3B Public Hearing 2009 0720 - Laserfiche WebLink

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d. Be located on expansive soil, creating substantial POTENTIALLY 5, 6, 7 ISSUES POTENTIALLY SIGNIFICANT LESS THAN NO e. Have soils capable of adequately supporting the SIGNIFICANT UNLESS SIGNIFICANT- IMPACT SOURCES use of septic tanks or alternative waste water ISSUES MITIGATION IMPACT disposal systems where sewers are not available INCORPORATED d. Be located on expansive soil, creating substantial X 5, 6, 7 risks of life or property? e. Have soils capable of adequately supporting the X 5, 6, 7 use of septic tanks or alternative waste water disposal systems where sewers are not available for the disposal of waste water? f Any increase in wind or water erosion of soils, X 4, 5, 8 either on- or off-site? g. Changes in deposition or erosion of beach, sands, X 4, 5,_8 or changes in siltation, deposition or erosion which may modify the channel of a river or stream or the bed of the ocean or any bay, inlet or lake? EXPLANATION: a) i. The Alquist-Priolo Earthquake Fault Zoning Act requires the delineation of zones along sufficiently active and well defined faults by the California Department of Conservation, Geological Survey (CGS). The project site is not within an Earthquake Fault Zone, as defined by the Alquist-Priolo Earthquake Fault Zoning Act, and no known active or potentially active faults exist on the sites. The nearest active fault to the project sites are the Hayward fault, approximately 2.9 miles to the northeast; the Calaveras, approximately 17 miles to the northeast; and the San Andreas, approximately 26 miles to the southwest. Therefore, no fault rupture hazards are anticipated with project implementation. ii, iii. In 2002, the U.S. Geologic Survey (USGS) predicted a 62 percent probability of a magnitude 6.7 or greater earthquake occurring in the San Francisco Bay Area by the year 2032. During a major earthquake on a segment of one of the nearby faults, strong shaking is expected to occur at the project sites. The project sites are also within a designated liquefaction hazard zone. Strong shaking during an earthquake can result in ground failure such as that associated with soil liquefaction, lateral spreading and cyclic densification. Test borings and cone penetration tests were performed by Rockridge Geotechnical in August, 2008, and these results were used to evaluate the potential for seismic hazards to occur. Based on preliminary field investigations, potentially significant impacts could occur with geologic hazards associated with strong shaking on a nearby fault and the presence of compressible clay zones below the sites_ Therefore, mitigation of potential liquefaction hazards is required with project implementation_ Mitigation Measure #3: The City of San Leandro has incorporated the 2006 International Building Code into its municipal building code (Title 7, Chapter 7-5). The project applicant would be required to comply with all applicable State and City regulations to address potential geologic hazards associated with the proposed project, including ground shaking and liquefaction. Geotechnical and seismic design criteria must conform to engineering recommendations in accordance with the seismic requirements of the 2007 California Building Code (Title 24) and any amendments adopted in the San Leandro Municipal Code. Additionally, because the project site is in a liquefaction Seismic Hazard Zone, the project applicant will be required to comply with the guidelines set forth by California Geological Survey Special Publication 117. iv. The TOD Strategy Area is nearly flat and there are no hilly areas immediately adjacent to the project sites. Site 1 is rectangular in shape and currently consists of an at -grade asphalt parking lot. Site 1 elevations range between 44 and 47 feet, and the site is underlain by clay that extends to depths ranging from 25 to 50 feet below the existing ground surface (bgs). Site 2 consists of vacant, undeveloped land with site elevations ranging between 45 and 48 feet, and the site is blanketed by 22 to 28 feet of clay with varying sand content, with interbedded alluvial soils beneath the upper clay layer extending to a maximum depth of 100 feet bgs. Neither site is associated with significant slopes, and there are no adjacent hillsides. Therefore, the proposed project would not create potential impacts associated with landslides, mudflows or other mass soil movements. The proposed project would consist of grading and trenching activities that could create effects on water quality as a result of erosion. Because the project site exceeds one acre in size, the project applicant would be required to apply for coverage under the State General Construction Permit in order to comply with federal National Pollutant Discharge Elimination Cornerstone at San Leandro Crossings Initial Study 5 March 2009