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realistically than a steady state model would be able to accomplish. Dynamic models yield true representations of the water levels at any point in space and time by allowing for the effects of storage. backwater, and the timing of the hydrographs in conduits and floodplains. The following three tasks were identified by the City of Roseville as the original scope of services for URS to complete for the Charlie Pond Storm water Modeling Project. Task #1 consisted of collecting data required to accurately model the Charlie Pond watershed. The physical characteristics of the existing storm sewer system were defined by the following sources of information: 1. Roseville storm sewer as-builts for watershed 2. Shoreview storm sewer as-builts for northeru drainage area 3. Roseville GIS (contours, roadways, storm pipes, building footprints) 4. Shoreview GIS (contours only) 5. Previous Roseville HydroCAD models 6. Previous Roseville drainage study reports and memos 7. Neighborhood historical data for rain events and depth of flooding 8. Inlet casting inventory for all streets. (Inlet castings tell us how much water can enter the storm sewer system during a rain event) Task #2 involved setting up the XPSWMM model for the existing conditions. Individual sub-tasks included: 1. Data entry of physical characteristics of the stormwater system including pipe, drainage areas, available storage, and outlet! inlet structures, etc. 2. Establishing and entering hydrologic data including time of coucentration, rainfall intensity, curve numbers, etc. 3. Reviewing developed model with previously completed models 4. Running model to verify continuity with historical data collected Task# 3 involved running the existing conditions XPSWMM model and analyzing results. Individual sub-tasks included: 1. Run the model for 2, la, and 100 year storm events 2. Analyze data and identify high water elevations and locations of flooding, if present 3. Summarize data in a memo EXISTING CONDITION DRAINAGE STUDY SUMMARY URS worked closely with the City of Roseville through multiple meetings and site visits to the neighborhood in order to collect the data summarized above for Task #1. Task #2 began with the establishment of the hydrologic data specific to the area. In order to run an XPSWMM model, hydrologic information is needed in addition to the physical data provided on as-builts and other historical documents. A list of the hydrologic information collected is summarized below: Hydrologic Data 1. This watershed was modeled using the SCS unit hydrograph method. 2. A type II, 24 hour distribution curve was applied to define the rain intensity in relation to time. 3. The rainfall intensity was defined by the MNDOT drainage manual in Appendix B(l), B(3), and B(6), with a value of 2 year storm = 2.7", 10 year storm = 4.2", and 100 year storm = 6.0". (By definition, a 100 year storm has a I % probability of occurring in any given year.) 4. Curve numbers (value used to classify the land use and soil type) for this model were chosen utilizing HydroCAD and verified with the MNDOT Drainage manual (table 3.11 SCS Curve Numbers for Urban Land Uses) under soil type B. (Type B soils have moderate infiltration rates when thoroughly wetted and typically consist of sandy clay to clayey sand type materials) 5. Time of concentration for storm runoff was calculated for each sub drainage area, with the minimum 20f6