2024-18146. Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental To Ferndale Refinery Dock Maintenance and Pile Replacement Activities in Ferndale, Washington

Table 2—Species for Which Take Could Occur in the Project Area

Common name	Scientific name	Stock	ESA/MMPA status; Strategic (Y/N) 1	Stock abundance (CV, Nmin, most recent abundance survey) 2	PBR	Annual M/SI3 3
Order Artiodactyla—Cetacea—Mysticeti (baleen whales)
Family Balaenopteridae (rorquals):
Humpback Whale	Megaptera novaeangliae	Central America/Southern Mexico—CA/OR/WA	E, D, Y	1,494 (0.171, 1,284, 2021)	3.5	14.9
Humpback Whale	Megaptera novaeangliae	Mainland Mexico—CA/OR/WA	T, D, Y	3,477 (0.101, 3,185, 2018)	43	22
Humpback Whale	Megaptera novaeangliae	Hawaii	-, -, N	11,278 (0.56, 7,265, 2020)	127	27.09
Odontoceti (toothed whales, dolphins, and porpoises)
Family Delphinidae:
Killer Whale	Orcinus orca	Eastern North Pacific Southern Resident	E, D, Y	73 (N/A, 73, 2022)	0.13	0
Killer Whale	Orcinus orca	West Coast Transient	-, -, N	349 (N/A, 349, 2018)	3.5	0.4
Family Phocoenidae (porpoises):
Harbor porpoise	Phocoena phocoena	Washington Inland Waters	-, -, N	11,233 (0.37, 8,308, 2015)	66	≥7.2
Order Carnivora—Pinnipedia
Family Otariidae (eared seals and sea lions):
California Sea Lion	Zalophus californianus	U.S.	-,-; N	257,606 (N/A, 233,515, 2014)	14,011	>321
Steller Sea Lion	Eumetopias jubatus	Eastern	-,-; N	36,308 (N/A, 36,308, 2022)	2,178	93.2
Family Phocidae (earless seals):
( print page 66059)
Harbor Seal	Phoca vitulina	Washington Northern Inland Waters	-, -, N	16,451 (0.07, 15,462, 2019)	928	40
1  Information on the classification of marine mammal species follows The Society for Marine Mammalogy's Committee on Taxonomy ( https://www.marinemammalscience.org/​science-and-publications/​list-marine-mammal-species-subspecies/​). ESA status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
2  NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/​national/​marine-mammal-protection/​marine-mammal-stock-assessments. CV is coefficient of variation; N min is the minimum estimate of stock abundance. In some cases, CV is not applicable.
3  These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined ( e.g., commercial fisheries, vessel strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range.

Marine Mammal Hearing

Hearing is the most important sensory modality for marine mammals underwater, and exposure to anthropogenic sound can have deleterious effects. To appropriately assess the potential effects of exposure to sound, it is necessary to understand the frequency ranges marine mammals are able to hear. Not all marine mammal species have equal hearing capabilities ( e.g., Richardson et al., 1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al. (2007, 2019) recommended that marine mammals be divided into hearing groups based on directly measured (behavioral or auditory evoked potential techniques) or estimated hearing ranges (behavioral response data, anatomical modeling, etc.). Note that no direct measurements of hearing ability have been successfully completed for mysticetes ( i.e., low-frequency cetaceans). Subsequently, NMFS (2018) described generalized hearing ranges for these marine mammal hearing groups. Generalized hearing ranges were chosen based on the approximately 65 decibel (dB) threshold from the normalized composite audiograms, with the exception for lower limits for low-frequency cetaceans where the lower bound was deemed to be biologically implausible and the lower bound from Southall et al. (2007) retained. Marine mammal hearing groups and their associated hearing ranges are provided in table 3.

Table 3—Marine Mammal Hearing Groups

[NMFS, 2018]

Hearing group	Generalized hearing range *
Low-frequency (LF) cetaceans (baleen whales)	7 Hz to 35 kHz.
Mid-frequency (MF) cetaceans (dolphins, toothed whales, beaked whales, bottlenose whales)	150 Hz to 160 kHz.
High-frequency (HF) cetaceans (true porpoises, Kogia, river dolphins, Cephalorhynchid, Lagenorhynchus cruciger & L. australis)	275 Hz to 160 kHz.
Phocid pinnipeds (PW) (underwater) (true seals)	50 Hz to 86 kHz.
Otariid pinnipeds (OW) (underwater) (sea lions and fur seals)	60 Hz to 39 kHz.
* Represents the generalized hearing range for the entire group as a composite ( i.e., all species within the group), where individual species' hearing ranges are typically not as broad. Generalized hearing range chosen based on ~65 dB threshold from normalized composite audiogram, with the exception for lower limits for LF cetaceans (Southall et al. 2007) and PW pinniped (approximation).

The pinniped functional hearing group was modified from Southall et al. (2007) on the basis of data indicating that phocid species have consistently demonstrated an extended frequency range of hearing compared to otariids, especially in the higher frequency range (Hemilä et al., 2006; Kastelein et al., 2009; Reichmuth et al., 2013).

For more detail concerning these groups and associated frequency ranges, please see NMFS (2018) for a review of available information.

Potential Effects of Specified Activities on Marine Mammals and Their Habitat

The effects of underwater noise from Phillip's 66 dock replacement activities have the potential to result in behavioral harassment of marine mammals in the vicinity of the southeastern shores of the Strait of Georgia, in Puget Sound WA. The notice of proposed IHA (89 FR 53046, June 25, 2024) included a discussion of the effects of anthropogenic noise on marine mammals and the potential effects of underwater noise from vibratory pile driving on marine mammals and their habitat. That information and analysis is referenced in this final IHA determination and is not repeated here; please refer to the notice of proposed IHA (89 FR 53046, June 25, 2024).

Estimated Take of Marine Mammals

This section provides an estimate of the number of incidental takes authorized through the IHA, which informs NMFS' consideration of “small numbers,” the negligible impact determinations, and impacts on subsistence uses.

Harassment is the only type of take expected to result from these activities. Except with respect to certain activities not pertinent here, section 3(18) of the MMPA defines “harassment” as any act of pursuit, torment, or annoyance, which (i) has the potential to injure a marine mammal or marine mammal stock in the wild (Level A harassment); or (ii) has the potential to disturb a marine mammal or marine mammal stock in the wild by causing disruption of behavioral patterns, including, but not limited to, migration, breathing, nursing, breeding, feeding, or sheltering (Level B harassment).

Authorized takes will be by Level B harassment only, as use of the acoustic stressors ( i.e., pile driving) has the potential to result in disruption of behavioral patterns for individual marine mammals. The mitigation and monitoring measures are expected to minimize the severity of the taking to the extent practicable. ( print page 66060)

As described previously, no serious injury or mortality is anticipated or authorized for this activity. Below we describe how the take numbers are estimated.

For acoustic impacts, generally speaking, we estimate take by considering: (1) acoustic thresholds above which NMFS believes the best available science indicates marine mammals will be behaviorally harassed or incur some degree of permanent hearing impairment; (2) the area or volume of water that will be ensonified above these levels in a day; (3) the density or occurrence of marine mammals within these ensonified areas; and (4) the number of days of activities. We note that while these factors can contribute to a basic calculation to provide an initial prediction of potential takes, additional information that can qualitatively inform take estimates is also sometimes available ( e.g., previous monitoring results or average group size). Below, we describe the factors considered here in more detail and present the take estimates.

Acoustic Thresholds

NMFS recommends the use of acoustic thresholds that identify the received level of underwater sound above which exposed marine mammals will be reasonably expected to be behaviorally harassed (equated to Level B harassment).

Level B Harassment —Though significantly driven by received level, the onset of behavioral disturbance from anthropogenic noise exposure is also informed to varying degrees by other factors related to the source or exposure context ( e.g., frequency, predictability, duty cycle, duration of the exposure, signal-to-noise ratio, distance to the source), the environment ( e.g., bathymetry, other noises in the area, predators in the area), and the receiving animals (hearing, motivation, experience, demography, life stage, depth) and can be difficult to predict ( e.g., Southall et al., 2007, 2021; Ellison et al., 2012). Based on what the available science indicates and the practical need to use a threshold based on a metric that is both predictable and measurable for most activities, NMFS typically uses a generalized acoustic threshold based on received level to estimate the onset of behavioral harassment. NMFS generally predicts that marine mammals are likely to be behaviorally harassed in a manner considered to be Level B harassment when exposed to underwater anthropogenic noise above root-mean-squared pressure received levels (RMS SPL) of 120 dB (referenced to 1 micropascal (re 1 μPa)) for continuous ( e.g., vibratory pile driving, drilling) and above RMS SPL 160 dB (re 1 μPa) for non-explosive impulsive ( e.g., seismic airguns) or intermittent ( e.g., scientific sonar) sources. Generally speaking, Level B harassment take estimates based on these behavioral harassment thresholds are expected to include any likely takes by TTS as, in most cases, the likelihood of TTS occurs at distances from the source less than those at which behavioral harassment is likely. TTS of a sufficient degree can manifest as behavioral harassment, as reduced hearing sensitivity and the potential reduced opportunities to detect important signals (conspecific communication, predators, prey) may result in changes in behavior patterns that would not otherwise occur.

The Phillips 66 activity includes the use of continuous sound sources (vibratory driving), and therefore the RMS SPL threshold of 120 dB re 1 μPa is applicable.

These thresholds are provided in the table 4 below. The references, analysis, and methodology used in the development of the thresholds are described in NMFS' 2018 Technical Guidance, which may be accessed at: https://www.fisheries.noaa.gov/​national/​marine-mammal-protection/​marine-mammal-acoustic-technical-guidance.

Table 4—Thresholds Identifying the Onset of Permanent Threshold Shift

Hearing group	PTS onset acoustic thresholds * (received level)
	Impulsive	Non-impulsive
Low-Frequency (LF) Cetaceans	Cell 1:Lpk,flat : 219 dB; LE,LF,24h : 183 dB	Cell 2:LE,LF,24h : 199 dB.
Mid-Frequency (MF) Cetaceans	Cell 3:Lpk,flat : 230 dB; LE,MF,24h : 185 dB	Cell 4:LE,MF,24h : 198 dB.
High-Frequency (HF) Cetaceans	Cell 5:Lpk,flat : 202 dB; LE,HF,24h : 155 dB	Cell 6:LE,HF,24h : 173 dB.
Phocid Pinnipeds (PW) (Underwater)	Cell 7:Lpk,flat : 218 dB; LE,PW,24h : 185 dB	Cell 8:LE,PW,24h : 201 dB.
Otariid Pinnipeds (OW) (Underwater)	Cell 9:Lpk,flat : 232 dB; LE,OW,24h : 203 dB	Cell 10:LE,OW,24h : 219 dB.
* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level thresholds associated with impulsive sounds, these thresholds should also be considered.
Note: Peak sound pressure ( Lpk ) has a reference value of 1 μPa, and cumulative sound exposure level ( LE ) has a reference value of 1μPa2 s. In this table, thresholds are abbreviated to reflect American National Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI as incorporating frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript “flat” is being included to indicate peak sound pressure should be flat weighted or unweighted within the generalized hearing range. The subscript associated with cumulative sound exposure level thresholds indicates the designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds) and that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds could be exceeded in a multitude of ways ( i.e., varying exposure levels and durations, duty cycle). When possible, it is valuable for action proponents to indicate the conditions under which these acoustic thresholds will be exceeded.

Ensonified Area

Here, we describe operational and environmental parameters of the activity that are used in estimating the area ensonified above the acoustic thresholds, including source levels and TL coefficient.

The sound field in the project area is the existing background noise plus additional construction noise from the project. Marine mammals are expected to be affected via sound generated by the primary components of the project ( i.e., vibratory pile driving). Additionally, vessel traffic and other commercial and industrial activities in the project area may contribute to elevated background noise levels which may mask sounds produced by the project.

TL is the decrease in acoustic intensity as an acoustic pressure wave propagates out from a source. TL parameters vary with frequency, temperature, sea conditions, current, source and receiver depth, water depth, water chemistry, and bottom composition and topography. The general formula for underwater TL is:

TL = B * Log₁₀ (R₁ /R₂),

( print page 66061)

Where:

TL = transmission loss in dB

B = transmission loss coefficient

R₁ = the distance of the modeled SPL from the driven pile, and

R₂ = the distance from the driven pile of the initial measurement

This formula neglects loss due to scattering and absorption, which is assumed to be zero here. The degree to which underwater sound propagates away from a sound source is dependent on a variety of factors, most notably the water bathymetry and presence or absence of reflective or absorptive conditions including in-water structures and sediments. Spherical spreading occurs in a perfectly unobstructed (free-field) environment not limited by depth or water surface, resulting in a 6-dB reduction in sound level for each doubling of distance from the source (20*log[range]). Cylindrical spreading occurs in an environment in which sound propagation is bounded by the water surface and sea bottom, resulting in a reduction of 3 dB in sound level for each doubling of distance from the source (10*log[range]). A practical spreading value of 15 is often used under conditions, such as the project site, where water increases with depth as the receiver moves away from the shoreline, resulting in an expected propagation environment that would lie between spherical and cylindrical spreading loss conditions. Practical spreading loss is assumed here.

The intensity of pile driving sounds is greatly influenced by factors such as the type of piles, hammers, and the physical environment in which the activity takes place. In order to calculate the distances to the Level B harassment sound thresholds for the method and piles being used in this project, NMFS used acoustic monitoring data from other locations to develop proxy source levels for the various pile types, sizes and methods. The project includes vibratory pile installation of 20-in steel piles. Source levels for the pile size and driving method are presented in table 5. The closest representative pile size for reference sound levels was 24-inch piles (WSDOT 2020).

Table 5—Proxy Sound Source Levels for Pile Sizes and Driving Methods

Equipment used	Noise level			Distance from measurement
	dB Peak	dB rms	dB SEL (m)
Vibratory pile driving 24-inch steel piles 1	181	153		10
1  Caltrans 2020.

The ensonified area associated with Level A harassment is more technically challenging to predict due to the need to account for a duration component. Therefore, NMFS developed an optional User Spreadsheet tool to accompany the Technical Guidance that can be used to relatively simply predict an isopleth distance for use in conjunction with marine mammal density or occurrence to help predict potential takes. We note that because of some of the assumptions included in the methods underlying this optional tool, we anticipate that the resulting isopleth estimates are typically going to be overestimates of some degree, which may result in an overestimate of potential take by Level A harassment. However, this optional tool offers the best way to estimate isopleth distances when more sophisticated modeling methods are not available or practical. For stationary sources such as impact or vibratory pile driving and removal, the optional User Spreadsheet tool predicts the distance at which, if a marine mammal remained at that distance for the duration of the activity, it would be expected to incur PTS. Inputs used for impact driving in the optional NMFS User Spreadsheet tool, and the resulting estimated isopleths, are reported below in table 6 and table 7 below.

Table 6—User Spreadsheet Inputs for Level A Harassment Isopleths

Inputs	20-in Steel vibratory installation
Spreadsheet Tab Used	Vibratory Pile Driving (STATIONARY: Non-impulsive, Continuous)
Source Level (Single Strike/shot SEL)
Peak
RMS	153
Weighting Factor Adjustment (kHz)	2.5
Strikes per pile
Piles Per day	16
Propagation (xLogR)	15
Duration	15
Distance of source level measurement (meters)+	10

( print page 66062)

Table 7—Calculated Level A and Level B Harassment Isopleths ( m ) and Ensonified Areas

[ km² in parentheses]

Pile size/type	Level A pinnipeds		Level A cetaceans			Level B
	Harbor seal	Sea lions	LF	MF	HF
Vibratory Installation						120 dB threshold
20-in steel	3.1 (.003)	<1 (.000)	5 (.005)	<1 (.000)	7.5 (.007)	1585 (1.5)
* The Level A harassment isopleths associated with vibratory installation are all below the minimum shutdown zone and result in very small ensonified areas. Therefore they are not provided in this table but will be included in the following calculated take tables.

Marine Mammal Occurrence and Take Estimation

In this section we provide information about the occurrence of marine mammals, including density or other relevant information which will inform the take calculations. The primary source for density estimates is from the Navy Marine Species Density Database (NMSDD) Phase III for the Northwest Training and Testing Study Area (Navy, 2019). These density estimates are shown in table 8 and will be used to calculate take due to the lack of site-specific data that is available.

To quantitatively assess potential exposure of marine mammals to noise levels from pile driving over the NMFS threshold guidance, the following equation was first used to provide an estimate of potential exposures within estimated harassment zones:

Exposure estimate = N × harassment zone (km² ) × maximum days of pile driving

where

N = density estimate (animals per km² ) used for each species.

Table 8—Marine Mammal Species Densities Used for Exposure Calculations

Species	Region characterized	Density (Animals/km2 )
Humpback Whale	North Puget Sound/San Juan Islands (Fall and Winter)	0.0027
Killer Whale (Southern Resident)	North Puget Sound/San Juan Islands (Fall and Winter)	0.0078
Killer Whale (Transient)	North Puget Sound/San Juan Islands (Fall and Winter)	0.0031
Harbor Porpoise	North Puget Sound	2.16
Steller Sea Lion	North Puget Sound/San Juan Islands (Fall)	0.0027
California Sea Lion	North Puget Sound/San Juan Islands (Fall)	0.0179
Harbor Seal	North Puget Sound/San Juan Islands (Fall)	0.76
Source: Navy 2019.

Potential Level A harassment zones were all calculated to less than 10 meters. As seen from table 7, marine mammals will have to be very close to the vibratory driving activity to be within the estimated Level A harassment zone. Marine mammal monitors will be in place, closely monitoring this zone and stopping work before any marine mammal gets near the largest Level A harassment zone of 6.2m from the project source. Based on the estimated Level A harassment zones, and density-based calculations for all species, no take by Level A Harassment was estimated (all less than 1.0). Harbor porpoise is the species with the highest density at 2.16 per km, multiplied by the Level A harassment zone of .007 km (table 7), and 35 days of work yields 0.53 individuals exposed to Level A harassment. Therefore, when considered in context of planned mitigation, no take by Level A harassment is expected. Table 9 below shows the total calculated take by Level B harassment over the 35 in-water work days planned for the Phillips 66 activity resulting in total calculated take.

Table 9—Calculated and Requested Take by Level B Harassment From Vibratory Pile Installation

35 Days of 20-inch pile installation by vibratory hammer
Species	Total Level B harassment calculated	Level B harassment proposed for authorization
Harbor Porpoise	447	447
Steller Sea Lion	1	35
California Sea Lion	4	105
Harbor Seal	157	157

Humpback Whale

Humpback whales are an uncommon occurrence near the project area but they do have the potential to be in the area as they migrate to feeding grounds to the north and mating grounds far south. Based on best available density estimates, Phillips 66 has calculated the potential take of one humpback whale, by Level B harassment only. However, Phillips 66 proposes to shut down whenever humpback whales approach ( print page 66063) the Level B harassment zone. Given the low density of humpback whales in the project area, the ability to detect the whales visually from a considerable distance, the capacity to track whales through the Orca Network, and the anticipated efficacy of mitigation and monitoring measures, Phillips 66 determined that no take of humpback whales is likely to occur and did not request that any such take be authorized. NMFS concurs with this request and, therefore, has not authorized take of humpback whales.

Killer Whales

Both SRKW and transient killer whales could potentially occur near the project area. Based on best available density estimates, Phillips 66 has calculated that up to two SRKWs and one transient whale could be taken, by Level B harassment only. Even though the project site is located in summer core area critical habitat, and the project may begin August 1, the southeastern corner of the Strait of Georgia (where the project is located) is not a location where SRKW are commonly sighted. According to the monthly ORCA network reports of September through October, from 2016-2023, the occurrence of killer whales from any stock was uncommon in the southeastern corner of the Strait of Georgia. When compared to transient killer whales, sightings of SRKWs were far less prevalent (ORCA 2024). Mitigation requires that pile driving activity shut down whenever a killer whale from any stock is observed approaching a harassment zone. Given the ability to visually detect killer whales from proposed PSO locations (including boats), the capacity to track this species through contact with the ORCA Network, and the expected efficacy of mitigation and monitoring measures, Phillips 66 elected to not request take. Due to the expansive range of SRKWs; the relatively small area of their habitat that may be affected by the project; the ready availability of habitat of similar or higher value, and the short-term nature of installation construction (35 days), Phillips 66 determined that no take of killer whales is likely to occur and did not request that any such take be authorized. NMFS concurs with this request and, therefore, has not authorized take of killer whales.

Steller Sea Lion

Calculated take based upon the species density in the Strait of Georgia yielded one potential take by Level B harassment during the 35 days of in-water pile driving work. While there are no known nearby haulouts, there are haulouts in the greater Strait of Georgia. Phillips 66 determined, based on anecdotal sightings at the facility, that the calculated value was too low. In addition, this species is known to travel significant distances in search for prey, possibly into the surrounding marine waters of the Cherry Point Aquatic Reserve.

NMFS reviewed other IHA monitoring reports from Puget Sound and found that the Seattle Pier 63 construction project (87 FR 31985, May 26, 2022) reported a maximum of one animal present per day over 17 in-water work days between October 12 and November 30, 2022. Therefore, NMFS assumes a similar rate of occurrence and has authorized 35 (one/day) takes of Steller sea lion by Level B harassment.

California Sea Lion

Calculated take based upon the species density in the Strait of Georgia found 4 potential takes by Level B harassment during the 35 days of pile driving work at the Phillips 66 dock. While there are no known nearby haulouts, there are haulouts in the greater Strait of Georgia. Phillips 66 determined, based on anecdotal sightings at the facility, that the calculated value was too low. In addition, this species is known to travel significant distances in search for prey, possibly into the surrounding marine waters of the Cherry Point Aquatic Reserve.

NMFS reviewed other IHA monitoring reports from Puget Sound and found that the Seattle Pier 63 construction project (87 FR 31985, May 26, 2022) reported a maximum of three California sea lions present per day over 17 in-water work days between October 12 and November 30, 2022. Therefore, NMFS assumes a similar rate of occurrence and has authorized 105 (three/day) takes of California sea lions by Level B Harassment.

Details of takes by Level B harassment as a percentage of stocks are shown in table 10.

Table 10—Authorized Take of Marine Mammals by Level B Harassment by Species, Stock, and Percent of Take by Stock

Common name	Stock	Stock abundance	Total authorized take	Authorized take as percentage of stock
Harbor porpoise	Washington Inland Waters	11,233	447	3.97
Steller sea lion	Eastern U.S	36,308	35	0.10
California sea lion	U.S	257,606	105	0.04
Harbor seal	Washington Northern Inland	16,451	157	0.95

Mitigation

In order to issue an IHA under section 101(a)(5)(D) of the MMPA, NMFS must set forth the permissible methods of taking pursuant to the activity, and other means of effecting the least practicable impact on the species or stock and its habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance, and on the availability of the species or stock for taking for certain subsistence uses. NMFS regulations require applicants for incidental take authorizations to include information about the availability and feasibility (economic and technological) of equipment, methods, and manner of conducting the activity or other means of effecting the least practicable adverse impact upon the affected species or stocks, and their habitat (50 CFR 216.104(a)(11)).

In evaluating how mitigation may or may not be appropriate to ensure the least practicable adverse impact on species or stocks and their habitat, as well as subsistence uses where applicable, NMFS considers two primary factors:

(1) The manner in which, and the degree to which, the successful implementation of the measure(s) is expected to reduce impacts to marine mammals, marine mammal species or stocks, and their habitat. This considers the nature of the potential adverse impact being mitigated (likelihood, scope, range). It further considers the likelihood that the measure will be effective if implemented (probability of accomplishing the mitigating result if ( print page 66064) implemented as planned), the likelihood of effective implementation (probability implemented as planned), and;

(2) The practicability of the measures for applicant implementation, which may consider such things as cost, impact on operations.

Pre-start Clearance Monitoring —Prior to the start of daily in-water construction activity, or whenever a break in pile driving/removal of 30 minutes or longer occurs, PSOs would observe the shutdown and monitoring zones for a period of 30 minutes. The shutdown zone would be considered cleared when a marine mammal has not been observed within the zone for that 30-minute period. If a marine mammal is observed within the shutdown zone, a soft-start (discussed below) cannot proceed until the animal has left the zone or has not been observed for 15 minutes. If the monitoring zone has been observed for 30 minutes and marine mammals are not present within the zone, soft-start procedures can commence and work can continue. Pre-start clearance monitoring must be conducted during periods of visibility sufficient for the lead PSO to determine that the shutdown zones, indicated in table 11, are clear of marine mammals. Pile driving may commence following 30 minutes of observation, when the determination is made that the shutdown zones are clear of marine mammals. If work ceases for more than 30 minutes, the pre-activity monitoring of both the monitoring zone and shutdown zone would commence.

Implementation of Shutdown Zones —For all pile driving activities, Phillips 66 would implement shutdowns within designated zones. The purpose of a shutdown zone is generally to define an area within which shutdown of activity would occur upon sighting of a marine mammal (or in anticipation of an animal entering the defined area). Implementation of shutdowns would be used to avoid takes by Level A harassment from vibratory pile driving for all four species for which take may occur.

A minimum shutdown zone of 10 m would be required for all in-water construction activities to avoid physical interaction with marine mammals. Proposed shutdown and monitoring zones for each activity type are shown in table 11.

Table 11—Shutdown Zones During Pile Installation and Removal

[m]

Pile size/type	Shutdown zones			Level B harassment monitoring zone
	HF	Phocid	Otariid
20-in steel Vibratory	10	10	10	1,585