PC-99-80 - Laserfiche WebLink

a. The Master PUD storm drainage exhibit 4 shows adequate facilities to ensure no net runoff from the Project. Engineering studies indicate that the Project must reduce potential runoffby approximately 82 cfs during the peak storm event. The detention/retention facilities will have capacity for 24 acre feet, eliminating any net increase in runoff. b. The September 1998 Specific Plan Project features and facilities have been designed to accommodate runoff, including (1) extensive permeable surfaces in the golf course, park and open space areas; (2) storm water retention facilities incorporated into the golf course; and (3) retention facilities capable of retaining project runoff in the 100-year storm event. c. The September 1998 Specific Plan the Public Facilities and Service Element, Storm Drainage Policy 2, Guidelines 2.1 and 2.3, call for retaining runoff under the 100-year storm event, and incorporating detention basins in the golf course, parks and open space capable of retaining runoff from the 100-year storm event. d. Master PUD Conditions 74a and 74e require that all storm drain improvements must be based on storm water runoff modeling demonstrating sufficient capacity, and storm drain detention basins must detain peak runoff anticipated under 100-year storm events. e. Master PUD Condition 74e requires a long-term maintenance plan for the detention ponds, which will ensure that the storm drainage improvements are managed and operated as required. 2. Imoact B3. Localized flooding may occur due to storms in excess of design capacities of side channels or culverts. Mitil!ation Measure: Measure B3. Design subdivision (channels, culverts, streets, open spaces, retention basins, and site grading) in a comprehensive manner such that no habitable buildings are subject to flooding in a 100-year storm event. Findinl!s: Changes or alterations have been required in, or incorporated into, the Project which avoid or substantially lessen the significant environmental effect identified in the Final EIR to a less than significant level. Facts in SUDDort ofFindin~: The impact will be avoided or reduced based on the following: a. This mitigation is incorporated in the September 1998 Specific Plan, Public Facilities and Service Element, Stann Drainage Policy 2, Guideline 2.4 which requires all subdivision improvements, such as storm drain lines, streets, curbs and gutters, channels and culverts and open spaces be designed in a comprehensive manner such that no SF:FMP\AGR\WEX\61131664.2 062499 A-5 WEX-66013