PC 2000-46 - Laserfiche WebLink

Designs for ~:C~l..improvements shall include restoration and enhance~nt Of riparian vegetation along the bottom and banks of the channel following construction. Flood Control Policy 2: On-Site Detention. Retain on- site any increase in peak storm water runoff resulting from development under the 100-year storm event. GUIDELINES: 2.1 In developing Phase I, incorporate storm water detention basins into the Phase Il portion of the site, capable of retaining increases in post- development peak runoff from the site resulting from a lO0-year storm event. 2.2 Coordinate with Zone 7 on storm water release patterns to meet regional flood control objectives. Flood Control Policy 3: On-Site Flood Protection. Protect on-site development against flood hazards by allowing habitable buildings only in locations and at elevations outside the 100-year flood plain. GUIDELINES: 3.1 If regional flood control improvements are not assured for the Arroyo de la Laguna prior to implementation of the Phase I grading plan for the Western Area, allow protection of on-site development in the Western Area by either raising residential pad elevations and/or constructing a berm/levee along the western edge of Parcels 1 and 2. Such measures may provide protection against flood flows of at least the then-best estimate of future 100-year flood flows, without placing existing development on the west side of the arroyo adjacent to the Planning Area at increased risk of flooding. [Current FEMA flood maps show that the 100 year flood event of 17,000 cfs through the Planning Area would be contained within existing banks of the channel of the Arroyo de la Laguna. Estimates for future flood flows range from 17,000 cfs to 27,000 cfs. Zone 7 is currently re-evaluating their flood flow estimates; however, results of their study are not currently available.] 6-7