Hydrologic Studies. The Engineer shall provide the following services:
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.
2. Calculate discharges using appropriate hydrologic methods and as approved by the State.
3. Consider the pre-construction and post-construction conditions in the hydrologic study, as required in the individual Work Authorization.
4. 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.
5. 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).
6. 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.
Hydrologic Studies. The Engineer shall provide the following services:
a. 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.
b. Calculate discharges using appropriate hydrologic methods, as included in this document or as approved by the STATE.
c. Consider the pre-construction and post-construction conditions in the hydrologic study, as required in the individual Work Authorization. The additional lanes may be accounted for by increasing percent development or by a higher curve number, as deemed appropriate for the site.
d. 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, DocuSign Envelope ID: 81458207-9CCE-4B63-AE14-3C13B2D84757 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.
e. The plan set must include, at a minimum, the “design” frequency to be specified in the Work Authorization and the 1% AEP storm frequency. The report must include the full range of frequencies (50%, 20% 10%, 4%, 2%, 1%, and 0.2% AEP). Perform scour evaluations for both the 100yr and 500yr frequencies.
f. 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.
Hydrologic Studies. The Engineer shall provide the following services:
161.2.1.1. 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.
Hydrologic Studies. The Engineer shall provide the following services:
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.
2. Calculate discharges using appropriate hydrologic methods and as approved by the State.
3. Consider the pre-construction and post-construction conditions in the hydrologic study, as required in the individual Work Authorization.
4. 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. DocuSign Envelope ID: 981599F8-5D6E-41E6-ADFA-1DA0DC55F35E
5. 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).
6. 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.
Hydrologic Studies. The Engineer shall provide the following services:
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.
2. Calculate discharges using appropriate hydrologic methods and as approved by the State.
3. Consider the pre-construction and post-construction conditions in the hydrologic study, as required in the individual Work Authorization.
4. 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. DocuSign Envelope ID: 8F4C5F80-CEA4-4B7A-AA13-EF50310E0F8C
5. 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).
6. 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.
Hydrologic Studies. The Consultant shall provide the following services:
a. 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.
b. Calculate discharges using appropriate hydrologic methods, as included in this document or as approved by the State.
c. Consider the pre-construction and post-construction conditions in the hydrologic study. The additional lanes must be accounted for by increasing percent development or by a higher curve number, as deemed appropriate for the site.
d. Obtain the drainage area boundaries and hydrologic parameters such as impervious covered areas, and overland flow paths and slopes from appropriate sources such as, topographic maps, GIS modeling, construction plans, and existing hydrologic studies. The Consultant shall not use existing hydrologic studies without assessing of their validity. Obtain additional local rainfall from official sites such as airports.
e. 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.
Hydrologic Studies. The Engineer shall provide the following services:
Hydrologic Studies. The Engineer shall provide the following services:
1. Review and verify hydrology results from the schematic portion of this project.
2. Validate and update as needed the discharges developed in the schematic portion of this project
3. Verify the pre-construction and post-construction conditions developed in the schematic portion of this project in the hydrologic study.
4. 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 (specifically the schematic drainage study). 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.
5. Include, at a minimum, the “design” frequency 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).
6. Compare and verify calculated discharges developed in the schematic portion of the project 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. For each identified outfall, the Engineer shall quantify the change in peak flow rates between the existing and proposed conditions created by the project. The Engineer shall then determine if the overall increase in peak flow from the project compared to the peak flow in the receiving channel or storm drain system will create an adverse impact to the adjacent properties or existing storm drain systems. If the Engineer determines that the project will create adverse impacts to adjacent properties, the Engineer shall identify potential on-site locations for detention storage and assess potential detention storage availability. The Engineer may recommend detention structures in the form of ponds and ditches where the ROW area allows or within oversized storm drain conduits in locations with limited ROW area. Utilizing hydrograph routing software such as Hydrologic Engineering Center – Hydrologic Modeling System (HEC-HMS) or Storm Water Management Model (SWMM), the Engineer shall calculate required storage volumes based on hydrograph calculations and peak flows in order to limit 100 year discharge from each DocuSign Envelope ID: 27...
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:
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.
2. Calculate discharges using appropriate hydrologic methods and as approved by the State.
3. Consider the pre-construction and post-construction conditions in the hydrologic study, as required in the individual Work Authorization.
4. 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.
5. 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).
6. 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.
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.
