Traffic noise impacts are addressed under NEPA and Caltrans policies. Therefore, traffic noise impacts and abatement measures in the form of noise barriers have been analyzed and are presented in this section. Although noise abatement for impacted receptors can be achieved through the construction of noise barriers, their presence would conflict with maintaining the spirit and beauty of the proposed bridge design options on this unique project. It is therefore recommended that noise barriers not be constructed as part of the new East Span Project, unless there is overwhelming support from adjacent communities, other public agencies, and the public at large. What follows is an acoustical analysis describing traffic noise impacts and possible abatement measures.

The noise impact analysis involved modeling for future noise levels for the five alternatives (No-Build, Retrofit Existing Structure, and the N-2, N-6, and S-4 Replacement Alternatives). Potential impacts and noise abatement approaches have been assessed for each alternative for noise-sensitive uses on Yerba Buena Island (YBI), Treasure Island (TI), and the Oakland Touchdown area. The modeled peak-noise hour levels are shown in Table 4.5-1. A detailed noise impact assessment technical report has been prepared and is available for review at locations listed in the Preface.

In general, peak-noise-hour levels resulting from Replacement Alternatives N-2, N-6, and S-4 decrease by 1dBA to 10 dBA compared to the existing condition. The causes of the decrease in modeled noise levels for the future alignment scenarios are:

• Construction of the bridge using steel-reinforced concrete will result in lower operational noise levels by eliminating radiation of sound through the bridge decks and reducing noise created by vehicles traveling over expansion joints.

• For the replacement alternatives, the eastbound and westbound lanes would be side by side rather than stacked, with the exception of the YBI viaduct and tunnel portal area. This will minimize the existing condition of traffic noise reflecting from the bottom of the upper deck.

Noise abatement consisted of determining the acoustical effectiveness of noise barriers. Noise barriers must reduce future predicted noise levels at impacted receptors by at least five dBA to be considered feasible. The feasibility criterion is not necessarily a noise abatement design goal. Greater noise reductions are encouraged if they can be reasonably achieved. Feasibility may be restricted by topography, access requirements for ramps, other noise sources in the area and safety considerations. Reasonableness of noise barriers must be evaluated as well and includes such additional factors as cost per benefited residence, absolute noise levels, change in noise levels, viewshed preservation, appearance, views of impacted residents, input from other agencies, and other social, economic, environmental, legal and technological factors. Noise insulation of residential dwellings is typically only considered when severe traffic noise impacts are predicted and normal abatement measures are not physically feasible or economically reasonable. When considering extraordinary abatement measures, it must be demonstrated that the affected activities experience traffic noise impacts to a far greater degree than other similar activities adjacent to highway facilities; i.e., private residential dwelling units will have after project implementation or noise levels of 75 dBA, L_eq^(h), or more, or the project causes a noise level increase of 30 dBA or more over predicted noise levels if no project was constructed. Because substantial noise impacts are not predicted for any project of the alternatives, noise insulation of structures was not considered.

The effectiveness of a range of soundwall heights from 1.8 to 4.9 meters (6 to 16 feet) was tested using the criteria of reducing noise levels a minimum of five dBA at the receiver. In addition, for a soundwall to be considered effective, it must interrupt the line of sight between the receiver (assumed to be 1.5 meters [5 feet] tall) and an exhaust stack of a heavy-duty truck. The truck-stack height is considered to be 3.5 meters (11.5 feet) above the roadway surface. If soundwalls are installed, they should be constructed along the outer edges of the bridge decks for maximum noise abatement effectiveness.

This section describes expected changes in noise levels for the project alternatives. Receptor locations are shown on Figures 3-12, 3-13, and 3-14 in Appendix A.

No-Build Alternative and Retrofit Existing Structure Alternative. The No-Build Alternative and the Retrofit Existing Structure Alternative will not result in any increase in traffic capacity, any change in geometry, or any change in traffic speeds. Noise levels under these alternatives would remain unchanged from existing peak-noise hour levels. Therefore, no requirement exists for a noise assessment of the No-Build Alternative and the Retrofit Existing Structure Alternative.

Replacement Alternative N-2. Replacement Alternative N-2 would lie to the north of the existing East Span alignment and transition from the retrofitted double-deck viaduct to two parallel structures over YBI. Generally, noise levels would decrease by 1 to 14 decibels, compared to the existing, No-Build, and Retrofit Existing Structure Alternatives, resulting in many of the receptors experiencing future noise levels below FHWA NAC. This would eliminate the need for noise abatement at these locations.

Yerba Buena Island. On the northern side of the bridge, two 4.27-meter (14-foot) high walls 245 meters (800 feet) long at each of the bridge decks exiting YBI would reduce noise levels 5 dBA or more and break truck-stack line-of-sight. Together, the walls would provide effective noise reduction for approximately 90 presently unoccupied residential units at Location 2. Both the U.S. Navy and the City and County of San Francisco have expressed their desire to rent out these unoccupied residential units on YBI. From Station 52+40 to Station 53+40 SW-2A and SW-2B would be 3.05 meters (10 feet) high, with a 3.66 meter (12 foot) transition area from Station 52+00 to Station 52+40. The soundwalls would need to be approximately 140 meters (459 feet) in length to provide effective noise reduction to the one residence at Location 3. On the south side of the bridge, walls 3.66 meters (12 feet) in height on both bridge decks exiting the tunnel would reduce noise levels 5 dB or more and break truck-stack line-of-sight. These walls would extend for 245 meters (800 feet) to the east of the tunnel portal. These walls would provide noise reduction for the one residence at Location 4.

Replacement Alternative N-6. Generally, noise levels resulting from Replacement Alternative N-6 decrease by 1 dBA to 14 dBA compared to the existing bridge. The lower noise levels are less than the FHWA NAC at many receptors, thus eliminating the need for abatement at these locations.

Options for Noise Abatement Materials and Treatment. Options for abating noise by using different barrier materials, tunnel portal treatments, and roadway pavement materials were reviewed for the East Span Project. These options

and their potential effectiveness are summarized below. Selection of barrier materials would be subject to evaluation of a number of factors in addition to their effectiveness in providing noise abatement. Additional factors include maintenance requirements, expected period of serviceability and life-cycle costs.

Standard Soundwall. Examples of standard materials are masonry block and precast concrete. Generally the heaviest barrier per unit dimension, it requires a slightly more massive supporting structure; the reverberant soundfield may increase noise level between closely spaced parallel soundwalls; it has potential for reflecting traffic noise into adjacent areas that are located nearby, above, and opposite from the soundwall; it is not visually transparent.

Acoustically Absorptive Soundwall. Multiple reflections between parallel barriers can potentially reduce the acoustical performance of each individual barrier. When designing reflective parallel noise barriers, it is recommended that a minimum 10:1 ratio is maintained between two barriers, in order to avoid the possibility of perceivable barrier performance degradations. If that is not possible, acoustically absorptive barriers may have to be considered. The recommended aspect ratio (10:1 or greater) could be achieved for this project and, therefore, no further noise abatement in the form of acoustically absorptive barriers would be required.

Viewshed Soundwall. These soundwalls are visually transparent noise barriers; alternative material is glass; acoustical performance equivalent to standard reflective soundwalls; substantially lighter weight per unit area than standard masonry soundwall material; reverberant soundfield may increase noise level between parallel soundwalls; has potential for reflecting traffic noise into adjacent areas that are located nearby, above, and opposite from the soundwall; panel sections designed to be readily disassembled and replaced without affecting adjacent sections or losing acoustical performance; newer generation of materials are non-yellowing/glazing to maintain visual transparency; the vertical (and optionally) horizontal framing and supporting structures are fabricated of solid material that is not transparent.

Combination Viewshed/Acoustically-absorptive Soundwall. The metal sandwich type of transportation noise panel system has provision for intermixing transparent view panels with the visually opaque, acoustically absorptive panels. The see-through panels may be inserted below, between, and/or above the solid panels. Depending on the specific combination and placement of panel types, the acoustic characteristics of the combination soundwall will be more or less similar to reflective or absorptive soundwalls; substantially lighter weight per unit area than standard masonry soundwall material; panel sections designed to be readily disassembled and replaced without affecting adjacent sections, or changing acoustical performance and visual characteristics.

Reduced Noise Pavement Surfaces. Non-standard pavement surfaces have been alleged to reduce traffic noise. The most common pavement types referred to for this effect are "open graded" asphalt concrete and "rubberized" asphalt. Although the non-acoustic properties of these pavement types are documented and standard specifications for their use are available, their benefits in noise reduction are only recently being published, with scientific research by Caltrans in process. Recently released data (Wayson, R.L., July 1998) concluded that dense asphalt is approximately 3 dBA quieter than PCC with new open graded asphalt providing an additional 1.5 dBA lower noise level. However, the data suggests that open graded noise levels will be similar to dense graded material after some years of wear. Rubberized binder asphalt may reduce pavement noise levels by approximately three decibels; however sufficient study data is not currently available to support firm conclusions. Another study (Bajdek, C., 1998) found that noise levels from open graded asphalt were approximately five decibels lower than for grooved PCC. These pavement types should be considered for use on the SFOBB project, but their noise abatement abilities must be considered along with other factors (such as life cycle cost) important to pavement type selection.

Tunnel Portal Acoustic Treatment. Noise levels in the immediate vicinity of traffic tunnel portals are noted to be higher than at some distance from the portals. Placement of acoustically absorptive materials inside the portals has resulted in reduction of higher noise levels experienced outside the portal. According to the literature, however, the benefits of tunnel portal treatment diminish substantially at distances of approximately 100 meters (328 feet). Because the nearest noise-sensitive receptors are approximately 100 meters away from the tunnel portal, the benefits of acoustic treatment of the tunnel portal for this project would likely be marginal.

As noted in the affected environment section, existing vibration levels from traffic operations (i.e., heavy-truck traffic) were below the levels of human perception at distances of more than 20 meters (65 feet) from the bridge support columns where ground-borne measurements were performed. Future operations vibration levels at nearby locations are predicted to remain below perception and criterion levels for any of the project alternatives, and would be even lower for the replacement bridge alternatives that are constructed of higher-mass concrete.

Hazardous and petroleum materials have the potential to adversely affect human health and the environment. The design, construction, and operation of the East Span Project could potentially increase the risk of adverse effects associated with hazardous and petroleum materials present within or near the construction footprint of the alternatives and the project area.

A Hazardous Wastes Assessment report has been prepared for the East Span Project and is available for review at the locations identified in the Preface.

Environmental liabilities may be associated with the acquisition of contaminated properties.

CERCLA can hold past and present owners of real property liable for the costs of site investigations and remediation (see Section 3.6.1). CERCLA provides a defense to this liability (the "innocent landowner" defense) if the owner or operator, prior to acquisition of the property, conducted all appropriate inquiry into the condition of the property ("due diligence" investigation). Where appropriate inquiry reveals no contamination at the time of acquisition, but contamination is later discovered, the purchaser could be released from liability.

No-Build Alternative. There are no impacts associated with the No-Build Alternative.

Retrofit Existing Structure Alternative. The Retrofit Existing Structure Alternative will likely affect the following sites:

• Installation Remediation (IR) Site 29, East Side Contaminated Bridge Soils - During retrofitting of the existing bents and columns, workers may encounter soils contaminated by metals associated with past bridge maintenance and operations and also by petroleum hydrocarbons.

• IR Site 8, Former Army Point Sludge Disposal Area - During retrofitting activities, exposure pathways to metals (especially beryllium and lead) due to heavy

Source: Hazardous Wastes Assessment, September 1998.

Note: ¹ Leaking underground storage tank.

Source: Hazardous Wastes Assessment, September 1998.

• SFOBB Structure - Historic use of lead-based paint on the bridge structure will be of concern during bridge retrofitting activities. Concerns include both those associated with worker health and safety and handling and disposal of contaminated materials.

With the exception of the SFOBB structure, impacts to these sites should be limited to encountering contaminated soils and related dust during construction. Groundwater is not anticipated to be encountered during construction of this alternative.

Replacement Alternatives N-2, N-6, and S-4. Construction of any of the three replacement alternatives may affect the following sites:

• IR Site 11, Former Landfill - Groundwater may be encountered if construction of the temporary east entrance to the USCG should exceed the depth of 1.6 meters (5.4 feet) to 3.2 meters (10.6 feet) below ground surface.

• IR Site 29, East Side Contaminated Bridge Soils - During removal of existing piers and construction of new piers, workers may encounter soils contaminated by metals associated with past bridge maintenance and operations and also by petroleum hydrocarbons.

• IR Site 8, Former Army Point Sludge Disposal - During construction located immediately north of the existing SFOBB, exposure pathways to metals (especially beryllium and lead) due to heavy construction traffic under dry, dusty conditions would include direct worker contact through ingestion or dermal contact. Although pesticides and semi-volatile organic compounds (SVOCs) were also detected in this area, a baseline human health risk assessment conducted in 1996 determined that the only potential concern was exposure to beryllium and lead.

• Building 270 LUST Site - Construction of a temporary detour above Building 270 may be affected by elevated concentrations of TPH/diesel in soils and the groundwater petroleum hydrocarbon plume associated with the leaking underground storage tank at this building.

• Building 204/208 LUST Site - Construction of replacement alternatives may affect a possible source of contamination at the Building 204/208 site. The former fire station/gas station site appears to be located upgradient from Building 270 (referenced above) and may be a possible source of groundwater contamination identified in the groundwater monitoring well immediately upgradient of Building 270.
• Building 40 LUST Site - Foundation, piers, or the relocated USCG access roadway would be located on ground currently occupied by Building 40, and footings for the detour spans may also occupy a portion of the ground surface of the building.

• SFOBB Structure - Historic use of lead-based paint on the bridge structure would be of concern during bridge demolition activities. Concerns include both those associated with worker health and safety and handling and disposal of contaminated materials.

In addition, Alternative S-4 would likely affect IR Site 13, Section E, Storm Water Off-Shore Sediments.

As compared to the Retrofit Existing Structure Alternative, impacts from construction on these sites could be substantial. Contamination from IR Site 29 and IR Site 8 is at or very near to the ground surface. Groundwater contamination will also likely be encountered at IR Site 11, Site 270 LUST, Site 40 LUST, and possibly from Site 204/208 LUST and the fuel lines at Building 213.

No-Build Alternative. There are no impacts associated with the No-Build Alternative.

Retrofit Existing Structure Alternative. The Retrofit Existing Structure Alternative would likely encounter contamination that was detected around the bridge footings and bents of the eastern approach to the SFOBB. Contaminants of concern include total recoverable petroleum hydrocarbons (TRPH), volatile organic compounds (VOCs), pesticides, polychlorinated biphenyls (PCBs), and metals. The historic use of lead-based paint on the bridge structure will also be a concern during retrofitting activities. Concerns include both those associated with work health and safety and handling and disposal of contaminated materials.

Replacement Alternative Alignments N-2 and N-6. Alternatives N-2 and N-6 will likely encounter contamination that was detected around the bridge footings and bents of the eastern approach to the SFOBB. Exposure to this source area may be less than for the Retrofit Existing Structure Alternative, because the alignment is shifted north of the existing Touchdown area. As such, only the southern edge of Replacement Alternative N-2 should be close enough to the footings to disturb contaminated soil. The historic use of lead-based paint on the bridge structure will also be a concern during construction and/or retrofitting activities. Concerns include both those associated with worker health and safety and handling and disposal of contaminated materials.

Replacement Alternative Alignment S-4 Alternative S-4 may affect three sites:

• Army Site #1, (western end of Burma Road) - Construction activities and demolition of existing structures in the area may pose a risk to workers through direct exposure pathways of known or suspected contaminants via ingestion, dermal contact, or inhalation.

• EBMUD Dechlorination Facility - Although no known contamination has been detected near the dechlorination tanks, construction activities may be affected by the presence of sodium bisulfite in the soil.

• SFOBB Structure - Historic use of lead-based paint on the bridge structure would be a concern during bridge demolition and/or retrofitting activities. Concerns include both those associated with worker health and safety and handling and disposal of contaminated materials.

Differences in impacts resulting from exposure to these identified contaminant sources will depend on the exact location and nature of proposed construction activities and nature and extent of contamination in these areas.

This section identifies data gaps and describes the actions necessary to characterize the known and potential contaminant sources that may be affected by the proposed SFOBB East Span Project alternatives.

The YBI area has been fairly well characterized. Once the preferred alternative has been selected, a complete and thorough data review will be conducted to identify the status of existing sites and whether any new concerns have been identified. Copies of pending reports from the Navy would be requested. Results of subsurface investigations identified currently as proposed will also be requested. Current analytical data from existing groundwater monitoring wells will also be requested and analyzed.

While the western portion of the Touchdown area along the existing East Span alignment has been fairly well studied, reasonable uncertainty about environmental conditions exists in several other areas. These areas include:

• North shore of peninsula along traffic lanes back to SFOBB Toll Plaza. This area is presently undeveloped. Historically, portions of this area were created by artificial fill from unknown dredge material from San Francisco Bay.

• East of the elevated part of existing bridge approach. This area includes a thin strip of land on both sides of the traffic lanes as far east as the toll plaza. The soil in this area may contain TPH as motor oil, SVOCs, and lead.

• Caltrans maintenance facility. Dark oil stains were observed, and a large transformer was stored in this area. No sampling has been conducted around these buildings.

• Area surrounding dechlorination tanks. This area may be the source of sodium bisulfite contamination in the soil.

Based on information reviewed for this assessment, the in-Bay sediments at the existing East Span have been initially characterized for the purposes of sediment disposal and worker health and safety during construction. This data is expected to generally reflect current conditions along the replacement alignments. The need for additional investigations in this area prior to construction will be determined in consultation with the Dredged Material Management Office (DMMO).

Prior to the implementation of the actions below, the East Span Project preferred alternative would be identified. The following information will be developed during final engineering design during development of the FEIS:

• Final determination of sites that will be fully or partially acquired; and

• Determination of specific construction activities planned on or near a potential contaminant source.

Once the preferred alternative has been selected and additional available information reviewed, a Phase II Environmental Site Investigation would be conducted for the preferred alternative to sufficiently characterize contaminant management and disposal concerns during construction, and to identify worker and health and safety issues that will need to be addressed. The Phase II investigation would be scoped to address identified contaminants of concern and would consider the nature and extent of proposed construction activities. The Phase II efforts would consider the areas identified above (i.e., data gaps) for which limited data is known. All Phase II investigation efforts would focus on developing specific information about contaminated sites that could affect construction of the preferred alternative to develop hazardous wastes specifications for inclusion in the construction bid documents. Phase II investigations will be limited to the level of investigation required to prepare sufficient contractor bid documents (e.g., contaminant management and health and safety procedures) because additional sampling and testing would be required during construction to ensure the proper management of contaminated media encountered.

Mitigation - All Build Alternatives.

Once the preferred alternative has been selected and Phase II investigations completed, mitigation of identified hazardous materials concerns would include those for the proper management and disposal of hazardous wastes encountered during construction and precautions for worker health and safety. These measures are discussed further below.

Highly contaminated soils would be disposed of in a Class I landfill. Non-contaminated soils may be disposed of in either a Class II or a Class III landfill, recycling facility, or released to the contractor for use as backfill material on site. Bay muds excavated for access dredging under all build alternatives would be disposed of at an approved in-Bay disposal site or at an upland site. In-Bay disposal would occur only with approval of permitting agencies. Consultation with the Dredged Material Management Office (DMMO) has been initiated to determine appropriate in-Bay disposal sites. Any removed materials not disposed of in-Bay would be transported to approved upland disposal sites or landfills by licensed waste haulers under state manifests or bills of lading as required.

If dewatering is required to construct new footings and piers, the footing may be hydraulically isolated from the groundwater and Bay water by using sheet piling or cofferdams. The use of these techniques would reduce the volume of groundwater that needs to be removed for dewatering.

Contaminated groundwater requires a discharge permit to a sanitary sewer or the Bay. Depending on the concentration, petroleum hydrocarbons may be removed from the dewatering discharge by passing it through an activated granular carbon system or using an air-stripping unit. Metals in the groundwater may require treatment. Treatment may be accomplished on site or off site. On-site treatment may include settling and precipitation of the metals in a portable tank unit. Treated water could be discharged while the sludge material would be tested and disposed of at a proper disposal facility. Off-site treatment of contaminated groundwater would involve transporting the water to an appropriate treatment facility.

Once the project area has been sufficiently characterized and construction activities sufficiently defined, a contaminant management plan would be developed and implemented during construction. The plan would include site-specific procedures for contaminant monitoring and identification, temporary storage, handling, treatment, and disposal of materials in accordance with applicable federal, state, and local laws and regulations.

In the event hazardous materials are unexpectedly encountered during construction, a contingency plan would be in place establishing procedures for temporary stoppage of work, securing of the area, notification of the discovery, and proper management of such materials. All procedures would be consistent with Caltrans’ guidelines and federal, state, and local laws and regulations.

Dismantling of all structures, especially the existing SFOBB, would include procedures for the identification, abatement, handling, and disposal of lead-based paint and asbestos, as well as worker health and safety. All procedures would be consistent with Caltrans’ guidelines and all federal, state, and local laws and regulations.

Workers performing activities on site that may involve contact with contaminated soil or groundwater would be required to have appropriate health and safety training. In order to reduce the risk of exposure, a Worker Health and Safety Plan would be prepared and implemented during construction by a Certified Industrial Hygienist (CIH). The Health and Safety Plan would include provisions for:

• Conducting preliminary site investigations and analysis of potential job hazards;
• Personal protective equipment;
• Safe work practices;
• Site control;
• Exposure monitoring;
• Decontamination procedures; and
• Emergency response actions.

The plan would specify mitigation of potential worker and public exposure to airborne contaminants by incorporating dust suppression techniques in construction procedures.

This section describes the relationships between project features and expected soil conditions in the project area and also describes issues related to possible seismic events.

The No-Build and Retrofit Existing Structure Alternatives would not change area topography and, as such, would not affect slope stability within the project area. Design of the Retrofit Existing Structure Alternative has been based on current soils information, and foundation improvements would reduce the risk of settlement.

The Replacement Alternatives N-2, N-6, and S-4 were developed to respond to the changing geological conditions along the general alignment, including the Bay muds, which occur as a blanket of sediments that cover the majority of the Bay bottom between Yerba Buena Island (YBI) and the Oakland Touchdown area. The entire Holocene and Pleistocene estuarine and alluvial sequence become increasingly thicker eastward from YBI to the Oakland Touchdown area. Construction of a signature tower which must be anchored to bedrock is not feasible in the eastern portion of the alignments.

Yerba Buena Island. Initial geotechnical data indicate that several slope stability-related issues could be associated with design of the land and marine tower foundations in the vicinity of YBI. These issues include: the gross stability of the east-facing slope of YBI, the temporary stability of the cut for the main tower, and the potential for slope failures in the vicinity of the west foundation for the main span.

To address the slope stability issues, geologic mapping performed on YBI would be integrated with marine exploration and laboratory testing (as it becomes available). Stability analyses for the various potential slope failure modes would be performed. It is anticipated that slope stability issues can be addressed during final design of the selected preferred alternative.

Oakland Touchdown Area. The soils at the end of the Oakland shore from the current ground elevation to 1.5 meters (5 feet) below mean sea level (MSL) are potentially liquefiable fill material. This fill is underlain by approximately 12 meters (39 feet) of soft clay and stiff clay. The potential for liquefaction exists for those fill soils that lie beneath the water table. In a seismic event, liquefaction could occur, resulting in lateral spreading of the fill material. The fill could also settle (without liquefaction) during a seismic event. If an earth fill option is chosen for creating an at-grade approach structure, embankment fill would be placed on certain sections of the landfall that may be prone to settlement due to consolidation of the soft clay.

To compensate for potential settlement at the Oakland Touchdown area, wick drains and a surcharge could be provided to accelerate the consolidation process of the new embankment fill. The existing soil serving as the future roadway might require design considerations such as ground modification in the form of stone columns, compaction, or similar methods to reduce the risk of unacceptable settlement and/or lateral spreading.

The project area will likely experience strong to very strong seismically induced ground shaking within the design life of all build alternatives. Under all replacement alternatives, some damage to bridge components would be expected to occur during a major seismic event; however, the components should still be able to perform their design functions. In general, strong ground shaking can cause one or more of the following:

• Densification of loose granular soils

• Cracking, spreading, and settlement of embankment material

• Failure of embankments and natural slopes

• Liquefaction (which can contribute to settlement, slope failure, spreading, and forces on structures)

• Structural distress to bridges, retaining walls, and culverts

Surface fault rupture and resulting displacement is not expected since there are no known faults along the alignments.

Under the No-Build Alternative, the existing East Span would be able to withstand a moderate earthquake. However, it is anticipated that the existing East Span would experience multiple failures at structure joints and potential collapse into the Bay in the event of a Maximum Credible Earthquake (MCE).

The Retrofit Existing Structure Alternative would provide additional support to the existing East Span compared to the No-Build Alternative. Following retrofit construction, the bridge should be able to withstand an MCE. It is anticipated that in the event of an MCE, the retrofitted East Span would experience damage to truss members in the steel superstructure. The addition of new piers E2A and E2B would eliminate a current imbalance in the existing main span, which would reduce structural damage. Although the retrofitted main span would be expected to withstand an MCE, it is likely that the main span structure, and potentially other shorter spans, would require extensive repair or replacement, possibly requiring closure of the bridge for a six-month to one-year period, depending on the extent of the damage.

The replacement alternatives would be designed to meet current seismic safety standards. It is expected that replacement alternatives would withstand an MCE on the San Andreas or Hayward faults. Seismic design criteria for all replacement alternatives are intended to ensure non-collapse and serviceability of structures when subjected to peak acceleration during a seismic event.

Potential for damage resulting from an MCE exists. The main span tower structure near YBI would be sited on shallow, sloping bedrock, requiring foundations deep into rock. Damage due to tower settlement in an MCE would most likely be minor and confined to local deflection, cracking, and misalignment of pavement on the main span. Anticipated damage could easily be repaired to permit the replacement alignment to serve a lifeline function.

There is potential for cracking, spreading, and settlement of bridge embankments throughout the project area, particularly at the Oakland Touchdown area. The damage would most likely consist of small earth slumps, differential settlement, misalignment, separation, and cracking which can be quickly repaired. The likelihood of large-scale shear failure of embankments is small.

Based on USGS map information, it appears that most of the Oakland Touchdown area, which ranges in elevation from about 0 to 3.6 meters (0 to 12 feet) would be subject to inundation from a 200-year-return-period tsunami. At lower return periods (for example, 25 to 100 years), the potential for inundation decreases substantially.

The effects of a tsunami would be flood damage, erosion, and damage caused by wave and water forces on structures. People, automobiles, and buildings could be washed away as during a flood. Tsunami warnings are a component of the regional emergency warning system and would be implemented in the case of a threat of tsunami inundation.

The structural design of the SFOBB replacement alternatives on the Oakland Touchdown area would include the capability of resisting water/wave/current-induced loading.

This section discusses potential impacts to water quality in the project area and associated mitigation measures. The water quality impacts and design considerations discussed in this section would generally be the same for all the replacement alternatives.

The No-Build Alternative would not modify current water quality conditions as current methods of operation and maintenance would continue.

The Retrofit Existing Structure Alternative may have a temporary water quality impact during construction activities. These activities may include dredging, dewatering, concrete pouring, welding, and other activities that have the potential to impact water quality (see Section 4.14.7 for discussion of construction-related impacts). Potential long-term impacts have also been evaluated, and it has been determined that there are no long-term impacts because the existing facility would not be modified in terms of its operation and drainage system. Therefore, current water quality conditions would not be altered.

All replacement alternatives have similar potential to affect water quality in San Francisco Bay, both during and after construction (see Section 4.14 for discussion of construction-related impacts).

The replacement alternatives would consist of two parallel bridge decks, each accommodating five standard travel lanes and standard shoulders. The overall width of the westbound bridge deck is proposed to be 25.07 meters (82 feet). The width of the eastbound bridge deck, which includes a 4.7-meter (15.5-foot) pedestrian/bicycle path, would be 29.72 meters (97.5 feet). The replacement alternatives would increase the surface area exposed to precipitation. A corresponding increase in the quantity of pavement storm water runoff from the East Span from a given rainfall event is expected.

Pollutants commonly found in highway storm water runoff include heavy metals, oil and grease, suspended and dissolved solids, nutrients, bacteria, and some of the hydrocarbons in the gasoline and diesel range. Pollutants less common in highway storm water runoff include volatile organics, semi-volatile organics, phenols, pesticides, polychlorinated biphenyls, and synthetic biocides, depending on the characteristics and location of the highway.

Impacts. The proposed replacement alternatives would not be expected to increase concentration levels of those pollutants commonly found in highway runoff, nor is the design expected to elevate the levels of those less common constituents. However, the mass loading of some constituents may increase relative to the increase in exposed area.

The proposed concrete structures should not require the sandblasting and painting effort currently expended in maintaining the existing SFOBB. The expected reduction in paint removal and painting efforts should provide a long-term reduction of adverse water quality impacts associated with maintenance of the existing structure. This would be considered a beneficial effect. Furthermore, an additional water quality benefit would be obtained from the new bridge design by the addition of traffic shoulders, in that the impacts caused by discharges that result from vehicle accidents and spills would be minimized by the increase in emergency response. The traffic shoulders would allow emergency vehicles, maintenance crews, and hazardous material response teams to travel freely on the shoulder to an accident location. Additionally, traffic shoulders would allow for enhanced sweeping operations on the bridge by being able to drive sweeper vehicles at slower speeds and conduct the operations without the need for lane closures and traffic obstruction. Slower sweeping operations combined with state-of-the-art sweeping equipment would more effectively pick up finer particles and associated pollutants. Eliminating or minimizing lane closures would also help traffic flows which, in turn, would minimize the deposition of pollutants related to stop-and-go traffic, such as metals from brake pad linings.

Permanent or temporary impacts to natural resources may occur in association with each project alternative. This section discusses permanent impacts, which may result in direct impacts to species or habitat that require acreage replacement. Specific mitigation measures will be developed in consultation with regulatory and permitting agencies. Conceptual mitigation measures are presented following each resource affected by a project alternative.

Temporary impacts to natural resources are identified as impacts from construction activities, such as construction noise from pile driving, or air emissions. These temporary impacts would end upon completion of construction and are addressed in Section 4.14.

The northern and southern replacement alternatives would result in temporary impacts to harbor seals, chinook salmon, steelhead, green sturgeon, and longfin smelt. Temporary impacts are associated with construction activities that would continue for approximately 51 months. Since these species would only be affected temporarily during construction activities, impacts are addressed in Section 4.14 of this report.

Both northern replacement alternatives could result in permanent impacts to marsh gumplant, double-crested cormorant, American peregrine falcon, western gulls, and shorebirds. Replacement Alternative S-4 could result in permanent impacts to the double-crested cormorant, shorebirds, western gulls, and the American peregrine falcon. The replacement alternatives would not result in impacts to the California brown pelican, saltmarsh common yellowthroat, and California clapper rail. A discussion of these species is provided below.

Marsh Gumplant/Alameda Song Sparrow. As shown in Figures 3-17 and 3-18 in Appendix A, marsh gumplant occurs in four areas within the project area. Only one location of marsh gumplant would be affected by the northern replacement alternatives. Replacement Alternative S-4 would also result in the removal of marsh gumplant, located to the south of the existing bridge on Port of Oakland property. Impacts to the marsh gumplant would not affect the long-term viability of the species; however, construction of the project would reduce the amount of marsh gumplant in the area, which is potential supporting habitat for the Alameda song sparrow.

Double-Crested Cormorant. Double-crested cormorants currently nest on the existing East Span. Construction of any replacement alternative would include the dismantling of the existing East Span bridge, which would result in removal of nesting sites for the double-crested cormorant.

Construction activities associated with a replacement alternative could also potentially cause indirect impacts to nesting cormorants due to noise and visual disturbance. These impacts are addressed in Section 4.14.

American Peregrine Falcon. An American peregrine falcon pair nests on the existing East Span. Construction of a replacement alternative would include dismantling the existing East Span structure which would result in the removal of nesting sites for the American peregrine falcon.

Construction activities associated with a replacement alternative would potentially cause indirect impacts to nesting and roosting peregrines due to noise and visual disturbance. These temporary impacts are discussed in Section 4.14. Impacts to this species would primarily be associated with construction activities that occur during the breeding season, February 1 through July 31.

Shorebird Species. Shorebirds include migratory birds which are protected under the Migratory Bird Treaty Act. The replacement alternatives would not result in a direct impact to shorebird species; however, they would result in the removal of supporting resting and feeding habitat. As discussed under Section 4.9.2, the northern replacement alternatives would result in the removal of mudflats. The removal of mudflats along the northern portion of the Oakland Touchdown area would decrease the amount of shorebird feeding habitat available and shade mudflat areas that would remain after construction is complete. This impact would occur in association with Replacement Alternatives N-2 and N-6 only.

The S-4 replacement alternative would result in the removal of shorebird upland refugia, which provides valuable resting habitat during high tides. Upland refugia occurs on the south side of the Oakland Touchdown area and is known to support roosting shorebirds during wintering months.

Western Gull. Potential direct impacts to the western gull would occur if nests are present on pier footings of the existing East Span SFOBB prior to the dismantling of the structure.

Saltmarsh Common Yellowthroat/California Clapper Rail. Direct impacts to the saltmarsh common yellowthroat and California clapper rail are not anticipated since they occur at the Emeryville Crescent, which is located outside of the project area. Indirect impacts, including noise, would not occur since construction activities would not result in an increase in noise levels at the Emeryville Crescent area.

California Brown Pelican. Direct impact to the California brown pelican would not occur since this species does not nest in the project area. Indirect impacts to the California brown pelican are not anticipated since the proposed construction activities would discourage pelicans from resting or foraging near the existing bridge.

Pacific Herring. The northern and southern replacement alternatives would result in temporary impacts to Pacific herring. Temporary impacts are addressed in Section 4.14.8 of this report.

Patches of natural communities such as coast live oak woodland, northern coastal scrub, and northern coastal saltmarsh occur within the project area. Impacts would only occur to the coast live oak woodland in association with the replacement alternatives.

Coast Live Oak Woodland. Three patches of coast live oak woodland occur on slopes of the YBI. Portions of two of these areas could be removed by the alteration of Macalla Road, which is required for all of the replacement alternatives using the North Detour Option. Macalla Road would be realigned at a lower grade in an area located within the dripline of the tree overstory. This activity would damage the root zone of trees and result in a loss of six coast live oak trees. The coast live oak trees that would be affected range in diameter-base-height (dbh) from 45 to 127 centimeters (18 to 50 inches).

Consultation will be initiated with the USFWS regarding the American pegrine falcon, which is protected under Section 7 of the Endangered Species Act, and species protected under the Migratory Bird Treaty Act, including the California brown pelican, western sandpiper, and black-bellied plover. Coordination will be initiated with the NMFS concerning the potential for impacts to fish species protected under the Endangered Species Act, including the chinook salmon and steelhead, and marine mammals protected under the Marine Mammal Protection Act. In addition, consultation regarding potential impacts to Pacific herring and species regulated under the California Endangered Species Act, including the double-crested cormorant, will occur with the CDFG.

Resource agencies will review and comment on this Draft EIS and supporting technical studies. A mitigation and monitoring plan for the selected preferred alternative would be developed and provided for comment. The Final EIS will report the results of consultations under the federal and state Endangered Species Acts. Agency concurrence in the impact assessment and mitigation concepts will be obtained prior to federal approval of the Final EIS.

The effects of the Retrofit Existing Structure Alternative are temporary in nature due to construction activities. These effects and their mitigation are discussed in Section 4.14.8.

Wetlands. Replacement Alternatives N-2 and N-6 would result in the loss of 0.03 hectare (0.07 acre) of non-tidal wetland located on the south side of the Oakland Touchdown. The S-4 Replacement Alternative would result in the total loss of 0.04 hectare (0.10 acre) of two non-tidal wetland areas on the south side of the Oakland Touchdown. Loss of jurisdictional wetlands will be mitigated at a mitigation ratio of 3:1 by the creation of new wetland habitat or enhancement of existing wetlands within the project area. The mitigation ratio is a function of the habitat value of land that would be affected relative to the land to be acquired. This approach is based on habitat evaluations conducted for similar projects within the Bay Area.

Potential mitigation sites located in the project area include the Oakland outer harbor, located on the south side of the Oakland Touchdown, and the Emeryville Crescent. The impacts to non-tidal wetlands will occur to wetlands located on the Oakland outer harbor. Mitigation of project impacts could be accomplished by purchasing some property in the Oakland outer harbor or the Emeryville Crescent for creation of shallow non-tidal wetlands and preservation. Lands acquired for mitigation would be created or enhanced to provide a no-net loss of in-kind wetland habitat value and acreage. A conceptual mitigation plan will be developed in consultation with the California Department of Fish and Game, U.S. Fish and Wildlife Service, National Marine Fisheries Service, Army Corps of Engineers, and the U.S. Environmental Protection Agency following the identification of the preferred alternative for the project. This conceptual plan will be discussed in the Final EIS and will address the following issues:

• Goals,
• Site options,
• Implementation plan,
• Success criteria, and
• Maintenance and monitoring.

During final project design and the project permit process, the conceptual mitigation plan will be further refined into the final detailed project mitigation and monitoring plan.

Eelgrass. Both of the northern replacement alternatives would result in the loss of 0.75 hectare (1.8 acre) of eelgrass beds located on the north shore of the Oakland Touchdown and YBI. Of this amount, about 0.50 hectare (1.2 acres) would be affected by placement of work barges. The southern replacement alternative would result in the loss of 0.30 hectare (0.75 acre) of eelgrass located along the southern shore of YBI. Mitigation for impacts to eelgrass beds will include transplanting the eelgrass to be removed to adjacent shallow areas to in-fill existing stands, currently containing scattered patches of eelgrass. Creation of eelgrass beds is considered experimental, and appropriate pre-creation studies, post-project monitoring, and contingency measures will be developed and implemented to ensure successful creation of eelgrass beds as proposed. Successful transplanting of eelgrass beds are dependent on the following variables: 1) balance of sedimentation and scour, 2) transplantation protocol for eelgrass, 3) compression and settling of the sediment fill and underlying material, and 4) contamination. Due to the experimental nature of successfully transplanting eelgrass beds a 3:1 replacement ratio will be implemented. As discussed for the wetland mitigation, a conceptual mitigation plan will be addressed in the Final EIS.

Mudflats. Replacement Alternatives N-2 and N-6 would result in the removal of 0.12 hectare (0.3 acre) of mudflats on the north side of the Oakland Touchdown. The southern replacement alternative would result in the loss of 0.06 hectare (0.15 acre) of mudflats located along the south side of YBI. Potential mitigation sites would include the Oakland middle harbor that provides opportunities to restore intertidal mudflat habitat. As discussed for the wetland mitigation, a conceptual mitigation plan will be developed for the replacement of mudflats at a ratio of 3:1 and will be included in the Final EIS.

American Peregrine Falcon. The removal of the existing bridge would result in the loss of nesting area for the peregrine falcon. Mitigation, summarized below, will be similar to that outlined in the contract between Caltrans and the Santa Cruz Predatory Bird Research Group (SCPBRG) for the interim seismic retrofit project.

Mitigation for the East Span peregrine pair will consist of a monitoring and release program conducted during each year of bridge construction and during the dismantling of the existing bridge. Any chicks present on the existing bridge will be removed and released at a natural site in either Point Reyes, the Channel Islands or the Sierra Nevada mountains. These activities will be conducted by the SCPBRG.

If dismantling of the existing bridge occurs during the nesting season, off-site release efforts will be conducted by the SCPBRG. If dismantling of the bridge occurs during

the non-breeding season, a monitor from the SCPBRG will ensure that adults and juveniles are not present on the bridge during the period of dismantling.

Peregrines would likely nest on the new bridge once construction activities associated with the project are complete. Therefore, no nest structures would be created on the new bridge for peregrines. If peregrines do recolonize the new bridge, monitoring and off-site release efforts by the SCPBRG will continue as they have for the existing bridge, if necessary to avoid potential maintenance activity impacts.

Double-crested Cormorant. Mitigation for permanent loss of habitat is currently being investigated and will include on-site or off-site mitigation or a combination of both as outlined below:

In order to mitigate for the permanent loss of nesting habitat for this species due to the dismantling of the existing bridge, nest ledges could be constructed on piers of the new bridge. Double-crested cormorants could be attracted to the platforms using decoys and social attraction methods. Maintenance of platforms would not be required; however, platforms should be replaced as necessary. The creation of nest structures along the new bridge would prevent conflicts with future maintenance activities that would likely occur along other areas of the new structure.

Consultation between the bridge architects and the resource agencies will be required before a final design for the platforms can be made. Aspects under consideration for the platforms include the following:

• Each platform should hold five to six nests.

• Four to five platforms would be placed on one bridge pile; approximately 100 platforms could be provided.

• Platforms should be at least 73 meters (240 feet) above the surface of the water.

• Decoys would be used to attract birds to the platforms once construction activities on the new bridge are complete.

• Platforms would be replaced as necessary.

Off-site Mitigation.

Option 1. Off-site enhancement of nesting habitat for this species could be another mitigation option as an alternative to, or in additon to, on-bridge nesting sites. One off-site mitigation option would be to establish nesting habitat for double-crested cormorants at CDFG-managed land near Vallejo. Restoration of several salt ponds in that area will cause the removal of artificial structures used by double-crested cormorants as nesting and roosting sites. Since cormorants are already breeding in these salt ponds, the creation of new platforms in the ponds would have a high chance of attracting cormorants. New artificial structures such as wharves could be floated in the salt ponds and anchored before existing structures are removed.

Option 2. A second option relates to a settlement that will soon be reached over a recent oil spill into the San Francisco dry docks from a Federal Department of Transportation vessel. Several double-crested cormorants were impacted by the spill. Through coordination with CDFG staff, it has been suggested to create a partnership between Caltrans and the CDFG or USFWS to enhance natural habitat in the Bay for double-crested cormorants as wells as other seabird species.

Under this proposal, funds from the oil spill settlement and project mitigation funds could be used to purchase Red Rock Island (located south of the Richmond-San Rafael Bridge) to enhance the habitat to encourage double-crested cormorant nesting. Enhancement of the area may include a social attraction project where decoys and taped recordings of double-crested cormorant calls are played in order to attract this species to nest at the site. Red Rock Island would be managed by either the CDFG or the USFWS. A similar social attraction project is being conducted for common murres at Devil’s Slide along Route 1, in San Mateo County, and has been very successful. However, double-crested cormorants are not known to have nested on Red Rock Island in the past. Thus, this proposal would be highly experimental.

The above on-site and off-site options will be coordinated with the resource agencies and the resulting mitigation measures for the double-crested cormorant will be included in the conceptual mitigation plan and discussed in the final EIS.

Shorebird Species. Shorebirds are protected under the Migratory Bird Treaty Act and would be affected by all replacement alternatives that would result in the removal of mudflats and upland refugia. The northern and southern replacement alternatives would remove mudflats that currently provide feeding habitat for shorebirds. Removal of 0.12 hectare (0.3 acre) of mudflats associated with the northern alternatives and 0.06 hectare (0.15 acre) associated with the southern alternative is not anticipated to adversely affect shorebirds. The realignment of the Caltrans maintenance road, associated with the northern replacement alternative, would remove the upland habitat currently used by the shorebirds for roosting during high tide. The southern replacement alternative would result in the removal of upland refugia. The decline in the amount of upland habitat located adjacent to mudflats throughout the Central Bay has reduced the areas available to shorebirds for roosting, during high tides.

Mitigation for the removal of upland refugia would include preservation of upland areas as part of the new park envisioned for the southern portion of the Oakland Touchdown area. The park would be in areas formerly within the Caltrans right-of-way, as well as on land within the Oakland Army Base. The park would provide public access to the Bay and would include an excluded area of upland refugia for the shorebirds. The design for the park would include an upland refugia area fenced off from public access to prevent human or animal disturbance to the shorebirds. In addition, signs would be posted to educate visitors about shorebird ecology and the need to preserve and create shorebird habitat around the San Francisco Bay.

Coast Live Oak Woodland. The replacement alternatives with the north detour option require construction on Macalla Road which could result in removal or disturbance to the root zone and potential loss of six trees. Post-construction surveys would be conducted to determine the number of trees actually removed or affected. Oaks would be replaced in accordance with the CCSF tree ordinance. A conceptual mitigation plan, specifying goals, replacement ratio, success criteria, and monitoring will be determined in coordination with the San Francisco Public Works Department that has authority under the CCSF tree ordinance. The conceptual plan will be summarized in the Final EIS.

This section reports the potential for East Span project alternatives to affect archaeological and historic resources. Mitigation measures discussed in this section are conceptual and subject to SHPO and ACHP review. Views on mitigation measures will also be solicited from interested parties such as Native Americans, preservation organizations, and public agencies, e.g. the City of Oakland, the U.S. Navy, and the City and County of San Francisco.

Section 106 of the National Historic Preservation Act requires agencies to take into account the effects of their projects on historic properties eligible or listed on the National Register of Historic Places. Impacts to resources are assessed by application of the Criteria of Effect and Adverse Effect (36 CFR Part 800.9). An undertaking is considered to have an adverse effect on a historic property when the undertaking may diminish the integrity of the property’s location, design, setting, materials, workmanship, feeling, or association. Pursuant to 36 CFR 800.9, an adverse effect on a historic property includes, but is not limited to: (1) physical destruction, damage, or alteration of all or part of the property; (2) isolation of the property from or alteration of the character of the property’s setting when that character contributes to the property’s eligibility; (3) introduction of visual, audible, or atmospheric elements that are out of character with the property or alter its setting; (4) neglect of a property resulting in its deterioration or destruction; and (5) transfer, lease, or sale of the property. SHPO views on project effects are in a letter dated September 10, 1998, located in Appendix G.

In applying the Criteria of Effect and Adverse Effect, it appears that six of the ten proposed combinations of replacement alternatives and detour options will have an adverse effect on CA-SFr-04/H; the remaining three (No-Build, N-2 North-South Detour, and N2) will have no effect (see Table 4.10-1).

In many cases, the effects of an undertaking that would be considered adverse may be considered not adverse if appropriate data recovery is carried out. However, if Native American burials may be present in an archaeological site that would be affected by an undertaking, project effects would be considered adverse. Because the potential exists for the prehistoric component of CA-SFr-04/H to contain additional burials, the replacement alternatives and detour options that will physically affect the site have been determined to cause an adverse effect.

When an alternative has been identified, and if that preferred alternative and or detours will adversely affect CA-SFr-04/H, Caltrans will include in a Memorandum of Agreement a commitment to prepare an archaeological research design and treatment plan for pre-construction archaeological data recovery. It will be submitted to the SHPO for approval and to the U.S. Navy for comment pursuant to a previously executed Archaeological Resources Protection Act permit and pursuant to the National Historic Preservation Act. The treatment plan will be made available to

Source: Woodward Clyde, San Francisco-Oakland Bay Bridge East Span Seismic Safety Project Finding of Effect for Archaeological Resources Located in the City and County of San Francisco and the City of Oakland, Alameda County, California, July 1998.

interested Native Americans who are on a list provided by the Native American Heritage Commission. Continued effort will be made to contact interested Native Americans to elicit comments on any cultural concerns.

Monitoring by a Native American will be conducted during all archaeological field investigations. If human remains are located, either Native American or non-Native American, Caltrans will ensure that treatment of the remains will comply with all applicable state and federal laws and regulations, including the Native American Graves Protection and Repatriation Act of 1990 (P.L. 101-601, 25 U.S.C. 3001-3013). California Public Resources Code Sections 5097.98 and 5097.99 require protection of Native American remains which might be discovered and outline procedures for handling any burials found.

In all cases where human remains are discovered, the County Coroner will be notified and, in the case of Native American remains, the state Native American Heritage Commission (NAHC) will be notified. Consultation with a Most Likely Descendant designated by the NAHC will be made as to the extent of respectful treatment and the location for re-interment.

If human remains are discovered during construction, all work will cease in the immediate vicinity of the discovery until the appropriate treatment has been completed.

Mitigation. Consultation will continue with FHWA, SHPO, and Advisory Council on Historic Preservation (ACHP) concerning elibigility and potential for impacts to CS-SFR-04/H. An archaeological research design and treatment plan will be prepared for pre-construction archaeological investigations by Caltrans and submitted to the SHPO for concurrence.

Native American monitoring will be requested at all archaeological field investigations.

If any buried cultural materials are encountered during construction, work will cease in the vicinity of the discovery, and a Caltrans archaeologist will be contacted to evaluate the finds.

The No-Build Alternative would have No Effect on any of the historic architectural resources within the project APE.

The Retrofit Existing Structure Alternative would modify the existing SFOBB East Span and change views to the Bay from Quarters 1. These changes would result in an Adverse Effect. Potential effects are summarized below.

San Francisco-Oakland Bay Bridge (SFOBB). The Retrofit Existing Structure Alternative would add new piles and pile caps at many piers, construct two new piers at the main span of the cantilever truss and encase several steel piers in concrete. These changes to the existing structure would substantially alter the East Span portion of this historic structure, resulting in a loss of integrity of design and materials. Therefore, the Retrofit Existing Structure Alternative would have an Adverse Effect on the SFOBB.

Caltrans Garage (YBI). This structure would be retained under the retrofit alternative. The Retrofit Existing Structure would have No Effect on this resource.

NE – No Effect; NAE – No Adverse Effect; AE – Adverse Effect

Source: Caltrans, SFOBB East Span Seismic Safety Project Finding of Effect Report, July 1998; Parsons Brinckerhoff, September 1998.

Caltrans Electrical Substation (YBI). The Caltrans Electrical Substation at the Oakland Touchdown would be retained. No Effect to this resource would result from implementation of the Retrofit Existing Structure Alternative.

Caltrans Electrical Substation (Oakland Touchdown Area). This structure would be retained under the retrofit alternative. No Effect would result from the project to this building.

Key Pier Substation. No Effect to the Key Pier Substation would result from the Retrofit Existing Structure Alternative.

Senior Officers’ Quarters Historic District (includes Quarters 1 to 7 and Buildings 83, 205, and 230). The retrofit of piers YB2 through YB4 on YBI would result in encasement of the existing steel piers in concrete. The resulting walls would substantially impair the view from Quarters 1 across the eastern portion of San Francisco Bay. This would constitute a visual intrusion that would diminish an important aspect of the building’s setting, and result in an Adverse Effect.

Quarters 1. Retrofit of piers YB2 through YB4 on YBI, as described above, would result in an Adverse Effect to Quarters 1.

Quarters 8. No work related to the retrofit alternative would cause impacts to Quarters 8. This residence is located downslope from the existing structure within the USCG base. Bay views from the structure would not be modified by retrofit activities. The retrofit alternative would have No Effect on the historic attributes of Quarters 8.

Quarters 9. No work related to the retrofit alternative would result in impacts to Quarters 9. This structure is located on Treasure Island Road facing southeast. Views from the structure to the Bay would not be affected and access to the building would not be modified. The retrofit alternative would have No Effect on the historic attributes of Quarters 9.

Quarters 10. No Effect would result to Quarters 10 from the Retrofit Existing Structure Alternative. This residence is located at an elevation equal to the bridge decks and is screened from view of the bridge by surrounding Oak woodland vegetation. No work related to the retrofit alternative would have an impact on Quarters 10.

Building 267. This building is a garage adjacent to Quarters 10 and is screened from view of the SFOBB by surrounding vegetation. No Effect to this building would result from the retrofit alternative.

Building 262. The retrofit alternative would have No Effect on Building 262. Work to strengthen existing piers on YBI and immediately offshore would not have an effect on the materials or craftsmanship, which make the building significant or diminish the understanding of the relationship of the building to early military occupation on YBI.

The retrofitted structure would cause no permanent change in the noise levels from existing conditions.

Alignment alternatives would affect historic architectural resources on YBI and at the Oakland Touchdown in addition to the SFOBB.

Noise does not directly affect historic buildings, but an increase in noise may change the character of a property, diminishing its integrity of setting and feeling. However, none of the new bridge alternatives being considered for this undertaking would result in noise increases at or near the historic buildings. Existing noise levels were measured at six locations within the Officers’ Quarters Historic District, as well as in the vicinity of Quarters 8, 9, 10, and Building 262. At all of these locations, the expected noise levels after completion of the new bridge are equal to or lower than the existing noise levels. Noise levels are expected to decrease by six to ten dBA within the historic district. The expected decrease in noise is a result of two factors: (1) the new concrete structures will eliminate radiation of sound through the bridge decks and reduce noise created by vehicles traveling over the expansion joints; and (2) the side-by-side configuration of the new roadways will eliminate the existing condition of traffic noise generated at the lower deck being reflected from the underside of the upper deck.

San Francisco-Oakland Bay Bridge (SFOBB). All of the replacement alternatives would require demolition of the existing East Span. Demolition of this historic structure would constitute an Adverse Effect.

Caltrans Garage (YBI). This contributing structure to the SFOBB would be removed under a