Hydraulic Analysis. To determine the impacts associated with the project, floodplain hydraulic geometric models will be prepared for the portion of the creek system where the bridge will be located. The analysis will extend approximately a minimum of 1,000 feet upstream and downstream of the proposed bridge location in order to adequately assess project impacts. Available previously prepared floodplain hydraulic and floodway analysis performed by other investigators or agencies will be reviewed to ensure consistency with results and the hydraulic model variables. The floodplain evaluation will include the analysis of two different conditions, (1) baseline condition or an effective floodplain model reflecting the existing condition of the natural floodplain prior to the proposed bridge construction, and (2) developed condition or modified floodplain analysis, which includes the modifications of the floodplain for the proposed bridge crossing and potential encroachment within the floodplain. The hydraulic analysis will establish the water surface profiles and hydraulic parameters, which identify the characteristics of the floodplain. The floodplain will be evaluated utilizing the one dimensional water surface profile program developed by the Army Corps of Engineers, HEC-RAS. The hydrologic data for the 100-year flowrates which will be incorporated into floodplain model will be based upon previous hydrologic information and no additional regional hydrology will be performed as part of this study unless through separate addendum. Channel geometric data will be obtained from digital topographic mapping provided by OCPW for this project.
Hydraulic Analysis. Developer shall design riprap at abutments in accordance with the procedures outlined in HEC-23. For bridge abutments in urban areas, Developer shall install protection in accordance with the Project’s aesthetic plan.
Hydraulic Analysis a. All hydraulic design shall be design for a 50-year storm frequency design in accordance with the TxDOT’s Hydraulic Manual and U.S. Army Corps of Engineers as applicable, except where variances are permitted in writing by the Owner.
b. The Engineer shall review and comment on the hydraulic analysis for each existing and proposed structure location utilizing the HEC-RAS computer program; utilizing Xxxxxxx'x Equation to compute water surface profiles with the inputs of cross-section data, roughness coefficients, and flow rates. Specific steps for the hydraulic analysis are outlined in tasks (b) through (g) below.
c. The Engineer shall create the terrain Triangulated Irregular Network (TIN), if not provided by the Owner. This will be developed from a combination of field survey, aerial photogrammetry, and topographic mapping data in the development of a point table. With this point table, an event theme will be created in ArcView, which will create the terrain TIN with 3-D Analyst.
d. The Engineer shall create 2-dimensional lines representing the channel centerline, high bank locations, flow path lines, and cross-section locations by locating the various and required poly lines over the terrain TIN develop the watershed layout over the base map
e. The Engineer shall create the HEC-RAS GIS import file (ASCII text file); this will involve the correlation of the alignment of the cross-sections with the terrain TIN by extracting the elevations from the -"terrain-TIN atidtreating a3--dimensional cross-section theme.
f. For verification of measured elevations, the Engineer shall edit the HEC-RAS GIS import file by selectively replacing the points taken from the terrain TIN at the channel with actual channel points obtained by the field survey.
g. The Engineer will review and comment on the accuracy of the HEC-RAS modeling of the existing and proposed structures within the Project facilities authorized in work authorizations as outlined in Article 7 of the Agreement, and compare the hydraulic results to the effective FIS, existing and proposed 100-year flood levels.
h. After the HEC-RAS model is satisfactory and the output deemed acceptable, the Engineer shall apply the GIS export function to create the HEC-RAS export file in preparation for the flood plain mapping.
Hydraulic Analysis. For Little Eagle Creek Avenue over the Bear Creek tributary to Little Eagle Creek, establish pre- project conditions per IDNR guidelines for CIF permit. • Request and participate in an early coordination meeting with IDNR-Division of Water to discuss specific CIF permit requirements and conditions for this project. • Develop post-project model of proposed conditions to evaluate the impacts of construction on water surface elevations, consistent with IDNR guidelines. • Incorporate survey data into hydraulic models. • Develop hydraulic models for proposed pipe crossing and culvert replacements. • Consider one alternative for the three culvert crossing replacements based on the recommendations from the structure size and type report. The selected alternative will be evaluated for hydraulic impacts and CIF permit requirements, where applicable. • Prepare draft hydraulic reports for review by LPA. The reports will document the hydraulic analyses and findings. • Finalize post-project hydraulic model of selected alternativesand prepare final report. • Prepare CIF permit application for the selected alternative for the Bear Creek crossing. • Identify and Prepare Public Notice. Identify adjacent property owners. • Submit CIF Permit Application and supporting documentation to IDNR. • After CIF submittal, send out notifications to adjacent property owners. • Prepare calculations and figures to document required grading of compensatory floodplain storage. • Any effort relative to flood easements, if necessitated by this project for the IDNR CIF permit. • Survey and/or updates and/or corrections to existing unpublished hydraulic models at off-site locations if requested by IDNR for the CIF permit. • Stream restoration or mitigation plans related to conditions of required permits. • Permanent stormwater quality BMPs or stormwater detention or related local permits or approvals. [Remainder of Page Intentionally Left Blank]
Hydraulic Analysis. 21 Developer shall evaluate water surface elevations in the main channel for existing and proposed 22 conditions for sizing of bridge waterway openings. The hydraulic analysis and design must 23 account for the presence of any additional existing control structures that may affect the 24 hydraulic performance and design of the structure. Developer shall identify and mitigate all 25 negative hydraulic impacts caused by the Project. 26 Developer shall ensure that the hydraulic analysis of bridge crossings at Effective FEMA Special 27 Flood Hazard Zone adhere to those mandates as outlined by the applicable Governmental 28 Entity and federal mandates as contained within FEMA Code of Federal Regulations (CFR) for 29 the National Flood Insurance Program: 44 CFR Parts 59, 60, 65, and 70. 30 Developer shall use HEC-RAS Water Surface Profile Program (the most current version as of 31 the Setting Date) to perform hydraulic analyses at bridge crossings, including culvert structures 32 that meet bridge definitions, for both existing and proposed conditions.
Hydraulic Analysis. Not in contract.
Hydraulic Analysis. The model shall be used to evaluate the hydraulic capacity of the collection system. The evaluation shall include determination of the following: Capacity deficiencies. Critical pipeline segments. Identification of new pipe segments that could improve overall system flow dynamics. Identification of new pipe segments and projects that could reduce the number of lift stations. Consultant shall provide analysis and results for three flow projections: low, medium, and high relative to population and development projects described in City and County planning documents. Medium population projection shall be based on projections used in the City of Chico General Plan 2030. Consultant shall incorporate results from flow monitoring to calibrate and validate flow model results.
Hydraulic Analysis i. The Consultant shall perform a hydraulic analysis to verify the existing capacity of the East Primary Clarifiers.
ii. If the existing capacity of the clarifiers is not adequate to meet Effluent Peak Hour Wet Weather Flow (EPHWWF), the Consultant shall recommend and incorporate improvements within the VH model to meet EPHWWF (adding additional inlets, raising weirs or walls, performing flow distribution modifications, increasing conduit sizes, etc.). in agreement with the City.
iii. The Consultant shall subsequently perform a hydraulic analysis to evaluate whether the East Primary Clarifiers can accommodate the EPHWWF after the recommended improvements are incorporated.
Hydraulic Analysis. The Consultant will perform a hydraulic analysis in accordance with the principles outlined in the Section 3.4
Hydraulic Analysis. 6.2.1 Develop a Revised Existing HEC-RAS model to calculate water surface elevations, velocities, and valley storage. The Revised Existing model will be created by copying the Town’s effective hydraulic model from the completed Fishtrap Road Reconstruction project and updating with current survey data and conditions in the project area. This scope assumes that the effective hydraulic model is a 1D steady flow HEC-RAS hydraulic model with existing 100-year and fully developed 100-year flows. Unsteady flow analysis, 2D analysis, or hydrologic analysis could be performed as Additional Services.
6.2.2 Delineate the Revised Existing floodplain for the existing 100-year and fully developed 100-year storm events.
