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<br /> The project component site is located within a downtown urban setting, which is served by an existing storm drain
<br />system that outfalls into San Francisco Bay. The project component site is located within the Redwood Creek
<br />Watershed. Implementation of the proposed project component would utilize the existing stormwater conveyance
<br />facilities in Main Street and Broadway (the Broadway storm drain main connects to the Main Street storm drain main,
<br />with stormwater continuing to flow north before ultimately discharging in San Francisco Bay. In addition, as described
<br />in the Utility Report prepared for the applicant by Sandis (Sandis, “Utility Report, 1900 Broadway, Redwood City,
<br />California,” September 2023) as is required by Mitigation Measure UT-1d, there is a storm drain catch basin near
<br />Walnut Street and Spring Street that drains to Redwood Creek, which flows just north of the site. (Sandis, p. 1) Review
<br />of city maps and a site survey performed by Sandis indicate 12” storm drain laterals from catch basins on Broadway,
<br />Main Street, Walnut Street, and Marshall Street that connect to 48” mains running around the site perimeter along
<br />Broadway, most of Main Street, Walnut Street, and Marshall Street, converging to the manhole at the corner of
<br />Marshall Street and Main Street, draining north thereon. The remaining drainage for the existing project component
<br />site is provided by two storm drain catch basins located on Broadway, one catch basin on Main Street, one catch basin
<br />on Marshall Street, and three catch basins on Walnut Street (two of which are at the intersection of Walnut Street and
<br />Spring Street on either side of Spring Street and the third at the intersection of Walnut Street and Marshall Street), all
<br />of which ultimately converges via 48” mains to the same manhole on Marshall Street and Main Street. (Sandis, pp. 1,
<br />3-4; Plan Sheet TM2.0, 11/9/23), with stormwater continuing to flow north before ultimately discharging in San
<br />Francisco Bay).
<br /> The proposed project component would not contain uses that involve the discharge of cooled/heated water or pollutant-
<br />laden runoff. However, given the local urbanized area, the existing stormwater flows contain urban runoff with
<br />contaminants such as oil, grease, particulates, metals, and solvents. Because the proposed project is subject to the
<br />requirements of a National Pollutant Discharge Elimination System (NPDES) permit for municipal stormwater runoff
<br />and other requirements of the City, County, and Regional Water Quality Control Board, the conditions of which limit
<br />the volume of contaminants allowed to enter the storm drain system, the proposed project component would not violate
<br />any water quality standards or waste discharge requirements. Furthermore, the DTPP program EIR (pp. 10-23 through
<br />10-25) concluded that DTPP-facilitated development would not result in any significant water quality or stormwater
<br />drainage impacts. The proposed project component is in compliance with all applicable DTPP standards relevant to
<br />hydrology and water quality, and as a result, water quality and stormwater drainage impacts would be less than
<br />significant.
<br /> The City’s Drainage Guidelines for Commercial Development require post-development stormwater discharge to be
<br />equal to or less than pre-development discharge. Also, the City mandates that proposed site conditions maintain the
<br />same runoff for the 30-year storm event as compared to the existing 10-year event. As discussed above, stormwater
<br />runoff collected on the project component site currently drains to the City stormwater system; following treatment,
<br />per the City of Redwood City Stormwater Management and Discharge Control Program Ordinance (Redwood City
<br />Municipal Code Chapter 27A), stormwater from the project component would also continue to drain to the City
<br />stormwater system (Sandis, pp. 3-4; Plan Sheet TM5.0, 11/9/23). Project component approval requires that stormwater
<br />control measures be designed and sized to treat runoff from the entire project site using flow- or volume-based sizing
<br />criteria, subject to review and approval by the City and consistent with the San Francisco Bay Region Municipal
<br />Regional Stormwater NPDES Permit (MRP) Provision C.3.d.
<br /> The project is expected to qualify for a 75 percent reduction in LID stormwater treatment because the site is considered
<br />a larger infill project of the San Mateo Countywide Water Pollution Prevention Program (see “C.3 Regulated Projects
<br />Guide,” Appendix “J” – Special Project Category “B” (Larger Infill Projects). This means that the project would be
<br />75 percent exempt (in storm drainage volume) from County low impact development (LID) requirements because the
<br />project would: (1) be located in a municipality’s designated central business district, downtown core area or
<br />downtown core zoning district, neighborhood business district or comparable pedestrian-oriented commercial district,
<br />or historic preservation site and/or district; (2) create and/or replace more than 0.5 acres of impervious surface and
<br />less than 2.0 acres; (3) include no surface parking, except for incidental parking for emergency vehicle access, ADA
<br />access, and passenger or freight loading zones; (4) have at least 85 percent coverage of the entire site by permanent
<br />structures (the remaining 15 percent portion of the site may be used for safety access, parking structure entrances,
<br />trash and recycling service, utility access, pedestrian connections, public uses, landscaping and stormwater treatment);
<br />and (5) minimum density of either 50 dwelling units per acre (for residential projects) or a floor area ratio (FAR) of
<br />2:1 (for commercial projects) – mixed use projects may use either criterion. (Sandis, p. 2, and “Appendix D: C.3
<br />Development Review Checklist,” September 2023) However, according to the Utility Report, the project component
<br />would only seek a 39 percent reduction in LID stormwater treatment, because the project component proposes to use
<br />flow-through planters to treat 61 percent of runoff, which would be routed to the flow-through planters via storm drain
<br />piping. The remaining stormwater runoff would be treated by non-LID measures, specifically media filters located
<br />within the building. (Sandis, p. 2, and “Appendix F: LID Reduction Narrative,” September 2023) The media filtration
<br />ATTY/RESO.0074/CC RESO 847 WOODSIDE (CEQA) - EXHIBIT 1 - CEQA CONSISTENCY CHECKLIST
<br />REV: 10-23-24 VR
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