Washington Street West watershed - City of Champaign

Draft ReportWest Washington Street Watershed Master PlanGOAL C:Develop alternatives to improveconditions in problem areasDescription:The drainage area served by the West Washington Street storm sewer is entirely developed, witha few open areas near the industrial facilities and at parks. Incorporating flood control solutionsinto the existing watershed will require creative options and this Watershed Master Plan aims todevelop multiple options in an attempt to improve the drainage analysis and provide betterrecommendations. The existing conditions XP-SWMM model was modified to estimate howeach option would perform under expected hydrological conditions. Each multi-phase alternativescenario would be subjected to identical hydrological conditions and adjusted so that surfaceflooding for the 10-year, 2-hour storm would not occur at the intersection of West Washingtonand North Russell, as well as at the other identified areas throughout the watershed. Waterquality benefits of each alternative were studied on a conceptual level and benefits of eachalternative were included in the final analysis.Objectives:1. Modify the existing conditions XP-SWMM model to incorporate the various alternatives intoseparate model scenarios.2. Test the multi-phase improvement scenarios against the 10-year, 2-hour storm to demonstrateno ponding at the intersection of West Washington and North Russell and no surfacesurcharge along the main trunk sewers. Analyze each scenario against the 50-year, 2-hourstorm event to verify the extent of flooding and flood routing for large storm events.3. Address the economic and construction feasibility of each alternative in the final analysis,with consideration towards phasing and implementation strategy.September 20092-9Clark Dietz, Inc.