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HomeMy Public PortalAboutSan Mateo Creek Flood Control ImprovementsCity of San Mateo San Mateo Creek Flood Control Improvements Initial Study/ Environmental Assessment Final November 12, 1999 Prepared for: .. City of San Mateo Public Works Department 330 West 20t°Avenue San Mateo, California 94403 Prepared by: MI -IA Environmental Consulting, Inc. .520 South Camino Real, Suite 800 San Mateo, California 94402 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 City of San Mateo San Mateo Creek Flood. Control Improvements Final November 12, 1999 Prepared for: City of San Mateo Public Works Department 330 West 20th Avenue San Mateo, California 94403 Prepared by: MHA Environmental Consulting, Inc. 520 South Camino Real, Suite 800 San Mateo, California 94402 Initial Study/ Environmental Assessment 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Table of Contents 1.0 PROJECT DESCRIPTION 1-1 1.1 Project Overview 1-1 1.2 Design Characteristics 1-3 1.3 Project Construction 1-3 1.4 Project Maintenance 1-7 1.5 Permit Requirements 1-7 2.0 ENVIRONMENTAL SETTING 2-1 2.1 Project Environmental Setting 2-1 2.2 Related Projects 2-2 2.3 Evaluation of Environmental Impacts 2-2 3.0 CHECKLIST 3-1 3.1 Aesthetics 3-1 3.2 Agricultural Resources 3-3 3.3 Air Quality 34 3.4 Biological Resources 3-6 3.5 Cultural Resources 3-10 3.6 Geology and Soils 3-12 3.7 Hazards and Hazardous Materials 3-13 3.8 Hydrology and Water Quality 3-15 3.9 Land Use and Planning 3-18 3.10 Mineral Resources 3-19 3.11 Noise 3-20 3.12 Population and Housing 3-22 3.13 Public Services 3-23 3.14 Recreation 3-24 3.15 Transportation/Traffic 3-25 3.16 Utilities and Service Systems 3-27 3.17 Mandatory Findings of Significance 3-29 3.18 Sources 3-31 Figures Figure 1: Project Location 1-2 Figure 2: Norfolk Street Bridge Reconstruction 1-4 Figure 3: Example Cross Section of Concrete Levee Wall at FEMA Station 2415 1-5 Table Table 1: San Mateo Creek Improvements Permit Requirements 1-7 San Mateo Creek Improvements Project November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1.0 PROJECT DESCRIPTION 1.1 Project Overview PROJECT SUMMARY The City of San Mateo, Public Works Department, proposes to implement the San Mateo Creek Improvements Project to address the Federal Emergency Management Agency (FEMA) requirements of protecting low-lying areas in the vicinity of San Mateo Creek from flooding during a 100 -year tidal or storm event. The improvements will be between Highway 101 and J. Hart Clinton Drive (Figure 1). The project consists of reconstructing portions of the Norfolk Street Bridge and the construction of a concrete apron in the bridge vicinity (i.e., channel lining). In addition, cast -in -place concrete walls will be constructed along the top of the north and south levees of the San Mateo Creek between northbound Highway 101/3rd Avenue off -ramp and J. Hart Clinton Drive. PROJECT NEED The City of San Mateo is required by FEMA to address the flood threat to homes in the vicinity of San Mateo Creek from Highway 101 to the Bay. FEMA requires 3 feet of freeboard above the 100 -year storm event level and 2 feet of freeboard above the 100 -year tidal event level. Church Water Consultants, a hydrologic consulting firm, evaluated the flow rates and velocity for the creek and recommended flood improvements to the City to meet the FEMA requirements. The project implements the recommended improvements. Need for Norfolk Street Bridge Reconstruction The Norfolk Street Bridge, which crosses the San Mateo Creek, will be reconstructed to raise its elevation by approximately 1 foot. This reconstruction will provide sufficient capacity under the bridge to pass the FEMA 100 -year storm event. It may be necessary to remove mud and debris currently under the bridge; this maintenance activity may need to be repeated annually. San Mateo Creek Improvements Project 1-1 November 12, 1999 N M I E= MI M MIN =_— I_ N= M I M I m 4 0 CD n 0 t. et qg Figure 1: Project Location Project: San Mateo Creek Impro vements Project 11 .3 !OAHU ST ' 'A V/' 1 3 IUA HU AVL I L 0 ST NORTON ST IA AVE YOUNG ST NNA ST AMPHLETT D HOWE Sr RAND AVE r-• ti 4 SAYS ORE FRWY/U.S. 1 0 S BAYSHORE BLVD 3 GLORIA CT PATRICIA AVE S NORF■ ILK ST RAND ST FALLON AVE OCEANVIEW AVE BIKE PATH & WALK -I nd N AMPHLETT B S BAYSHOHL 13 S KINGSTON LINDBERGH ST o� z NTARIO Si 7WFi_(. ST m UEBEC AV CHESTER ri D ,VC AV BAYFRONT SHORELINE PARt 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1: PROJECT DESCRIPTION Need for Concrete Apron A concrete apron would be constructed under the new bridge and would extend approximately 30 feet downstream of the bridge. This concrete apron would line the creek bed and help maintain flows under the bridge by facilitating mud and debris removal during maintenance. Need for Concrete Levee Wall Construction Concrete walls, of 1 -to 3 -foot height, would need to be constructed along the levees on both sides of the creek. The walls would be constructed from the Highway 101/3rd Avenue off -ramp to J. Hart Clinton Drive to provide the necessary freeboard. The wall height will include 3 feet of freeboard above the 100 -year storm event level and 2 feet of freeboard above the 100 -year tidal event level, as required by FEMA. 1.2 Design Characteristics NEW BRIDGE DIMENSIONS AND DESIGN FEATURES The Norfolk Street Bridge over San Mateo Creek will be removed and replaced with a new bridge (Figure 2). The bottom of the new bridge deck will be raised by -approximately 1 foot to increase the hydraulic capacity under the bridge. The approaches to Norfolk Street Bridge will be reconstructed to accommodate the new bridge profile. The bridge will be widened by approximately 8 feet (4 feet on each side) to provide a bike lane. The bridge abutments will also be widened by 8 feet to conform to the new bridge deck. CONCRETE APRON DIMENSIONS AND DESIGN FEATURES A concrete apron would be constructed under the new bridge and would extend approximately 30 feet downstream of the bridge. The apron would be approximately 30 feet wide and 116 feet long and would line the creek bed. CONCRETE LEVEE WALL DIMENSIONS AND DESIGN FEATURES Cast -in -place concrete walls would be constructed along the top of levees on both sides of the San Mateo Creek from the Highway 101 /3rd Avenue off -ramp to J. Hart Clinton Drive. The existing levees are uneven and the walls will vary in height from 1 to 3 feet above the existing top of levees to obtain the necessary freeboard. The walls each will be approximately 2,000 feet long. The top of the walls will be about 1 foot wide and the spread footing will be approximately 6 feet wide (Figure 3). 1.3 Project Construction CONSTRUCTION SCHEDULE Total project construction would last approximately 6 months. The Norfolk Street Bridge reconstruction will last approximately four months. The construction period window starts around April and ends in October. Construction would be conducted Monday through Friday from approximately 8am to 5pm. Due to resource constraints, both levee walls may not be constructed at the same time. The south levee wall would be constructed first. San Mateo Creek Improvements Project 1-3 November 12, 1999 L I r^�`\ _5 ) ---� -� , -TEM A-El NE— } / --19+00- (APPROX.) LIMITS OFJ W ___ W ETLANDS _ yam twit: 'Or W ALL FOOTING COFFERDAM TEMPORARY CONSTRUCTION ZONE A' II 86' (NEW ) (^-- 78' (E%I STING) - I. LW1 LINE 220,'± TEMPORARY �. -�_ ALTERNATIVE PIPE %--: CULVERT; 'I I i 0 CC O z EXIST R/W 80' BCC --APRON - —17+ do SAN MATEO CREEK 16+ 00 10'. . - _L0+00. 7 - TEMPORARY CONST, COFFERDAM„ RUCT ION ZONE 8 SCALE: 1"=40' \A WE TCANDS• Cha in lin k railing type 7, typ Elv e 108.80 10'-6" Norfolk Street Bridge Cro ss Section (Lookin g So uth) 13'- 0" 12'-0" Lane Lane 43' -0" Lane Me dian 6'-6"± (Stage 2 constru ction ) 29'-6" travel way (Stage 1 traffic) 10.-0" 10'-6" Lan e LJ Bottom of chan ne l Lane 27. Lane Lone Lone 32'-0" travel w ay ike lane (Stage 2 traffic) 43'-0" PG 10.-0" Lane (Stage 1 co nstruction) 10'-0" 12'-0" L� • • N v Lane L ane 2% 1:1 r� El ve 108 .80 _r—Co nc barrier r type 26 I (mod), typ 1� V u ; Closure po ur n Exi st bridg e Exist grade Post tensi oned c onc slab Figure 2: Norfolk Street Bridge Reconstruction S OU RCE: Mark Thomas & Co, I nc . Mf.Q \ Enviro nmental Co nsulting, Inc. Project: San Mateo Creek Improvements Pr oject = = — — — — E N N I N N = = = M Appro ximat e Edge of Wetland 100 -year Storm Event San Mateo Creek SO UR CE: Ma rk T ho ma s & C o, Inc. Appr oximat e Limits of Construction Imp act 6' EL oint Power Pole Line vi 1 8' 7 t Fence Scal e 1 inch = 5 Feet Figure 3: Example C ro ss Section of Co ncrete Levee Wall at FEMA Statio n 2415 Project: San Mateo Creek Impr ovements Pr oject 1V1A J I. Environmental Consulting, Inc. 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1: PROJECT DESCRIPTION CONSTRUCTION METHODS Bridge Reconstruction Cofferdams will be temporarily built in the San Mateo Creek to direct water away from the bridge construction zone during bridge reconstruction (Figure 2). The cofferdams will be constructed of sandbags, which will be deposited in the creek by a crane. One dam will be approximately 50 feet upstream of the bridge and the other dam will be approximately 80 feet downstream of the bridge. A 3 -foot diameter pipe or two, 2 -foot diameter pipes will be placed between the dams to allow the creek water to flow through the construction zone. The number and size of pipe(s) will be based on calculations of the runoff in the area. The cofferdams and pipe(s) will be removed after bridge reconstruction is . completed. Norfolk Street is an arterial roadway and bridge reconstruction will be staged to minimize impacts to traffic (Figure 2). The bridge abutments would be widened to accommodate the new bridge deck, which will be 8 feet wider than the current bridge. The bridge abutments will be braced before the bridge deck is removed. During bridge reconstruction, the median island will be taken out and traffic will be shifted to one half of the bridge, with one southbound lane and two northbound lanes. The other half of the bridge will be demolished and reconstructed to include the raising and extension of the bridge and building up of the approaches to accommodate the new bridge profile. Next, the traffic will be shifted to the newly constructed side and the other side will be demolished and rebuilt. Construction is estimated to last 6 months. The new bridge will have the same number of lanes as the current bridge; three northbound lanes, two southbound lanes and will include a new bicycle lane. Concrete Apron Construction Cofferdams will be temporarily constructed in San Mateo Creek to direct water away from the bridge construction zone during the concrete apron construction. A concrete apron would line the creek bed and be constructed under the new bridge and would extend approximately 30 feet downstream of the bridge. The concrete will be poured from Norfolk Street or the fire access road on the north side of the creek. Temporary slope protection, that consists of nylon reinforced sod, will be installed adjacent to the downstream section of the apron. This measure will help prevent scour on the adjacent slopes until vegetation is naturally re-established. Concrete Levee Wall Construction Concrete levee walls will be constructed along the top of the levees, on both sides of the San Mateo Creek from the Highway 101•/3rd Avenue off -ramp to J. Hart Clinton Drive. The existing levees are uneven and the walls will vary in height from 1 to 3 feet to obtain the necessary 3 feet of freeboard above the 100 -year storm event level and 2 feet of freeboard above the 100 -year tidal event level. The walls will each be approximately 2,000 feet long. The walls will have a spread footing approximately 6 feet wide. Silt fencing will be placed between the brackish marsh along the creek and the portions of the levees to be excavated. The silt fencing will be install no more than 2 feet down from the excavated area, to prevent impacts to wetlands. The silt fencing will be maintained during construction and properly removed after construction to ensure no impacts to wetlands and the creek. A Bobcat (small front-end loader/excavator) will be used to excavate the soil on the top of the levees and the concrete walls will be cast in place. Initial Study 1-6 November 12, 1999 1: PROJECT DESCRIPTION 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Norfolk Street, a utility easement, and an access road will all be used for the equipment staging areas during construction. The south levee wall from Highway 101 to Norfolk Street will be constructed using the utility easement on the south side of the creek. The south levee wall from Norfolk Street to J. Hart Clinton Drive would be constructed using the fire access road on the north side of the creek. The concrete will be transported from the fire access road to the south side using a concrete pump. The north levee wall will also be constructed using the fire access road. 1.4 Project Maintenance Routine removal of mud and debris beneath the Norfolk Street Bridge may be necessary to provide sufficient capacity under the bridge for a 100 -year storm event. A visual inspection would be conducted annually for any build up of mud or debris under the Norfolk Street Bridge. Any significant build up of mud or debris under the bridge will be removed using a Bobcat, which would be lowered into the creek using a crane, or manually removed with shovels. 1.5 Permit Requirements Table 1 lists permits that may be required for the project. The City of San Mateo will obtain construction permits from the appropriate government agencies. Table 1: San Mateo Creek Improvements Permit Requirements Regulatory Authority Section 404 of the Clean Water Act Section 10 Permit of the Rivers and Harbors Act Section 1603 of the State Fish and Game Code - Streambed Alteration Agreement Section 401 Water Quality Certification or Waiver of Waste Discharge Requirements Consultation (through CEQA review process) Agency Army Corps of Engineers Army Corps of Engineers California Department of Fish and Game California Regional Water Quality Control Board State Historic Preservation Office Jurisdiction/Purpose Waters of the United States (includes wetlands) Structures in navigable waters Streambed alteration Requests the Board's certification that the project is consistent with state water quality standards and/or that the issuance of waste discharge requirements is waived. Cultural resources management San Mateo Creek Improvements Project November 12, 1999 1-7 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2.0 ENVIRONMENTAL SETTING 2.1 Project Environmental Setting The project site is located along San Mateo Creek, from Highway 101 to J. Hart Clinton Drive, in the City of San Mateo, California. San Mateo Creek originates at the Crystal Springs Reservoir Dam and drains into the San Francisco Bay. Its watershed encompasses a total area of 33.3 square miles. The presence of large reservoirs in the upper watershed and growth in San Mateo and Hillsborough have both greatly altered the creek. Localized flooding occurs along the urbanized portions of the creek. This flooding primarily occurs because of the reduction in channel capacity by bridges along the creek and tidal effects. The project will be implemented on a section of the creek that has been previously channeled. Man-made levees were constructed on both sides of this section of the creek to provide flood protection. The project area is at the edge of the historic salt -water marsh that was filled artificially for development. The project site consists of generally flat terrain and gentle slopes. The site is generally underlain by fill (including the levees), soft Bay mud, stiff clay, and medium dense to dense sand/grabel at depths. San Mateo is located in a seismically active part of northern California. Several faults exist in the area (e.g., San Andreas Fault, Hayward Fault). These faults are capable of producing earthquakes that may result in strong ground shaking, liquefaction, and subsidence in the project area. Open water (San Mateo Creek), brackish marsh, and disturbed landscape are the main habitats in the project area. The brackish marsh is a sensitive habitat that occurs along the margin of the creek and is relatively narrow (5-15 feet wide) due to the steep banks of the creek. The marsh is dominated by cordgrass, pickleweed, and saltgrass. The cordgrass is a hybrid between a native (Spartina foliosa) and an exotic species (Spartina alterniflora). The exotic species is native to the eastern United States and can quickly outcompete the native cordgrass. The creek is limited in value as wildlife habitat by the narrowness of the habitat corridor, its urbanized setting, and the presence of residential and commercial buildings within 50 feet of the channel limits. San Mateo Creek Improvements Project 2-1 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2: ENVIRONMENTAL SETTING The project area includes residential (single- and multi -family) and commercial (neighborhood and service) zoning. San Mateo Creek is designated as open space in the City of San Mateo General Plan. Norfolk Street is an arterial roadway. The traffic condition at the intersection of Norfolk Street and Third Avenue.(near the project site) has a Level of Service C designation, which is defined as: • Stable flow • Acceptable delay, with an occasional wait beyond one signal cycle • Back-ups possible behind turning vehicles 2.2 Related Projects The City of San Mateo, Parks and Recreation Department has been working on the Shoreline Parks Master Plan. The Master Plan includes improvements of existing parks, additional parking, enhancing trails, and active and passive recreational facilities. The project also provides for the enhancement of the wetlands and wildlife habitat. San Mateo Creek, from Highway 101 to the San Francisco Bay, is included in the Shoreline Parks Master Plan. 2.3 Evaluation of Environmental Impacts The California Environmental Quality Act (CEQA) Guidelines, Environmental Checklist Form (Appendix G) was used for this IS/EA to determine the environmental impacts of the project. The checklist includes a discussion section for each parameter with mitigation measures (labeled MM) added when necessary to reduce impacts. The analysis of environmental impacts related to the project is based on data gathered for this project and other related documents. A geotechnical study was conducted for the project and used in the analysis. The Research and Analysis Report for Shoreline Parks Master Plan (1999) contains studies of the land use, recreational use, hydrologic and biological resources for San Mateo Creek, from Highway 101 to the Bay, that were used to determine impacts of the project. Additional data was obtained from the sources listed at the end of the checklist (see section 3.18). The sources of information used in the analysis of each section are reference by number in the discussion. Initial Study 2-2 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3.0 CHECKLIST 3.1 Aesthetics Would the project: a) Have a substantial adverse effect on a scenic vista? b) Substantially damage scenic resources, including, but not limited to, trees, rock outcroppings, and historic buildings within a state scenic highway? c) Substantially degrade the existing visual character or quality of the site and its surroundings? d) Create a new source of substantial light or glare which would adversely affect day or nighttime views in the area? z E ❑ 0 0 ❑ 0 0 O 0 p 0 O 0 0 p Discussion: • a) San Mateo Creek is considered an open space linkage and has scenic value as a natural resource. Cast -in -place concrete walls will be constructed on both sides of San Mateo Creek from the Highway 101 /3rd Avenue off -ramp to J. Hart Clinton Drive and will extend approximately 1-3 feet above the top of the existing levees. The existing levees are uneven in height and the walls will vary in size from 1 to 3 feet above the existing levee to obtain the necessary freeboard. The walls will have a less than significant impact on the view of San Mateo Creek due to the limited size of the walls. In addition, the project is located on a section of the San Mateo Creek where the scenic value has been reduced because the creek was channeled and surrounding development. Reconstruction of the Norfolk Street Bridge will not have a significant impact on scenic views because it involves the removal and replacement of the existing bridge deck to San Mateo Creek Improvements Project 3-1 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3: CHECKLIST raise the bottom of it approximately 1 foot and to widen the deck approximately 8 feet. These improvements will not substantially change area views. [1,3,4] b) The City of San Mateo General Plan designates J. Hart Clinton Drive as a Scenic Roadway. The bicycle/pedestrian path on the north side of San Mateo Creek from Norfolk Street to J. Hart Clinton Drive is designated as a Scenic Trail. The path is also used for a fire access road. During construction, the path will be used as a staging area and will temporarily impact trail use. The concrete levee walls will not cause the permanent removal of the path or prevent use of the path after construction. The project will not substantially impact views from J. Hart Clinton Drive and will have a less than significant impact on views from the bicycle/pedestrian path. A few trees may be removed during construction but will be replaced or replanted, if possible. Rock outcroppings and historic buildings do not exist in the project area. [1,3,4,9]. c) The project will not substantially degrade the existing visual character or quality of the site and its surroundings. The project is located on a section of the San Mateo Creek where the scenic value has been reduced due to the creek being channeled and surrounding development. The concrete levee walls will have a less than significant impact on the view of San Mateo Creek due to the size of the walls. Reconstruction of the Norfolk Street Bridge will not have a significant impact on scenic views because it involves the removal and replacement of the existing bridge deck lo raise the bottom of it approximately 1 foot and to widen the deck approximately 8 feet. [1,3,4] d) No new lighting is proposed for the project; therefore, the proposed project will not increase light. The project includes a concrete wall from 1 to 3 feet in height and bridge improvements that are unlikely to increase glare.[3] Initial Study 3-2. November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3: CHECKLIST 3.2 Agriculture Resources In determining whether impacts to agricultural resources are significant environmental effects, lead agencies may refer to the California Agricultural Land Evaluation and Site Assessment Model (1997) prepared by the California Dept. of Conservation as an optional model to use in assessing impacts on agriculture and farmland. Would the project: a) Convert Prime Farmland, Unique Farmland, or Farmland of Statewide Importance (Farmland), as shown on the maps prepared pursuant to the Farmland Mapping and Monitoring Program of the California Resources Agency, to non-agricultural use? b) Conflict with existing zoning for agricultural use, or a Williamson Act contract? c) Involve other changes in the existing environment which, due to their location or nature, could result in conversion of Farmland, to non-agricultural use? V C CY o E ❑ 0 p 0 0 0 p 0 0 0 p Discussion: a) The project site is not considered Prime Farmland, Unique Farmland, or Farmland of Statewide Importance. [1,2] b) The project site is not zoned for agricultural use and a Williamson Act contract is not in place for the project area. [1,2] c) The proposed project is not located near land that is considered Farmland. The project would not result in the conversion of Farmland to non-agricultural uses. [1,2] San Mateo Creek Improvements Project 3-3 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3: CHECKLIST 3.3 Air Quality Where available, the significance criteria established by the applicable air quality management or air pollution control district may be relied upon to make the following determinations. Would the project: a) Conflict with or obstruct implementation of the applicable air quality plan? b) Violate any air quality standard or contribute substantially to an existing or projected air quality violation? c) Result in a cumulatively considerable net increase of any criteria pollutant for which the project region is non -attainment under an applicable federal or state ambient air quality standard (including releasing emissions which exceed quantitative thresholds for ozone precursors)? d) Expose sensitive receptors to substantial pollutant concentrations? e) Create objectionable odors affecting a substantial number of people? ❑ ❑ ❑ p ❑ 0 0 0 ❑ 0 p ❑ ❑ 0 0 0 ❑ 0 ❑ 121 Discussion: • a) The Bay Area Air Quality Management District developed the Bay Area '94 Clean Air Plan, which was revised in 1997. The goal of the CAP is to improve air quality in the region, especially for ozone, through the year 2000 and beyond. The goal will be achieved through tighter industry controls, cleaner cars and trucks, cleaner fuels, and increased commute alternatives. The project will not conflict with or obstruct implementation of the CAP. [3,4,10] b) The project would not violate any air quality standard or contribute substantially to an existing or projected air quality violation. During the construction phase of the project, relatively small amounts of air emissions would be produced. Emissions during the construction phase would be short-term. The emissions produced during construction can be reduced using standard construction dust and exhaust emission control practices. The following mitigation measure will reduce impacts to a less than significant level. MM -1 Prior to site grading, a grading plan shall be submitted to the city for review. The grading plan shall include measures to reduce emissions from construction Initial Study 3-4 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3: CHECKLIST equipment and wind blown soils. Measures shall include daily watering of disturbed soils until adequate cover has been established, proper maintenance of construction equipment, and standard conditions of approval in the City. [3,4,11] c) The San Francisco Bay Area Air Basin is non -attainment for 03 (ozone) at the federal and state level and non -attainment for PM10 (particulate matter less than 10 microns) at the state level. The project will not result in a cumulatively considerable net increase of 03 or PM10. During the construction phase of the project, relatively small amounts of air emissions would be produced. Emissions during the construction phase would be short-term. The emissions produced during construction can be reduced using standard construction dust and exhaust emission control practices. Emissions produced during construction would not be considered substantial and would be mitigated to less -than -significant levels (See MM -1 above). [3,4,11] d) The project would not expose sensitive receptors to substantial pollutant concentrations. The project area is surrounded by residential and commercial development. The proposed project would result in temporary and relatively small amounts of air emissions during the construction phase of the project. Emissions produced during construction would not be considered substantial and would be mitigated to less -than -significant levels (See MM -1 above). [1,3,4] e) The proposed project would not create substantial objectionable odors. [3,4] San Mateo Creek Improvements Project 3-5 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3: CHECKLIST 3.4 Biological Resources Would the project: a) Have a substantial adverse effect, either directly or through habitat modifications, on any species identified as a candidate, sensitive, or special status species in local or regional plans, policies, or regulations, or by the California Department of Fish and Game or U.S. Fish and Wildlife Service? b) Have a substantial adverse effect on any riparian habitat or other sensitive natural community identified in local or regional plans, policies, regulations or by the California Department of Fish and Game or US Fish and Wildlife Service? c) Have a substantial adverse effect on federally protected wetlands as defined by Section 404 of the Clean Water Act (including, but not limited to, marsh, vernal pool, coastal, etc.) through direct removal, filling, hydrological interruption, or other means? d) Interfere substantially with the movement of any native resident or migratory fish or wildlife species or with established native resident or migratory wildlife corridors, or impede the use of native wildlife nursery sites? e) Conflict with any local policies or ordinances protecting biological resources, such as a tree preservation policy or ordinance? f) Conflict with the provisions of an adopted Habitat Conservation Plan, Natural Community Conservation Plan, or other approved local, regional, or state habitat conservation plan? Discussion: ra :-• e ▪ O '� v A ,tom 00 L cV+ n •O .� 9. F- W o k u^. o. lej G y y G' E. E G �' OOAA L o L OA i-- a.co ca .5. p - iii '" ❑ 0 0 0 ❑ 0 E ❑ ❑ 0 0 0 ❑ D 0 0 ❑ 0 0 ❑ a ❑ ❑ 0 a) Two special -status species occur or may occur in San Mateo Creek, steelhead trout and marsh gumplant. The federally threatened California red -legged frog (Rana aurora draytonii) is not expected to occur in the project site because the creek and marsh are too saline. Steelhead trout (Central Coastal Evolutionarily Significant Unit) (Oncorhynchus mykiss), a federally threatened species, was reported to occurred in San Mateo Creek in 1989 Initial Study 3-6 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3: CHECKLIST and still has the potential to occur in the creek. Steelhead trout is an anadromous form of the rainbow trout (i.e., it returns to the ocean for part of its life cycle). Steelhead trout live the first part of their life in freshwater habitat and mature in the ocean. The steelhead trout generally return to their parent stream to spawn. In central California, the trout swim upstream when the fall rains begin and spawn in the spring. Most spawning migration normally occurs from December through March. A Streambed Alteration Agreement will be obtained from the California Department of Fish and Game before any in -stream work will begin. Water will temporarily be diverted from a portion of the creek near the Norfolk Street Bridge during bridge reconstruction. Cofferdams will be used for the water diversion. Either a 3 -foot diameter pipe or two, 2 -foot diameter pipes will be placed between the cofferdams to allow water to flow through the construction zone. The pipe(s) will allow fish to swim through the construction zone. Siltation in the creek from construction could reduce oxygen levels in the water and, in turn, discourage migrating adult steelhead. Erosion control practices will be used during construction, such as silt fencing, to minimize the siltation of soils into the creek (see MM -9 in Section 3.6 Geology and Soils). Bridge reconstruction will occur between April and October, for approximately four months, when steelhead trout spawning migration is not likely to occur. After construction, the cofferdams will be removed and the creek will return to its previous course. As a result, the project will have a temporary and less -than -significant impact to steelhead trout. Marsh gumplant (Grindelia stricta var.augustifolia) occurs on the upper margins of the brackish marsh along San Mateo Creek. Marsh gumplant is listed as a special -status species in the San Mateo County General Plan, but it is not state or federally listed. Approximately five marsh gumplants may be removed during reconstruction of the Norfolk Street Bridge. This removal will not have a substantial adverse effect because the species is common in the project area and readily recolonizes disturbed areas adjacent to tidal brackish marsh. Construction of the levee walls will not impact the marsh gumplant because the wall construction will not impact the brackish marsh. [3,4,6,9,13] b) The only sensitive habitats in the project area are the open water and brackish marsh in and along the edges of San Mateo Creek. The project area includes San Mateo Creek and the habitat adjacent to the creek, which includes brackish marsh. Waters of the United States, which includes the creek and the adjacent brackish marsh, will be temporarily and permanently impacted during reconstruction of the Norfolk Street Bridge. These waters will be permanently impacted by construction of the concrete apron beneath the bridge and 30 feet downstream of the bridge. Construction of the levee walls will not impact the sensitive habitats in the project area. Maintenance to remove debris from under the bridge will not impact wetlands due to the methods used (see Project Description). Approximately 3,765 square feet (0.09 acres) of Waters of the United States will be permanently impacted by the project, about 310 square feet (0.01 acres) of which is brackish marsh. Approximately 3,225 square feet (0.07 acres) of Waters of the United States will be temporarily impacted by construction, about 1,605 square feet (0.04 acres) of which is brackish marsh. The project will have a less than significant impact on this sensitive natural community due to the minimal loss of wetlands. San Mateo Creek Improvements Project 3-7 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3: CHECKLIST Erosion control practices will be used during construction, such as silt fencing, to minimize the siltation of soils into the wetlands and the creek (see Section 3.8 Hydrology and Water Quality). [3,4,9] c) The project will result in the permanent loss of approximately 0.01 acres of wetland and a temporary impact to 0.04 acres of wetland during construction. Erosion control practices will be used during construction, such as silt fencing, to minimize the siltation of soils into the wetlands. The project will have a less than significant impact to wetlands because project plans for the bridge reconstruction and the levee walls were designed to minimize impacts to the brackish marsh adjacent to San Mateo Creek. [3,4,9] d) The creek has limited value as wildlife habitat because of the narrowness of the riparian habitat corridor (20 to 30 feet on either side of the creek), its urbanized setting, and the presence of houses and commercial development within 50 feet of the channel limits. Wildlife use is mostly restricted to San Mateo Creek, where permanent open water in the channel provides habitat for invertebrates and small fish. Fish eating birds and possibly nocturnal predators of small mammals, such as raccoons, may forage in and along the creek. The project would have a less than significant impact to migratory fish because construction would not occur during the typical spawning migration period. In addition, a pipe or pipes will be placed between the cofferdams during construction to allow movement through the construction zone. The concrete wall construction would have a less than significant impact to the • movement of wildlife species because they will be built on top of levees in an area of concentrated residential and commercial development. In addition, the walls will be constructed on artificial levees and adjacent to a portion of the San Mateo Creek that was previously disturbed when it was channeled. Birds such as barn swallows (Hirundo rustica), cliff swallows (Petrochelidon pyrrhonota), or rough -winged swallows (Stelgidopteryx serripennis) may use the underside of the Norfolk Street Bridge for nesting. It is illegal to harm migratory birds, migratory bird eggs, or their nests under the federal Migratory Bird Treaty Act (MBTA). The barn, cliff, and rough -winged swallows are migratory birds that occur in San Mateo County and are protected by the MBTA. To reduce potential impacts to nesting birds the following mitigation measure shall be performed. MM -2 Prior to bridge reconstruction, the underside of the bridge shall be surveyed by a qualified biologist for active bird nests. If active nests are found they shall be removed before egg -laying begins by a qualified biologist, in coordination with the California Department of Fish and Game. Temporary barriers shall be erected on the side of the bridge prior to construction to discourage birds from nesting. [3,4,9,16] e) The City of San Mateo has a Heritage Tree Ordinance which regulates the removal and pruning of trees with the intent of preserving as many significant trees as possible. A Heritage Tree is defined, in part, as a tree which is of historical significance. It is also defined as an indigenous tree that has a trunk with a diameter of 10 inches or more, or a non-native tree with a diameter of 16 inches or more, as measured at 48 inches above the natural grade. Two palm trees on the median of Norfolk Street, just south of the bridge, meet the Heritage tree. definition. These trees may need to be removed during bridge reconstruction. To mitigate potential impacts to a less than significant level, the following measure shall be performed. Initial Study 3-8 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1. 1 1 1 3: CHECKLIST MM -3 If any Heritage Trees must be removed during project construction, the tree shall be saved and replanted after construction. If the trees do not survive, then they will be replaced with similar trees or indigenous trees. The project would not conflict with any other local policies. The proposed project is consistent with the goals and policies of the City of San Mateo. [1,3,4] f) There are no adopted Habitat Conservation Plans or Natural Community Conservation Plans in the project area. [1,3,4,6] San Mateo Creek Improvements Project 3.9 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3: CHECKLIST 3.5 Cultural Resources o • � s ,FLq g q V m y .qj V C d 75' itz P W r O F W y o • �E v m� o u m. 3•• Would the project: a) Cause a substantial adverse change in the significance of a historical resource as defined in §15064.5? b) Cause a substantial adverse change in the significance of an archaeological resource pursuant to §15064.5? c) Directly or indirectly destroy a unique paleontological resource or site or unique geologic feature? d) Disturb any human remains, including those interred outside of formal cemeteries? o Z Discussion: a) According to state and federal inventories, no historical resources exist on the project site. However, the Norfolk Street Bridge is going to be 50 years old in the year 2000, when bridge reconstruction is expected to occur. The Office of Historic Preservation has determined that buildings, structures, and objects 50 years or older may be of historic value. Given that the bridge will qualify as a historic resource, its significance must be evaluated. The following mitigation measure will be implemented to ensure that impacts to historic resources are less than significant. MM -4 Prior to project construction, the Office of Historic Preservation will be consulted by a qualified archaeologist about potential project impacts to historic resources and section 106 compliance. b) The project site exists on fill and bay mud. The portion of San Mateo Creek where the project is located has been previously disturbed because it was channeled and levees were constructed adjacent to the creek. There is a moderate possibility of identifying Native American sites. Native American archaeological sites in this section of San Mateo County tend to be situated along the edge of the historic bay and marsh margins. The Ohlone Indians inhabited the San Francisco Bay Area prior to the settlement of the area by Europeans. The Ohlone were composed of several sub -tribes called triblets. The triblet that occupied the City of San Mateo was called the Salson or Shalshon. The Salson greatest habitations were situated near San Mateo Creek and the Bay Marshes. The project site is located along a portion of San Mateo Creek. A shellmound site is located within a 1/2 mile of the project area and is in a similar environment. To mitigate potential impacts to archaeological resources to a less than significant level, the following measure shall be performed. MM -5 A qualified archaeologist will be on -site during excavation for the Norfolk Street Bfidge reconstruction and the levee wall construction. During construction Initial Study 3-10 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3: CHECKLIST excavation the archaeologist and construction personnel shall look out for buried archaeological resources and human remains. If these resources are discovered, construction in the immediate area of the find shall cease until the archaeologist has studied the resources. All identified archaeological sites shall be evaluated using the California Register of Historical Resources criteria. The archaeologist shall identify the proper course of action to reduce project impacts on cultural resources. This shall include studying and reporting on the site to ensure that data is available to future researchers. Material recovered shall be donated to an appropriate repository for future study. [3,4,5,15] c) Unique paleontological resources or geologic feature are not known to exist in the project area because the site is recent fill or bay mud. Therefore, the project will not impact these resources. [4,5] d) The project site exists on fill and bay mud. The site has been previously disturbed when this portion of San Mateo Creek was channeled and during construction of the levees adjacent to the creek. There is a moderate possibility of identifying Native American sites at the project site. Native American archaeological sites in this section of San Mateo County tend to be situated along the edge of the historic bay and marsh margins. The project area is at the edge of the historic salt -water marsh and adjacent to a creek where Ohlone Indians congregated. A shellmound site is located within a 1/2 mile of the project area and is in a similar environment. To mitigate potential impacts to a less than significant level, the following measure shall be performed. MM -6 If prehistoric archaeological deposits that include human remains or objects considered "cultural items" according to the Native American Graves Protection and Repatriation Act (NAGPRA) are discovered during construction, the County Coroner shall be notified immediately and NAGPRA regulations shall be followed. If the remains are identified as American Indian, the tribe(s) shall be notified within one (1) working day and consultation will be initiated. Project activities may resume 30 days after notifying the tribe(s). Repatriation of the other categories of items (funerary objects, sacred objects, and cultural patrimony) shall be based on evidence that indicates whether or not the original acquisition of the object was from an individual that had the authority to separate the item from the tribal group. [3,4,5,15] San Mateo Creek Improvements Project 3-11 November 12, 1999 1 1 1 1 .1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3: CHECKLIST 3.6 Geology and Soils Would the project: a) Expose people or structures to potential substantial adverse effects, including the risk of loss, injury, or death involving: i) Rupture of a known earthquake fault, as delineated on the most recent Alquist-Priolo Earthquake Fault Zoning Map issued by the State Geologist for the area or based on other substantial evidence of a known fault? Refer to Division of Mines and Geology Special Publication 42. ii) Strong seismic ground shaking? iii) Seismic -related ground failure, including liquefaction? iv) Landslides? b) Result in substantial soil erosion or the loss of topsoil? c) Be located on a geologic unit or soil that is unstable, or that would become unstable as a result of the project, and potentially result in on- or off -site landslide, lateral spreading, subsidence, liquefaction or collapse? d) Be located on expansive soil, as defined in Table 18-1-B of the Uniform Building Code (1994), creating substantial risks to life or property? e) Have soils incapable of adequately supporting the use of septic tanks or alternative waste water disposal systems where sewers are not available for the disposal of waste water? Discussion: _ _oG C c C A° t g8 T V q F V F y 2 V t 6 F " o r" d c E y c .a y E `o 1^ den o u 0o.. iq .s. C Q) 3— , o Z E E O ❑ ❑ El ❑ 0 0 0 ❑ Q 0 0 ❑ 0 ❑ El ❑ 0 0 0 ❑ 0 0 0 o p 0 0 ❑ 0 0 El a) i) No known active or potentially active faults cross the project site; therefore, the potential for ground surface rupture due to faulting at the site is considered low. [1,5,14] ii) The project site is located in a seismically active part of northern California. Several faults (e.g., San Andreas Fault, Hayward Fault) exist in the area which are capable of producing earthquakes which may cause strong ground shaking at the site. The project area consists of fill and bay mud. Initial Study 3-12 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3: CHECKLIST MM -7 To mitigate effects to a less than significant level, ground shaking will be taken into account during the engineering design and construction of project structures. [1,3,5,14] iii) Parikh Consultants (1999) analyzed the liquefaction potential of isolated sand deposits underlying the project site for a magnitude 8 earthquake on the San Andreas Fault. According to their analyses, cohesionless soils below a depth of 50 feet and cohesionless soils above the groundwater level were considered to have low liquefaction potential. Based on soil borings, the majority of the subsoils consist of cohesive material which may be subject to liquefaction during strong earthquake shaking. MM -8 To mitigate effects to a less than significant level, engineering and construction measures will be implemented to minimize potential impacts or damage to structures resulting from liquefaction. [1,3,14] iv) The project area consists of flat terrain and gentle slopes and is not prone to landslides. Erosion control measures would be implemented during construction. [1,3,6] b) Potential exists for the erosion of fill and excavated materials during construction. Mitigation measures would be required to address wind and water erosion. Wind erosion is addressed under 3.3 Air Quality. Water erosion will be mitigated as follows: MM -9 Prior to site disturbance, a grading plan shall be prepared which includes a construction erosion control plan with Best Management Practices (BMP's) designed to minimize sediment in site runoff during construction (e.g., silt fencing between construction area and the San Mateo Creek). The project will result in a positive effect after construction because the concrete walls will prevent soils from running off the top of the levee and entering the San Mateo Creek. [3,4] c) The project site is generally underlain by fill (including the levees), soft Bay Mud, stiff clay, and medium dense to dense sand/gravel at depths. The levee material ranges from firm sandy loam clay to loose clayey sand and silty sand mixed with clay. The levee material typically extends to a depth of about 5 to 6 feet (east of Norfolk Street) and 8 to 10 feet (between Norfolk Street and Highway 101) below the top of the levee. The project is unlikely to cause or be subject to landslides due to the moderate slope of the terrain. Site soils could be subject to lateral spreading, subsidence, liquefaction, or collapse. Engineering and construction design will minimize potential impacts or damage to project structures, which could be cause by an unstable substrate. MM -10 A qualified engineer shall provide recommendations for the design of the levee walls and bridge improvements that address lateral spreading, subsidence, liquefaction, and collapsible soils. [1,3,5,14] d) Soil surveys have been conducted at the project site in areas where structures would be erected. Expansive soils are present in the project area. Expansive soils around the levee walls will provide a beneficial impact because they will swell during flooding and help prevent water from seeping below the levee wall and undermining the protection that the wall will provide. To mitigate potential impacts to project structures to a less than significant level the following measure will be implemented. MM -11 Expansive soils will be considered in the engineering design of the project structures to minimize effects of shrinking and swelling. [3,4,14] e) The project will not require wastewater disposal systems. [3] San Mateo Creek Improvements Project 3-13 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3: CHECKLIST 3.7 Hazards and Hazardous Materials Would the project: a) Create a significant hazard to the public or the environment through the routine transport, use, or . disposal of hazardous materials? b) Create a significant hazard to the public or the environment through reasonably foreseeable upset and accident conditions involving the release of hazardous materials into the environment? c) Emit hazardous emissions or handle hazardous or acutely hazardous materials, substances, or waste within one -quarter mile of an existing or proposed school? d) Be located on a site which is included on a list of hazardous materials sites compiled pursuant to Government Code Section 65962.5 and, as a result, would it create a significant hazard to the public or the environment? e) For a project located within an airport land use plan or, where such a plan has not been adopted, within two miles of a public airport or public use airport, would the project result in a safety hazard for people residing or working in the project area? f) For a project within the vicinity of a private airstrip, would the project result in a safety hazard for people. residing or working in the project area? Impair implementation of or physically interfere with an adopted emergency response plan or emergency evacuation plan? h) Expose people or structures to a significant risk of loss, injury or death involving wildland fires, including where wildlands are adjacent to urbanized areas or where residences are intermixed with wildlands? g) Discussion: 74 t o �E ❑ 0 Q 0 ❑ 0 ❑ 9 ❑ _. 0 0 9 ❑ 0 ❑ ❑ 0 0 p 0 0 ❑ 9 ❑ Q 0 ❑ ❑❑ ❑ 9 a) Hazardous materials associated with construction (e.g., diesel fuel, oil, gasoline) would be used in small amounts during project construction. These materials would not create a significant hazard. [3,4] San Mateo Creek Improvements Project November 12, 1999 343 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3: CHECKLIST b) The project would not cause a release of significant amounts of hazardous materials into the environment. Small amounts of hazardous materials associated with construction (e.g., diesel fuel, oil, gasoline) would be used. Any foreseeable upset or accident condition would not result in the release of significant amounts of hazardous material's. [3,4] c) Implementation of the project would not result in emissions of acutely hazardous substances. Hazardous materials or acutely hazardous materials would not be handled or emitted within 0.25 mile of an existing or proposed school. [3,6] d) The project site is not a hazardous materials site. [1,6] e) The project is not located within an airport land use plan area. f) g) The project site is not located in the vicinity of a private airstrip. [1,4,6] During the Norfolk Street Bridge reconstruction, the median island will be taken out and traffic will be shifted to one half of the bridge, with one southbound lane and two northbound lanes. The other half of the bridge will be demolished and reconstructed to include the raising and extension of the bridge and the approaches will be built up. Next, the traffic will be shifted to the newly constructed side and the other side will be demolished and rebuilt. Construction is estimated to last 6 months: Traffic will be able to get across the bridge during construction if an emergency situation were to occur. In addition, alternate routes in the project area may also be used in an emergency situation. The project would not interfere with an adopted emergency response plan or emergency evacuation plan. During construction, the fire access road on the north side of the creek would be used as a staging area. The following mitigation measure will be implemented to ensure that impacts to fire access are less than significant. • MM -12 Prior to construction, the local fire department will be contacted to coordinate fire access. The fire department will be given the schedule of when the fire access road on the north side of the creek will be used for staging and where staging will occur on the road. [3,4] h) Wildlands do not exist in the project vicinity. Fire risk in the project area is low and will remain low after project construction. [1,3] Initial Study 3-14 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 j) 3: CHECKLIST 3.8 Hydrology and Water Quality Would the project: a) Violate any water quality standards or waste discharge requirements? b) Substantially deplete groundwater supplies or interfere substantially with groundwater recharge such that there would be a net deficit in aquifer volume or a lowering of the local groundwater table level (e.g., the production rate of pre-existing nearby wells would drop to a level which would not support existing land uses or planned uses for which permits have been granted)? c) Substantially alter the existing drainage pattern of the site or area, including through the alteration of the course of a stream or river, in a manner which would result in substantial erosion or siltation on- or off -site? d) Substantially alter the existing drainage pattern of the site or area, including through the alteration of the course of a stream or river, or substantially increase the rate or amount of surface runoff in a manner which • would result in flooding on- or off -site? e) Create or contribute runoff water which would exceed the capacity of existing or planned stormwater drainage systems or provide substantial additional sources of polluted runoff? f) Otherwise substantially degrade water quality? g) Place housing within a 100 -year flood hazard area as mapped on a federal Flood Hazard Boundary or Flood Insurance Rate Map or other flood hazard delineation map? h) Place within a 100 -year flood hazard area_structures which would impede or redirect flood flows? i) Expose people or structures to a significant risk of loss, injury or death involving flooding, including flooding as a result of the failure of a levee or dam? Inundation by seiche, tsunami, or mudflow? A3 ga 0 G V A u:tsJ y,:...a `^K c .0-- d. - �E in 0 0 p 0 0 0 0 O ❑ E 0 O 0 p 0 O 0 0 p ❑ 0 p ❑ ❑ . ❑ 0 0 ❑ 0 I ❑ 0 0 0 0 0 0 p 0 San Mateo Creek Improvements Project 3-15 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3: CHECKLIST Discussion: a) The project does not require a waste discharge permit. Project construction could create conditions leading to soil erosion and, in turn, may result in siltation of the San Mateo Creek. The project would not violate water quality standards with implementation of MM -9 in section 3.6 Soils and Geology. [3,4] b) The project would not affect groundwater resources in the project area because the project does not use groundwater. The project will not substantially increase impervious surfaces and will not change groundwater recharge in the area. [3,4] c) The project will involve the construction of concrete walls along the levees of San Mateo Creek from the northbound Highway 101/3rd Avenue off -ramp to J. Hart Clinton Drive. The concrete walls will not affect drainage in the area; existing drainage patterns will be maintained. The concrete walls will not result in substantial erosion or siltation on- or off -site. The walls will be beneficial by reducing erosion. Cofferdams will be constructed and be placed in the San Mateo Creek during bridge reconstruction and concrete apron construction. One dam will be placed approximately 50 feet upstream of the bridge and the other dam will be placed approximately 80 feet downstream of the bridge. A pipe (or two) will be placed between the dams to allow the creek water to flow through the construction zone. The size of the pipe(s) will be calculated and based on runoff in the area. The cofferdams will be in place during project construction, approximately 6 months. This alteration of a portion of the San Mateo Creek course will be temporary and will not result in substantial erosion or siltation on- or off -site. [3,4] d) The project will involve the construction of concrete walls along the top of levees of San Mateo Creek. The concrete walls will not affect drainage in the area; existing drainage patterns will be maintained. The concrete walls will not result in flooding on - or off -site because they will not increase the rate or amount of surface runoff or reduce its flows. The walls are proposed to meet Federal Emergency Management Agency (FEMA) freeboard requirements for a 100 -year tidal or storm event. Cofferdams will be constructed and be placed in the San Mateo Creek during bridge reconstruction and concrete apron construction. One dam will be placed approximately 50 feet upstream of the bridge and the other dam will be placed approximately 80 feet downstream of the bridge. A pipe will be placed between the dams to allow the creek water to flow through the construction zone. The size of the pipe will be calculated and based on runoff in the area. The cofferdams will be in place during project construction, 6 months. This alteration of a portion of the San Mateo Creek course will be temporary and will not result in flooding_on- or off -site because construction will occur in the summer, which is the dry season when flows are low. [3,4] e) The project will not substantially increase impervious surfaces and, therefore, will not create or contribute runoff water which would exceed the capacity of existing or planned stormwater drainage systems. Project construction could create conditions leading to soil erosion and, in turn, may result in siltation of the San Mateo Creek. The project would not provide additional sources of polluted runoff with implementation of the following mitigation measure. [3,4] 0 Project construction will not substantially degrade the water quality of the San Mateo Creek with the implementation of erosion and siltation control mitigation measures. Initial Study 3-16 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 j) 3: CHECKLIST Project implementation will not degrade water quality because of its nature as FEMA improvements designed to allow increased flows, additional freeboard, and lower maintenance. [3,4] g) The project does not include the construction of housing. [3,4] h) The project involves the construction of concrete levee walls on both sides of San Mateo Creek in order to provide the required freeboard for flood control. The Norfolk Street Bridge, which crosses San Mateo Creek, will be reconstructed to raise its bottom elevation by approximately 1 foot to increase flows under the bridge. These structures are proposed to protect low-lying areas in the project vicinity from flooding during a 100 -year tidal or storm event by providing additional freeboard required by FEMA. Cofferdams will be temporarily placed in the San Mateo Creek during project construction. Construction will occur in the summer, which is typically the dry season and flooding will not be expected to occur during this time. Therefore, the coffer dams would not impede or redirect flood flows.[3,4] i) The Norfolk Street Bridge, which crosses San Mateo Creek, will be reconstructed to raise its bottom elevation by approximately 1 foot to increase flows under the bridge. These improvements are proposed to meet FEMA freeboard requirements for a 100 - year tidal or storm event. The project will provide a benefit by protecting low-lying areas of the City of San Mateo south of San Mateo Creek between Highway 101 and San Francisco Bay from flooding during a 100 -year tidal or storm event. [3,4] Portions of the concrete levee wall close to the bay could potentially be exposed to inundation by a tsunami. Due to the nature of the project structures, inundation by a tsunami would not pose a significant threat to human safety or property. [3,4,6] San Mateo Creek Improvements Project 3-17 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 .1 1 1 1 3: CHECKLIST 3.9 Land Use and Planning Would the project: a) Physically divide an established community? b) Conflict with any applicable land use plan, policy, or regulation of an agency with jurisdiction over the project (including, but not limited to the general plan, specific plan, local coastal program, or zoning ordinance) adopted for the purpose of avoiding or mitigating an environmental effect? c) Conflict with any applicable habitat conservation plan or natural community conservation plan? Discussion: O • O q• C iea O M FP q o • cE yI E' HaE ^ R ❑ 0 0 0 ❑ 0 0 0 ❑ - ❑ 0 p a) The project would not divide an established community. Three lanes on the bridge will be open to traffic during bridge reconstruction, one southbound and two northbound. Bridge reconstruction will last approximately 6 months. The reconstructed bridge will have the same number of lanes as the original bridge, 3 northbound lanes and 2 southbound lanes.[1,3,4] b) The project is consistent with the applicable land use plans, policies, and regulations of agencies that have jurisdiction over the project (e.g., City of San Mateo General Plan, City of San Mateo Zoning Code). [1,2,3,4] c) There are no habitat conservation plans or natural community plans applicable to the project site. [1,3,6] Initial Study 3-18 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3: CHECKLIST 3.10 Mineral Resources Would the project: a) Result in the loss of availability of a known mineral resource that would be of value to the region and the residents of the state? b) Result in the loss of availability of a locally -important mineral resource recovery site delineated on a local general plan, specific plan or other land use plan? 0 0 0 p 0 0 0 p Discussion: a) Known mineral resources do not exist on the project site. [1,5,6] b) Locally -important mineral resources do not exist on the project site. [1,5,6] San Mateo Creek Improvements Project 3-19 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3: CHECKLIST 3.11 Noise Would the project: a) Exposure of persons to or generation of noise levels in excess of standards established in the local general plan or noise ordinance, or applicable standards of other agencies? b) Exposure of persons to or generation of excessive groundborne vibration or groundborne noise levels? c) A substantial permanent increase in ambient noise levels in the project vicinity above levels existing without the project? d) A substantial temporary or periodic increase in ambient noise levels in the project vicinity above levels existing without the project? e) For a project located within an airport land use plan or, where such a plan has not been adopted, within two miles of a public airport or public use airport, would the project expose people residing or working in the project area to excessive noise levels? f) For a project within the vicinity of a private airstrip, would the project expose people residing or working in the project area to excessive noise levels? z ez O 0 0 0 ❑ 0 0 0 ❑ 0 0 0 ❑ 0 0 ❑ ❑ ❑ 0 ❑ O 0 ❑ E Discussion: a) The City of San Mateo General Plan states that day and night average noise levels in the project area range between 60 and 75 decibels (dBA). Construction equipment that will be used for the project range in noise levels between 70 and 95 dBA at 50 feet. The project would result in increases in noise levels during construction. These increases in noise levels would be variable and short-term in nature, approximately 6 months. The following mitigation measure would be implemented to reduce noise impacts to less than significant levels. MM -13 Construction hours will be limited to Monday through Friday from 8am to 5pm. Mufflers will be maintained on construction equipment. [1,3,4,12] b) No substantial ground vibrations would be created by the project during the construction of concrete levee walls and the reconstruction of the Norfolk Street Bridge. Pile drivers will not be used during bridge reconstruction. Construction impacts would be short-term and temporary. [3,4] Initial Study 3-20 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3: CHECKLIST c) The project would not result in a substantial permanent increase in ambient noise levels due to its nature as a flood control improvement project. [3,4] d) The project would result in temporary, but not substantial, increases in ambient noise levels in the project vicinity during construction. After project construction, noise levels in the area would return to previous levels. [1,3,4,12] e) The project site is located approximately 5 miles south of the San Francisco International Airport. Airplanes occasionally fly over the project area producing increases in noise levels. These levels are not high enough to impact human health in the project area. The project would not expose people to long-term excessive noise levels. [3,4] f) The project site is not located within the vicinity of a private airstrip. [3,4] San Mateo Creek Improvements Project 3-21 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3: CHECKLIST 3.12 Population and Housing Would the project: a) Induce substantial population growth in an area, either directly (for example, by proposing new homes and businesses) or indirectly (for example, through extension of roads or other infrastructure)? b) Displace substantial numbers of existing housing, necessitating the construction of replacement housing elsewhere? c) Displace substantial numbers of people, necessitating the construct -ion of replacement housing elsewhere? Discussion: C o e C O.V; IF: G C V V C q mi A b V% r, i s E 2;'� °' C fi z E o .m— u °� o d m., C. VI ', N1 '9 c .J <A 3'^ 0 0 0 0 0 0 0 El 0 0 E a) The project would not induce population growth in the project vicinity. [3,4] b) The project would not displace existing housing. [3,4] c) The project would not displace people. [3,4] Initial Study 3-22 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3: CHECKLIST 3.13 Public Services Would the project: Result in substantial adverse physical impacts associated with the provision of new or physically altered governmental facilities, need for new or physically altered governmental facilities, the construction of which could cause significant environmental impacts, in order to maintain acceptable service ratios; response times or other performance objectives for any of the public services: a) Fire protection? b) Police protection? c) Schools? d) Parks? e) Other public facilities? T O Ct' *.- G G Cme:_ V n OO 2 V v n E— o E- ;, a 010- cd . Vj 'VI 't., G 'i%J .94 ❑ 0 0 0 O 0 0 0 ❑ 0 0 E ❑ 0 0 0 ❑ 0 0 E Discussion: a) The project would not increase the demand for fire protection because it involves flood control improvements. A fire access road exists on the north side levee along San Mateo Creek. Construction of the concrete wall on this section of the levee will not result in reduction in the size of the fire access road below the required width. During construction, the fire access road would be used as a staging area. Section 3.7 Hazards and Hazardous Materials, MM -12 will ensure that impacts to fire access are less than significant. [3,4] b) The project would not substantially increase the demand for police protection because it does not introduce a new permanent population or commercial facility that increase the need for police protection. [3,4] c) The project would not increase the population in the project vicinity. Therefore, no new schools will be required. [3,4] d) The project would not require physical improvements to parks in the project vicinity. [3,4] e) The project would not require physical improvements to any other public facilities off - site. [3,4] San Mateo Creek Improvements Project 3-23 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3: CHECKLIST 3.14 Recreation Would the project: a) Increase the use of existing neighborhood and regional parks or other recreational facilities such that substantial physical deterioration of the facility would occur or be accelerated? Does the project: b) Include recreational facilities or require the construction or expansion of recreational facilities which might have an adverse physical effect on the environment? . A 1 V0. R 4 :0° n 3 A {l b E. G •2.., E °i ' ° a ' E C D..n U�' b ,0 E 3— ❑ 0 2 0 0 0 p 0 Discussion: a) The project would include a new bicycle lane on the Norfolk Street Bridge that would extend the existing bicycle lane on Norfolk Street. The project would be located adjacent to an existing trail that runs along the north side of San Mateo Creek from J. Hart Clinton Drive and Norfolk Street. The addition of the bicycle lane would not result in the substantial physical deterioration of existing neighborhood and regional parks or other recreational facilities. [1,3,4] b) The project does not include recreational facilities or require the construction or expansion of recreational facilities. [1,3,4] Initial Study 3-24 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3: CHECKLIST 3.15 Transportation/Traffic Would the project: a) Cause an increase in traffic which is substantial in relation to the existing traffic load and capacity of the street system (i.e., result in a substantial increase in either the number of vehicle trips, the volume to capacity ratio on roads, or congestion at intersections)? b) Exceed, either individually or cumulatively, a level of service standard established by the county congestion management agency for designated roads or highways? c) Result in a change in air traffic patterns, including either an increase in traffic levels or a change in location that results in substantial safety risks? d) Substantially increase hazards due to a design feature (e.g., sharp curves or dangerous intersections) or incompatible uses (e.g., farm equipment)? e) Result in inadequate emergency access? f) Result in inadequate parking capacity? g) Conflict with adopted policies, plans, or programs supporting alternative transportation (e.g., bus turnouts, bicycle racks)? Discussion: O 0 p 0 ❑ 0 0 ❑ ❑ ❑ 0 ❑ 0 0 0 ❑ 0 0 p O 0 0 p ❑ 0 0 p a) Norfolk Street is an arterial roadway. Construction will be staged to minimize impacts to traffic. During the Norfolk Street Bridge reconstruction, the median island will be taken out and traffic will be shifted to one half of the bridge, with one southbound lane and two northbound lanes. The deck on the other half of the bridge will be demolished and reconstructed to include the raising and extension of the bridge and the approaches will be built up. Next, the traffic will be shifted to the newly constructed side and the deck on the other side will be demolished and rebuilt. Construction is estimated to last 6 months. Impacts to traffic will be short-term because the new bridge will have the same number of lanes as the current bridge (i.e., three northbound lanes, two southbound lanes). It is estimated that 5 to 10 construction workers will be required and will not significantly impact traffic in the project area. The project will not cause substantial increases in traffic during or after construction and will have a less than significant impact to traffic. [1,3,4] b) The reconstruction of the Norfolk Street Bridge will be staged to minimize traffic impacts and congestion during the six month construction phase of the project. San Mateo Creek Improvements Project 3-25 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 g) 3: CHECKLIST Norfolk Street is an arterial roadway and after the reconstruction of the bridge it will return to its current level of service. [1,3,4] c) The project would not add or reduce air traffic or change air traffic patterns. [3,4] d) The bottom elevation of the Norfolk Street Bridge deck will be raised approximately 1 foot. The approaches to Norfolk Street will be reconstructed to accommodate the new bridge profile. [3,4] e) The project would not result in inadequate emergency access in the project vicinity. Construction will be staged to minimize traffic impacts. [3,4] f) A few parking spaces exist on the southbound side of the Norfolk Street Bridge and will be removed during the bridge reconstruction. The project will not require parking. Removal of the spaces on the bridge will not result in a significant impact to parking capacities in the project vicinity. [3,4] The project would support alternative modes of transportation by adding a bicycle lane over the Norfolk Street Bridge. The project would not conflict with adopted policies, plans, or programs supporting alternative transportation. [1,3,4] Initial Study 3-26 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 g) 3: CHECKLIST 3.16 Utilities and Service Systems Would the project: a) Exceed wastewater treatment requirements of the applicable Regional Water Quality Control Board? b) Require or result in the construction of new water or wastewater treatment facilities or expansion of existing facilities, the construction of which could cause significant environmental effects? c) Require or result in the construction of new storm water drainage facilities or expansion of existing facilities, the construction of which could cause significant environmental effects? d) Have sufficient water supplies available to serve the project from existing entitlements and resources, or are new or expanded entitlements needed? e) Result in a determination by the wastewater treatment provider which serves or may serve the project that it has adequate capacity to serve the project's projected demand in addition to the provider's existing commitments? f) Be served by a landfill with sufficient permitted capacity to accommodate the project's solid waste disposal needs? Comply with federal, state, and local statutes and regulations related to solid waste? Discussion: ❑ ❑ 0 E O 0 0 El O 0 0 E ❑ 0 0 0 ❑ ❑ ❑ E ❑ 0 E 0 O 0 p 0 a) The project would not require wastewater treatment services during operation. Construction employees will use temporary toilets, which will be removed after construction. [3,4] b) The project would not require or result in the construction or expansion of water or wastewater treatment facilities due to its nature as a flood control improvement project. [3,4] c) The project will not substantially increase impervious surfaces and will not require or result in the construction of new storm water drainage facilities or expansion of existing facilities. The project would be beneficial for storm water drainage in the project area. The existing facilities downstream are adequate to accommodate the flow contained by the levee walls. [3,4] San Mateo Creek Improvements Project 3.29 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 g) 3: CHECKLIST d) Existing water supplies would be adequate enough to serve project needs during construction. Project water demand after construction is expected to be minimal. No new entitlements would be required. [3,4] e) The project would have no effect on the current capacity of the wastewater treatment provider because it will not generate substantial effluent flows. [3,4] f) During the construction phase of the project, solid waste would mostly consist of the demolished bridge deck. The landfill that would serve the project possesses sufficient permitted capacity to accommodate the project's construction solid waste disposal needs. [3,4,8] The project would not produce substantial amounts of solid waste. The project would comply with federal, state, and local statutes and regulations related to solid waste. San Mateo County's Integrated Waste Management Plan, Source Reduction and Recycling Element requires the recycling and reduction of solid waste. To comply with the Plan the following measure is recommended. Recommended Measure The solid waste that is produced during construction shall be recycled, if feasible. [1,3,4,6,8] Initial Study 3-28 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3: CHECKLIST 3.17 Mandatory Findings of Significance Does the project: a) Have the potential to degrade the quality of the environment, substantially reduce the habitat of a fish or wildlife species, cause a fish or wildlife population to drop below self-sustaining levels, threaten to eliminate a plant or animal community, reduce the number or restrict the range of a rare or endangered plant or animal or eliminate importantexamples of the major periods of California history or prehistory? b) Have impacts that are individually limited, but cumulatively considerable? ("Cumulatively considerable" means that the incremental effects of a project are considerable when viewed in connection with the effects of past projects, the effects of other current projects, and the effects of probable future projects)? c) Have environmental effects which will cause substantial adverse effects on human beings, either directly or indirectly? 0 0 R 0 0 0 0 0 0 p Discussion: a) During bridge reconstruction and concrete apron construction, approximately 4 months, water will be diverted away from the construction zone in San Mateo Creek using cofferdams. Pipe(s) will connect the cofferdams to allow the creek water to flow through the construction zone and will allow fish, such as endangered steelhead trout, to pass through the de -watered area. Water diversion shall take place when steelhead trout spawning migration does not typically occur. After construction, the cofferdams will be removed and the creek will be returned to its previous course. The project area is surrounded by intense residential and commercial development and construction of the concrete levee walls would not significantly restrict the movement of wildlife. A maximum of five gumplants, special -status species, will be removed during bridge reconstruction. This removal will not have a substantial adverse effect because the species is common in the project area and readily recolonizes disturbed areas adjacent to tidal brackish marsh. The project will result in temporary but less than significant impacts to the environment. [3,4,6,9,13] b) Project impacts after the implementation of mitigation will be less than significant and should be regarded as di minimis. Therefore, adding the project impacts to past, current, and future projects would not result in cumulatively considerable impacts. [3,4,9] San Mateo Creek Improvements Project 3-29 November 12, 1999 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3: CHECKLIST c) The project has,a beneficial effect on human beings by improving flood control for 100 - year tidal or storm event in the vicinity of San Mateo Creek east of Highway 101. [3,4] Initial Study 3-30 November 12, 1999 1 3: CHECKLIST 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3.18 Sources The following sources were used in the analysis and were referenced in the sections by number. 1) City of San Mateo. 1990. Vision 2010, The San Mateo General Plan. 2) City of San Mateo. 1998. City of San Mateo Zoning Code. 3) Project Plans. 4) MHA Site Visits and Analysis. 5) California Department of Conservation, Division of Mines and Geology. 1990. Geologic Map of the San Francisco — San Jose Quadrangle. 6) County of San Mateo. 1986. County of San Mateo General Plan. 7) Environmental Services Agency, Planning and Building Division, San Mateo County. 1998. San Mateo County Local Coastal Program Policies 1998 Update. 8) Environmental Science Associates. 1999. San Mateo County Integrated Waste Management Plan, Siting Element. 9) 2M Associates. 1999. Shoreline Parks Master Plan, Research and Analysis Report. 10) Bay Area Air Quality Management District. 1997. Bay Area '97 Clean Air Plan. 11) Bay Area Air Quality Management District. 1999. Bay Area Attainment Status as of April 1999. 12) Magrab, Edward B. 1975. Environmental Noise Control, John Wiley & Sons, New York. (Adapted by Wilson, Ihrig & Associates, Inc. 1986) 13) Harvey and Stanley Associates, Inc. 1989. Vegetation, Fisheries and Wildlife Components - Environmental Impact Report, Third Avenue/101 Interchange Widening 14) Parikh Consultants, Inc. 1999. Geotechnical Engineering Investigation Report Flood Wall Design & Norfolk Street Bridge Modifications Along San Mateo Creek from Route 101 to J. Hart Clinton Drive, City of San Mateo, California. 15) California Historical Resources Information System. 1999. Northwest Information Center, Sonoma State University, California. 16) Dr. Steve Granholm. 1999. Principal-in-Charge/Wildlife Biologist, LSA Associates, Inc. Personal communication. San Mateo Creek Improvements Project 3-31 November 12, 1999 1 EN a : at .u. im IMP INN i =II 11•1 INN