Laserfiche WebLink
G. Review and evaluate CCTV data of all storm sewer in the investigation area basins collected by <br /> the City. <br /> 3. Modeling and Alternatives Analysis <br /> A. Perform an analysis of the rainfall and flow monitoring data collected to determine appropriate <br /> dry weather and wet weather events to calibrate and validate the collection system model. <br /> B. Build a sanitary sewer collection system model in XP-SWMM,through the following: <br /> a. Create manhole(node) and sewer(link)files from existing GIS data. <br /> b. Perform a thorough analysis to check the accuracy of the data and identify any missing <br /> elements. <br /> c. Develop measures to address inaccurate and missing information and incorporate any <br /> additional or new information in the aforementioned files, where necessary. <br /> d. Build base models for the sanitary sewer systems. <br /> e. Incorporate hydraulic elements like pumps,weirs, orifices, sewers with special or irregular <br /> cross sections(if any). <br /> f. Develop dry weather flow loading and diurnal patterns. <br /> g. Develop hydrologic sewershed characteristics: basin boundaries, flow paths&lengths, <br /> impervious areas and soil types. <br /> h. Establish sewer system response to rainfall. <br /> i. Prepare and test the collection system models to ensure the models run without any errors. <br /> j. Import the database of flow and rainfall data collected and provided by ADS into the models. <br /> k. Compare sanitary sewer system model results to the real-time data provided by ADS. <br /> C. Calibrate and validate the collection system model using the rainfall and flow monitoring data <br /> collected by ADS using Wastewater Planning Users Group (WaPUG)2002 guidelines to achieve <br /> reasonably approximate response for total volume,peak flow and shape of the hydrographs. <br /> Calibration will be performed using three rainfall events, if possible. Validation will be <br /> performed using one independent rainfall event. <br /> D. Calculate a time of concentration to identify the duration of the design storms. Use the collection <br /> system model to identify existing system deficiencies for design flows(e.g., inadequate slopes, <br /> undersized pipes, etc.)and establish the existing level of SSO protection for the sanitary sewer <br /> system expressed in annual%probability of exceedance. <br /> E. Perform sewer system capacity evaluation using the following design storm events, as defined by <br /> National Oceanic and Atmospheric Administration(NOAA) for the Decatur area,to determine <br /> critical durations: <br /> a. 2 year <br /> b. 5 year <br /> c. 10 year <br /> d. 10 year—24 hour <br /> e. 25 year <br /> F. Identify and screen alternatives to reduce the collection system surcharging,provide additional <br /> conveyance capacity or storage to eliminate SSOs. <br /> G. Develop 5 feasible alternatives in sufficient detail to be adequately represented in the collection <br /> system model and run using the design storm events described in Item 3E. <br /> H. Utilize the collection system model to incorporate and evaluate alternatives to reduce <br /> surcharging,provide additional conveyance capacity, storage or green infrastructure to eliminate <br /> SSOs for the five design storm events and critical durations. <br /> I. Evaluate the collection system model results for each of the alternatives and critical duration <br /> storm events. <br /> Last Revised:04/29/2015 <br />