CDM FEDERAL PROGRAMS CORPORATION
DESCRIPTION: WEST POINT DAM AND LAKE, GA AND AL
DATA COLLECTION AND EVALUATION
-Collect, review, and evaluate available data for the three reservoirs including Geographic Information System (GIS) coverages of topographic data, existing models, reports/studies (such as the water control manuals [WCM] for the Alabama-Coosa-Tallapoosa (ACT) and Apalachicola-Chattahoochee-Flint (ACF) Basins).
-Evaluate the existing Flood Insurance Studies (FISs) and/or Flood Insurance Rate Maps (FIRMs) and available H&H models for the downstream areas for comparison with HEC-RAS hydraulic model results as provided by the USACE as available.
- Identify the needed FEMA data references and contacts for the USACE to acquire the data.
- Evaluation of the need to potentially update the probable maximum flood (PMF) rainfall data amounts for the three reservoir locations. Review historic and current rainfall amounts. Take the difference in rainfall amount and multiply it by the tributary area to each reservoir to conceptually estimate an increased inflow volume then superimpose this volume on the normal high pool (or maximum flood control pool as advised by the USACE) to estimate the potential increase in peak stage for the dambreak analyses. Advise the USACE if the PMF should be updated as a modification to this task order.
- Deliverables: Data collection and evaluation progress reports
RESERVOIR DAM FAILURE ANALYSES
? Process the required data to develop new hydraulic models to simulate flows from the three dams in a breached and non-breached condition. No hydrology will be simulated for the upstream tributary or downstream areas. Flows will be from the dam breaches and design discharge conditions only. HEC-RAS and GeoRAS will be used to setup and run the dam failure analyses. The hydraulic models will be applied to each of the three reservoirs at the main dam.
- Deliverables: A Reservoir Dam Failure Analysis Report for the project will be submitted to USACE. The report will include a summary of model results, summary tables of peak flows, stages, flood wave arrival time, and velocities by station (20 locations for this dam system).
INUNDATION MAPPING SUPPORT
- USACE will use the data provided to develop inundation maps for the dam failure scenarios for the reservoir. Provide to USACE the GIS coverages and base maps, and data generated (topographic data, depth grids, inundation boundaries).
- Use the output from the dam failure analysis to develop depth grids and polygons that define the limits of inundation for each scenario using HEC-GeoRAS for post processing. These depth grids and inundation polygons will be used later by USACE to develop the final inundation maps that go into the EAP. Also provide to USACE the ArcMap project files used to perform RAS post-processing (with associated data), and a printout of the inundation limits included in the report that describes the process of developing inundation limits and depth grids. This will include up to three map plates for this reservoir. This visual representation will assist USACE in reviewing the results of the RAS model to ensure that the USACE has the information to perform the inundation mapping to meet all requirements of the EAP.
- Deliverables: Provide model results, HEC-GeoRAS files, ArcMap files, and associated model data. Provide a Dam Failure Inundation Mapping Report for the reservoir to USACE. The report will summarize the data collection and evaluation, model set-up and dam failure analyses, and data and results for the inundation mapping.