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City of Santa Ana Environmental Checklist d. Substantially alter the existing drainage pattern of the site or area, Including through the alteration of the course of a stream or river, or substantially Increase the rate or amount of surface runoff in a manner that would result in flooding on site or off site? Less - than - Significant Impact with Mitigation Incorporated. Refer to IX.c. Development of the proposed project would not impact a river course or flow patterns. Existing Bows from the project site enter the street and then a regional stormdrain, as described in IX.c. The overall drainage pattern of the site would not be substantially altered. The planned operational stormwater drainage for a majority of the project site will direct surface flow to drain into grassy swales that are designed to accommodate the site and will retain stormwater that will be filtered into the ground. Stormwater not captured by the proposed landscaping or grassy swales will either be intercepted by drain inlets in the parking garage and pumped to the sanitary sewer, or will flow to the existing curb and gutter on Sullivan Sheet. The project does not include changes to the existing offsite drainage patterns. Offsite stormwater flows from the proposed project would be conveyed in the same manner as existing conditions, and the project would not substantially alter the existing drainage pattern of the site. As a result, stormwater flows from the project site would not result in flooding on or off site. As discussed in IX.a, Mitigation Measure HYD -1 would ensure that General Construction Permit and a SWPPP containing BMPs and a WQMP would be obtained, which would address flooding issues for- construction and post - construction phases. As a result, the proposed project would not alter the existing drainage pattern or increase runoff in a manner that would result in flooding. Therefore, impacts are less than significant with incorporation of Mitigation Measure HYD -1. e. Create of, contribute runoff water that would exceed the capacity of existing or planned stormwater drainage systems or provide substantial additional sources of polluted runoff? Less - than - Significant Impact. Refer to IX.a and IX.c. As described above, the proposed project would not alter the existing offsite drainage pattern or substantially change the amount of stormwater that would sheet flow offsite. The project includes development of vegetative swales on the northern and southern site boundaries that will catch and retain stormwater from a large portion of the project's impervious surfaces, as provided in the drainage study (Appendix C). With implementation of the proposed grassy swales and landscaping, redevelopment of the site would not generate an increase in runoff water that would exceed the capacity of the existing or planned stormwater drainage system. As described in Section XVII, "Utilities," the site is located within an urban and fully developed area with curb and gutter drainage that directs flows to the existing regional stormwater drain in Mcpadden Avenue that has historically been serving the project site and vicinity. The project will not include changes to the existing offsite drainage system or pattern. Therefore, the project would result in less- than - significant impacts related to the capacity of existing and planned stormwater drainage systems. f Otherwise substantially degrade water quality? Less - than- Signifcant Impact with Mitigation Incorporated. As described in IX.a through IX.e, the proposed project would result in less- than - significant short -term construction or long -term operational impacts on water quality. Construction impacts would be reduced through the implementation of BMPs identified in Mitigation Measure HYD- I. Operational impacts would be reduced by implementation of the project WQMP, as regulated by the Orange County NPDES Permit The Bat Nha Buddhist Meditation Center 3 -56 June 2013 Initial Study /Mitigated Negative Declaration ICE 00215.12 31 C -109