Res 2010-156 (Tabled) - Laserfiche WebLink

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year frequency event, and include structure size, flow line elevations and approximate structure location in the plan sheets. Evaluate temporary drainage ditches between temporary drainage structures and outfall locations and designate a typical ditch section in the plans along with plan notes for the construction contractor to maintain positive drainage for these temporary ditches. 1.7.6 Definitions 1) Hydrologic Impacts: Increases in peak flow rates for required design storm events outside of TxDOT's or the City's ROW. 2) Hydraulic Impacts: Increases in water surface elevations for required design storm events outside of TxDOT's or the City's ROW, and /or changes in water velocity. 1.7.7 Hvdrolo2v 1) Analyze and document existing condition peak flows for cross - drainage structures and drainage outfalls leaving TxDOT or City ROW. 2) Analyze and document proposed condition peak flows for cross - drainage structures and drainage outfalls leaving TxDOT or City ROW. In addition, provide guidance on the design of alternatives that will minimize or potentially eliminate hydrologic impacts. 3) Develop discharges for cross - drainage structures for required storm events, i.e., the 25 -year storm events. 4) Develop discharges for internal drainage structures, including storm drain systems and culverts, for the design storm and 100 -year check storm. 5) Determine the design storm for internal drainage structures by considering guidance in the HDM, in combination with an assessment of existing drainage features on the roadway segments adjacent to this Project. Assess existing drainage features by focusing mainly on storm drain capacity, past performance, and any planned future upgrades to the roadway segments. The Engineer will receive input from the TxDOT project manager (PM), and the Austin District Hydraulics Engineer (DHE) regarding this assessment. TxDOT will make the final storm design determination. 1.7.8 Hvdraulics. 1) Analyze and document existing conditions and hydraulic rating data for cross - drainage structures and drainage outfalls leaving TxDOT or City ROW. 2) Analyze, design, and document proposed conditions for cross - drainage structures and drainage outfalls leaving City or TxDOT ROW. Determine proposed conditions hydraulic impacts by comparing proposed and existing conditions hydraulic rating data outside of TxDOT or City ROW. 3) Analyze cross - drainage structures for standard storm events, i.e., the 2, 5, 10, 25, 50, and 100 -year storm events. 4) Analyze drainage structures using appropriate and standard procedures and/or software. HDR — Loop 82 Project Agreement 20