[Federal Register Volume 68, Number 220 (Friday, November 14, 2003)]
[Notices]
[Pages 64595-64609]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-28549]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[I.D. 110801C]


Taking of Marine Mammals Incidental to Specified Activities; 
Construction of the East Span of the San Francisco-Oakland Bay Bridge

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

ACTION: Notice of issuance of an incidental harassment authorization.

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SUMMARY: In accordance with provisions of the Marine Mammal Protection 
Act (MMPA) as amended, notification is hereby given that an Incidental 
Harassment Authorization (IHA) has been issued to the California 
Department of Transportation (CALTRANS) to take small numbers of 
California sea lions, Pacific harbor seals, and gray whales, by 
harassment, incidental to construction of a replacement bridge for the 
East Span of the San Francisco-Oakland Bay Bridge (SF-OBB) in 
California.

DATES: This authorization is effective from November 10, 2003, through 
November 9, 2004.

ADDRESSES: A copy of the application and/or a list of references used 
in this document may be obtained by writing to the Chief, Marine Mammal 
Conservation Division, Office of Protected Resources, NMFS, 1315 East-
West Highway, Silver Spring, MD 20910-3225, or by telephoning one of 
the contacts listed here.

FOR FURTHER INFORMATION CONTACT: Kenneth Hollingshead, NMFS, (301) 713-
2322, ext 128.

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, notice of a proposed authorization is 
provided to the public for review.
    Permission may be granted if NMFS finds that the taking will have 
no more than a negligible impact on the species or stock(s) and will 
not have an unmitigable adverse impact on the availability of the 
species or stock(s) for subsistence uses and that the permissible 
methods of taking and requirements pertaining to the monitoring and 
reporting of such taking 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 United States can apply for an authorization 
to incidentally take small numbers of marine mammals by harassment. 
Under section 18(A), 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

[[Page 64596]]

disruption of behavioral patterns, including, but not limited to, 
migration, breathing, nursing, breeding, feeding, or sheltering 
[Level B harassment].
    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 
small numbers of marine mammals. Within 45 days of the close of the 
comment period, NMFS must either issue or deny issuance of the 
authorization.

Summary of Request

    On September 14, 2001, NMFS received a request from CALTRANS 
requesting an IHA for the possible harassment of small numbers of 
California sea lions (Zalophus californianus), Pacific harbor seals 
(Phoca vitulina richardsii), and gray whales (Eschrichtius robustus) 
incidental to construction of a replacement bridge for the East Span of 
the SF-OBB, in San Francisco Bay (SFB, or the Bay), California.

Project Description

    The SF-OBB is an important transportation component of the Bay area 
that provides regional access between the San Francisco Peninsula and 
the East Bay. An average of 272,000 vehicles currently use the SF-OBB, 
a part of Interstate 80, each day. The East Span Project will provide a 
seismically upgraded vehicular crossing for current and future users. 
The existing East Span must be replaced or retrofitted because it is 
not expected to withstand a maximum credible earthquake on the San 
Andreas (Richter 8) or Hayward (Richter 7.25) faults, it does not meet 
lifeline criteria for providing emergency relief access following a 
maximum credible earthquake, and it does not meet current operational 
and safety design standards.
    The new bridge will be constructed north of the existing East Span 
and will be approximately 3,514 meters (m) (2.18 mi) long and 
approximately 70 m (230 ft) wide, including a 15.3 m (50 ft) minimum 
space between the east and westbound bridge decks. The bridge decks 
will be side-by-side, except for the double deck portion between the 
existing Yerba Buena Island (YBI) tunnel and the transition structures 
where the double deck structure becomes two parallel structures. Each 
deck will consist of five traffic lanes and inside and outside 
shoulders and a bicycle/pedestrian path will be constructed on the 
south side of the eastbound structure. The East Span Project would also 
replace the eastbound on-ramp on YBI. The existing ramp needs to be 
dismantled to construct the new bridge. The ramp would be rebuilt and 
would meet current design and safety standards.
    The foundations for the piers of the replacement East Span will 
consist of large diameter steel pipe piles that will be driven into the 
Bay floor. Current plans anticipate driving a total of 189 2.5 m (8.2 
ft) diameter piles and 70 1.8 m (5.9 ft) diameter steel pipe piles. 
Each pile is expected to consist of two or more segments; the first 
segment will be driven to an established depth, then the next 
segment(s) will be welded on and driven in succession until the pile is 
driven to its final or ``tip'' depth (or elevation). However, the 
contractor could choose to drive the piles in one piece. Some piles 
will be battered, meaning that they will be driven in at an angle, 
essentially splaying out from the pier to provide additional stability. 
The rest would be vertical piles. The larger piles will support the 
skyway and main span sections of the replacement bridge; they will be 
driven to depths ranging from about -66 m to about -108 m (-256 ft to -
358 ft), with most being driven to about -95 m (-312 ft). The smaller 
diameter piles will support the Oakland Touchdown structures; they will 
be driven to ``tip'' depth ranging from about -41 m to about -65 m (-
135 ft to 213 ft).
    Due to the untested nature of large hammers and piles in SFB, a 
pile installation demonstration was conducted in the central SFB 
between October 23 and December 12, 2000, to evaluate engineering and 
environmental factors associated with installing large steel piles to 
support the replacement East Span. The Pile Installation Demonstration 
Project (PIDP) involved driving three steel piles, using two types of 
hydraulic hammers, one with a maximum energy rating of 500 kilojoules 
(kJ) and one with a maximum rating of 1,700 kJ. Each pile had four 
segments, which were welded together on site. In addition to driving 
one pile without the use of any sound attenuation devices, the PIDP 
tested two different types of in-water sound attenuating equipment: (1) 
An air bubble curtain (using approximately 1.6 cubic-feet-per minute 
per linear foot of air flow) and (2) a proprietary fabric barrier 
system with an aerating mechanism. The PIDP was conducted to 
investigate construction requirements, identify potential problems, 
make modifications to equipment, and examine the potential 
effectiveness of sound attenuation devices during pile driving 
activity. Additional discussion on the PIDP and the results of its 
monitoring program is contained throughout this document.
    CALTRANS obtained an IHA from NMFS for the PIDP (65 FR 35047, June 
1, 2000), which established a safety zone around each pile driving site 
where underwater sound pressure levels (SPLs) were anticipated to equal 
or exceed 190 decibels (dB) re 1 micro-Pascal (micro-Pa) with a maximum 
root mean square (RMS) sound pressure level averaged over a 35-
millisecond time frame (Harris, n.d.; DOT, 2001)). This IHA also 
included several other stipulations about pile driving operations and 
requirements for marine mammal monitoring and reporting. During the 
PIDP, 3 large steel piles each required approximately 5 hours total 
driving time to reach the specified ``tip'' depth.
    Based on the PIDP experience, it is expected that the 259 in-Bay 
piles could require about 1,300 hours of total pile driving time or 
approximately 5 hours total for each pile to reach the specified tip 
depth. However, the contractor will be allowed to drive simultaneously 
at multiple locations. Furthermore, it is possible that piles necessary 
for the YBI portion, the skyway, and the Oakland approach structures 
would be driven simultaneously. Pile driving will be allowed to begin 
only from 7 a.m. to 8 p.m., 7 days a week. Pile driving that is 
underway at 8 p.m. will continue until driving of that pile segment is 
complete. If the contractor uses piles consisting of multiple segments, 
it is expected that the first segments driven will take less energy and 
drive faster than subsequent segments because the top Bay sediments are 
soft, with hard mud and soft rock at deeper levels. If the contractor 
uses a pile that is driven in one piece, early driving will take less 
energy and progress faster than later driving. While the total time 
that the hammer is operating will be the same in both cases, the total 
placement time for multiple segments will be longer.
    In a typical pile-driving scenario, the first pile segment would 
require about 1 hr of driving time. The next segment would then be 
welded to the driven segment. This process takes 2 to 3 days. After 
welding is complete, 3 to 4 hours would be required to drive the pile 
to tip elevation. The actual time would depend on local substrate 
conditions.
    In addition to in-Bay pile driving, the East Span Project will 
include pile driving on YBI for construction of the YBI transition 
structures on the northeastern side of the island. These piles will be 
steel-driven piles, which are conventionally used in building 
construction. Unlike in-Bay pile driving which may require hammer 
energy

[[Page 64597]]

levels up to 1,700 kJ, pile driving activity on YBI will require hammer 
energy levels less than 100 kJ. A total of approximately 2,950 piles 
will be needed to support the YBI transition structures. Each pile will 
require about 30 minutes of driving time; therefore, it is estimated 
that the East Span Project will include a total of about 1,500 hours of 
driving time for piles on YBI.
    To construct all permanent structures, contractors will also 
install piles to found temporary structures, supports, falsework, a 
barge dock and trestles. These temporary structures are required to 
facilitate construction and support the permanent structures until they 
are self-supporting. Since the temporary structures will be designed by 
the contractor, their exact nature (size, type, quantity, etc.) will 
not be known until the contractors submit their plans to CALTRANS. 
While the number of piles placed to found the structures will be large, 
it is expected that they will be of a smaller size than the permanent 
structures since they are temporary and are not designed for traffic or 
seismic loading. There may be 1,000 to 2,000 temporary piles. These 
piles are expected to be 0.5 m (18 in) to 0.9 m (36 in) in diameter and 
12 m (40 ft) to 30 m (100 ft) long. A vibratory driver/extractor will 
be used to install and remove these temporary piles, with energy levels 
less than 100 kJ. Driving time for each pile is likely to be 3 to 5 
hours; therefore, the estimated range for driving time for the 
temporary structures varies from 3,000 to 10,000 hours.
    The East Span Project would take 7 years to complete, plus 2 years 
to remove the existing East Span. Seismic safety and lifeline criteria 
would be achieved for westbound traffic 4 years after the start of 
construction and, for eastbound traffic, 5 years after the start of 
construction. The eastbound structure of the Skyway will be built 
first. Once all the piles supporting the piers for the eastbound 
structure are driven, construction will start for the westbound 
structure of the Skyway.
    Construction will begin at the Oakland Approach and progress 
towards YBI, from Pier E16 to Pier E-3. Piers E-16 through E-7 for the 
eastbound and westbound structures of the Skyway will be surrounded by 
sheet-pile cofferdams that will be dewatered before the start of pile-
driving. The sheet-pile sections for the cofferdam will be driven by a 
vibratory hammer. Cofferdam dimensions are approximately 84 ft (25 m) 
by 63-68 ft (19-20 m).
    Construction began in early 2002. For more detailed description on 
the work proposed by CALTRANS and potential environmental impacts, 
please refer to the CALTRANS application and/or the Final Environmental 
Impact Statement (Final EIS) prepared by the Federal Highway 
Administration (FHWA).

Comments and Responses

    A notice of receipt and request for 30-day public comment on the 
application and proposed authorization was published on November 26, 
2001 (66 FR 59001). During the 30-day public comment period, comments 
were received from the Marine Mammal Commission (the Commission) and 
CALTRANS. After the end of public comment period, letters were received 
from the Natural Resources Defense Council (NRDC), Campbell, George, 
and Strong, L.L.P. (CG&S) on behalf of Gunderboom, Inc., and an 
individual member of the public. These late comments are a part of this 
Administrative Record and were given full consideration in making a 
final determination in this matter (and are addressed within the text 
of this document). However, late comments that simply reference and 
either support or contradict comments that were submitted within the 
public comment period are not discussed in this document. In addition, 
because some public comments raised issues that needed resolution prior 
to NMFS making its determinations under section 101(a)(5)(D) of the 
MMPA, NMFS has incorporated into this document additional information 
that it requested from CALTRANS in reference to the statements 
submitted by the commenters. Finally, because the issue under 
consideration here is the issuance of an IHA to CALTRANS for the taking 
of marine mammals incidental to the activity, and because an IHA to 
CALTRANS does not authorize the CALTRANS' activity as such 
authorization is not within the jurisdiction of the Secretary of 
Commerce, comments that were submitted regarding subjects other than 
marine mammals, such as water quality concerns, have not been addressed 
in this document.

Activity Concerns

    Comment 1: The Commission notes that the Federal Register notice 
does not address noise and other issues associated with destruction and 
removal of existing structures. The Commission recommends that NMFS 
consult with the applicant regarding any planned demolition activities, 
and provide authorization for potential takings of marine mammals that 
may occur as a result of such activities.
    Response: Bridge demolition activities will not take place until 
after completion of construction of the new span. Those issues will be 
addressed in a future incidental take application and potential 
authorization action. As mentioned, this activity will take several 
years to complete. During this IHA, CALTRANS expects to conduct the 
following activities: (1) Complete construction of eastbound pier E7 
(in cofferdam), (2) construct eastbound pier E6 (using bubble curtain), 
(3) start westbound Pier 16E (in cofferdam), (4) complete westbound 
pier 7E (in cofferdam), (5) start construction westbound pier 6E (in 
bubble curtain), and (6) possibly begin construction on pier E2. 
Presumably under a new IHA issued around October, 2004, CALTRANS will 
continue work on westbound piers E16 through E7 (in cofferdams) and E6 
through E3 (using bubble curtains).
    Comment 2: CALTRANS notes several minor technical corrections to 
the proposed authorization document. These corrections include that the 
31-millisecond (ms) time frame should be 35 ms.
    Response: NMFS has made several minor recommended changes as 
appropriate in this document without further reference. Use of the 35-
ms time frame will allow CALTRANS to monitor sound with standard noise-
meters with ``real-time'' results. Otherwise, CAlTRANS notes, it would 
need to post-process the data. From the calibrated audio tapes made 
during the PIDP, the 31-ms (1.32-sec) RMS level of a pile strike was 
originally measured and found to be the same as the impulse (35 ms). 
There was zero dB difference between the 31-ms impulse RMS from the 35-
ms sound level meter and that measured with the 31-ms RMS time 
constant. The 35-ms rise-time constant has been adopted in national and 
international standards as design goals for measurements of impulse 
sound level, the ``RMS'' Impulse (Harris, n.d.). Based on the data 
collected for the PIDP, averaging over 35 ms is a conservative measure 
of the maximum RMS SPL with respect to the Greenridge analysis 
(Greenridge, Appendix G in Illingworth and Rodkin, 2002) for pile 1D at 
103 m (338 ft) distant and 6 m (20 ft) deep the Greenridge-measured SPL 
is 195 dB, and the RMS impulse (31 and 35 ms) is 196 dB.

Marine Mammal Impact Concerns

    Comment 3: CALTRANS questioned the statement made by NMFS in the 
proposed authorization notice that both permanent in-Bay pile driving 
and pile driving on YBI has the potential to

[[Page 64598]]

harass harbor seals. CALTRANS notes that land-based pile driving will 
involve hammers with less than 100 kJ of energy. CALTRANS believes that 
marine mammals are unlikely to be harassed by land-based pile driving 
and therefore, monitoring should apply only to in-Bay pile driving.
    Response: NMFS agrees. During site visits, NMFS noted that a large 
hill (Yerba Buena Hill) was located between the YBI construction site 
and the YBI haulout. Therefore, with the combination of this permanent 
acoustic barrier and the low energy level for this pile driving 
activity, no impacts are anticipated at the YBI haulout and therefore 
monitoring by the SF-OBB monitoring team is not warranted.
    However, the YBI haulout has been a pinniped control site for the 
monitoring program under CALTRANS' IHA for the Richmond San Rafael 
Bridge (see 67 FR 61323, September 30, 2002) for several years. 
Therefore this site will continue to be monitored by CALTRANS and any 
changes in harbor seal activity will be noted.
    Comment 4: CG&S states that the source level of acoustic wave 
energy that will be generated in the water of SFB will be approximately 
265 dB, and possibly greater. CG&S also states, that instantaneous 
lethal effects (rupturing of internal organs such as eyes and swim 
bladders) for aquatic organisms are well documented for energy levels 
of 204 dB, with delayed lethal effects occurring with energy levels 
down to 180 dB, and sub-lethal effects beginning as low as 170 dB.
    Response: The PIDP had a measured pile-driver energy of 900 kJ with 
a measured underwater peak pressure of 207 dB (re 1 uPa) at a distance 
of 103 m (338 ft) and 191 dB at a distance of 358 m (1174.5 ft). Greene 
(2001) corrected for the larger hammer size expected to be used at SF-
OBB and calculated excess attenuation of approximately 30 dB per 
tenfold increase in distance and, after applying the spreading loss 
formula, estimated that the pile driving source level (at 1 m (3.3 ft)) 
would be 268.5 dB (re 1 microPa) for the 1,700 kJ hammer. This 30-dB 
level is close to the 28-dB change observed at a Hong Kong refueling 
facility.
    However, the estimated 268.5 dB (re 1 microPa) for the 1700 kJ 
hammer is made by taking measurements made in the far-field and 
extrapolating those measurements to the near-field. Estimating a source 
level from the far-field assumes that the sound emanates from a single 
point, and that the level reported is measured 1 m (3 ft) from that 
point. This method is useful for comparing sound sources against each 
other. However, the 1700-kJ hammer is not a point source; there is no 
hypothetical location one meter from it where measurements could be 
made. Because of the dispersed nature of the sound, the procedure used 
in estimating a source level from the far-field gives a poor prediction 
of the levels an animal could actually receive in the near-field. Near-
field received levels are expected to be considerably less than the 
far-field estimates predict.
    Based on a formula provided by Greenridge Sciences, CALTRANS has 
made a rough extrapolation of the measurements made in the farfield 
back to 1 m (3.3 ft) that would put the source level at about 233 dB re 
1 microPascal and an unmitigated underwater SPL for the 1700 kJ hammer 
to the 190-dB isopleth is estimated to be approximately 100 m (328 ft). 
This 190-dB isopleth is where current NMFS policy conservatively holds 
that onset of Level A harassment occurs for pinnipeds. Therefore, to 
the extent practicable, activities should avoid exposing pinnipeds to 
sound pressure levels exceeding this value in order to limit Level A 
harassment (injury). This does not mean that pinnipeds would be injured 
at the 190-dB isopleth distance, only that the 190-dB SPL is the point 
above which some potentially serious problems in the hearing capability 
of marine mammals could start to occur. We note that the 190 dB (re 1 
uPa (rms)) criterion was established as an interim criterion that is 
still evolving. Newer information indicates that 190 dB is extremely 
conservative and that Level A harassment is unlikely to occur at that 
level.
    Also, NMFS does not concur with the commenter that SPLs of 180 to 
204 dB would necessarily result in lethal effects for fish. Studies 
suggest that intense sound may result in damage to the sensory hair 
cells in the ears of fish. Hastings et al. (1995, 1996) studied the 
effects of intense sound stimulation on the inner ear and lateral line 
of the oscar (Astronotus ocellatus) and Cox et al.(1986a, 1986b, 1987) 
exposed goldfish (Carassius auratus) to pure tones at 250 and 500 Hz at 
204 and 197 dB, respectively. They found some indications of sensory 
hair cell damage. Enger (1981) determined that some ciliary bundles 
(the sensory part of the hair cell) on sensory cells of the inner ear 
of the cod (Gadus morhua) were destroyed when exposed to sounds at 
several frequencies from 50 to 400 Hz at 180 dB for 1-5 hours. In 
reviewing the results of their study and that of the previous studies, 
Hastings et al.(1996) suggested that sounds 90 to 140 dB above a fish's 
hearing threshold may potentially injure the inner ear of a fish. This 
suggestion was supported in the findings of Enger (1981) in which 
injury occurred only when the stimulus was 100 to 110 dB above 
threshold at 200 to 250 Hz for the cod. Hastings et al. (1996) derived 
the values of 90 to 140 dB above threshold by examining the sound 
levels that caused minimal injury in the oscar, and then hypothesizing 
that extensive injury would require more energy. They conservatively 
suggest that received levels (RLs) of 200 dB to 240 dB would 
potentially cause damage to sensory hair cells in non-hearing 
specialist fishes. Calculations for hearing specialist fish using the 
Hastings (1996) values (i.e., 90 to 140 dB above threshold) 
conservatively indicate RLs of 140 to 190 dB continuously for at least 
one hour would be necessary to induce hearing damage. Also Hastings et 
al. (1995) showed that the oscars recovered within 1 day, suggesting 
that the impairment was not permanent.
    In addition, the primary potential for non-auditory impact to 
fishes would be resonance of fish swim bladders. Studies show that the 
resonant frequency of the swim bladder is considerably above the 
frequency of best hearing. It is not expected, therefore, that 
resonance of the swim bladder would play a significant role in response 
to low-frequency sound, especially since only larger fish would have 
swim bladders large enough to resonate. While NMFS does not believe the 
evidence supports a finding that instantaneous lethal effects are 
likely for energy levels of 180 to 204 dB, it does believe that 
mitigation measures implemented to reduce the impacts to marine mammals 
and threatened/endangered species will have benefits for other marine 
life as well.

Mitigation Concerns

    Comment 5: The Commission believes that NMFS' preliminary 
determinations are reasonable provided all reasonable measures will be 
taken to ensure the least practicable adverse impact on affected 
species of marine mammals. In that regard, the Commission notes that 
CALTRANS indicates that a fabric barrier sound attenuation system 
proved effective in reducing SPLs generated during the PIDP. It is 
unclear however, whether this method will be employed during the 
proposed pile-driving operations, or, in the alternative, that CALTRANS 
has made a showing that using such a system is not practical.
    Response: An explanation of the PIDP findings and CALTRANS analysis 
are provided here, followed in later comments and responses with

[[Page 64599]]

additional commenter concerns and NMFS determination on mitigation.
    The PIDP study involved driving three piles, with two different 
sizes of hammers and the use of two different methods of underwater 
sound attenuation. The test piles, Piles 1, 2 and 3, were made of steel 
and were 2.4 m (8 feet) in diameter. Pile 1 was driven straight down 
and did not use any sound attenuation. Pile 2 was a battered pile 
angled 1h:6v to the east and used an air bubble curtain. The single-
ring air-bubble curtain provided a curtain of air around the pile to 
attenuate noise from driving activities. Bubbles emerged from a 
submerged piping system that surrounded the pile template (used to hold 
the hammer/pile in place). The piping system was comprised of three 
10.2-cm (4-in) diameter perforated polyvinyl chloride (PVC) pipes 
attached to a steel frame, forming a 30.5-m (100-ft) diameter octagonal 
ring. Two rows of 0.1-centimeter (0.04-inch) diameter holes were 
drilled into the PVC pipes. The bubble curtain system was fabricated 
and assembled off-site, then transported to the pile-driving site using 
a barge-mounted crane. The piping system ring was then submerged to the 
Bay floor to encircle the pile template. Air was supplied from a 1,600 
ft\3\/min (cfm; 45.3 m\3\/min) compressor located on the PIDP barge. 
Though Pile 2 was driven at an angle, the bubbles streamed straight up 
to the water surface, potentially providing less attenuation near the 
surface than at greater depths. A similar system was used by Wursig et 
al. (2000) for attenuating noise received by dolphins during pile 
driving activities for an airport expansion.
    Pile 3 was a battered pile angled 1h:6v to the west and was 
surrounded by a proprietary method of sound attenuation referred to as 
a fabric barrier system with an aerating mechanism. The fabric barrier 
system consisted of an in-water, double-layer fabric curtain with a 
single 7.6-cm (3-in) diameter pipe between the two fabric sheets and 
three 7.6-cm (3-in) diameter pipes between the inner fabric layer and 
the pile. The fabric curtain was made of water-permeable material which 
enclosed the pile template. The top of the curtain attached to the pile 
template at a level a few meters above the surface of the water. The 
bottom was attached with beams to the bottom of the template. The 
fabric barrier system with aerating mechanism had a 10.7-m by 22.9-m 
(35-ft by 75-ft) rectangular footprint. This proprietary fabric barrier 
system with aerating mechanism was assembled and attached to the 
template off-site. The template/air bubble and fabric barrier was 
transported by barge to the Pile 3 location. Air was supplied from the 
same 1,600-cfm compressor that was used on Pile 2; however, air was 
supplied to four pipes which were arranged in a smaller footprint than 
for the air bubble curtain, thereby providing a higher density of air 
bubbles around the pile.
    Each pile was made up of four 33-m (108-ft) long sections which 
were driven and welded together in succession until the full length of 
the pile was achieved. Two types of Menke hydraulic hammers were 
employed to drive the piles; a small hammer rated at 500 kJ, and a 
large hammer rated at 1,700 kJ.
    Sound measurements were taken during pile driving, and marine 
mammals were monitored at the project site and at harbor seal haul-out 
site on YBI. Problems were encountered with the collection of data 
about sound pressure levels. As a result, the information about sound 
pressure levels that CALTRANS has obtained to date is limited. Based on 
the available data, the distances to the 190 dB contour for the large 
hammer without attenuation was estimated for each test pile driven. 
(The underwater sound level boundary for the pinniped safety zone was 
specified by the IHA as 190 dB re 1 mPa RMS (impulse) to protect 
pinniped hearing). Field measurements indicated that this 190 dB re 1 
microPa RMS (impulse) contour would be between 100 and 350 m (328 and 
1,148 ft) for the unattenuated pile (Pile 1) and the bubble curtain 
pile (Pile 2) and less than 100 m (328 ft) for the fabric barrier 
system with aerating mechanism (Pile 3).
    The PIDP Report (CALTRANS, 2001) determined that:
    the air bubble curtain is effective and adaptable to a seafloor 
with either a sloping or flat bottom. The air bubble curtain has a 
disadvantage in that fast currents in deep water may divert the air 
bubbles at an angle thereby reducing the effectiveness of the 
curtain. However, even with strong currents during the PIDP, the 
bubbles always surrounded Pile 2. Assembly of the bubble ring must 
typically be done off-site where sufficient land area is available 
for construction. For repeated use during the proposed East Span 
Project, this system could be redesigned to better withstand the 
pressures of being repeatedly raised to the surface. When compared 
to the fabric barrier system with aerating mechanism, there would be 
a larger economy of scale if it were designed for multiple reuse. 
The air bubble curtain is advantageous in that it does not need to 
be attached to the pile template itself, and marine construction 
equipment can easily maneuver around and over the site without any 
hindrance from the air bubble curtain. Marine construction equipment 
does not appear to affect the operation of the air bubble curtain. 
For reuse, the air bubble system's lack of bulk reduces the 
deployment logistics of relocating it to other pile locations. Once 
deployed, this system requires minimal inspection. With easier 
deployment maneuverability, and minimal inspection, the chances for 
time consuming delays would likely be decreased. For the PIDP, the 
bid cost was $120,000 for one installation.
    The fabric barrier system with aerating mechanism would be most 
effective in an area where a flat or consistently level bottom 
exists. Differences in bottom contour would result in a gap between 
the bottom of the curtain and the seafloor where sound would not be 
attenuated. For the proposed East Span Project, this system might be 
redesigned to be smaller for a single pile or much larger for a 
whole pier system. When compared with the air bubble curtain, there 
would be a smaller economy of scale if this system were designed for 
multiple reuse. Designing this system for reuse may include moving 
the template off-site, fitting different length curtain to it, and 
returning the refitted template back out to the project site. This 
could reduce the possibility of a gap between the bottom of the 
curtain and the sloping seafloor bottom. Costs would increase if the 
system needed to be redesigned for varying bottom elevations. Strain 
on the system from currents is less of a problem with this device 
than with the air bubble curtain alone, as the weight of the 
(fabric) curtain typically keeps the system nearly vertical. For the 
PIDP, the fabric barrier system was attached to the pile template by 
the proprietor of the system. In future applications, this can be 
expected to be performed off-site. The bulkiness of this arrangement 
makes movement to the project site and movement between piles to be 
driven very difficult. The first attempt to deploy this system at 
the PIDP had to be postponed because in windy weather the (fabric) 
curtain and template effectively acted as a sail. The height of this 
system and having it welded to the template does not allow for easy 
maneuverability for the marine equipment. For example, a derrick 
barge cannot maneuver over it, and equipment on the barge must reach 
over the barrier to the pile being driven. Once deployed, this 
system requires inspection of the condition of the zippers in the 
fabric and the bottom alignment. Any damage to the fabric barrier 
system would likely require removing the template and barrier from 
the water to conduct repairs. This would cause time-consuming delays 
to the pile driving operations. For the PIDP, the bid plus change 
order cost was $580,000 for one installation at Pile 3. This 
included an additional bubble ring between the curtain and the pile, 
which was not in the project specifications, but likely aided in 
sound attenuation.
    CALTRANS believes that an air bubble curtain is preferable to the 
fabric curtain in that the air bubble curtain does not need to be 
attached to the pile template itself and the marine equipment needed on 
site can easily maneuver around and over the site without any 
hindrance. The air bubble

[[Page 64600]]

system also results in lower deployment logistics when moving it around 
to other piles to be driven. Once deployed, the air bubble system 
requires minimal inspection. With easier deployment, maneuverability, 
and minimal inspection, the chances for costly project delays will be 
decreased. In addition, a fabric barrier/air bubble system would have 
to be designed to surround the entire template and pile cap (4 or 6 
pile group of piles driven through sleeves in the pile cap). This would 
require the use of larger or more compressors to the extent that it may 
require multiple barges for support. This could cause significant 
congestion around the footing and additional delays related to 
installing and moving the bubble curtain, installing the piles, and 
completing construction of the footing.
    In order to adjust the fabric barrier/air bubble system for the 
varying bathymetry in the Bay, the system would have to be removed from 
the Bay and reconfigured to meet the bathymetric conditions at each 
pier. An air bubble curtain will allow for a consistent close fit of 
the bottom of the curtain to the bay mud.
    A fabric barrier/air bubble system would require a complete 
redesign and construction of a new system of false work for the support 
of the pile cap-footing box due to the large lateral forces that would 
be applied to this structure by the flow of Bay currents against the 
fabric. The placement of the fabric barrier/air bubble curtain can be 
expected to only be possible at slack tides, with very low winds due to 
the sail effect of the fabric barrier. This too, will cause delays in 
placement of the system and the driving of the piles.
    As a result of this analysis, NMFS determined that the air bubble 
curtain had the potential to provide the means for effecting the least 
practicable adverse impact on the affected species and stocks of marine 
mammals, but wanted CALTRANS to provide another demonstration of the 
air bubble curtain's effectiveness in water currents than was shown at 
the PIDP. Subsequent testing of the air bubble curtain has indicated 
that it will effectively attenuate sound (see Response to Comment 6).
    Comment 6: CG&S states that based on the PIDP “the unconfined 
air bubble system provided little or no attenuation of harmful energy 
levels; however, CALTRANS is proposing this type system for the entire 
East Bay project. CG&S believes that the use of the confined air bubble 
system with fabric curtain would not only reduce energy levels but also 
serve as a physical barrier to exclude (marine mammal) entry into the 
project area.
    Response: CALTRANS has proposed to use the air bubble curtain to 
construct eastbound and westbound piers E6 through E3. CALTRANS would 
also construct eastbound and westbound piers E16 through E7 (in 
cofferdams, not using an air bubble curtain). Work done within 
cofferdams would use a 500-kJ hammer whenever possible, but switching 
to the 1700 kJ hammer only if stiffer sub-bottom sediments are 
encountered.
    NMFS believes that the PIDP did not provide an accurate assessment 
of the capability of the air bubble curtain due to the failure to 
compensate for the currents in the area. One of the problems noted 
during the PIDP was that the air bubbles did not completely enclose the 
piles during periods with tidal currents. As a result, CALTRANS 
redesigned the air bubble curtain system and tested that system in 2002 
and again in 2003 so that the new design of the bubble curtain 
completely enclosed all permanent in-water piles/pile groups during the 
pile driving process. One reason for the delay in issuing this IHA was 
our review of the redesigned air bubble curtain to ensure that marine 
mammals would be protected to the greatest extent practicable. That 
report was released on July 23, 2003. In summary, the effectiveness of 
a bubble curtain consisting of two or more rings over the single-bubble 
curtain used in the PIDP for reducing underwater sound pressures during 
marine pile driving was assessed through underwater sound pressure 
measurements. This was conducted when the three 108-m long, 2.4 m 
diameter piles driven in 2000 as part of the PIDP, were restruck in 
December, 2002. During the measurements, the bubble curtain system was 
turned on and off. The restrike involved driving the piles at refusal 
with the hammer at maximum energy (1600-1740 kJ).
    The reduction in sound pressures provided by the bubble curtain 
system ranged considerably. The direct reduction in sound pressures for 
piles 1 and 2 was 6 to 17 dB for peak pressures and 3 to 10 dB for RMS 
SPLs. Piles 1 and 2 were next to each other. SPL reductions at Pile 3, 
which was in shallower water, were over 20 dB for both peak pressures 
and RMS SPLs on the north side. However, reductions on the south side 
were much less. Close to pile 3 on the south side, the reductions were 
on the order of 5 to 7 dB. Further away at about 450 m (1476 ft) south, 
the reductions were only about 2 dB. Uneven bottom topography around 
pile 3, which could have compromised the bubble curtain performance 
near the bay bottom is suspected to have resulted in lower reductions 
to the south.
    Analysis of individual pile strike impulses indicates that the 
bubble curtain reduced sound pressure at all measurement positions at 
frequencies above 1 kHz. There was a reduction in sound pressures below 
500 Hz where the bubble curtain worked particularly well.
    Measurements of peak pressures made at about 100 m (328 ft) were 
consistent with the measurements made during the PIDP in 2000. Those 
measurements were the basis for predictions of the maximum peak 
pressures during the SF-OBB east span construction. With the exception 
of the 450 m (1476 ft) south position, predicted peak pressures used in 
the NMFS October 30, 2001 Biological Opinion on the effects of 
construction of the East Span of the SFOBB on listed species were lower 
than those measured. At 450 m (1476 ft) south, measured peak pressures 
were 5 to 8 dB higher than predicted. Conversely, peak pressures at 450 
m (1476 ft) to 500 m (1640 ft) north were 0 to 6 dB lower than 
predicted.
    RMS SPLs did not exceed 190 dB at any of the measurement positions 
(between 65 and 500 m) when the bubble curtain was operating. SPLs of 
180 dB RMS did not extend out to the 450 m (1476 ft) south for pile 1, 
but did not exceed 172 dB at 450 m (1476 ft) north. With the bubble 
curtain off, the 190-dB RMS SPLs extended out to somewhere between 200 
m (656 ft) to 300 m (984 ft) for piles 1 and 2, and less than 100 m 
(328 ft) for pile 3.
    Comment 7: On December 17, 2001, CALTRANS requested that the 
paragraph in the proposed authorization notice regarding barrier 
systems be removed since the marine pile-driving attenuator system that 
will be installed by CALTANS is to protect fish and is not intended to 
protect marine mammals.
    Response: While the CALTRANS application did not indicate that a 
sound-attenuating device would be installed during pile driving at SF-
OBB, by the time the proposed authorization notice was published on 
November 26, 2001, the NMFS Biological Opinion on CALTRANS' 
construction of a replacement bridge for the East Span of the SF-OBB 
had been issued. That document notes that ``application of an air 
bubble curtain to attenuate sound is expected to restrict th[e] area of 
direct mortality [i.e., for fish], a radius of approximately 69 meters 
and the proposed monitoring program will allow for confirmation of the 
bubble curtain's effectiveness '' Therefore,

[[Page 64601]]

while NMFS agrees that the term ``barrier systems'' was incorrect, in 
accordance with the Biological Opinion, some method to decrease the 
SPLs would be necessary to protect listed fish species. In addition, 
this would serve as a practical marine mammal mitigation measure. 
Therefore, the information provided in that paragraph of the proposed 
Federal Register notice has been expanded in this document to include 
NMFS determination on effective mitigation.
    Comment 8: CALTRANS requests the following clarifications be made 
if NMFS intends to require the pile-driving attenuator in the IHA: (1) 
although the attenuator planned for use is similar in concept to the 
one that was used in the PIDP, it will have a substantially enhanced 
performance; (2) use of the attenuator is only for driving the large 
in-Bay piles, not for the smaller, temporary in-Bay piles nor for any 
land-based piles; and (3) NMFS should clarify its intent (for requiring 
the attenuator to protect marine mammals).
    Response: NMFS agrees. In reviewing the Administrative Record on 
this IHA application, NMFS has determined that deployment of an 
improved air bubble curtain would effectively reduce impacts to marine 
mammals at the SF-OBB to the lowest level practicable. For example, at 
the Benicia-Martinez Bridge in California an unconfined air bubble 
curtain system was developed that used vertically-stacked air bubble 
rings and large volumes of air to reduce sound pressures. Findings 
indicate that this system resulted in sound pressure reductions of 19 
to 33 dB re 1 microPascal and 17 to 29 dB on an rms basis. At most 
measurement positions, peak sound pressures were reduced by over 22 dB 
and RMS SPLs were reduced by over 25 dB. The measurement results and 
discussion can be found in the report (Reyff, 2003) which is available 
upon request.
    Therefore, as a result of the findings made during the PIDP 
restrike and the investigation at the Benicia-Martinez Bridge, NMFS has 
determined that CALTRANS must install an air bubble curtain for pile 
driving for the in-Bay piles located at the SF-OBB. Based on CALTRANS 
redesign, this air bubble curtain system will consist of concentric 
layers of perforated aeration pipes stacked vertically and spaced no 
more than five vertical meters apart in all tide conditions. To 
address, in part, the issue of currents, CALTRANS has determined that 
the number of layers of pipe must be in accordance with water depth at 
the subject pile: 0-<5 m = 2 layers (1263 cfm); 5-<10 m = 4 layers 
(2526 cfm), 10-<15 m = 7 layers (4420 cfm); 15-<20 m = 10 layers (6314 
cfm); 20-<25 m= 13 layers (8208 cfm). The lowest layer of perforated 
aeration pipes must be designed to ensure contact at all times and 
tidal conditions with the mudline without sinking into the bay mud. 
Pipes in any layer must be arranged in a geometric pattern, which will 
allow for the pile driving operation to be completely enclosed by 
bubbles for the full depth of the water column and for a radial 
dimension of at least 2 m (6.6 ft) as measured from the outside surface 
of the pile.
    To provide a uniform bubble flux, each aeration pipe must have four 
adjacent rows of air holes along the pipe. Air holes must be 
1.6[dash]mm diameter air holes spaced approximately 20 mm apart. The 
bubble curtain system will provide a bubble flux of at least three 
cubic meters per minute, per linear meter of pipeline in each layer. 
Air holes must be placed in 4 adjacent rows. The air bubble curtain 
system must be in a frame to facilitate transport and placement of the 
system, keeping the aeration pipes stable, and providing ballast to 
counteract the buoyancy of the aeration pipes in operation.
    Comment 9: On April 23, 2002, CALTRANS informed NMFS that, with 
some modifications, the description of ``barrier systems'' should 
remain in the final IHA Federal Register notice as it provides 
information about the sound attenuating device to be used during the 
project. CALTRANS suggested the following language: ``The bubble 
curtain system will be used only when driving the permanent in-Bay 
piles. While the bubble curtain is required specifically as a method to 
reduce impacts to endangered and threatened fish species in SFB, it may 
also provide some benefit for marine mammals. The NMFS' Biological 
Opinion and the California Department of Fish and Game's (CDFG) 2001 
Incidental Take Permit also allow for the use of other equally 
effective methods, such as cofferdams, as an alternative to the air 
bubble curtain system to attenuate the effects of sound pressure waves 
on fish during driving of permanent in-Bay piles (NMFS 2001; CDFG, 
2001). Piers E-16 through E-7 for both the eastbound and westbound 
structures of the Skyway will be surrounded by sheet-pile cofferdams, 
which will be dewatered before the start of pile-driving. De-watered 
cofferdams are effective sound attenuation devices. For Piers E3 
through E6 of the Skyway and Piers 1 and E2 of the Self-Anchored 
Suspension span, it is anticipated that cofferdams will not be used: 
therefore, a bubble curtain will surround the piles.''
    Response: NMFS agrees and has inserted the recommended text as it 
clarifies where CALTRANS is required to install the air bubble curtain 
(see Mitigation). It should be noted that NMFS has determined that 
installation of the redesigned bubble curtain (described in response to 
comment 8) along with additional mitigation measures described later in 
this document (see Mitigation) will reduce marine mammal impacts to the 
lowest level practicable. Therefore, NMFS has determined that the piles 
for Piers E3, E4, E5, and E6 of the Skyway, as well as for Piers 1 and 
E2 of the Self-Anchored Suspension span, which will not be surrounded 
by cofferdams, must have an air bubble curtain system surrounding each 
pile driven to attenuate peak underwater sound pressure levels.
    Comment 10: GC&S states that ``it appears that CALTRANS has not 
considered the potential for marine mammals to wander into the project 
area during nocturnal periods of no activity. If this happens (and 
there is not a physical barrier to prevent this), the individuals that 
remain in the area during initial startup of the pile-driving activity 
could experience death or serious bodily injury. The use of the 
confined air bubble system (with fabric curtain) would not only reduce 
energy levels, but also serve as a physical barrier to exclude entry 
into the project area.''
    Response: NMFS has determined that the marine mammal monitoring 
program will effectively locate all pinnipeds in the vicinity of the 
pile-driving activity prior to beginning the driving of each pile. The 
IHA requires trained observers to conduct observations at least 30 
minutes prior to the start of all in-water, permanent pile-driving. If 
any marine mammals are observed, pile-driving cannot begin until the 
animals leave the 190-dB safety zone or until 15 minutes after the 
animal was last seen. In addition to monitoring, requirements for the 
installation of an improved air bubble curtain and to incorporate 
``soft-start'' of the hammer will ensure that no pinnipeds (or 
cetaceans) will be injured or killed incidental to placement of piles 
at SF-OBB.
    Comment 11: The CG&S and others believe that the MMPA provides NMFS 
with the authority to require CALTRANS ensure the least practicable 
impact to marine mammals by the project.
    Response: NMFS agrees and believes that requiring CALTRANS to 
install and use the air-bubble curtain, as redesigned after the re-
strike and described in

[[Page 64602]]

response to comment 6, will result in the least practicable adverse 
impact to the affected species or stocks of seals or sea lions that 
might be in the area prior to starting pile driving.
    Comment 12: CG&S submitted additional documentation on June 18, 
2002, regarding the efficacy of a gravel-filled cofferdam for sound 
attenuation. CG&S concludes that dewatering the cofferdam by filling it 
with solid material may, at best, provide little to no reduction of 
noise levels and may actually intensify sound levels in some 
applications, rendering this technique ineffective for sound 
attenuation. The CG&S' supporting documentation provides a summary of 
the finding: ``A basic estimate of the sound propagation for the driven 
pile in the sand-filled cofferdam is made. The first order calculation 
for the geometry presented indicates about 10 dB loss due to this 
construction. This loss has reduced significance when considering the 
potential need for more hammer energy to drive the pile through the 
sand. The acoustic conditions could potentially be no better and even 
could become worse.''
    Response: CALTRANS plans to construct the eastbound and westbound 
piers E16 through E7 in dewatered cofferdams using a 500-kJ hammer, not 
a 1,700-kJ hammer unless resistence is met. However, as detailed in 
CALTRANS (2002b), the cofferdam is not simply dewatered and filled with 
sand. Instead, the bottom is dredged, a base-rock blanket is placed on 
the bottom of the cofferdam and a pile cap is placed in the cofferdam. 
After the cofferdam is dewatered to the extent practicable, the 
battered piles are driven through sleeves in the pile cap, not through 
the sand or rock (except for the 1.5 m (4.9 ft) of base rock under the 
pile cap). Figure 2-3 of CALTRANS (2002b) provides a good illustration 
of the expected decoupling of the airborne sounds from the pile driver 
into the water column when pile driving is conducted in the relatively 
shallow water between piers E16 and E7. Essentially, it does not matter 
even if there is water between the voids of the rock fill inside the 
cofferdam during pile driving. This is because the rock fill starts at 
the mudline and continues down to the bottom of the excavated coffer 
cell. Therefore, little or no energy is transmitted to the Bay water 
through the locking fill or the water in the voids of the locking fill. 
The pile is not surrounded by Bay waters and little or no energy is 
transmitted to the Bay waters. As a result, NMFS has concluded that the 
use of cofferdams is an effective method to reduce the sound pressure 
level of pile driving into the water environment.
    Comment 13: CALTRANS comments that the restriction on start-up of 
pile driving until marine mammals have moved out of the area should be 
revised to include an alternative of a time period of 15 minutes. 
CALTRANS is concerned that costly delays of up to $38,000/hour could 
result from a delay.
    Response: Both the proposed and final documents make clear that 
pile driving cannot begin until marine mammals have left the respective 
safety zone for their appropriate taxa, no matter how long the period. 
This is appropriate since CALTRANS did not request the taking of marine 
mammals by Level A harassment, which becomes a potential means of take 
if animals are still within the safety zone when pile driving 
commences. However, as noted in the IHA, if an animal dives below the 
water surface and does not reappear within the safety zone within 15 
minutes, then the animal may be presumed to have left the safety zone 
and pile driving can begin. If the presence of seals or California sea 
lions within the safety zone seriously compromises CALTRANS' activity, 
CALTRANS will need to contact the Regional Administrator, NMFS, for 
appropriate resolution.

Monitoring and Reporting Concerns

    Comment 14: CALTRANS proposed that approval of a monitoring plan 
prior to any construction activity would unnecessarily delay 
construction of the first project-related activity, a fill surcharge 
contract on land and in intertidal sand flats at the Oakland Touchdown, 
which is scheduled to start before the IHA is issued. This contract 
would be delayed if this requirement were to remain in place. CALTRANS 
notes that such a plan was not required in advance of the IHA for the 
PIDP.
    Response: The fill contract work is on land and in intertidal sand 
flats at the Oakland Touchdown and is therefore not expected to have a 
potential for marine mammal harassment. Since this work does not 
include any pile-driving and the location of the work is far from the 
YBI haulout site, it was proper for CALTRANS to proceed with this work 
prior to issuance of an IHA. Work began in early March, 2002 and 
included monitoring for herring spawn in the area five times a week for 
about 6 weeks (late February through March). No seals were observed 
during monitoring.
    CALTRANS submitted a site-specific monitoring plan to NMFS for 
review in May, 2002. That plan has been reviewed by NMFS and is 
discussed in more detail in this document. The monitoring program 
associated with the PIDP was contained in the CALTRANS application for 
an IHA; a separate report was not necessary to establish the monitoring 
requirements contained in the IHA.
    Comment 15: CALTRANS notes that the proposed authorization notice 
proposes safety zone monitoring before the entire East Span Project 
begins. This is not feasible since the safety zones are located around 
specific pile sites. CALTRANS proposes baseline monitoring of the 
general project areas rather than monitoring safety zones for which 
locations will not have been defined by then. The fill surcharge 
contract (see previous comment) is scheduled to begin construction 
before the marine mammal monitoring will take place. The nature of this 
work and its distance from marine mammal haulouts and foraging areas 
suggests that this work will not result in the harassment of marine 
mammals. CALTRANS therefore proposes to begin baseline monitoring 14 
days prior to construction of the second project contract, the Skyway 
contract, which will involve pile driving and other major in-Bay 
construction activities. CALTRANS believes that this will meet the 
intent of this requirement to collect background data about marine 
mammal behavior prior to the beginning of construction work that has 
the potential to incidentally harass marine mammals.
    Response: NMFS concurs. A detailed description of the visual 
monitoring program recommended by CALTANS and accepted by NMFS is 
provided later in this document (see Monitoring).
    Comment 16: CALTRANS recommends that in several places in the 
proposed authorization notice, NMFS substitute ``permanent in-Bay pile-
driving'' in place of ``all pile driving'' since only in-Bay pile 
driving will be monitored by marine mammal observers.
    Response: While NMFS agrees to the modification, it must point out 
that in-Bay, land-based, and temporary pile driving activities all have 
some monitoring associated with it. However, only the in-Bay pile 
driving has the requirement for monitoring during all pile-driving 
activities.
    Comment 17: CALTRANS recommends that, similar to the PIDP 
monitoring, monitoring be required for a minimum of 30 minutes prior to 
the initiation of each pile-driving episode. Also, CALTRANS recommends 
having one team of observers to observe the safety zone at each in-Bay 
pile-driving site. Therefore, multiple teams would be required if pile 
driving is occurring at multiple sites at any one time.

[[Page 64603]]

    Response: NMFS agrees, noting that these proposed requirements were 
also contained in CALTRANS May, 2002 monitoring plan.
    Comment 18: CALTRANS notes that no offsite monitoring sites (i.e. 
haul-outs) offer comparable conditions for use as a control site. Mowry 
Slough, for example, is quite different from the YBI haul-out as it is 
a pupping site, is located in a different environment, and has far less 
ambient human disturbance. If it is included as a comparison site, 
CALTRANS proposes that the frequency of monitoring at YBI be conducted 
twice a week during driving permanent in-Bay piles.
    Response: In order to evaluate whether harbor seals use alternative 
hauling-out areas as a result of construction work at SF-OBB, CALTRANS 
is required to monitor at least one additional harbor seal haul-out 
within the Bay. Since Mowry Slough has been designated as a control 
site for the Richmond-San Rafael Bridge seismic retrofit work, NMFS 
recommends that this site continue to be monitored using the same 
protocol designed by researchers for that project.
    Comment 19: CALTRANS notes that land-based pile driving will 
involve hammer energy less than 100 kJ and believes that marine mammals 
are not likely to be harassed by land-based pile driving. Therefore, 
CALTRANS believes that monitoring should apply only to in-Bay pile 
driving.
    Response: The piles on YBI for construction of the YBI Transition 
structures are on the northeastern side of YBI and will be conventional 
steel-driven piles requiring hammer energy levels less than 100 kJ. 
With each pile requiring about 30 minutes of driving time, the 2,950 
piles will require about 1,500 hours at YBI. However, the YBI harbor 
seal haul-out site is located about 450 m (1,476 ft) from the closest 
planned piledriving activity and is separated from the activity by a 
large hill. Therefore, monitoring is unnecessary for this land-based 
pile-driving but monitoring will be conducted by the bi-weekly 
monitoring team from the Richmond Bridge project.
    Comment 20: The Commission believes that NMFS' preliminary 
determinations are reasonable provided that the visual monitoring of 
the safety zone to be conducted prior to and during pile driving 
operations is adequate to detect all marine mammals within the safety 
zone. According to CALTRANS, since pile driving is scheduled to occur 
from 7 a.m. to 7 p.m., visual monitoring in the late afternoon and 
early evening would be compromised during the winter months. The 
Commission recommends that this issue should be addressed in CALTRANS' 
detailed marine mammal monitoring plan to ensure that visual monitoring 
is effective during all periods in which pile driving activities are 
conducted.
    Response: On December 13, 2001, and April 23, 2002, CALTRANS 
notified NMFS that there was a discrepancy between the time period for 
pile driving activities in the IHA application and the construction 
specifications and that the time period provided in the IHA application 
was not accurate. The construction specification states: “No 
pile-driving activities are to be conducted between the hours of 8 p.m. 
and 7 a.m. Therefore, CALTRANS requested the change be made in this 
document. In addition, CALTRANS clarified, on December 17, 2001, that 
he specification also states that if a pile driving episode has started 
before 8 p.m., and is not completed by that time, it can be finished. 
Finally, CALTRANS' May, 2002 Marine Mammal Monitoring Plan notes that 
marine mammal observers will have night-time infra-red (IR) scopes or 
other tools to conduct monitoring during low light conditions.
    As noted by the Commission, night-time conditions may exist which 
will limit observations. In addition, IR-scopes have indicated limited 
usefulness. Marine mammal observers in other activities recently have 
employed Bushnell/ITT F5000 binocular night-vision devices (NVDs) 
(Lawson, 2000). Therefore, NMFS recommends that NVDs be available for 
use by each team as needed and, if not, additional work site lighting 
be provided to enhance visibility whenever NVD-trained observers are 
not available. It should be recognized that the safety zone needs to be 
visible only during the 30-minute period prior to the start of driving 
a pile segment, not at other times.
    Visual monitoring has two purposes: (1) to monitor the safety zone, 
and (2) to conduct marine mammal behavioral observations. Since pile 
driving, whether a single pile or a segment of a pile, cannot be 
stopped once started until the pile reaches its predetermined depth, 
and because sufficient opportunities exist during daylight period to 
make behavioral observations, stopping pile driving during periods of 
darkness (or fog) is not warranted, provided the entire safety zone can 
be effectively monitored for the entire 30-minute period prior to 
startup of each pile segment being driven. Therefore, NMFS is requiring 
CALTRANS to conduct monitoring and detailed reporting on activities 
during periods of darkness. NMFS will review this information prior to 
processing any subsequent requests for renewal of this IHA to determine 
if additional mitigation measures are necessary.

MMPA Concerns

    Comment 21: The Commission believes that, in situations where a 
temporary threshold shift (TTS) may lead to biologically significant 
behavior effects (e.g., an increased risk of natural predation or ship 
strikes), the activity should be considered as having a potential for 
injury (Level A harassment).
    Response: NMFS has addressed the issue of second order impact 
assessment in several previous small take authorizations, and without 
new scientific documentation on this issue, a detailed response is not 
warranted here. For reviewers interested in this discussion, refer to 
the small take authorizations for the USS WINSTON S. CHURCHILL shock 
trial (66 FR 22450, May 4, 2001) and the Surveillance Towed Array 
Sensor System Low Frequency Active sonar (67 FR 46712, July 16, 2002).
    Comment 22: The Commission believes that an across-the-board 
reclassification of TTS from Level A harassment to Level B harassment 
raises questions both in terms of the activities that involve the 
potential for repeated TTS harassment and, in general, cumulative 
effects.
    Response: First, whether TTS is Level B harassment or Level A 
harassment is irrelevant for this IHA since mitigation and monitoring 
requirements under the IHA should prevent TTS. While there is some 
recent published research to the contrary, the general state of 
knowledge indicates that a permanent shift in hearing threshold (PTS) 
can occur with repeated exposures of TTS without allowing animals to 
completely recover. However, in order for this to occur, the marine 
mammal would need to remain within a safety zone and not be detected by 
the marine mammal observer team for a significant period of time in 
order to incur repeated TTS sufficient to result in PTS injury from 
pile-driving source. Therefore, NMFS believes that, considering the 
previously observed behavior of pinnipeds in the vicinity of the PIDP, 
the monitoring and mitigation measures imposed and the transitory 
nature of those marine mammal species likely to be impacted, it would 
be very unlikely a marine mammal would incur a TTS impairment and 
virtually impossible for a marine mammal to incur a PTS injury. For 
proposed authorizations other than SF-OBB, NMFS will review each of 
these as

[[Page 64604]]

appropriate to determine whether there is a significant potential for 
TTS and whether that impact could lead to PTS.

Other Concerns

    Comment 23: One commenter asked what in-air noise mitigation was 
recommended.
    Response: Previously (see 68 FR 52332, September 2, 2003), NMFS 
determined that Level B disturbance in the air for California sea lions 
and northern elephant seals began at approximately 100 dBA, and for 
Pacific harbor seals at approximately 90 dBA. Based on airborne 
measurements made during the PIDP, airborne SPLs will be significantly 
below these levels within the safety zones that have been established 
under this IHA in order to prevent injury. Therefore, NMFS does not 
believe that in-air noise mitigation measures are needed to protect 
pinnipeds from injury. In addition, airborne acoustic measurements will 
be made during this IHA to determine whether Level B harassment is 
occurring on the nearest pinniped haulout.

Description of the Marine Mammals Potentially Affected by the Activity

    General information on California sea lions, Pacific harbor seals, 
gray whales and other marine mammal species found in California waters 
can be found in Caretta et al. (2002, 2001), which are available at the 
following URL: http://www.nmfs.noaa.gov/prot_res/PR2/Stock_Assessment_Program/sars.html. Refer to those documents for information 
on these species. The marine mammals most likely to be found in the SF-
OBB area are the California sea lion and Pacific harbor seal. From 
December through May gray whales may also be present in the SF-OBB 
area.

California Sea Lions

    While there is evidence that California sea lions historically used 
the Bay, they are rarely observed hauled out in the Bay (Bauer, 1999). 
However, since at least 1987, sea lions have been observed occupying 
the docks near Pier 39 in San Francisco, approximately 5.7 km (3.5 mi) 
from the project site. Pier 39 has now become a regular haul-out site 
for California sea lions. Currently, no other California sea lion haul-
out sites have been identified in the Bay. Approximately 85 percent of 
the animals hauled out at the Pier 39 site are males, and no pupping 
has been observed at this site or any other site in the Bay (Lander 
pers. comm. to CALTRANS, 1999).
    The number of California sea lions hauled out at Pier 39 ranged 
from 63 to 737 in 1998 and from 5 to 906 in 1997 (Marine Mammal Center, 
Sausalito data). For both years, the lows occurred in June and the 
highs occurred in August. In October 1999, 831 sea lions were observed 
on K dock at Pier 39. The trend in annual movement is for sea lions to 
first appear at the site after returning from the Channel Islands 
breeding area (over 483 km or 300 mi to the southwest) at the beginning 
of August (Bauer, 1999). Around late winter, the sea lions travel south 
to the breeding grounds, and numbers at the Bay haul-out site decline. 
The lowest numbers of sea lions at the Pier 39 haul-out are usually 
observed from May through July. However, the number of sea lions at the 
haul-out site fluctuates quite a bit throughout the year and even from 
one week to the next. For example, in June of 1998, a maximum of 574 
sea lions was observed on June 7\th\ while a low count of 63 was 
observed on June 25th (Lander pers. comm. to CALTRANS, 1999).
    While little information is available on the foraging patterns of 
California sea lions in the Bay, individual sea lions have been 
observed feeding in the shipping channel to the south of YBI on a 
fairly regular basis (Grigg pers. comm. to CALTRANS, 1999). Foraging by 
sea lions that utilize the Pier 39 haul-out site primarily occurs in 
the Bay, where they feed on prey items such as Pacific herring, 
northern anchovy and sardines (Hanni, 1995).

Pacific Harbor Seals

    Pacific harbor seals are the only species of marine mammal that 
breed and bear young in the Bay (Howorth and Abbott, 1999). There are 
12 haul-out sites and rookeries in the Bay and of those, only eight are 
used by more than a few animals at a time. Only three sites in the Bay 
are regularly used by more than 40 harbor seals at any one time; these 
are Mowry Slough, located in the South Bay, YBI, and Castro Rocks, 
located in the Central Bay (Spencer, 1997). The three closest haul-out 
sites to the project location are at YBI, Angel Island, and Castro 
Rocks. A recent aerial harbor seal count, conducted by D. Hanan of the 
California Department of Fish and Game, found 477 individuals in the 
Bay (Greene, pers. comm. to CALTRANS, 1999). It is important to note 
that not all harbor seals were counted, as some may have been under 
water during the survey.
    Harbor seals are present in the Bay year-round and use it for 
foraging, resting and reproduction. Peak numbers of hauled-out harbor 
seals vary by haul-out site depending on the season. Results of a study 
of 39 radio-tagged harbor seals in the Bay found that most active 
diving occurred at night and a majority of the diving time was spent in 
seven feeding areas in the Bay. The two feeding areas located closest 
to the project site are just to the south of YBI and north of Treasure 
Island. This study also found that the seals dove for a mean time of 
0.50 minutes to 3.33 minutes. Mean surface intervals or the mean time 
the seals spent at the surface between dives ranged from 0.33 minutes 
to 1.04 minutes. Mean haul-out periods ranged from 80 minutes to 24 
hours (Harvey and Torok, 1994).
    Pupping season in the Bay begins in mid-March and continues until 
about mid-May. Pups nurse for only 4 weeks and mating begins after pups 
are weaned. In the Bay, mating occurs from April to July and molting 
season is from June until August (Schoenherr, 1995; Kopec and Harvey, 
1995).

Pacific Harbor Seal Haul-Out Sites in the Vicinity of the East Span 
Project

    YBI is located in the Central Bay, adjacent to man-made Treasure 
Island. The SF-OBB passes through a tunnel on YBI. An important harbor 
seal haul-out is located on a rocky beach on the southwest side of YBI 
(Kopec and Harvey, 1995). Harbor seal re-sightings at the YBI haul-out 
site indicate long-term usage of the site (Spencer, 1997). Pile driving 
activity for the East Span Project will be performed on the northeast 
side of YBI and in the San Francisco Bay, between the northeast side of 
the island to the Oakland Touchdown area. The harbor seal haul-out site 
is located about 450 m (1,476 ft) from the closest planned pile driving 
activity on land and about 950 m (3,117 ft) from the closest planned 
pile driving activity in the Bay.
    Harbor seals haul out year-round on YBI, but it is not considered a 
pupping site as no births have been observed there. Occasionally, pups 
have been seen at an average of 1 pup per year, though more recently, 7 
pups were observed at one time in May, 1999 (San Francisco State 
University unpublished records, 1998-9). In a study of the haul-out 
site conducted between 1989 and 1992, males comprised 83.1 percent of 
the seals whose gender could be determined (Spencer, 1997). Peak 
numbers of harbor seals at this haul-out site have been observed from 
November to February. The maximum reported number of seals hauled out 
at one time is 344, counted in January 1992 (Kopec and Harvey, 1995). 
More recently, the number of seals counted at YBI ranged from 0 to 296 
for the period May 1998

[[Page 64605]]

to January 1999. Mean monthly counts for the same period range from 
approximately 15 in September 1998 to 107 in June 1999 (San Francisco 
State University, unpublished records 1998-1999). The abundance of 
harbor seals at this site during the winter months likely coincides 
with the presence of spawning Pacific herring near the island.
    Angel Island is a small haul-out site located approximately 7.4 km 
(4.6 mi) from the project site. A maximum count of 15 seals was 
observed in the 1980s and most recently, six harbor seals were seen in 
1989. No pupping has been observed at the site.
    The next closest haul-out site in the Bay is approximately 14 km 
(8.7 mi) away at Castro Rocks, near the Richmond end of the Richmond-
San Rafael Bridge. The Castro Rocks haul-out site is a recognized 
pupping site. A maximum of 176 harbor seals were observed at Castro 
Rocks in October 1999 (San Francisco State University unpublished 
records, 1998-9).

Gray Whales

    The vast majority of all gray whales are found in the Pacific Ocean 
along the western coastline of North America. Here, they spend their 
winters in the waters off Baja California and migrate more than 9,000 
kilometers (5,600 miles) north to spend their summers north of Alaska. 
They are typically seen off the California coastline from December 
through May as they migrate northward to the Bering and Chukchi Seas, 
and again in the return trip to Baja California.
    Gray whales have been sighted more frequently in recent years in 
San Francisco Bay. Reduced food supply in the Bering Sea has been 
suspected as the most probable cause. Gray whales have been sighted in 
the Bay in areas off Sausalito in Richardson Bay and the tip of the 
Tiburon Peninsula (approximately 11 km or 7 mi northwest of the project 
area) and as far south as the San Bruno Shoals area (approximately 23 
km or 14 mi southwest of the project area). Gray whales have been 
observed foraging in these areas. Sightings in the Bay have typically 
been made from December through May, during the whales' coastal 
migration. Calves may be expected during the migration north with 
mothers in March and May. Most recently, in February 2001, a pod of 
gray whales was observed near the Dumbarton Bridge in the South Bay.
    Gray whales heading to the San Bruno Shoals area would pass beneath 
the SF-OBB. It is likely that some of the whales that enter the Bay 
would swim through the two deep-water shipping channels beneath the 
West Spans of the bridge. Though the number of sightings of gray whales 
to the east of YBI and in the immediate vicinity of the SF-OBB is low, 
they are not precluded from swimming there to reach the San Bruno 
Shoals area or foraging near or in these areas.

Potential Effects on Marine Mammals and Their Habitat

    At this time, NMFS considers that underwater SPLs above 190 dB re 1 
micro-Pa RMS (impulse) could cause hearing injury to harbor seals and 
sea lions and SPLs above 180 dB re 1 micro-Pa RMS (impulse) could cause 
hearing injury to whales. In addition, the effects of elevated SPLs on 
marine mammals have the potential to cause annoyance, disruption of 
echolocation, masking, avoidance of an area, habitat abandonment, 
aggression, pup/calf abandonment, tissue rupture and hearing loss. 
Therefore, CALTRANS has determined that in-water pile driving outlined 
in the project description has the potential to harass California sea 
lions, Pacific harbor seals, and gray whales that may be swimming, 
foraging, or resting in the project vicinity.
    As indicated by monitoring elsewhere, the use of vibratory hammers 
for installing sheet-pile sections for the dam and the vibratory 
driver/extractor used to install and remove temporary piles are not 
expected to produce noise levels sufficient to result in a significant 
behavioral response in pinnipeds.
    During the 2-month PIDP construction period, sound measurements 
were taken during pile driving of three piles, and marine mammals were 
monitored at the project site and at the harbor seal haul-out site on 
YBI. Results of observable effects of the PIDP on marine mammals have 
been summarized previously in this document and also provided in the 
Marine Mammal Impact Assessment Report prepared by CALTRANS in August 
2001 (CALTRANS 2001). More specifically, the demonstration provided 
CALTRANS an opportunity to measure resulting SPLs both in air and under 
water, record impacts to marine mammals and experiment with measures to 
reduce harm to marine mammals. Sixty-eight pinnipeds (55 harbor seals 
and 13 sea lions) were sighted during monitoring activities. Of this 
total, 57 pinnipeds (47 harbor seals and 10 sea lions) were seen during 
non-pile driving activities. Only eight harbor seals and three sea 
lions were observed near the PIDP site during actual pile driving, 
which totaled 12 hours and 51 minutes. In addition, up to 85 harbor 
seals per monitoring period hauled out at the semi-protected cove on 
the southwestern side of YBI, approximately 1,500 m (4,920 ft) from the 
pile-driving area. No gray whales were observed.
    The East Span Project is not expected to result in any significant 
impacts to marine mammal habitat. Short-term impacts will include the 
minimal disturbance of the sediment where the channels are dredged for 
barge access and where individual bridge piers are constructed. Long-
term impacts to marine mammal habitat will be limited to the footprint 
of the piles and the obstruction they will create following 
installation. However, this impact is not considered significant as the 
marine mammals can easily swim around the piles of the new bridge, as 
they currently swim around the existing bridge piers.

California Sea Lions

    Of the 13 total sea lions observed during the PIDP construction 
period, three individual sea lions were observed in the PIDP 
construction site within and beyond the 500-m (1,640-ft) safety zone 
during the actual driving of piles. The three sea lions rapidly swam 
and porpoised out of the area when pile driving began, indicating 
possibly: (1) increased sensitivity to the pile driving noise in air 
and/or water, (2) less conditioning to anthropogenic noise, or (3) a 
difference of the level of sound received by the sea lions resulting 
from varying human, environmental (ambient) and hammer magnitude or 
conditions at the time of pile driving. Alternatively, since the three 
sea lions were present at the start of pile driving, their response 
could indicate that they were startled by the noise (SRS Technologies, 
2001). The frequency and duration of the noise and whether underwater 
or airborne sounds start suddenly or gradually, creating a ramping 
effect (as usually performed for the PIDP), may also influence the 
behavior of these mammals. However, none of these factors could be 
explored in detail within the scope of the demonstration project.
    Noise levels from the East Span project are not expected to result 
in harassment of the sea lions hauled out at Pier 39 as airborne and 
waterborne SPLs would attenuate to below harassment levels by the time 
they reach the haul-out site, 5.7 kilometers (3.5 miles) from the 
project site.

Pacific Harbor Seals

    The Richmond Bridge Harbor Seal Survey continues to gather data on 
harbor seals at the Castro Rocks and YBI

[[Page 64606]]

haul-out sites as part of the San Rafael-Richmond Bridge Seismic 
Retrofit Project monitoring program (see 66 FR 49165, September 26, 
2001, 67 FR 61323, September 30, 2002). A total of 55 harbor seals were 
observed in the vicinity of the PIDP site during the 2 1/2-month 
construction period. Of this total, 47 were observed during non-pile 
driving activities and eight harbor seals were observed during actual 
pile driving. The eight harbor seals, which were sighted within the 500 
m (1,640 ft) safety zone, seemed to observe the activities around the 
barge during pile driving while swimming in and out of the safety zone, 
but did not show any avoidance response during pile driving. Additional 
observations during the PIDP showed that harbor seals at YBI increased 
in number during low tide, and responded to activities unrelated to 
pile driving activities such as helicopter noise, boat traffic and 
kayakers, with head alerts or flushing of the site when startled or 
disturbed.
    Pile driving could potentially harass those harbor seals that are 
in the water close to the project site, whether their heads are above 
or below the surface. Since no response was observed from harbor seals 
in the water at YBI during the PIDP except for initial reaction from 
airborne noise during driving of unattenuated Segment A of Pile 1, it 
is likely that underwater SPLs resulting from pile driving activity at 
a distance of about 1,500 m (4,920 ft) or greater would be sufficiently 
attenuated at the haul-out site. It is estimated that only a fraction 
of the seals hauled out at YBI would potentially be in the water and 
close to the project site during pile driving activities.
    The impact of land-based pile-driving activities have been 
evaluated with respect to airborne noise generated by the PIDP. During 
the PIDP, driving Pile 1D generated an SPL of 97 dBA (Lmax-fast) at a 
distance of 100 m (328 ft). The noise level at 30.5 m (100 ft) for this 
pile was calculated to be 110 dBA. This was assumed to be the loudest 
section of the entire pile and similar results were obtained for other 
piles at similar distances. Measurements at Treasure Island (about 
1,400 m (4593 ft) from pile driving) and the YBI Coast Guard Station 
(about 1,350 m (4429 ft), indicated the loudest noise levels were about 
68 to 69 dBA. Modeling indicates that noise levels at the YBI haulout 
from the PIDP would have amaximum A-weighted noise level of 63 dBA 
(Lmax-fast). CALTRANS measured ambient noise conditions near the 
haulout and found typical noise levels to be about 60 to 65 dBA, due to 
existing traffic on the West Span of the Bridge. Therefore, noise 
levels generated by the PIDP would have been audible to harbor seals, 
but would be significantly less than the 90 dBA SPL presumed to cause 
harbor seal beach flushing as recorded on San Nicolas Island, CA (see 
68 FR 52132, September 2, 2003).
    Typical land-based pile driving are expected to produce a noise 
level of 100 dBA at 31 m (100 ft). Land-based piles could be driven at 
distances of 300 to 700 m (984 to 2296 ft) from the haul-out site. 
However, there is not a direct acoustic path from the site to the 
haulout. As a result, modeling indicates that noise levels from the 
land-based pile driving would be 60 dBA or less (i.e., lower than 
typical ambient) and therefore would not result in incidental 
harassment.
    As a result, potential harassment would be expected only during 
those times when in-Bay piles are being hammered, which will be a total 
of approximately 1,300 hours over the 9-year construction period. The 
number of harbor seals that could potentially be harassed during the 
East Span Project therefore would vary based on the location of pile 
driving activity and the proximity of the in-water seals to the pile 
driving site.
    Finally, it should be noted that harbor seals on the YBI haul-out 
site are commonly subjected to high levels of disturbance, primarily 
from water craft. This is particularly true during the summer, when the 
numbers of small boats, jet skis, kayaks, etc., in the Bay increase 
(San Francisco State University, 1999b). Abandonment or disturbance of 
the YBI haul-out site is not anticipated as low-energy sound levels 
from pile driving, both in water and in air, are expected to attenuate 
sufficiently by the time they reach the site. Although harbor seal pups 
have been observed at the YBI haul-out site, it is not a recognized 
pupping site. Therefore, no impact on species recruitment or survival 
are anticipated.

Gray Whales

    No gray whales were observed during the PIDP. However, gray whales 
can be expected in the Bay in increasing numbers from December through 
May during their winter migration to and from Alaska. Noise from the 
pile driving activities therefore may affect gray whales swimming 
toward the southern San Bruno Shoals region.
    Behavioral responses of gray whales to noise can include avoidance, 
startle response, and complete abandonment of an area. Noise may elicit 
short-term disruptions of normal activities similar to seals, such as 
startle response, agitation, stress, and cessation of foraging 
activities. Most evidence suggests that whales will avoid loud noises, 
which may result in a temporary displacement of the animal from typical 
foraging or traveling areas. Although it is uncertain whether gray 
whales will be affected by SPLs generated by pile driving during the 
East Span Project, observations and research from the past 3 years 
(1999-2001) indicate that fewer than 10 gray whales have been sighted 
in the Bay on any particular day (Oliver personal communication, 2001). 
The number of gray whales present in the Bay may increase in the 
future, since in recent years there have been more frequent sightings 
of gray whales in the Bay during their migration period. Whether these 
whales will be in close proximity to the construction area for any 
period of time is unknown at this time. The primary concern is for 
whales passing by YBI on the west or east sides while traveling to San 
Bruno Shoals.

Mitigation

Barrier Systems

    A bubble curtain system is required to be used only when driving 
the permanent in-Bay piles. While the bubble curtain is required 
specifically as a method to reduce impacts to endangered and threatened 
fish species in SFB, it may also provide some benefit for marine 
mammals. The NMFS' Biological Opinion and the California Department of 
Fish and Game's (CDFG) 2001 Incidental Take Permit also allow for the 
use of other equally effective methods, such as cofferdams, as an 
alternative to the air bubble curtain system to attenuate the effects 
of sound pressure waves on fish during driving of permanent in-Bay 
piles (NMFS 2001; CDFG, 2001). Piers E-16 through E-7 for both the 
eastbound and westbound structures of the Skyway will be surrounded by 
sheet-pile cofferdams, which will be dewatered before the start of 
pile-driving. De-watered cofferdams are effective sound attenuation 
devices. For Piers E3 through E6 of the Skyway and Piers 1 and E2 of 
the Self-Anchored Suspension span, it is anticipated that cofferdams 
will not be used: therefore, a bubble curtain will surround the piles.

Sound Attenuation

    As a result of the determinations made during the PIDP restrike and 
the investigation at the Benicia-Martinez Bridge, NMFS has determined 
that CALTRANS must install an air bubble curtain for pile driving for 
the in-Bay piles without cofferdams located at the SF-OBB. This air 
bubble curtain system will consist of concentric layers of perforated 
aeration pipes stacked

[[Page 64607]]

vertically and spaced no more than five vertical meters apart in all 
tide conditions. The minimum number of layers must be in accordance 
with water depth at the subject pile: 0-<5 m = 2 layers (1263 cfm); 5-
<10 m = 4 layers (2526 cfm), 10-<15 m = 7 layers (4420 cfm); 15-<20 m = 
10 layers (6314 cfm); 20-<25 m= 13 layers (8208 cfm). The lowest layer 
of perforated aeration pipes must be designed to ensure contact at all 
times and tidal conditions with the mudline without sinking into the 
bay mud. Pipes in any layer must be arranged in a geometric pattern, 
which will allow for the pile driving operation to be completely 
enclosed by bubbles for the full depth of the water column.
    To provide a uniform bubble flux, each aeration pipe must have four 
adjacent rows of air holes along the pipe. Air holes must be 1.6-mm 
diameter air holes spaced approximately 20 mm apart. The bubble curtain 
system will provide a bubble flux of at least two cubic meters per 
minute, per linear meter of pipeline in each layer. Air holes must be 
placed in 4 adjacent rows.
    The air bubble curtain system must be composed of the following: 
(1) an air compressor(s), (2) supply lines to deliver the air, (3) 
distribution manifolds or headers, (4) perforated aeration pipes, and 
(5) a frame. The frame facilitates transport and placement of the 
system, keeps the aeration pipes stable, and provides ballast to 
counteract the buoyancy of the aeration pipes in operation. Meters are 
required to monitor the operation of the bubble curtain system. 
Pressure meters will be installed at all inlets to aeration pipelines 
and at points of lowest pressure in each branch of the aeration 
pipeline. Flow meters will be installed in the main line at each 
compressor and at each branch of the aeration pipelines at each inlet. 
Gauges will be installed above the water line at the supply barge for 
engineer's access. A manual recording device will be used to plot 
variations in meter readings every 30 minutes. If the pressure or flow 
rate in any meter falls below 90 percent of its operating value, the 
contractor will cease pile-driving operations until the problem is 
corrected and the system is tested to the satisfaction of the CALTRANS 
resident engineer.

Establishment of Safety/Buffer Zones

    A safety zone is to be established and monitored to include all 
areas where the underwater SPLs are anticipated to equal or exceed 190 
dB re 1 microPa RMS (impulse) for pinnipeds. Also, a 180-dB re 1 
microPa RMS (impulse) safety zone for gray whales must be established 
for pile driving occurring during the gray whale migration season from 
December through May. Prior to commencement of any pile driving, a 
preliminary 500-m (1,640-ft) radius safety zone for pinnipeds 
(California sea lions and Pacific harbor seals) will be established 
around the pile driving site, as it was for the PIDP. Once pile driving 
begins, either new safety zones can be established for the 500 kJ and 
1700 kJ hammers or the 500 m (1,640 ft) safety zone can be retained. If 
new safety zones are established based on SPL measurements, NMFS 
requires that each new safety zone be based on the most conservative 
measurement (i.e., the largest safety zone configuration). SPLs will be 
recorded at the 500-m (1,640-ft) contour. The safety zone radius for 
pinnipeds will then be enlarged or reduced, depending on the actual 
recorded SPLs.
    Observers on boats will survey the safety zone to ensure that no 
marine mammals are seen within the zone before pile driving of a pile 
segment begins. If marine mammals are found within the safety zone, 
pile driving of the segment will be delayed until they move out of the 
area. If a marine mammal is seen above water and then dives below, the 
contractor will wait 15 minutes and if no marine mammals are seen by 
the observer in that time it will be assumed that the animal has moved 
beyond the safety zone. This 15-minute criterion is based on scientific 
evidence that harbor seals in San Francisco Bay dive for a mean time of 
0.50 minutes to 3.33 minutes (Harvey and Torok, 1994). However, due to 
the limitations of monitoring from a boat, there can be no assurance 
that the zone will be devoid of all marine mammals at all times.
    Once the pile driving of a segment begins it cannot be stopped 
until that segment has reached its predetermined depth due to the 
nature of the sediments underlying San Francisco Bay. If pile driving 
stops and then resumes, it would potentially have to occur for a longer 
time and at increased energy levels. In sum, this would simply amplify 
impacts to marine mammals, as they would endure potentially higher SPLs 
for longer periods of time. Pile segment lengths and wall thickness 
have been specially designed so that when work is stopped between 
segments (but not during a single segment), the pile tip is never 
resting in highly resistant sediment layers. Therefore, because of this 
operational situation, if seals or sea lions enter the safety zone 
after pile driving of a segment has begun, pile driving will continue 
and marine mammal observers will monitor and record marine mammal 
numbers and behavior.

Compliance with Equipment Noise Standards

    To mitigate noise levels and, therefore, impacts to California sea 
lions, Pacific harbor seals, and gray whales, all construction 
equipment will comply as much as possible with applicable equipment 
noise standards of the U.S. Environmental Protection Agency, and all 
construction equipment will have noise control devices no less 
effective than those provided on the original equipment.

Soft Start

    It should be recognized that although marine mammals will be 
protected from Level A harassment by establishment of an air-bubble 
curtain and marine mammal observers monitoring a 190-dB safety zone for 
pinipeds and 180-dB safety zone for gray whales, mitigation may not be 
100 percent effective at all times in locating marine mammals. 
Therefore, in order to provide additional protection to marine mammals 
near the project area by allowing marine mammals to vacate the area 
prior to receiving a potential injury, CALTRANS will also ``soft 
start'' the hammer prior to operating at full capacity. A ``soft 
start'' occurs when the hammer's initial single strikes occur at 10 
second intervals for 3-5 minutes, an action which produces 
approximately 50 percent of the maximum in-air noise level, or 45-55 dB 
(re 20 microPascal-m). Similar levels of noise reduction is expected 
underwater. Therefore, contractor will initiate hammering of both the 
500-kJ and the 1,700-kJ hammers with this procedure in order to allow 
pinnipeds in the area to voluntarily move from the area and should 
expose fewer animals to loud sounds both underwater and above water 
noise. This would also ensure that, although not expected, any 
pinnipeds that are missed during safety zone monitoring will not be 
injured.

Monitoring

Visual Observations

    Safety zone monitoring will be conducted during driving of all in-
Bay, permanent piles without cofferdams. In addition, area-wide 
baseline monitoring will be conducted prior to commencement of work 
that has a potential to result in marine mammal harassment. Monitoring 
of the pinniped and cetacean safety zones will be conducted by a 
minimum of three qualified NMFS-approved observers for each safety 
zone. One three-observer team will be required for the safety zones 
around each pile-driving site, so that multiple teams will be required 
if

[[Page 64608]]

pile-driving is occurring at multiple locations at the same time. The 
observers will begin monitoring at least 30 minutes prior to startup of 
the pile driving. Observers will likely conduct the monitoring from 
small boats, as observations from a higher vantage point (such as the 
SF-OBB) may not be practical. Pile driving will not begin until the 
safety zone is clear of marine mammals. However, as described in the 
Mitigation section, once pile driving of a segment begins, operations 
will continue uninterrupted until the segment has reached its 
predetermined depth. Monitoring will continue through the pile-driving 
period and will end approximately 30 minutes after pile-driving has 
been completed.
    Biological observations will be made using binoculars during 
daylight hours. In addition to monitoring from boats, monitoring of the 
YBI haul-out may be conducted during open-water pile driving activity, 
in coordination with the Richmond Bridge Harbor Seal survey team. At 
least one control site (harbor seal haul-out sites and the waters 
surrounding such sites not impacted by the East Span Project's pile 
driving activities, i.e. Mowry Slough) will be designated and monitored 
for comparison. Monitoring will be conducted twice a week at both YBI 
and the control site. Data on all observations will be recorded and 
will include items such as species, numbers, behavior, details of any 
observed disturbances, time of observation, location, and weather. The 
reactions of marine mammals will be recorded based on the following 
classifications (consistent with the Richmond Bridge Harbor Seal survey 
methodology): (1) no response, (2) head alert (looks toward the source 
of disturbance), (3) approach water (but not leave), and (4) flush 
(leaves haul-out site). The number of marine mammals under each 
disturbance reaction will be recorded, as well as the time when seal 
re-haul after a flush.
    Baseline monitoring will be conducted for a period of 14 days prior 
to the beginning of in-Bay work for the Skyway contract. Baseline 
monitoring will be conducted in the general project area (before pile 
driving begins) and at the YBI haul-out site. The 14-day monitoring 
period is expected to be an appropriate time frame to assess baseline 
conditions in the project area and to account for the potential 
variability in environmental factors that may influence the presence 
and activity of marine mammals. The information collected from baseline 
monitoring will be compared with results from monitoring during pile-
driving activities.
    Aerial surveys will be conducted during the baseline monitoring to 
help determine if the boat observers are missing any marine mammals 
within a simulated safety zone. A fixed-wing airplane equipped with a 
high-resolution camera will take five photos of the safety zone (about 
1 km\2\ or 0.3 mi\2\) and the surrounding area (about 4 km\2\ or 1.5 
mi\2\) from each of three aircraft elevations (610 m/2000 ft, 305 m/
1000 ft and 152 m/500 ft).
    It is anticipated that installation of small, temporary piles for 
the temporary structures at each of the piers and for the temporary 
trestles near the Oakland Touchdown area will not affect marine mammals 
in the area, since a vibratory hammer will be used with energy levels 
less than 100 kJ. To verify this assumption, marine mammal monitoring 
will be conducted when driving the temporary in-Bay piles at Pier E16E, 
during the start of the Skyway contract. Based on the results of these 
initial observations, CALTRANS will consult with NMFS to confirm that 
further monitoring when driving temporary piles will not be needed or 
to develop an appropriate program for further monitoring temporary 
piles.

Acoustical Observations

    Both airborne and underwater environmental noise levels will be 
measured as part of the East Span Project.
    The purpose of the underwater sound monitoring is to establish the 
safety zone of 190 dB re 1 micro-Pa RMS (impulse) for pinnipeds and the 
safety zone of 180 dB re 1 micro-Pa RMS (impulse) for gray whales. 
Monitoring will be conducted during the driving of the last half 
(deepest pile segment) for any given in-Bay pile. One pile in every 
other pair of pier groups will be monitored. One reference location 
will be established at a distance of 100 m (328 ft) from the pile 
driving. Sound measurements will be taken at the reference location at 
two depths (a depth near the mid-water column and a depth near the 
bottom of the water column but at least 1 m (3 ft) above the bottom) 
during the driving of the last half (deepest pile segment) for any 
given pile. Two additional in-water spot measurements will be conducted 
at appropriate depths (near mid water column), generally 500 m (1,640 
ft) in two directions either west, east, south or north of the pile-
driving site will be conducted at the same two depths as the reference 
location measurements. In cases where such measurements cannot be 
obtained due to obstruction by land mass, structures or navigational 
hazards, measurements will be conducted at alternate spot measurement 
locations. Measurements will be made at other locations either nearer 
or farther as necessary to establish the approximate distance for the 
safety zones. Each measuring system shall consist of a hydrophone with 
an appropriate signal conditioning connected to a sound level meter and 
an instrument grade digital audiotape recorder (DAT). Overall SPLs 
shall be measured and reported in the field in dB re 1 micro-Pa RMS 
(impulse). An infrared range finder will be used to determine distance 
from the monitoring location to the pile. The recorded data will be 
analyzed to determine the amplitude, time history and frequency content 
of the impulse.
    Airborne sound levels will be measured at times and locations that 
are coincidental to the underwater measurement sites. Each system will 
consist of a type 1 integrating sound level meter connected to a DAT. 
In addition, airborne sound will also be measured at the YBI haul-out 
site. Real time amplitude measurement of airborne sound levels will be 
reported. Linear Peak and RMS impulse SPLs will be reported. 
Microphones will be fitted with windscreens and calibration will be 
verified before and after each measurement session. The recorded data 
will be analyzed to determine the amplitude, time history and frequency 
content of the impulse.

Reporting

    NMFS' Southwest Regional Administrator will be notified prior to 
the initiation of the East Span Project, and coordination with NMFS 
will occur on a weekly basis, or more often as necessary. NMFS will be 
informed of the initial SPL measurements taken at the 500-m (1,640-ft) 
contour and the final safety-zone radius established. Monitoring 
reports will be faxed to NMFS on a monthly basis during open-water pile 
driving activity. The monthly report will include a summary of the 
previous month's monitoring activities and an estimate of the number of 
seals and sea lions that may have been disturbed as a result of pile 
driving activities.
    Because the East Span Project is expected to continue beyond the 
date of expiration of this IHA (under a new IHA or under regulations 
pursuant to section 101(a)(5)(A) of the MMPA), CALTRANS will provide 
NMFS' Southwest Regional Administrator with a draft final report before 
90 days after expiration of this IHA. This report should detail the 
monitoring protocol, summarize the data recorded during monitoring, and 
estimate the number of marine mammals that may have been harassed

[[Page 64609]]

due to pile driving. If comments are received from the Regional 
Administrator on the draft final report, a final report must be 
submitted to NMFS within 30 days thereafter. If no comments are 
received from NMFS, the draft final report will be considered to be the 
final report.

National Environmental Policy Act (NEPA)

    NMFS has prepared an EA and made a Finding of No Significant Impact 
(FONSI). Therefore, preparation of an environmental impact statement on 
this action is not required by section 102(2) of the NEPA or its 
implementing regulations. A copy of the EA and FONSI are available upon 
request (see ADDRESSES).

Endangered Species Act (ESA)

    On October 30, 2001, NMFS completed consultation under section 7 of 
the ESA with the FHWA on the CALTRANS' construction of a replacement 
bridge for the East Span of the SF-OBB in California. The finding 
contained in the Biological Opinion was that the proposed action at the 
East Span of the SF-OBB is not likely to jeopardize the continued 
existence of listed anadromous salmonids, or result in the destruction 
or adverse modification of designated critical habitat for these 
species. Listed marine mammals are not expected to be in the area of 
the action and thus would not be affected. However, issuance of this 
IHA to CALTRANS constitutes an agency action that authorizes an 
activity that may affect ESA-listed species and, therefore, is subject 
to section 7 of the ESA. However, as the effects of the activities on 
listed salmonids were analyzed during a formal consultation between the 
FHWA and NMFS, and as the underlying action has not changed from that 
considered in the consultation, the discussion of effects that are 
contained in the Biological Opinion issued to the FHWA on October 30, 
2001, pertains also to this action. In conclusion, NMFS has determined 
that issuance of an IHA does not lead to any effects to listed species 
apart from those that were considered in the consultation on FHWA's 
action.

Determinations

    For the reasons discussed in detail in this document, NMFS has 
determined that the impact of pile driving and other activities 
associated with construction of the East Span Project, (described in 
this document), should result, at worst, in the Level B harassment of 
small numbers of California sea lions, Pacific harbor seals and 
potentially gray whales that inhabit or visit SFB in general and the 
vicinity of the SF-OBB in particular. While behavioral modifications, 
including temporarily vacating the area around the construction site, 
may be made by these species to avoid the resultant visual and acoustic 
disturbance, the availability of alternate areas within SFB and its 
haul-out sites (including pupping sites) and feeding areas within the 
Bay has led NMFS to determine that this action will have a negligible 
impact on California sea lion, Pacific harbor seal, and gray whale 
populations along the California coast.
    In addition, no take by level A harassment (injury) or death is 
anticipated and harassment takes should be at the lowest level 
practicable due to incorporation of the mitigation measures mentioned 
previously in this document.

Authorization

    For the reasons previously discussed, NMFS has issued an IHA for a 
1-year period, for the incidental harassment of harbor seals, 
California sea lions and California gray whales by the construction of 
a replacement bridge for the East Span of the San Francisco-Oakland Bay 
Bridge in California, provided the previously mentioned mitigation, 
monitoring and reporting requirements are incorporated.

    November 4, 2003.
Laurie K. Allen,
Acting Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. 03-28549 Filed 11-13-03; 8:45 am]
BILLING CODE 3510[dash]22[dash]S