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Mitigation Monitoring and Reporting Program H. Infrastructure Systems: Drainage <br />Page 10 <br />Mitigation Specifications Flood Control Policy 2: On-site Flood Protection. Retain on-site <br />(cont'd): any increase in peak storm water runoff resulting from development <br />under the 100-year storm event. <br />Guideline 2.1: In developing Phase I, incorporate storm <br />water detention basins into the Phase II portion of the site, capable <br />of retaining increases in post-development peak runoff from the site <br />resulting from a FEMA 100-year storm event. <br />PUD approval conditions require: <br />• that all storm drain improvements must be based on storm water run- <br />off modeling demonstrating sufficient capacity, and storm drain deten- <br />tion basin must detain runoff anticipated under 100-year storm events <br />(Condition 57) <br />• along-term maintenance plan for [he detention ponds, which will <br />ensure that the storm drainage improvements are managed and oper- <br />ated as required (Condition 57(e)(ii)). <br />Specifications: <br />(I) Provide one or more detention/retention basins with an aggregate <br />capacity to retain runoff from [he 100-yeaz storm event. <br />(2) Construction the deten[ion/reten[ion basins during the site devel- <br />opment (grading) process. <br />(3) Prepare a maintenance plan for the detantion/reteution basins to <br />assure that [hey retain [he design capacity sufficient to retain runoff <br />from the 100-year storm event over the life of [he project. <br />(4) Maintain detention/retention basins consistent with the maintenance <br />the plan. <br />Agency/Individual <br />Responsible for <br />Mmitoring: City of Pleasanton, Planning Deparunen[ and Public Works Department <br />Action by Monitor: (1) Assure that all grading plans include appropriate onsi[e detention/ <br />retention facilities. <br />(2) Assure that detentiotJrctention facilities are provided consistent <br />with plans. <br />(3) Review and approve maintenance plan fur detention/retention <br />facilities. <br />(4) Assure that detention/retention facilities are maintained so [hat that <br />they continue to provide the required capacity (sufficient to retain <br />runoff from the 100-year storm event). <br />