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Geology/Soils (Continued)
<br />System (NPDES) requirements, in accordance with the State Water Resources Control Board (see Section VIII, Hydrology
<br />and Water Quality).
<br />The applicant would be required to develop and implement a Storm Water Prevention Plan (SWPPP) to reduce potential
<br />erosion and subsequent sedimentation of storm water runoff. The SWPPP would include Best Management Practices
<br />(BMPs) to control erosion associated with grading, trenching and other ground surface disturbance. Additionally, all
<br />construction activities will be required to comply with Chapter 18 of the San Leandro Municipal Code regulating
<br />excavation activities and the construction of foundations and retaining walls, as well as the San Leandro Grading
<br />Ordinance regulating grading activities, drainage and erosion control Therefore, compliance with the NPDES permit
<br />process and the California Building Code requirements would minimize potential impacts from erosion during and after
<br />project construction and would ensure that potential geology and soils impacts are less than significant.
<br />c- e)Borings, cone penetration tests and laboratory testing conducted by Rockridge Geotechnical (December 22, 2008) revealed
<br />potentially liquefiable soil at a depth of between 42 and 50 feet on Site 1, with estimates that ground -surface settlement
<br />associated with liquefaction after a major seismic event is less than '4 inch over a horizontal distance of 30 feet. Site 2
<br />demonstrated potentially liquefiable soil layers at depths ranging from 23 to 96 feet bgs indicating that settlement resulting
<br />from post -liquefaction reconsolidation could be up to 1 —1 '/4 inches, and differential settlement may be up to '/z inch over a
<br />horizontal distance of 30 feet. An acceptable degree of soil stability would be achieved for expansive, liquefaction -prone
<br />and compressible soils by incorporating soil treatment programs such as replacement, grouting, compaction and drainage
<br />control during the excavation and construction phases of the project in order to address site-specific soil conditions. No
<br />septic tanks or leach field systems are proposed as part of the project, but rather wastewater disposal would be handled
<br />through the sanitary sewer system.
<br />Mitigation Measure #4: Where wet and/or subgrade soils are encountered during subgrade preparation or other
<br />grading activities, the weak soil shall be removed and replaced with select fill in compliance with the compaction
<br />and other requirements set forth in the Final Geotechnical Report (Rockridge Geotechnical, January 21, 2009).
<br />Ground modification techniques, such as permeation grouting, columnar jet grouting, deep soil mixing, stone
<br />columns, gravel or other drains shall be implemented, and deep foundations shall be put in place to mitigate
<br />potential liquefaction -induced settlement impacts.
<br />f-g)Development and intensification of the project site could result in wind or water erosion of soils on- or off-site, as
<br />underutilized and vacant parcels are replaced with high-density residential development and a BART parking structure. To
<br />ensure that impacts are less than significant, the project applicant will be required to adhere to Best Management Practices.
<br />All construction activities will be required to comply with Chapter 18 of the San Leandro Municipal Code regulating
<br />excavation activities and the construction of foundations and retaining walls, as well as the San Leandro Grading
<br />Ordinance regulating grading activities, drainage and erosion control. Therefore, compliance with the NPDES permit
<br />process and the California Building Code requirements would minimize potential impacts from erosion during and after
<br />project construction and would ensure that potential geology and soils impacts are less than significant. The proposed
<br />development will not result in significant amounts of deposition or erosion of beach sands, or changes in siltation,
<br />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,
<br />as there are no bodies of water on or near the project site.
<br />There are no new impacts beyond what was analyzed in the Downtown San Leandro TOD Strategy EIR that was certified in
<br />2007-
<br />4. HYDROLOGY AND WATER QUALITY. Would-th'eproject:
<br />a. Violate any water quality standards or waste X 4, 5, 8
<br />discharge requirements?
<br />Cornerstone at San Leandro Crossings Initial Study 6 March 2009
<br />POTENTIALLY
<br />ISSUES
<br />POTENTIALLY
<br />SIGNIFICANT
<br />LESS THAN
<br />NO
<br />SIGNIFICANT
<br />UNLESS
<br />SIGNIFICANT
<br />IMPACT
<br />SOURCES
<br />ISSUES
<br />MITIGATION
<br />IMPACT
<br />INCORPORATED
<br />Geology/Soils (Continued)
<br />System (NPDES) requirements, in accordance with the State Water Resources Control Board (see Section VIII, Hydrology
<br />and Water Quality).
<br />The applicant would be required to develop and implement a Storm Water Prevention Plan (SWPPP) to reduce potential
<br />erosion and subsequent sedimentation of storm water runoff. The SWPPP would include Best Management Practices
<br />(BMPs) to control erosion associated with grading, trenching and other ground surface disturbance. Additionally, all
<br />construction activities will be required to comply with Chapter 18 of the San Leandro Municipal Code regulating
<br />excavation activities and the construction of foundations and retaining walls, as well as the San Leandro Grading
<br />Ordinance regulating grading activities, drainage and erosion control Therefore, compliance with the NPDES permit
<br />process and the California Building Code requirements would minimize potential impacts from erosion during and after
<br />project construction and would ensure that potential geology and soils impacts are less than significant.
<br />c- e)Borings, cone penetration tests and laboratory testing conducted by Rockridge Geotechnical (December 22, 2008) revealed
<br />potentially liquefiable soil at a depth of between 42 and 50 feet on Site 1, with estimates that ground -surface settlement
<br />associated with liquefaction after a major seismic event is less than '4 inch over a horizontal distance of 30 feet. Site 2
<br />demonstrated potentially liquefiable soil layers at depths ranging from 23 to 96 feet bgs indicating that settlement resulting
<br />from post -liquefaction reconsolidation could be up to 1 —1 '/4 inches, and differential settlement may be up to '/z inch over a
<br />horizontal distance of 30 feet. An acceptable degree of soil stability would be achieved for expansive, liquefaction -prone
<br />and compressible soils by incorporating soil treatment programs such as replacement, grouting, compaction and drainage
<br />control during the excavation and construction phases of the project in order to address site-specific soil conditions. No
<br />septic tanks or leach field systems are proposed as part of the project, but rather wastewater disposal would be handled
<br />through the sanitary sewer system.
<br />Mitigation Measure #4: Where wet and/or subgrade soils are encountered during subgrade preparation or other
<br />grading activities, the weak soil shall be removed and replaced with select fill in compliance with the compaction
<br />and other requirements set forth in the Final Geotechnical Report (Rockridge Geotechnical, January 21, 2009).
<br />Ground modification techniques, such as permeation grouting, columnar jet grouting, deep soil mixing, stone
<br />columns, gravel or other drains shall be implemented, and deep foundations shall be put in place to mitigate
<br />potential liquefaction -induced settlement impacts.
<br />f-g)Development and intensification of the project site could result in wind or water erosion of soils on- or off-site, as
<br />underutilized and vacant parcels are replaced with high-density residential development and a BART parking structure. To
<br />ensure that impacts are less than significant, the project applicant will be required to adhere to Best Management Practices.
<br />All construction activities will be required to comply with Chapter 18 of the San Leandro Municipal Code regulating
<br />excavation activities and the construction of foundations and retaining walls, as well as the San Leandro Grading
<br />Ordinance regulating grading activities, drainage and erosion control. Therefore, compliance with the NPDES permit
<br />process and the California Building Code requirements would minimize potential impacts from erosion during and after
<br />project construction and would ensure that potential geology and soils impacts are less than significant. The proposed
<br />development will not result in significant amounts of deposition or erosion of beach sands, or changes in siltation,
<br />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,
<br />as there are no bodies of water on or near the project site.
<br />There are no new impacts beyond what was analyzed in the Downtown San Leandro TOD Strategy EIR that was certified in
<br />2007-
<br />4. HYDROLOGY AND WATER QUALITY. Would-th'eproject:
<br />a. Violate any water quality standards or waste X 4, 5, 8
<br />discharge requirements?
<br />Cornerstone at San Leandro Crossings Initial Study 6 March 2009
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