Hydrologic Studies. The Engineer shall provide the following services:
Hydrologic Studies. The Engineer shall provide the following services: DocuSign Envelope ID: DB60124E-7585-4844-AF91-B8FDD08F857C
Hydrologic Studies. The Consultant shall provide the following services:
Hydrologic Studies. The Engineer shall use FEMA determined discharges form the Flood Impact Studies where available. For minor non-FEMA classified crossings the Engineer shall calculate discharges using Rational Method for drainage areas less than 200 acres. For areas greater than 200 acres, the Engineer shall be calculated in accordance with the State’s Hydraulic Design Manual (latest Edition).
Hydrologic Studies. The Engineer shall perform a preliminary hydrologic analysis to determine the discharges for the 2-, 10-, 25, 50, 100, and 500-year storm frequency events. Drainage areas delineated under 200 acres shall use the Modified Rational Area Method. Areas greater than 200 acres shall use the Soil Conservation Service (SCS) Curve Number Method as described in the TXDOT 2011 Hydraulic Design Manual.
Hydrologic Studies. The ENGINEER shall perform a preliminary hydrologic analysis to determine the discharges for the 2-, 10-, 25-, 50-, 100-, and 500-year storm frequency events. Drainage areas delineated under 200 acres shall use the Modified Rational Area Method. Areas greater than 200 acres shall use the Soil Conservation Service (SCS) Curve Number Method or statistical analysis of stream gage data depending on available data as described in the TXDOT 2016 Hydraulic Design Manual. The ENGINEER shall complete the following subtasks: Obtain data. The ENGINEER shall obtain existing Hydrology and Hydraulic models from drainage authorities with purview in the corridor. Other data sources shall include and are not limited to: − FEMA Flood Insurance Studies (FIS) and Flood Insurance Rate Maps (FIRMs) − Latest available terrain surface data and contour maps (from local County or TxDOT) − Land use maps − Soils maps − Historic Precipitation Data − USGS Stream gage data − Aerial imagery (latest available) − Culvert and drainage maintenance reports − Historic Flooding reports − As-built plans and data for impacted hydraulic structures DocuSign Envelope ID: 9E4E3B84-8519-409C-AEF8-0383FB0D2E89 − Design plans (calculations if available) of highway, culverts and ditches Review FIS. The ENGINEER shall review the FEMA Flood Insurance (FIS) and Maps (FIRMs) and compare to the proposed improvements. The ENGINEER shall evaluate the potential impact to the delineated floodplain area Determine Drainage Area Boundaries. The ENGINEER shall determine the existing conditions drainage area boundaries to be used for determining discharges for cross drainage structures, channels, and detention ponds. The delineations shall be based on the available terrain surface data, contour maps, as-built data, and aerial imagery. The ENGINEER shall conduct up to two site visits when needed to identify critical hydrologic and hydraulic areas not visible on maps. Ground survey (to be provided by the STATE) and the latest available terrain surface data and available contour maps along with current aerial imagery shall be used to identify any existing drainage features such as channels, cross drainage structures, roadways, or structures. Complete Hydrologic data/discharge calculation. Time of Concentration calculations will be performed as stated in the TxDOT Hydraulic Design Manual July 2016 edition. Calculated flows shall be compared to FEMA FIS flows and TxDOT’s Regression Analysis Equations. Hydraulic Model...
Hydrologic Studies. Contract No. 18-7SDP5010 DocuSign Envelope ID: DADDA27D-207C-44D8-A3A7-49A72052A5A9 PS No. 6837 If the revisions of the provided report are required, the Engineer shall provide the following data collection services for the frontage road bridges over lake Xxx Xxxxxxx as directed:
Hydrologic Studies. The Engineer shall provide the following services: The Engineer shall provide updates to the technical memorandum completed during the schematic phase, including minor changes to bridge and culvert crossings.
Hydrologic Studies. The Engineer shall provide the following services: Delineate drainage boundaries, develop hydrologic parameters and calculate discharges using appropriate hydrologic methods and as approved by the State. Compare calculated discharges to the effective FEMA flows. If calculated discharges are to be used in the model instead of the effective FEMA flows, full justification must be documented. Consider the pre‐construction and post‐construction conditions in the hydrologic study, as required in the individual Work Authorization. Include, at a minimum, the “design” frequency to be specified in the Work Authorization and the 1% Annual Exceedance Probability (AEP) storm frequency. The report must include the full range of frequencies (50%, 20% 10%, 4%, 2%, 1%, and 0.2% AEP). Incorporate in the hydrologic study a thorough evaluation of the methodology available, comparison of the results of two or more methods, and calibration of results against measured data, if available. Obtain the drainage area boundaries and hydrologic parameters such as impervious covered areas, and overland flow paths and slopes from appropriate sources including, but are not limited to, topographic maps, GIS modeling, construction plans, and existing hydrologic studies. The Engineer shall not use existing hydrologic studies without assessing of their validity. If necessary, obtain additional information such as local rainfall from official sites such as airports.
Hydrologic Studies. The Engineer shall provide the following services: DocuSign Envelope ID: E73D9091-6C82-469F-B42B-3F0B45BB646B Contract No. 36-6IDP5268 PS No. 5282 Supplemental Agreement No. 1 1. Incorporate in the hydrologic study a thorough evaluation of the methodology available, comparison of the results of two or more methods, and calibration of results against measured data, if available.
