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7.3.B. - Page 69 <br /> Summary of Impacts <br /> Potentially Less than Significant Less than <br /> Significant With Mitigation Significant No <br /> Impact Incorporated Impact Impact <br /> groundwater recharge such that there would be a net deficit in aquifer volume <br /> or a lowering of the local groundwater table level (e.g., the production rate of <br /> pre- existing nearby wells would drop to a level which would not support <br /> existing land uses or planned uses for which permits have been granted)? <br /> c) Substantially alter the existing drainage pattern of the site or area, including X <br /> through the alteration of the course of a stream or river, in a manner that would <br /> result in substantial erosion or siltation on- or off -site? <br /> d) Substantially alter the existing drainage pattern of the site or area, including X <br /> through the alteration of the course of a stream or river, or substantially <br /> increase the rate or amount of surface runoff in a manner which would result in <br /> flooding on- or off -site? <br /> e) Create or contribute runoff water which would exceed the capacity of existing X <br /> or planned stormwater drainage systems or provide substantial additional <br /> sources of polluted runoff? <br /> f) Otherwise substantially degrade water quality? X <br /> g) Place housing within a 100 -year flood hazard area as mapped on a federal X <br /> Flood Hazard Boundary or Flood Insurance Rate Map or other flood hazard <br /> delineation map? <br /> h) Place within a 100 -year flood hazard area structures that would impede or X <br /> redirect flood flows? <br /> i) Expose people or structures to a significant risk of loss, injury or death X <br /> involving flooding, including flooding as a result of the failure of a levee or <br /> dam? <br /> j) Inundation by seiche, tsunami, or mudflow? X <br /> Documentation: <br /> a. & e. The proposed project site is located within a Downtown urban setting, which is served by an existing storm drain <br /> system that outfalls into San Francisco Bay. Implementation of the proposed project would utilize the existing storm <br /> water conveyance facilities and would not contain uses that involve the discharge of cooled/heated water or <br /> pollutant -laden runoff. However, given the local urbanized area, the existing storm water flows contain urban runoff <br /> with contaminants such as oil, grease, particulates, metals, and solvents. Because the proposed project is subject to <br /> the requirements of an NPDES permit for municipal storm water runoff and other requirements of the City, County, <br /> and Regional Water Quality Control Board, the conditions of which limit the volume of contaminants allowed to <br /> enter the storm drain system, the proposed project would not violate any water quality standards or waste discharge <br /> requirements. Furthermore, the DTPP program EIR (pp. 10 -23 through 10 -25) concluded that DTPP facilitated <br /> development would not result in any significant water quality or storm water drainage impacts. The proposed <br /> project is in compliance with all applicable DTPP regulations, and as a result, no potentially significant water <br /> quality or storm water drainage impacts are anticipated with implementation of this project. <br /> A Preliminary Utility Study Summary report (BKF Engineers, May 19, 2014) has been prepared for the proposed <br /> project and is paraphrased here. Storm water runoff collected on the project site currently drains, and would <br /> continue to drain, to the City storm water system in Franklin and Wilson Streets. Due to an increase in impervious <br /> area under the proposed project (e g., approximately 25 percent of the site is currently a vacant, dirt lot), some <br /> storm water detention would be required; this detention would be provided in an underground structure located <br /> near the emergency vehicle access (EVA) adjacent to the Caltrain right -of -way. <br /> The City's Drainage Guidelines for Commercial Development require post - development storm water discharge to <br /> be equal to or less than pre- development discharge. Also, the City mandates that proposed site conditions maintain <br /> the same runoff for the 30 year storm event as compared to the existing 10 year event. Based on City of Redwood <br /> City Engineering Design Standard Attachment 0, the project would be required to detain 508 cubic feet (cu. ft.); the <br /> proposed detention facility would accommodate 550 cu. ft. All storm water data and components provided by the <br /> 20 <br />