2006-08-02_PERMIT FILE - C1980007 (8)

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SYLVESTER GULCH ACCESS ROAD HydroloQic /Hydraulic Analysis for Roadway Draina~ Originally Submitted March 8, 2005 Revised June 8, 2005 1.0 PROJECT DESCRIPTION This hydrologic /hydraulic analysis fot the roadway drainage system was utilized for the Sylvester Gulch Access Road design between the Stations 82+51.53 and 150+76.22. The purpose of this analysis is to develop design data for storm water runoff released from the watershed around the road. The drainage system includes modified natural channels, road side ditches, trunk lines, cross culverts, cross drains, check dams, and associated appurtenance. Watershed hydrologic conditions were modeled using ahydrologic /hydraulic computer program, SEDCAD 4 for Windows, which was developed by University of Kentucky, released in 2004 (Warner, 2004). Hydraulic characteristics of trunk lines were modeled using computer program HYDRA that is included in the Federal Highway Administration (FHWA) Integrated Drainage Design Software HYDRAIN for Windows, Version L0, released in 2001 (FHWA, • 2001). Open channel hydraulics was calculated using Haestad Methods computer program FlowMaster, Pipe and Ditch Sizing Softwaze, Version 5.15 (Haestad Methods, 1996). Hydrologic / hydraulic model input data were established through analyzing of the U.S. Geological Survey (USGS) topographic quadrangle maps (USGS, 1964-1 and 1964-2), review of published reports and design plans, survey data, and observations from site inspections. 2.0 HYDROLOGY 2.1 Methodology The evaluated watershed encompasses a contributing area of 1,033 acres, and was delineated and divided into 20 subdrainage basins (sub-watersheds) based on the USGS topographic maps, survey data, and prelimigary design concepts as shown on the attached Plate I. Section 2.0 establishes the peak runoffs and sediment load generated from sub-basins, determines the trunk line sizes, and locates and sizes required cross culverts and cross drains. Resulting peak dischazges obtained in this section will be used in Section 3.0 to model the hydraulic grade line in the trunk lines, to calculate the velocities in the channels and to design the channel protection based on the findings. The contributing area and the roadway drainage system were modeled simultaneously using the watershed modeling sofrwaze SEDCAD 4 for Windows. SEDCAD 4 is a comprehensive program that includes hydrology, hydraulics, and design and evaluation of the effectiveness of both individual and an integrated system of erosion prevention and sediment control measures. The . program uses classic, well-established methodologies for hydrologic and hydraulic analysis. The SCS Unit Hydrograph method has been slightly modified to establish more accurate prediction of disturbed lands and forested areas. Hydraulic routing techniques and al] designs were performed