[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
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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.
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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
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Level B harassment Level A Serious injury
---------------------------------- harassment ------------------------------------
Group Species ------------------ Gastro- Mortality
Behavioral TTS PTS intestinal tract Lung
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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.
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* 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
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Level B criteria Level A criteria
Species ----------------------------------------------------------------------------------------------------- Mortality
Behavioral response TTS Dual criteria PTS Dual criteria GI track Lung injury
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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)...........
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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
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Species Level B TTS
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Pacific harbor seal........................ 45 feet.
California sea lion........................ 45 feet.
Northern elephant seal..................... 45 feet.
Harbor porpoise............................ 270 feet.
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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