ft..........  35 ft.............  450 ft............  205 ft.
                                 (13,564 m).........  (8,077 m).........  (1,768 m).........  (11 m)............  (137 m)...........  (63 m).
                                                      2,600 ft..........  1,400 ft..........
                                                      (792 m)...........  (427 m)...........
--------------------------------------------------------------------------------------------------------------------------------------------------------

    As shown in Table 2, for harbor seals and northern elephant seals, 
this will cover the area out to 172 dB SEL. Hydroacoustic modeling 
indicates this isopleth would extend out to 9,700 ft (2,957 m) from 
Pier E3. For harbor porpoises, this will cover the area out to 141 dB 
SEL. Hydroacoustic modeling indicates this isopleth would extend out to 
44,500 ft (13,564 m) from Pier E3. As discussed previously, the 
presence of harbor porpoises in this area is unlikely but monitoring 
(including real-time acoustic monitoring) will be employed to confirm 
their absence. For California sea lions, the distance to the Level B 
behavioral harassment ZOI will cover the area out to 195 dB SEL. This 
distance was calculated at 800 ft (244 m) from Pier E3, well within the 
exclusion zone previously described. Hearing group specific Level B 
behavioral zone of influence ranges for the controlled implosion are 
provided in Table 3. There is no Level B behavioral ZOI for the test 
implosion because there would only be one detonation.

  Table 4--Estimated Distances to NMFS Marine Mammal Explosion Criteria
   for Temporary Hearing Threshold Shift (TTS) From the Proposed Test
                                Implosion
------------------------------------------------------------------------
                  Species                            Level B TTS
------------------------------------------------------------------------
Pacific harbor seal........................  45 feet.
California sea lion........................  45 feet.
Northern elephant seal.....................  45 feet.
Harbor porpoise............................  270 feet.
------------------------------------------------------------------------

Delay of Implosion Activities

    If any marine mammal is observed inside the exclusion zone of 
controlled implosion, the implosion will be delayed until the animal 
leaves the area or at least 30 minutes have passed since the last 
observation of the marine mammal.
    If any marine mammal is observed inside the Level B ZOIs during the 
test implosion, the test implosion will be delayed until the animal 
leaves the area or at least 30 minutes have passed since the last 
observation of the marine mammal.
    If harbor porpoise clicks are detected during passive acoustic 
monitoring, the implosion will be delayed for 30 minutes after the 
clicks are ceased.

Communication

    All PSOs will be equipped with mobile phones and a VHF radio as a 
backup. One person will be designated as the Lead PSO and will be in 
constant contact with the Resident Engineer on site and the blasting 
crew. The Lead PSO will coordinate marine mammal sightings with the 
other PSOs and the real time acoustic monitor. PSOs will contact the 
other PSOs when a sighting is made within the exclusion zone or near 
the exclusion zone so that the PSOs within overlapping areas of 
responsibility can continue to track the animal and the Lead PSO is 
aware of the animal. If it is within 30 minutes of blasting and an 
animal has entered the exclusion zone or is near it, the Lead PSO will 
notify the Resident Engineer and blasting crew. The Lead PSO will keep 
them informed of the disposition of the animal.

[[Page 57588]]

Mitigation Conclusions

    NMFS has carefully evaluated the mitigation measures and considered 
a range of other measures in the context of ensuring that NMFS 
prescribes the means of effecting the least practicable impact on the 
affected marine mammal species and stocks and their habitat. Our 
evaluation of potential measures included consideration of the 
following factors in relation to one another:
     The manner in which, and the degree to which, the 
successful implementation of the measure is expected to minimize 
adverse impacts to marine mammals
     The proven or likely efficacy of the specific measure to 
minimize adverse impacts as planned
     The practicability of the measure for applicant 
implementation.
    Any mitigation measure(s) prescribed by NMFS should be able to 
accomplish, have a reasonable likelihood of accomplishing (based on 
current science), or contribute to the accomplishment of one or more of 
the general goals listed below:
    (1) Avoidance or minimization of injury or death of marine mammals 
wherever possible (goals 2, 3, and 4 may contribute to this goal).
    (2) A reduction in the numbers of marine mammals (total number or 
number at biologically important time or location) exposed to received 
levels of pile driving and pile removal or other activities expected to 
result in the take of marine mammals (this goal may contribute to 1, 
above, or to reducing harassment takes only).
    (3) A reduction in the number of times (total number or number at 
biologically important time or location) individuals would be exposed 
to received levels of pile driving and pile removal, or other 
activities expected to result in the take of marine mammals (this goal 
may contribute to 1, above, or to reducing harassment takes only).
    (4) A reduction in the intensity of exposures (either total number 
or number at biologically important time or location) to received 
levels of pile driving, or other activities expected to result in the 
take of marine mammals (this goal may contribute to a, above, or to 
reducing the severity of harassment takes only).
    (5) Avoidance or minimization of adverse effects to marine mammal 
habitat, paying special attention to the food base, activities that 
block or limit passage to or from biologically important areas, 
permanent destruction of habitat, or temporary destruction/disturbance 
of habitat during a biologically important time.
    (6) For monitoring directly related to mitigation--an increase in 
the probability of detecting marine mammals, thus allowing for more 
effective implementation of the mitigation.
    Based on our evaluation of the mitigation measures, as well as 
other measures considered by NMFS, NMFS has determined that the 
mitigation measures provide the means of effecting the least 
practicable impact on marine mammals 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 incidental take authorization (ITA) 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 requests for ITAs 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 proposed action area. CALTRANS submitted a marine 
mammal monitoring plan as part of the IHA application. It can be found 
at http://www.nmfs.noaa.gov/pr/permits/incidental.htm.
    Monitoring measures prescribed by NMFS should accomplish one or 
more of the following general goals:
    (1) An increase in the probability of detecting marine mammals, 
both within the mitigation zone (thus allowing for more effective 
implementation of the mitigation) and in general to generate more data 
to contribute to the analyses mentioned below;
    (2) An increase in our understanding of how many marine mammals are 
likely to be exposed to levels of pile driving that we associate with 
specific adverse effects, such as behavioral harassment, TTS, or PTS;
    (3) An increase in our understanding of how marine mammals respond 
to stimuli expected to result in take and how anticipated adverse 
effects on individuals (in different ways and to varying degrees) may 
impact the population, species, or stock (specifically through effects 
on annual rates of recruitment or survival) through any of the 
following methods:
    [ssquf] Behavioral observations in the presence of stimuli compared 
to observations in the absence of stimuli (need to be able to 
accurately predict received level, distance from source, and other 
pertinent information);
    [ssquf] Physiological measurements in the presence of stimuli 
compared to observations in the absence of stimuli (need to be able to 
accurately predict received level, distance from source, and other 
pertinent information);
    [ssquf] Distribution and/or abundance comparisons in times or areas 
with concentrated stimuli versus times or areas without stimuli;
    (4) An increased knowledge of the affected species; and
    (5) An increase in our understanding of the effectiveness of 
certain mitigation and monitoring measures.

Monitoring Measures

    Monitoring for implosion impacts to marine mammals will be based on 
the SFOBB pile driving monitoring protocol. Pile driving has been 
conducted for the SFOBB construction project since 2000 with 
development of several NMFS-approved marine mammal monitoring plans 
(CALTRANS 2004; 2013). Most elements of these marine mammal monitoring 
plans are similar to what would be required for underwater implosions. 
These monitoring plans would include monitoring an exclusion zone and 
ZOIs for TTS and behavioral harassment described above. In addition, 
CALTRANS shall implement passive acoustic monitoring. All monitoring 
will be conducted by NMFS-approved PSOs. A change is made from the 
Federal Register notice (80 FR 44060; July 24, 2015) for the proposed 
IHA to clarify that a minimum of 10 protected species observers would 
be required for marine mammal monitoring during the controlled 
implosion. No other change was made from the proposed monitoring 
measures published in the Federal Register notice for the proposed IHA.
(1) Protected Species Observers
    A minimum of 8-10 PSOs would be required during the Pier E3 
controlled implosion so that the exclusion zone, Level B Harassment TTS 
and Behavioral ZOIs, and surrounding area can be monitored. One PSO 
would be designated as the Lead PSO and would receive updates from 
other PSOs on the presence or absence of marine mammals within the 
exclusion zone and would notify the Blasting Supervisor of a cleared 
exclusion zone to the implosion.
(2) Monitoring Protocol
    PSOs shall be positioned near the edge of each of the threshold 
criteria zones and shall utilize boats, barges, bridge piers and 
roadway, and sites on Yerba Buena Island and Treasure Island,

[[Page 57589]]

as described in Figure 3 of the CALTRANS Marine Mammal Monitoring Plan. 
The Lead PSO shall be located with the Department Engineer and the 
Blasting Supervisor (or person that will be in charge of detonating the 
charges) during the implosion.
    The Lead PSO will be in contact with other PSOs and the acoustic 
monitors. As the time for the implosion approaches, any marine mammal 
sightings would be discussed between the Lead PSO, the Resident 
Engineer, and the Blasting Supervisor. If any marine mammals enter the 
exclusion zone within 30 minutes of blasting, the Lead PSO will notify 
the Resident Engineer and Blasting Supervisor that the implosion may 
need to be delayed. The Lead PSO will keep them informed of the 
disposition of the animal. If the animal remains in the exclusion zone, 
blasting will be delayed until it has left the exclusion zone. If the 
animal dives and is not seen again, blasting will be delayed at least 
30 minutes. Once the implosion has occurred, the PSOs will continue to 
monitor the area for at least 60 minutes.
(3) Post-Implosion Survey
    Although any injury or mortality from the implosion of Pier E3 is 
very unlikely, boat or shore surveys will be conducted for the three 
days following the event to determine if there are any injured or 
stranded marine mammals in the area. If an injured or dead animal is 
discovered during these surveys or by other means, the NMFS-designated 
stranding team will be contacted to pick up the animal. Veterinarians 
will treat the animal or conduct a necropsy to attempt to determine if 
it stranded was a result of the Pier E3 implosion.
(4) Monitoring Data Collection
    Each PSO will record their observation position, start and end 
times of observations, and weather conditions (sunny/cloudy, wind 
speed, fog, visibility). For each marine mammal sighting, the following 
will be recorded, if possible:

 Species
 Number of animals (with or without pup/calf)
 Age class (pup/calf, juvenile, adult)
 Identifying marks or color (scars, red pelage, damaged dorsal 
fin, etc.)
 Position relative to Pier E3 (distance and direction)
 Movement (direction and relative speed)
 Behavior (logging [resting at the surface], swimming, 
spyhopping [raising above the water surface to view the area], 
foraging, etc.)
 Duration of sighting or times of multiple sightings of the 
same individual
(5) Real Time Acoustic Monitoring for Harbor Porpoises
    While harbor porpoises are not expected to be within the CALTRANS' 
Pier E3 implosion Level B TTS ZOI (within 26,500 ft [8,077 ms]) in 
November, real time acoustic monitoring to confirm species absence 
shallow be implemented as an added measure in addition to active 
monitoring by trained visual PSOs. Harbor porpoises vocalize frequently 
with other animals within their group, and use echolocation to navigate 
and to locate prey. Therefore, as an additional monitoring tool, a real 
time acoustic monitoring system will be used to detect the presence or 
absence of harbor porpoises as a supplement to visual monitoring.
    The system would involve two bio-acousticians monitoring the site 
in real time, likely near the north end of Treasure Island as most 
harbor porpoises appear to pass through the area north of Treasure 
Island before heading south toward the East Span of the SFOBB. A 
calibrated hydrophone or towed array would be suspended from a boat 
and/or several sonobuoys (acoustic information is sent via telemetry to 
the acoustic boat) or a hydrophone moored offshore with a cable leading 
to a shore based acoustic station will be deployed outside of the 
monitoring area of Pier E3. All equipment will be calibrated and tested 
prior to the implosion to ensure functionality. This system would not 
be able to give an accurate distance to the animal but would either 
determine that no cetaceans are in the area or would provide a relative 
distance and direction so that PSOs could search for the cetaceans and 
determine if those animals have entered or may enter the Pier E3 
implosion area. The bio-acousticians would be in communication with the 
Lead PSO and would alert the crew to the presence of any cetacean 
approaching the monitoring area. It would also provide further 
confirmation that there are no cetaceans around Pier E3 in addition to 
the visual observations documenting no observations.
(6) Hydroacoustic Monitoring for Underwater Implosion
    The purpose of hydroacoustic monitoring during the controlled 
implosion of Pier E3 is twofold: (1) To evaluate distances to marine 
mammal impact noise criteria; and (2) to improve the prediction of 
underwater noise for assessing the impact of the demolition of the 
remaining piers through future controlled implosions.
    Monitoring of the implosion is specific to two regions around Pier 
E3 with unique methods, approaches, and plans for each of these 
regions. These regions include the ``near field'' and the ``far 
field''. For Pier E3, the near field will comprise measurements taken 
within 500 ft of the pier while the far field will comprise 
measurements taken at 500 feet and all greater distances.
    Measurements inside the BAS will be made with near and far field 
systems using PCB 138A01 transducers. At the 100-ft distance, the near 
field system will use another PCB 138A01 transducer while the far field 
system will use both a PCB 138A01 transducer and a Reson TC4013 
hydrophone. Prior to activating the BAS, ambient noise levels will be 
measured. While the BAS is operating and before the test implosion, 
background noise measurements will also be made. After the test 
implosion, the results will be evaluated to determine if any final 
adjustments are needed in the measurement systems prior to the Pier E3 
controlled implosion. Pressure signals will be analyzed for peak 
pressure and SEL values prior to the scheduled time of the Pire E3 
controlled implosion.

Reporting Measures

    CALTRANS is required to submit a draft monitoring report within 90 
days after completion of the construction work or the expiration of the 
IHA, whichever comes earlier. This draft report would detail the 
monitoring protocol, summarize the data recorded during monitoring, and 
estimate the number of marine mammals that may have been harassed. NMFS 
would have an opportunity to provide comments on the draft report 
within 30 days, and if NMFS has comments, CALTRANS would address the 
comments and submit a final report to NMFS within 30 days. If no 
comments are provided by NMFS after 30 days receiving the report, the 
draft report is considered to be final.

Marine Mammal Stranding Plan

    In addition, a stranding plan will be prepared in cooperation with 
the local NMFS-designated marine mammal stranding, rescue, and 
rehabilitation center. Although mitigation measures would likely 
prevent any injuries, preparations will be made in the unlikely event 
that marine mammals are injured. Elements of that plan would include 
the following:
    1. The stranding crew would prepare treatment areas at the NMFS-
designated facility for cetaceans or pinnipeds that

[[Page 57590]]

may be injured from the implosion. Preparation would include equipment 
to treat lung injuries, auditory testing equipment, dry and wet caged 
areas to hold animals, and operating rooms if surgical procedures are 
necessary. Equipment to conduct auditory brainstem response hearing 
testing would be available to determine if any inner ear threshold 
shifts (TTS or PTS) have occurred (Thorson et al. 1999).
    2. A stranding crew and a veterinarian would be on call near the 
Pier E3 site at the time of the implosion to quickly recover any 
injured marine mammals, provide emergency veterinary care, stabilize 
the animal's condition, and transport individuals to the NMFS-
designated facility. If an injured or dead animal is found, NMFS (both 
the regional office and headquarters) will be notified immediately even 
if the animal appears to be sick or injured from other than blasting.
    3. Post-implosion surveys would be conducted immediately after the 
event and over the following three days to determine if there are any 
injured or dead marine mammals in the area.
    4. Any veterinarian procedures, euthanasia, rehabilitation 
decisions and time of release or disposition of the animal will be at 
the discretion of the NMFS-designated facility staff and the 
veterinarians treating the animals. Any necropsies to determine if the 
injuries or death of an animal was the result of the blast or other 
anthropogenic or natural causes will be conducted at the NMFS-
designated facility by the stranding crew and veterinarians. The 
results will be communicated to both CALTRANS and to NMFS as soon as 
possible with a written report within a month.

Estimated Take by Incidental Harassment

    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].
    Numbers of marine mammals within the Bay may be incidentally taken 
during demolition using controlled charges (impulse sound) related to 
the demolition of the original East Span of the SFOBB were calculated 
based on acoustic propagation models for each functional hearing group 
and the estimated density of each species in the project vicinity. 
Specifically, the takes estimates are calculated by multiplying the 
ensonified areas that are specific to each functional hearing group by 
the density of the marine mammal species.

Marine Mammal Density Estimates

    There are no systematic line transect surveys of marine mammals 
within San Francisco Bay, therefore, the in water densities of harbor 
seals, California sea lions, and harbor porpoises were calculated from 
14 years of observations during monitoring for the SFOBB construction 
and demolition. During the 210 days of monitoring (including 15 days of 
baseline monitoring in 2003), 657 harbor seals, 69 California sea lions 
and three harbor porpoises were observed within the waters of the east 
span of the SFOBB. Density estimates for other species were made from 
stranding data provided by the MMC (Sausalito, CA; Northern elephant 
seal).
(1) Pacific Harbor Seal
    Most data on harbor seal populations are collected while the seals 
are hauled out. This is because it is much easier to count individuals 
when they are out of the water. In-water density estimates rely on 
haul-out counts, the percentage of seals not on shore based on radio 
telemetry studies, and the size of the foraging range of the 
population. Harbor seal density 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, 
outside of the Pier E3 hydroacoustic zone) in February 2014, very few 
harbor seals were observed foraging near Yerba Buena Island (YBI) or 
transiting through the SFOBB area for approximately two weeks. 
Sightings went from a high of 16 harbor seal individuals foraging or in 
transit in one day to 0-2 seals per day in transit or foraging through 
the SFOBB area (CALTRANS 2014). Calculated harbor seal density is a per 
day estimate of harbor seals in a 1 km\2\ area within the fall/winter 
or spring/summer seasons.
    Harbor seal density for the proposed project was calculated from 
all observations during SFOBB Project monitoring from 2000 to 2014. 
These observations included data from baseline, pre, during and post 
pile driving and onshore implosion activities. During this time, the 
population of harbor seals within the Bay has remained stable (Manugian 
2013), therefore, we do not anticipate significant differences in 
numbers or behaviors of seals hauling out, foraging or in their 
movements over that 15 year period. All harbor seal observations within 
a km\2\ area were used in the estimate. Distances were recorded using a 
laser range finder (Bushnell Yardage Pro Elite 1500; 1.0 
yards accuracy). Care was taken to eliminate multiple observations of 
the same animal although this was difficult when more than three seals 
were foraging in the same area.
    Density of harbor seals was highest near YBI and Treasure Island, 
probably due to the haul-out site and nearby foraging areas in the 
Coast Guard and Clipper coves. Therefore, density estimates were 
calculated for a higher density area within 3,936 ft (1,200 m) west of 
Pier E3, which includes these two foraging coves. A lower density 
estimate was calculated from the area east of Pier E3 and beyond 3,936 
ft (1,200 m) to the north and south of Pier E3.
    These density estimates were then extrapolated to the threshold 
criteria areas delineated by the hydroacoustic models to calculate the 
number of harbor seals likely to be exposed.
(2) California Sea Lion
    Most data on California sea lion populations are collected while 
the seals are hauled out as it is much easier to count individuals when 
they are out of the water. In-water density estimates rely on haul-out 
counts, the percentage of sea lions not on shore based on radio 
telemetry studies, and the size of the foraging range of the 
population. Sea lion density, like harbor seal densities, in the water 
can vary greatly depending on weather conditions, the availability of 
prey, and the season. For example, sea lion density increases during 
the summer and fall after the end of the breeding season at the 
Southern California rookeries.
    For the proposed project, California sea lion density was 
calculated from all observations during SFOBB monitoring from 2000 to 
2014. These observations included data from baseline, pre, during and 
post pile driving and onshore implosion activities. During this time, 
the population of sea lions within the Bay has remained stable as have 
the numbers observed near the SFOBB (Manugian 2013). As a result, we do 
not anticipate significant differences in the number of sea lion or 
their movements over that 15 year period. All sea lion observations 
within a km\2\ area were used in the estimate. Distances were recorded 
using a laser range finder (Bushnell Yardage Pro Elite 1500; 1.0 yards accuracy). Care was taken to eliminate multiple 
observations of the same animal, although most sea lion observations 
involve a single animal.

[[Page 57591]]

Calculated California sea lion density is a per day estimate of sea 
lions in a one km\2\ area within the fall/winter or spring/summer 
seasons.
(3) Northern Elephant Seal
    Northern elephant seal density around Pier E3 was calculated from 
the stranding records of the MMC from 2004 to 2014. These data included 
both injured or sick seals and healthy seals. Approximately 100 
elephant seals were reported within the Bay during this time, most of 
these hauled out and were likely sick or starving. The actual number of 
individuals within the Bay may be higher as not all individuals would 
necessarily have hauled out. Some individuals may have simply left the 
Bay soon after entering. Data from the MMC show several elephant seals 
stranding on Treasure Island and one healthy elephant seal was observed 
resting on the beach in Clipper Cove in 2012. Elephant seal pups or 
juveniles also may strand after weaning in the spring and when they 
return to California in the fall (September through November).
(4) Harbor Porpoise
    Harbor porpoise density was calculated from all observations during 
SFOBB monitoring from 2000 to 2014. These observations included data 
from baseline, pre, during and post pile driving and onshore implosion 
activities. Over this period, the number of harbor porpoises that were 
observed entering and using the Bay increased. During the fifteen years 
of observational data around the SFOBB Project, only four harbor 
porpoises were observed and all occurred from 2006 to 2014 (including 
two in 2014). All harbor porpoise observations within a km\2\ area were 
used in the estimate. Distances were recorded using a laser range 
finder (Bushnell Yardage Pro Elite 1500; 1.0 yards 
accuracy).
    A summary of marine mammal density information is provided in Table 
5.

 Table 5--Estimated In-Water Density of Marine Mammals That May Occur in the Vicinity of CALTRANS' Proposed Pier
                                          E3 Controlled Implosion Area
----------------------------------------------------------------------------------------------------------------
                                   Main season of       Density within 1,200m of      Density beyond 1,200m of
            Species                   occurence          SFOBB (animals/km\2\)          SFOBB (animals/km\2\)
----------------------------------------------------------------------------------------------------------------
Pacific Harbor Seal............  Spring-Summer       0.30.........................  0.15.
                                  (pupping/molt
                                  seasons).
Pacific Harbor Seal............  Fall-Winter.......  0.77.........................  0.15.
Sea Lion.......................  Late Summer-Fall    0.12.........................  0.12.
                                  (Post Breeding
                                  Season).
Sea Lion.......................  Late Spring-Early   0.06.........................  0.06.
                                  Summer (Breeding
                                  Season).
Northern Elephant Seal.........  Late Spring-Early   0.03.........................  0.03.
                                  Winter (Pups
                                  After First Trip
                                  To Sea).
Harbor Propoise................  All Year..........  Very Low, estimated at 0.004.  Very Low, estimated at
                                                                                     0.004.
----------------------------------------------------------------------------------------------------------------

Impact Zones Modeling

    Since the proposed Pier E3 controlled implosion would be carried as 
a confined explosion, certain elements were taken into the modeling 
process beyond a simple open-water blast model. Confinement is a 
concept in blasting that predicts the amount of blast energy that is 
expected to be absorbed by the surrounding structural material, 
resulting in the fracturing necessary for demolition. The energy beyond 
that absorbed by the material is the energy that produces the pressure 
wave propagating away from the source. NMFS has determined that 
modeling with confinement was appropriate for the proposed Pier E3 
blast by evaluating blast results from case study data for underwater 
implosions similar to the SFOBB Pier E3 implosion. In addition, the 
NMFS worked with CALTRANS and compared case study results to published 
blast models that incorporate a degree of confinement.
    Data from 39 comparable underwater concrete blasts were used by 
CALTRANS to evaluate potential equations for modeling blast-induced 
peak pressures and subsequent effects to marine mammals (Kiewit-Mason, 
pers. Comm 2015 in CALTRANS 2015). All 39 blasts occurred in 
approximately 55 ft (16.8 m) of water, similar to the maximum water 
depth around Pier E3. In addition, all blasts had burdens (i.e., 
distance from the charge to the outside side of the material being 
fractured) of approximately 1.5 to 2 ft (0.5 to 0.6 m). Burdens for 
Pier E3 also are estimated to be in this range. Data provided included 
the charge weight, observed peak pressure, distance of peak pressure 
observation, and the modeled peak pressure using Cole's confined 
equation, Cole's unconfined equation, and Oriard's conservative 
concrete equation (Cole 1948; Oriard 2002).
    Using these data, appropriate equations for modeling the associated 
hydroacoustic impacts are established for the Pier E3 controlled 
implosion. Cole's unconfined equation greatly overestimated peak 
pressures for all blasts while Cole's confined equation appeared to 
most accurately predict observed peak pressures. Oriard's conservative 
concrete equation overestimated peak pressures, but not as dramatically 
as under Cole's unconfined equation. NMFS and CALTRANS have opted to 
use more conservative methods to ensure an additional level of safety 
when predicting the monitoring zone and potential impact areas to 
marine mammals from the proposed controlled implosion project.
    The applicable metrics discussed are the peak pressure 
(Ppk) expressed in dB, the accumulated sound exposure level 
(SEL) also expressed in dB, and the positive acoustic impulse (I) in 
Pa-sec. The criteria for marine mammals are grouped into behavioral 
response, slight injury, mortality, and the specific acoustic 
thresholds depend on group and species. These are summarized in Table 
2. The metrics for these are criteria defined as:

[[Page 57592]]

[GRAPHIC] [TIFF OMITTED] TN24SE15.000

General Assumptions

    The blast event will consist of a total of 588 individual delays of 
varying charge weight; the largest is 35 pounds/delay and the smallest 
is 21 pounds/delay. The blasting sequence is rather complex. On the 
full height walls, 30 pound weights will be used for the portion below 
mud line, 35 pound weights will be used in the lower structure 
immediately above mud line, 29.6 pounds in the midstructure, and 21 
pounds in the upper structure. Full details on the delay weights and 
locations can be found in the Blast Plan (CALTRANS 2015). Blasts will 
start in several interior webs of the southern portion of the structure 
followed by the outer walls of the south side. The blasts in the inner 
walls will occur just prior to the adjacent outer walls. The interior 
first, exterior second blast sequence will continue across the 
structure moving from south to north. The time for the 588 detonations 
is 5.3 seconds with a minimum delay time of 9 milliseconds (ms) between 
detonations. As the blasting progresses, locations to east, north, and 
west of the pier will be shielded from the blasting on the interior of 
the structure from the still-standing exterior walls of the pier. 
However, towards the conclusion of the blast, each direction will 
experience blasts from the outer walls that are not shielded.
    To estimate Ppk and P\2\(t), several assumptions were 
made. For simplification, it was assumed that there is only one blast 
distance and it is to the closest point on the pier from the receiver 
point. In actuality for almost all explosions, distances from the blast 
will be greater as the pier is approximately 135 ft (41 m) across and 
80 ft (24 m) wide. Based on these dimensions, the actual blast point 
could be up to 135 ft (41 m) further from the receptor point used for 
the calculation. As a result, the calculated peak level is the maximum 
expected for one 35 pound blast while the other levels would be lower 
depending on the distance from the actual blast location to the 
calculation point and weight of the charge. In other words, the 
pressure received at the calculation point would not be 588 signals of 
the same amplitude, but would be from one at the estimated level for a 
35 pound charge and 587 of varying lower amplitudes. Similarly, in the 
vertical direction, the location varies over a height of about 50 ft 
(15 m) and those blasts that are not at the same depth as the receiver 
would also be lower. This effect of variation in assumed blast to 
receiver distance will be most pronounced close to the pier, while at 
distances of about 1,000 ft (305 m) or greater, the effect would be 
less than 1 dB.
    In the calculations, it was also assumed that there would be no 
self-shielding of the pier as the explosions progress. From the above 
discussion of the blast sequence, some shielding of the blasts along 
the interior of the pier will occur. However, the blasts that occur in 
outer wall (towards the end of the implosion) will not be shielded for 
all blasts. A blast in the outer wall that has a direct line of sight 
to the receptor calculation point will not be shielded and will 
generate the highest peak

[[Page 57593]]

pressure relative to be compared to the Lpk criterion. The 
cumulative SEL and the root-mean-squared (RMS) levels; however, will be 
reduced to some degree by the outer walls until they are demolished as 
these metrics are defined by the pressure received throughout the 
entire 5.3 second event. However, due to the complexity of the blast 
sequence, this shielding effect was not considered in the calculated 
SEL and RMS levels.
    Based on the Blast Plan (CALTRANS 2015), the delays are to be 
placed in 2\3/4\ to 3 inch (7 to 7.6 cm) diameter holes drilled into 
the concrete pier structure. The outer walls of the pier are nominally 
3 ft-11\1/2\ inch (1.5 m) thick and inner walls are nominally 3 ft (0.9 
m) thick. Individual blasts should be not exposed to open water and 
some confinement of the blasts is expected. For confined blasts, the 
predicted pressures can be reduced by 65 to 95% (Nedwell and 
Thandavamoorthy 1992; Rickman 2000; Oriard 2002; Rivey 2011), 
corresponding to multiplication factors from 0.35 to 0.05, 
respectively. Based on a review of the available literature and recent 
data from similar explosive projects, CALTRANS and NMFS decided to use 
a conservative confinement factor of K=7500 which equates to a 65% 
reduction in pressure and by a multiplication factor of 0.3472 (Eq. 4).
    Another assumption was to consider only the direct wave from an 
individual blast. In shallow water, the signal at the receiver point 
could consist of the direct wave, surface-relief wave generated by the 
water/air interface, a reflected wave from the bottom, and a wave 
transmitted through the bottom material (USACE 1991). For estimating 
Ppk, only the direct wave is considered as it will have the highest 
magnitude and will arrive at the receiver location before any other 
wave component. However, P(t) after the arrival of the direct wave peak 
pressure will be effected. The surface-relief wave is negative so that 
when it arrives at the receiver location, it will reduce the positive 
pressure of the direct wave and can make the total pressure negative at 
times after the arrival of the initial positive peak pressure. Since 
the SEL is a pressure squared quantity, any negative pressure can also 
contribute to the SEL. However, the amplitude and arrival time of the 
surface-relief wave depends on the geometry of the propagation case, 
that is, depth of water, depth of blast, and distance and depth of the 
receiver point. The effect of this assumption is discussed further in 
the section on SEL.

Estimation of Peak Pressure

    Peak pressures were estimated by following the modified version of 
the Cole Equation for prediction of blasts in open, deep water (Cole 
1948). The peak pressure is determined by:
[GRAPHIC] [TIFF OMITTED] TN24SE15.001

where Ppk is peak pressure in pounds per square inch (psi), and 
[lambda] is the scaled range given by R/W1/3 in which R is the distance 
in feet and W is the weight of the explosive charge in pounds. A 
modified version of the Cole Equation has been documented in U.S. Army 
Corps of Engineer (USACE) Technical Letter No. 1110-8-11(FR) and is 
applicable to shallow water cases such as that of the Pier E3 
demolition (USACE 1991). The constant K factor multiplier in the USACE 
calculation is 21,600 for an open-water blast instead of the 22,550 
from the original Cole Expression. This factor is slightly less (~4%) 
than the original Cole. The decay factor (-1.13) used in the USACE 
modified equation remains the same as the original Cole Equation. To 
account for the confining effect of the concrete pier structure, a 
conservative K factor of 7,500 was used corresponding to multiplying 
USACE Ppk by a factor of 0.3472. With a minimum delay between of blast 
of 9 ms, the individual delays will be spaced sufficiently far in time 
to avoid addition of the peak pressures. In this case, the peak 
pressure is defined by that calculated for the largest charge weight of 
35 pounds/delay. A BAS is specified in the Blast Plan. Based on the 
literature and recent results from similar projects, reductions in the 
pressure peak of 85% to 90% or more are expected. For determining Ppk 
in this analysis, a conservative reduction of 80% has been used. Based 
on values of confinement, BAS performance, and the ``General 
Assumptions'' above, the calculated peak pressures are expected to be 
conservative.

Estimation of SEL Values

    Estimating the weighted SEL values for the different groups/species 
is a multiple step process. The first step is to estimate SEL values as 
a function of distance from the blast pressure versus time histories 
for each of the six charge weights as a function of distance. The open-
water equation used for this calculation was that modified by the USACE 
(1991) based on methods pioneered by Cole (1948). Pressure as a 
function of time is given by:
[GRAPHIC] [TIFF OMITTED] TN24SE15.002

where ta is given as R/5,000 and [thgr] is:
[GRAPHIC] [TIFF OMITTED] TN24SE15.003

    These calculations were then extended to distances out to 160,000 
ft (48.8 km).
    As discussed previously, there are other wave components that could 
be considered in the SEL estimation, including the surface relief wave, 
reflection from the bottom, and transmission through and re-radiation 
from the bottom. Little or no contribution is expected from the bottom 
based on its sedimentary nature and previous experiences from measuring 
noise from underwater pile driving in the area around Pier E3. The

[[Page 57594]]

negative surface relief wave could be a factor in the SEL estimation. 
This wave could either increase or decrease the SEL depending on its 
arrival time relative to the direct wave. For small differences in 
arrival time, the surface relief will decrease the total SEL as a 
portion of the positive direct wave is negated by the addition of the 
negative surface relief wave. For closer distances and when the 
receptor and blast locations are near the bottom, the total SEL can 
become greater than the direct wave SEL, but only by less than 3 dB. 
However, whenever the source or receiver is near the surface, the 
direct wave SEL will be greater than the total SEL and can approach 
being 10 dB greater for distances beyond 1,000 ft (305 m). As a result, 
the surface relief wave is ignored in this analysis knowing that the 
surface relief wave would only tend to produce lower SEL values than 
the direct wave.
    For each of the marine mammal groupings included in Table 2, 
specific filter shapes apply to each functional hearing group. To apply 
this weighting, the Fast Fourier Transform (FFT) was calculated for the 
time histories at each analysis distance. Each FFT was then filtered 
using the frequency weighted specified for each group. Filter factors 
were then determined for each distance by subtracting the filtered 
result from the unfiltered FFT data and determining the overall noise 
reduction in decibels. These filter factors were applied to the 
accumulated SEL determined for the entire blast event for each distance 
from the Pier.
    The BAS of the Blast Plan will have an effect on the wave once a 
blast passes through it. In a research report by USACE in 1964, the 
performance of a BAS was examined in detail (USACE 1964). It has also 
been found that for an energy metric such as SEL, the reduction 
produced by the BAS was equal to or greater than the reduction of the 
peak pressure (USACE 1991; Rude 2002; Rude and Lee 2007; Rivey 2011). 
To estimate the reduction for SEL values due to the BAS installed in 
the Blast Plan (CALTRANS 2015), SEL was reduced by 80%. Effectively, 
this was done by reducing the SEL by 20 Log (0.20), or 14 dB. Delays 
below the mudline, which will be located below the BAS, were also 
reduced by 80% based on an assumption that the outside pier walls here 
(which will not be removed) and Bay mud sediments will provide a 
similar level of attenuation. These SEL values and those without the 
BAS were then compared to the appropriate criteria for each marine 
mammal group. Because the calculation of SEL is based on the peak 
pressure, these estimates for the direct wave component are expected to 
be conservative for the same reasons as described for the peak 
pressures.

Estimation of Positive Impulse

    To estimate positive impulse values, the expression originally 
developed by Cole for open water was used (Cole 1948). This expression 
includes only contributions from the direct wave neglecting any 
contribution from the surface relief, bottom reflected, and bottom 
transmitted consistent with the assumptions used to estimate SEL. In 
this case, impulse is given by:
[GRAPHIC] [TIFF OMITTED] TN24SE15.004

with the variables defined in Equation 4. The impulse can also 
equivalently be calculated from wave forms. Equation 5 produces impulse 
values in psi-msec which were converted to Pa-sec by multiplying by 6.9 
for comparison to the marine mammal criteria.
    Unlike Ppk and SEL, no reduction by the BAS is assumed for the 
impulse calculation. The area under the P(t) curve under goes little 
change after passing the BAS. The peak pressure is reduced as noted 
previously, however, since the P(t) expands in duration, the area 
change is minimal. This behavior is well documented in the literature 
(Cole 1948; USACE 1964; USACE 1991; Rickman 2000). As discussed above, 
this is not the case for SEL which is determined by the area under the 
P\2\(t) curve.

Estimated Takes of Marine Mammals

    The estimated distances (Table 3) to the marine mammal criteria for 
peak pressure, SEL, and impulse are based on established relationships 
between charge weight and distance from the literature. The estimated 
distances were determined assuming unconfined open water blasts from 
the original Cole equations or the Cole equations modified by USACE. 
The assumption of open water neglects several effects that could 
produce lower levels than estimated. These include no shielding by the 
pier structure prior a specific blast, confining of the individual 
delays in the holes drilled into the pier structure, and longer 
distances to individual blasts than assumed by closest distance between 
the pier and the receptor point. For SEL, the assumption of open water 
blasts neglects the surface relief wave which at longer distances from 
the pier, would tend to reduce the SEL due to interference with the 
direct wave. Although the estimated levels and distances may be 
conservative, there is sufficient uncertainty in the blast event and 
its propagation such that further, less conservative adjustments would 
not be appropriate.
    Estimated exposure numbers are subsequently calculated based on 
modeled ensonified areas and marine mammal density information. 
However, since many marine mammals are expected to occur in groups, the 
estimated exposure numbers are adjusted upward by a factor of 2 to 
provide estimated take numbers. In addition, although modeling shows 
that no California sea lion would be exposure to noise levels that 
would result in a take, its presence in the vicinity of SFOBB has been 
documented. Therefore, take of 2 of California sea lion is assessed. A 
summary of estimated takes and exposures of marine mammals that could 
result from CALTRANS' Pier E3 controlled implosion is provided in Table 
6.

[[Page 57595]]



                    Table 6--Summary of the Estimated Takes and Exposures (in Parenthesis) of Marine Mammals to the Pier E3 Implosion
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                   Level B take
                         Species                         --------------------------------  Level A take      Mortality      Population        % take
                                                            Behavioral          TTS                                                         population
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pacific harbor seal.....................................          12 (6)           6 (3)           0 (0)           0 (0)          30.196            0.06
California sea lion.....................................           2 (0)           0 (0)           0 (0)           0 (0)         296,750            0.00
Northern elephant seal..................................           2 (1)           0 (0)           0 (0)           0 (0)         124,000            0.00
Harbor porpoise.........................................           2 (1)           0 (0)           0 (0)           0 (0)           9,886            0.02
--------------------------------------------------------------------------------------------------------------------------------------------------------

Analysis and Determinations

Negligible Impact

    Negligible impact is ``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 Level B harassment 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 behavioral harassment, 
NMFS must consider other factors, such as the likely nature of any 
responses (their intensity, duration, etc.), the context of any 
responses (critical reproductive time or location, migration, etc.), as 
well as the number and nature of estimated Level A harassment takes, 
the number of estimated mortalities, and effects on habitat.
    To avoid repetition, this introductory discussion of our analyses 
applies to all the species listed in Table 5, given that the 
anticipated effects of CALTRANS' Pier E3 controlled implosion on marine 
mammals are expected to be relatively similar in nature. There is no 
information about the nature or severity of the impacts, or the size, 
status, or structure of any species or stock that would lead to a 
different analysis for this activity.
    No injuries or mortalities are anticipated to occur as a result of 
CALTRANS' controlled implosion to demolish Pier E3, and none are 
authorized. The relatively low marine mammal density and small Level A 
exclusion zones make injury takes of marine mammals unlikely, based on 
take calculation described above. In addition, the Level A exclusion 
zones would be thoroughly monitored before the proposed implosion, and 
detonation activity would be postponed if an marine mammal is sighted 
within the exclusion.
    The takes that are anticipated and authorized are expected to be 
limited to short-term Level B harassment (behavioral and TTS). Marine 
mammals (Pacific harbor seal, northern elephant seal, California sea 
lion, and harbor porpoise) present in the vicinity of the action area 
and taken by Level B harassment would most likely show overt brief 
disturbance (startle reaction) and avoidance of the area from the 
implosion noise. A few Pacific harbor seals could experience TTS if 
they occur within the Level B TTS ZOI. 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. In 
addition, even if an animal receives a TTS, the TTS would just be a 
one-time event from a brief impulse noise (about 5 seconds), making it 
unlikely that the TTS would evolve into PTS. Finally, there is no 
critical habitat and other biologically important areas in the vicinity 
of CALTRANS' proposed Pier E3 controlled implosion area (John 
Calambokidis et al. 2015).
    The project also is not expected to have significant adverse 
effects on affected marine mammals' habitat, as analyzed in detail in 
the ``Anticipated Effects on Marine Mammal Habitat'' section. The 
project activities would not modify existing marine mammal habitat. The 
activities may kill some fish and cause other fish to leave the area 
temporarily, thus impacting marine mammals' foraging opportunities in a 
limited portion of the foraging range; but, because of the short 
duration of the activities and the relatively small area of the habitat 
that may be affected, the impacts to marine mammal habitat are not 
expected to cause significant or long-term negative consequences.
    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 prescribed monitoring and 
mitigation measures, NMFS finds that the total marine mammal take from 
CALTRANS's Pier E3 demolition via controlled implosion will not 
adversely affect annual rates of recruitment or survival; accordingly 
we conclude the taking will have a negligible impact on the affected 
marine mammal species or stocks.

Small Numbers

    The requested takes represent less than 0.06% of all populations or 
stocks potentially impacted (see Table 6 in this document). These take 
estimates represent the percentage of each species or stock that could 
be taken by Level B behavioral harassment and TTS (Level B harassment). 
The numbers of marine mammals estimated to be taken are small 
proportions of the total populations of the affected species or stocks. 
In addition, the mitigation and monitoring measures (described 
previously in this document) prescribed in the IHA are expected to 
reduce even further any potential disturbance to marine mammals.
    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 mitigation and monitoring 
measures, NMFS finds that small numbers of marine mammals will be taken 
relative to the populations of the affected species or stocks.

Impact on Availability of Affected Species for Taking for Subsistence 
Uses

    There are no subsistence uses of marine mammals in the project 
area; and, thus, no subsistence uses impacted by this action. 
Therefore, NMFS has determined that the total taking of affected 
species or stocks would not have an unmitigable adverse impact on the 
availability of such species or stocks for taking for subsistence 
purposes.

Endangered Species Act (ESA)

    NMFS has determined that issuance of the IHA will have no effect on 
listed marine mammals, as none are known to occur in the action area.

[[Page 57596]]

National Environmental Policy Act (NEPA)

    NMFS prepared an Environmental Assessment (EA) and a Supplemental 
Environmental Assessment (SEA) for the take of marine mammals 
incidental to construction of the East Span of the SF-OBB and made 
Findings of No Significant Impact (FONSIs) on November 4, 2003 and 
August 5, 2009. Due to the modification of part of the demolition of 
the original SFOBB using controlled implosion and the associated 
mitigation and monitoring measures, NMFS prepared an SEA and analyzed 
the potential impacts to marine mammals that would result from the 
modification. A Finding of No Significant Impact (FONSI) was signed in 
September 2015. A copy of the EA and FONSI is available upon request 
(see ADDRESSES).

Authorization

    NMFS has issued an IHA to CALTRANS for the potential harassment of 
small numbers of four marine mammal species incidental to the SFOBB 
Pier E3 demolition via controlled implosion in San Francisco Bay, 
provided the previously mentioned mitigation, monitoring, and reporting 
requirements are incorporated.

    Dated: September 18, 2015.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2015-24230 Filed 9-23-15; 8:45 am]
BILLING CODE 3510-22-P