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South Coast Technology Center Project
<br />CEQA Exemption 15183
<br />comply with the latest CGP (Order No. 2022-057-DWQ) and RR HYD-1, which requires filing a
<br />Notice of Intent, a Risk Assessment, a Site Map, a Storm Water Pollution Prevention Plan (the
<br />Project Site is larger than one acre) and associated best management practices, an annual fee,
<br />and a signed certification statement.
<br />As the Project would introduce a new use to the Project Site (i.e., industrial/warehousing), the
<br />proposed Project would be required to comply with the requirements of the General Industrial
<br />Permit and RR HYD-2. A preliminary WQMP has been prepared for the proposed Project to
<br />comply with the requirements of the County's NPDES Stormwater Program (RR HYD-4) and be
<br />consistent with the Orange County Drainage Area Management Plan; refer to Attachment H,
<br />Preliminary Water Quality Management Plan. The WQMP describes site design and drainage,
<br />and structural and non-structural source control BMPs for the proposed Project to ensure water
<br />quality standards or waste discharge requirements are not violated, and to prevent substantial
<br />erosion or siltation on- or offsite. The proposed Project would also be required to comply with the
<br />SAMC regarding prohibitions on illicit connections and discharges, urban runoff control measures,
<br />and permit requirements. As a result, consistent with the GPU PEIR, water quality impacts
<br />associated with construction and operational activities would be less than significant.
<br />Regarding water demand, the proposed Project is anticipated to require less water than the
<br />existing office building use due to a reduction in fixtures; refer to Section 4.19, Utilities and Service
<br />Systems, for additional details. Thus, the proposed Project would be consistent with the General
<br />Plan Update. Regarding pervious surfaces and runoff, according to the Attachment I, Preliminary
<br />Drainage and Hydrological Study (Drainage Study), prepared by Incledon Consulting Group,
<br />dated June 2024, the proposed Project would increase imperviousness but due to modifications
<br />in stormwater flow paths within the Project Site, peak runoff produced from the site is expected to
<br />decrease or remain the same as existing conditions; refer to Preliminary Drainage and
<br />Hydrological Study. Additionally, the Drainage Study determined that the proposed Project has
<br />been designed to effectively capture and convey the Project's storm water to the existing/public
<br />systems during a 10-year storm, utilizing a new on -site storm drain system that would collect
<br />surface water from the on -site BMP catch basins. The system would continue the flow patterns of
<br />the existing conditions by utilizing the street's infrastructure and an on -site storm drain system.
<br />Therefore, consistent with the GPU PEIR, impacts would be less than significant.
<br />According to Figure 5.9-4, City of Santa Ana Flood Zones, of the GPU PEIR, the Project Site is
<br />not within a 100-year flood hazard area as designated by the Federal Emergency Management
<br />Agency (FEMA). According to Figure 5.9-5, Dam Inundation Areas, of the GPU PEIR, the Project
<br />Site is within both the Santiago Creek Dam and Prado Dam inundation areas. However, the
<br />Santiago Creek Dam has been assessed by the California Division of Safety of Dams (DSOD) to
<br />have no existing or potential dam safety deficiencies and the U.S. Army Corps of Engineers' Dam
<br />Safety Program is actively implementing risk -reduction measures to remediate the Prado Dam,
<br />including routine inspections and ongoing monitoring, spillway modifications to improve
<br />downstream flow, and public outreach, to ensure potential inundation hazards are minimized or
<br />eliminated.27 The GPU PEIR determined that, while seiche theoretically could occur with these
<br />reservoirs, the flooding impacts would be less than the inundation zones. The GPU PEIR also
<br />determined that the City is too far inland to be at risk of a tsunamis. As such, implementation of
<br />27 U.S. Army Corps of Engineers, Corps reclassifies Prado Damn, implements risk -reduction measures,
<br />https://www.spl.usace.armV.mil/Media/News-Releases/Article/1849301 /corps-reclassifies-prado-dam-implements-
<br />risk-reduction-measures/, May 15, 2019.
<br />July 2024 Page 70
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