AgdaPkt 2017-01-09 Closed and Joint

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f W TA. - Page 75 a stream or river; therefore, no associated impacts would occur with respect to substantial erosion or siltation on - or off-site. Moreover; the proposed project would not substantially alter the existing drainage pattern of the site so as to substantially increase the rate or amount of surface runoff in a manner which would result in flooding on- or off-site. The DTPP program EIR (pp. 10-23 and 10-24) concluded that DTPP facilitated development would not result in any significant storm drainage impacts. The proposed project is in compliance with all applicable DTPP standards. Also, the City's Drainage Guidelines for Commercial Development require post -development storm water discharge to be equal to or less than pre -development discharge; the City also mandates that proposed site conditions maintain the same runoff for the 30 year storm event as compared to the existing 10 year event. The project would be subject to these requirements as conditions of project approval. As a result of DTPP standards and City requirements, storm drainage impacts would be less than significant. Also see item (a) above. Redwood Creek flows underground in a box culvert east of the project site, under a surface parking lot (Google Maps, accessed 2122116). The box culvert would not be disturbed or altered by project construction or operation. Originally, Redwood Creek crossed the northeast corner of the project site, approximately where the entrance to the existing Bradford Street driveway is located, before curving to the southeast and continuing across the property line to the adjacent school district property. Then the creek channel was undergrounded in a culvert in the late 1950s/early 1960s, and later in the 1960s the culvert was filled in when the configuration of Redwood Creek was realigned to the east. The current Redwood Creek channel surfaces from this realigned underground culvert approximately 210 feet northeast of the project site, near Bradford Street and Main Street, where the creek is daylighted. With implementation of the San Mateo Countywide Stormwater Pollution Prevention Plan (SWPPP) and the Redwood City Stormwater Management and Discharge Control Program (Municipal Code Chapter 27A), as part of both the NPDES permit program and DTPP program EIR Mitigation 16-3, project construction would result in a less -than -significant degradation of existing water quality. In addition, as a standard condition of project approval, the City would require the project applicant to implement a winterization program to minimize the potential for erosion and sedimentation if construction is not completed by the start of the wet season. Furthermore, operation of the proposed project (a residential building with a commercial component) would not generate any foreseen uses that would substantially degrade water quality. The proposed project is in compliance with all applicable DTPP standards, and as a result, no additional water quality impacts are anticipated with project implementation. Also see item (a) above. & h. The project site is not currently located in a Special Flood Hazard Area as defined by the Federal Emergency Management Agency (FEMA) National Flood Insurance Program (NFIP), which means that the site is not currently identified as subject to extensive damage from a one percent chance (100 year) flood. The entire project site is located in Zone X (Other Flood Areas) on its FEMA Flood Insurance Rate Map (FIRM), which includes "areas of 0.2% annual chance [500-year/flood; areas of 1% annual chance [100-year/flood with average depths of less than I foot or with drainage areas less than I square mile; and areas protected by levees from I % annual chance flood" (FEMA FIRM Map Number 06081 C0301E, Panel 301 of 510, Effective Date October 16, 2012). Any standard City requirements for flood protection in conformance with the NFIP would ensure that potential impacts from flooding would be less than significant. In August 2015, the Federal Emergency Management Agency (FEMA) issued new preliminary Flood Insurance Rate Maps (FIRM) for the City of Redwood City. According to the new preliminary FIRMfor the City of Redwood City, the entire project site is located in Zone AE (EL 10), which is designated a "Special Flood Hazard Area. " As a condition of project approval, the City would require new construction and substantial improvements to existing structures to set the lowest first floor elevation (FFE) at or above (one foot recommended) the base flood elevation. Although this would not be required if construction starts prior to adoption of the FIRM revisions, the project may still be subject to FEMA flood insurance requirements based on the elevation certificate filed upon completion of the project. The City recommends that the applicant design the FFE and any floodproofrng to accommodate the proposed new base flood elevation, and consider implications to future flood insurance requirements. As noted in items (c) and (d) above, Redwood Creek flows underground in a box culvert east of the project site, under a surface parking lot. On the FIRM, the culvert is identified as Zone A: "I% annual chance, flood discharge contained in channel, " which means that the underground culvert would contain a 100 year flood. As explained above, originally Redwood Creek crossed the northeast corner of the project site, approximately where the entrance to the existing Bradford Street driveway is located, before curving to the southeast and continuing across the property line to the adjacent school district property. Then the creek channel was undergrounded in a culvert in the late 1950s/early 1960s, and later in the 1960s the culvert was filled in when the configuration of Redwood Creek was realigned to the east. The current Redwood Creek channel surfaces from this realigned underground culvert approximately 210 feet northeast of the project site, near Bradford Street and Main Street, where the creek is daylighted. 28