# Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the Replacement of Pier 3 at Naval Station Norfolk in Norfolk, Virginia > Briefs, arguments, decisions, and more. URL: https://www.frixlaw.com/law-library/documents/fr%3A2022-01474 ## Record - **Collection:** Federal Register - **Document type:** Notice - **Published:** January 26, 2022 - **Citation:** 87 FR 3976 ## Text DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration [RTID 0648-XB562] Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the Replacement of Pier 3 at Naval Station Norfolk in Norfolk, Virginia AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION: Notice; proposed incidental harassment authorization; request for comments on proposed authorization and possible renewal. SUMMARY: NMFS has received a request from the United States Department of the Navy (Navy) for authorization to take marine mammals incidental to the replacement of Pier 3 at Naval Station Norfolk in Norfolk, Virginia. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to issue an incidental harassment authorization (IHA) to incidentally take marine mammals during the specified activities. NMFS is also requesting comments on a possible one-time, one-year renewal that could be issued under certain circumstances and if all requirements are met, as described in Request for Public Comments at the end of this notice. NMFS will consider public comments prior to making any final decision on the issuance of the requested MMPA authorizations and agency responses will be summarized in the final notice of our decision. DATES: Comments and information must be received no later than February 25, 2022. ADDRESSES: Comments should be addressed to Jolie Harrison, Chief, Permits and Conservation Division, Office of Protected Resources, National Marine Fisheries Service and should be submitted via email to ITP.Corcoran@noaa.gov. Instructions: NMFS is not responsible for comments sent by any other method, to any other address or individual, or received after the end of the comment period. Comments, including all attachments, must not exceed a 25-megabyte file size. All comments received are a part of the public record and will generally be posted online at www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act without change. All personal identifying information ( e.g., name, address) voluntarily submitted by the commenter may be publicly accessible. Do not submit confidential business information or otherwise sensitive or protected information. FOR FURTHER INFORMATION CONTACT: Kim Corcoran, Office of Protected Resources, NMFS, (301) 427-8401. Electronic copies of the application and supporting documents, as well as a list of the references cited in this document, may be obtained online at: https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act. In case of problems accessing these documents, please call the contact listed above. SUPPLEMENTARY INFORMATION: Background The MMPA prohibits the “take” of marine mammals, with certain exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq. ) direct the Secretary of Commerce (as delegated to NMFS) to allow, upon request, the incidental, but not intentional, taking of small numbers of marine mammals by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region if certain findings are made and either regulations are issued or, if the taking is limited to harassment, a notice of a proposed incidental take authorization may be provided to the public for review. Authorization for incidental takings shall be granted if NMFS finds that the taking will have 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 taking for subsistence uses (where relevant). Further, NMFS must prescribe the permissible methods of taking and other “means of effecting the least practicable adverse impact” on the affected species or stocks and their habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance, and on the availability of the species or stocks for taking for certain subsistence uses (referred to in shorthand as “mitigation”); and requirements pertaining to the mitigation, monitoring and reporting of the takings are set forth. The definitions of all applicable MMPA statutory terms cited above are included in the relevant sections below. National Environmental Policy Act To comply with the National Environmental Policy Act of 1969 (NEPA; 42 U.S.C. 4321 et seq. ) and NOAA Administrative Order (NAO) 216-6A, NMFS must review our proposed action ( i.e., the issuance of an IHA) with respect to potential impacts on the human environment. This action is consistent with categories of activities identified in Categorical Exclusion B4 (IHAs with no anticipated serious injury or mortality) of the Companion Manual for NOAA Administrative Order 216-6A, which do not individually or cumulatively have the potential for significant impacts on the quality of the human environment and for which we have not identified any extraordinary circumstances that would preclude this categorical exclusion. Accordingly, NMFS has preliminarily determined that the issuance of the proposed IHA qualifies to be categorically excluded from further NEPA review. We will review all comments submitted in response to this notice prior to concluding our NEPA process or making a final decision on the IHA request. Summary of Request On July 15, 2021 NMFS received a request from the Navy for an IHA to take marine mammals incidental to the reconstruction of Pier 3 at Naval Station Norfolk in Norfolk, Virginia. The application was deemed adequate and complete on October 27, 2021. Subsequently, the Navy provided a revised and updated version of the application, which was determined to be adequate and complete on January 10, 2022. The Navy's request is for take of a small number of five species by Level B harassment and Level A harassment. Neither the Navy nor NMFS expects serious injury or mortality to result from this activity and, therefore, an IHA is appropriate. NMFS previously issued IHAs to the Navy for similar work (86 FR 48986; September 1, 2021; 85 FR 33139; June 01, 2020; 83 FR 30406; June 28, 2018). This proposed IHA would cover one year of a larger project for which the Navy plans to submit a request for a Letter of Authorization (LOA) for additional work occurring from April 1, 2023 through December 30, 2026. The larger 4-year project involves the demolition and reconstruction of a submarine pier at Naval Station Norfolk. Description of Proposed Activity Overview The Navy is proposing the replacement of Pier 3 at Naval Station (NAVSTA) Norfolk in Norfolk, VA. The existing Pier 3 would be completely demolished and a new Pier 3 will be constructed immediately north of the existing location (See Figure 1). Work at Pier 4, Pier 3T and the bulkheads associated with Pier 3 and 3T (CEP-175, CEP-176, and CEP-102) will also occur (See Figure 1). The proposed project includes impact and vibratory pile driving and vibratory pile removal and drilling. Drilling is considered a continuous noise source, similar to vibratory pile driving. Sounds resulting from pile driving and removal may result in the incidental take of marine mammals by Level A and Level B harassment in the form of auditory injury or behavioral harassment. The in-water construction period for the proposed action will occur over 12 months. Dates and Duration The proposed IHA would be effective from April 1, 2022 to March 31, 2023. Approximately 280 days will be required for the project. The Navy plans to conduct all work during daylight hours. Specific Geographic Region Pier 3 at NAVSTA Norfolk is located at the confluence of the Elizabeth River, James River, Nansemond River, LaFeyette, Willoughby Bay, and Chesapeake Bay (Figure 2). Human generated sound is a significant contributor to the ambient acoustic environment surrounding NAVSTA Norfolk, as it is located in close proximity to shipping channels as well as several Port of Virginia facilities with frequent, noise-producing vessel traffic that, altogether, have an annual average of 1,788 vessel calls (Port of Virginia, 2021). Other sources of human-generated underwater sound not specific to naval installations include sounds from echo sounders on commercial and recreational vessels, industrial ship noise, and noise from recreational boat engines. Additionally, on average, maintenance dredging of the navigation channel occurs every 2 years (USACE and Port of Virginia, 2018). BILLING CODE 3510-22-P EN26JA22.002 EN26JA22.003 BILLING CODE 3510-22-C Detailed Description of Specific Activity The proposed project involves the replacement of Pier 3 at the NAVSTA waterfront. The existing Pier 3 would be completely demolished and a new Pier 3 would be constructed immediately north of the existing location. Additional work associated with the replacement of Pier 3 includes the outfitting of Pier 4 for temporary submarine berthing, demolition of Pier 3T, construction at the CEP-176 and the CEP-175 bulkheads, and beginning of construction of the CEP-102 bulkhead and relieving platform. The project includes six phases that will be completed under this proposed IHA and the future requested LOA. A preliminary work schedule and activity details for the work under this proposed IHA are provided in Table 1. In water construction activities and specific project phases that would occur under this IHA are described in more detail below: Pile Removal —Piles are anticipated to be removed with a vibratory hammer, however direct pull or clamshell removal may be used depending on site conditions. Since vibratory removal is the loudest activity, to be precautionary, we assume all piles will be removed with a vibratory hammer. Pile removal methods are described as follows: • Vibratory Extraction—This method uses a barge-mounted crane with a vibratory driver to remove all pile types. The vibratory driver is suspended from a crane by a cable and positioned on top of the pile to loosen the pile from the sediment. Once the pile is released from the sediments, the crane continues to raise the driver and pull the pile from the sediment and place it on a barge; • Clamshell—In cases where a vibratory driver is not possible ( e.g., when the pile may break apart from clamp force and vibration), a clamshell apparatus may be lowered from the crane in order to remove pile stubs. The use and size of the clamshell bucket would be minimized to reduce the potential for generating turbidity during removal; and • Direct Pull—Pile may also be removed by wrapping piles with a cable or chain and pulling them directly from the sediment with a crane. This method is based on site conditions. Pile Installation —The proposed pile installation/removal would occur using land-based or barge-mounted cranes and vary in method based on pile type. Concrete piles would be installed using an impact hammer. Steel piles and polymeric piles would be installed using an impact hammer or vibratory hammer. Drilling may also occur for the installation of concrete bearing piles at CEP-102, concrete fender piles, and polymeric fender piles. No concurrent activity will occur. Outfitting Pier 4 —In order to support the temporary berthing of submarines, Pier 4 fender support piles will be replaced with stronger, more structurally sound fender piles. On the south side of Pier 4 (see Figure 1), 36, 14-inch timber piles will be removed with a vibratory hammer and 36, 24-inch precast square concrete piles will be installed with an impact hammer with drilling used as necessary. Demolition of Pier 3T —The existing Pier 3T will be completely demolished and will not be replaced. Demolition of Pier 3T will include the removal of 286, 18-inch square concrete piles and 87, 14-inch timber piles using a vibratory hammer. CEP-175 Bulkhead —Once Pier 3T is demolished, a new fender system will be constructed at CEP-175 where Pier 3T previously abutted the bulkhead (see Figure 1). To accomplish this, nine, 13-inch polymeric fender piles would be installed to align with the existing fender system. Piles will be installed with either impact or vibratory hammers, with drilling used as necessary. Pier 3 Construction —The new Pier 3 will be constructed immediately north of and adjacent to the current Pier 3 (see Figure 1). The new pier will consist of a cast in place concrete deck supported by 530, 24-inch square concrete bearing piles. A fender system will be constructed on the north and south sides of the pier consisting of 392, 24-inch square concrete and 18, 18-inch steel pipe fender piles for berthing submarines. The fender system piles would not be installed in year one and therefore are not analyzed in this proposed IHA. CEP-176 Bulkhead —The wharf upgrade will consist of a new steel combi-wall bulkhead and relieving platform on the landside of the bulkhead that serves as the bulkhead anchoring system. The bulkhead will be constructed using 109, 42-inch steel pipe bearing piles and 221, 28-inch steel sheet piles. The steel pipe pile/steel sheet pile combination will be driven waterside of the existing deteriorated concrete bulkhead and will be installed with either an impact or vibratory hammer. Once Pier 3T is demolished and the new CEP-176 bulkheads are completed, dredging would occur along the face of CEP-176 bulkhead to allow for safe berthing and maneuvering. As described above, the project area is a noisy, industrial area. Noise created during dredging operations may exceed harassment thresholds, but is similar to noise produced through other common activities occurring at the project location and is unlikely to be distinguishable from the background noise created by ongoing industrial activity. Therefore, the likelihood of harassing marine mammals is reduced and no incidental takes are expected as a result of the dredging activity. Dredging and disposal activities are not discussed further in this document. CEP-102 Bulkhead —Repairs to the CEP-102 bulkhead will begin with the demolition of a portion of the existing fender pile system prior to new construction of Pier 3 and the CEP-176 bulkhead. Fender piles to be removed include: 22, 18-inch square concrete fender piles, 9, 14-inch timber fender piles, and 4, 13-inch polymeric piles. All piles will be removed by use of a vibratory hammer. A steel combi-wall bulkhead and a reinforced concrete relieving platform would then be constructed in two phases, with a small, approximately 50-foot portion, constructed concurrently with construction of the new Pier 3. Noise producing sources will not be used simultaneously, however. The portion of the CEP-102 combi-wall that will be constructed under this proposed IHA consists of 4, 42-inch steel pipe bearing piles and 8, 28-inch steel sheet piles that will be installed with either an impact or vibratory hammer. Eleven, 24-inch precast concrete fender piles will also be installed using an impact hammer. Drilling may be utilized as needed prior to the use of the impact hammer. Table 1 outlines a preliminary work schedule for the demolition and reconstruction of Pier 3 at NAVSTA. Some project elements will use only one method of pile installation ( e.g., vibratory OR drilling/impact OR impact only), but all methods have been analyzed. The method of installation will be determined by the construction crew once demolition and installation has begun. Therefore, the total take estimate reflects the worst case scenario for the proposed project. Table 1—Preliminary Estimated In-Water Construction Schedule for Year 1 Location Activity Amount and schedule Type and size Method 1 Daily production rate (piles/day) Strikes/duration per pile Total production days Pier 4 Demolition of Existing Fender Piles 36 fender piles June 2022-September 2022 14-inch timber Vibratory Hammer 4 60 minutes 9 Installation of Fender Piles 36 fender piles June 2022-September 2022 24-inch precast concrete square Drilling with Impact Hammer OR 6 6 hours 6 Impact Hammer 12 450 strikes 3 Pier 3T Demolition of Existing Pier 3T 286 bearing piles August 2022-November 2022 18-inch precast concrete square Vibratory Hammer 4 60 minutes 72 87 fender piles August 2022-November 2022 14-inch timber Vibratory Hammer 4 60 minutes 22 CEP-175 Repair Fender System 9 fender piles October 2022-November 2022 13-inch polymeric Drilling with Impact Hammer OR 7 60 minutes 2 Impact Hammer OR 7 450 strikes 2 Vibratory Hammer 7 30 minutes 2 CEP-102 Demolish Partial Existing Fender System 22 fender piles October 2022-November 2022 18-inch concrete square Vibratory Hammer 4 60 minutes 6 9 fender piles October 2022-November 2022 14-inch timber Vibratory Hammer 4 60 minutes 3 4 fender piles 13-inch polymeric Vibratory Hammer 4 60 minutes 1 Pier 3 Begin Construction of New Pier 3 300 bearing piles October 2022-March 2023 24-inch precast concrete square Impact Hammer 2 3,200 strikes 150 CEP-176 Begin Construction of New Bulkhead 109 bearing piles December 2022-30 March 2023 42-inch steel pipe Impact Hammer OR 2 1,800 strikes 55 Vibratory Hammer 2 240 minutes 55 221 sheet piles December 2022-30 March 2023 28-inch steel sheet Impact Hammer OR 4 270 strikes 56 Vibratory Hammer 4 60 minutes 56 CEP-102 Construction of a Portion of the New Bulkhead 4 bearing piles December 2022-30 March 2023 42-inch steep pipe Impact Hammer OR 2 2,000 strikes 2 Vibratory Hammer 2 240 minutes 2 8 bulkhead sheet piles December 2022-30 March 2023 28-inch steel sheet Impact Hammer OR 4 270 strikes 2 Vibratory Hammer 4 60 minutes 2 11 bearing piles December 2022-30 March 2023 24-inch precast concrete square Pre-drilling with Impact Hammer OR 2 6 hours 6 Impact Hammer 2 2,700 strikes 6 Total piles installed, extracted, or drilled 1,142 Total days pile driving/extraction/drilling 2 3 4 280 1 Only one method of installation is likely; however, because the exact means of installation are up to the selected construction contractor, all possibilities have been analyzed. 2 Total number of days takes into account the most days possible for each pile type with multiple potential installation methods ( i.e., the worst case scenario). 3 The preliminary schedule has work at Pier 4, demolition of Pier 3T, start of construction at Pier 3, and work at CEP-175 potentially occurring in the same timeframe, thus multiple pile types could be driven in the same day and the total days of pile driving/extraction/drilling reflects this assumption. Thus, the maximum number of days of work from these activities is associated with beginning the construction of Pier 3 (150 days). Adding remaining work, minus those activities that would occur during the same time frame (Pier 4, demo Pier 3T, and CEP-175), equals 280 days. 4 Multiple types of equipment may be used on the same day; however, use of multiple noise sources (hammers or drills) would not occur at the same time. There will be no simultaneous activities associated with this project. Proposed mitigation, monitoring, and reporting measures are described in detail later in this document (please see Proposed Mitigation and Proposed Monitoring and Reporting). Description of Marine Mammals in the Area of Specified Activities Sections 3 and 4 of the Navy's application summarize available information regarding status and trends, distribution and habitat preferences, and behavior and life history, of the potentially affected species. Additional information regarding population trends and threats may be found in NMFS's Stock Assessment Reports (SARs; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments ) and more general information about these species ( e.g., physical and behavioral descriptions) may be found on NMFS's website ( https://www.fisheries.noaa.gov/find-species ). Table 2 lists all species or stocks for which take is expected and proposed to be authorized for this action, and summarizes information related to the population or stock, including regulatory status under the MMPA and Endangered Species Act (ESA) and potential biological removal (PBR), where known. For taxonomy, we follow Committee on Taxonomy (2021). PBR is defined by the MMPA as the maximum number of animals, not including natural mortalities, that may be removed from a marine mammal stock while allowing that stock to reach or maintain its optimum sustainable population (as described in NMFS's SARs). While no mortality is anticipated or authorized here, PBR and annual serious injury and mortality from anthropogenic sources are included here as gross indicators of the status of the species and other threats. Marine mammal abundance estimates presented in this document represent the total number of individuals that make up a given stock or the total number estimated within a particular study or survey area. NMFS's stock abundance estimates for most species represent the total estimate of individuals within the geographic area, if known, that comprises that stock. For some species, this geographic area may extend beyond U.S. waters. All managed stocks in this region are assessed in NMFS's U.S. Atlantic and Gulf of Mexico SARs ( e.g., Hayes et al., 2021). All values presented in Table 2 are the most recent available at the time of publication and are available in the 2021 draft SARs (Hayes et al., 2021). Table 2—Marine Mammal Species Likely To Occur Near the Project Area Common name Scientific name Stock ESA/ MMPA status; strategic (Y/N) 1 Stock abundance (CV, N min , most recent abundance survey) 2 PBR Annual M/SI 3 Order Cetartiodactyla—Cetacea—Superfamily Mysticeti (baleen whales) Family Eschrichtiidae: Humpback whale Megaptera novaeangliae Gulf of Maine -,-;Y 1,396 (0; 1,380; 2016) 22 12.15 Superfamily Odontoceti (toothed whales, dolphins, and porpoises) Family Delphinidae: Bottlenose dolphin Tursiops truncatus Western North Atlantic (WNA) Coastal, Northern Migratory -,-; Y 6,636 (0.41; 4,759; 2016) 48 12.2-21.5 Bottlenose dolphin Tursiops truncatus WNA Coastal, Southern Migratory -,-; Y 3,751 (0.06; 2,353; 2016) 24 0-18.3 Bottlenose dolphin Tursiops truncatus Northern North Carolina Estuarine -,-; Y 823 (0.06; 782; 2017) 7.8 7.2-30 Family Phocoenidae (porpoises): Harbor porpoise Phocoena phocoena Gulf of Maine/Bay of Fundy -,-; N 95,543 (0.31; 74,034; 2016) 851 217 Order Carnivora—Superfamily Pinnipedia Family Phocidae (earless seals): Harbor seal Phoca vitulina WNA -; N 61,336 (0.08; 57,637; 2018) 1729 339 Gray seal 4 Halichoerus grypus WNA -; N 27,300 (0.22; 23,785; 2016) 1,389 4,453 1 Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed under the ESA is automatically designated under the MMPA as depleted and as a strategic stock. 2 NMFS marine mammal stock assessment reports online at: 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 [explain if this is the case]. 3 These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury (M/SI) from all sources combined ( e.g., commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV associated with estimated mortality due to commercial fisheries is presented in some cases. 4 This stock abundance estimate for only the U.S. portion of this stock. The actual stock abundance, including the Canadian portion of the population, is estimated to be approximately 451,431 animals. The PBR value listed here is only for the U.S. portion of the stock, while M/SI reflects both the Canadian and U.S. portions. As indicated above, all five species (with seven managed stocks) in Table 2 temporally and spatially co-occur with the activity to the degree that take is reasonably likely to occur, and we have proposed authorizing it. While North Atlantic right whales ( Eubalaena glacialis ), minke whales ( Balaenoptera acutorostrata acutorostrata ), and fin whales ( Balaenoptera physalus ) have been documented in the area, the temporal and/or spatial occurrence of these whales is far outside the proposed area for this project and take is not expected to occur. Therefore, they are not discussed further beyond the explanation provided below. Based on sighting data and passive acoustic studies, the North Atlantic right whale could occur off the coast of Virginia year-round (Department of Navy (DoN) 2009; Salisbury et al., 2006). They have also been reported seasonally off Virginia during migrations in the spring, fall, and winter (Cetacean and Turtle Assessment Program (CeTAP) 1981, 1982; Niemeyer et al., 2008; Kahn et al., 2009; McLellan 2011b, 2013; Mallette et al., 2016a, 2016b, 2017, 2018a; Palka et al., 2017; Cotter 2019). Right whales are known to frequent the coastal waters of the mouth of the Chesapeake Bay (Knowlton et al., 2002) and the area is a seasonal management area (November 1-April 30) mandating reduced ship speeds out to approximately 20 nautical miles (37 kilometers [km]); however, the project area is further inside the Bay and away from this area. North Atlantic right whales have stranded in Virginia, one each in 2001, 2002, 2004, 2005; three during winter (February and March) and one in summer (September) Costidis et al., 2017, 2019). In January 2018, a dead, entangled North Atlantic right whale was observed floating over 60 miles (96.6 km) offshore of Virginia Beach (Costidis et al., 2019). All North Atlantic right whale strandings in Virginia waters have occurred on ocean-facing beaches along Virginia Beach and the barrier islands seaward of the lower Delmarva Peninsula (Costidis et al., 2017). Right whales are not expected to occur in the project area, and NMFS is not proposing to authorize take of this species. Fin whales have been sighted off Virginia (CeTAP 1981, 1982; Swingle et al., 1993, DoN 2009; Hyrenback et al., 2012; Barco 2013; Mallette et al., 2016a, b; Aschettino et al., 2018; Engelhaupt et al., 2017, 2018; Cotter 2019), and in the Chesapeake Bay (Bailey 1948; CeTAP 1981, 1982; Morgan et al., 2002; Barco 2013; Aschettino et al., 2018); however, they are not likely to occur in the project area. Sightings have been documented around the Chesapeake Bay Bridge Tunnel (CBBT) during the winter months (CeTAP 1981, 1982; Barco 2013; Aschettino et al., 2018). Eleven fin whale strandings have occurred off Virginia from 1988 to 2016 mostly during the winter months of February and March, followed by a few in the spring and summer months (Costidis et al., 2017). Six of the strandings occurred in the Chesapeake Bay (three on eastern shore; three on western shore) with the remaining five occurring on the Atlantic coast (Costidis et al., 2017. Documented strandings near the project area have occurred: February 2012, a dead fin whale washed ashore on Oceanview Beach in Norfolk (Swingle et al., 2013); December 2017, a live fin whale stranded on a shoal in Newport News and died at the site (Swingle et al., 2018); February 2014, a dead fin whale stranded on a sand bar in Pocomoke Sound near Great Fox Island, Accomack (Swingle et al., 2015); and, March 2007, a dead fin whale near Craney Island, in the Elizabeth River, in Norfolk (Barco 2013). Only stranded fin whales have been documented in the project area; no free-swimming fin whales have been observed. Fin whales are not expected to occur in the project area, and NMFS is not proposing to authorize take of this species. Minke whales have been sighted off Virginia (CeTAP 1981, 1982; Hyrenbach et al., 2012; Barco 2013; Mallette et al., 2016a, b; McLellan 2017; Engelhaupt et al., 2017, 2018; Cotter 2019), near the CBBT (Aschettino et al., 2018), but sightings in the project area are from strandings (Jensen and Silber 2004; Barco 2013; DoN 2009). In August 1994, a ship strike incident involved a minke whale in Hampton Roads (Jensen and Silber 2004; Barco 2013). It was reported that the animal was struck offshore and was carried inshore on the bow of a ship (DoN 2009). Twelve strandings of minke whales have occurred in Virginia waters from 1988 to 2016 (Costidis et al., 2017). There have been six minke whale stranding from 2017 through 2020 in Virginia waters. Minke whales are not expected to occur in the project area, and NMFS is not proposing to authorize take of this species. Humpback Whales Humpback whales are found worldwide in all oceans. In winter, humpback whales from waters off New England, Canada, Greenland, Iceland, and Norway, migrate to mate and calve primarily in the West Indies, where spatial and genetic mixing among these groups occurs. NMFS defines a humpback whale stock on the basis of feeding location, i.e., Gulf of Maine. However, our reference to humpback whales in this document refers to any individual of the species that are found in the species geographic region. These individuals may be from the same breeding population ( e.g., West Indies breeding population of humpback whales) but visit different feeding areas. Based on photo-identification, only 39 percent of individual humpback whales observed along the mid- and south Atlantic U.S. coast are from the Gulf of Maine stock (Barco et al., 2002). Therefore, the SAR abundance estimate is an underrepresentation of the relevant population, i.e., the West Indies breeding population. Prior to 2016, humpback whales were listed under the ESA as an endangered species worldwide. Following a 2015 global status review (Bettridge et al., 2015), NMFS established 14 DPSs with different listing statuses (81 FR 62259; September 8, 2016) pursuant to the ESA. Humpback whales in the project area are expected to be from the West Indies DPS, which consists of the whales whose breeding range includes the Atlantic margin of the Antilles from Cuba to northern Venezuela, and whose feeding range primarily includes the Gulf of Maine, eastern Canada, and western Greenland. This DPS is not ESA listed. Bettridge et al., (2003) estimated the size of the West Indies DPS at 12,312 (95% CI 8,688-15,954) whales in 2004-05, which is consistent with previous population estimates of approximately 10,000-11,000 whales (Stevick et al., 2003; Smith et al., 1999) and the increasing trend for the West Indies DPS (Bettridge et al., 2015). Although humpback whales are migratory between feeding areas and calving areas, individual variability in the timing of migrations may result in the presence of individuals in high-latitude areas throughout the year (Straley, 1990). Records of humpback whales off the U.S. mid-Atlantic coast (New Jersey to North Carolina) from January through March suggest these waters may represent a supplemental winter feeding ground used by juvenile and mature humpback whales of U.S. and Canadian North Atlantic stocks (LaBrecque et al., 2015). Humpback whales are most likely to occur near the mouth of the Chesapeake Bay and coastal waters of Virginia Beach between January and March; however, they could be found in the area year-round, based on shipboard sighting and stranding data (Barco and Swingle, 2014; Aschettino et al., 2015; 2016; 2017; 2018). Photo-identification data support the repeated use of the mid-Atlantic region by individual humpback whales. Results of the vessel surveys show site fidelity in the survey area for some individuals and a high level of occurrence within shipping channels—an important high-use area by both the Navy and commercial traffic (Aschettino et al., 2015; 2016; 2017; 2018). Nearshore surveys conducted in early 2015 reported 61 individual humpback whale sightings, and 135 individual humpback whale sightings in late 2015 through May 2016 (Aschettino et al., 2016). Subsequent surveys confirmed the occurrence of humpback whales in the nearshore survey area: 248 individuals were detected in 2016-2017 surveys (Aschettino et al., 2017), 32 individuals were detected in 2017-2018 surveys (Aschettino et al., 2018), and 80 individuals were detected in 2019 surveys (Aschettino et al., 2019). Sightings in the Hampton Roads area in the vicinity of NAVSTA Norfolk were reported in nearshore surveys and through tracking of satellite-tagged whales in 2016, 2017 and 2019. The numbers of whales detected, most of which were juveniles, reflect the varying level of survey effort and changes in survey objectives from year to year, and do not indicate abundance trends over time. Most recently, the Hampton Roads Bridge-Tunnel Expansion Project (HRBT), which spanned from September 2020 through July 10, 2021 did not observe any humpback whales near the project site between Norfolk and Hampton, VA over 197 days of observations (Hampton Roads Connector Partners (HRCP), Unpublished ). Bottlenose Dolphin Along the U.S. East Coast and northern Gulf of Mexico, the bottlenose dolphin stock structure is well studied. There are currently 53 management stocks identified by NMFS in the western North Atlantic and Gulf of Mexico, including oceanic, coastal, and estuarine stocks (Hayes et al., 2017; Waring et al., 2015, 2016). There are two morphologically and genetically distinct bottlenose dolphin morphotypes (distinguished by physical differences) described as coastal and offshore forms (Duffield et al., 1983; Duffield, 1986). The offshore form is larger in total length and skull length, and has wider nasal bones than the coastal form. Both inhabit waters in the western North Atlantic Ocean and Gulf of Mexico (Curry and Smith, 1997; Hersh and Duffield, 1990; Mead and Potter, 1995) along the U.S. Atlantic coast. The coastal morphotype of bottlenose dolphin is continuously distributed along the Atlantic coast south of Long Island, New York, around the Florida peninsula, and along the Gulf of Mexico coast. This type typically occurs in waters less than 25 meters deep (Waring et al., 2015). The range of the offshore bottlenose dolphin includes waters beyond the continental slope (Kenney, 1990), and offshore bottlenose dolphins may move between the Gulf of Mexico and the Atlantic (Wells et al., 1999). Two coastal stocks are likely to be present in the project area: Western North Atlantic Northern Migratory Coastal stock and Western North Atlantic Southern Migratory Coastal stock. Additionally, the Northern North Carolina Estuarine System stock may occur in the project area. Bottlenose dolphins are the most abundant marine mammal along the Virginia coast and within the Chesapeake Bay, typically traveling in groups of 2 to 15 individuals, but occasionally in groups of over 100 individuals (Engelhaupt et al., 2014; 2015; 2016). Bottlenose dolphins of the Western North Atlantic Northern Migratory Coastal stock winter along the coast of North Carolina and migrate as far north as Long Island, New York, in the summer. They are rarely found north of North Carolina in the winter (NMFS, 2018a). The Western North Atlantic Southern Migratory Coastal stock occurs in waters of southern North Carolina from October to December, moving south during winter months and north to North Carolina during spring months. During July and August, the Western North Atlantic Southern Migratory Coastal stock is presumed to occupy coastal waters north of Cape Lookout, North Carolina, to the eastern shore of Virginia (NMFS, 2018a). It is possible that these animals also occur inside the Chesapeake Bay and in nearshore coastal waters. The North Carolina Estuarine System stock dolphins may also occur in the Chesapeake Bay during July and August (NMFS, 2018a). Vessel surveys conducted along coastal and offshore transects from NAVSTA Norfolk to Virginia Beach in most months from August 2012 to August 2015 reported bottlenose dolphins throughout the survey area, including the vicinity of NAVSTA Norfolk (Engelhaupt et al., 2014; 2015; 2016). The final results from this project confirmed earlier findings that bottlenose dolphins are common in the study area, with highest densities in the coastal waters in summer and fall months. However, bottlenose dolphins do not completely leave this area during colder months, with approximately 200-300 individuals still present in winter and spring months, which is commonly referred to as the Chesapeake Bay resident dolphin population (Engelhaupt et al., 2016). Harbor Porpoise Harbor porpoises inhabit cool temperate-to-subpolar waters, often where prey aggregations are concentrated (Watts and Gaskin, 1985). Thus, they are frequently found in shallow waters, most often near shore, but they sometimes move into deeper offshore waters. Harbor porpoises are rarely found in waters warmer than 63 degrees Fahrenheit (17 degrees Celsius) (Read 1999) and closely follow the movements of their primary prey, Atlantic herring (Gaskin 1992). In the western North Atlantic, harbor porpoise range from Cumberland Sound on the east coast of Baffin Island, southeast along the eastern coast of Labrador to Newfoundland and the Gulf of St. Lawrence, then southwest to about 34 degrees North on the coast of North Carolina (Waring et al., 2016). During winter (January to March), intermediate densities of harbor porpoises can be found in waters off New Jersey to North Carolina, and lower densities are found in waters off New York to New Brunswick, Canada (Waring et al., 2016). Harbor porpoises sighted off the mid-Atlantic during winter include porpoises from other western North Atlantic populations (Rosel et al., 1999). There does not appear to be a temporally coordinated migration or a specific migratory route to and from the Bay of Fundy region (Waring et al., 2016). During fall (October to December) and spring (April to June), harbor porpoises are widely dispersed from New Jersey to Maine, with lower densities farther north and south (LaBrecque et al., 2015). Based on stranding reports, passive acoustic recorders, and shipboard surveys, harbor porpoise occur in coastal waters primarily in winter and spring months, but there is little information on their presence in the Chesapeake Bay. They do not appear to be abundant in the NAVSTA Norfolk area in most years, but this is confounded by wide variations in stranding occurrences over the past decade. In the recent HRBT project, zero harbor porpoises were observed near the project area (HRCP, Unpublished ). Harbor Seal The Western North Atlantic stock of harbor seals occurs in the project area. Harbor seal distribution along the U.S. Atlantic coast has shifted in recent years, with an increased number of seals reported from southern New England to the mid-Atlantic region (DiGiovanni et al., 2011; Hayes et al., 2017; Kenney R.D. 2019; Waring et al., 2016). Regular sightings of seals in Virginia have become a common occurrence in winter and early spring (Costidis et al., 2019). Winter haulout sites for harbor seals have been documented in the Chesapeake Bay at the CBBT, on the Virginia Eastern Shore, and near Oregon Inlet, North Carolina (Waring et al., 2016; Rees et al., 2016; Jones et al., 2018). Harbor seals regularly haul out on rocks around the portal islands of the CBBT and on mud flats on the nearby southern tip of the Eastern Shore from December through April (Rees et al., 2016; Jones et al., 2018). Seals captured in 2018 on the Eastern Shore and tagged with satellite-tracked tags that lasted from 2 to 5 months spent at least 60 days in Virginia waters before departing the area. All tagged seals returned regularly to the capture site while in Virginia waters, but individuals utilized offshore and Chesapeake Bay waters to different extents (Ampela et al., 2019). The area that was utilized most heavily was near the Eastern Shore capture site, but some seals ranged into the Chesapeake Bay. To supplement this information, the HRBT project reported seeing zero seals in or around the project area (HRCP, Unpublished ). Gray Seal The Western North Atlantic stock of gray seal occurs in the project area. The western North Atlantic stock is centered in Canadian waters, including the Gulf of St. Lawrence and the Atlantic coasts of Nova Scotia, Newfoundland, and Labrador, Canada, and the northeast U.S. continental shelf (Hayes et al., 2017). Gray seals range south into the northeastern United States, with strandings and sightings as far south as North Carolina (Hammill et al., 1998; Waring et al., 2004). Gray seal distribution along the U.S. Atlantic coast has shifted in recent years, with an increased number of seals reported in southern New England (DiGiovanni et al., 2011; Kenney R.D., 2019; Waring et al., 2016). Recent sightings included a gray seal in the lower Chesapeake Bay during the winter of 2014 to 2015 (Rees et al., 2016). Along the coast of the United States, gray seals are known to pup at three or more colonies in Massachusetts and Maine. Gray seals are uncommon in Virginia and in the Chesapeake Bay. Only 15 gray seal strandings were documented in Virginia from 1988 through 2013 (Barco and Swingle, 2014). They are rarely found resting on the rocks around the portal islands of the CBBT from December through April alongside harbor seals. Seal observation surveys conducted at the CBBT recorded one gray seal in each of the 2014/2015 and 2015/2016 seasons while no gray seals were reported during the 2016/2017 and 2017/2018 seasons (Rees et al., 2016, Jones et al., 2018). Sightings have been reported off Virginia and near the project area during the winter and spring (Barco 2013; Rees et al., 2016; Jones et al., 2018; Ampela et al., 2019). However, the HRBT monitoring report indicated that zero gray seals were observed during the course of their project (HRCP, Unpublished ). Unusual Mortality Events An unusual mortality event (UME) is defined under Section 410(6) of the MMPA as a stranding that is unexpected; involves a significant die-off of any marine mammal population; and demands immediate response. Currently, ongoing UME investigations are underway for pinnipeds along the Northeast Atlantic coast. There is an active UME for humpback whales along the Atlantic coast. Northeast Pinniped UME Since July 2018, elevated numbers of harbor seal and gray seal mortalities have occurred across Maine, New Hampshire and Massachusetts. This event has been declared an UME. Additionally, seals showing clinical signs have been stranding as far south as Virginia, although not in elevated numbers; therefore, the UME investigation now encompasses all seal strandings from Maine to Virginia. Lastly, while take is not proposed for these species in this proposed IHA, ice seals (harp and hooded seals) have also started stranding with clinical signs, again not in elevated numbers, and those two seal species have also been added to the UME investigation. Additional information is available at https://www.fisheries.noaa.gov/new-england-mid-atlantic/marine-life-distress/2018-2020-pinniped-unusual-mortality-event-along. Atlantic Humpback Whale UME Since January 2016, elevated humpback whale mortalities have occurred along the Atlantic coast from Maine through Florida. This event has been declared an UME since 2017. A portion of the whales have shown evidence of pre-mortem vessel strike; however, this finding is not consistent across all whales examined, and additional research is needed. Additional information is available at https://www.fisheries.noaa.gov/national/marine-life-distress/2016-2021-humpback-whale-unusual-mortality-event-along-atlantic-coast. Marine Mammal Hearing Hearing is the most important sensory modality for marine mammals underwater, and exposure to anthropogenic sound can have deleterious effects. To appropriately assess the potential effects of exposure to sound, it is necessary to understand the frequency ranges marine mammals are able to hear. Current data indicate that not all marine mammal species have equal hearing capabilities ( e.g., Richardson et al., 1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al., (2007) recommended that marine mammals be divided into functional hearing groups based on directly measured or estimated hearing ranges on the basis of available behavioral response data, audiograms derived using auditory evoked potential techniques, anatomical modeling, and other data. Note that no direct measurements of hearing ability have been successfully completed for mysticetes ( i.e., low-frequency cetaceans). Subsequently, NMFS (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 and Holt, 2013). For more detail concerning these groups and associated frequency ranges, please see NMFS (2018) for a review of available information. Five marine mammal species (three cetacean and two pinniped, both phocid, species) have the reasonable potential to co-occur with the proposed survey activities. Please refer to Table 2. Of the cetacean species that may be present, one is classified as a low-frequency cetacean ( i.e., humpback whale), one is classified as a mid-frequency cetacean ( i.e., bottlenose dolphin), and one is classified as a high-frequency cetacean ( i.e., harbor porpoise). Potential Effects of Specified Activities on Marine Mammals and Their Habitat This section includes a summary and discussion of the ways that components of the specified activity may impact marine mammals and their habitat. The Estimated Take section later in this document includes a quantitative analysis of the number of individuals that are expected to be taken by this activity. The Negligible Impact Analysis and Determination section considers the content of this section, the Estimated Take section, and the Proposed Mitigation section, to draw conclusions regarding the likely impacts of these activities on the reproductive success or survivorship of individuals and how those impacts on individuals are likely to impact marine mammal species or stocks. Description of Sound Sources The marine soundscape is comprised of both ambient and anthropogenic sounds. Ambient sound is defined as the all-encompassing sound in a given place and is usually a composite of sound from many sources both near and far. The sound level of an area is defined by the total acoustical energy being generated by known and unknown sources. These sources may include physical ( e.g., waves, wind, precipitation, earthquakes, ice, atmospheric sound), biological ( e.g., sounds produced by marine mammals, fish, and invertebrates), and anthropogenic sound ( e.g., vessels, dredging, aircraft, construction). The sum of the various natural and anthropogenic sound sources at any given location and time—which comprise “ambient” or “background” sound—depends not only on the source levels (as determined by current weather conditions and levels of biological and shipping activity) but also on the ability of sound to propagate through the environment. In turn, sound propagation is dependent on the spatially and temporally varying properties of the water column and sea floor, and is frequency-dependent. As a result of the dependence on a large number of varying factors, ambient sound levels can be expected to vary widely over both coarse and fine spatial and temporal scales. Sound levels at a given frequency and location can vary by 10-20 dB from day to day (Richardson et al., 1995). The result is that, depending on the source type and its intensity, sound from the specified activity may be a negligible addition to the local environment or could form a distinctive signal that may affect marine mammals. In-water construction activities associated with the project would include vibratory pile removal, impact and vibratory pile driving, and drilling. The sounds produced by these activities fall into one of two general sound types: Impulsive and non-impulsive. Impulsive sounds ( e.g., explosions, gunshots, sonic booms, impact pile driving) are typically transient, brief (less than 1 second), broadband, and consist of high peak sound pressure with rapid rise time and rapid decay (ANSI 1986; NIOSH 1998; ANSI 2005; NMFS 2018a). Non-impulsive sounds ( e.g. aircraft, machinery operations such as drilling or dredging, vibratory pile driving, and active sonar systems) can be broadband, narrowband or tonal, brief or prolonged (continuous or intermittent), and typically do not have the high peak sound pressure with raid rise/decay time that impulsive sounds do (ANSI 1995; NIOSH 1998; NMFS 2018a). The distinction between these two sound types is important because they have differing potential to cause physical effects, particularly with regard to hearing ( e.g., Ward 1997 in Southall et al., 2007). Impact hammers operate by repeatedly dropping a heavy piston onto a pile to drive the pile into the substrate. Sound generated by impact hammers is characterized by rapid rise times and high peak levels, a potentially injurious combination (Hastings and Popper 2005). Vibratory hammers install piles by vibrating them and allowing the weight of the hammer to push them into the sediment. The vibrations produced also cause liquefaction of the substrate surrounding the pile, enabling the pile to be extracted or driven into the ground more easily. Vibratory hammers produce significantly less sound than impact hammers. Peak sound pressure levels (SPLs) may be 180 dB or greater, but are generally 10 to 20 dB lower than SPLs generated during impact pile driving of the same-sized pile (Oestman et al., 2009). Rise time is slower, reducing the probability and severity of injury, and sound energy is distributed over a greater amount of time (Nedwell and Edwards 2002; Carlson et al., 2005). As mentioned previously, drilling is considered a continuous source, similar to vibratory pile driving. The drilling may be used before driving piles in order to facilitate pile driving and hence the applicant calls this activity “pre-drilling” in their application. For the proposed project, the drilling apparatus utilized would vary depending on the different applications during in-water construction activities. Drilling would be used as necessary to remove sand with shell fragments or any obstructions in order to accelerate pile driving. The likely or possible impacts of the Navy's proposed activity on marine mammals could involve both non-acoustic and acoustic stressors. Potential non-acoustic stressors could result from the physical presence of the equipment and personnel; however, any impacts to marine mammals are expected to be primarily acoustic in nature. Acoustic stressors include effects of heavy equipment operation during pile driving, removal and drilling. Acoustic Impacts The introduction of anthropogenic noise into the aquatic environment from pile driving or drilling is the primary means by which marine mammals may be harassed from the Navy's specified activity. In general, animals exposed to natural or anthropogenic sound may experience physical and psychological effects, ranging in magnitude from none to severe (Southall et al., 2007). In general, exposure to pile driving or drilling noise has the potential to result in auditory threshold shifts and behavioral reactions ( e.g., avoidance, temporary cessation of foraging and vocalizing, changes in dive behavior). Exposure to anthropogenic noise can also lead to non-observable physiological responses such an increase in stress hormones. Additional noise in a marine mammal's habitat can mask acoustic cues used by marine mammals to carry out daily functions such as communication and predator and prey detection. The effects of pile driving or drilling noise on marine mammals are dependent on several factors, including, but not limited to, sound type ( e.g., impulsive vs. non-impulsive), the species, age and sex class ( e.g., adult male vs. mom with calf), duration of exposure, the distance between the pile and the animal, received levels, behavior at time of exposure, and previous history with exposure (Wartzok et al., 2004; Southall et al., 2007). Here we discuss physical auditory effects (threshold shifts) followed by behavioral effects and potential impacts on habitat. NMFS defines a noise-induced threshold shift (TS) as a change, usually an increase, in the threshold of audibility at a specified frequency or portion of an individual's hearing range above a previously established reference level (NMFS 2018). The amount of threshold shift is customarily expressed in decibels (dB). A TS can be permanent or temporary. As described in NMFS (2018), there are numerous factors to consider when examining the consequence of TS, including, but not limited to, the signal temporal pattern ( e.g., impulsive or non-impulsive), likelihood an individual would be exposed for a long enough duration or to a high enough level to induce a TS, the magnitude of the TS, time to recovery (seconds to minutes or hours to days), the frequency range of the exposure ( i.e., spectral content), the hearing and vocalization frequency range of the exposed species relative to the signal's frequency spectrum ( i.e., how an animal uses sound within the frequency band of the signal; e.g., Kastelein et al., 2014), and the overlap between the animal and the source ( e.g., spatial, temporal, and spectral). Permanent Threshold Shift (PTS) —NMFS defines PTS as a permanent, irreversible increase in the threshold of audibility at a specified frequency or portion of an individual's hearing range above a previously established reference level (NMFS 2018). Available data from humans and other terrestrial mammals indicate that a 40 dB threshold shift approximates PTS onset (see Ward et al., 1958, 1959; Ward 1960; Kryter et al., 1966; Miller 1974; Ahroon et al., 1996; Henderson et al., 2008). PTS levels for marine mammals are estimates, as with the exception of a single study unintentionally inducing PTS in a harbor seal (Kastak et al., 2008), there are no empirical data measuring PTS in marine mammals largely due to the fact that, for various ethical reasons, experiments involving anthropogenic noise exposure at levels inducing PTS are not typically pursued or authorized (NMFS 2018). Temporary Threshold Shift (TTS) —TTS is a temporary, reversible increase in the threshold of audibility at a specified frequency or portion of an individual's hearing range above a previously established reference level (NMFS 2018). Based on data from cetacean TTS measurements (see Southall et al., 2007), a TTS of 6 dB is considered the minimum threshold shift clearly larger than any day-to-day or session-to-session variation in a subject's normal hearing ability (Schlundt et al., 2000; Finneran et al., 2000, 2002). As described in Finneran (2015), marine mammal studies have shown the amount of TTS increases with cumulative sound exposure level (SELcum) in an accelerating fashion: At low exposures with lower SELcum, the amount of TTS is typically small and the growth curves have shallow slopes. At exposures with higher SELcum, the growth curves become steeper and approach linear relationships with the noise SEL. Depending on the degree (elevation of threshold in dB), duration ( i.e., recovery time), and frequency range of TTS, and the context in which it is experienced, TTS can have effects on marine mammals ranging from discountable to serious (similar to those discussed in auditory masking, below). For example, a marine mammal may be able to readily compensate for a brief, relatively small amount of TTS in a non-critical frequency range that takes place during a time when the animal is traveling through the open ocean, where ambient noise is lower and there are not as many competing sounds present. Alternatively, a larger amount and longer duration of TTS sustained during a time when communication is critical for successful mother/calf interactions could have more serious impacts. We note that reduced hearing sensitivity as a simple function of aging has been observed in marine mammals, as well as humans and other taxa (Southall et al., 2007), so we can infer that strategies exist for coping with this condition to some degree, though likely not without cost. Currently, TTS data only exist for four species of cetaceans (bottlenose dolphin, beluga whale ( Delphinapterus leucas ), harbor porpoise, and Yangtze finless porpoise ( Neophocoena asiaeorientalis )) and five species of pinnipeds exposed to a limited number of sound sources ( i.e., mostly tones and octave-band noise) in laboratory settings (Finneran 2015). TTS was not observed in trained spotted ( Phoca largha ) and ringed ( Pusa hispida ) seals exposed to impulsive noise at levels matching previous predictions of TTS onset (Reichmuth et al., 2016). In general, harbor seals and harbor porpoises have a lower TTS onset than other measured pinniped or cetacean species (Finneran 2015). Additionally, the existing marine mammal TTS data come from a limited number of individuals within these species. No data are available on noise-induced hearing loss for mysticetes. For summaries of data on TTS in marine mammals or for further discussion of TTS onset thresholds, please see Southall et al., (2007), Finneran and Jenkins (2012), Finneran (2015), and Table 5 in NMFS (2018). Installing piles for this project requires a combination of drilling, impact pile driving and vibratory pile driving. For this project, these activities would not occur at the same time and there would be pauses in activities producing the sound during each day. Given these pauses and that many marine mammals are likely moving through the ensonified area and not remaining for extended periods of time, the potential for TS declines. Behavioral Harassment —Exposure to noise from pile driving and removal also has the potential to behaviorally disturb marine mammals. Available studies show wide variation in response to underwater sound; therefore, it is difficult to predict specifically how any given sound in a particular instance might affect marine mammals perceiving the signal. If a marine mammal does react briefly to an underwater sound by changing its behavior or moving a small distance, the impacts of the change are unlikely to be significant to the individual, let alone the stock or population. However, if a sound source displaces marine mammals from an important feeding or breeding area for a prolonged period, impacts on individuals and populations could be significant ( e.g., Lusseau and Bejder 2007; Weilgart 2007; NRC 2005). Disturbance may result in changing durations of surfacing and dives, number of blows per surfacing, or moving direction and/or speed; reduced/increased vocal activities; changing/cessation of certain behavioral activities (such as socializing or feeding); visible startle response or aggressive behavior (such as tail/fluke slapping or jaw clapping); avoidance of areas where sound sources are located. Pinnipeds may increase their haul out time, possibly to avoid in-water disturbance (Thorson and Reyff 2006). Behavioral responses to sound are highly variable and context-specific and any reactions depend on numerous intrinsic and extrinsic factors ( e.g., species, state of maturity, experience, current activity, reproductive state, auditory sensitivity, time of day), as well as the interplay between factors ( e.g., Richardson et al., 1995; Wartzok et al., 2003; Southall et al., 2007; Weilgart 2007; Archer et al., 2010). Behavioral reactions can vary not only among individuals but also within an individual, depending on previous experience with a sound source, context, and numerous other factors (Ellison et al., 2012), and can vary depending on characteristics associated with the sound source ( e.g., whether it is moving or stationary, number of sources, distance from the source). In general, pinnipeds seem more tolerant of, or at least habituate more quickly to, potentially disturbing underwater sound than do cetaceans, and generally seem to be less responsive to exposure to industrial sound than most cetaceans. Please see Appendices B-C of Southall et al., (2007) for a review of studies involving marine mammal behavioral responses to sound. Disruption of feeding behavior can be difficult to correlate with anthropogenic sound exposure, so it is usually inferred by observed displacement from known foraging areas, the appearance of secondary indicators ( e.g., bubble nets or sediment plumes), or changes in dive behavior. As for other types of behavioral response, the frequency, duration, and temporal pattern of signal presentation, as well as differences in species sensitivity, are likely contributing factors to differences in response in any given circumstance ( e.g., Croll et al., 2001; Nowacek et al., 2004; Madsen et al., 2006; Yazvenko et al., 2007). A determination of whether foraging disruptions incur fitness consequences would require information on or estimates of the energetic requirements of the affected individuals and the relationship between prey availability, foraging effort and success, and the life history stage of the animal. Stress responses —An animal's perception of a threat may be sufficient to trigger stress responses consisting of some combination of behavioral responses, autonomic nervous system responses, neuroendocrine responses, or immune responses ( e.g., Seyle 1950; Moberg 2000). In many cases, an animal's first and sometimes most economical (in terms of energetic costs) response is behavioral avoidance of the potential stressor. Autonomic nervous system responses to stress typically involve changes in heart rate, blood pressure, and gastrointestinal activity. These responses have a relatively short duration and may or may not have a significant long-term effect on an animal's fitness. Neuroendocrine stress responses often involve the hypothalamus-pituitary-adrenal system. Virtually all neuroendocrine functions that are affected by stress—including immune competence, reproduction, metabolism, and behavior—are regulated by pituitary hormones. Stress-induced changes in the secretion of pituitary hormones have been implicated in failed reproduction, altered metabolism, reduced immune competence, and behavioral disturbance ( e.g., Moberg 1987; Blecha 2000). Increases in the circulation of glucocorticoids are also equated with stress (Romano et al., 2004). The primary distinction between stress (which is adaptive and does not normally place an animal at risk) and “distress” is the cost of the response. During a stress response, an animal uses glycogen stores that can be quickly replenished once the stress is alleviated. In such circumstances, the cost of the stress response would not pose serious fitness consequences. However, when an animal does not have sufficient energy reserves to satisfy the energetic costs of a stress response, energy resources must be diverted from other functions. This state of distress will last until the animal replenishes its energetic reserves sufficient to restore normal function. Relationships between these physiological mechanisms, animal behavior, and the costs of stress responses are well studied through controlled experiments and for both laboratory and free-ranging animals ( e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003; Krausman et al., 2004; Lankford et al., 2005). Stress responses due to exposure to anthropogenic sounds or other stressors and their effects on marine mammals have also been reviewed (Fair and Becker 2000; Romano et al., 2002b) and, more rarely, studied in wild populations ( e.g., Romano et al., 2002a). For example, Rolland et al., (2012) found that noise reduction from reduced ship traffic in the Bay of Fundy was associated with decreased stress in North Atlantic right whales. These and other studies lead to a reasonable expectation that some marine mammals will experience physiological stress responses upon exposure to acoustic stressors and that it is possible that some of these would be classified as “distress.” In addition, any animal experiencing TTS would likely also experience stress responses (NRC, 2003), however distress is an unlikely result of this project based on observations of marine mammals during previous, similar projects in the area. Masking —Sound can disrupt behavior through masking, or interfering with, an animal's ability to detect, recognize, or discriminate between acoustic signals of interest ( e.g., those used for intraspecific communication and social interactions, prey detection, predator avoidance, navigation) (Richardson et al., 1995). Masking occurs when the receipt of a sound is interfered with by another coincident sound at similar frequencies and at similar or higher intensity, and may occur whether the sound is natural ( e.g., snapping shrimp, wind, waves, precipitation) or anthropogenic ( e.g., pile driving, shipping, sonar, seismic exploration) in origin. The ability of a noise source to mask biologically important sounds depends on the characteristics of both the noise source and the signal of interest ( e.g., signal-to-noise ratio, temporal variability, direction), in relation to each other and to an animal's hearing abilities ( e.g., sensitivity, frequency range, critical ratios, frequency discrimination, directional discrimination, age or TTS hearing loss), and existing ambient noise and propagation conditions. Masking of natural sounds can result when human activities produce high levels of background sound at frequencies important to marine mammals. Conversely, if the background level of underwater sound is high ( e.g., on a day with strong wind and high waves), an anthropogenic sound source would not be detectable as far away as would be possible under quieter conditions and would itself be masked. Airborne Acoustic Effects —Although pinnipeds are known to haul-out regularly on man-made objects, such as the nearby Chesapeake Bay Bridge Tunnel, we believe that incidents of take resulting solely from airborne sound are unlikely due to the sheltered proximity between the proposed project area and these haulout sites (over 16 miles (26 km)). There is a possibility that an animal could surface in-water, but with head out, within the area in which airborne sound exceeds relevant thresholds and thereby be exposed to levels of airborne sound that we associate with harassment, but any such occurrence would likely be accounted for in our estimation of incidental take from underwater sound. Therefore, authorization of incidental take resulting from airborne sound for pinnipeds is not warranted, and airborne sound is not discussed further here. Cetaceans are not expected to be exposed to airborne sounds that would result in harassment as defined under the MMPA. Marine Mammal Habitat Effects The Navy's construction activities could have localized, temporary impacts on marine mammal habitat by increasing in-water sound pressure levels and slightly decreasing water quality. However, since the focus of the proposed action is pile driving and drilling, no net habitat loss is expected as the new Pier 3 will be immediately north of the existing Pier 3 and once complete, the current Pier 3 will be demolished. Construction activities are of short duration and would likely have temporary impacts on marine mammal habitat through increases in underwater sounds. Increased noise levels may affect acoustic habitat (see masking discussion above) and adversely affect marine mammal prey in the vicinity of the project area (see discussion below). During pile driving activities, elevated levels of underwater noise would ensonify the project area where both fishes and marine mammals may occur and could affect foraging success. Additionally, marine mammals may avoid the area during construction, however displacement due to noise is expected to be temporary and is not expected to result in long-term effects to the individuals or populations. Temporary and localized reduction in water quality will occur because of in-water construction activities as well. Most of this effect will occur during the installation and removal of piles when bottom sediments are disturbed. The installation of piles will disturb bottom sediments and may cause a temporary increase in suspended sediment in the project area. In general, turbidity associated with pile installation is localized to about 25-ft (7.6 meter) radius around the pile (Everitt et al., 1980). Cetaceans are not expected to be close enough to the pile driving areas to experience effects of turbidity, and any pinnipeds could avoid localized areas of turbidity. Therefore, we expect the impact from increased turbidity levels to be discountable to marine mammals and do not discuss it further. In-Water Construction Effects on Potential Foraging Habitat The proposed activities would not result in permanent impacts to habitats used directly by marine mammals except for the actual footprint of the new Pier 3. The total seafloor area affected by pile installation and removal is a very small area compared to the vast foraging area available to marine mammals in the project area and lower Chesapeake Bay. Pile extraction and installation may have impacts on benthic invertebrate species primarily associated with disturbance of sediments that may cover or displace some invertebrates. The impacts will be temporary and highly localized, and no habitat will be permanently displaced by construction. Therefore, it is expected that impacts on foraging opportunities for marine mammals due to the demolition and reconstruction of Pier 3 would be minimal. It is possible that avoidance by potential prey ( i.e., fish) in the immediate area may occur due to temporary loss of this foraging habitat. The duration of fish avoidance of this area after pile driving stops is unknown, but we anticipate a rapid return to normal recruitment, distribution and behavior. Any behavioral avoidance by fish of the disturbed area would still leave large areas of fish and marine mammal foraging habitat in the nearby vicinity in the in the project area and lower Chesapeake Bay. Effects on Potential Prey Sound may affect marine mammals through impacts on the abundance, behavior, or distribution of prey species ( e.g., fish). Marine mammal prey varies by species, season, and location. Here, we describe studies regarding the effects of noise on known marine mammal prey. Fish utilize the soundscape and components of sound in their environment to perform important functions such as foraging, predator avoidance, mating, and spawning ( e.g., Zelick et al., 1999; Fay, 2009). Depending on their hearing anatomy and peripheral sensory structures, which vary among species, fishes hear sounds using pressure and particle motion sensitivity capabilities and detect the motion of surrounding water (Fay et al., 2008). The potential effects of noise on fishes depends on the overlapping frequency range, distance from the sound source, water depth of exposure, and species-specific hearing sensitivity, anatomy, and physiology. Key impacts to fishes may include behavioral responses, hearing damage, barotrauma (pressure-related injuries), and mortality. Fish react to sounds which are especially strong and/or intermittent low-frequency sounds, and behavioral responses such as flight or avoidance are the most likely effects. Short duration, sharp sounds can cause overt or subtle changes in fish behavior and local distribution. The reaction of fish to noise depends on the physiological state of the fish, past exposures, motivation ( e.g., feeding, spawning, migration), and other environmental factors. Hastings and Popper (2005) identified several studies that suggest fish may relocate to avoid certain areas of sound energy. Additional studies have documented effects of pile driving on fish, although several are based on studies in support of large, multiyear bridge construction projects ( e.g., Scholik and Yan, 2001, 2002; Popper and Hastings, 2009). Several studies have demonstrated that impulse sounds might affect the distribution and behavior of some fishes, potentially impacting foraging opportunities or increasing energetic costs ( e.g., Fewtrell and McCauley, 2012; Pearson et al., 1992; Skalski et al., 1992; Santulli et al., 1999; Paxton et al., 2017). However, some studies have shown no or slight reaction to impulse sounds ( e.g., Pena et al., 2013; Wardle et al., 2001; Jorgenson and Gyselman, 2009; Cott et al., 2012). SPLs of sufficient strength have been known to cause injury to fish and fish mortality. However, in most fish species, hair cells in the ear continuously regenerate and loss of auditory function likely is restored when damaged cells are replaced with new cells. Halvorsen et al., (2012a) showed that a TTS of 4-6 dB was recoverable within 24 hours for one species. Impacts would be most severe when the individual fish is close to the source and when the duration of exposure is long. Injury caused by barotrauma can range from slight to severe and can cause death, and is most likely for fish with swim bladders. Barotrauma injuries have been documented during controlled exposure to impact pile driving (Halvorsen et al., 2012b; Casper et al., 2013). The most likely impact to fish from pile driving activities at the project areas would be temporary behavioral avoidance of the area. The duration of fish avoidance of an area after pile driving stops is unknown, but a rapid return to normal recruitment, distribution and behavior is anticipated. The area impacted by the project is relatively small compared to the available habitat in the remainder of the project area and the lower Chesapeake Bay, and there are no areas of particular importance that would be impacted by this project. Any behavioral avoidance by fish of the disturbed area would still leave significantly large areas of fish and marine mammal foraging habitat in the nearby vicinity. As described in the preceding, the potential for the Navy's construction to affect the availability of prey to marine mammals or to meaningfully impact the quality of physical or acoustic habitat is considered to be insignificant. Estimated Take This section provides an estimate of the number of incidental takes proposed for authorization through this IHA, which will inform both NMFS' consideration of “small numbers” and the negligible impact determination. Harassment is the only type of take expected to result from these activities. Except with respect to certain activities not pertinent here, section 3(18) of the MMPA defines “harassment” as any act of pursuit, torment, or annoyance, which (i) has the potential to injure a marine mammal or marine mammal stock in the wild (Level A harassment); or (ii) has the potential to disturb a marine mammal or marine mammal stock in the wild by causing disruption of behavioral patterns, including, but not limited to, migration, breathing, nursing, breeding, feeding, or sheltering (Level B harassment). Authorized takes would primarily be by Level B harassment, as noise generated from in-water pile driving (vibratory and impact) and drilling has the potential to result in disruption of behavioral patterns for individual marine mammals. There is also some potential for auditory injury (Level A harassment) to result, primarily for high- and low-frequency species and phocids because predicted auditory injury zones are larger than for mid-frequency species. However, auditory injury is unlikely to occur for mid-frequency species due to the proposed shutdown zones (see Proposed Mitigation section). Additionally, the proposed mitigation and monitoring measures are expected to minimize the severity of the taking to the extent practicable. As described previously, no mortality is anticipated or proposed to be authorized for this activity. Below we describe how the take is estimated. 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) and the number of days of activities. We note that while these basic factors can contribute to a basic calculation to provide an initial prediction of 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 proposed take estimate. Acoustic Thresholds NMFS recommends the use of acoustic thresholds that identify the received level of underwater sound above which exposed marine mammals would be reasonably expected to be behaviorally harassed (equated to Level B harassment) or to incur PTS of some degree (equated to Level A harassment). Level B Harassment for non-explosive sources —Though significantly driven by received level, the onset of behavioral disturbance from anthropogenic noise exposure is also informed to varying degrees by other factors related to the source ( e.g., frequency, predictability, duty cycle), the environment ( e.g., bathymetry), and the receiving animals (hearing, motivation, experience, demography, behavioral context) and can be difficult to predict (Southall et al., 2007, Ellison et al., 2012). Based on what the available science indicates and the practical need to use a threshold based on a factor that is both predictable and measurable for most activities, NMFS uses a generalized acoustic threshold based on received level to estimate the onset of behavioral harassment. NMFS predicts that marine mammals are likely to be behaviorally harassed in a manner we consider Level B harassment when exposed to underwater anthropogenic noise above received levels of 120 dB re 1 microPascal, root mean square (μPa (rms)) for continuous ( e.g., vibratory pile-driving, drilling) and above 160 dB re 1 μPa (rms) for non-explosive impulsive ( e.g., impact pile driving) or intermittent ( e.g., scientific sonar) sources. The Navy's construction includes the use of continuous (vibratory pile driving, drilling) and impulsive (impact pile driving) sources, and therefore the 120 and 160 dB re 1 μPa (rms) are applicable. Level A harassment for non-explosive sources —NMFS' Technical Guidance for Assessing the Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 2.0) (Technical Guidance, 2018) identifies dual criteria to assess auditory injury (Level A harassment) to five different marine mammal groups (based on hearing sensitivity) as a result of exposure to noise from two different types of sources (impulsive or non-impulsive). As previously noted, the Navy's proposed activity include the use of impulsive (impact pile driving) and non-impulsive (vibratory pile driving/removal, drilling) sources. These thresholds are provided in the table below. The references, analysis, and methodology used in the development of the thresholds are described in NMFS 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: L pk,flat : 219 dB; L E,LF,24h : 183 dB Cell 2: L E,LF,24h : 199 dB. Mid-Frequency (MF) Cetaceans Cell 3: L pk,flat : 230 dB; L E,MF,24h : 185 dB Cell 4: L E,MF,24h : 198 dB. High-Frequency (HF) Cetaceans Cell 5: L pk,flat : 202 dB; L E,HF,24h : 155 dB Cell 6: L E,HF,24h : 173 dB. Phocid Pinnipeds (PW) (Underwater) Cell 7: L pk,flat : 218 dB; L E,PW,24h : 185 dB Cell 8: L E,PW,24h : 201 dB. Otariid Pinnipeds (OW) (Underwater) Cell 9: L pk,flat : 232 dB; L E,OW,24h : 203 dB Cell 10: L E,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 ( L pk ) has a reference value of 1 µPa, and cumulative sound exposure level ( L E ) has a reference value of 1µPa 2 s. In this Table, thresholds are abbreviated to reflect American National Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI as incorporating frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript “flat” is being included to indicate peak sound pressure should be flat weighted or unweighted within the generalized hearing range. The subscript associated with cumulative sound exposure level thresholds indicates the designated marine mammal auditory 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 will feed into identifying the area ensonified above the acoustic thresholds, which include source levels and transmission loss coefficient. In order to calculate the distances to the Level A harassment and the Level B harassment sound thresholds for the methods 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 (Table 5). Generally we choose source levels from similar pile types from locations ( e.g., geology, bathymetry) similar to the project. At this time, NMFS is not aware of reliable source levels available for polymeric piles using vibratory pile installation, therefore source levels for timber pile driving were used as a proxy. Similarly, the following proxies were used as source levels for piles where no data was available: Source levels for the 66-inch steel pile was used as a proxy for 42-inch steel pipe piles (vibratory); the 30-inch steel pile was used as a proxy for the 28-inch sheet piles (impact); and 18-inch octagonal pile was used as a proxy for 18-inch concrete piles (impact). Additionally, data on vibratory extraction of concrete piles are not available, therefore the Navy followed previous guidance suggesting that timber piles be used as a proxy for sound source levels (see 84 FR 28474; June 19, 2019). Very little information is available regarding source levels for in-water drilling activities associated with nearshore pile installation. Measurements made during a pile drilling project in 1-5 m (3-16 ft) depths at Santa Rosa Island, CA, by Dazey et al., (2012) appear to provide the best available proxy source levels for the proposed activities. Dazey et al. (2012) reported average rms source levels ranging from 151 to 157 dB re 1µPa, normalized to a distance of 1 m (3 ft) from the pile, during activities that included casing removal and installation as well as drilling, with an average of 154 dB re 1µPa during 62 days that spanned all related drilling activities during a single season. The sound field in the project area is the existing background noise plus additional construction noise from the proposed project. Marine mammals are expected to be affected via sound generated by the primary components of the project ( i.e., impact pile driving, vibratory pile driving, and drilling). Table 5—Project Sound Source Levels Normalized to 10 Meters Pile type Pile size (inch) Method Peak SPL (re 1 μPa (rms)) RMS SPL (re 1 μPa (rms)) SEL (re 1 μPa (rms)) Source Steel Pipe Pile 42 Impact Vibratory 213 168 190 168 177 168 Navy 2015. Sitka 2017. Steel Sheet 28 Impact Vibratory 211 196 167 181 167 NAVFAC SW 2020. Navy 2015. Concrete Pile 24 Impact Vibratory 189 185 176 162 163 157 Illingworth and Rodkin 2017. Caltrans 2020. Concrete Pile 18 Impact Vibratory 185 185 166 162 154 157 Caltrans 2020. Caltrans 2020. Polymeric Pile 13 Impact Vibratory 177 185 153 162 157 Denes et al., 2016. Caltrans 2020. Timber Pile 14 Vibratory 185 162 157 Caltrans 2020. NA “Multiple pile sizes” 1 2 Drilling 2 154 154 Dazey et al., 2012. 1 Pile sizes being installed using the drilling method might include 24-inch precast concrete square, 13-inch polymeric and 24-inch precast concrete square. 2 Source levels were normalized to a distance of 1 m (3 ft) from the pile during activities that included casing removal and installation as well as drilling, with an average of 154 dB re 1μPa during the course of the project. When the NMFS Technical Guidance (2016) was published, in recognition of the fact that ensonified area/volume could be more technically challenging to predict because of the duration component in the new thresholds, we developed a User Spreadsheet that includes tools to help predict a simple isopleth that can be used in conjunction with marine mammal density or occurrence to help predict takes. We note that because of some of the assumptions included in the methods used for these tools, we anticipate that isopleths produced are typically going to be overestimates of some degree, which may result in some degree of overestimate of Level A harassment take. However, these tools offer the best way to predict appropriate isopleths when more sophisticated 3D modeling methods are not available, and NMFS continues to develop ways to quantitatively refine these tools, and will qualitatively address the output where appropriate. For stationary sources in-water pile driving/removal and drilling activities from the Navy's proposed project, NMFS User Spreadsheet predicts the distance at which, if a marine mammal remained at that distance the whole duration of the activity, it would incur PTS. Inputs used in the User Spreadsheet are reported in Table 1 and sources levels used in the User Spread are reported in Table 5, and the resulting isopleths are reported in Table 6 (Impact) and Table 7 (Vibratory and Drilling) below. Table 6—Level A and Level B Harassment Isopleths for Impact Pile Driving Pile driving site Source Level A—Radius to isopleth (m) LF cetaceans MF cetaceans HF cetaceans Phocids Level B—Radius to isopleth (m) Distance to Level B threshold (m) Area within Level B threshold (km 2 ) 1 Pier 4 24″ Concrete Fender 143 5 170 76 117 <0.1 CEP-175 13″ Polymeric 22 1 26 12 3 <0.1 Pier 3 24″ Concrete Bearing 160 6 190 86 117 <0.1 CEP-176 42″ Steel Pipe Bearing 934 33 1,112 500 1,000 0.4 28″ Steel Sheet 773 28 921 414 2,512 2.4 CEP-102 42″ Steel Pipe 1,002 36 1,193 536 1,000 1.4 28″ Steel Sheet 773 28 921 414 2,512 8.0 24″ Concrete Pile 143 5 170 76 117 <0.1 18″ Concrete Pile 36 1 43 19 25 <0.1 1 Area within the Level B threshold was calculated using geographic information system (GIS) data as determined by transmission loss modeling, accounting for land. Table 7—Level A and Level B Harassment Isopleths for Vibratory Pile Driving and Removal, and Pre-Drilling Pile driving site Source Level A—Radius to isopleth (m) LF cetaceans MF cetaceans HF cetaceans Phocids Level B—Radius to isopleth (m) Level B— Radius to isopleth (m) Area within Level B threshold (km 2 ) 1 Pier 4 14″ Timber (demolition) 20 2 30 12 6,310 49.9 24″ Concrete (vibratory) 5 <1 4 <1 6,310 97.8 24″ Concrete (drilling) 1 0 1 <1 1,848 4.4 Pier 3T 16″ and 18″ Concrete (demolition) 20 2 30 12 6,310 49.9 14″ Timber (demolition) 20 2 30 12 6,310 49.9 CEP-175 13″ Polymeric (vibratory) 18 2 27 11 6,310 11.1 13″ Polymeric (drilling) 1 <1 1 <1 1,848 4.4 CEP-176 42″ Steel Pipe 80 7 118 49 2 15,849 46.0 28″ Steel Sheet 43 4 64 26 13,594 39.9 CEP-102 42″ Steel Pipe 80 7 118 49 15,849 98.9 28″ Steel Sheet 43 4 64 26 13,594 90.6 24″ Concrete (drilling) 1 0 1 <1 1,848 4.4 14″ Timber 20 2 30 12 6,310 49.9 13″ Polymeric 20 2 30 12 6,310 49.9 18″ Concrete 20 2 29.7 12 6,310 49.9 1 Area within the Level B threshold was calculated using geographic information system (GIS) data as determined by transmission loss modeling. 2 Note: This value is different than that listed in the application, due to a typographic error in the application. The correct maximum distance to 120 dB RMS threshold is 15,849 m as seen here. The maximum distance to the Level A harassment threshold during construction would be during the impact driving of 42-inch steel pipe piles at CEP-102 (1,193 m for harbor porpoise; 1,001 m for humpback whale; 35.6 m for bottlenose dolphin; and 536 m for pinnipeds). The largest calculated Level B harassment zone extends out to 15,849 m, which would result from the vibratory installation of the 42-inch steel pipe pile. Marine Mammal Occurrence and Take Calculation and Estimation In this section we provide the information about the presence, density, or group dynamics of marine mammals that will inform the take calculations. We describe how the information provided above is brought together to produce a quantitative take estimate for each species. Humpback Whale Humpback whales occur in the mouth of the Chesapeake Bay and nearshore waters of Virginia during winter and spring months. Most detections during shipboard surveys were one or two juveniles per sightings. Although two individuals were detected in the vicinity of proposed project activities, there is no evidence that they linger for multiple days. Because no density estimates are available for the species in this area, the Navy estimated two takes for every 60 days of pile driving and drilling activities. Based on this information, NMFS has similarly estimated that two humpback whales may be taken by Level B harassment for every 60 days of pile driving and pre-drilling activities, which equates to 9 takes over 280 project days (Table 1). To be conservative, the Navy has requested 3 additional Level B harassment takes of humpback whales. Therefore, the Navy is requesting, and NMFS is proposing to authorize 12 takes by Level B harassment of humpback whale (Table 9). The largest Level A harassment zone for low-frequency cetaceans extends approximately 1,002 m from the source during impact driving of a 48 inch steel pipe pile (Table 6). The Navy is planning to implement a 1,010 m shutdown zone for humpback whales during impact pile driving of the 48 inch steel pipe piles, and shutdown zones that include the entire Level A harassment isopleth for all activities, as indicated in Table 10. Therefore, the Navy did not request, and NMFS does not propose to authorize Level A harassment take of humpback whale. Bottlenose Dolphin The expected number of bottlenose dolphins in the project area was estimated using inshore seasonal densities provided in Engelhaupt et al. (2016) from vessel line-transect surveys near NAVSTA Norfolk and adjacent areas near Virginia Beach, Virginia, from August 2012 through August 2015 (Engelhaupt et al., 2016). This density includes sightings inshore of the Chesapeake Bay from NAVSTA Norfolk west to the Thimble Shoals Bridge, and is the most representative density for the project area. NMFS multiplied the density of 1.38 dolphins/km 2 by the Level B harassment zone area for each activity for the project, and then by the number of days associated with that activity (see Table 8), which resulted in 14,989 takes by Level B harassment of bottlenose dolphins (see Table 9). There is insufficient information on relative abundance to apportion the takes precisely to the three stocks present in the area. We use the same approach to estimating the apportionment of takes to stock used in the previous IHAs in the area including the HRBT project (86 FR 17458; April 2, 2021), and the U.S. Navy Norfolk Rule (86 FR 24340; May 6, 2021). Given that most of the NNCES stock are found in the Pamlico Sound Estuarine, over 160 kilometers to Norfolk, the project will assume that no more than 200 of the requested takes will be from this stock. Since members of the northern migratory coastal and southern migratory coastal stocks are thought to occur in or near the Bay in greater numbers, we will conservatively assume that no more than half of the remaining takes will accrue to either of these stocks. Additionally, a subset of these takes would likely be comprised of Chesapeake Bay resident dolphins, although the size of that population is unknown. The largest Level A harassment area for mid-frequency cetaceans is less than 40 m, which is associated with impact pile driving of the 42 inch steel pipe. The Navy is planning on implementing a shutdown zone of 200 m during this activity as well as when pile driving the 24 inch concrete piles and 28 inch steel sheet piles. The Level A harassment zones for all other activities extend less than 10 m for mid-frequency cetaceans (see Table 6 and Table 7), and the Navy is planning to implement a minimum of a 10 m shutdown for all other activities not included in the list above (Table 10). Given the generally small size of the Level A harassment zones, and the Navy's shutdown plan, which includes the entire Level A harassment zone for all pile driving and drilling activities, we do not expect Level A harassment take of bottlenose dolphins. Therefore, the Navy did not request, and NMFS does not propose to authorize Level A harassment take of bottlenose dolphins (Table 9). Table 8—Bottlenose Dolphin Calculated Exposure Estimates Location Activity Production days Level A harassment area (km 2 ) Level B harassment area (km 2 ) Level A takes Level B takes 1 Pier 4 Vibratory Removal Timber Fender Piles 9 0.00001 49.9 0 620 Pre-Drilling Concrete Fender Piles 6 0.000001 4.38 0 36 Impact Drive Concrete Fender Piles 3 0.0000813 0.04 0 0 CEP-175 Impact Drive Polymeric Fender Piles 2 0.000001 0.000014 0 0 Pre-Drilling Polymeric Fender Piles 2 0.000004 4.38 0 * 12 Vibratory Drive Polymeric Fender Piles 2 0.000004 11.1 0 31 Pier 3 Impact Drive Concrete Bearing Piles 150 0.00010155 0.04 0 8 CEP-176 Impact Drive Steel Bearing Piles 55 0.00174582 0.41 0 * 31 Impact Drive Sheet Piles 55 0.00119976 2.43 0 * 184 Vibratory Drive Steel Bearing Piles 55 0.00008 45.97 0 3,489 Vibratory Drive Sheet Piles 56 0.000025 39.9 0 3,083 CEP-102 Impact Drive Steel Bearing Piles 2 0.00245817 1.37 0 * 4 Impact Drive Sheet Piles 2 0.00154729 7.96 0 * 22 Impact Drive Concrete Bearing Piles 6 0.0000813 0.02 0 0 Pre-Drilling Concrete Bearing Piles 6 0.000001 4.38 0 36 Vibratory Extraction Timber Fender Piles 3 0.00001 49.9 0 207 Vibratory Extraction Concrete Fender Piles 6 0.00001 49.9 0 413 Vibratory Extraction Polymeric Fender Piles 1 0.00001 49.9 0 69 Vibratory Drive Steel Bearing Piles 2 0.000156 98.91 0 273 Vibratory Drive Sheet Piles 2 0.000045 90.6 0 250 Pier 3T Vibratory Extraction Concrete Bearing Piles 72 0.00001 49.9 0 4,958 Vibratory Extraction Timber Fender Piles 22 0.00001 49.9 0 1,515 Total Bottlenose Dolphin Take Estimate 2 0 3 14,989 1 All Level and Level B harassment exposure estimates were calculated using a density estimate of 1.38 Engelhaupt et al. (2016). 2 The maximum distance to the Level A harassment threshold is 35.6 m resulting from impact driving 42-inch steel pipe piles. This falls within the proposed shutdown zones (see Table 10). Therefore, no Level A harassment take was requested nor proposed to be authorized for bottlenose dolphins. 3 Some piles for a few projects are listed twice, due to the contractor choosing the installation method. However only the method resulting in the most takes was counted in the take totals. In all cases, vibratory driving resulted in the most takes. Numbers with an asterisk indicate calculated takes that were excluded from the total due to duplication. Harbor Porpoise Harbor porpoises are known to occur in the coastal waters near Virginia Beach (Hayes et al., 2019). Density data for this species in the project vicinity do not exist as harbor porpoise sighting data collected by the U.S. Navy near NAVSTA Norfolk and Virginia Beach from 2012 to 2015 (Engelhaupt et al., 2014; 2015; 2016) did not produce enough sightings to calculate densities. One group of two harbor porpoises was seen during spring 2015 (Engelhaupt et al., 2016). Elsewhere in their range, harbor porpoises typically occur in groups of two to three individuals (Carretta et al., 2001; Smultea et al., 2017). Given the lack of density estimates for harbor porpoises in the proposed construction area, this exposure analysis (similar to the methods used in previous IHAs) assumes that there is a porpoise sighting once every 60 days of pile driving or drilling, which would equate to 6 sightings per year over 280 days of activity. Assuming an average group size of two (Hansen et al., 2018; Elliser et al., 2018), NMFS proposes to authorize 12 takes by Level B harassment of harbor porpoises (Table 9). Harbor porpoises are members of the high-frequency hearing group which have Level A harassment isopleths as large as 1,193 m during the 42 inch steel pipe pile installation using impact pile driving. The Navy has proposed a 500 meter shutdown zone for harbor porpoises during the aforementioned activity in addition to impact pile driving the 24 inch concrete piles and 28 inch steel sheets, as a reasonable area to observe and implement shutdowns for this small and cryptic species while avoiding an impracticable number of shutdowns. Consequently, the Navy has requested authorization of take by Level A harassment for harbor porpoises during the project. While NMFS believes that take by Level A harassment is not likely, due to the duration of time a harbor porpoise would be required to remain within the Level A harassment zone to accumulate enough energy to experience PTS, we propose to authorize 10 takes by Level A harassment as requested by the Navy (Table 9). Harbor Seal The expected number of harbor seals in the project area was estimated using systematic land- and vessel-based survey data for in-water and hauled-out seals collected by the U.S. Navy at the CBBT rock armor and portal islands from 2014 through 2019 (Jones et al., 2020). The average daily seal count from the field season ranged from 8 to 23 seals, with an average of 13.6 harbor seals across all the field seasons. The Navy expects, and NMFS concurs, that harbor seals are likely to be present from November to April. Consistent with previous nearby projects, NMFS calculated take by Level B harassment by multiplying 13.6 seals by 183, which is the number of pile driving/drilling days expected to occur from November to April, which results in 2,489 harbor seal takes. However, NMFS believes this may be an overestimate of take as recent monitoring reports from a nearby-completed project observed 0 harbor seals during the course of their project (HRCP, Unpublished ). With these new data in hand, we propose to alter our estimation method for this species and propose to authorize half of the take estimated above to achieve a more realistic number of seals that may be encountered, while still conservatively estimating noise exposures. Therefore, NMFS proposes to authorize 1,244 takes of harbor seals. The largest Level A harassment isopleth for phocid species is less than 550 m, which would occur during the installation of the 42 inch steel pipe pile by impact pile driving. We are proposing to implement a 200 m shutdown zone for this activity in addition to the installation of the 24 inch concrete piles and 28 inch steel sheet piles by impact pile driving (Table 10). Given the area of the Level A harassment zone that would exceed the implemented shutdown zone for these activities, and the cryptic nature of the species, the Navy is requesting 16 takes by Level A harassment of harbor seals. For all other activities, the proposed shutdown zones exceed the calculated Level A harassment isopleth for phocid species. Therefore, NMFS proposes to authorize 1,228 takes by Level B harassment, and 16 takes by Level A harassment of harbor seals (Table 9). Gray Seal Very little information is available about the occurrence of gray seals in the Chesapeake Bay and coastal waters. Survey data collected by the U.S. Navy at the CBBT portal islands from 2014 through 2018 (Rees et al., 2016; Jones et al., 2018) observed one gray seal in February 2015 and one seal in February of 2016, while no seals were observed at any other time. Maintaining the assumption that gray seals may utilize the Chesapeake Bay waters, the Navy conservatively estimates that one gray seal may be exposed to noise levels above the Level B harassment threshold for every 60 days of vibratory pile driving during the six month period when they are most likely to be present. The Level A harassment isopleth for phocids is noted above for harbor seals, while the largest Level B harassment zone area is anticipated during drilling for installation of the 42 inch steel pipes (~16 km 2 ). The Navy calculated a total of 3 exposures for gray seals during the course of the project and they are expected to be very uncommon in the Project area. It is anticipated that up to 20 percent of gray seal exposures would be at or above the Level A harassment threshold based on the proportion of the project's pile driving and drilling activities that could exceed the Level A harassment threshold. Therefore, the Navy is requesting, and NMFS is proposing to authorize, 1 take by Level A harassment and 2 takes by Level B harassment of gray seals (Table 9). Table 9—Proposed Authorized Amount of Taking, by Level A Harassment and Level B Harassment, by Species and Stock and Percent of Take by Stock Common name Stock Level A harassment Level B harassment Total Percent of stock Humpback whale Gulf of Maine b 0 12 12 1 Bottlenose dolphin WNA Coastal, Northern Migratory a c d 0 19,327 19,327 111 WNA Coastal, Southern Migratory a d 0 19,327 19,327 197 Northern NC Estuarine a c d 0 200 200 24 Harbor porpoise Gulf of Maine/Bay of Fundy 10 12 22 <0.01 Harbor seal WNA 16 1,228 1,244 2 Gray seal WNA 1 2 3 <0.01 a Take estimates are weighted based on calculated percentages of population for each distinct stock, assuming animals present would follow same probability of presence in the project area. Please see the Small Numbers section for additional information. b West Indies DPS. Please see the Description of Marine Mammals in the Area of Specified Activities section for further discussion. c Assumes multiple repeated takes of same individuals from small portion of each stock as well as repeated takes of Chesapeake Bay resident population (size unknown). Please see the Small Numbers section for additional information. d The sum of authorized take for the three stocks of bottlenose dolphins does not add up to the total authorized number (14989) due to rounding. Proposed 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 (latter not applicable for this action). NMFS regulations require applicants for incidental take authorizations to include information about the availability and feasibility (economic and technological) of equipment, methods, and manner of conducting 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, we carefully consider two primary factors: (1) The manner in which, and the degree to which, the successful implementation of the measure(s) is expected to reduce impacts to marine mammals, marine mammal species or stocks, and their habitat. This considers the nature of the potential adverse impact being mitigated (likelihood, scope, range). It further considers the likelihood that the measure will be effective if implemented (probability of accomplishing the mitigating result if implemented as planned), the likelihood of effective implementation (probability implemented as planned), and; (2) The practicability of the measures for applicant implementation, which may consider such things as cost, impact on operations, and, in the case of a military readiness activity, personnel safety, practicality of implementation, and impact on the effectiveness of the military readiness activity. The following mitigation measures are proposed in the IHA: • Avoid direct physical interactions with marine mammals during construction activity. If a marine mammal comes within 10 meters of such activity, operations must cease and vessels must reduce speed to the minimum level required to maintain steerage and safe working conditions, as necessary to avoid direct physical interaction; • The Navy will conduct trainings between construction supervisors and crews and the marine mammal monitoring team prior to the start of all activities subject to this IHA and when new personnel join the work, to explain responsibilities, communication procedures, marine mammal monitoring protocol, and operational procedures; and • Pile driving activity must be halted upon observation of either a species for which incidental take is not authorized or a species for which incidental take has been authorized but the authorized number of takes has been met, entering or within the harassment zone. The following mitigation measures apply to the Navy's in-water construction activities: Establishment of Shutdown Zones —The Navy will establish shutdown zones for all pile driving and removal and drilling activities. The purpose of a shutdown zone is generally to define an area within which shutdown of the activity would occur upon sighting of a marine mammal (or in anticipation of an animal entering the defined area). Shutdown zones will vary based on the activity type and marine mammal hearing group (Table 9). Protected Species Observers (PSOs) —The placement of PSOs during all pile driving and removal and drilling activities (described in the Proposed Monitoring and Reporting section) will ensure that the entire shutdown zone is visible. Should environmental conditions deteriorate such that the entire shutdown zone would not be visible ( e.g., fog, heavy rain), pile driving and removal and drilling must be delayed until the PSO is confident marine mammals within the shutdown zone could be detected. Monitoring for Level A and B Harassment —The Navy will monitor the Level B harassment zones to the extent practicable, and all of the Level A harassment zones. The Navy will monitor at least a portion of the Level B harassment zone on all pile driving, removal or drilling days. Monitoring zones provide utility for observing by establishing monitoring protocols for areas adjacent to the shutdown zones. Monitoring zones enable observers to be aware of and communicate the presence of marine mammals in the project area outside the shutdown zone and thus prepare for a potential cessation of activity should the animal enter the shutdown zone. Pre-activity 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 will observe the shutdown and monitoring zones for a period of 30 minutes. The shutdown zone will 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 zones listed in Table 10, pile driving and drilling activity must be delayed or halted. If pile driving and/or drilling is delayed or halted due to the presence of a marine mammal, the activity may not commence or resume until either the animal has voluntarily exited and been visually confirmed beyond the shutdown zones or 15 minutes have passed without re-detection of the animal. When a marine mammal for which Level B harassment take is authorized is present in the Level B harassment zone, activities may begin and Level B harassment take will be recorded. If work ceases for more than 30 minutes, the pre-activity monitoring of the shutdown zones will commence. A determination that the shutdown zone is clear must be made during a period of good visibility ( i.e., the entire shutdown zone and surrounding waters must be visible to the naked eye). Soft Start —Soft-start procedures are used to provide additional protection to marine mammals by providing warning and/or giving marine mammals a chance to leave the area prior to the hammer operating at full capacity. For impact pile driving, contractors will be required to provide an initial set of three strikes from the hammer at reduced energy, followed by a 30-second waiting period, then two subsequent reduced-energy strike sets. Soft start will be implemented at the start of each day's impact pile driving and at any time following cessation of impact pile driving for a period of 30 minutes or longer. Table 10—Shutdown Zones ( m ) During Pile Installation and Removal Pile type, size, and driving method Humpback whales Porpoises All other species Vibratory drive 14-inch timber piles 30 30 30 Vibratory drive 13-inch polymeric piles 30 30 30 Impact drive 13-inch polymeric piles 30 30 30 Vibratory drive 16-inch and 18-inch concrete piles 30 30 30 Impact drive 16-inch and 18-inch concrete piles 50 45 45 Vibratory drive 24-inch concrete piles 10 10 10 Impact drive 24-inch concrete piles 160 500 200 Vibratory drive 28-inch steel sheet piles 70 65 65 Impact drive 28-inch steel sheet piles 780 500 200 Vibratory drive 42-inch steel pipe piles 80 120 50 Impact drive 42-inch steel pipe piles 1,010 500 200 Pre-Drilling 20 500 200 Based on our evaluation of the applicant's proposed measures, as well as other measures considered by NMFS, NMFS has preliminarily determined that the proposed mitigation measures provide the means effecting the least practicable impact on the affected species or stocks and their habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance. Proposed Monitoring and Reporting In order to issue an IHA for an activity, section 101(a)(5)(D) of the MMPA states that NMFS must set forth requirements pertaining to the monitoring and reporting of such taking. The MMPA implementing regulations at 50 CFR 216.104(a)(13) indicate that requests for authorizations must include the suggested means of accomplishing the necessary monitoring and reporting that will result in increased knowledge of the species and of the level of taking or impacts on populations of marine mammals that are expected to be present in the proposed action area. Effective reporting is critical both to compliance as well as ensuring that the most value is obtained from the required monitoring. Monitoring and reporting requirements prescribed by NMFS should contribute to improved understanding of one or more of the following: • Occurrence of marine mammal species or stocks in the area in which take is anticipated ( e.g., presence, abundance, distribution, density). • Nature, scope, or context of likely marine mammal exposure to potential stressors/impacts (individual or cumulative, acute or chronic), through better understanding of: (1) Action or environment ( e.g., source characterization, propagation, ambient noise); (2) affected species ( e.g., life history, dive patterns); (3) co-occurrence of marine mammal species with the action; or (4) biological or behavioral context of exposure ( e.g., age, calving or feeding areas). • Individual marine mammal responses (behavioral or physiological) to acoustic stressors (acute, chronic, or cumulative), other stressors, or cumulative impacts from multiple stressors. • How anticipated responses to stressors impact either: (1) Long-term fitness and survival of individual marine mammals; or (2) populations, species, or stocks. • Effects on marine mammal habitat ( e.g., marine mammal prey species, acoustic habitat, or other important physical components of marine mammal habitat). • Mitigation and monitoring effectiveness. The Navy has submitted a Marine Mammal Monitoring Plan to NMFS that has been approved for this project. Visual Monitoring Marine mammal monitoring during pile driving and removal and drilling activities must be conducted by PSOs meeting NMFS' standards and in a manner consistent with the following: • Independent PSOs ( i.e., not construction personnel) who have no other assigned tasks during monitoring periods must be used; • At least one PSO must have prior experience performing the duties of a PSO during construction activity pursuant to a NMFS-issued incidental take authorization; • Other PSOs may substitute education (degree in biological science or related field) or training for experience; and • Where a team of three or more PSOs is required, a lead observer or monitoring coordinator must be designated. The lead observer must have prior experience working as a marine mammal observer during construction. PSOs must have the following additional qualifications: • Ability to conduct field observations and collect data according to assigned protocols; • Experience or training in the field identification of marine mammals, including the identification of behaviors; • Sufficient training, orientation, or experience with the construction operation to provide for personal safety during observations; • Writing skills sufficient to prepare a report of observations including but not limited to the number and species of marine mammals observed; dates and times when in-water construction activities were conducted; dates, times, and reason for implementation of mitigation (or why mitigation was not implemented when required); and marine mammal behavior; and • Ability to communicate orally, by radio or in person, with project personnel to provide real-time information on marine mammals observed in the area as necessary. The Navy must establish the following monitoring locations. For all pile driving activities, a minimum of one PSO must be assigned to the active pile driving or drilling location to monitor the shutdown zones and as much of the Level A and Level B harassment zones as possible. If the active project location includes demolition activities, then the next adjacent pier may be used as an appropriate monitoring location ensuring that the aforementioned criteria is met. Monitoring must be conducted by a minimum of two PSOs for impact driving, and a minimum of three PSOs for vibratory and drilling activities. For activities in Table 7 with Level B harassment zones larger than 3000 m, at least one PSO must be stationed on either Pier 14 or the North Jetty to monitor the part of the zone exceeding the edge of the Norfolk Naval Station (see Figure 3). The third PSO for vibratory and drilling activities would be located on Pier 1. PSOs will be placed at the best vantage point(s) practicable to monitor for marine mammals and implement shutdown/delay procedures (See Figure 3 for representative monitoring locations). If changes are necessary to ensure full coverage of the Level A harassment zones, the Navy shall contact NMFS to alter observer locations ( e.g., vessel blocking view from pier location). Monitoring will be conducted 30 minutes before, during, and 30 minutes after all in water construction activities. In addition, observers shall record all incidents of marine mammal occurrence, regardless of distance from activity, and shall document any behavioral reactions in concert with distance from drilling or piles being driven or removed. Pile driving activities include the time to install or remove a single pile or series of piles, as long as the time elapsed between uses of the pile driving equipment is no more than 30 minutes. BILLING CODE 3510-22-P EN26JA22.004 BILLING CODE 3510-22-C Acoustic Monitoring The Navy intends to conduct a sound source verification (SSV) study for various types of pile driving, extraction, and drilling associated with this proposed project. Monitoring shall include two underwater positions and shall be conducted in accordance with NMFS guidance (NMFS 2012). One underwater location shall be at the standard 10 meters from the sound source, while the other positions shall be located at a distance of at least 20 times water depth at the pile. If the contractor determines that this distance interferes with shipping lanes for vessel traffic, or if there is no other reasons why this criteria cannot be achieved ( e.g., creates an unsafe scenario for crew), the Navy's Acoustic Monitoring Plan must offer an alternate site as close to the criteria as possible for NMFS' approval. Measurements shall be collected as detailed in the Navy's application (Table 13-1) for each pile type during the entire pile-driving/extraction/drilling event. Monitoring shall be conducted for 10 percent of each t [Text truncated at 120,000 characters. The full text is on the page linked above.] --- Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2022-01474. Public record. Not legal advice.