Final_EA_13th_Street_Bridge_Replacement_Vandenberg.pdf

Final

Environmental Assessment

13th Street Bridge Replacement at the Santa Ynez River Crossing

Vandenberg Air Force Base, California

29 April 2015

30th Space Wing, Installation Management Flight 1028 Iceland Avenue, Bldg 11146

Vandenberg Air Force Base, California 93437

Environmental Assessment Page i 13th Street Bridge Replacement at the Santa Ynez River Crossing

Table of Contents

1 Purpose of and Need for the Proposed Action

1.1 Project Location

1.2 Purpose and Need

1.3 Scope of the Environmental Assessment

1.4 Interagency and Intergovernmental Coordination and Consultation

2 Description of the Proposed Action and Alternatives

2.1 Selection Standards

2.2 Alternative A: Proposed Action

2.2.1 Construction of New 13th Street Bridge

2.2.2 Demolition & Removal of Existing 13th Street Bridge

2.2.3 Installation of Fiber Optic Cable

2.2.4 Restoration of the 13th Street Bridge Project Area

2.2.5 Wetland Mitigation Area

2.2.6 Project Equipment Needs

2.2.7 Environmental Protection Measures

2.3 Alternative B: No‐Action Alternative

2.4 Other Alternatives Considered and Eliminated from Further Analysis

2.4.1 13th Street Bridge Replacement

2.4.2 Installation of Fiber Optic Cable

2.4.3 Wetland Mitigation Area

3 Affected Environment

3.1 Air Quality

3.1.1 Definition of Resource

3.1.2 Federal Requirements

3.1.3 Local Requirements

3.2 Biological Resources

3.2.1 Region of Influence

3.2.2 Methodology

3.2.3 Vegetation Resources

3.3 Waters of the United States and Wetlands

3.3.1 13th Street Bridge Project Area

3.3.2 Wetland Mitigation Area

3.4 Cultural Resources

3.4.1 Region of Influence

3.4.2 Known Cultural Resources

3.4.3 Archaeological Sites

3.4.4 Cultural Resources Studies

3.5 Earth Resources

3.5.1 Geology and Soils

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3.5.2 Seismology

3.5.3 Geological Hazards

3.6 Hazardous Materials and Waste Management

3.6.1 Hazardous Materials Management

3.6.2 Hazardous Waste Management

3.6.3 Installation Restoration Program

3.6.4 Hazardous Materials and Waste Transport

3.7 Human Health and Safety

3.7.1 Noise

3.8 Land Use and Aesthetics

3.8.1 Regional Setting

3.8.2 Project Area Setting

3.8.3 Coastal Zone Management

3.9 Solid Waste Management

3.10 Transportation

3.10.1 Region of Influence

3.10.2 Project Traffic and Haul Routes

3.11 Water Resources

3.11.1 Region of Influence

3.11.2 Surface Water and Floodplains

3.11.3 Hydraulics

3.11.4 Groundwater

4 Environmental Consequences

4.1 Air Quality

4.1.1 Proposed Action

4.1.2 No Action Alternative

4.2 Biological Resources

4.2.1 Proposed Action

4.2.2 No‐Action Alternative

4.3 Cultural Resources

4.3.1 Proposed Action

4.3.2 No‐Action Alternative

4.4 Earth Resources

4.4.1 Proposed Action

4.4.2 No‐Action Alternative

4.5 Hazardous Materials and Waste Management

4.5.1 Proposed Action

4.5.2 No‐Action Alternative

4.6 Human Health and Safety (Noise)

4.6.1 Proposed Action

4.6.2 No‐Action Alternative

4.7 Land Use and Aesthetics

4.7.1 Proposed Action

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4.7.2 No‐Action Alternative

4.8 Solid Waste Management

4.8.1 Proposed Action

4.8.2 No‐Action Alternative

4.9 Transportation

4.9.1 Proposed Action

4.9.2 No‐Action Alternative

4.10 Water Resources

4.10.1 Proposed Action

4.10.2 No‐Action Alternative

4.11 Cumulative Impacts

4.11.1 Past, Present, and Reasonably Foreseeable Future Actions in the Region of

Influence

4.11.2 Proposed Action

4.11.3 No Action Alternative

5 List of Preparers

6 List of Agencies, Organizations, and Persons Contacted

7 Bibliography

Appendices

APPENDIX A: Interagency and Intergovernmental Coordination for Environmental Planning

APPENDIX B: State Historic Preservation Office Consultation

APPENDIX C: Native American Tribal Consultation

APPENDIX D: United States Fish and Wildlife Service Consultation

APPENDIX E: National Marine Fisheries Service Consultation

APPENDIX F: Species Observed During Field Surveys

APPENDIX G: Assessment of Wetland Habitats at the 13th Street Bridge Demolition and Replacement Site and the Wetland Mitigation Area

APPENDIX H: Compensatory Mitigation and Monitoring Plan

APPENDIX I: California Coastal Commission Consultation

APPENDIX J: Notice of Availability for Public Review, Proof of Delivery/Publication, Comments Received on Final Draft, and Responses

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Figures

Figure 1‐1. Regional location of VAFB Figure 1‐2. Proposed Action Area and vicinity Figure 2‐1. Proposed layout of the new 13th Street Bridge and fiber optic cable installation Figure 2‐2. Typical representation of the prestressed concrete box girder and pier (for conceptual purposes) Figure 2‐3. New bridge design overview Figure 2‐4. Sample cross sections of approach roadways Figure 2‐5. Existing 13th Street Bridge piers; view from north‐east bank Figure 2‐6. Three of the eight existing 13th Street Bridge piers; view from south‐west bank. .. 17 Figure 2‐7. Existing north abutment: riprap, gabion baskets, concrete abutment, and steel wall.

Figure 2‐8. Conduit to be installed at a minimum of 25 ft below the riverbed under the Santa Ynez River Figure 2‐9. Alternative alignments considered during bridge design type selection Figure 3‐1. Overview of vegetation types and Waters of the U.S. within the 13th Street Bridge Project Area Figure 3‐2. Vegetation types and Waters of the U.S. within the Wetland Mitigation Area Figure 3‐3. Main access and transportation routes associated with the Proposed Action Figure 3‐4. Santa Ynez River basin 100‐year floodplain

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Tables

Table 2‐1. Alignment selection considerations from type selection of bridge design Table 3‐1. Ambient air quality standards Table 3‐2. Ambient air quality measurements Table 4‐1. Proposed Action construction emissions (tons/year) Table 4‐2. Proposed Action GHG emissions

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Acronyms and Abbreviations

30 CES/CENPL 30th Space Wing, Engineering Flight, Comprehensive Planning 30 CES/CEIEA 30th Space Wing, Installation Management Flight, Environmental

Conservation 30 CES/CEIEC 30th Space Wing, Installation Management Flight, Environmental

Compliance 30 CES/CEOIU 30th Space Wing, Operations Management Flight, Utilities 30 MDG/SGOJ 30th Space Wing, Medical Group, Bioenvironmental Engineering 30 SW/CC Commander, 30th Space Wing 30 SWP 30th Space Wing Plan AADT Annual Average Daily Traffic AB Assembly Bill ADT Average Daily Traffic AFOSH Air Force Occupational Safety and Health AICUZ Air Installation Compatible Use Zone AIRFA American Indian Religious Freedom Act AOC Area of Concern AOI Area of Interest APE Area of Potential Effects APZ Accident Potential Zone Base Vandenberg Air Force Base BASH Bird Air Strike Hazard BCC USFWS Bird Species of Conservation Concern Bldg building BMC Burton Mesa chaparral BMC/CCS mixed Burton Mesa chaparral and central coast scrub BMPs Best Management Practices CAA Clean Air Act CAAA Clean Air Act Amendments CAAQS California Ambient Air Quality Standards CADC California Avian Data Center Cal EPA California Environmental Protection Agency CAP Consolidated Accumulation Point CARB California Air Resources Board CCA California Coastal Act CCC California Coastal Commission CCR California Code of Regulations CCS central coast scrub CCS/NNG mixed central coast scrub/non‐native grassland C&D construction and demolition CDFW California Department of Fish and Wildlife

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CERCLA Comprehensive Environmental Response, Compensation, and Liability Act

CEQ Council on Environmental Quality cfs cubic feet per second CFR Code of Federal Regulations CH4 methane CIDH cast‐in‐drilled‐hole CIWMB California Integrated Waste Management Board CNDDB California Natural Diversity Database CNG compressed natural gas CO carbon monoxide CO2 carbon dioxide CSC California Species of Special Concern CSM coastal salt marsh CMU concrete masonry unit CRLF California red‐legged frog CSB County of Santa Barbara CWA Clean Water Act CY cubic yards CZMA Coastal Zone Management Act dB decibel dBA A‐weighted decibel dbh diameter at breast height DO dissolved oxygen DOD Department of Defense DOT Department of Transportation EMS Environmental Management System EO Executive Order EOD Explosive Ordnance Disposal EPA Environmental Protection Agency EPMs Environmental Protection Measures EPP Environmental Protection Plan ESA Endangered Species Act FE federally endangered FOC fiber optic cable FONSI Finding of No Significant Impact FONPA Finding of No Practicable Alternative FPCON Force Protection Conditions FR Federal Register ft foot or feet FT federally threatened FWM fresh water marsh GHG greenhouse gas GIS Geographic Information System

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GPS global positioning system GWP global warming potential HazMart Hazardous Materials Pharmacy HFC hydroflourocarbon HMMP Hazardous Materials Management Plan HS hydrogen sulfide IES Illuminating Engineering Society IICEP Interagency and Intergovernmental Coordination for

Environmental Planning ICRMP Integrated Cultural Resources Management Plan INRMP Integrated Natural Resources Management Plan IRP Installation Restoration Program km kilometer L liter LCZ Lateral Clear Zone LED light emitting diode LEED Leadership in Energy & Environmental Design LNG liquefied natural gas LOS Level of Service m meter m2 square meters MBTA Migratory Bird Treaty Act mg milligram MH maintenance hole MRC Midway Research Center MS4 Small Municipal Separate Stormwater Sewer System MSRS ManTech SRS Technologies, Inc.

N2O nitrous oxide NAAQS National Ambient Air Quality Standards NAGPRA Native American Graves Protection and Repatriation Act NCA Noise Control Act NEPA National Environmental Policy Act NG native grassland NHPA National Historic Preservation Act NMFS National Oceanic and Atmospheric Administration, National

Marine Fisheries Service NOI Notice of Intent NNB non‐native broadleaf NNG non‐native grassland NO2 nitrogen dioxide NOx oxides of nitrogen NPDES National Pollutant Discharge Elimination System NRHP National Register of Historic Places NSF National Sanitation Foundation, International

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NSR New Source Review O3 ozone OAK oak woodland OAK/BMC mixed oak woodland and Burton Mesa chaparral OSHA Occupational Safety and Health Administration Pb lead PERP Portable Equipment Registration Program PFC perflourocarbon PHV peak‐hour volume PM2.5 particulate matter less than 2.5 microns PM10 particulate matter less than 10 microns POLs petroleum, oil, and lubricants PPA Pollution Prevention Act ppmv parts per million by volume ppt parts per thousand PPV Peak Particle Velocity RCRA Resource Conservation and Recovery Act ROG reactive organic gases ROI region of influence ROW right‐of‐way RP Recommended Practice RUD ruderal RWD Report of Waste Discharge RWQCB Regional Water Quality Control Board SAIC Science Applications International Corporation SAP Satellite Accumulation Point SB Senate Bill SBCAPCD Santa Barbara County Air Pollution Control District SBCPD Santa Barbara County Planning and Development Department SBCWA Santa Barbara County Water Agency SE California State Endangered SIP State Implementation Plan SF6 sulfur hexaflouride SM single mode SNPL western snowy plover SO2 sulfur dioxide SR State Route SCCAB South Central Coast Air Basin SSPP Strategic Sustainability and Performance Plan SWFL southwestern willow flycatcher SWMP Solid Waste Management Plan SWPPP Storm Water Pollution Prevention Plan SWRCB State Water Resources Control Board TI traffic index

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TSCA Toxic Substance Control Act TSS total suspended solids TWG tidewater goby U.S. United States US 1 U.S. Highway 1 US 101 U.S. Highway 101 USACHPPM U.S. Army Center for Health Promotion and Preventative

Medicine USACE U.S. Army Corps of Engineers U.S.C. United States Code USGS U.S. Geological Survey UPS uninterruptible power system USAF United States Air Force USFWS United States Fish and Wildlife Service UXO unexploded ordnance VAFB Vandenberg Air Force Base V/C volume‐to‐capacity WIS Wetland Indicator Status WY water year

13th Street Bridge Replacement at the Santa Ynez River Crossing Page 1

1 Purpose of and Need for the Proposed Action

The United States Air Force (USAF or Air Force) proposes to construct a replacement bridge for the 13th Street crossing of the Santa Ynez River and to install fiber optic cable under the Santa Ynez River on Vandenberg Air Force Base (VAFB or Base), California. This Environmental Assessment (EA) has been prepared to evaluate the potential environmental effects of implementing the Proposed Action and identified alternatives per the National Environmental Policy Act of 1969 (NEPA), the Council on Environmental Quality (CEQ) regulations implementing NEPA (40 CFR 1500‐1508), and the U.S. Air Force’s Environmental Impact Analysis Process (EIAP) regulations (32 CFR 989).

1.1 Project Location

VAFB is headquarters for the 30th Space Wing (30 SW). The 30 SW at VAFB is the Air Force Space Command organization responsible for Department of Defense (DOD) space and missile launch activities on the west coast of the United States (U.S.). Satellites destined for polar or near‐polar orbit are launched from VAFB, and ballistic missiles are tested. The 30 SW supports West Coast launch activities for the USAF, DOD, Missile Defense Agency, National Aeronautics and Space Administration, foreign nations, and various private industry contractors. To accommodate space and missile launches, roadways are required to access all portions of base.

VAFB is located on the south‐central coast of California, approximately halfway between San Diego and San Francisco (Figure 1‐1). The Base covers 99,099 acres in western Santa Barbara County (USAF 2004) and occurs in a transitional ecological region that includes the northern and southern distributional limits for many plant and animal species.

The Santa Ynez River divides north and south VAFB, along the four miles of the river that runs through VAFB. The river is contained in the Lompoc Valley, which comprises the Santa Ynez River floodplain. The Santa Ynez River is the largest drainage basin on VAFB, draining approximately 900 square miles over a 90 mile (144.8 km) long channel.

The main proposed project site (13th Street Bridge Project Area) is located approximately three miles inland from the Pacific Ocean. The bridge is located on 13th Street within the Base boundaries and is limited to Air Force use only. Figure 1‐2 illustrates the regional location of 13th Street and the Santa Ynez River. Figure 1‐1 is a regional map, showing the roads in the area.

1.2 Purpose and Need

The existing 13th Street Bridge was constructed in 1970. It serves as the only on‐base transport route and vehicle link between the north and south portions of VAFB and is a critical transportation link to support several VAFB programs. At present, it is the only available route for transporting Delta IV and Atlas V payloads and rocket components between processing facilities and the airfield on North VAFB and space launch complexes on South VAFB. It is an essential single‐point failure node affecting numerous space programs, including satellite reconnaissance, vital to national security. The bridge is also the only route for fuel deliveries to

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South VAFB and the transport of hazardous materials, and carries essential communications and utility distribution lines between North and South VAFB.

In 1981, due to structural deficiencies and inadequacy of the foundation to accommodate standard highway loading the bridge was retrofitted. In 2002, Penfield & Smith & Bengal Engineering evaluated the structural integrity of the bridge and found that the bridge was still unsafe for normal highway loads and at significant risk of collapse during a 5‐year storm event (Penfield & Smith & Bengal 2002). During the summer of 2003, an emergency action was initiated to add micro‐piles to support the existing steel pilings that were exposed due to continued degradation of the structure (USAF 2003). Additional rock riprap was placed along both the north and south channel banks in September 2005. These temporary repairs were designed to protect the existing bridge from imminent collapse during a 5‐year storm event.

The purpose of the Proposed Action is to maintain a critical transportation link between South and North VAFB, along with the associated utilities and communication lines that are carried across the Santa Ynez River along the 13th Street Bridge. In addition, a new communication line will be installed under the Santa Ynez River adjacent to the new bridge to augment the communications capability between North and South VAFB. The need for the Proposed Action is to sustain vital infrastructure for mission support by replacing the 13th Street Bridge and upgrading existing fiber optics lines in the vicinity of the Bridge. The existing 13th Street Bridge is unsafe and at risk of failure and eventual collapse of the existing structure is unavoidable (Metcalf & Eddy, Inc., 2007). If the bridge is not replaced, space launch missions would continue to operate under the risk of potential bridge failure, which would result in: severance of physical access to South VAFB; severance of communications infrastructure; cessation of space launch missions where access and communications support is needed; and inability for VAFB to provide safety and security support to South VAFB due to lack of access and/or communication.

The implementation of a Wetland Mitigation Area will allow the Air Force to offset potential impacts to wetlands during construction and demolition by restoring degraded habitat.

13th Street Bridge Replacement at the Santa Ynez River Crossing Page 3

Figure 1‐1. Regional location of VAFB.

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Figure 1‐2. Proposed Action Area and vicinity.

13th Street Bridge Replacement at the Santa Ynez River Crossing Page 5

1.3 Scope of the Environmental Assessment

This EA identifies, describes and evaluates the potential environmental impacts that could result from the Proposed Action, reasonable alternatives to the Proposed Action, and the No‐ Action Alternative for each Proposed Action, as well as possible cumulative impacts from other past, present and planned actions on VAFB. In, addition, the EA identifies environmental permits relevant to the Proposed Action. As appropriate, the EA describes, in terms of a regional overview or a site‐specific description, the affected environment and environmental consequences of the action. Finally, the EA identifies management measures to avoid, prevent or minimize environmental impacts.

1.4 Interagency and Intergovernmental Coordination and Consultation

The Air Force implements a process known as Interagency and Intergovernmental Coordination for Environmental Planning (IICEP), which is used for the purpose of agency coordination and implements scoping requirements. Through the IICEP process, VAFB notified relevant federal, state, and local agencies; and the surrounding communities of the Proposed Action and provided them sufficient time to make known their environmental concerns specific to the action (Appendix A).

The Proposed Action is a federal undertaking subject to compliance with Section 106 of the NHPA. VAFB initiated consultation with the State Historic Preservation Officer (SHPO) under 36 CFR Part 800. VAFB determined that the Proposed Action would have no adverse effect to any properties listed in or potentially listed in the National Register of Historic Places. The SHPO has concurred with VAFB’s determination of no adverse effect to historic properties and (see Appendix B).

Executive Order (EO) 13175, Consultation and Coordination with Indian Tribal Governments, directs Federal agencies to coordinate and consult with Native American tribal governments whose interests might be directly and substantially affected by activities on federally administered lands. The Santa Ynez Band of the Chumash Indians was consulted on the Proposed Action and determined that no impacts to cultural sites would occur and a Native American monitor would be unnecessary (Appendix C).

VAFB determined that the Proposed Action may affect threatened or endangered species and consultation with the USFWS and NMFS was completed under Section 7 of the ESA (see Appendices D and E).

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2 Description of the Proposed Action and Alternatives

This chapter provides detailed descriptions of equipment needs, construction requirements, and operational parameters for the Proposed Action.

2.1 Selection Standards

Four primary selection standards were identified for the bridge replacement including:

1. Hydrology and hydraulics. This standard is informed and influenced by:

flow volume conveyed under the bridge;

water surface elevations;

spatial extent of design floods of various frequencies (return periods); and, scour potential.

2. Cost. This standard is informed and influenced by:

bridge size;

bridge type (both superstructure and substructure);

roadway length (with consideration of which sections will be strengthened, and which will be new/replaced); and, cost of on‐going bridge maintenance and maintenance of the river channel.

3. Schedule risks (environmental, constructability, demolition). This standard is informed and influenced by:

environmental/permitting difficulties, uncertainties, and risk;

constructability, including bridge type and location, access, seasonal concerns; and, facilitating demolition.

4. Performance, including the final project’s service performance to all anticipated service challenges. Performance is informed and influenced by:

hydraulic capacity; deciding this involves a combination of calculation, judgment, and cost benefit; analysis;

vertical Loads (this is a firm limit – the bridge must carry the specified vertical loads with performance prescribed by code allowables);

seismic (as with hydraulic performance, this involves a combination of calculation, judgment; and cost‐benefit analysis); at the VAFB site, this decision driver is heavily influenced by liquefaction potential and how to mitigate for it;

scour for bridge; and, scour for roadways.

2.2 Alternative A: Proposed Action

The Proposed Action consists of the following main components: construction of a new bridge on 13th Street over the Santa Ynez River and corresponding approach roads; demolition and removal of the existing 13th Street Bridge and existing approach roads; installation of a fiber optic communication cable under the Santa Ynez River, approximately 1,100 feet (ft) west of

13th Street Bridge Replacement at the Santa Ynez River Crossing Page 7 the existing bridge; restoration of areas temporarily disturbed by construction and demolition activities; and, establishment of a Wetland Mitigation Area at the Santa Ynez River Estuary to offset any potential permanent impacts to wetlands that cannot be restored within the main project area.

The Proposed Action would occur in two project areas within the lower Santa Ynez River area;

the 13th Street Bridge Project Area and the Wetland Mitigation Area. The 13th Street Bridge Project Area is defined as the area of anticipated impacts and vicinity, which includes the site of the new bridge construction and demolition of the existing bridge, relocation of utilities from the existing bridge to the new bridge, and installation of the fiber optic cable under the Santa Ynez River as depicted on Figure 1‐2. The Wetland Mitigation Area is the offsite area depicted on Figure 1‐2. It is anticipated that within this area, there would be as many as five acres of restored wetlands. Construction of the new bridge and demolition of the existing bridge is anticipated to begin in late spring or early summer 2015 and last approximately twelve to twenty months.

The Proposed Action Area encompasses approximately 141.5 acres, which encompasses 122.5 acres at the 13th Street Bridge Project Area and 19.1 acres at the Wetland Mitigation Area (Figures 1‐2). Within these areas the estimated area of impacts from the Proposed Action is

31.1 acres at the 13th Street Bridge Project Area (Figure 2‐1) and 6.9 acres at the Wetland Mitigation Area (Figure 2‐10).

Demolition and removal of the existing approach roads are estimated to begin in April 2016 and last between five and six months. Installation of the fiber optic cable under the Santa Ynez River is estimated to begin in April 2015 and last approximately four months. Restoration of areas temporarily disturbed during construction and demolition activities would begin prior to the onset of first rainy season following construction. Wetland restoration at the Wetland Mitigation Area in the Santa Ynez River Estuary would begin after construction and demolition activities for the bridge and fiber optic cable had been completed and final project impacts assessed.

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Figure 2‐1. Proposed layout of the new 13th Street Bridge and fiber optic cable installation.

13th Street Bridge Replacement at the Santa Ynez River Crossing Page 9

2.2.1 Construction of New 13th Street Bridge

2.2.1.1 Design Overview & Superstructure

The replacement bridge would be approximately 650 ft in length and 43.5 ft wide, located between 50 and 80 ft west of the existing bridge crossing the Santa Ynez River and associated riparian corridor (Figure 2‐1). The new bridge would consist of two travel lanes at 12 ft each and 8 ft shoulders and bridge rails. The new location of the bridge would require realignment of the existing approach roads to provide smooth curves leading into the north and south sides of the bridge (Figure 2‐1). The existing approach roads would be removed after the new bridge and new approach roads are in service. The new bridge would be built to Leadership in Energy & Environmental Design (LEED) “silver” specifications, meet current seismic loading standards, and carry the vehicle loadings from specialized missile/spacecraft transporters that will be utilizing the bridge in addition to normal highway loading. The new bridge would be completed and placed into service prior to the demolition of the existing bridge. Traffic on 13th Street would continue to use the existing bridge until the new bridge is completed.

The new bridge would also support utility and communication infrastructure required to support South VAFB. The elevation of the new bridge would be approximately 7 ft above the elevation of the existing bridge. There would be no increase in the water surface elevation.

Approach roads would also be raised to match the finish grade of the bridge.

The locations of the new bridge, approach roads, access and staging areas depicted in Figure 2‐ 1 are approximate and may change slightly with the final design; however all project activities will occur within the designated 13th Street Bridge Project Area and will have approximately the same anticipated footprint of impacted area, currently depicted as “access routes, staging areas, and direct impact areas” in Figure 2‐1.

2.2.1.2 Project Area Dewatering and River Diversion

Prior to commencing bridge construction or demolition, the project site would be dewatered by installing up and down stream dams and pumping the water within the project area out of the channel to the adjacent agricultural field. Integrated into the process of dewatering would be the diversion of the active river channel through culverts passing through the project site to keep soil and debris out of the river as well as preventing flowing water from flooding the column excavations. The culverts would be maintained throughout the new bridge construction period. Once dewatering is complete, the project site would be filled with clean soil and rock from an on‐base borrow pit to construct temporary roads to access the construction and demolition sites (Figure 2‐1). Once the temporary access roads have been completed, additional dewatering may need to occur during the installation of the bridge foundations. This water will also be pumped to the adjacent agricultural field within the project area.

2.2.1.3 Bridge Foundation, Girder, and Piers

The bridge superstructure would be haunched cast‐in‐place, prestressed concrete box girder (Figure 2‐2). The bridge cross section shall have 40 ft clearance between the bases of the traffic

Page 10 Environmental Assessment sides and crowned with two percent slopes (Figure 2‐2). The new bridge will be supported by two intermediate piers in the river bed, each consisting of 10 ft diameter drilled/cast‐in‐place concrete, approximately 200 ft deep, and an abutment at each end of the bridge, near the edges of the river bed, each supported on three 5 ft diameter drilled/cast‐in‐place concrete piles, approximately 100 ft deep. There will be two foundation piers total, both within the river bed, between 200 and 270 ft apart (Figure 2‐3) as opposed to the current bridge, that has eight piers spaced 60 ft apart. The native material at the project site will require 210 ft deep foundations for both the piers in the river bed. These foundations will be 10 ft diameter columns, cast‐in‐drilled‐hole shafts, likely installed with the use of temporary casings. The two piers will be non‐equilaterally hexagonal, with the narrowest sides facing upstream and downstream. The piers will be tapered from the bottom to the top of the bridge (Figures 2‐2 and 2‐3). There will be no scour protection needed at the piers since fewer piers will reduce the scour potential and velocity of flows under the bridge. This will differ from the current piers on the existing bridge that have riprap scour protection which impacts the natural flow of the river.

Construction will include the erection of falsework in the dewatered river bed to form and cast the new bridge deck. Falsework support posts will likely consist of steel pipes that are vibrated into the ground. Falsework would remain in place during the rainy season if bridge deck construction has not been completed and will be designed to withstand a 5 year flood.

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Figure 2‐2. Typical representation of the prestressed concrete box girder and pier (for conceptual purposes).

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Figure 2‐3. New bridge design overview: A) bridge rendering; B) refined design – profile view; C) refined design – top view.

A

B

C

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2.2.1.4 Protection of Banks and Abutments

The abutments will be anchored at the top of the slopes on the north and south banks and located as such to create a superstructure with balanced end spans. The existing banks and the new approach fills would be protected from erosion and scour. The new north abutment would be protected by adding approximately 12.5 linear ft of rock riprap, as well as leaving the existing rock riprap, gabion baskets, concrete, and steel wall associated with the existing north abutment in place. The south abutment would be protected by installing approximately 12.5 ft of new ungrouted rock riprap at the base of the abutment. The embankments for the new approach roadways would also receive rock slope protection. The rock slope protection for the new approach roadways would be soil capped and planted with interspaced native vegetative, including willow cuttings, installed during construction. The rock riprap would be embedded below the toe of the bank and soil would be excavated and removed from the embankments to place the rock riprap. A layer of excavated soil, mixed with native plant material, would be placed on top of the excavated embankments to promote native plant growth. Excess material would be transported to a designated waste or fill site. Filter fabric would be placed below the rock to prevent it from settling and becoming ineffective in protecting the banks. The layout, composition, and thickness of the filter fabric would allow tree root growth. Native willow trees would emerge among the rock riprap to create cover for habitat. Root systems of the plants help to bind stream banks in place and provide additional bank stabilization.

2.2.1.5 Bridge Lighting

Lighting fixtures may be installed on the new bridge. If so, eight 30 ft tall light poles would be located along the edge of the east side of the bridge at 83.3 ft apart. The poles would be fitted with light‐emitting diode (LED) fixtures that would provide an average of 0.4 foot candles (fc) over the entire bridge to satisfy the Illuminating Engineering Society (IES) Recommended Practice (RP) 8‐00 (RP‐8‐00; American National Standards Institute, Inc., and IES North America 2005). The design of the light fixtures would cut‐off backlight to minimize light spill behind the fixture and would not exceed 0.2 fc at the bridge edge nor exceed 0.1 fc within 10 ft north or south of the bridge edge. The maximum illumination at the ground level below the bridge would not exceed 0.1 fc. Deck‐mounted lights were considered during the design process, however pole mounted lights were justified as a more efficient and effective option due to lower cost and the creation of more uniform light levels across the bridge surface.

2.2.1.6 Associated Infrastructure

The existing bridge supports communication lines, an electrical line, a water line, and a natural gas line servicing South VAFB. These lines would remain in service until they are replaced on the new bridge. The new bridge will accommodate a 10 inch water main, four‐inch natural gas conduit, communication conduits, and a low voltage electrical line to power bridge lighting.

Full size access maintenance ports will be required at both ends of the bridge as well as at intermediate locations on the bridge. In addition to the communication line that will be replaced on the new 13th Street Bridge, an alternate, underground communications link will be installed under the Santa Ynez River (Section 2.1.3) to ensure continued reliable

Page 14 Environmental Assessment communications support during bridge construction and to provide a redundant communications link to South VAFB to support mission critical programs.

2.2.1.7 Temporary Construction Access Roads, and Staging Areas

Staging areas would be established on the terrace above the riparian corridor for storage of equipment, materials, and temporary personnel facilities and office trailers, as well as establishing a dewatering area with berms and a percolation reservoir (Figure 2‐1). A vehicle wash area with containment would also be put in the staging area. Temporary access roads would be constructed into the riparian corridor and riverbed to enable construction equipment, materials, and temporary supports to be moved into position for utilization during construction.

The temporary access roads would be installed across the riverbed on both sides of the proposed new bridge location and be approximately 50 ft wide to accommodate cranes and other construction equipment (Figure 2‐1). Clean soil, gravel, and shale would be used for the access roads to construct a firm surface capable of supporting travel by heavy construction equipment. A partial trestle might also be constructed to provide additional access and support during bridge construction. The trestle will be designed to withstand a five to ten year flood event and may be left in place over the rainy season if construction has not been completed prior to the onset of a significant rainfall event (0.5 inches during a 24 hour period) and if acceptable to the Regional Water Quality Control Board and US Army Corps of Engineers. Prior to the construction of access roads and staging areas, vegetation within the Project Area would be cleared. To the extent feasible, vegetation would be removed mechanically; however hand clearing would be required in sensitive areas, as determined by the VAFB biologists or on‐site qualified biological monitors.

All temporary fill, water diversion, and materials placed in the river channel would be removed prior to the onset of a rainfall event greater than 0.5 inch, with the possible exception of the falsework and the trestle. If necessary, in‐channel construction would recommence in spring 2016 with the re‐installation of access roads into the channel.

2.2.1.8 Approach Roadways

New approach roadways would be constructed on the north (approximately 950 ft) and south (approximately 880 ft) ends of the new bridge (Figure 2‐1). Compacted backfill materials (sand, native fill, and roadbase) would be used to raise the approach roads from existing elevation to approximately 45 ft above sea level, or 10 ft above existing grade on the north and south banks, to meet the elevation of the new bridge. The finished two lane roadways would be between 45 and 48 ft wide, six inches of asphalt over 11 inches of aggregate base, with rock slope protection, or equivalent armorflex type protection, over non‐woven filter fabric installed on 2:1 slopes on either side of the raised approach roadways (see example cross sections in Figure 2‐4).

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Figure 2‐4. Sample cross sections of approach roadways.

2.2.2 Demolition & Removal of Existing 13th Street Bridge

2.2.2.1 Overview

The existing 13th Street Bridge over the Santa Ynez River was constructed in 1970 to replace the bridge that washed out in the 1968‐1969 winter flood. The existing bridge is 500 ft long and the superstructure consists of 9 spans of reinforced concrete “T” beams (Figures 2‐5 and 2‐6).

The bridge is supported by 8 reinforced concrete pier walls. Each of the piers is supported by a single row of approximately 59 ft long steel piles. The abutments are reinforced concrete and

Page 16 Environmental Assessment are also supported by steel piles. The existing bridge is 36 ft wide between barriers and has a 4 ft wide, 2 inch thick sidewalk. A sidewalk replacement is not included in the new bridge design because the new bridge is not located within a developed area of the Base and is not a walking route. The total bridge width from outside of the bridge railing is approximately 42.5 ft.

2.2.2.2 Demolition & Removal Process

After completion of the new bridge, the existing bridge and approach roadways would be demolished and removed. Demolition would occur during the dry season (spring 2016 to the onset of significant rainfall). Prior to commencing demolition, the project site would again be dewatered, in the same manner as described in Section 2.1.1.2, by installing up and down stream dams and pumping the water within the project area out of the channel to the adjacent agricultural field. Integrated into the process of dewatering would be the diversion of the river through culverts passing through the project site spanning approximately 100 ft upstream and downstream of the project site. Once dewatering is complete, the project site would be filled with clean soil, gravel, and shale to construct temporary roads to access the demolition sites (Figure 2‐1).

The existing approach roads, including the subbase, base, and bituminous surfacing, would be removed to a depth of at least 6 inches below the grade of the existing surfacing. Where no longer needed, the associated metal beam guard railing would be removed, along with any concrete anchors and steel foundation tubes. Holes and depressions left as a result of removal of the approach roads and railings would be backfilled with clean fill and graded to blend with the surrounding terrain. Demolition of the existing bridge would be accomplished utilizing an impact hammer mounted to a hydraulic excavator, a 90 pound jackhammer, and concrete saw.

Explosives will not be used during the demolition process. Temporary support shoring, temporary bracing, and protective covers would be installed to support portions of the bridge as the existing support structures are removed during the demolition process. Protective shields would be used to contain debris during demolition and prevent it from falling into the river channel. Protective shields would be at least equal to 2 inch Douglas fir planking on posts at 5 ft centers. Piling, piers, abutments, and pedestals would be removed to 3 ft below the ground line or 3 ft below finished grade, whichever is lower. The concrete bridge abutments and piers would be removed in their entirety. The riprap at the base of the pilings, within the river channel, and at the piers at the south abutment will be removed in their entirety. The north abutment and associated riprap, gabion baskets, and concrete wall at the base of this abutment would be removed in their entirety (Figure 2‐7).

Existing north abutment riprap, gabion baskets, concrete abutment, and steel wall will be removed and re‐used for the new bridge construction (see Figure 2‐7). Remaining debris would be segregated and diverted for reclamation and disposal at an offsite landfill.

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Figure 2‐5. Existing 13th Street Bridge piers; view from north‐east bank.

Figure 2‐6. Three of the eight existing 13th Street Bridge piers; view from south‐west bank.

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Figure 2‐7. Existing north abutment: riprap, gabion baskets, concrete abutment, and steel wall.

2.2.3 Installation of Fiber Optic Cable

Fiber optic cables attached to the existing 13th Street Bridge are an essential communications link between launch platforms on South VAFB and launch control centers on North VAFB.

Interruption of the main communication supply could cause a delay or other mission impact to space launches. A redundant, secure communications link is needed to ensure reliable communications support to mission essential facilities on South VAFB.

The Combat Information Transport System (CITS) upgrade along 13th Street completed in 2008 improved reliability via dual connectivity and eliminated existing network maintenance issues.

An existing CITS fiber optic cable runs across the existing bridge and would be reinstalled on the new bridge. A Biological Opinion was issued for the CITS project in 2006 (USFWS 2006). A second existing overhead fiber optic cable, approximately 1,100 ft downstream of the existing 13th Street Bridge, has been found to be vulnerable. A new underground fiber optic cable would be installed near the same location as the existing overhead cable to maintain reliability of communications and address security concerns. Activities associated with the installation of the new fiber optic cable could occur at any time of the year, but would begin in spring 2015.

2.2.3.1 Maintenance Holes

Three new maintenance holes (MH‐A, MH‐B, and MH‐C; Figure 2‐1) will be installed at each bore hole site (approximate locations shown on Figure 2‐1). Maintenance holes would be

Environmental Assessment Page 19 precast and have a minimum interior dimension of 3 ft by 5 ft by 4 ft (width, length, depth) and be equipped with a sump, pulling irons and cable racks and torsion assisted rectangular diamond plate covers with self‐latching stainless steel slam locks.

2.2.3.2 Underground Conduit Installation

Four separate 2 inch diameter high density polyethylene SIDR 11 conduits would be installed via one directional drilling/boring (approximate locations shown on Figure 2‐1). The bore diameter would be 12 inches. All ducts would have a sleeve or bell end type coupling and would be watertight when assembled. With the exception of the Santa Ynez River crossing, all conduits would be installed at a minimum of 60 inches below grade. The new conduit would be installed starting at handhold (HH)‐1 along 13th Street north of the bridge and paralleling the road until it intercepts the newly installed MH‐A. The conduit route would then cross VAFB agriculture fields to intercept existing MH‐1 approximately 700 ft north of the river. From MH‐ 1, conduit will be bored under Santa Ynez River, between MH‐1 and new MH‐B, at a minimum of 25 ft below grade (as shown in Figure 2‐8) and an approximate distance of 1,100 ft. From MH‐B, conduit will be bored southwest under agricultural fields to intercept new MH‐C, northwest of the intersection of Highway 246 and 13th Street and then finally bored to intercept existing MH‐2 on the east side of 13th Street. The total length of conduit to be installed is approximately 5,500 ft.

Figure 2‐8. Conduit to be installed at a minimum of 25 ft below the riverbed under the Santa Ynez River.

2.2.3.3 Fiber Optic Cable Installation

Two separate Single Mode (SM), outside plant fiber optic cables (FOC) would be installed into the new conduit system. Each cable would be run through the same conduit but separate innerducts.

2.2.4 Restoration of the 13th Street Bridge Project Area

After construction and demolition is completed within the 13th Street Bridge Project Area, restoration efforts would be implemented within areas temporarily disturbed by construction activities. The proposed restoration areas are shown on Figure 2‐9.

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Disturbed areas would be restored to an ecologically functional state that supports the same local plant and animal species found in adjacent natural areas. Native plant species were selected on the basis of providing conditions that facilitate soil deposition, nutrient cycling, plant succession, natural regeneration, wildlife movement, and erosion control. Long‐term maintenance (e.g., weeding and plant replacement) and monitoring would ensure the successful restoration of native plant communities and wetland habitats to the maximum extent possible. More detailed information on the work and/or Environmental Protection Measures associated with these efforts is discussed in Section 2.2.7.

A Comprehensive Mitigation and Monitoring Plan would be implemented following construction and demolition activities and be implemented at both the 13th Street Bridge Project Area and the Wetland Mitigation Area. The plan will include post‐construction monitoring to assess the effectiveness of the initial native plant revegetation efforts and provide guidance for follow‐up maintenance, based on performance criteria described in the plan. The post‐construction monitoring would focus on the extent of native species cover and the diversity and presence of non‐native, invasive plant species. Eradication of invasive plants, through hand removal, mechanical removal (e.g. weed wacker), and herbicide application, is anticipated to be necessary throughout the monitoring period. The project area would be assessed on a monthly basis for watering needs and for the presence of nonnative, invasive plant species. Native plantings would be irrigated as necessary with water from the VAFB water supply, thus lightly chlorinated, or from the Santa Ynez River. Water from the Santa Ynez River would be pumped into containers for hand‐watering or into a drip irrigation system. The irrigation pump intake would be placed in a 30 gallon barrel with fine mesh (1/16th inch) screened holes by a qualified biologist to protect listed species from entering the pump intake.

2.2.4.1 Construction Site Restoration

Restoration of the area impacted during the installation of the new bridge would begin during the final stages of all construction activities as access roads are removed and construction machinery and materials are removed. All access roads, surplus and waste materials, and temporary facilities would be removed from the Project Area, unless they are also required for the demolition of the existing bridge. To the extent feasible and practicable, the site contours, river channel, and habitat types would be restored to pre‐construction conditions. Prior to removal of access roads, a backhoe would be used to assist in the installation of willow cuttings at or near the water table along both banks of the channel. A water stinger would be used to install pole cuttings at 5 to 8 ft deep on the banks of the channel, near riprap, and in other locations where a backhoe cannot access. The water stinger will utilize water pumped from the Santa Ynez River to operate. The water pump intake would be placed in a 30 gallon barrel with fine mesh (1/16th inch) screened holes by a qualified biologist to protect fish and wildlife from entering the pump intake. All access roads that are not needed for the demolition of the existing bridge would be removed. All exposed soil areas, including upland staging and access areas, would be stabilized with vegetation. An upland seed mix that is approved by the base botanist would be applied. Weed‐free mulch would be used to protect the seed and provide temporary stabilization. Irrigation would be used in upland areas as needed to achieve the establishment of 70 percent surface vegetation coverage.

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2.2.4.2 Demolition Site Restoration

Site restoration would begin at the completion of the demolition and removal of the existing bridge. Any remaining access roads, surplus and waste materials, and temporary facilities would be removed from the Project Area. To the extent feasible, the site contours, river channel, and habitat types would be restored to mimic the surrounding natural conditions. As access roads would be removed, construction equipment (e.g. backhoe) would be used to install willow cuttings at or near the water table along the banks of the channel. A water stinger would be used to install willow pole cuttings at 5 to 8 ft deep on the banks of the channel, near riprap, and in other locations where a backhoe cannot access. The water stinger will utilize water pumped from the Santa Ynez River to operate. The water pump intake would be placed in a 30 gallon barrel with fine mesh (1/16th inch) screened holes by a qualified biologist to protect fish and wildlife from entering the pump intake. Any remaining disturbed areas would be restored to native vegetation under direction of VAFB biologists or on‐site qualified biological monitors.