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. 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 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.
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. 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. Alternative Development and Analysis • 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. Hydraulic Report Preparation • 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. IDNR CIF Permit Application • 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. Compensatory Floodplain Storage • Prepare calculations and figures to document required grading of compensatory floodplain storage. Items Specifically Not Included • 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. 13.a.2. Scour Analysis: • Hydrologic and Hydraulic documents for the Conceptual TS&L structure prepared by the Department are preliminary and for information purposes only. Prepare the final H&H documents. Prepare and submit for approval the appropriate waterway permit(s) using the final H&H documents and in accordance with the conditions of the permit. • Scour Analysis is preliminary and for information purposes only, Prepare Scour Analysis in conjunction with final H&H documents.
Hydraulic Analysis. Not in contract.
Hydraulic Analysis. Hydraulic parameters (water surface elevations and velocity) will be obtained from the Army Corps of Engineers HEC-RAS (Hydraulic Engineering Center River Analysis System) model based on: 1) The HEC model available from FEMA through Xxxxxxx Xxxxx Jr., 2) 8 to 10 channel cross sections by the consultant team to validate and extend the topography in the model upstream, 3) as-built data provided by Caltrans, 4) and a reconnaissance level field investigation by Xxxxx and Associates. Calibration: Calibration data will be researched to determine if any highwater elevations were recorded for the flood of record. If calibration data can be found, it will be used to calibrate the HEC-RAS model by running the HEC-RAS model and adjusting the model parameters until the discharge associated with the highwater marks can be replicated with the model. Variable discharges will be input into HEC-RAS to determine the discharge that provides a water surface elevation of matching the calibration data. Calibration data was used to validate the hydraulic model for the bridge. The Hydraulic Model – HEC-RAS Analysis: The river reach will be described. Xxxxxxx’x “n” values for the channel and overbank will be estimated from field investigation and engineering judgment. Two steps will be used to develop the HEC-RAS Models. Obtain the existing HEC model Obtain existing model from FEMA through Xxxxxxx Xxxxx Jr. Xxxxx and Associates will complete a survey request outlining the location and extent of cross section data necessary to check the survey data from the available HEC- RAS hydraulic model and extend the model upstream of the existing bridge. It is expected that eight to ten cross sections would be required. Proposed Bridge Model The HEC-RAS model will be re-run for various design discharges for the proposed replacement bridge. The model will also incorporate any encroachment from bridge approach fills. The hydraulic variables (water surface elevation, velocity etc.) will be determined for the design discharge, 50- and 100- year discharges estimated under Task 2 above. Results from the hydraulic analysis will be provided in both tabular as well as graphical output formats for the consultant team. Hydraulic Criteria: Chapter 800 of the Caltrans Highway Design Manual (HDM) delineates the hydraulic design criteria for bridges. The basic rule for hydraulic design is that bridges should be designed to pass the Q50 with sufficient freeboard and convey the Q100 without freeboard, except...
Hydraulic Analysis. CONSULTANT shall update the Redwood Creek HEC-RAS storm drainage model using site specific survey data. The model will be run using the 30-year event peak flow rate from the City’s Storm Drainage Master Plan, and the FEMA 100-year peak flow rate. CONSULTANT will review differences in box culvert sizing for these flow rates. If a design flow rate of less than a 100-year storm is used, CONSULTANT will review the overflow flow path of excess flows. CONSULTANT will prepare a design report that documents box culvert sizing and key design parameters verifying the design intent for the relocated box culvert.
Hydraulic Analysis. XxXxxxxx completed a hydraulic analysis considering various pipeline sizes and the downstream pipeline outlet elevation to determine the potential hydraulic capacity of the cold water intake. As outlined in the previous paragraph, two options were considered for routing the water supply pipeline through the dam: (1) Option 1 through the left abutment to a downstream outlet structure, and (2) Option 2 through the dam utilizing an existing outlet conduit. The analysis was completed assuming a reservoir operating range of 2588.0 ft to 2563.0 ft. The lower reservoir operating levels are only achievable if the pipeline outlet structure is moved downstream to a point where the pipeline invert elevation of 2555.0 ft could be provided (Option 1). The analysis was completed assuming both a trashrack box (Figure 1 and Table 1) installed on the intake pipe as well as full criteria fish screens (Figure 2 and Table 2). These figures assume the outlet structure is located downstream from the dam. In preparing this memorandum, it was assumed that the outlet structure would be located immediately downstream from the existing outlet conduit (Option 2). Using the existing outlet conduits restricts the minimum reservoir operating level to approximately 2565.0 ft since the existing conduit elevation is 2563.0 ft. Assuming a full criteria fish screen is provided, the maximum flow rate which could be expected from a 48 inch pipeline is approximately 160 cfs which occurs at a reservoir operating level of 2588.0 ft. Figure 3 and Table 3 presents the rating curve assuming a 48 inch pipeline fitted with an intake screen and the outlet structure at the dam. Figure 1. Rating Curve with Trashrack operating as Siphon Figure 2. Rating Curve with Fish Screen operating as Siphon Table 1. Siphon Conditions with Trashrack at Intake 48-inch Pipe with Trashrack Res. Head (ft) Flow (cfs) Pipe Velocity (fps) Velocity Head (ft) K Minor Losses (ft) Unit Friction Loss (ft/100ft) Sum HL at Dam (ft) Sum HL at Outlet (ft) Head at Dam Crest (ft) Head at Outlet (ft) 2588 172 14 2.90 5 14.5 0.95 24.0 25.0 0.3 5.0 2585 161 13 2.55 5 12.7 0.84 21.2 22.0 0.1 5.0 2580 141 11 1.95 5 9.8 0.66 16.3 17.0 0.0 5.0 2575 118 9 1.36 5 6.8 0.47 11.5 12.0 -0.2 5.0 2570 89 7 0.78 5 3.9 0.28 6.7 7.0 -0.4 5.0 2565 47 4 0.21 5 1.1 0.08 1.9 2.0 -0.6 5.0 2564 33 3 0.10 5 0.5 0.04 1.0 1.0 -0.7 5.0 2563 1 0 0.00 5 0.0 0.00 0.0 0.0 -0.7 5.0 42-inch Pipe with Trashrack 2588 131 14 2.88 5 14.4 0.96 24.0 25.0 0.3 5.0 2585 123 13 ...
