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Probable Maximum Flood (PMF) determination — New Don Pedro Dam, Turlock Irrigation District
Turlock, California
Like many federally-regulated dam owners, Turlock Irrigation District (TID) was recently directed by the Federal Energy Regulatory Commission (FERC) to re-examine their dam’s Probable Maximum Flood (PMF). Knowing that Mead & Hunt is known nationally for performing PMF evaluations that comply with FERC guidelines, they asked us to study their New Don Pedro Dam, on the western slope of the California Sierra’s. When the US Army Corps of Engineers (USACE) designed the dam’s physical and operational components – its spillways, reservoir volume, freeboard height, annual storage curve, and flood operation rules – they developed them to fit a specific PMF hydrograph. Our preliminary review of the HMR58 concluded that recalculating the PMF would likely result in a higher peak and volume than used in the original design. In the end, the generous freeboard allowances and spillway design that USACE had adopted were repaid. Mead & Hunt found that, although the PMF volume increased by 12 percent, and the peak inflow by 17 percent, the dam could still pass the PMF with over three feet of freeboard – thanks, in part, to TID’s resurvey of their dam’s crest elevations.
Dam failure analysis, inundation mapping — American Electric Power
Roanoke River, Virginia
With vast experience producing Emergency Action Plans using dam failure analyses and Geographic Information System (GIS)-based inundation maps, Mead & Hunt was the ideal choice to perform American Electric Power’s Dam Failure Analysis. We started at their Leesville Development on the Roanoke River, using the NWS-FLDWAV model to simulate dam failures and failure-induced flooding. For the Smith Mountain Dam, we simulated failures for an arch dam more than 200 feet high and impounding approximately a 43,000-acre reservoir, and the smaller Leesville dam. We chose the FLDWAV model for its ability to simulate the passage of the floodwave down a 100-mile stretch of the Roanoke River valley, including reverse flows in several tributaries along the affected reach. Combining model outputs with GIS-based map data and cross section information, we developed inundation maps showing inundation flood levels for both dams, which resulted in a series of 32 tiled maps for Smith Mountain and a series of 19 tiled maps for Leesville.
Comprehensive drainage plan — Reclamation District 1000, Natomas Basin
Sacramento, California
On the western slope of California’s Sierra Mountains, urban development has been soaring over the past decade, and doesn’t show signs of stopping any time soon. Not surprising, leaders of the Reclamation District 1000 were concerned about managing their growing population’s drainage needs. They called upon Mead & Hunt to create a comprehensive drainage plan that would support the growth in the Natomas Basin area, located in the Sacramento Region. Focusing on the northern section, we conducted extensive planning and hydrologic modeling to develop their plan. The model has provided an outstanding tool that helps them manage their growing drainage needs with confidence.
From planning to design
Having confidence in our team’s intimate knowledge of the basin’s drainage patterns, and our leading reputation for designing pump stations in the region, the Reclamation District 1000 asked us to design many of their drainage improvement projects, including their Plant 1 pump station. Plant 1 is the largest pumping plant in the district’s system, and plays a major role in driving their comprehensive drainage plan’s success.
Site selection and feasibility study — Friedman Memorial Airport
Wood River Valley, Idaho
The Friedman Memorial Airport 2004 Master Plan Update recommended preparation of a feasibility study to locate an alternative airport site location, since the existing airport was severely constrained. Due to our combined airport planning and GIS background, Mead & Hunt was asked to develop a GIS database consisting of more than 50 data layers representing environmental, transportation, natural resources, cultural, political, and historical information that was integral to analyses performed in the site selection process. From the 16 initial sites identified, three were chosen for more detailed study. Graphics and data analyses generated from the GIS aided in the clear and concise presentation of study results to both the general public, the Federal Aviation Administration and the client. With the GIS database, a far wider range of site location possibilities could be thoroughly addressed in a shorter time-frame than in previous studies, enabling the client to make timely and more objective decisions.
FERC re-licensing — Santee Cooper Hydroelectric project
Moncks Corner, South Carolina
When the South Carolina Public Service Authority ("Santee Cooper"), needed to begin updating their hydroelectric project’s license, they knew Mead & Hunt would be the ideal candidate. They valued our impeccable relationships with FERC, and state and local agencies across the country. They respected our track record of coordinating the process smoothly with owners and licensing officials. And, they knew that our extensive knowledge of the licensing process would enable us to recommend abbreviated versions that would comply with FERC regulations, but get the job done without unnecessary steps or costs.
We’re currently renewing their license that will expire in 2006, coordinating with the following agencies:
• South Carolina Department of Natural Resources
• South Carolina Department of Health and Environmental Control
• US Fish & Wildlife Service
• National Marine Fisheries Service
• US Army Corps of Engineers (owns associated facilities)
Water supply and socioeconomic impacts — El Dorado County Water Agency
El Dorado County, California
Across the country, rising populations and steady building are signs of strong, healthy economic growth. But, what happens when a community’s infrastructure can’t support ongoing development? More than a question, this is the potential reality California’s El Dorado County Water Agency (EDCWA) is considering. Recognizing the potential urgency of their situation, they turned to Mead & Hunt to perform a socioeconomic evaluation to examine how quickly a shortage could curtail their economic growth. While we weren’t surprised to learn that their fears were legitimate, we were all alarmed when our Socioeconomic Resource Impact Study revealed that a shortage could hault their growth as soon as 2010. The good news is that there are potential solutions.
We looked at the Upper American River Project (UARP), which is used mainly to generate electricity. Controlling the majority of El Dorado County’s watershed yield, UARP consists of 11 reservoirs, owned and operated by the Sacramento Municipal Utility District (SMUD). Our team identified that UARP’s facilities could be used to develop a supplemental water supply in EDCWA’s region. We continue to support EDCWA in its discussions with SMUD, hoping that we can provide the county with a much needed supplemental water supply using the UARP facilities.
