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12/1 7/2007 E. Corrosive Soils Potential Impact 11-5: The soil on the project site is classified as "severely corrosive" to iron, steel, metal, and concrete. This condition could result in long-term damage to building foundations and underground utility systems, a possibility that represents a potentially significant impact. Mitigation 11-5: Require that the detailed, design-level geotechnical investigations recommended under Mitigations 11-1 and 11-2 include an evaluation of corrosive soils within the limits of all foundation and utility construction. Wherever corrosive soils are found in sufficient concentrations, recommendations shall be made to protect iron, steel, metal, and concrete from long-term deterioration caused by contact with corrosive on-site soils. In general, these recommendations are expected to include, but not be limited to, the following provisions: 1. Protect buried iron, steel, cast iron, ductile iron, galvanized steel, and dielectric coated steel or iron (including all buried metallic pressure piping) against corrosion from soil. 2. Protect buried metal and cement structures in contact with earth surfaces from chloride ion concentrations. 3. Use sulfate-resistant concrete mix for all concrete in contact with the ground, including piles, pile caps, and grade beams. 4. Consult a corrosion expert during the project's detailed design phase to help design the most effective corrosion protection. Findings: Implementation of this measure would reduce this potential to a less- than-significant level. F. Soil Erosion and Sedimentation Potential Impact 11-6: Project development would disturb the site's natural topography and vegetative cover, leaving soils exposed to wind and water erosion during the construction period. Eroded soils would be washed either directly into Redwood Creek, or the former Peninsula Marina, or into on-site drainage facilities, which drain into these same water bodies. Resulting sedimentation could affect the flows of Redwood Creek and Smith Slough, increasing flooding potential and maintenance problems. In addition, suspended sediment . would degrade water quality in the creek, slough, and marinas by increasing turbidity. These possible effects of soil erosion represent a potentially significant impact. Mitigation 11-6: Require that the applicant prepare an erosion control plan subject to City approval and consistent with the required project Stormwater Pollution Prevention Plan (SWPPP) (see Mitigation 9-1). Implement the plan during construction. Erosion during all phases of construction shall be controlled through the use of erosion and soil transport control facilities. These shall include the use of catch basins and filter fabrics, and the direction of stormwater runoff away from disturbed areas. The plan shall also provide for long- term stabilization and maintenance of remaining exposed soils after construction is completed. Areas disturbed by construction shall be either covered with impervious surfaces (e.g., buildings and pavement) or fully stabilized with landscaping and/or native vegetation. All revegetated Atty/Reso/~eso.1772 121707 37 14829 Muff# 613