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Including additional storage by replacing the existing storm drain line within Maple Street with a new 48 -inch storm drain line or larger from US 101 up to and including the tide gate at Redwood Creek to account for tide gate operation of the existing outfall, as determined by the Engineering and Transportation Division. The detailed hydraulic evaluations and proposed changes to the project designs, if necessary, shall be submitted to the City and any other regulatory agencies that have jurisdiction over the improvements prior to the issuance of a grading permit. Finding: Implementation of Mitigation Measure HYD -2 would reduce project -related impacts to the depth and velocity of flood flows along the existing banks of Redwood Creek, potentially resulting in erosion and siltation, to a less -than -significant level. Facts in Su000rt of Finding: This mitigation measure appropriately identifies the need for hydraulic evaluations for improvements within 100 -year flood zones, as well as modifications consistent with best management practices to reduce potential flooding and erosion impacts. Impact HYD -3: Placement of engineered fill to raise the elevation of the project site and placement of surcharge materials would alter existing drainage patterns which could result in flooding of off-site areas during construction of the proposed project and the project variant. Mitigation HYD -3: The project applicant shall prepare a Construction Period Stormwater Drainage Control Plan which shall be submitted to the City for review and approved prior to the issuance of a grading permit. The Construction Period Stormwater Drainage Control Plan shall include figures depicting the proposed grading of engineered fill and surcharge stockpiles and describe construction period drainage control systems (e.g., temporary berms and swales). The plan shall also include detailed hydraulic evaluations of stormwater runoff patterns, including surface runoff flow directions, flow lines within the temporary drainage control systems, and estimated discharge rates and volumes for all site grading and surcharging stages. The proposed grading and temporary drainage control systems shall be designed such that the estimated rates and volumes of surface runoff discharge to existing off-site stormwater drainage systems would not increase beyond the existing condition. If rates and volumes of surface runoff discharge to existing off-site stormwater drainage systems would increase beyond the existing condition, the Construction Period Stormwater Drainage Control Plan shall demonstrate that the existing off-site stormwater drainage systems have capacity to convey the increased discharge. Finding: Implementation of Mitigation Measure HYD -3 would reduce potential project -related impacts to the alteration of existing drainage patterns to a less -than -significant level. Facts in SUDDort of Findina: This mitigation measure appropriately identifies the requirement for a Construction Period Stormwater Drainage Control Plan to be reviewed and approved by the City, as well as specific hydraulic evaluations to be included in the plan demonstrating that the existing off-site stormwater drainage systems would have the capacity to convey the increased discharge. Impact HYD -4: The proposed project and the project variant would result in the alteration of the existing drainage pattern which could contribute to flooding on- and off-site during operation of the project. ATTY/RESO.0035/CC RESO CERTIFYING FINAL EIR-1548 MAPLE RESO. NO. 15661 REV: 04-30-18 PR MUFF NO. 601 Page 20 of 49