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7C <br /> Page 58 <br /> E. Corrosive Soils <br /> Po#ential Impact 11-5: The soil on the praject site is classified as "severely <br /> corrosive" to iron, steel, metal, and concrete. This condition could result in long-term damage to <br /> building foundations and underground utifity systems, a possibility that represents a pofenfially <br /> signi�canf rmpact. <br /> Mitigation 1'�-5: Require that the detailed, design-{evei geotechnical <br /> investigations recommended under Mitigations 19-9 and 91-2 include an evaluation of corrosive <br /> soils within the limits of all foundation and utility construction. Wherever corrnsive soiEs are <br /> found in sufficien# concentrations, recommendations shall be made to protect iron, steel, metal, <br /> and concrete from long-term deterioratinn caused by contact with corrosive on-s'tte soils. in <br /> general, these recommendations are expected to include, but nat be fimited to, the foflowing <br /> provisions: <br /> 1. Protect buried iron, steel, cast iron, ductile iron, galvanized steel, and <br /> dielectric coated steel or iron (including a!I buriecf inetallic pressure piping) <br /> against corrosion from soil. <br /> 2. Protecf buried metal and cement structures in contact with earth surfaces <br /> from chloride ion concentrations. <br /> 3. Use sulfate-resistant concrete mix for all concrete in contact with the ground, <br /> including piles, pile caps, and grade beams. <br /> 4. Consult a corrosion expert during the prnject's detailed design phase to he[p <br /> design the most effective corrosion protection. <br /> Findings: Implementation of this measure would reduce this potential to a less- <br /> than-significant level. <br /> F. Soil Erosion ancf Sedimentation <br /> Potenfial Impact 11-6: Project development would disturb the site's natural <br /> topography and vegetative cover, leaving soils expased to wind and water erasion during the <br /> construction period. Eroded soils would be washed either directly inta Redwood Creek, or the <br /> former PenEnsula Marina, or inta on-site drainage facElities, which drain infia these same water <br /> bodies. Resulting sedimentation coufd affect the flows of Redwoad Creek and Smith Slough, <br /> increasing flooding potential and maintenance problems. In addifion, suspended seciiment <br /> would degrade water quaiiiy in the creek, siough, and marinas by increasing turbidity. These <br /> possib[e e�'ects af sail erosion represent a pofenfially signifcant impact. <br /> Mitigation 11-6: Require that the applicant prepare an erosion contrpl plan <br /> subject to City approval and consistent with the required project Stormwater Pollutian <br /> Prevention Plan (SWPPP) (see Mifigafion 9-�). Implement the plan during cons#ruction. <br /> Erosion during all phases of construction shall be control{ed through the use of erosion and soil <br /> transport cantro! facilities. These shali include the use of catch basins and fi{ter fabrics, and the <br /> directian of stormwater runoff away from disturbed areas. The plan shall also provide for long- <br /> term stabilization and maintenance of remaining exposed soils after construction is campleted. <br /> Areas disturbed by construction shaif be either covered with imperviaus surfaces (e.g., buildings <br /> and pavement) or fully stabiiized with landscaping and/or native vegetation. All revegetated <br /> AttylReso/Reso.1772 37 <br /> 12i307 <br />