10-CHRI_Wharf_Bulkhead_Final_Environmental_Assessment_EA-NPS_05-2019.pdf

US Department of the Interior National Park Service

Christiansted National Historic Site US Virgin Islands

Replace the Existing Wharf Bulkhead Environmental Assessment

May 2019 i

Table of Contents

Chapter 1: Purpose of and Need for Action

Purpose of and Need for Action Goals and Objectives Project Area Significance of the Project Area Issues and Resource Topics Dismissed from Detailed Analysis

Wetlands and Floodplains Water Quality Air Quality Soundscape Management Historic Structures Cultural Landscape and Viewshed Human Health and Safety

Chapter 2: Alternatives Description of the Alternatives

No-Action Alternative Proposed Action/NPS Preferred Alternative

Alternatives Considered but Dismissed from Detailed Analysis Mitigation Measures

Chapter 3: Affected Environment Marine Resources

Coral Benthic Habitat Essential Fish Habitat

Special-Status Species Archeological Resources Visitor Use and Experience

Chapter 4: Environmental Consequences General Methodology Past, Present, and Reasonably Foreseeable Actions Marine Resources

No-Action Alternative Proposed Action/Preferred Alternative

Special-Status Species ii

No-Action Alternative Proposed Action/Preferred Alternative

Archeological Resources No-Action Alternative Proposed Action/Preferred Alternative

Visitor Use and Experience No-Action Alternative Proposed Action/Preferred Alternative

Chapter 5: Consultation and Coordination The Civic Engagement / Public Involvement Process

Elected Officials Agencies Other Interested Parties Agency Consultation

List of Preparers and Consultants National Park Service, Christiansted National Historical Park National Park Service, Denver Service Center EA Engineering, Science, and Technology, Inc., PBC

References iii

List of Appendices

Appendix A: Mitigation Measures

Appendix B: Life History Information for Essential Fish Habitat Species

Appendix C: Potential Impacts from Noise Associated with Steel Sheet Pile Installation

Appendix D: Summary of Potential Impacts for EFH-Designated Species

Appendix E: Draft Memorandum of Agreement

List of Figures

Figure 1. Project Location Map

Figure 2. Proposed Action

Figure 3. Cast-in-Place Concrete Bulkhead Design

Figure 4. Steel Sheet Pile Bulkhead Design

Figure 5. Benthic Habitat Cover

Figure 6. Location of Long Reef

List of Tables

Table 1. Size Distribution and Abundance of Coral Species Observed on Bulkhead

Table 2. Benthic Habitat Cover

Table 3. Life Stage Presence for Species with Designated EFH in the Vicinity of the Project Area

Table 4. Special-Status Species Potentially Present in the Project Area

Table 5. Recent Monthly Visitation to Christiansted National Historic Site

Table 6. Cumulative Project List iv

Acronyms and Abbreviations

BMP Best management practice

Christiansted NHS or park Christiansted National Historic Site CFMC Caribbean Fishery Management Council CFR Code of Federal Regulations cm Centimeter

EA Environmental Assessment EFH Essential Fish Habitat ESA Endangered Species Act m Meter MOA Memorandum of Agreement

NEPA National Environmental Policy Act of 1969, as amended NHPA National Historic Preservation Act of 1966 NMFS National Marine Fisheries Service NOAA National Oceanic and Atmospheric Administration NPS National Park Service NRHP National Register of Historic Places

PBO Programmatic Biological Opinion on Threatened Caribbean Coral

Research, Restoration and Relocation

SHPO State Historic Preservation Office

TSS Total suspended solids

USACE US Army Corps of Engineers USC US Code USFWS US Fish and Wildlife Service

VIDPNR Virgin Islands Department of Planning and Natural Resources

CHAPTER 1: PURPOSE OF AND NEED FOR ACTION

The National Park Service (NPS) proposes to replace the existing wharf bulkhead along the Christiansted National Historic Site (Christiansted NHS or park) waterfront. Christiansted NHS is located in the historic town of Christiansted on the island of St. Croix, US Virgin Islands (figure 1). The goal of the proposed action is to prevent damage from more frequent and more powerful seasonal hurricanes and to mitigate and remediate the effects of historic and continuing storm damage to the Christiansted NHS waterfront landscape, associated historic buildings, visitor use, and marine vessel operations.

The existing wharf bulkhead structure, which had protected the historic waterfront from wind-driven wave action and storm damage has deteriorated considerably. Local failures in the bulkhead have rendered the artificial structure ineffective, unsound, and unsafe for vehicular or marine vessel use. Water movement is expected to continue to undermine the bulkhead, causing erosion of the shoreline. These issues, in conjunction with projected sea-level rise, would continue to exacerbate the deterioration of the existing bulkhead and further threaten the park historic landscape and cultural resources.

The proposed action would replace the existing bulkhead by encapsulating it; new steel sheet piling or new cast-in-place concrete would be installed seaward of the existing alignment. The proposed action would also include a new concrete cap (at a similar height to the existing bulkhead), new concrete fascia to protect the “splash zone,” new mooring cleats, a new fendering system, and rehabilitation of the existing concrete apron (the sidewalk adjacent to the bulkhead).

This environmental assessment (EA) has been prepared in accordance with the National Environmental Policy Act of 1969, as amended (NEPA), and implementing regulations, 40 Code of Federal Regulations (CFR) Parts 1500–1508, NPS Director’s Order 12: Conservation Planning, Environmental Impact Analysis, and Decision-making (NPS 2011) and the accompanying handbook (NPS 2015a). Compliance with Section 106 of the National Historic Preservation Act of 1966 (NHPA), as amended, is being conducted concurrently with the NEPA process.

PURPOSE OF AND NEED FOR ACTION

The purpose of this action is to replace the existing wharf bulkhead along the Christiansted NHS waterfront to protect the Christiansted NHS landscape and associated historic buildings and to restore visitor access to and appropriate use of the wharf. Action is needed at this time to prevent damage from more frequent and more powerful seasonal hurricanes and to mitigate and remediate the effects of historic and continuing storm damage to the park waterfront cultural landscape and visitor and marine vessel uses.

The proposed action would ensure that the integrity of the historic resources is protected and would allow for safe and appropriate visitor opportunities within the historic landscape and along the waterfront. The bulkhead itself is not historic.

The existing bulkhead was constructed with an expected life cycle of 25 years and was last refurbished in 1985. The proposed action would incorporate climate resiliency in the design, including a proposed life cycle of 40 years, to ensure that the resulting design is adaptable to anticipated future storm events with potentially greater storm intensities. The design would allow the bulkhead to handle overtopping and sustain storm washover during future storm events. The proposed action would also provide opportunities to restore or enhance access to the waterfront site from both land and water.

Figure 1. Project Location Map

Goals and Objectives

GOALS AND OBJECTIVES

Throughout the planning process, the NPS considered the following: anticipated sea-level rise over the next 40 years, the regulatory implications of the potential approaches (design, materials, and construction phases), site access from both land and water, and ways to accommodate existing visitor uses during construction. The following guiding principles were used to evaluate the various alternatives analyzed in the EA:

• Ensuring consistency with the project purpose and need

• Choosing a design that could be permitted and would be acceptable within the current regulatory climate

• Ensuring the design proposed would be successful and appropriate for the setting

• Understanding that the shoreline has already been changed (hardened)

• Replacing the existing bulkhead while limiting impacts to the greatest extent possible

• Incorporating resiliency in the design to allow overtopping during future storm events

PROJECT AREA

The proposed project area (figure 1) includes the existing wharf bulkhead, concrete apron, and surrounding terrestrial areas. The proposed staging area for construction equipment would be located within the northeast portion of the parking lot and continue into the grass area adjacent to the parking lot (figure 2). Additionally, the barge work area extends 200 feet out (seaward) perpendicular to the face of existing bulkhead.

SIGNIFICANCE OF THE PROJECT AREA

Christiansted NHS is in the National Register of Historic Places (NRHP), listed at the national level of significance, and is considered a historic maritime landscape. Christiansted NHS contains well-preserved architectural examples including Danish Neo Classic, Renaissance revival, and Danish West Indian vernacular structures (Gjessing 1976). Construction of Fort Christiansvaern was completed in 1749, and the historic buildings at the site are between 200 and 275 years old. The location of Fort Christiansvaern, which dominates the harbor, presents a typical 18th century military fortification, and the town of Christiansted retains the scale and feeling of a 19th century West Indian port and market (Gjessing 1976).

The wharf bulkhead was designed to protect the park landscape and historic buildings. If the bulkhead is not replaced and adapted for climate resiliency, historic buildings and archeological resources could potentially be lost. Both underwater and terrestrial archeological resources are present in the project area.

ISSUES AND RESOURCE TOPICS DISMISSED FROM DETAILED ANALYSIS

The following issues and topics are not potentially significant, are not critical to choosing between alternatives, and are not controversial. Therefore, they were eliminated from further analysis in this EA. A brief rationale for dismissal is provided for each topic.

Wetlands and Floodplains

Although the proposed project includes placing new sheet pile in portions of nearshore marine bottomlands in front of the existing wharf bulkhead, there would be no measurable change in the water

Chapter 1: Purpose of and Need for Action surface elevation adjacent to the wharf bulkhead. The flood waters displaced by the proposed project would be relatively small when compared to the total water in Christiansted Harbor, and therefore, the proposed action would not result in any measurable change in flood attenuation or storage. The same storm surge protection, floodwater protection, and energy dissipation provided by the current deepwater marine zone would be provided by the new bulkhead. The NPS would continue to advise visitors of safety issues related to flooding and the risk of storms that may develop quickly. As stated in Procedural Manual 77-2: Floodplain Management, historic or archeological structures or sites whose location is integral to their significance are considered excepted actions and do not need to comply with Director’s Order 77-2: Floodplain Management. As the bulkhead supports and protects the historic wharf area, it meets the definition of an excepted action, and therefore, a Statement of Findings for floodplains is not required for this project. The impact topic of floodplains was considered but dismissed from further analysis in this EA.

The waters adjacent to the existing bulkhead are considered a subtidal deep-water marine system, consisting of the open ocean overlying the nearshore marine bottomlands and the associated shoreline.

The project area is considered subtidal and the substrate in the immediate vicinity is continuously covered with tidal waters with nearshore soft marine bottomlands comprised of unconsolidated substrate, such as sand, mud, dead coral rubble with algae, cement pieces, and extensive manmade debris. As these waters are considered subtidal deepwater marine habitat, and therefore a deepwater habitat, an NPS Statement of Findings for wetlands is not required for this project (NPS 2002). Consequently, wetlands was dismissed from detailed analysis in this EA.

The wharf bulkhead project would occur within waters of the United States and US Virgin Islands territorial seas associated with Christiansted Harbor. US Army Corps of Engineers (USACE) has regulatory jurisdiction over the Caribbean Sea in the US Virgin Islands through Section 10 of the Rivers and Harbors Act of 1899. The NPS would coordinate with the USACE to obtain a permit pursuant to Section 10 of the Rivers and Harbors Act of 1899 (33 US Code [USC] §403) and with the US Virgin Islands Department of Planning and Natural Resources (VIDPNR) Coastal Zone Management in compliance with the Coastal Zone Management Plan.

Water Quality

Short-term impacts to water quality could occur in Christiansted Harbor during construction activities at the bulkhead and in the open-water portion of the proposed action in the barge work area. If water-based equipment is used, the placement and removal of barge spuds and tugboat propeller wash would disturb bottom sediments and may cause temporary increases in suspended sediment in the barge work area.

Scouring on the marine bottomlands due to propeller wash from the barge tug propellers may also cause a temporary increase in suspended sediments. A small resulting sediment plume from the barge spuds and propeller wash would be expected to settle out of the water column within a few hours. Potential short-term impacts to water quality would be mitigated by installing a turbidity curtain around the immediate work area during in-water construction operations. This type of floating barrier is typically used to meet standards for silt control. The barrier would likely be installed in phases to contain only the immediate area of active construction in the water. The barrier would be secured to a portion of the wall, secured at either end to the existing bulkhead using a small section of steel or timber pile driven into the substrate.

This anchor pile would likely be installed in the proposed footprint of the new sheet pile to avoid additional, temporary impacts to the marine bottomlands. The turbidity curtain would be repositioned as necessary as work progresses to always contain water-based construction work.

Sediment release from upland construction associated with the sidewalk and concrete apron would not occur because any runoff would be captured and contained. The NPS would work with the design team to determine appropriate mitigation and construction best management practices (BMPs). Turbidity control, Issues and Resource Topics Dismissed from Detailed Analysis water quality management, and implementation of BMPs during construction would be carried out in accordance with all permitting and regulatory requirements (HDR 2018a). Adverse impacts on water quality, such as fuel or chemical spills and leaks, would be avoided and/or minimized through BMPs. For these reasons, water quality was dismissed from detailed analysis in this EA.

Air Quality

The 1963 Clean Air Act, as amended (42 USC § 7401 et seq.) requires federal land managers to protect air quality and to meet all federal state, and local air pollution standards. Christiansted NHS is subject to federal and US Virgin Island air regulations. National ambient air quality standards have been established by the US Environmental Protection Agency. Current standards are set for sulfur dioxide, carbon monoxide, nitrogen dioxide, ozone, particulate matter equal to or less than 10 microns in size, fine particulate matter equal to or less than 2.5 microns in size, and lead. St. Croix is currently in attainment for all criteria air pollutants (USEPA 2019). The proposed action could have a slight effect on air quality with vehicle, marine vessel, and heavy equipment operation during construction activities; however, the effects would be extremely localized. The proposed action would have negligible short-term effects on air quality; therefore, air quality is dismissed from further analysis in this EA.

Soundscape Management

During construction, human-caused sounds would increase as a result of construction activities, equipment, vehicular traffic, and construction crews. Sounds generated from construction would be temporary, lasting only as long as the construction activity. However, continuous noise abatement would be required to prevent disturbance and nuisance to visitors, residents, workers, and urban-associated wildlife. Project-related construction noise would be minimized through the use of best available noise control techniques as listed in appendix A. Construction work would be limited to daylight hours in the project area to avoid night-time noise disruption. In addition, BMPs (e.g., mufflers) would be implemented to properly maintain construction equipment to minimize noise from use of equipment.

Contractors would use sound attenuated compressors and generators, as well as vibratory hammers, instead of impact hammers. Contractors would be required to start the vibratory action slowly by using a reduced energy setting on the equipment and then increasing the vibratory energy in a progressive, slow manner until the required oscillation/frequency is achieved, which would slowly work up to the full noise level of the equipment. This would allow marine wildlife to move away from the work area before construction noise reaches maximum levels. Equipment and machinery would not exceed 85 decibels when measured at a distance of 100 linear feet. Therefore, soundscape management was dismissed from detailed analysis.

Wildlife and Wildlife Habitat – Raptors

Management goals for wildlife include maintaining components and processes of naturally evolving park ecosystems, including natural abundance, diversity, and ecological integrity of plants and animals (NPS 2006). The project area supports raptor species, including American kestrel (Falco sparverius), red-tailed hawk (Buteo jamaicensis), osprey (Pandion haliaetus), and occasionally peregrine falcon (Falco peregrinus). The construction activities of the proposed action would have short-term effects on raptors, as the noise would disrupt foraging. Construction would be limited to approximately one year and noise would be minimized to the extent possible using properly maintained equipment and sound attenuated compressors and generators. The portion of Christiansted Harbor that would be affected by the proposed project is small in comparison to the shoreline available for these raptor species for foraging. Therefore, this topic was dismissed from further analysis in this EA.

Chapter 1: Purpose of and Need for Action

Historic Structures

The proposed action would allow for the continued use of this historic site and structures. The proposed action would not adversely affect the aspects of integrity or character-defining features that make the site eligible for listing in the NRHP. The existing bulkhead was last refurbished in 1985 and is not considered a historic structure. A pre-construction site inspection would be completed, and photographic documentation would be specified to document site conditions. Vibration monitoring would also be conducted during construction to protect the historic structures. Vibration/crack monitors would be placed on historic structures in the park, and the structures would be inspected on a daily basis prior to the onset of construction activities. The historic structures would retain their character, integrity, and data potential, and no new visual impacts on the historic properties would result from the proposed action. Because there would be no new impacts on the historic setting of the historic site, this topic is dismissed from further analysis.

Cultural Landscape and Viewshed

The cultural landscape and viewshed would not change long-term at Christiansted NHS, as the height of the bulkhead would not change, and the color(s) of the new wharf installation would be selected to blend with the color effect at Christiansted NHS. Once completed, the project would have no effect on the scale and visual relationships among landscape features in the historic district, and the spatial arrangement, circulation features, and land use patterns of the historic district would remain unaltered. Short-term impacts could occur in Christiansted NHS during construction activities due to the presence of fencing, the barge, and other construction equipment, as well as the addition of construction noise. Staging areas would be established to confine storage of materials and equipment to specific locations on the site, construction would only occur during the day to reduce light pollution, and acoustic monitoring would be employed to minimize potential damage from vibration. For these reasons, cultural landscape and viewshed have been dismissed from further analysis in this EA.

Human Health and Safety

The wharf bulkhead closed in 2005 to boat operations, marine traffic, large crowds, and vehicle traffic due to safety concerns. The sidewalk at the bulkhead is closed to vehicular traffic, including vehicles for maintenance, law enforcement, and emergency response due to the degraded conditions of the concrete apron. No health or safety concerns currently exist at the site since the bulkhead is closed to marine and terrestrial vehicles. During construction, vehicle access on NPS property could be temporarily disrupted, as a portion of the parking lot at Fort Christiansvaern would be periodically closed to accommodate deliveries or movement of construction vehicles. Visitors would be excluded from the construction area but would retain access to the remaining areas of the park, including the historic buildings. These disturbances would be short-term and minor, but the NPS would prepare a traffic plan, to include pedestrians, vehicles, and marine vessels, to reduce the potential impacts on visitors, as well as businesses that use the existing wharf. As a result, human health and safety has been dismissed from further analysis in this EA.

CHAPTER 2: ALTERNATIVES

Two alternatives were chosen for detailed evaluation in this EA: the no-action alternative and the proposed action/preferred alternative. The chapter also describes other alternatives that were initially considered but dismissed from detailed analysis and presents mitigation measures for the proposed action.

DESCRIPTION OF THE ALTERNATIVES

No-Action Alternative

The no-action alternative is analyzed in the NEPA process for the review and comparison of feasible alternatives to the existing baseline conditions. Under the no-action alternative, the NPS would not replace the existing bulkhead, which was refurbished in 1985 with a life cycle of 25 years. The existing wharf bulkhead consists of approximately 500 linear feet of steel sheet piles that are in an advanced state of degradation and corrosion and approximately 200 linear feet of cast-in-place concrete that is generally in sound condition. The existing cast-in-place section of the wharf bulkhead is the section located immediately adjacent to and to the west of Fort Christiansvaern. Under the no-action alternative, the NPS would continue to use and maintain the existing facilities. Maintenance, such as mowing, wharf repair, concrete walkway repair, and management of the historic site would continue. The site’s emergency response to floods would remain unchanged, and post-flood cleanup after storm events would continue.

Some maintenance activities are common to both alternatives, such as periodic clearing of debris, clearing or cutting of vegetation, and clearing of sediment and debris along existing drainage culverts.

The NPS closed the bulkhead in 2005 to boat operations and marine traffic due to safety concerns. The current fendering system is failing, which precludes any current boat accessibility, including emergency marine response. The bulkhead was also closed to large crowds and vehicle traffic in 2005 due to safety concerns and would remain closed under the no-action alternative. The concrete apron is unable to support heavy vehicles in the current condition; therefore, the sidewalk at the bulkhead would remain closed to vehicular traffic, including vehicles for maintenance, law enforcement, and emergency response.

Under the no-action alternative, Christiansted NHS and the associated historic structures would not be protected from future storm events, including greater-intensity storm events. If the bulkhead is not replaced and adapted for climate resiliency, the existing historic buildings and the terrestrial archeological site could be permanently lost.

Proposed Action/NPS Preferred Alternative

The proposed action would replace 700 linear feet of the existing bulkhead. The new bulkhead design would have a 40-year life cycle. The existing bulkhead would be encapsulated and enclosed by the new bulkhead instead of removed. This would reduce the amount of construction debris generated that would require disposal at an upland site. Any debris removed from the construction site would be properly disposed of at an approved upland site.

Replacement of the wharf bulkhead would include: 1) removal and relocation of corals on the bulkhead and on the marine bottomlands within 15 feet of the bulkhead; 2) relocation of two isolated artifacts from the project area; 3) replacing approximately 500 linear feet of the existing steel sheet pile bulkhead with new steel sheet piles; 4) repairing approximately 200 linear feet of existing cast-in-place concrete bulkhead by pouring a new cast-in-place reinforced concrete gravity wall; 5) installing new mooring cleats and marine fenders; 6) extending the existing decking on the western end of the bulkhead to be flush with the new concrete cap; and 7) rehabilitating the existing concrete apron. These actions are described in the following paragraphs.

Chapter 2: Alternatives

Coral Relocation and Archeological Resource Protection. The proposed action would remove and relocate all coral colonies that are 5 centimeters (cm) or larger attached to the existing bulkhead and on the marine bottomlands within 15 feet of the bulkhead prior to construction. Live corals would be salvaged to the extent practicable and relocated to a designated recipient site. Corals that exhibit outward symptoms of disease would not be relocated to prevent the risk of disease transmission at the recipient site.

The proposed action would also remove and relocate two isolated artifacts from within the project area to a location outside the area of potential effects as determined by the Virgin Islands State Historic Preservation Office (VISHPO). Moving these artifacts would resolve any adverse effects from construction activities.

Bulkhead Replacement. Under the proposed action, the NPS would replace approximately 500 linear feet of existing steel sheet pile bulkhead with new steel sheet piles driven immediately (24 inches) seaward of the face of the existing bulkhead; approximately 200 linear feet of cast-in place concrete bulkhead would be repaired by pouring a new cast-in-place reinforced concrete gravity wall on top and seaward of the existing concrete bulkhead (32 inches seaward) (figure 2). The new gravity wall would be self-supported and would not require internal tiebacks (figure 3). The new steel sheet pile bulkhead would be a cantilever structural design and would have a reinforced concrete fascia and cap. The bulkhead would maintain the existing bulkhead height of +5.26 feet, which would allow the new bulkhead to handle washover during future storm events (figure 4) (HDR 2018a).

The replacement of the bulkhead would be accomplished through a combination of in-water and land-based construction. Both methods would allow the NPS to replace the bulkhead and to minimize impacts to the historic wharf. In the eastern portion of the project area, the water is shallow (approximately 2- to 3-feet deep but less than 2-feet deep in places), and there is a high prevalence of seagrasses, as well as unconsolidated dead coral rubble with algae and scattered small coral colonies (3 to 5 cm). Repair of the concrete bulkhead would be completed from the existing concrete wharf apron in this area to the extent possible. Some work would occur in a temporary work area that would extend approximately 3 feet seaward of the footprint of the new bulkhead and could include placement of the temporary form and support structures for the concrete wall. In-water construction would be used to install new steel sheet piles in the central and western portion of the study area, where the water depth is sufficient, using a vibratory hammer. Subsurface predrilling and preforming methods could be used to penetrate subsurface cemented bedrock where necessary. Construction equipment would likely consist of standard concrete placement equipment and possible land-based pile driving equipment (e.g., crane).

New mooring cleats would be installed along the top of the new bulkhead cap. Spacing of the cleats would generally match that of the existing mooring cleats (15-feet center-to-center) or as appropriate based on operational feedback provided from park staff in a future design phase. New marine fenders would also be installed. The proposed fender system would consist of typical marine fender materials affixed directly to the concrete fascia of the new bulkhead (see figure 4).

A portion of the public Christiansted boardwalk, which is comprised of timber and composite materials, at the western end of the project area would be removed; the composite decking would be stored for reuse during construction. After installation of the steel sheet piles, the timber decking would be extended to match the extent of the bulkhead’s new concrete cap. The composite decking would be used to rebuild the deck in the same location.

Figure 2. Proposed Action

Figure 3. Cast-in-Place Concrete Bulkhead Design

Figure 4. Steel Sheet Pile Bulkhead Design

Alternatives Considered but Dismissed from Detailed Analysis

The concrete sidewalk is structurally sound; however, the proposed action would rehabilitate the existing concrete apron to improve the condition of and increase the design life of the concrete sidewalk. This would include locating any potential voids beneath the existing concrete and creating a detailed plan to fill and repair the voids. Additionally, the concrete apron would be thoroughly cleaned, visible concrete damage (e.g. cracks, chips, spall, etc.) would be repaired, and an overall surface treatment would be applied during the concrete apron rehabilitation. BMPs would be employed during surface treatment application to prevent spills.

Construction Equipment, Timing, and Detours. Coral removal and relocation would occur prior to the start of construction; however, relocation would not be conducted during peak hard coral spawning or coral bleaching periods (July 1 through October 31), as established through consultation with National Oceanic and Atmospheric Administration (NOAA) National Marine Fisheries Service (NMFS) and the VIDPNR Coastal Zone Management. Construction is anticipated to take approximately 12 months.

Ground protection measures would be used in all locations where equipment would operate within the uplands along the wharf area or where materials would be placed off of paved surfaces. Areas of resource sensitivity would be marked as avoidance areas and protected from disturbance. All areas where construction equipment would be used along the historic waterfront would have ground protection to ensure minimal to no ground disturbance. Construction staging areas would be located within existing developed or disturbed areas (figure 2). Staging areas could be used for materials and construction equipment, such as a crane mounted drill rig, a vibratory hammer, a concrete mixer, and a barge.

Overall project scheduling, which would likely result in removal of the coral and archeological artifacts prior to the start of construction, could be considered a mitigation measure. With the implementation of these mitigation measures, project related impacts would be minimized. Construction would require intermittent closures of a portion of the Fort Christiansvaern parking area and the driveway to the King Christian Hotel in the western end of the site (figure 2). Vehicular access, including emergency vehicle access, would be maintained throughout the entire construction period by implementing traffic control measures, including detours and protection of open lanes. A traffic plan to include vehicles, marine vessels, and pedestrians would be prepared to manage traffic during closures.

ALTERNATIVES CONSIDERED BUT DISMISSED FROM DETAILED ANALYSIS

During the initial design process for this project, the NPS reviewed a previous engineering study (Moffatt & Nichol 2014), which had determined that repairs to the bulkhead would not be cost effective due to the stage of deterioration. This review validated that attempting to repair the bulkhead would not be cost effective at the bulkhead’s current stage of deterioration (HDR 2018b). Five design alternatives were reviewed and considered during a Value Analysis Workshop conducted in May 2018 (HDR 2018c). The following alternatives were considered for project implementation but were dismissed from further analysis because none individually met NPS objectives for replacing the bulkhead.

• Cantilever Bulkhead with a 20-year Design Life: Under this alternative, the full length of the existing bulkhead (700 linear feet) would be replaced with a cantilever metal sheet pile and would have a design life of 20 years. One of the key advantages to the cantilever design is that installation minimizes disturbance to the existing bulkhead and terrestrial resources on the upland side of the bulkhead (no anchoring required). This alternative was dismissed because bulkhead replacement would be required once every 20 years. This could cause an adverse effect on marine bottomlands during each replacement phase of the construction.

• Anchored Bulkhead with a 40-year Design Life: In contrast to a cantilever bulkhead, this alternative considered an anchored bulkhead, which uses an anchor rod as a tie-back into the soil instead of driving sheet pile into the sediment like a cantilever bulkhead. This alternative had a

40-year design life but was dismissed because the tie-back rods would disturb additional terrestrial resources landward of the existing bulkhead. Ground excavation would be required to set the rods during construction beyond the existing concrete walkway. This would potentially cause an adverse effect on cultural resources under Section 106 of the NHPA.

• Anchored Bulkhead with a 20-year Design Life: Similar to the anchored bulkhead discussed above, this alternative had only a 20-year design life. In addition to disturbing terrestrial resources while setting the rods for the anchors and potentially causing an adverse effect on cultural resources from ground disturbance, bulkhead replacement would be required once every 20 years.

For these reasons, this alternative was dismissed.

• Cantilever Bulkhead with a 20-year Design Life and a Reduced Overall Length: This alternative considered a cantilevered bulkhead to replace approximately 490 linear feet of the existing sheet pile bulkhead with a 20-year design life. This alternative was dismissed because bulkhead replacement would be required once every 20 years. This would potentially cause an adverse effect on marine bottomlands during each replacement phase of the construction;

therefore, this alternative was dismissed.

MITIGATION MEASURES

To minimize impacts related to the proposed action alternative, the NPS would implement mitigation measures whenever feasible. Subject to the final design and approval of plans by relevant agencies, mitigation measures would include, but would not be limited to, the items in appendix A.

CHAPTER 3: AFFECTED ENVIRONMENT

This chapter describes the affected environment associated with the proposed action. The descriptions of the resources provided in this chapter serve as an account of the baseline conditions against which the potential impacts of the alternatives considered in this environmental assessment are compared. The resource topics evaluated in this chapter are: marine resources, special-status species, archeological resources, and visitor use and experience.

MARINE RESOURCES

The study area for marine resources is the barge work area, approximately 140,000 square feet (3.2 acres) located in the marine bottomlands directly in front of the Christiansted NHS wharf (figure 2). Coral, benthic habitat, and essential fish habitat within the project area were evaluated through database searches, a coral survey, a protocol-level seagrass delineation, and a technical visual snorkel survey along the existing wharf bulkhead.

Coral

In September 2018 scientific divers performed in-situ coral surveys along the bulkhead fronting the Christiansted NHS wharf (figure 2). In addition to the in-situ surveys, the entire portion of the submerged bulkhead was video-graphed. A photo-mosaic of the bulkhead panels was then developed to map individual colony locations on the bulkhead.

The underwater survey identified 18 scleractinian coral species (stony corals) present on the bulkhead (table 1).

In total, the survey identified approximately 500 corals greater than or equal to 5 centimeters (cm) in size.

Because of their small size, cryptic nature, and high mortality, corals less than 5 cm were noted but not tallied. Club finger coral (Porites porites) recruits and numerous small colonies of lesser starlet coral (Siderastrea radians) and golf ball coral (Favia fragum) smaller than 5 cm were present. The Pseudodiploria species, symmetrical brain coral (Pseudodiploria strigosa) and knobby brain coral (Pseudodiploria clivosa) were the most common corals present, accounting for more than 50% of all corals observed (Dial Cordy 2019a). In April 2019, the NPS and NOAA agency partners conducted a technical visual snorkel survey along and adjacent to the wharf bulkhead and confirmed the findings of the 2018 survey. The only federally listed coral species found on the bulkhead included the lobed star coral species complex. The lobed star coral species complex is comprised of three closely related species, lobed star coral (Orbicella annularis), boulder star coral (O. franksi), and mountainous star coral (O. faveolata). Outward colony morphology is generally used to differentiate species in the field, but this is often difficult when colonies are small or encrusting (as in the case of the corals growing on the bulkhead). For this reason, and because all three star coral species are listed as federally threatened species, the discussion of the three Orbicella species is combined in this document (Dial Cordy 2019a). It should be noted that corals on the bulkhead are attached to an artificial substrate, not hardbottom substrate.

Example of photomosaic of the bulkhead wall with lobed star coral location identified

Close-up photograph of lobed star coral colony

Chapter 3: Affected Environment

Table 1. Size Distribution and Abundance of Coral Species Observed on Bulkhead

Species Size <5cm

Size 5-10cm

Size >10-50cm

Size >50 cm

Blushing Star Coral (Stephanocoenia intersepta) - 1 - - Boulder Brain Coral (Colpophyllia natans) - 3 10 5 Club Finger Coral (Porites porites) numerous 24 50 - Elliptical Star Coral (Dichocoenia stokesi) 1 4 - - Flower Coral (Eusmilia fastigiata) - - 1 - Golf Ball Coral (Favia fragum) numerous 3 - - Knobby Brain Coral (Pseudodiploria clivosa) 2 - 84 13 Lesser Starlet Coral (Siderastrea radians) numerous 9 - - Lettuce Coral (Agaricia agaricites) few 1 - - Lobed, Boulder Star, Mountainous Star Coral* (Orbicella annularis species complex) - - 19 7

Massive Starlet Coral (Siderastrea siderea) few 5 20 2 Maze Coral (Meandrina meandrites) - 3 - - Mustard Hill Coral (Porites astreoides) numerous 10 63 2 Rose Coral (Manicina areolata) - 1 - - Symmetrical Brain Coral (Pseudodiploria strigosa) 4 20 126 11 Whitestar Sheet Coral (Agaricia lamarcki) - - - 1

Totals Dozens 84 373 41 Source: Dial Cordy 2019a

* Indicates federally listed species

Benthic Habitat

On September 18-19, 2018 scientific divers performed benthic community resource surveys of the barge work area and mapped approximately 113,000 square feet (2.6 acres) of marine bottomlands habitat fronting the Christiansted NHS bulkhead (figure 5) (Dial Cordy 2019a). These benthic surveys documented submerged aquatic vegetation, seagrasses and calcareous marine algae. The existing bulkhead and surrounding area are replete with a diverse benthic community that includes multiple species of scleractinian corals, seagrasses, urchins, and other invertebrates, as well as reef fish. However, the area does not contain any NMFS-designated critical habitat for seagrass. Table 2 and figure 5 present the benthic habitat identified during the survey.

Table 2. Benthic Habitat Cover

Benthic Habitat Cover Acres of Survey Area

Percent of Survey Area

Sand/rubble with attached and/or drift algae 1.41 54.2 Exotic paddle grass (Halophila stipulacea) with attached and/or drift algae 0.74 28.3 Sand/rubble 0.23 8.8 Turtle grass (Thalassia testudinum) with attached and/or drift algae 0.21 8.2 Turtle grass (Thalassia testudinum) and stipulacea) with attached algae exotic paddle grass (Halophila 0.01 0.5

Source: Dial Cordy 2019a Note: Attached algae included calcareous green algae (Penicillus capitatus, Halimeda incrassata, and Udotea flabellum) and drift algae was comprised mainly of brown algae (Dictyota sp.).

Figure 5. Benthic Habitat Cover

Seagrass beds in the marine bottomland habitat in the project area are dominated by exotic paddle grass

(Halophila stipulacea), an exotic invasive seagrass. Turtle grass (Thalassia testudinum) and paddle grass (Halophila decipiens) are also present within this marine bottomland habitat, though only a very small amount of native paddle grass was observed. In addition to these species, there are three main species of calcareous green algae in the marine bottomland seagrass beds, Penicillus capitatus, Halimeda incrassata, and Udotea flabellum.

Large areas of seagrass dominated by monospecific beds of exotic paddle grass were observed throughout the western half of the project area. An area of turtle grass was also found in very shallow water (less than 6 feet deep) in the easternmost portion of the study area. This area of turtle grass is presently mixed with exotic paddle grass. A technical visual snorkel survey of the bulkhead wall and adjacent marine bottomland habitat noted that patchy submerged aquatic vegetation occurs starting at station 4 + 80 (figure 5) that becomes thicker moving eastward along the concrete portion of the wall. This seagrass bed is dominated by turtle grass that is anchored amongst rubble, stone, and various trash (NPS 2019a).

Eight of the 18 species of stony corals identified on the wharf bulkhead were also documented on the marine bottomlands (mustard hill coral, finger coral, massive starlet coral, lesser starlet coral, golf ball coral, blushing star coral, mountainous star coral, and symmetrical brain coral); only one colony of the federally listed mountainous star coral was noted. Large amounts of trash and debris were found throughout the marine bottomlands within the project area and most of the stony corals were found on this debris (Dial Cordy 2019a).

Large areas of sand and rubble covered with calcareous green algae, as well as drift algae comprised mainly of brown algae (Dictyota sp.), are also found throughout the project site. Urchins were also noted in the grassbeds, specifically lime urchin (Diadema antillarum), variegated sea urchin (Lytechinus variegatus), and white sea urchin (Tripneustes ventricosus). Hermit crabs were plentiful and one giant hermit crab (Petrochirus diogenes) was observed. The variegated feather duster worm (Bispira variegata) was present but not common.

Another common feature of both the sand areas and grassbeds were volcano shaped sediment structures built by the burrowing of the ghost shrimp (Callianassa sp.). Numerous bearded fireworms (Hermodice carunculata) were also observed, and presence of the giant anemone (Condylactis gigantea) was noted.

Benthic invertebrates were observed on the bulkhead walls, including lime urchin, variegated sea urchin, white sea urchin, reef urchin (Echinometra viridis), and slate pencil urchin (Eucidaris tribuloides), as well as the variegated feather duster worm and the social feather duster worm (Bispira brunnea). Benthic species play important roles in ecosystem function, such as providing a food source for commercially important marine fish species, restructuring sediments, and facilitating the decomposition of organic matter.

In close proximity to the bulkhead, the marine bottomlands contain a diversity of species. Approximately two thirds of the project do not provide high quality marine bottomlands habitat. The western portion of the project area (between stations 0 + 00 to 3 + 80) contains poor conditions for marine life with silty sandy mucky dark sediments with substantial trash component. The central portion of the project area (between stations 3 + 80 and 4 + 60) also contains poor habitat conditions with silty sandy bottom with small to large unconsolidated bottom and trash and is poorly colonized by marine life. The remaining third of the project area in eastern portion (between stations 4 + 80 and 7 + 00) provides the valuable marine bottomlands habitat with sparse to thick beds of seagrass containing turtle grass intermixed with unconsolidated dead coral rubble with algae and scattered small (3 to 5 cm) coral colonies (NPS 2019a).

Turtle grass is an important food for a variety of marine wildlife, including sea turtles, manatees, fish, and invertebrate species (IUCN 2010). Exotic paddle grass, which grows in monospecific beds in the western

Marine Resources and central portions of the project area and is intermixed with the turtle grass in the eastern portion, provides lower quality habitat. Exotic paddle grass is able to expand rapidly and outcompete native species, such as turtle grass. Exotic paddle grass is less firmly rooted in the sediment, providing less stability. Additionally, the smaller leaves of exotic paddle grass provide less shelter for fauna (Smulders et al. 2017). Species composition in areas of exotic paddle grass is likely to differ from that in areas of native seagrass beds, resulting in changes to coastal protection, productivity, habitat structure, and food availability (Smulders et al. 2017). Beds of turtle grass typically form thick mats, which stabilize the sediment, but the grasses in the project area are anchored amongst rubble, stone, and trash (NPS 2019a).

Specific water quality data are not available for the project area; however, the quality of the water column is expected to vary due to scouring and suspension of marine bottom sediments by tides and currents, and mixing of biological, chemical, and oxygen levels throughout the water column. These factors influence the phytoplankton production, as well as any potential contamination from point and non-point sources, which influence the variability of the quality of the water column in the vicinity of the project area.

Essential Fish Habitat

Essential Fish Habitat (EFH) describes the waters and substrates necessary to fish for spawning, breeding, feeding, or growing to maturity (CFMC 1998), as determined by regional fishery management councils.

The Caribbean Fishery Management Council (CFMC) manages EFH in Puerto Rico and the US Virgin Islands, and considers mangrove estuary, seagrass bed, coral reef, algal plain, sand/mud bottom, shelf break, and overlying pelagic EFH (CFMC 1998). EFH is designated within the project area for 18 coral, 2 marine invertebrate, 12 reef fish, and 7 highly migratory species. Many of these species are also of commercial importance. An EFH assessment has been prepared as part of this EA to evaluate in detail potential project-related impacts to these species.

Table 3 lists the managed species identified as potentially occurring within the project area. The species listed in table 3 were screened to evaluate the potential for those species to occur within the project area.

Identification of species of concern was accomplished in four steps: 1) EFH species were identified from the regional list encompassing Christiansted Harbor; 2) life history and EFH descriptions were compiled for each species; 3) information on the distribution of species in the project vicinity was compiled; and 4) screening of EFH species/life stages was completed based on species distribution, habitat preferences, and site conditions.

Habitat preferences can vary significantly for different species during the various life stages. To assess whether suitable habitat is present in the project area for the various marine invertebrates and fish species and their life stages with EFH designation, habitat preferences for the different life stages were identified for each species. This information is presented in appendix B for the full list of EFH species identified for Christiansted Harbor. Appendix B also presents the following information for each species, where available: general habitat type, the depth at which each is likely to occur, diets, whether the species would be seasonally present, and habitat specifics for each life stage. Current research provides limited information for certain life stages of nine species managed by the Magnuson–Stevens Fishery Conservation and Management Act. Those species for which the marine habitat within the project area is unlikely to constitute EFH were eliminated from further consideration based on parameters such as depth, benthic habitat, and habitat preferences.