Reso PC16-23 PC 0116 Reso CEQA - Sandpiper

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Sections 4.0 — Environmental Setting and Discussion of Impacts 49.3.2 Groundwater Impacts (Checklist Question 2) Groundwater beneath the project site occurs 4.5 to seven feet bgs, with tidal and seasonal fluctuations, Excavation for the project would be minimal, consisting of surface grading and setting of foundations. The project does not propose any wells, and would not otherwise come in contact with the groundwater beneath the site. The project footprint is relatively small and would add approximately 708 sf of pervious surfaces to the school campus. The project, therefore, would not impact the duality of groundwater beneath the site, deplete groundwater supplies, or substantially interfere with groundwater recharge, (Less Than Significant Impact) 4.9.3.3 Drainage Pattern Impacts (Checklist Questions 3 and 4) A portion of the stormwater runoff from the project site currently enters the Redwood Shores storm drain system, and the other portion discharges into the lagoon from an outfall at the rear of the property. Development of the proposed project would not substantially alter the existing drainage pattern of the site. The stormwater runoff generated by the project would be treated with LID treatment controls to the greatest extent feasible, in compliance with the MRP. The proposed LID treatment controls would reduce the rate and volume of stormwater runoff while also removing pollutants. For these reasons, the proposed project would not substantially alter drainage patterns resulting in erosion, sedimentation, or flooding downstream of the project site. (Less Than Significant Impact) 4.9.3.4 Flooding Impacts (Checklist Questions 7 —10) Redwood Shores is located on low-lying bayfront land surrounded by a levee system that protects Redwood Shores from high tides. Due to the protective levees, the project site is not mapped within a 100 -year floodplain. The site does, however, have the potential to flood as a result of levee overtopping or failure of the levee system. Current levee heights were constructed to withstand a I00 -year high tide. The crest of some levee reaches are at, or a few tenths of a foot lower than, the 100 -year tide elevation. Due to the short duration of that crest, however, flooding would be limited and shallow, provided that the levees do not fail from the overtopping. The City is currently undergoing a process to reaccredit the levees supporting the project area. In addition to the levee reaccreditation sought by the City, which would help to protect the project site and immediate project area from flooding and sea level rise, all construction, building setbacks, slopes, and grading proposed by the project would comply with the City of Redwood City's design requirement for a sea level rise of 36 inches by 2070. As a result, the finished additions and improvements would be above the 2070 sea level rise elevation. For these reasons, the proposed project would not place structures within a 100 -year flood hazard area or expose people or structures to significant risk as a result of levee or dam failure. The project site is not subject to inundation by seiches, tsunamis, or mudflows. The proposed project would not exacerbate existing flood hazards and, therefore, would not result in a significant impact under CEQA. (No Impact) City of Redwood City 62 Initial Study/Mitigated Negative Declaration Sandpiper Elementary School Facilities Expansion November 2016