4.6 UTILITIES and energy

4.6.1 utilities

Each Central Subway alternative alignment has extensive underground and above ground utilities serving the residents and businesses adjacent to the alignments.  The primary utilities serving the Corridor are:

· City and County of San Francisco Public Utilities Commission (PUC) underground sewer system;

· City and County of San Francisco Water Department (SFWD) potable water lines;

· San Francisco Fire Department (SFFD) auxiliary water supply service (AWSS) lines;

· Pacific Gas and Electric (PG&E) underground natural gas lines;

· PG&E electrical transmission and distribution lines and ductbanks (overhead and underground);

· AT&T underground and overhead telecommunications lines (although AT&T has the most extensive network of underground telecommunications cables, MCI, Sprint, and various other telecom providers also have a limited number of underground cables in the Corridor);

· NRG Energy Center steam lines;

· Municipal Railway (Muni) traction power ductbanks and overhead contact system.

Other utilities in the Study Area include:

· Electrical and communications vaults located along the ductbanks alignment to facilitate the installation of conductors and cables;

· North Point trunk sewer line (96-inch) which runs below Mission Street, crosses under Third Street, and continues to Fourth Street where it turns south to Howard Street and continues west on Howard Street;

· Sewer manholes used for maintaining the sewer mains;

· Water main gate valves and other appurtenances for isolating sections of the main for maintenance;

· Service laterals to adjacent residences and businesses for all utilities.

4.6.2 energy

Transit Traction Power System

More than half of Muni’s transit fleet--trolley buses, cable cars, streetcars, and light rail vehicles--use electrical power for operation.  The diesel buses are the only mode that uses fossil fuel.  Muni’s electric fleet operates with power that is generated at the San Francisco Public Utilities Commission (PUC) Hetch Hetchy hydroelectric facility in the Sierra foothills, and is distributed via a long distance transmission system to customers in San Francisco and the Peninsula.  Under City agreements, Hetch Hetchy provides power to Muni that is transmitted to the electric fleet through Muni’s traction power substations and overhead wire system.  The trolley bus and rail modes each have their separate substations and overhead systems.  Four new traction power substations and a new overhead wire system were built along the Third Street Corridor as part of the Phase 1 for the T-Third line. 

4.7 geology AND SEISMICITY

4.7.1 Topography

The topography of the Study Area is characterized by a series of gently sloping hills with intervening alluvial-filled valleys.  The Central Subway alternative alignments start in the flat-lying area south of Brannan Street, near Mission Creek, where the surface elevation is approximately 0 feet San Francisco City Datum (SFCD).[43]  The topography of the Study Area gently slopes upward along the alignment reaching a high point ground elevation of approximately 172 feet SFCD at Stockton and California Streets, where it begins to slope downward.[44]  The ground surface elevation at Stockton and Washington Streets terminus is approximately 102 feet SFCD and approximately 70 feet on Columbus Avenue, near the terminus of the North Beach Construction Variant.  The approximate surface elevations along other portions of the alignment are presented in Table 4-22.

TABLE 4-22

APPROXIMATE SURFACE ELEVATIONS

ALONG CENTRAL SUBWAY ALIGNMENTS

Notes:     SFCD = +8.616 feet National Geodetic Vertical Datum

Sources:  USGS, 1973, San Francisco North Quadrangle, 7½-minute series (Topo).

                                                USGS, 1980 San Francisco South Quadrangle, 7½-minute series (Topo).

                                                ICF Kaiser, 1996, Central Subway Alignment, Plan and Profile, October.

4.7.2 GeologY

San Francisco is located in the Coast Range geomorphic province of California.  The regional topography is characterized by relatively rugged bedrock hills surrounded by flat, low-lying valleys underlain by

Quaternary sedimentary deposits or artificial fill.  Bedrock in the area consists of the highly deformed Franciscan Formation.[45]  The Study Area is underlain by four general types of near-surface geologic material: 1) bedrock, 2) dune sand, 3) artificial fill, and 4) surficial deposits.[46]^,[47]

Along the Central Subway Corridor, the Fourth Street tunnel and surface alignment is located in an area of artificial fill.  The Third Street tunnel and surface alignment is located in an area of surficial deposits that extends north from approximately Townsend Street.  Dune sand deposits are encountered from approximately Harrison Street to Geary and Sutter Streets.  Bedrock is encountered from approximately Geary Street to the northern end of the alignment in the Chinatown area.[48]^, [49]

Bedrock

Bedrock is present in the Study Area at depths ranging from over 249 feet to outcropping at the surface.[50]  The bedrock consists of the Jurassic- to Cretaceous-aged Franciscan Formation.  The Franciscan Formation varies in composition, consisting of graywacke sandstones, shales with thin-bedded sandstones, cherts and shales, and intruded serpentine.  Exposed bedrock in the Study Area consists of graywacke sandstones in the Nob Hill area.[51]  Locally, bedrock has been crushed and sheered through geologic and tectonic processes making their engineering properties variable.[52]

Dune Sand

Over half of the City of San Francisco is underlain by Quaternary-age dune sand.  The sands are wind-deposited from sources historically located near Ocean Beach.  The sands are fine- to medium-grained, well sorted, and generally yellowish brown in color.[53]  Thickness of the sand in the Study Area along Third Street ranges up to 98 feet.[54]  In places within the Study Area, the dense sands are overlain by artificial fill.  The engineering properties of the sand vary depending on the level of saturation.  Saturated dune sand is susceptible to liquefaction; unsaturated, well compacted sand provides moderate to high shear strength, when confined.[55]

Artificial Fill

Much of the Study Area consists of fill areas where fill materials were deposited on Bay Mud or directly into open waters of the Bay.[56]  The practice of creating land by placing fill on tidal flats along the eastern margins of San Francisco began in the 1800s.[57]  Fill was placed on mudflats and in estuaries within the South of Market areas of the Central Subway Corridor. 

The fill material generally consists of clay to cobble-sized material including dune sand that was excavated during the development of San Francisco and hauled to the waterfront and dumped on top of the Bay Mud or other surface deposits.  The fill also includes building demolition rubble (concrete, bricks, and wood) from the 1906 earthquake and fire.[58]  Organic and inorganic debris, refuse, and other materials were also deposited in the fill areas.

In many areas, the fill is underlain by a soft, silty clay (Bay Mud).  The Bay Mud has a high water content, is plastic, weak, and highly compressible.  When overlain by fill, it becomes unstable.[59] Thickness of the Bay Mud reaches to a depth of over 25 feet in the Study Area.[60]  Because the fill was largely placed before or around the 1950s, there was little control or engineering of the fill.  Therefore, the material is highly variable with respect to compaction and settlement.  Where the fill is saturated in low-lying areas, it is also subject to liquefaction during earthquakes.  Numerous fill areas within the Study Area experienced differential settlement, ground failure, and surface cracking during the 1989 Loma Prieta earthquake.

Surficial Deposits

The valleys between the bedrock hills of the Study Area are generally filled with unconsolidated surficial deposits consisting of Quaternary age slope debris and ravine fill or alluvial deposits.  These deposits have been variously classified by different geologists and are not well differentiated in the Study Area.  The slope debris and ravine deposits generally consist of angular rock fragments in a matrix of sand, silt, and clay derived from nearby bedrock hills.  Transportation of materials downslope was mostly through colluvial processes such as creep, mud flows, and debris flows.  Alluvial deposits were generally associated with historic streams, such as Mission Creek, located just south of the Study Area.  These undifferentiated deposits can reach up to 100 feet in thickness within the Study Area.[61]  The engineering characteristics of these materials is highly variable depending on the nature and origin of the deposits.[62]

4.7.3 SeismiciTY

The City of San Francisco and the Study Area are located in a region of northern California with a high degree of seismic activity.[63]  There are no known active faults that traverse the Study Area; however, several nearby active faults could affect the area.  Significant regional faults that could serve as sources of seismic activity include the San Andreas Fault, located approximately 8 miles west of Downtown; the Hayward Fault, located in the East Bay approximately 9 miles east of Downtown; the Calaveras Fault, located approximately 25 miles east of Downtown; the Rodgers Creek Fault, located approximately 25 miles northwest of Downtown and the San Gregorio Fault, located approximately 14 miles west of Downtown. 

Active faults in the Bay Area are presented in Table 4-23.  Inactive faults within the City of San Francisco are unlikely to generate earthquakes, but numerous other active faults in northern California can generate earthquakes.  Earthquakes generated from active faults can generate significant seismic hazards within the Study Area.  This was evidenced in the 1989 Loma Prieta Earthquake, where the epicenter was located over 62 miles from San Francisco.

The measure of an earthquake’s magnitude (M) is reported in moment magnitude (M_w); a measurement of the energy released by the earthquake.  Moment magnitude is calculated based on the length and width (area) along the fault plane that experienced movement.  It has commonly replaced the familiar Richter (or "local") magnitude (M_L) due, in part, to the difficulty in differentiating the size of large (larger than M_L 7-1/2) magnitude earthquakes.[64]

The California Department of Conservation, Division of Mines and Geology (CDMG) has developed estimates for parameters related to future activity for major faults in California based on length, width, and slip rate.  Using these parameters, maximum moment magnitudes (M_max) have been developed for

TABLE 4-23

MAJOR SAN FRANCISCO BAY AREA

EARTHQUAKE FAULTS AND THEIR MAXIMUM MOMENT MAGNITUDE

Notes:     mm = millimeters.

Slip rate based on historic earthquake records and geologic evidence.

                M_max = Maximum moment magnitude.

                Return interval calculated using slip rate in relation to the displacement occurring during the M_max earthquake.

                NA = Not calculated by CDMG.

Sources:   California Department of Conservation, Division of Mines and Geology, 1996, California Fault Parameters, San Francisco Bay Area Faults               

Wells, D.L. and Coppersmith, K.J., 1994, New empirical relationships among magnitude, rupture length, rupture width, rupture area, and surface displacement.  Seismological Society of America Bulletin, v. 84, no. 4, pp.  974-1002.

each segment of major faults.[65]^, [66]  The slip rate of a fault is estimated based on historic earthquake records and geologic evidence.  Although earthquakes cannot be predicted, return intervals are calculated using the slip rate in relation to the displacement occurring during the M_max earthquake.[67]  Major faults proximate to the Study Area, their M_max, return interval, and distance from Downtown San Francisco are presented in Table 4-23.  The Working Group on California Earthquake Probabilities has estimated that there is a 62 percent probability that one or more major, damaging earthquakes (M_L 6.7 or greater) will occur in the San Francisco Bay Region during the 30-year period between 2002 and 2031.[68]

The Bay Area faults with the greatest slip rates include the San Andreas Fault, Hayward/Rodgers Creek Fault, Calaveras Fault, and San Gregorio Fault.  Each of these faults have displayed evidence of historic earthquake activity and have potential to generate large-magnitude earthquakes.  The 1989 Loma Prieta Earthquake had a M_w of 6.9; while the 1906 San Francisco Earthquake is estimated to have had a M_w of approximately 7.9.[69]

The design parameters to be used for construction under the 1994 Uniform Building Code (UBC) Section 1629A.2.6 require the determination of a Design-Basis Earthquake (DBE) for each specific project location.[70]  The DBE is defined as the seismic event that has a 10 percent chance of exceedance in 50 years.[71]  It is specific to a project location and is based on the M_max of earthquakes for all faults located within reasonable distance of the project and the seismic characteristics of the geologic material underlying the project.  The DBE calculation results in the determination of a specific set of ground motion values (measured by a strong motion seismograph as the acceleration of gravity) for a project site.

The ground motion values for the Study Area will vary along the alignment.  Ground motion values must be carefully developed for the Study Area to determine appropriate DBE parameters.  The DBE parameters for this Project will require evaluation using the International Building Code (IBC) 2003 standards which vary from the 1994 UBC standards and will be established during Project design.[72]^, [73]

Groundshaking

The occurrence of an earthquake produces seismic waves that emanate in all directions from the origin of the earthquake, or epicenter.  The seismic waves cause groundshaking, which is typically strongest at the epicenter and diminishes (attenuates) as the waves move through the earth away from the source of the quake.  The severity of groundshaking at any particular point is referred to as "intensity" and is a subjective measure of the effects of groundshaking on people, structures, and earth materials.[74]  The effects of groundshaking on structures depends on the design, quality of construction, and foundation materials.  A critical factor affecting intensity at a site is the geologic material underneath that site.  Deep, loose soils tend to amplify and prolong the shaking; soft clay and silty clay amplify the most.  Igneous rock amplifies ground shaking the least.[75]

During an earthquake, portions of the Study Area are subject to higher groundshaking risks than others.  Where the underlying geologic material consists of unconsolidated sediments, artificial fills, and Bay Mud, groundshaking during an earthquake can be amplified, resulting in greater damage to structures.[76]  The ABAG has mapped and classified San Francisco according to groundshaking amplification.  The Study Area is located within areas classified from "Extremely High" shaking amplification, the highest risk classification, to "Low" shaking amplification.[77]  The areas of high amplification are those where the underlying geologic materials consist of artificial fill, dune sand, and surficial (alluvial/colluvial) sediments. Higher risk areas are typically underlain by Bay Mud, as present in the South of Market area. The areas of lower amplification are those underlain by bedrock in the Nob Hill area.

Liquefaction

A secondary effect of amplified ground shaking in unconsolidated (cohesionless) sediments, such as silts and sands, is liquefaction.  Liquefaction occurs when saturated, cohesionless soils become "liquid" due to groundshaking.[78]  When a soil liquefies, it loses its load-bearing strength.  Liquefaction can result in a drop in the ground surface or cause buckling, rippling, and cracking of the ground surface.  This can result in roads, rail lines, or buildings being displaced or severed.  Liquefaction resulted in differential

settlement, sand boils, and lateral spreading within the Study Area during the 1989 Loma Prieta Earthquake.  Geologic profiles of the Study Area for each alternative are shown in Section 5.7 of the SEIS/SEIR.

4.8 HYDROLOGY AND WATER QUALITY

4.8.1 Regulatory Framework

The U.S. Environmental Protection Agency (EPA) is responsible for enforcing the federal Clean Water Act of 1972 (amended in 1987).  The Clean Water Act (CWA) established the National Pollution Discharge Elimination System (NPDES) program to regulate municipal and industrial wastewater discharges.  The CWA provides that the discharge of pollutants to waters of the United States from any point source is unlawful, unless the discharge is in compliance with an NPDES permit.

In 1990, the EPA published final regulations that establish storm water permit application requirements for specific categories of industries.  The regulations require that discharges of storm water associated with construction activities from soil disturbances of five acres or more must be regulated as an industrial activity and covered by an NPDES permit.  On December 8, 1999, the EPA finalized regulations (Phase II Rule) which expand the existing NPDES program to address storm water discharges from construction sites that disturb land equal to or greater than one (1) acre and less than five (5) acres (small construction activity).[79]  In California, the EPA has delegated responsibility for the program to the state Water Resources Control Board (WRCB) and the California Regional Water Quality Control Boards (RWQCB).

The WRCB has adopted general NPDES permit requirements for owners of land where construction activities occur.  These requirements include:  1) elimination or reduction of non-storm water discharges to the storm sewer system, 2) development and implementation of a Storm Water Pollution Prevention Plan (SWPPP), and 3) inspections of storm water pollution prevention measures.  The RWQCB is responsible for adopting, monitoring, and enforcing compliance with the NPDES permit requirements and Waste Discharge Requirements for point and non-point sources.

San Francisco's combined storm and sanitary sewer system collects storm water and sewage and conveys the combined flows to wastewater treatment facilities; therefore, construction operations that drain to the sewer system are not required to comply with the general permit requirements for non-point source discharges or preparation of SWPPPs.[80]  However, under San Francisco Ordinance 19-92, Sections 118 and 123, discharges of materials, including soil, sand, or gravel that can obstruct the sewers are prohibited.[81]  Best Management Practices (BMPs) must be implemented at construction sites to ensure that unauthorized discharges do not occur.  During construction activities for the Project, BMPs for non-point source discharge control will be required.

The groundwater underlying the Study Area and the surface waters of San Francisco Bay constitute the receiving waters, which could be affected by implementation of the Central Subway Alternatives.  The Water Quality Control Plan for the San Francisco Bay Basin (Basin Plan) was first adopted by the RWQCB in 1975, and amended most recently in 2005, to implement state and federal laws requiring the preservation and enhancement of water quality.[82]  The Basin Plan identifies the beneficial uses of and water quality objectives for water resources within distinct subregions of the San Francisco Bay Region.  The Study Area is within the Central Bay subregion, an inland surface water resource.  Current beneficial uses include industrial process and industrial service water.  Potential beneficial uses include municipal and agricultural water.

The Basin Plan also defines water quality objectives for surface and subsurface waters within the San Francisco Bay Basin.  The water quality objectives specifically identify recommended contaminant concentrations for the protection of human health and aquatic life for the groundwater and the saline marine surface waters of the Bay.  The groundwater in the low-lying portions of the Study Area is brackish and is not typically used as a water supply source.[83]

During times of normal (dry and wet) weather, combined flows to the sewer system are treated prior to discharge to surface waters.  In some wet weather events, the Southeast and North Point treatment plants cannot accommodate all of the combined storm drain/sewer system flows, resulting in partially treated discharges to the Bay.  The points of discharge for wet weather overflows in the Study Area are located along the eastern waterfront.[84]^,[85]

Direct discharge of partially treated wastewater is allowed by the RWQCB under the Wet Weather Overflow Control Strategy under an NPDES permit issued by the RWQCB.[86]  The rationale for allowing the discharges recognizes that adverse impacts of the discharges on the beneficial uses of the Bay are minimal compared to the cost of eliminating wet weather overflows.

Protection of groundwater quality in the Study Area is also the responsibility of the RWQCB through authority under the Porter Cologne Water Quality Control Act of 1969.  Although the Study Area is not located within an area identified as a major groundwater basin and groundwater is not used as a municipal or domestic water supply, the RWQCB enforces the provisions of the State statutes, which protect groundwater resources.

The San Francisco Department of Public Health (DPH) implements the state underground storage tank regulations (California Code of Regulations Title 23) within the Study Area.  These regulations include the requirements for groundwater investigations in the case of fuel releases.

The San Francisco Public Utilities Commission (SFPUC) regulates the discharge and potential discharge of industrial wastewater, including dewatering effluent, to the combined sewer system under the San Francisco Public Works Code - Industrial Waste Ordinance and Department of Public Works Order No. 158170, which cites local discharge limits.  Discharges resulting from dewatering of construction sites, wells drilled to investigate or mitigate a suspect contaminated site, or any other activities which generate wastewater other than from routine commercial/industrial processes, must comply with the Requirements for Batch Wastewater Discharges issued by the BERM.[87]  The requirements specify analytical approaches and discharge limits for organic and inorganic constituents in discharges.  Applications for permits to perform batch wastewater discharges must be submitted to BERM for approval.  In areas along the alignment where groundwater dewatering will be necessary (for example, tunnels and underground stations), permits to perform batch wastewater discharges will be required.

4.8.2 Surface Water

The climate of the Study Area is characterized by near-shore Mediterranean conditions.  The mean annual temperature in San Francisco is 58° Fahrenheit.  Rainfall is variable throughout San Francisco and generally increases with elevation west of the Study Area.  The range of average annual rainfall within the Study Area is about 20 inches per year.[88]  More than 90 percent of the rainfall occurs between November and April.[89]

Runoff from paved urbanized areas, such as the Study Area, is recognized as a principle non-point source of pollutants contributing to water quality degradation.  The pollutants typically carried by urban runoff

include suspended sediments, heavy metals, and petroleum (particularly oil and grease components).  Roadway use contributes significantly to the generation of contaminants in urban runoff.  Tire and pavement wear, vehicle rust, mud, dust, and car exhaust produce solid particles on roadways.  Petroleum products leaking or spilled from vehicles and emitted with exhaust also accumulate on roadway surfaces.  Heavy metals are contributed through exhaust, corrosion or wear of metallic vehicle components, roadway structures, and tires.  These contaminants build up on the paved areas and are entrained in runoff during rainstorms.

Surface runoff throughout most of the Study Area is collected into the City's combined storm and sanitary sewer system.  The combined sewer system carries both sanitary sewage (municipal and industrial wastewater) and, during rainy weather, rainfall runoff from streets, sidewalks, and building roofs.  Streams or surface drainage systems are not located in the Study Area.

There are no perennial surface waters in the Study Area.  During times of dry weather, surface water flows from the Study Area are routed to the Southeast Water Pollution Control Plant located on Jerrold Avenue and Phelps Street, where they are treated and discharged to San Francisco Bay.  During rainy weather, the North Point Water Pollution Control Plant, located on Bay Street and The Embarcadero, is operational for the flows from the northern part of the Study Area; the Southeast Plant also processes wet weather flows.[90]  During major storms, the storage capacities of the combined sewers and the treatment plants are exceeded and combined flows of sewage and storm water overflow into the Bay through overflow points along the bayside waterfront.  There are a total of 28 overflow points along the bayside waterfront including Mission Creek.[91]^,[92]

4.8.3 Flooding/tsunamis

San Francisco does not participate in the Federal Emergency Management Agency's floodplain identification program and no flood plains have been identified within San Francisco.[93]  The Study Area elevations range from approximately 0 feet San Francisco City Datum (SFCD) at the southern end of the Central Subway Corridor at King and Fourth Streets, to a high point of approximately 172 feet SFCD along Stockton Street between Pine and California Streets.  At the north end of the Corridor along Columbus Avenue, the elevation is approximately 70 feet SFCD.[94] 

The 100-year high tide (the height that is equaled or exceeded with an average frequency of once every 100 years) would reach an elevation of approximately -2.0 feet SFCD.[95]  Inundation of the Study Area from a 100-year high tide would not be expected.

The projected sea level rise in the San Francisco Bay has historically been estimated to be approximately 1.25 feet in the next 100 years.[96]  However in the last 50 years, the rise in sea-level has increased by 0.023 inches/year, nearly double the previous rate.[97]  By 2100, using these modified rates, future sea-level rise due to the greenhouse effect can be projected to range from 20 inches to over 120 inches.[98]  An increase of 5 feet to the 100-year high tide (currently -0.7 feet SFCD) would result in an elevation of about +4.3 feet SFCD.

Portions of the Study Area are located near the landward edge of an area designated as possibly being inundated by tsunami waves generated by earthquakes.[99]  The potential tsunamis considered for the hazard evaluation would be similar to the wave produced by the 1964 tsunami from the Alaska earthquake which generated a wave run-up (height of wave above water level at the time of the event) of 7.40 feet at the Golden Gate.[100]  The narrow mouth of the Golden Gate limits the extent of tsunami incursion into the Bay; the run-up attenuates with distance from the Golden Gate.  The estimated run-up from a tsunami with 100-year return period (i.e., expected to occur once every 100 years, on average) range from 5.6 feet near the Ferry Building to 4.9 feet near China Basin. 

4.8.4 GROUNDWATER

The Study Area for the Central Subway alignment alternatives is underlain by the Downtown Basin as defined by the U.S. Geological Survey.[101]  The groundwater basin is separated by hills (bedrock outcrops) along the eastern portion of San Francisco and occupies the intervening valleys. 

Depths to groundwater in the Study Area are highly variable due to geologic and geographic conditions.  Groundwater occurs at depths along the Central Subway Corridor ranging from approximately 40 feet below ground surface near Stockton and Washington Streets to 10 feet below ground surface near Fourth and Harrison Streets.[102]  At Market Street, where the Central Subway tunnel would cross over or under the existing BART/Muni Metro tunnels, the groundwater table was last measured in 2005 to be approximately 25 feet below the surface.  Given the depth of the Powell Street Station, sump pumps are required to continuously pump water from the station at the rate of 100,000 to 500,000 gallons a day.

Within the Downtown Basin, the groundwater generally flows east toward the Bay.  Groundwater flows from areas of high head to areas of relatively lower head.  Therefore, the groundwater flows in the basins would be expected to be from the uplands and hills (recharge areas) toward lowlands and valleys (discharge areas). 

This pattern can vary locally due to unusual subsurface conditions, such as heterogeneous geology, steep slopes, and undulating bedrock topography.  Human activities such as groundwater pumping or injection can also affect the local groundwater flow direction.[103]

The dominant source of groundwater recharge in the Downtown Basin is leakage from the sewer and water delivery pipes, which form a dense network in the Downtown area.  Due to the relatively high water table in the Downtown Basin, dewatering operations are required for building foundations, underground structures (such as BART/Muni Metro stations), and construction sites.  This dewatering constitutes the primary source of discharge from the aquifer.  Most of the pumped groundwater is discharged directly to the City storm sewer system. 

The only known uses of groundwater in the Downtown Basin are limited non-potable uses such as fountains and HVAC systems.  Potential future uses of groundwater in the Downtown Basin would also be limited to non-potable uses, because the basin contains high levels of groundwater pollutions and meets the exemption criteria of the State Water Resources Control Board (SWRCB) Sources of Drinking Water Policy.[104]  Since the Downtown Basin is almost entirely covered with impermeable surfaces, leaking sewer lines provide the majority of the groundwater recharge.  In addition, historic industrial development and placement of artificial fill have contributed to the degradation of groundwater quality. 

4.9 BIOLOGICAL AND WETLAND RESOURCES

4.9.1 Special-Status Species

Special-status species are plants and animals that are legally protected under the state and/or federal Endangered Species Acts or other regulations, as well as other species that are considered rare enough by the scientific community and trustee agencies to warrant special consideration, particularly with regard to protection of isolated populations, nesting or denning locations, communal roosts, and other essential habitat. [105]  Special-status species include:

· Listed (rare, threatened, or endangered) and candidate species for listing by the California Department of Fish and Game (CDFG);

· Listed (threatened or endangered) and candidate species for listing by the US Fish and Wildlife Service (USFWS);

· Species considered to be rare or endangered under the conditions of Section 15380 of the CEQA Guidelines, such as those identified on lists 1A, 1B, and 2 in the Inventory of Rare and Endangered Vascular Plants of California by the California Native Plant Society (CNPS);

· Other species that are possibly considered sensitive or of special concern due to to limited distribution or lack of adequate information to permit listing or rejection for state or federal status, such as those included on lists 3 and 4 in the CNPS Inventory or identified as animal “Species of Special Concern” by the CDFG.  Species of Special Concern have no legal protective status under the state Endangered Species Act, but are of concern to the CDFG because of severe decline in breeding populations in California.

Based on occurrence information from the California Natural Diversity Data Basse (CNDDB), there are no special status biological resources in the Central Subway Study Area.  The nearest occurrence record in the CNDDB is a overwintering site for monarch butterfly at Telegraph Hill, approximately ¼ mile northeast of Washington Square at Columbus Avenue and Union Street. 

4.9.2 Wetlands

Although definitions used by jurisdictional agencies vary to some degree, wetlands are generally considered to be areas that are periodically or permanently inundated by surface or groundwater, and support vegetation adapted to life in saturated soil.  Wetlands are recognized as important features on a regional and national level due to their high inherent value to fish and wildlife, use as storage areas for storm and flood waters, and water recharge, filtration, and purification functions.  Technical standards for delineating wetlands have been developed by the US Army Corps of Engineers (Corps) and the USFWS, which generally define wetlands through consideration of three criteria: hydrology, soils, and vegetation. The Corps and CDFG have jurisdiction over modifications to stream channels, river banks, lakes, and other wetland features.[106]

A wetland assessment was conducted during the field reconnaissance surveys for the Third Street Light Rail project in July 1997.  Vegetative cover was used as the primary indicator of potential wetland habitat during the survey effort.  Due to the extent of development and past filling, jurisdictional wetlands and other water in the Study Area are not present.  The only wetlands identified during the 1998 EIS/EIR study for the Third Street Light Rail project were in the Mission Creek and Islais Creek channels.  There are no wetlands in the Central Subway Study Area.

4.10 HAZARDOUS MATERIALS

This section describes hazardous materials that could be encountered in the Study Area.[107]  This section also includes a description of the general regulatory framework for hazardous materials management and the nature and extent of hazardous materials known to be, or potentially, present in subsurface soil and groundwater within the Study Area.

This section summarizes information from detailed technical reports describing known soil and groundwater contamination and past and current land uses in the Study Area that may have affected or could potentially affect the quality of soil and groundwater.[108]^{,[109],[110],[111],[112]}  Existing reports and regulatory databases were reviewed to determine known areas of contamination and areas suspected of containing hazardous materials throughout the Study Area.  Previous reports, including site investigation reports, leaking underground storage tank site files, and EIS/EIR documents prepared for projects in the Study Area, were reviewed and independent regulatory records database searches, which included federal, state, and local data bases, were also conducted.  A Phase II Hazardous Materials Investigation (HMI) was conducted in 2005 to screen for the presence of contaminants of concern that could affect (1) the health and safety of construction workers and the public and (2) the handling and disposal of excavated materials and groundwater encountered during construction of the project.

4.10.1 Regulatory Framework

Hazardous materials and hazardous wastes are controlled by federal, state, regional and local regulations, with the objective of protecting the public health and environment.  In general, these regulations provide definitions of hazardous substances; establish reporting requirements; set guidelines for handling, storage, transport, remediation, and disposal of hazardous wastes; and require health and safety provisions for both workers and the public.  Sites that comply with hazards regulations are identified on periodically-updated lists at the federal, state, and local levels.

Agencies enforcing these regulations in San Francisco include: the U.S. Environmental Protection Agency (federal); the Department of Toxic Substance Control, California Environmental Protection Agency (state); the California Regional Water Quality Control Board (state); the Bay Area Air Quality Manage­ment District (regional); the San Francisco Department of Public Health, Bureau of Toxics, Health and Safety Services (local); and the San Francisco Fire Department (local).  A brief overview of the applicable hazardous materials regulatory requirements is presented below.

A portion of the Study Area is located in areas formerly bayward of the 1851 high tide line. Areas of the City located bayward of the 1851 high tide line are subject to the requirements of Article 20 (also known as the Maher Ordinance) of the San Francisco Municipal Code.  Article 20 requires that, if development is proposed bayward of the 1851 high tide line, and more than 50 cubic yards of soils are excavated, the following actions must be undertaken:

· Preparation of a site history report;

· Collection of soil samples in accordance with an approved work plan;

· Preparation of a soils analysis report; and

· Preparation of a site mitigation report.

Article 20 is administered by San Francisco Department of Public Health (DPH).  DPH reviews and approves all site history reports, sampling work plans, soil analyses reports, and site mitigation reports.  The site mitigation reports delineate remedies to be undertaken during project construction and operation to protect the public and the environment.  DPH coordinates the Article 20 documentation and mitigation with the State Department of Toxic Substances Control (DTSC) and the Regional Water Quality Control Board (RWQCB).

Discovery of hazardous substances in the subsurface, in areas not subject to the requirements of Article 20, could also result in investigation oversight by regulatory agencies.  Such oversight could be from DPH, DTSC, and/or RWQCB.  DPH may provide remedial action oversight for the cleanup of waste releases provided that the requisite technical expertise and capabilities are available to supervise the action.  DPH would be required to notify the DTSC and the RWQCB prior to the commencement of oversight.[113]

The majority of federal hazardous materials regulations has been incorporated into California’s hazardous materials regulations.  California’s hazardous materials statutes and regulations are contained in the California Health and Safety Code (HSC) Section 25130 et seq. and Title 22 of the California Code of Regulations (CCR).  Title 22 CCR is administered by the DTSC.

4.10.2 Waste Classification and Management

According to Title 22 CCR Section 66261, a waste is considered hazardous if it exhibits at least one of four specified characteristics (ignitability, corrosivity, reactivity, or toxicity) or if it is a “listed waste” (i.e., the waste is generated from a specific process).   A waste can be present in a liquid, semi-solid, solid, or gaseous form.

Waste types generated from public transit construction projects include pavement and roadbed debris, soils, and wastewater.  Pavement and roadbed debris is not a “listed waste” and generally does not exhibit hazardous characteristics.  Waste soils are also not a “listed waste” and generally are not ignitable, corrosive, or reactive.  Excavated soils could be hazardous by exhibiting the toxicity characteristic.  Excavated soils would constitute a hazardous waste based on toxicity characteristics, if representative samples collected from the soils contain concentrations of contaminants listed in Title 22 CCR Section 66261 at levels exceeding the specified limit, which would define the waste as either a Federal hazardous waste (RCRA Waste) or a California hazardous waste.

Waste containing friable, finely divided, and powdered asbestos at levels equal to or greater than one percent asbestos is defined as a California hazardous waste.  A friable waste is one that can be reduced to a powder or dust under hand pressure when dry.  Non-friable asbestos-containing waste would not be considered hazardous.

California regulations require that hazardous waste be managed according to applicable regulations, which include: worker operational safety procedures as identified in Title 8 CCR; handling and storage and exposure requirements; transportation and disposal requirements under a uniform hazardous waste manifest; and documentation procedures.  In California, waste disposal facilities have been classified into three categories, Class I, Class II, and Class III.  A Class I disposal facility may accept federal and California hazardous waste.  Class II and III facilities are only permitted to accept non-hazardous waste at facility-specific acceptance threshold levels established by the RWQCB, the permitting agency.

In San Francisco, water generated from dewatering of construction sites is commonly discharged to the City’s combined storm drain/sewer system.  Discharges must be managed in accordance with the San Francisco Department of Public Works Batch Wastewater Discharge (BWWD) requirements.  Discharges to the combined storm drain/sewer system must comply with established threshold levels for chemical and physical parameters.

4.10.3 Health and Safety

Exposure to hazardous materials (or soils containing hazardous materials) could adversely affect construction workers and the public.  Exposure routes include inhalation, absorption through exposed skin area, and ingestion.  Federal and state regulations were developed to address worker exposure to safety and health hazards; these regulations are contained in 29 CFR on the federal level and in Title 8 CCR in California.  The Occupational Safety and Health Administration (OSHA) and California OSHA (CalOSHA) are the primary agencies responsible for enforcing these federal and state regulations.

4.10.4 Potential and Known Soil and Groundwater Contamination on Sites along Light CENTRAL SUBWAY Alignment

The Study Area constitutes an urban area with a history of commercial, industrial, and residential land uses dating back to before the turn of the century.  Urban areas with these types of historic land uses generally have various types of contaminants in the subsurface from disposal, storage, or spillage of hazardous materials.

This section identifies known subsurface soil and groundwater quality conditions within each segment of the Corridor. These available soil and groundwater quality data may be used to provide a general assessment of subsurface conditions.  The available sampling points are not uniformly distributed throughout the area and the number of sampling points is insufficient to provide a comprehensive characterization of the soils and groundwater quality of the Study Area.  Soil and groundwater sampling activities were not completed specifically for this project, but were undertaken by individual property owners in response to various regulatory requirements.  However, the available data can be used as an indicator of possible contamination that could be encountered in the Study Area.

In general, the primary contaminants of concern identified in the soils within the Study Area include metals, volatile organic compounds (VOCs), and total petroleum hydrocarbons (TPH).  Several samples contained metals and VOCs at concentrations greater than the regulatory limit threshold concentrations.  Soils containing serpentine fragments and asbestos were also identified in portions of the Study Area.  A summary of the analytical results is included in the technical reports referenced previously.

The primary contaminants identified in groundwater within the Study Area generally consist of metals (nickel and mercury), benzene, trichloroethylene (TCE), tetrachloroethylene (PCE), and oil and grease; these contaminants were identified in the groundwater samples at levels greater than the BWWD requirements established by San Francisco Department of Public Works.

There may be sources of contaminants from historic or current land uses or artificial fill in areas that have not been subject to subsurface investigations.  Land uses that could potentially affect the quality of underlying soil and groundwater include spillage or releases of hazardous materials; the land uses of special concern are those associated with industrial activities.  Typical contaminants that could be expected to be associated with industrial land uses are summarized in the detailed technical reports.

A portion of the Study Area is also within the boundary of Article 20; that area has been filled, since the turn of the century, with materials of various origins.  The quality of the fill is largely unknown, but generally has been found to contain hazardous substances that could affect construction workers and render the soil a hazardous waste, if excavated.  The fill areas generally coincide with the Article 20 boundary, which is shown as the 1851 High Tide Line on Figure 4-12.

Historic and current land uses in the Study Area include residential, commercial, and industrial land uses.  The land uses and known contamination are summarized from the detailed technical reports.  The technical studies previously referenced include tables which summarize the results of the regulatory file reviews, available chemical analytical data, and locations of underground storage tanks.  See Appendix G for maps depicting the sites of potential hazardous materials.

Central Subway Corridor - King Street to Chinatown

Past land uses along the Central Subway Corridor included a combination of residential, commercial, and industrial uses.  Along Third and Fourth Streets (between Townsend and Folsom Streets), land uses were primarily commercial and industrial;  land uses and activities in these areas included oil and gas use (specific business unknown), lithographics, bus garage, spray painting booth, machine shop, auto truck freight depot, paint spraying, printing warehouse, metal shop, auto body and greasing garage, blacksmith shop, and scrap metal facility.  A coal gasification plant (Citizens Gas Company), that operated between 1866 and 1886, was reportedly located near Townsend and Second Streets.  A second gas manufacturing facility (Pacific Gas Improvement Company) was reportedly located south of Townsend Street between Second and Third Streets and operated between the 1880s and early 1900s.  It is likely that waste products from these two plants were discharged to the Bay and may be present within the fill in this area.  Between Folsom and Sutter Streets, past land uses included gas and oil (of undermined form), printing and sign painting, an underground garage (which currently exists), retail stores, hotels, and offices.  North of Sutter Street, land uses were primarily commercial and residential.

Figure 4-12

General Vicinity Map of Study Area

Current land uses along Third and Fourth Streets (between Townsend and Folsom Streets) are primarily commercial (gas stations, parking, auto service and body, paint company) and residential.  Offices, parking garages, and the Moscone Convention Center are located between Folsom and Sutter Streets.  North of Sutter Street, current land uses consist of offices, retail stores, hotels, and apartments.  A number of vacant lots were observed during site reconnaissance activities in 2003; many of these lots appeared to have been subjected to random dumping of various materials, including trash, whereas others were in the process of being redeveloped.

The regulatory database searches and file reviews identified numerous sites along or in the proximity of the alignment where chemical compounds are likely present in soil and groundwater.  In general, the chemical compounds likely to be present in soil and groundwater along the Corridor are as follows:

· Petroleum hydrocarbon compounds (TPH as gasoline, diesel, and motor oil) and fuel-related VOCs, such as benzene, are likely to be present in the near-surface soil and groundwater, especially near leaking underground storage tank (LUST) and underground storage tank (UST) sites.

· Other VOCs, such as degreasers and thinners, may be present from former activities in the Study Area.

· According to the San Francisco DPH, groundwater in the northern portion of the Study Area is affected by a regional-scale chlorinated solvent plume.

· Polynuclear aromatic hydrocarbons (PAHs) associated with former coal gasification plants likely are present in the area south of Market Street, particularly in areas underlying fill bayward of the 1851 high tide line.  Dumping of slag on adjacent properties has been associated with the historical operation of several former coal gasification plants.  Previous investigations at plants located along The Embarcadero have revealed the presence of waste materials at depths ranging from approximately 28 to 40 feet below ground surface (bgs).

· Historical Sanborn maps indicated the locations of several electrical substations and transformers.  Polychlorinated biphenyl (PCB) compounds may be present in soil in those areas.

· Various metals are likely present in fill.  Lead has been reported at concentrations exceeding its hazardous waste threshold.  Arsenic may be present in soil along railroad tracks, such as the area just south of Townsend Street.  According to DPH, asbestos-containing material (ACM) and lead-impacted soil were detected during construction of the Chinese Playground in Chinatown.

Groundwater quality in the Downtown area of San Francisco generally is degraded due to the presence of solvents, petroleum hydrocarbon constituents, and other chemicals.  Due to the degraded nature of the groundwater, the California Regional Water Quality Control Board, San Francisco Bay Region (RWQCB), has approved closure for several LUST sites that are characterized by contaminant levels higher than those that are typically allowed for site closure.  Refer to the tables in the technical studies for a summary of available chemical analytical data for groundwater along the alignment. 

Depth to groundwater in the Study Area is highly variable and ranges from approximately 3 to 50 feet bgs.  The reported groundwater flow directions are inconsistent and, at several sites, have been shown to be different from the regional groundwater flow direction (generally towards San Francisco Bay).  The high variability in groundwater gauging data is attributed to variable topography and geology in the area, in combination with dewatering processes associated with construction projects and existing building foundations or basements.

North Beach Tunnel Construction Variant – Chinatown to Vicinity of Washington Square

The approximately 2000-foot extension for the North Beach Tunnel Construction Variant would be via Stockton Street and Columbus Avenue to a temporary construction shaft on Columbus Avenue near Washington Square in North Beach. Past land uses in this area included residential, commercial, and industrial.  Commercial uses identified included retail shops and hotels.  There were many industrial uses, including numerous factories, which manufactured various items, including food (e.g., ravioli, macaroni, sausage, tortillas, noodles, and candy), overalls, paste, cigars, and garments.  Other industrial and commercial facilities included machine shops, tin shops, photo shops, paint shops, drugstores, dyeing and cleaning shops, auto service shops, undertakers, plumbing shops, electrical shops, oil and gas facilities (of undetermined form), plating works, printing and sign painting, movie theaters, and stables.

Current land uses within the North Beach portion of the Study Area consist of a mixture of commercial and residential uses.  In general, the area west of Powell Street is dominated by residential uses, as is the area north of Broadway from the eastern boundary of the Study Area west to Stockton Street.  The remaining portions of the Study Area, are dominated by commercial facilities (e.g., retail shops, restaurants, and parking structures) and include apartments on the upper floors.  The dominantly commercial portions of the Study Area also include some high-density San Francisco Housing Authority residential complexes (e.g., on the southern side of Pacific Avenue).  Auto service shops were observed at the corner of Pacific Avenue and Powell Street and at the corner of Filbert Street and Grant Avenue.

Federal or California hazardous waste generators/facilities were identified in the North Beach Study Area, including those reported to have had a release of petroleum due to a leaking underground storage tank.  Numerous LUST sites, both open and closed, are located within the limited Study Area.  Chemical compounds that may be present in soil and groundwater along the North Beach Construction Variant may include, but not be limited to, petroleum hydrocarbon compounds and fuel-related volatile organic compounds (VOCs), such as benzene; other VOCs, such as degreasers and thinners; and various metals (likely present in fill).  At four LUST sites (766 Vallejo Street, 1625 Powell Street, 1636 Powell Street, and 1641 Powell Street), the regulatory database and review of DPH files indicated that subsurface soil and groundwater were impacted with fuel-related VOCs, total petroleum hydrocarbons (TPH) as gasoline, diesel, and motor oil.

Groundwater measurement data were available at the four LUST sites discussed above.  Data collected at 766 Vallejo Street in 1998 indicate groundwater at approximately 8 feet bgs.  At 1636 Powell Street, groundwater was encountered at 1 to 16 feet bgs.  At 1625 and 1641 Powell Street, groundwater was encountered at 4 to 18 feet bgs.

4.11 AIR QUALITY

4.11.1 Air Quality Standards

National Ambient Air Quality Standards (NAAQS) were established in 1970 by the federal Clean Air Act for airborne concentrations of six national criteria pollutants, including; ozone (O₃), carbon monoxide (CO), nitrogen dioxide (NO₂)_, sulfur dioxide (SO₂), lead (Pb), and particulate matter with a diameter of 10 microns or less (PM₁₀).  In July 1997, the US Environmental Protection Agency (EPA) promulgated new NAAQS for particulate matter with diameters less than or equal to 2.5 microns (PM_2.5).  The NAAQS for PM_2.5 are 15 micrograms per cubic meter (m/m³) and 65 m/m³ for the annual average and 24-hour periods, respectively.  In addition, the 1-hour ozone standard of 0.12 parts per million (ppm) was revoked on June 15, 2005 and was replaced by an 8-hour standard of 0.08 ppm.

The California Air Resources Board (CARB) has established State Ambient Air Quality Standards (SAAQS), many of which are more stringent than the corresponding NAAQS.  The 1988 California Clean Air Act, amended in 1992, sets standards for the six national criteria pollutants as well as for hydrogen sulfide, sulfates, and vinyl chloride, for which there are no corresponding NAAQS.  In May 2006, the CARB created a new 8-hour O₃ standard of 0.07 ppm.  The ambient air quality standards are designed to protect segments of the population most susceptible to the pollutants’ adverse effects, or sensitive receptors.  Sensitive receptors are considered the very young, the elderly, people weak from disease or illness, or persons doing heavy work or exercise.  National and state standards for these criteria pollutants are presented in Table 4-24.  The source of each criteria pollutant and the corresponding health effects are described below.

The Central Subway Project is located within the San Francisco Bay Area Air Basin which is composed of nine counties.  Air quality in the Bay Area Air Basin is regulated by the Bay Area Air Quality Management District (BAAQMD), which operates ambient air quality monitoring stations within the Bay Area.  CARB regulates mobile source emissions and is responsible for reviewing state-required documentation submitted by regional agencies such as the BAAQMD and for submitting federally-required documents to EPA.

4.11.2 AIR POLLUTANTS OF CONCERN

Smog or O₃ is formed in the atmosphere by complex chemical reactions between nitrogen oxides (NO_x) and reactive organic gases (ROG) in the presence of sunlight.  The main sources of the ozone precursors are combustion processes and the evaporation of solvents, paints and fuels.  Automobiles are the largest

TABLE 4-24

CALIFORNIA AND NATIONAL AMBIENT AIR QUALITY STANDARDS

Notes: ⁽¹⁾       SAAQS stands for State Ambient Air Quality Standards (California).  SAAQS for ozone, carbon monoxide, sulfur dioxide (1-hour and 24-hour), nitrogen dioxide, and respirable particulate matter are values that are not to be exceeded.  All other California standards shown are values not to equaled or exceeded.

                  ⁽²⁾       ppm = part per million by volume; m/m³ = micrograms per cubic meter; n/a = not applicable.

                  ⁽³⁾       NAAQS stands for National Ambient Air Quality Standards.  NAAQS, other than ozone and those based on annual averages, are not to be exceeded more than once a year.  The ozone standard is attained when the expected number of days per calendar year with maximum hourly average concentrations above the standard is equal to or less than one.

            ⁽⁴⁾     On October 17, 2006, the NAAQS for PM_2.5 was lowered to 35 m/m³ from 65 m/m³.

n/a = not applicable

Source:    California Air Resources Board, Ambient Air Quality Standards, September 2007.

single source of ozone precursors in the Bay Area.  Short-term exposure to ozone can irritate the eyes and cause shortness of breath.  Chronic exposure to high ozone levels can permanently damage lung tissue.

CO is a colorless, odorless gas, formed by incomplete combustion of fuels.  The single largest source of CO is motor vehicles.  When inhaled at high concentrations, CO combines with the hemoglobin in the blood and reduces the oxygen-carrying capacity of the blood.

NO₂ is a reddish-brown gas that is a by-product of the combustion process.  Automobiles and industrial processes are the main sources of NO₂.  Nitrogen dioxide is an ozone precursor and can increase the risk of acute and chronic respiratory disease, as well as reduce visibility.

SO₂ is a colorless acid gas with a strong odor.  It is produced by the combustion of sulfur-containing fuels, such as coal, oil and diesel.  Sulfur dioxide can irritate lung tissue and increase the risk of acute and chronic respiratory disease.

In the past, airborne lead was primarily caused by gasoline-powered automobile engines, but since leaded fuels have been phased out of the gasoline market, it is no longer as prevalent.  Lead can cause hematological (blood-related) effects, such as anemia (iron-deficient blood), and inhibition of enzymes involved in blood synthesis.  Ambient levels of lead in the Bay Area are well below the ambient standard and are expected to continue to decline.

PM₁₀ refers to particulate matter ten microns and less in size and encompasses many solid or liquid particles in the atmosphere, including smoke, dust aerosols and metallic oxides.  Motor vehicles are the single largest source of PM₁₀ in the Bay Area.  Other sources are combustion, construction, grading, demolition and agricultural activities.  Some particulate matter is naturally occurring, such as pollen.  Extended exposure to particulate matter can increase the risk of chronic respiratory disease.  PM₁₀ also includes PM_2.5 which is particulate matter with a diameter of less than 2.5 microns.  These particles have an even higher likelihood of entering the body and lungs due to its smaller size and may be more harmful to humans.

Most diesel-related particulate matter (about 90 percent) falls within the PM_2.5 subgroup.  Particulate matter from diesel-fueled vehicles and equipment is of special concern because this type of particulate matter is small enough to be respirable and has many chemicals adsorbed to the surface, including known or suspected mutagens (causing changes in genetic structure) and carcinogens (cancer causing).  Diesel emissions are complex mixtures containing thousands of organic and inorganic constituents. 

4.11.3 Meteorology and topography

The primary factors that determine air quality levels are the location of air pollutant sources and the amount of pollutants being emitted.  Meteorological and topographical conditions, however, are also important.  Atmospheric conditions such as wind speed, wind direction, and air temperature determine the movement and dispersal of air pollutants, as well as, the rate of photochemical reactions in the atmosphere.  Another important factor in California is the Pacific Ocean, which moderates temperatures and helps create consistent wind gradients.

The San Francisco Bay Area is characterized by complex terrain consisting of coastal mountain ranges, inland valleys, bays, and associated flatlands.  Consequently, the Bay Area is subject to a combination of climatic factors that result in low potential for accumulation of pollutants near the coast and high potential in sheltered inland valleys.  The Study Area is located in the western portion of the Bay Area.  Because of the relatively flat terrain and the close proximity to the bay, the Project is located in an area where the dispersal of pollutants is relatively good compared to inland sheltered valleys.

The marine air creates cool summers, mild winters and infrequent rainfall; it drives the cool daytime sea breeze and maintains comfortable humidities.  Temperatures in San Francisco average 58 degrees Fahrenheit annually, ranging from the mid-40s on winter mornings to the mid-70s on late summer afternoons.  Rainfall averages 20 inches per year and is confined primarily to the wet season from late October to early May.[114]  Exceedances of air quality standards occur primarily during meteorological conditions conducive to high pollution levels, such as cold, windless winter nights, or hot, sunny, summer afternoons.

4.11.4 Existing Air Quality and Regional Attainment Status

The BAAQMD takes primary responsibility for national and state standard attainment planning, implementation and enforcement in the Bay Area.  Air quality conditions in the Bay Area have improved since the BAAQMD was created in 1955.  Ambient concentrations of air pollutants and the number of days on which the region exceeded the air quality standards have decreased.

Existing levels of air quality in the Study Area can generally be inferred from ambient air quality measurements conducted by the BAAQMD at two of its San Francisco monitoring stations.  The Potrero Hill station at 10 Arkansas Street measures all criteria pollutants (except for lead), including regional pollution levels (O₃), as well as primary vehicular emissions levels near busy roadways (CO).  The station at the BAAQMD headquarters, 939 Ellis Street, monitors only carbon monoxide.  Table 4-25 summarizes five years of published data (2002 through 2006) from the monitoring stations.  The highest CO concentrations from either of the two monitoring stations are presented in Table 4-25.  Monitoring for lead, hydrogen sulfide, and vinyl chloride is not conducted in the Project vicinity.  During this five-year period, there were no violations of the one-hour or the eight-hour CO standards at either the Ellis Street or Arkansas Street monitoring station.  At the Arkansas Street monitoring station, the state PM₁₀ standard was violated on four days in 2002 and one day in both 2003 and 2004.  These high levels also resulted in exceedences of the state annual arithmetic mean standard.  In 2005 and 2006, there were no

TABLE 4-25

SAN FRANCISCO AIR POLLUTANT SUMMARY, 2002-2006

Notes:     ⁽¹⁾  Most of the data comes from the monitoring station located at 10 Arkansas Street in San Francisco.  The CO concentrations represent either the Arkansas Street Station or the Ellis Street Station depending on which location had the highest value.

                        ⁽²⁾State standard, not to be exceeded, except for Lead standard, which is not to be equaled or exceeded.

⁽³⁾The federal 1-hour standard listed in the table was revoked in June 2005.  Federal and state 8-hour standards were not in effect during the monitoring period analyzed until 2006.  On October 17, 2006, the NAAQS for PM_2.5 was lowered to 35 m/m³ from 65 m/m³.

                        ⁽⁴⁾ ppm = parts per million; mg/m³ = micrograms per cubic meter.

                        ⁽⁵⁾State and federal statistics differ due to different samplers being used.

                        ⁽⁶⁾  Samples typically taken every six days.

                Underlined values are in excess of applicable standards.  n/a = not available.

Source:    California Air Resources Board, Air Quality Data Summaries, 2002-2006; www.arb.ca.gov.

violations of the state PM₁₀ standard.  The state/federal PM_2.5 standard was violated four times in 2002.  The annual arithmetic mean in 2002 also exceeded the state standard.  All other monitored pollutants were below federal and state standards.

The federal Clean Air Act requires non-attainment and maintenance areas to prepare air quality plans that include strategies for attaining and maintaining the federal standards.  Regional air quality plans developed under the federal Clean Air Act are included in an overall program referred to as State Implementation Plans (SIPs).  The California Clean Air Act also requires plans for non-attainment areas (the state PM standards are exempt from these plans) that will specify strategies to attain state air quality standards.  Thus, an area may have two sets of air quality plans.

Regionally, the San Francisco Bay Area air basin is currently designated as a non-attainment area for ozone at both the federal and state level.  On April 15, 2004, the EPA classified the Bay Area as a marginal non-attainment area for the federal ozone eight-hour standard.  Marginal non-attainment areas must attain the national 8-hour ozone standard by June 15, 2007.  However, certain elements of EPA’s 8-hour ozone standard implementation rule are still undergoing legal challenge.  It is not currently anticipated that marginal non-attainment areas will be required to prepare attainment demonstrations for the 8-hour standard.  Other planning elements may be required.  The Bay Area plans to address all requirements of the national 8-hour ozone standard.  

The California Clean Air Act requires the BAAQMD to update its Clean Air Plan for meeting the state one-hour ozone standard every three years.  The BAAQMD, in association with Metropolitan Transportation Commission (MTC) and the Association of Bay Area Governments (ABAG), has prepared the Bay Area 2005 Ozone Strategy to meet this requirement.  It was approved on January 4, 2006.  The Bay Area is currently unclassified for the recent state 8-hour ozone standard that went into affect in May 2006.  However, CARB is currently considering changing the status to non-attainment.

An important component of the Bay Area Ozone Strategy is a set of control measures that would further reduce ozone precursor emissions from a wide range of sources.  In addition to stationary and area source control measures, measures for on- and off-road mobile sources and transportation are included.  Depending on the type of mobile source, the EPA and/or CARB are the only agencies authorized to adopt fuel and emission control system specifications.  As such, the BAAQMD can only reduce mobile source emissions by providing grants or incentives to encourage the use of cleaner vehicle and fuels.  The Bay Area Ozone Strategy measures encourage the retirement of older, more-polluting equipment and vehicles, introduction of new, less-polluting equipment, and operational changes such as reduced idling.

With respect to PM (PM₁₀ and PM_2.5) non-attainment for the state air quality standards, the California Legislature recognized that PM was relatively intractable and excluded it from the basic planning requirements.  The control measures of the Clean Air Plan will reduce PM emissions through measures to reduce vehicular traffic. 

The Bay Area Air Basin is in attainment or unclassified (i.e., available data does not support a designation of non-attainment or attainment) for all other federal and state ambient air quality standards.

4.11.5 Project Conformity

In addition to SIP and Air Quality Plan activities, federal agencies must also make a determination of conformity with the SIP before taking any action on a proposed project located in a non-attainment or maintenance area.  In 1993, EPA published the General Conformity Rule that indicates how federal agencies are to make such a determination.  A similar rule was created to specifically address conformity issues related to highway or transit projects that receive funding or approval from the Federal Highway Administration (FHWA) or the Federal Transit Administration (FTA).  In general, transportation projects must not cause or contribute to new violations of air quality standards, worsen existing violations or interfere with timely attainment of standards.  Project conformity is evaluated at both the local level (“hot spot” analysis) and the regional level.  At the regional level, one aspect of the conformity determination is to confirm that the proposed project is included in currently conforming regional transportation plans as fiscally constrained (i.e., the project would be funded through revenues projected to be reasonably available over the next 25 years).  Another aspect is to confirm that the proposed project is included in transportation improvement programs, which list projects and their specific funding sources.  This would also result in the proposed project being included in regional air quality analyses.  The local level analysis requirements in the 1993 rules focused on CO levels in areas designated as non-attainment or maintenance for CO.  In March 2006, procedures were adopted to include PM_2.5 and PM₁₀ non-attainment and maintenance areas.

The Central Subway Project is located in a maintenance area for CO and as a result must have a local CO analysis conducted.  The area is currently unclassified for the federal 24-hour standard for both PM₁₀ and PM_2.5.  It is also in attainment for the annual PM_2.5 standard.  The EPA is required to designate attainment status for the newer 24-hour PM_2.5 standard by December 2009.  As a result, a hot spot analysis for particulate mater is not currently required for the Central Subway Project.

For the Bay Area, MTC adopted the conformity analysis for the Final Transportation 2030 Plan (RTP) and the 2005 Transportation Improvement Program (TIP) in February 2005.  The Third Street Light Rail Project Phase 2 Central Subway is included in both these documents as part of the financially constrained Tier 1 plan.  As a result, the Central Subway Project was included in the conformity analysis for these plans.  Project conformity of the Central Subway Project is further discussed in Section 5.11.

4.11.6 EXISTING POLLUTANT SOURCES

Pollutants are emitted by a variety of stationary, area and mobile sources.  Stationary sources are identified as utility, industrial, institutional, and commercial facilities operating at fixed locations.  Area sources are activities that individually emit relatively small quantities of air pollutants, but which cumulatively may emit a large amount of emissions.  Examples are gasoline service stations, consumer use of solvents, and fireplace use. 

The greatest sources of emissions in the Study Area are mobile sources.  Mobile sources are considered to be on-road vehicles such as cars and trucks, airplanes, trains, and off-road vehicles such as diesel-powered construction equipment.

The estimated emissions associated with motor vehicles in the Study Area in 2006 are presented in Table 4-26.  For a sense of magnitude, motor vehicle emissions in the Study Area account for approximately one to eight percent of San Francisco County’s overall total for pollutant emissions from all sources, depending on the pollutant.[115]  CO accounts for the highest percentage of motor vehicle emissions while particulate matter is the lowest.

TABLE 4-26

ESTIMATED 2006 MOTOR VEHICLE EMISSIONS IN THE STUDY AREA

(in pounds/day)

Note:  PM₁₀ includes PM_2.5

Source:  PB/Wong, 2007

one to eight percent of San Francisco County’s overall total for pollutant emissions from all sources, depending on the pollutant.[116]  CO accounts for the highest percentage of motor vehicle emissions while particulate matter is the lowest.

4.11.7 Sensitive Receptors

Air quality standards are set at pollutant levels considered to be safe for the public.  Of most concern are localized pollutant (CO and PM) impacts because these impacts are greater when members of the public are closer to the source of the emissions.  In general, air pollution is a concern wherever the public has access.  In the proposed Study Area, this could include locations such as sidewalks, boarding platforms, etc.  However, it is unlikely that a member of the public would be at any of these locations for a long period of time and would not have long-term exposure to pollutants generated in the area.  Particular attention is paid to locations where people who are more susceptible to respiratory infections and other air quality-related health problems are more likely to spend time.  These locations are termed sensitive receptors.  Land uses such as playgrounds and parks, schools, hospitals, clinics and health centers, and community centers are used by people who could be susceptible to the results of poor air quality.  Schools, hospitals and convalescence homes are relatively sensitive to poor air quality because of the people who frequent these locations (see Sections 4.1.3 and 4.3.1).  Residential areas are considered sensitive to poor air quality because people in residential areas are often home for extended periods.  Recreational land uses are moderately sensitive to air pollution, because vigorous exercise associated with recreation places a high demand on the human respiratory function.

School playgrounds and parks along the Project corridor are shown on Figure 4-4 and discussed in Section 4.3.3.  Sensitive receptors of particular interest for air quality include:

· Yerba Buena Center of the Arts at Third and Mission Streets;

· Union Square along Stockton Street;

· Gordon Lau Elementary School playground at Washington Street;

· Willie “Woo Woo” Wong Playground at Sacramento Street;

· Washington Square at Columbus Avenue and Union Street

4.11.8 Climate Change/Greenhouse Gas Emissions

At one time, all climate change occurred naturally.  However, now through human activity such as fossil fuel burning, deforestation, and growing population, the mixture of gases in the Earth’s atmosphere is being changed.  Certain gases are considered “greenhouse gases” because they absorb infrared radiation and trap the heat in the atmosphere thereby contributing to global warming.  Greenhouse gases include carbon dioxide (CO₂), methane, nitrous oxide, ozone, and water vapor.  Some of the gases occur naturally, while others are exclusively human-made.  The majority of human-made gases are from burning fossil fuels and include CO₂ and methane. 

California, despite its many environmental regulations, is still one of the largest producers of greenhouse gases.  State and local governments and agencies are becoming more active in the climate change issue. 

In the Bay Area, fuel consumption from transportation (on-road motor vehicles, off-road mobile sources, and aircraft) account for more than fifty percent of greenhouse gases generated in the Bay Area.  According to the BAAQMD, the Bay Area generates over 85 million tons of greenhouse gases and the City and County of San Francisco generates 6.7 million tons.[117]

In 2002, the San Francisco Board of Supervisors passed the Greenhouse Gas Emissions Reduction Resolution, committing the City and County of San Francisco to a greenhouse gas emission reduction goal of 20 percent below 1990 levels by the year 2012.  In September 2004, San Francisco released its Climate Action Plan, which provides an inventory and reduction target of greenhouse gas emissions.  The Plan also contains actions and implementation strategies to reduce greenhouse gas emissions from the transportation and solid waste sectors and through energy efficiency and renewable energy programs.

On June 1, 2005, Governor Schwarzenegger signed Executive Order S-3-05 establishing climate change emission reductions targets for the State of California.  The greenhouse gas reduction targets are as follows:  reduce emissions to 2000 levels by 2010, reduce emissions to 1990 levels by 2020, and reduce emissions to 80 percent below 1990 levels by 2050.  In addition, Governor Schwarzenegger signed AB 32 (known as the California Global Warming Solutions Act of 2006) on September 27, 2006 to create a comprehensive statewide program to reduce greenhouse gas emissions.  One of the requirements is that on or before June 30, 2007 CARB is required to publish a list of discrete greenhouse gas emission reduction measures that can be implemented.

4.12 NOISE AND VIBRATION

4.12.1 Noise and Vibration Measures

The following are brief descriptions of the measures used to characterize community noise and vibration in the Corridor.

A-Weighted Sound Level

Sound is measured using microphones that respond accurately to all audible frequencies.  The human hearing system does not respond equally well to all frequencies.  Low frequency sounds below about 400 Hz are progressively and severely attenuated, as are high frequencies above 10,000 Hz.[118]  To approximate the way humans interpret sound, a filter circuit with frequency characteristics similar to the human hearing system is built into sound measurement equipment.  Measurements with this filter enacted are referred to as "A-weighted sound levels", expressed in dBA.  Community noise is almost always characterized in terms of A-weighted levels. 

Equivalent Sound Level (Leq)

Leq is a measure of sound energy over a period of time.  It is referred to as the equivalent sound level because it is equivalent to the level of a steady sound which, over a referenced duration and location, has the same A-weighted sound energy as the fluctuating sound.  Leq's for periods of one hour, during daytime or nighttime hours and 24 hours are commonly used in environmental assessments.  Because Leq is a measure of the total sound energy, any new community noise source will cause Leq to increase.  To estimate how the Third Street Light Rail Project would increase Leq, it is necessary to know the existing Leq and add in the sound energy that would be created by light rail operations.  The more train operations and the longer and faster the trains, the more sound energy is added to the existing Leq.

Day-Night Sound Level (Ldn)

Ldn, also abbreviated DNL, is a 24-hour Leq, but with a 10 dB penalty assessed to noise events occurring at night.  Nighttime is defined as 10 p.m. to 7 a.m.  The effect of this penalty is that, in the calculation of Ldn, any event during nighttime hours is equivalent to ten events during the daytime hours.  This strongly weights Ldn toward nighttime noise to reflect most people being more easily annoyed by noise during the nighttime hours when both background noise is lower and most people are sleeping.  Ldn is often used to characterize community noise when assessing community noise impacts.  Almost all urban and suburban

neighborhoods are in the range of Ldn 50 to 70.  An Ldn of 70 dBA represents a relatively noisy area, which might be found near a freeway or a busy surface street.  Residential neighborhoods that are not near major sound sources are usually in the range of Ldn 50 to 60 dBA.  If there is a freeway or moderately busy arterial nearby, or any substantial nighttime noise, Ldn is usually in the range of 60 to 65 dBA.

Vibration Velocity

Vibration velocity is the basic measure of ground-borne vibration.  It is a measure of the rate at which particles in the ground are oscillating relative to the equilibrium point.

Vibration Velocity Level

It is generally accepted that, over the frequency range important for ground-borne vibration from transit systems, human response to vibration is best correlated to the root-mean square (rms) vibration velocity.  In this report, rms vibration velocity is always expressed as decibels relative to 1 micro-inch per second.  A one second rms time constant is assumed.  The units are abbreviated as VdB to avoid any confusion with noise decibels. 

Following are typical responses to different levels of building vibration caused by rail transit operations:

· Less than 65 VdB: The building vibration is imperceptible or just barely perceptible.

· 70 to 75 VdB: The vibration may be noticeable, but most people will not consider it intrusive.

· 80 to 85 VdB:  The vibration is very noticeable and many people may find the vibration to be unacceptable for residential uses.

· Greater than 85 VdB:  If the vibration lasts for more than a couple of seconds, it could make some tasks, such as working at a computer screen, difficult.

Peak Particle Velocity (ppv)

Specifications for allowable levels of vibration from blasting, pile driving and other construction processes with the potential of causing building damage are almost always expressed in terms of peak particle velocity since this is thought to be well correlated with maximum stresses in buildings.  Peak particle velocity is the instantaneous positive or negative peak in the vibration signal.  The peak may occur for only a small fraction of a second even when the vibration event is several seconds long.  As discussed above, it is generally accepted that human response to vibration is better correlated to rms velocity than peak particle velocity.  Peak particle velocity is normally expressed in units of inches per second.  Limits to avoid cosmetic building damage from construction vibration are usually in the range of 0.9 to 2 inches per second.

4.12.2 Noise and Vibration Standards

Construction Noise

Most large construction projects have the potential of being sufficiently noisy to be intrusive to adjacent communities, particularly when construction must be performed at night.  However, construction noise is temporary in nature and usually has no permanent effects.  Although no standardized criteria have been developed for assessing construction noise impact, the FTA guidance manual “Transit Noise and Vibration Impact Assessment” includes guidelines to use when local ordinances or other standards are not applicable.  The FTA guidelines are summarized below in Table 4-27.

TABLE 4-27

FTA GUIDELINES FOR IMPACT FROM CONSTRUCTION NOISE

             Notes:         ⁽¹⁾In urban areas with very high ambient noise levels (Ldn>65 dBA), Ldn from construction should not exceed existing ambient plus 10 dB.

                                ⁽²⁾Twenty-four hour Leq, not Ldn.

Source:     FTA, 2006

Since the proposed Central Subway project would be entirely within the City and County of San Francisco, all construction would be subject to San Francisco regulations.  Article 29, Regulation of Noise, of the San Francisco Police Code includes specific limits on noise from construction.  The basic requirements are:

· Maximum noise level from any piece of powered construction equipment is limited to 80 dBA at 100 ft.  This translates to 86 dBA at 50 feet; 

· Impact tools are exempted, although such equipment must be equipped with effective mufflers and shields (the noise control equipment on impact tools must be as recommended by the manufacturer and approved by the Director of Public Works); and

· Construction activity is prohibited between 8 p.m. and 7 a.m. if it causes noise that exceeds the ambient noise plus 5 dBA.  In many cases, this condition acts to prohibit nighttime construction unless the City grants a variance.

Performing construction in compliance with the City regulations would ensure that construction noise would be below the FTA guidelines.

Construction Vibration

Ground-borne noise, is vibration that is transmitted through the soil to a building where it causes the elements of the building to radiate noise.   During construction potential sources of ground-borne noise would be the tunnel boring machine, muck trains removing the tunnel spoils, and other underground activities.  It is proposed that 5 dBA be added to the FTA ground-borne noise criteria presented in Table 4-19 as the basis for a noise level limit  during construction, for protection of adjacent historic architectural buildings. 

Damage Risk Vibration Criteria

Vibration, as it is related to building damage, is generally assessed in terms of peak particle velocity (PPV).  PPV is defined as the maximum instantaneous positive or negative peak of the vibration signal in any of three directions, vertical, horizontal or lateral (x, y or z).  PPV is the appropriate metric for evaluating the potential of building damage and is often used in monitoring blasting and construction vibration since it relates to the stresses that are experienced by buildings.

Peak particle velocity is typically a factor of 1.7 to 6.0 times greater than root mean square (rms) vibration velocity.  Root mean square vibration velocity is used to assess potential human annoyance from vibration.  A factor of 4.0 has been used to relate the building damage criteria used in this report to approximate rms vibration velocity levels, which are used by FTA to define the vibration generated by LRT operations.

The severity of vibration-induced structural damage can be categorized as major or minor.  Major damage caused by high levels of ground vibration would include serious structural damage, glass breakage, and serious plaster cracking possibly accompanied by falling plaster.  For lower levels of vibration, minor damage, which would include fine plaster cracking and the reopening or widening of old cracks, may be observed.

The U.S. Bureau of Mines has identified ground vibration levels that may produce damage in residential structures.  By averaging the data of many investigators, the Bureau has found that ground vibration with peak velocities (PPV) on the order of 7.6 inches/second (in/sec) may cause major damage in residential structures, whereas a PPV near 5.4 in/sec may cause minor damage.  The Bureau therefore suggests that a safe limit for structural damage would be a PPV of 2.0 in/sec, as measured in any of the three directions (x, y or z) in the ground adjacent to a structure.  This limit is based on the probability that 95 percent of the structures exposed to this level of vibration would not have any structural damage. 

A widely accepted criterion is that below 0.5 inch per second peak velocity there is no risk of minor damage to non-historic residential and office buildings.  This criterion level is far below the threshold of risk of major structural damage, but it makes some allowance for buildings of all types and for the triggering effect of vibration on stress concentrations that may already be present in the affected buildings.

In the case of old and historic buildings, the situation is not as clear.  The level cited as safe from minor damage (0.2 inch per second peak velocity) is probably adequate for historic buildings as a simple guideline level, but it cannot account for long-term fatigue damage that may occur after many years of vibration.  Such fatigue damage has been observed in very old structures, e.g. European cathedrals erected in the Middle Ages.  In view of this uncertainty, a peak ground vibration velocity of 0.12 in/sec based on German standard, DIN 4150 is recommended as a conservative "minor damage" criterion to be applied in the assessment for buildings of historic value.

The Federal Transit Administration, in their Transit Noise and Vibration Impact Assessment,  2006 report recommends applying a vibration damage threshold criterion of PPV 0.20 in/sec for fragile buildings, or PPV 0.12 in/sec for extremely fragile historic buildings.

Based on the research to date, as discussed above, the following criteria levels, presented in Table 4-28 would be used to judge the potential risk of damage to historic buildings or cultural resource structures during construction of the project.  These levels are significantly lower than the FTA vibration criteria of 72 to 75 VdB for LRT operations and are also lower than the maximum vibration levels projected from the LRT operations at any structure along the alignment.

Operation Noise

The operation of light rail vehicles along at-grade track presents the greatest potential for noise impact.  Impact from operational noise for this project is based on the FTA criteria as defined in the guidance manual “Transit Noise and Vibration Impact Assessment.”  The FTA noise impact criteria are founded on well-documented research on community reaction to noise.  The criteria are based on the change in

Table 4-28

Damage Risk Vibration Criteria

            Note: Peak particle velocity is assumed to be four times greater than root mean square (rms) vibration velocity.

noise exposure using a sliding scale.  Although the FTA criteria allow more transit noise in neighborhoods with high levels of existing noise, they also reduce the amount that total noise exposure can be increased in neighborhoods with high levels of existing noise.

The FTA Noise Impact Criteria group noise sensitive land uses into the following three categories:

Category 1:       Buildings or parks where quiet is an essential element of their purpose.

Category 2:       Residences and buildings where people normally sleep.  This includes residences, hospitals, and hotels where nighttime sensitivity is assumed to be of utmost importance.

Category 3:       Institutional land uses with primarily daytime and evening use.  This category includes schools, libraries, and churches. 

Ldn is used to characterize noise exposure for residential areas (Category 2).  For other noise sensitive land uses, such as parks and school buildings (Categories 1 and 3), the maximum 1-hour Leq during the facility’s operating period is used.

There are two levels of impact included in the FTA criteria.  The interpretation of these two levels of impact is summarized below:

· Severe:  Severe noise impacts are considered "significant" as this term is used in NEPA and implementing regulations.  Noise mitigation will normally be specified for severe impact areas unless there is no practical method of mitigating the noise.

· Moderate Impact:  In this range of noise impact, other project-specific factors must be considered to determine the magnitude of the impact and the need for mitigation.  These other factors can include the predicted increase over existing noise levels, the types, and number of noise-sensitive land uses

affected, existing outdoor-indoor sound insulation, and the cost effectiveness of mitigating noise to more acceptable levels.  Although other factors should be considered when designing mitigation for Moderate Impact, it is assumed by FTA that some sort of mitigation will be specified for most Moderate Impacts.

The noise impact criteria are summarized in Table 4-29.  The first column shows the existing noise exposure and the remaining columns show the additional noise exposure caused by the transit project that is necessary for the two levels of impact.  The future noise exposure would be the combination of the existing noise exposure, the additional noise exposure caused by the transit project, and the small reduction in noise because of fewer diesel buses and a slightly lower volume of vehicular traffic in the Third Street Corridor.  The impact thresholds given in Table 4-29 have been rounded off to the nearest decibel, which is appropriate given that a one decibel difference in noise level is barely perceptible for humans.  However, in performing the noise impact assessment, the projections and the impact thresholds are not rounded off until the final step.

Operation Vibration

Ground-borne vibration from light rail operations may be perceived by building occupants in the following manners:  1) perceptible vibration of floors and walls; 2) rattling of windows; 3) rattling of items hanging on walls, or rattling of dishes and bric-a-brac on shelves; or 4) as a low-frequency rumbling noise.  The rumbling noise is caused by sound radiated from vibrating room surfaces and is referred to as ground-borne noise.  Table 4-30 shows the limits on ground-borne vibration and ground-borne noise that are applicable to this Project.  Although there is only limited information on how occupants respond to building vibration, the limits in Table 4-30 are based on available research and on the experience of rail transit systems and their vibration complaints.

International standards have been developed for the effects of vibration on people in buildings with ratings related to annoyance and interference with activities based on frequency distribution of acceptable vibrations.  These criteria have been supplemented by industry standards for vibration-sensitive equipment.  Both sets of criteria are expressed in terms of one-third octave band velocity spectra, with transient events like train passbys described in terms of the maximum rms vibration velocity level with a one-second averaging time.  The measurement point is specified as the floor of the receiving building at the location of the prescribed activity.

The vibration impact criteria are shown in Figure 4-13 where the international standard curves and the industry standards are plotted on the same figure.  Interpretations of the various levels are presented in

Table 4-29

FTA Noise Impact Criteria

             Note:          ⁽¹⁾Ldn is used for land uses where nighttime sensitivity is a factor; maximum 1-hour Leq is used for land use involving only daytime activities.

Category Definitions:

                   Cat 1:    Buildings or parks where quiet is an essential element of their purpose.

                   Cat 2:    Residences and buildings where people normally sleep.  This includes residences, hospitals, and hotels where nighttime            sensitivity is assumed to be of utmost importance.

                   Cat 3:    Institutional land uses with primarily daytime and evening use.  This category includes schools, libraries, and churches.

Source:     FTA, 2006.

Table 4-30

Ground-Borne Vibration (GBV) and GROUND-BORNE Noise (GBN)

Impact CriteriA

Notes:

1. “Frequent Events” is defined as more than 70 vibration events of the same source per say.  Most rapid transit projects fall into this category.

2. “Occasional Events” is defined as between 30 and 70 vibration events of the same source per day.  Most commuter trunk lines have operations with this many events.

3. “Infrequent Events” is defined as fewer than 30 vibration events of the same kind per day.  This category includes most commuter rail branch lines.

4. This criterion limit is based on levels that are acceptable for most moderately sensitive equipment such as optical microscopes.  Vibration sensitive manufacturing or research will require detailed evaluation to define the acceptable vibration levels.  Ensuring lower vibration levels in a building often requires special design of the HVAC systems and stiffened floors.

Source:     FTA, 2006.

Table 4-31.  One-third octave band levels that exceed a particular criterion curve indicate the need for mitigation and the frequency range within which the treatment needs to be effective. 

The residential limits presented in Figure 4-13 has been used on a number of previous Muni projects.  The vibration is considered acceptable as long as no part of the 1/3 octave band spectrum is exceeded. 

4.12.3 Existing Noise Conditions at Sensitive Receptors

Existing noise exposure at sensitive receptors along the Corridor was documented through noise monitoring and analysis.  Noise monitoring was performed at a total of 15 locations (6 of the samples used were taken along the Central Subway in 1997) throughout the corridor that are representative of the noise sensitive receptors in the corridor.  Measurements taken in 1997 remain representative at noise levels at these locations when compared with nearby measurements taken in 2007.  As discussed below, the monitoring showed existing noise exposure to be relatively high in the Corridor due to existing traffic on Third Street, Fourth Street, Stockton Street, and other heavily traveled arterials.

Figure 4-13

Detailed Ground-Borne Vibration Criteria

Source:  FTA 2006

Table 4-31

Interpretation of Detailed Vibration Analysis Criteria

      ¹ As measured in 1/3-octave bands of frequency over the frequency range 8 to 80 Hz.

  Source:  FTA 2006

Existing noise is an important element of the noise impact assessment as the FTA criteria for noise impact from transit operations are based on the levels of existing noise.  Since it is not possible to measure ambient noise at every noise sensitive receptor in the Corridor, the noise monitoring results are generalized so that a limited number of measurements can be used to estimate existing noise exposure at all sensitive receptors in the Corridor.  The generalization process is relatively straightforward since traffic is the major existing noise source and the traffic volumes are similar in large sections of the Corridor.

The following sections discuss the approach and results of the noise monitoring program.  The generalized noise levels used for the evaluation of noise impact are also described.

Noise Monitoring Program

Noise monitoring was performed at a total of 15 locations using two approaches:

1.   Long-Term Monitoring:  Continuous noise monitoring over a 24-hour weekday period was performed at a total of five locations using unattended monitors.  The monitors were programmed to provide several measures of noise exposure for each hour and for the entire 24-hour period. 

2.   Short-Term Monitoring:  The 24-hour monitoring was supplemented with short-term noise measurements performed at an additional ten locations throughout the corridor.  Traffic counts were made at the same time as the measurements to provide a means of correlating traffic volumes with ambient noise levels.  The short-term measurements were all 30 minutes long on a weekday between 8 a.m. and 6 p.m.

The monitoring sites were selected to be representative of noise sensitive land uses in the Corridor, typically single- or multi-family residences, churches, or parks.  Figures 4-14 and 4-15 show the general locations of the monitoring sites for the different alternatives.  The measurement microphones were positioned to characterize the exposure of the site to the dominant noise source in the area, which was almost always vehicular traffic on busy arterials.  The measurement microphones were located at the approximate set-back lines of residences from the road and were positioned to avoid acoustic shielding by buildings, landscaping, walls, fences, or other obstructions.

The results of the noise monitoring are summarized in Table 4-32 in terms of Ldn and peak hour Leq during daytime and nighttime hours.  Each short-term noise measurement is compared to the closest 24-hour measurement site at the same hour of the day.  The short-term noise levels are then adjusted relative to the 24-hour levels in order to develop a peak Leq and Ldn for each of the short-term measurement locations.

Traffic counts were performed at representative receiver locations where short-term ambient noise measurements were conducted.  Table 4-33 shows the results of the traffic counts at these sites in the traffic count column.  Projections of noise levels developed using a simplified version of the approved FHWA model for traffic noise and traffic counts are also presented in Table 4-33.  Measurement Site N6, the measurement site near the houseboat community in the China Basin channel west of Fourth Street, is not shown in Table 4-33 because a single source of traffic noise was not dominant at this location.  Noise at Site N6 was a composite of traffic noise from a number of sources including the I-280 freeway, Fourth Street, and Channel Street. 

The projected levels of traffic noise in Table 4-32 are within 1 dBA of the measured level at six of the sites and within 3 dBA of the measured level at one site, and 5 dBA at one site.  The general trend is that the projections are higher than the measured levels.  This is a reasonably good agreement given that the FHWA model is designed for freely flowing traffic at speeds above 30 mph, while the traffic in the measurement area was typically stop and start, with the speed being highly variable.  The comparison of the measurements and the projections using the simplified FHWA model validate use of the model to

Figure 4-14:  Noise and Vibration Measurement Positions

(Enhanced 1998 EIS/EIR Alignments Sites N1 - N6)

Figure 4-15:  Noise and Vibration Measurement Positions  

(Fourth/Stockton Alignment - Sites 1 - 3, and Sites A - F)

Table 4-32

Summary of Noise Monitoring Results

NA – These sites do not have sleep activity.  Ldn existing noise levels are not applicable at these sites.

Each 15-minute noise measurement is compared to the closest 24-hour measurement site at the same hour of the day.  The 15-minute noise levels are then adjusted relative to the 24-hour levels in order to develop a peak Leq and Ldn for each of the 15-minute measurement locations.

Source:  PB/Wong 2006

Table 4-33

Traffic Counts During Short-Term Measurements

Source:  PB/Wong 2006

determine whether the change in the traffic patterns resulting from this project would cause any noise impacts.

4.12.4 Existing Vibration Characteristics

Ambient Vibration

Existing sources of ground-borne vibration in the Study Area include: vehicular traffic on surface streets, particularly heavy trucks and buses; the BART and Muni subway lines operating under Market Street; vehicular traffic on the Hwy 101 and I-280; Caltrain operations; and the Muni Metro Extension to the Caltrain Terminal at Fourth and King Streets.  All of these sources can cause perceptible ground-borne vibration at distances up to about 30 meters (100 feet) from the source, although the vibration from street and freeway traffic is not generally perceptible unless there are some sort of irregularities in the roadway surface such as potholes.  As a result, even though there are a number of sources of ground-borne vibration in the Corridor, ambient vibration is not expected to exceed the threshold of human perception except in localized areas near these sources. 

Although ambient vibration is rarely an issue, a limited number of measurements are usually performed to document existing vibrations levels.  Even when existing ground-borne vibration is not expected to be perceptible, documenting the existing levels of ground-borne vibration can help identify whether the local geology is prone to vibration problems. 

Short-term vibration measurements of 20 minutes were carried out near the corner of Stockton and Sacramento Streets (noise monitoring site N2) as a representative location where residential uses would be affected by ambient vibration.  The ambient vibration measurements were made with high-sensitivity accelerometers mounted in the vertical direction on flat, paved surfaces and set back from the street at the nearest residential building facade.  The acceleration signal was recorded using a digital audio tape (DAT) recorder.  The tape recording was subsequently analyzed in the laboratory to determine average and maximum vibration levels.

The results of the ambient vibration measurements are summarized in Table 4-34.  The highest observed vibration levels were caused by buses and heavy trucks.  As a point of reference, the threshold of human perception is around 65 VdB.  The average vibration levels, which are around 50 VdB, are well below the threshold of human perception.  Even the maximum levels during the 20-minute measurement periods were below the threshold of human perception.  The measurements confirm that existing ground-borne vibration in the Corridor is not sufficient to be intrusive.

Table 4-34

Ambient Vibration Monitoring Results

                             Notes:      ⁽¹⁾             Energy average over 20-minute measurement period.

                                                                        ⁽²⁾             Maximum vibration velocity level with 1-second rms time constant.

Vibration Propagation

In addition to the measurements of ambient vibration, a special test was performed to characterize vibration propagation in the Study Area.  The vibration propagation test basically consists of using a weight dropped onto a load cell to cause a ground-vibration pulse.  The impact force of the dropped weight is measured with the load cell and accelerometers are used to measure the vibration pulse at distances from 25 to 200 feet from the load cell.  These measurements are a key component of the ground-borne vibration projection procedure since they eliminate the need to approximate how a particular set of geologic conditions will affect levels of ground-borne vibration.

The quantity used to characterize vibration propagation is transfer mobility, which describes the ground's response to a vibration input at a given distance.  The goal is to determine the difference between the transfer mobility measured at a reference site where trains are operating and the transfer mobility at a new site where similar trains are proposed.  This difference is then used to adjust train vibration data from the reference site to the conditions of the new site. 

The alignment was divided into three regions with similar soil types and layering.  Transfer mobility data were collected at three monitoring well boreholes:  Pagoda Alley (Chinatown), Jessie and Third Streets, and Welsh and Fourth Streets.  Transfer mobility data from these three boreholes were taken as representative for their specific alignment region as shown in Table 4-35.

Table 4-35

Vibration Propagation Test Locations

Groundbourne Noise and Vibration Study Task 1.02-07, Revision 1, February 27, 2004

Source:  PB/Wong

Additional surface vibration-propagation testing was performed at two locations:  Freelon Alley (next to 570 Fourth Street), and Varney Place.  All measurement locations are shown in Figure 4-14.

Details of the vibration propagation tests are contained in the Noise and Vibration Technical Report.  The vibration propagation curves for the four sites were similar even though the sites were distributed along the Corridor.  None of the sites displayed any evidence of unusually efficient vibration propagation.  For this preliminary analysis, the results at the four test sites were combined into one curve that was used to characterize all of the proposed locations of at-grade track in the Corridor.  At the sites where vibration impacts have been predicted (Section 5.12), detailed propagation testing would be performed during the final design phase of the Central Subway project to improve the estimates of vibration propagation and to design specific improvement measures into track design.

[43]   SFCD = +8.616 feet National Geodetic Vertical Datum.

[44]   ICF Kaiser.  Preliminary Plans and Profile, Central Subway Alignment, Stockton/Third/Fourth Streets.  1 October, 1996.

[45]   Schlocker, J.  Geology of the San Francisco North Quadrangle, California, U.S. Geological Survey, Professional Paper, 782.  1974.

[46]   Ibid.

[47]   Bonilla, M.  Preliminary Geologic Map of the San Francisco South Quadrangle and Part of the Hunters Point Quadrangle, California, U.S. Geological Survey Miscellaneous Field Studies, Map MF-311.  1971.

[48]   ICF Kaiser.  Preliminary Plans and Profile, Central Subway Alignment, Stockton/Third/Fourth Streets.  October 1, 1996.

[49]   Geotechnical Consultants, Inc.  Geotechnical Report for MUNI Metro East Facility, LRT Extension, San Francisco, California.  11 August, 1993.

[50]   Phillips, S.P., S. Hamlin, and E. Yates.  Geohydrology, Water Quality, and Estimation of Groundwater Recharge in San Francisco, California, 1987-1992, U.S. Geological Survey Water Resources Investigations, Report 13-4019.  1993.

[51]   Schlocker, J.  Geology of the San Francisco North Quadrangle, California, U.S. Geological Survey, Professional Paper, 782.  1974.

[52]   Ibid.

[53]   Ibid.

[54]   Lee & Praszker.  Geotechnical Report, Idealized Subsurface Profiles, San Francisco Museum of Modern Art, San Francisco, California.  14 August, 1990.

[55]   Schlocker, J.  Geology of the San Francisco North Quadrangle, California, U.S. Geological Survey, Professional Paper 782.  1974.

[56]   Ibid.

[57]   Goldman, H., Editor.  Geologic and Engineering Aspects of San Francisco Bay Fill, California Department of Conservation, Division of Mines and Geology, Special Report 97.   1969.

[58]   Ibid.

[59]   Goldman, H., Editor.  Geologic and Engineering Aspects of San Francisco Bay Fill, California Department of Conservation, Division of Mines and Geology, Special Report 97.  1969.

[60]   Lee & Praszker.  Geotechnical Report, Idealized Subsurface Profiles, San Francisco Museum of Modern Art, San Francisco, California.  14 August, 1990.

[61]   Schlocker, J.  Geology of the San Francisco North Quadrangle, California, U.S. Geological Survey, Professional Paper 782.  1974

[62]   Ibid.

[63]   Perkins, J. and J. Boatwright.  The San Francisco Bay Area - On Shaky Ground, Association of Bay Area Governments.  April, 1995.

[64]   Ibid.

[65]   California Department of Conservation, Division of Mines and Geology.  California Fault Parameters, San Andreas Fault Zone.  1996.

[66]   California Department of Conservation, Division of Mines and Geology.  California Fault Parameters, San Francisco Bay Area Faults.  1996.

[67]   Peterson, M.  California Department of Conservation, Division of Mines and Geology.  Personal communication with Baseline Environmental Consulting. 22 November, 1996.

[68]   U.S. Geological Survey.  Working Group on California Earthquake Probabilities.  Probabilities of Large Earthquakes in the San Francisco Bay Region: 2002-2031, California,, Open File Report 03-214.  2003.

[69]   Bray, J. and Kelson, K.  Observations of Surface Fault Rupture from the 1906 Earthquake in the Context of Current Practice, Earthquake Spectra, Special Issue II, Vol. 22.  April 2006.

[70]   Uniform Building Code.  International Conference of Building Officials.  1994

[71]   Ibid.

[72]   Ibid.

[73]   Sydnor, R.  California Department of Conservation, Division of Mines and Geology.  Personal communications with Baseline Environmental Consulting.  21 November, 1996.

[74]   Perkins, J. and J. Boatwright.  The San Francisco Bay Area - On Shaky Ground, Association of Bay Area Governments.  April, 1995.

[75]   Ibid.

[76]   Ibid.

[77]   Association of Bay Area Governments.  On Shaky Ground City Maps, City of San Francisco.  October, 1995.

[78]   Liquefaction is the rapid transformation of loose, saturated sand or soil to a fluid-like state due to groundshaking during an earthquake.  The loss of pore pressure in the material causes it to lose its shear strength resulting in soil losing its bearing capacity and spreading laterally or vertically.

[79]  National Pollutant Discharge Elimination System (NPDES) General Permit for Storm Water Discharges Associated With Construction Activity (General Permit) Water Quality Order 99-08-DWQ.

[80]   Lee, T.  Section Engineer, San Francisco Department of Public Works, Bureau of Environmental Regulation and Management, personal communication with BASELINE, 25 November, 1996.

[81]   Ibid.  

[82]   California Regional Water Quality Control Board, San Francisco Bay Region.  Water Quality Control Plan, San Francisco Bay Basin (Region 2), Amended November 2005.

[83]   Ibid.

[84]   Loiacono, J.  Section Manager, Environmental Engineering, San Francisco Department of Public Works, Southeast Water Pollution Control Plant.  Personal communication with BASELINE, 20 November, 1996.

[85]   San Francisco Planning Department, San Francisco Waterfront Land Use Plan, Final Environmental Impact Report.  January 8, 1997.

[86]   California Regional Water Quality Control Board.  NPDES Permit No. CA0037664, Waste Discharge Requirements for City and County of San Francisco, Southeast Water Pollution Control Plant, North Point Wet Weather Facility and Bayside Wet Weather Facilities.  June 2002.

[87]   City and County of San Francisco, Public Utilities Commission, Bureau of Environmental Regulation and Management.  Requirements for Batch Wastewater Discharges.  11 April, 1994.

[88]   Rantz, S.E.  Mean Annual Precipitation Depth Frequency Data for the San Francisco Bay Region, California, U.S. Geological Survey, Open File Report 3019-21, 1971

[89]   Ibid.

[90]   Loiacono, J.  Section Manager, Environmental Engineering, San Francisco Department of Public Works, Southeast Water Pollution Control Plant.  Personal communication with BASELINE, 20 November, 1996.

[91]   Ibid.

[92]   California Regional Water Quality Control Board.  Order No. 95-039, NPDES Permit No. CA0038610, Waste Discharge Requirements for City and County of San Francisco, Bayside Wet Weather Facilities, 15 February, 1995.

[93]   Federal Emergency Management Agency.  National Flood Insurance Program, Community Status Book, January, 1997.

[94]   San Francisco Enterprise GIS, Elevation Contours Data Set developed from Digital Elevation Model used for 2001 orthophotography. San Francisco City Datum is equal to +8.616 feet National Geodetic Vertical Datum (NGVD).

[95]   Mission Bay Plan FEIR, Volume 2, page VI.L.9 and Volume 4, page XV.J.4

[96]   Titus, J., and V. Narayanan.  The Probability of Sea Level Rise, U.S. Environmental Protection Agency, EPA 230-R-95-008.  October, 1995.

[97]   Gornitz, V. and L. Lebedeff.  “Global Sea-Level Changes During the Past Century” published in Sea-Level Change and Coastal Evolution, SEPM Publication, No. 41, p. 3-16.  1987.

[98]   Gleick, P. and E. Maurer.  Assessing the Costs of Adapting to Sea Level Rise, A Case Study of san Francisco Bay, Pacific Institute for Studies in Development, Environemnt and Security.  February, 2004.

[99]   Ritter, J.R. and W.R. Dupre.  Map showing potential inundation by tsunami in the San Francisco Bay Region, California.  U.S. Geological Survey Miscellaneous Field Studies Map MF-480.  1972

[100] Garcia, A.W., and J.R. Houston.  Type 16 Flood Insurance Study:  Tsunami Predictions for Monterey and San Francisco Bays and Puget Sound, Final Report, prepared for the Federal Insurance Administration, Department of Housing and Urban Development, Technical Report H-75-17.  November, 1975.

[101] Phillips, S.P., S. Hamlin, and E. Yates.  Geohydrology, Water Quality, and Estimation of Groundwater Recharge in San Francisco, California, 1987-1992, U.S. Geological Survey Water Resources Investigations, Report 13-4019.  1993.

[102] Lee & Praszker.  Geotechnical Report, Idealized Subsurface Profiles, San Francisco Museum of Modern Art, San Francisco, California.  14 August, 1990.

[103] San Francisco Public Utilities Commission.  San Francisco Groundwater Master Plan.  1997

[104] San Francisco Bay Regional Water Quality Control Board. Update on the Status of the Groundwater Basin Plan Amendments (August 2004) available at: http://www.swrcb.ca.gov/rwqcb2//basin_plan_ammend.htm.

[105] The federal Endangered Species Act (FESA) of 1973 declares that all federal departments and agencies shall use their authority to conserve endangered and threatened plant and animal taxa.  The California Endangered Species Act (CESA) of 1984 parallels the policies of FESA and pertains to native California taxa.

[106] Jurisdiction of the Corps is established through the provisions of §404 of the Clean Water Act, which prohibits the discharge of dredged or fill material into "waters," including wetlands and unvegetated "other waters," of the United States without a permit.  All three of the identified technical criteria must be met for an area to be identified as a wetland under Corps jurisdiction, unless the area has been modified by human activity.

[107] Hazardous materials are defined as any material that, because of its quantity, concentration, or physical chemical characteristics, poses a significant present or potential hazard to human health and safety, or to the environment if released into the workplace.  Hazardous materials include, but are not limited to, hazardous substances, hazardous waste, radioactive materials, and any material which a handler or the administering agency has a reasonable basis for believing that it would be injurious to the health and safety of persons or harmful to the environment if released into the workplace or the environment (HSC 25501).

[108] No. 96.218E, Hazardous Materials Technical Report by Baseline Environmental Consulting, June, 1997

[109] Phase I Environmental Site Assessment and Site History Report, Central Subway Alignment, San Francisco, California, Revision 1, December 18, 2003.

[110] Addendum to Phase I Environmental Site Assessment and Site History Report, Task 1.02-03, Hazardous Material Investigations, Revision 0, April 1, 2005.

[111] Phase II Hazardous Materials Investigation Report, for the Fourth/Stockton Alignment, Task 1.02-03, Hazardous Material Investigations, Revision 0, May 18, 2006.

[112] Addendum No. 2 to Phase I Environmental Site Assessment and Site History Report, Task 1.02-03, Hazardous Material Investigations, Revision 0b, February 9, 2007.

[113] Applicability and implementation of remedial action oversight must comply with the requirements in the Health and Safety Code, Section 512.

[114] Western Regional Climate Center, Western U.S. Historical Summaries (Individual Stations), 2007; www.wrcc.dri.edu

[115] California Air Resources Board, The California Almanac of Emissions and Air Quality - 2006 Edition, April 2006 and Bay Air Quality Management District, Source of Inventory of Bay Area Greenhouse Gas Emissions, November 2006..

[116] California Air Resources Board, The California Almanac of Emissions and Air Quality - 2006 Edition, April 2006 and Bay Air Quality Management District, Source of Inventory of Bay Area Greenhouse Gas Emissions, November 2006..

[117] Bay Area Air Quality Management District, Source Inventory of Bay Area Greenhouse Gas Emissions, November 2006.

[118] Sound is caused by vibrations that generate waves of minute air pressure fluctuations in the air.  Air pressure fluctuations that occur from 20 to 20,000 times per second can be detected as audible sound.  The number of pressure fluctuations per second is normally reported as cycles per second or Hertz (Hz).  Different vibrational frequencies produce different tonal qualities for the resulting sound.