09-12-11 Regular Meeting of La Porte City Council

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kIotz , P 4)associates Mr. Julian Garza Jr., P.E. July 5, 2011 Page 4 of 7 13. Identify new developments or other information that will need to be included or need to be added into the hydrologic and hydraulic models that have been built that were not included in the previous models. 14. Work with surveyor to collect survey data such as channel sizes, flow lines, culvert sizes and flow lines and possibly some slab elevations. 15. Engage the geotechnical firm to perform the soils investigation. 16. Engage the environmental firm to prepare the environmental investigation. 17. Identify flooding and drainage problem areas from the initial data collection. Task #4 -- Review data collected 1. Perform broad based review of the collected data. 2. Determine options and scenarios to develop a base strategy for the potential solutions in the Battleground Estates area after reviewing the available data that has been collected to date. We will not have the results of the surveying, soils investigation or environmental investigation at this time. 3. Present summary of options and scenarios to City staff for confirmation on base strategy. Task 45 -T Evaluate models or other data: 1. Evaluate the modeling effort using the available hydrologic and hydraulic models. 2. Determine areas that need updating using available LIDAR or other data. 3. Determine areas where additional hydrologic or hydraulic modeling is needed based on a review of thc•available models, comparison of any planned development changes and therefore a determination that additional modeling is needed. 4. Coordinate with City on data that is available that may help in the modeling. Task #6 - Hydrologic and )E>i draulie ModeliM 1. Incorporate surveying data and or LIDAR data into the H &H models and incorporate additional improvements identified during the data collection phase into the models, 2. Include other specific information from staff or others. 3. Convert useful data from the previous plan into HEC -HMS models. Perform hydrologic analysis for establishing design flows for the watershed for the 5, 10, 50 and 100 year event storm events. HEC -HMS hydrologic models will be used to perform the sizing for watershed. The rational method or site runoff curves may be used for site specific analysis, where appropriate. The analysis is to determine the design flow rates under existing conditions and future developed conditions. 4. Update the flows for the watersheds using the available hydrologic data and other input data from tasks described above. 5. Convert useful data from the previous plan into HEC -RAS models. Perform hydraulic analysis of Battleground Estates roadside ditches and roadside ditch driveway culverts using a back. -water spreadsheet program and open channel drainage using the HEC -RAS computer program or a normal depth spreadsheet. The analysis is to evaluate the