4.14 TEMPORARY EFFECTS DURING CONSTRUCTION ACTIVITIES
This section describes potential temporary impacts of project alternatives that may occur during project construction. Because the No-Build Alternative would not involve any project-related construction, discussions are focused on the build alternatives including the Retrofit Existing Structure and Replacement Alternatives N-2, N-6, and S-4. In general, the potential for disruptive construction effects would correspond to the type and location of activities proposed in each construction stage, and the duration of the overall construction process associated with each alternative.
The Retrofit Existing Structure Alternative is estimated to require about 48 months to construct. For the replacement alternatives, the estimated total number of months required for bridge completion is 51 months, which includes construction of the over- water sections (main span and skyway), and construction of the detour structures on YBI. It is estimated that the entire project will be completed in 57 months, which includes dismantling the existing East Span.
4.14.1 Community Impacts
Potential construction period impacts to residents, government facilities at YBI, and businesses at the Oakland Touchdown area are addressed in the following section.
Neighborhoods and Businesses
During construction, motorists and pedestrians on YBI and the Oakland Touchdown area would experience some delays and detouring. Some streets would be closed during construction and others would be subject to periodic lane closures (See Section 4.14.2, Transportation Effects During Construction). Further delays would occur as construction trucks and equipment use local streets.
Construction-period Safety and Security
Safety and security issues associated with the construction of the East Span Project include potential disruption of traffic movements, including potential for obstruction of access to YBI and Oakland Touchdown governmental structures and Quarters 1-10 on YBI by emergency and law enforcement vehicles. Heavy vehicle movements, possible hazardous wastes excavation and transport, and construction site activity would also create potential safety concerns.
Economic activity generated by the proposed build alternatives is anticipated to benefit the Bay Area region and would also follow the labor and material markets for highway bridge construction. Refer to Section 3.1 for a complete discussion of employment-generation effects of the project.
Best construction management practices would be in place to ensure the safety of construction workers, local employees, and residents during construction of the build alternatives. Fencing and lighting of construction and staging areas, recognized safety practices for the utilization of heavy equipment, and the movement of construction materials would be implemented to avoid accidents. During construction, Caltrans would require that the project contractor be responsible for job-site safety and security. Detours, lane blockages, and truck entrance locations would be well signed.
The contractor would apprise police, fire, and other emergency response agencies of construction activities, detours, and road blockages throughout the construction process.
Safety and Security
The public would be alerted about detours, lane blockages, and truck entrances. These locations would be well signed.
4.14.2 Transportation Effects During Construction
Construction activities proposed under all build alternatives would temporarily affect transportation facilities within the project area, as described below.
Construction activities under all build alternatives would result in some traffic disruption on I-80 and temporary bridge closures during off-peak travel times. Construction could also affect local streets on YBI and the Oakland Touchdown area. In addition to temporary traffic disruptions (closures and detours), construction traffic would be noticeable on area roadways and could contribute to localized congestion from time to time.
During the final stage of construction of replacement alternatives, the detour structures on YBI would be connected to the YBI Tunnel portal. This construction would require closure of traffic lanes on the SFOBB during off-peak travel times. During these closures, traffic would be directed to use either the Hayward-San Mateo or Richmond-San Rafael bridges.
In general, construction of the Retrofit Existing Structure Alternative would result in greater and more frequent disruptions to mainline freeway traffic, compared to the replacement alternatives, because construction would occur while the bridge is open to traffic. The replacement alternatives would, however, have greater traffic impacts to local streets and potentially create more delays as "rubbernecking" drivers on the existing SFOBB watch ongoing construction on the neighboring replacement spans. This can be mitigated somewhat by using some type of temporary visual barrier. More specifics regarding construction-period traffic effects are presented below.
Yerba Buena Island. Under the Retrofit Existing Structure Alternative, off-peak lane closures would be necessary during the construction period. In addition, the East Span would need to be closed while the new piers are connected to the cantilever section. Construction activity would be scheduled to conform to the lane closure charts.
Replacement alternatives could require the closure of the eastbound right-hand off-ramp and the westbound right-hand on-ramp on the east side of the island for a period of 18 months during construction. Access to the SFOBB would continue by the remaining eastbound left-hand off-ramp onto Treasure Island Road and the right-hand westbound on-ramp from Treasure Island Road.
For all three of the replacement alternatives, construction of bridge pier foundations on YBI would affect a portion of Macalla Road, the undercrossing connecting Treasure Island Road with Macalla Road, and the entrance to the USCG Station.
Depending on the detour alignment selected, the foundations and piers for the temporary detour structures could block the undercrossing connecting Macalla Road and Treasure Island Road, as well as Macalla Road and the entrance to the USCG Station.
Construction of the Retrofit Existing Structure and replacement alternatives would increase traffic volumes on YBI by introducing construction-related traffic. Slow-moving heavy trucks would operate on Macalla Road, creating delays for other traffic. This impact would be most severe for the first two years of construction when the labor force is the largest.
Construction of the replacement alternatives would take place on the eastern side of YBI, the parade grounds, and the flat area beneath the existing SFOBB might be used by a contractor as a construction staging area. Unloading and stockpiling of construction equipment and bridge components are likely uses.
Under the replacement alternatives, dismantling of the existing East Span would include removal of portions of the upper deck using the existing bridge. Some materials would be removed by truck from YBI, increasing traffic on local streets. Heavy trucks on Macalla Road may conflict with other vehicles due to the narrow width and steep grades of the roadway. Truck traffic on Macalla Road would be regulated by flaggers to ensure that there are no conflicts between oversized vehicles using the road. Heavy construction vehicles would also likely cause damage to the pavement on Macalla Road. Under all the proposed alternatives, local streets would be repaired following construction.
Because additional traffic using YBI during construction may exceed the capacity of the freeway ramps, Caltrans would require that contractors limit the number of vehicles on the island. Construction worker access using private cars would be limited, and travel on the island restricted to essential vehicles. Contractors would be required to provide alternate means of transportation for workers.
The former parade grounds located east of Quarters 1 may be used for construction staging, resulting in the temporary loss of 315 informal parking spaces. The temporary loss of parking in this lot may affect the accessibility or use of existing facilities on the island, including the Nimitz House. Large-scale special events may experience parking shortages. On-street parking adjacent to Quarters 1-7 would remain open during construction.
Temporary restriction of access to Building 267, the garage at Quarters 10, would be required under the north replacement alternatives, north-north temporary detour structures option. Vehicular access blockage to the garage would result from the construction period lowering of the grade of Macalla Road adjacent to Quarters 10. As necessary, the project design would include temporary replacement parking and a temporary walkway from the parking area to Quarters 10. The replacement parking would be located as close to Quarters 10 as feasible, such as near Building 240.
Oakland Touchdown Area.. Alignment Alternatives N-2 and N-6 would require closing the access road on the north side of I-80 during construction, eliminating vehicle access to the shoreline west of Radio Point Beach. Alternative S-4 would displace a portion of Burma Road from about the location of the billboard west to the end of the Oakland Touchdown area. The road is not required for access to any of the buildings in this area. Closure and relocation of Burma Road would not affect traffic circulation.
Higher volumes of heavy vehicle traffic anticipated during construction of the Retrofit Existing Structure Alternative and the replacement alternatives may slightly affect traffic and transit operations. The increased number of trucks on Maritime Street, for example, could potentially cause minor delays to traffic and to AC Transit Transbay Route A and Local Route 13. The delay would be roughly equivalent to a missed signal cycle and would be within the range of normal traffic conditions, particularly during peak commute hours. No mitigation is recommended for this minor potential delay.
Under the Retrofit Existing Structure Alternative, retrofit work in shallow water west from the Oakland Touchdown area would be completed from construction trestles. A temporary trestle would be constructed on either side of the existing bridge, with cross-trestles at each pier to provide construction access around the piers. Work would be done from barges where water depths can accommodate standard draft barges (waters depths of 3.66 meters [12 feet] or greater). Construction activity around the existing piers and for the new piers would also require barges to support large-scale construction equipment. The navigation channel would be constricted at times while the barges are in place to retrofit Pier E2 and construct new piers E2A and E2B. The two new piers would ultimately narrow the navigation channel in accordance with USCG regulations.
Under the replacement alternatives, the nature, duration, and location of marine construction activities would continually vary due to in-water activities associated with construction of the main span and skyway and dismantling the existing East Span. The presence of barges, other construction vessels, and temporary falsework would restrict the navigation channel. Additionally, temporary closures of portions of the navigational channel could occur during critical construction points due to overhead hazards.
USCG Station Access To maintain access to the USCG Station, Caltrans would require that the contractor construct a detour around the pier foundations to keep Macalla Road open at all times. This detour would be steeper than the existing road and would require removal of some trees adjacent to the garage (Building 267) at an existing residential unit (Building 10). Construction of the detour may require a cut into the uphill slope.
Caltrans would require the contractor to stage the construction of the pier foundations blocking access to the USCG Station so that one of the three possible entrances to the station would be open at all times. Piers would be constructed in a sequence to ensure that access to the USCG station is maintained without interruption.
Foundations and piers for the temporary detours would be constructed to avoid the surface roadways, where feasible.
Following construction, steps would be taken to restore areas affected by construction of detours and temporary access to the USCG facility. Macalla Road would be restored to its original grade to the extent feasible, trees would be replanted, slopes would be re-graded to approximate natural contours.
Construction Vehicle Traffic
Motor vehicle detours would be constructed and flaggers employed to ensure motorist safety in the construction zone. Wide and oversized loads would be restricted to barges, where possible.
Caltrans would establish a maximum number of workers driving and parking on the island based on the capacity of the existing SFOBB ramps, space needed for construction staging, and concerns of the Navy and USCG. In general, parking would be restricted to essential vehicles.
Caltrans would consult with the USCG to implement a vessel warning system when construction vessels are placed in the water within the bridge construction zone. Caltrans would obtain a permit to modify the existing bridge or construct a replacement bridge from the USCG pursuant to Section 9 of the Rivers and Harbors Act. Notification to mariners and other requirements would be specified in the bridge permit.
4.14.3 Construction-period Visual Changes
All construction activities, whether for seismic strengthening proposed under the Retrofit Existing Structure Alternative or for the replacement alternatives, would involve the use of barges, heavy equipment, stockpiles of soils and materials, and other visual signs of construction. While noticeable to residents on YBI and others in the vicinity, these short-term visual changes would not substantially alter the character of the Bay or the communities on either side. These short-term visual changes do not include the long-term impacts of the clearing and grubbing operations. Approximately 370 trees on the eastern part of YBI will have to be removed to provide staging areas and clearances for heavy equipment. This visual impact will be mitigated as discussed in Section 4.3.4.
Residents of the bachelors enlisted quarters and the USCG officers housing as well as users of YBI would experience the most noticeable visual changes during the construction period. Flat areas on YBI are expected to be used as a construction staging area. Activities at this location may block Bay views from Quarters 1-7. Retrofit of existing piers on YBI under the Retrofit Existing Structure Alternative could require temporary structures, such as scaffolding, that would interfere with existing views. New piers constructed under the replacement alternatives would add similar temporary structures.
Replacement Alternatives would require the placement of temporary detour structures on YBI (see temporary detour drawings in Appendix A). These structures would be in place for approximately 20 months. Columns, approximately 2 meters (6.5 feet) in diameter, would be constructed to support these detour structures. The number of columns to be placed on YBI would range from 59 for the S-4 North-South detour structures to 91 columns for the N-2 North Only detour option. The S-4 Replacement Alternative would place from 35 to 60 temporary support columns on YBI. (See temporary detour drawings in Appendix A). Placement of the temporary columns would likely restrict views from YBI and would be visible from close- and moderate-range views to the east side of YBI.
Each of these detour options would result in different impacts to the local vegetation and, consequently, the appearance of YBI. See Section 4.3.4 for a more detailed description of the effects of each alignment.
Nighttime construction activities would involve the use of lighting equipment, which could cause glare, potentially affecting residents in the immediate vicinity. To reduce glare from lighting used during nighttime construction activities, Caltrans would require project contractors to direct lighting onto the immediate area under construction only and to avoid shining lights towards residences and on water and marine traffic.
For replacement alternatives, temporary detour structures would remain in place for the shortest duration possible. Dismantling of the temporary structures would take place as soon as possible after opening the new bridge to traffic. These design considerations will reduce visual impacts to the minimum possible; no mitigation is recommended.
4.14.4 Construction-period Air Quality
During some stages of project construction, the Retrofit Existing Structure Alternative and the replacement alternatives would contribute to area emissions of air pollutants. The largest sources of anticipated pollutants would be dust generated by excavation, grading, and other ground-disturbing activities on YBI and the Oakland Touchdown and exhaust emissions from equipment and marine vessels. All construction-related emissions would be temporary and vary from day to day, depending on the type of work being done. Construction-related emissions would also be experienced at different locations during the construction process, depending on the area(s) under construction at any one time and the distance to likely receptors. Because of the changing nature of these conditions (i.e., construction activity, construction location, and distance to receptors), an estimate of "total" construction emissions is not possible.
Best management practices (BMPs), as specified in Caltrans Standard Specifications (e.g., watering exposed soil surfaces, covering trucks transporting dust-producing material leaving or entering a construction site, reducing construction vehicle travel speeds on unpaved surfaces, and maintaining equipment per manufacturers specifications), would effectively reduce emissions during construction. Caltrans will require the project contractor to conform with all air pollution rules, regulations, ordinances, and statutes. Based on the requirement that these BMPs be included in all contract specifications, no mitigation is proposed.
4.14.5 Construction-period Noise and Vibration
The Retrofit Existing Structure and replacement alternatives would result in intermittent and varying levels of construction noise. Average noise levels associated with various construction phases where all pertinent equipment is present and operating at a reference distance of 15 meters (50 feet) are:
|Ground Clearing||84±6 dBA|
|Erection of Structures||85±5 dBA|
|Finishing (i.e., Paving)||89±6 dBA|
(Ref: Bolt, et. al. for the Environmental Protection Agency, 1971)
Most construction activity related to this project would be associated with the last four categories (which are the noisiest operations). Because of vehicle technology improvements and more strict noise regulations enacted during the last 26 years, this analysis will use the minimum noise level shown above. This information indicates that the overall noise level generated on a construction site could reach a noise 83 dBA at a distance of 15 meters (50 feet). Noise levels generated by construction equipment (or by any "point source") decrease at a rate of approximately six decibels (dB) per doubling of distance away from the source. For instance, at a distance of 60 meters (200 feet) from a noise source, the noise levels would be about 12 dB lower than at the 15-meter (50-foot) reference distance. At Quarters 8, the nearest residence (approximately 50 meters [164 feet] away from the construction area), the noise level resulting from typical construction activities would be approximately 73 dBA Leq. This is one dB higher than existing peak-noise-hour traffic noise on the existing East Span at this location and one dBA is not a perceptible change. Therefore, the noise from construction activity, although short-term in nature, would be only slightly higher than measured and modeled ambient daytime noise levels at this location. At a distance of 100 meters (328 feet), the noise from regular construction activities would be approximately 67 dBA Leq; at 200 meters (656 feet), construction noise levels would be approximately 61 dBA Leq; while at 400 meters (1,312 feet), the noise levels would be approximately 55 dBA Leq, or well below ambient traffic noise levels. Except for construction equipment and material staging areas, construction activities and associated noise would move along the project route as construction proceeded, and thus these levels would vary and be intermittent.
Pile driving during construction would generate noise that is unique in terms of noise level, audible characteristics, and time pattern. The higher levels of pile driver noise, which are maximum levels (Lmax) of approximately 105 dBA at a distance of 15 meters (50 feet), consist of very-short-duration impact sounds (a "bang" or "clang" noise) concentrated during a 10- to 30-minute period while an individual pile is being driven. These impact sounds attenuate with distance such that the maximum levels will be 94 dBA at 50 meters (164 feet) (i.e., the nearest residence).
Construction noise is unavoidable and could adversely affect some nearby USCG residents during construction activity periods. However, the impact would be temporary and limited to the time of the construction in any one location (except near the staging areas as noted above).
Traffic Noise During Construction
To allow for continued utilization of the SFOBB during construction, temporary detour structures would be constructed at YBI and at the Oakland Touchdown area. It is anticipated that these temporary detour structures would be in use for approximately one year. These temporary detour structures vary in design and configuration depending upon the alternative.
Based upon the results of the noise modeling for the replacement alternatives (N-2, N-6 and S-4), any one temporary detour alignment is not expected to cause an audible (generally, three decibels or greater) change in noise levels compared with another detour alignment. Modeled noise levels at a given receptor generally vary by one decibel or less when comparing the N-2, N-6, and S-4 alignments and would generally not be perceptible.
Although noise levels would be relatively similar, a south detour alignment would affect 60 USCG residential units approximately 60 meters (197 feet) from the temporary structure, while a north detour alignment would affect seven residential units (Quarters 1-7) located approximately 150 meters (492 feet) from the temporary structure.
Construction Period Noise
All construction equipment would be required to conform to the provisions in Section 7-1.01I of the latest edition of Standard Specifications to minimize noise from construction activities, such as maintaining equipment mufflers in proper operating order. The contractor will be required to comply with local noise control ordinances, to the extent practicable.
Caltrans would require contractors to install and use sound-attenuating fabric shrouds around the hammer/pile impact area of pile driver equipment during pile driving to the extent possible. Over-water construction sites may not be suitable for this technique. Where practicable, pile holes would be pre-drilled to reduce effects of pile driving.
Normal project construction activities would not generate significant levels of vibration. Pile driving, if required during the construction phase of the project, could produce ground-borne vibration levels that might be perceptible within approximately 200 meters (656 feet) of the pile-driving activity. Ground-borne vibration levels at distances of approximately 60 meters or more will not result in adverse effects. Pile driving very close to structures, within 18 meters (60 feet), can cause structural damage due to displacement of soil and resulting lateral movement. Vibration from pile driving occurring within 33 meters (110 feet) can cause architectural and structural damage to some buildings, especially unreinforced or older buildings such as Building 262.
The Retrofit Existing Structure Alternative would not require pile driving near buildings on YBI or at the Oakland Touchdown. No impacts would occur and no abatement is proposed.
Replacement Alternatives may require pile driving. Potential for impacts to structures on YBI and at the Oakland Touchdown area is discussed below.
Replacement Alternative N-2. Pile driving may be required to construct the easternmost pier on YBI. Should this construction method be employed, pile driving would occur within approximately 25-30 meters (82-100 feet) from Building 262. This structure has been determined to be eligible for the National Register of Historic Places. No pile driving is assumed to be required at the Oakland Touchdown.
Replacement Alternative N-6. No buildings are within the ranges for potential impact due to pile driving on YBI or at the Oakland Touchdown.
Replacement Alternative S-4. No buildings are within the ranges for potential impact due to pile driving on YBI or at the Oakland Touchdown.
Blasting may be required for in-Bay construction of replacement alternatives, cable stayed and self- anchored suspension design variations. The in-Bay blasting and rock excavation would be used to create a rock bench in the sloping bedrock off YBI for the main span tower foundation. A rock bench would be excavated at the tower site. Assuming the rock bench is to be located at an average elevation of approximately -22 meters (-72 feet), the rock blasting would take place from -10 meters to -25 meters (-33 feet to 82 feet) below water level.
The most economical and efficient method of blasting the rock would be to drill all the blast holes and set off one large explosion using millisecond delays. The rock bench is required for drilling the cast-in-drilled-holes piles. Approximately 25 footings would need to be drilled into the rock bench to support the main tower. This would require the removal of approximately 10,000 cubic meters (353,100 cubic feet) of rock. Using an average of seven pounds per cubic-meter of drilled rock, it is estimated that approximately 31,818 kilograms (70,000 pounds) of explosive would be required. The explosives that are normally used in consolidated rock formations are water gels, which can be pumped through a square shaft that drives the drilling bit. If this one explosion generates shock waves that are not acceptable, the area could be divided into two or three sections and then separate drilling and blasting of each section could be possible; however, this requires added time and expense. If the excavation area is divided into two or more sections, then the recommended procedure would be to drill, blast, and excavate the first section, before drilling the next section. This procedure would have several explosions spaced days or weeks apart, depending on the amount of time required to drill, blast, and excavate each section. The total duration of the blast would be 500 milliseconds (one-half second), assuming 50 millisecond delays between drill hole rows for 10 rows. This total time would apply to one explosion or to three separate explosions, as the number of rows would not change. It is also recommended that all overburden, approximately 2 to 5 meters (7 to 16 feet) deep, be excavated down to the rock layer prior to starting the drill and blast operations.
Building 262 sits below a rock bluff at the eastern tip of YBI. The N-2 and N-6 replacement alternatives propose constructing one of the bridge piers on the bedrock on this rock bluff, approximately 25-30 meters (82-100 feet) from Building 262. Explosives may be utilized during foundation construction for this pier.
Abatement. Caltrans will require project contractors to use cast-in-drilled-hole piles if feasible when working at the easternmost pier near Building 262 and to monitor the building during periods of pile driving. The monitoring would consist of, at a minimum, photographic documentation of the building prior to pile driving to determine if there is damage. Sensors could also be installed to monitor vibration. If the monitoring indicates there has been damage to the building, the building will be repaired consistent with the Secretary of the Interiors Standards for Rehabilitation and Guidelines for Rehabilitating Historic Buildings.
If explosives are used, a detailed analysis will be conducted prior to blasting to ensure that noise and vibration is minimized. Measures would be developed to control distribution of rock debris. Notifications and conditions would be developed in consultation with the California Department of Fish and Game and Notice to Mariners required by the USCG.
4.14.6 Hazardous Wastes
The potential for encountering pre-existing hazardous wastes is present during any construction project, particularly in the East Span Project area where hazardous wastes sites are known to exist. Hazardous wastes impacts would occur if construction workers or members of the public were exposed to hazardous wastes during grading and excavation activities, or if the likelihood of hazardous waste migration were increased by construction activities.
Potential sources of contamination have been identified within all of the project alternative alignments. Areas known or likely to contain contaminated soil and/or groundwater were identified in Section 3.6 of this report.
Mitigation. Demolition 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 accordance with federal regulations (29 CFR 1910.120), as well as state regulations (CCR Title 8 G1505192). In order to reduce the risk of exposure, a Worker Health and Safety Plan would be prepared by a Certified Industrial Hygienist (CIH). The Health and Safety Plan would include provisions for:
The plan would specify mitigation of potential worker and public exposure to airborne contaminants by incorporating dust suppression techniques in construction procedures. Procedures would be in place to handle contaminated soils.
4.14.7 Water Resources and Water Quality
The project could have potential adverse impacts on water quality related to construction activities. These include, but are not limited to: exposure of soils potentially resulting in erosion impacts to receiving waters; footing excavations for pier foundation resulting in possible groundwater contamination; potential surface water impacts from dredging and dewatering operations, concrete pouring, and washout activities, management and application of chemical products; construction activities performed on barges; and the potential for accidental spills from construction equipment and materials. Additional construction-related impacts are associated with the dismantling of the existing East Span, which may include discharges of waste material, accidental spills, and resuspension of bottom sediments. Measures similar to those taken during construction will be taken to address these impacts.
The area occupied by this project is under the jurisdiction of the San Francisco Bay Regional Water Quality Control Board; therefore, National Pollutant Discharge Elimination System (NPDES) Permit No. CAS029998 applies to the project facilities during construction. The NPDES permit requires that a Storm Water Pollution Prevention Plan (SWPPP) be prepared for any construction project that disturbs an area greater than five acres or for any project that is located within or near a water-related sensitive environment.
Construction work would include dredging, dewatering, concrete pouring, welding, paint and paint removal, and other activities that have the potential to impact water quality. Preventing these impacts may be difficult due to the complex site conditions, with limited space and several constraints. However, controls in the SWPPP would be used to minimize water quality effects to the maximum extent practicable. The SWPPP would have a plan for responding to and managing accidental spills during construction, a plan for the management of chemical and/or hazardous materials used during construction, a plan for management and performance of all construction activities conducted over water and from barges to minimize the potential for accidental releases, a plan for the management of excavation activities to minimize or eliminate the potential for groundwater contamination resulting from such activities, and a plan for the management and disposal of all pumped water and dredged materials. The SWPPP would also address overall management of the project, such as Best Management Practices for concrete pouring, the application of concrete curing compounds, material storage, equipment fueling, concrete washout, and stockpiles. The transport of materials and equipment use would also be covered.
The SWPPP would describe all erosion control measures to be taken by the contractor as well as all Best Management Practices to be implemented to control and prevent to the Maximum Extent Practicable the discharge of pollutants to surface waters as well as groundwater. Erosion control measures may include, but not be limited to, the installation of silt fences on cut slopes, around drainage inlets, and any drainage path; placement of hay bales, mulching; erosion control blankets; and hydroseeding.
Since the dismantling work is being performed under a separate contract, a separate SWPPP specific for the demolition work will be prepared. The SWPPP will address specific dismantling activities and BMPs to be implemented to minimize the discharge of pollutants associated with these activities. Similar to the SWPPP prepared for the construction of the new structure, this SWPPP will have a plan for managing and responding to accidental spills and discharges of waste material.
4.14.8 Natural Resources
Impacts to natural resources could result from construction activities on land at YBI and the Oakland Touchdown area and in open water. Impacts to natural resources on land include in-Bay construction work or temporary disturbance of habitats for special status species, wetland areas, or other special aquatic sites.
Retrofit Existing Structure Alternative
Special Status Species. Temporary impacts associated with construction activities would occur to the American peregrine falcon, double-crested cormorant, chinook salmon, steelhead, green sturgeon, and longfin smelt. A summary of mitigation measures, which are described in the 1996 Biological Assessment prepared for the retrofit alternative and in the 1997 Biological Opinion, is provided following the impact discussion.
American Peregrine Falcon. The seismic retrofit work may cause temporary impacts to the peregrine falcons during their reproductive cycle. The peregrine falcon pairs are habituated to two known nest sites, located on the East Span at Pier E2. Construction activities on the East Span could induce defensive reactions by the peregrines during the nesting season, which can adversely affect breeding success by diverting adult energies away from breeding activities. Such disturbances could jeopardize egg laying and rearing.
Double-crested cormorant. Work at piers E5 through E15 along the eastern span would potentially affect the double-crested cormorant colony nesting on the bridge. Nesting activities may occur any time within the breeding season between March and mid-September. Construction work during this time period could disrupt some or all of the nesting or attempted-nesting activities.
Winter-run, Spring-run, and Fall-run Chinook Salmon. Mobilization of sediments and increased turbidity could disrupt chinook salmon runs. Seismic retrofit of the East Span may involve dredging and removal of about 300,000 cubic meters (392,000 cubic yards) of material from the Bay. Adverse modification to chinook salmon critical habitat is not expected since the designated critical habitat is located to the north of the bridge.
Steelhead. Migration periods for both the Central Valley steelhead and Central Coast steelhead are similar to that of the chinook salmon. Potential impacts to steelhead are expected to be similar to those for chinook salmon.
Green Sturgeon. Sediment mobilization and turbidity from retrofit construction activities, such as dredging, may adversely affect this species. Although adult sturgeon may be present in the Bay all year, more sensitive periods occur when juveniles are present during the winter and spring months.
Longfin Smelt. This species is not generally present within this portion of the Bay due to the relative high saline conditions. It could be affected by retrofit construction if present during heavy rainfall and runoff years. Thus, during construction of the retrofit project, contaminants and sediments in the Bay waters could be mobilized and increase turbidity, which would affect the longfin smelt, if it is present.
Mitigation for Special Status Species
American Peregrine Falcon. In prior consultation concerning the East Span retrofit proposal, Caltrans and the USFWS have developed mitigation approaches to avoid impacts to this species. Mitigation is discussed in the 1997 Biological Opinion and includes monitoring activities of the nesting pair on the East Span and releasing any chicks present to an off-site location.
Double-crested Cormorant. In prior consultation with USFWS, mitigation for impacts to this species would include excluding them from nesting along areas of the existing East Span. This mitigation is outlined in a 1997 Biological Opinion for the retrofit alternative. After construction activities are complete, double-crested cormorants would most likely recolonize the East Span bridge structure.
Chinook Salmon, Steelhead Trout, Green Sturgeon, Pacific Herring, and Longfin Smelt. There will be no direct impacts to special status fish species from the Retrofit Existing Structure Alternative. To minimize turbidity and sediment mobilization during dredging and construction of cofferdams, silt curtains would be installed around work areas.
Caltrans will require that periodic water quality inspections be conducted, particularly during dredging activities, to ensure that actions to minimize turbidity and sediment mobilization are in place.
Replacement Alternatives N-2, N-6, and S-4
Special Status Species.
American Peregrine Falcon. Noise generated by the construction of a replacement alignment alternative could affect breeding and nesting of this species. Mitigation measures would include the continuance of the monitoring and release efforts outlined in the contract between Caltrans and the Santa Cruz Predatory Bird Research Group, described above, for the interim seismic retrofit projects.
Double-crested Cormorant. During the construction of a replacement alternative, noise could affect the breeding and nesting of this species. Caltrans would monitor the double-crested cormorant colony during breeding season and prevent them from nesting on the existing bridge where potential impacts could occur by construction activities. The protocol to prevent double-crested cormorants from nesting would follow the methods implemented for maintenance activities on the existing bridge; this protocol involves washing partially constructed nests off the bridge with hoses. If the nests are completed and the birds have laid eggs, the nests cannot be disturbed.
Harbor Seal. Vibrations from blasting and pile driving activities may harass the harbor seals when resting at the haul-out site near the existing USCG station on the southwest side of YBI or foraging in the surrounding waters. Appropriate mitigation measures to avoid impacts to harbor seals are currently being developed in consultation with the National Marine Fisheries Service (NMFS). These will include a restriction on the use of explosives during the winter months when the harbor seals are using the haul-out site on YBI. The harbor seal haul-out site will be monitored periodically during construction activities to determine if seals are substantially disturbed even with these measures. If so, additional consultation with the NMFS will be initiated. During construction activities using explosives, a biological monitor will be present and conduct transects within a 1,000-yard safety zone from the proposed blasting location. Blasting activities will only occur when the harbor seals are not present within the safety zone. If the construction time constraint cannot be applied and impacts cannot be avoided, an Incidental Harassment Authorization permit will be obtained from the NMFS as required by the Marine Mammal Protection Act under Section 10 (a)(5).
Winter-run, Fall-run, and Spring-run Chinook Salmon, Central California-Coast Steelhead, and Central California-Valley Steelhead (ESUs). Dredging activities associated with barge access would likely result in localized elevated suspended sediment concentrations with the potential for introduction of toxic contaminants in the water column. Mitigation measures to avoid and minimize impacts to fish and chinook salmon critical habitat would include measures such as the selection of certain dredge types (e.g., the cutterhead dredge, which may lower concentration of suspended materials) and the use of physical barriers such as silt curtains to contain the sediment plume and reduce suspended sediment concentrations in adjacent waters. If construction sequencing permits, dredging would be avoided in shallow water during the peak juvenile outmigration period (January 1 through May 31) in areas that are too large for a silt fence to be practicable,.
Construction activities, including blasting, could also adversely affect these fish species. To avoid impacts, blasting would occur, if construction sequencing permits, during the summer, from June 1 to October 1.
Green Sturgeon, and Longfin Smelt. Implementation of mitigation as described for the chinook salmon and steelhead would also reduce potential impacts to the green sturgeon and longfin smelt. To avoid impacts, blasting activities would occur during the summer, June 1 to October 1. Caltrans will consult with NMFS to determine protective measures if explosives must be used during this period.
Pacific Herring. An increase in sedimentation which could affect spawning of the pacific herring is and will continue to be monitored by the CDFG. Construction activities that occur during the seasonal herring spawning, generally December to March, will be monitored by a qualified biologist to watch for the presence of spawning herring. If the monitoring biologist (or CDFG) observes spawning in the project area, in-water construction activities, such as pile driving and dredging, will be suspended within 200 meters (656 feet) of observed spawn. In-water construction activities would not resume at that location for a period of up to 14 days (as determined by a qualified biologist), allowing herring eggs to hatch and larvae to disperse.
Blasting activities will be avoided during the spawning season, December to March. The use of explosives under water will require monitoring by a CDFG biologist during and after the explosion. The monitor will record the number and type of fish species affected by the explosion. Measures to minimize impacts associated with blasting will be developed with resource agencies and included in the conceptual mitigation plan to be discussed in the final EIS.
4.14.9 Construction Excavation and Dredging
Each of the build alternatives would require excavation on land an in-water dredging to retrofit existing or place new piers and to allow construction equipment access to construction sites. Disposal of materials could occur at upland disposal sites. Selected dredge materials would be disposed of at approved in-Bay disposal sites.
Anticipated construction scenarios and dredge quantities for the build alternatives are discussed in Section 2.6. Excavation requirements of the alternatives are presented below.
Retrofit Existing Structure Alternative
Bridge retrofit would include work on YBI, Oakland Touchdown, and in-Bay requiring excavation of materials. Upland work would consist of excavation to expand and encase existing columns and piers on YBI in concrete. Excavated materials on YBI will include soils and rock. These materials would be disposed of at an upland location yet to be determined.
In-Bay construction work for the Retrofit Existing Structure Alternative would require the construction of cofferdams at each existing pier. Sediments (comprising dredged material) would be pumped out of the cofferdams and the densest portion of this material, estimated to be approximately five percent, could be disposed of in-Bay and the remainder would be disposed of at an upland site (final percentages to be determined by DMMO). Estimated excavation quantities for the Retrofit Existing Structure Alternative are presented inTable 2.6-1.
Construction scenarios for the retrofit alternative would permit work in shallow water areas to take place from temporary construction trestles, shallow-draft barges, or conventional barges. Construction trestles would be constructed along both sides of the existing East Span from the Oakland Touchdown area eastward until water depths allow for standard barge access, a minimum draft of 3.66 meters (12 feet). Excavation volumes for placing trestle piles is shown inTable 2.6-1. The use of conventional barges would require dredging of the shallow water at the Oakland Touchdown area to 3.66 meters (12 feet). Dredging activity would occur along the western edge of the Oakland Touchdown area only and would not encroach into the mudflat areas on the northern shore. Shallow-draft barges could also require dredging for clearance, depending on the type of barge selected and the nature of the construction activity.
Replacement Alternatives N-2, N-6, and S-4
As described in Section 2.6, construction of the replacement alternatives would include work on YBI, Oakland Touchdown and in-Bay that would require excavation of materials. Upland work will consist of excavation to place footings for columns and piers on YBI and the Oakland Touchdown. Excavated materials on YBI would include soils and rock. These materials would be disposed of at an upland location yet to be determined.
Excavation at the Oakland Touchdown would be required to place piers to support the structures as they come to grade. Bridge roadways may need to be on pile-supported fill to avoid settling on existing unstable fill. Soils excavated at the Touchdown would be disposed of at off-site locations. Some of the soils may contain hazardous materials and would require disposal at approved upland sites.
In-Bay construction activities would include dredging to allow construction barges to reach construction sites. Anticipated construction techniques for replacement alignment alternatives would require the use of large-scale construction equipment mounted on barges. Construction work for the replacement alignment alternatives is expected to be conducted from barges requiring a minimum draft of 3.66 meters (12 feet). Where water depths are less than minimum barge draft, access dredging would be necessary. Anticipated dredge volumes for construction barge access are presented inTable 2.6-1.
In-Bay work to dismantle the existing East Span would require excavation to remove existing bridge piers. Cofferdams would be constructed at each pier to remove pile caps, piers, and footings down to the existing mudline. Divers could also be used to place explosives or chemicals to break up pile caps, piers, and footings for removal. Different approaches to pier removal are under consideration. One approach would use standard draft barges similar to those proposed to construct replacement alternatives. This would require access dredging on one side of the existing East Span to allow barge access. Sections of the existing bridge would be lowered into barges for removal to onshore sites for further dismantling. Estimated excavation volumes for removal of the existing East Span are summarized inTable 2.6-1. Excavation volumes for materials potentially eligible for in-Bay disposal and upland materials are segregated in the table.
Mitigation. Disposal of excavated materials would require permits and approvals from federal, state and regional permitting agencies. Following identification of a preferred alternative, Caltrans would initiate consultation with agencies, including the ACOE, BCDC, RWQCB, USFWS, CDFG, and California EPA (DTSC), to gain permits and approvals to dispose of materials at specified in-Bay and upland sites.
Some soils excavated on YBI and at the Oakland Touchdown area are expected to contain hazardous materials that would require disposal at approved upland sites.
Bay muds excavated for access dredging under all build alternatives would be disposed of at an approved in-Bay disposal site, pending approval of permitting agencies. Consultation with the DMMO has been initiated to determine appropriate in-Bay disposal sites.
4.15 CUMULATIVE EFFECTS
4.15.1 Regulatory Setting and Methodology
Federal Council on Environmental Quality NEPA regulations require that the cumulative effects of a proposed project be addressed in an EIS (40 CFR §1508.25). Cumulative effects are effects on the environment that result from the incremental impact of the proposed action when added to other past, present, and reasonably foreseeable future actions (40 CFR §1508.7). These effects can result from individually minor but collectively significant actions taking place over time. Frequently, mitigation of such effects must rely upon regulatory programs when they are attributable to actions outside of an agencys jurisdiction. For instance, while specific project effects on natural habitats may be mitigated by modification of a projects design, regulations of the California Department of Fish and Game, U.S. Army Corps of Engineers, and the National Marine Fisheries Service would address potential adverse habitat effects of development accommodated by the project. The specific development project proponent would be responsible for mitigation of these cumulative effects.
The analysis of cumulative effects in this EIS addresses cumulative impacts of the SFOBB East Span project in general with no separate analysis for each alternative.
This cumulative effects section identifies past, present, and reasonably anticipated future projects producing related or cumulative impacts, on resources (e.g., wetlands and cultural resources) and traffic-related impacts (e.g., noise and air quality) including other Caltrans projects and projects proposed by other agencies and developers outside the control of Caltrans. For this section, information sources examined for projects that may contribute to cumulative impacts include the BCDC Bay and Seaport Plans, the development plans of the Port of Oakland, the cities of Oakland, Emeryville, and the City and County of San Francisco. No specific shoreline projects other than the Port of Oakland projects are proposed at this time for the City of Oakland and no shoreline projects are currently proposed for the City of Emeryville. The analysis is presented by resource and includes a discussion of the expected cumulative environmental effects to be produced by the SFOBB East Span project in combination with other projects in the area.
For this EIS, cumulative impacts are considered to be those impacts resulting from the project, together with impacts from foreseeable development in the area proposed by the agencies and jurisdictions noted above. The impacts are considered to be cumulative when they contribute to effects on the same types of resources that are affected by the East Span project. The projects considered for cumulative effects for the East Span Project include the following:
City and County of San Francisco
Port of Oakland
Seismic Safety Projects
4.15.2 Local Context
Potential cumulative effects can either be regional in scale or of a local nature, where they may be considered less than significant at the project site, but could become significant when considered with other reasonably foreseeable future projects in the area. Reasonably foreseeable future projects are here defined as the projects listed above, which are closest to the East Span Project and have the potential to affect traffic and resources in the project area. Because the I-880/Cypress Freeway Replacement Project is nearing completion, and mitigation measures are fully developed, it is assumed to be complete for purposes of this section. Project-related land use, air quality, and noise effects reported earlier in this chapter would be the same as cumulative conditions, because the analyses addressed planned future land use concepts on YBI and at the Oakland Touchdown area and future planned transportation facilities as evaluated by MTC for the RTP and TIP.
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