One of the biggest benefits we offer for FERC licensing and compliance is our people. Nationally renowned engineers and biologists work with you to develop the best practical approach to successfully negotiate the licensing process and meet the requirements of your existing FERC license. We complement laboratory studies with field studies and research to give you the most balanced results.

Because our staff has extensive experience with FERC licensing and compliance, we can work with you to develop your FERC license application, capacity amendment application, study plan, and exhibit drawings. In addition, we provide:

  • Feasibility studies
  • Detailed design
  • Construction oversight
  • Economic analysis
  • Energy optimization
  • Hydraulic evaluations
  • Due diligence evaluations
  • Modeling
  • Field measurements

We have conducted numerous hydraulic model studies of hydroelectric stations and related structures such as intakes, outlets, spillways, stilling basins, fish ladders, and navigation locks. In addition to providing physical hydraulic and computational fluid dynamics (CFD) modeling for your hydropower design and retrofit, we have worked on fish passage facilities, total dissolved gas (TDG) abatement, compliance with ESA regulations, dam safety analysis, risk reduction and remedial design.

Featured Projects

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ALDEN conducted a comprehensive, multi-faceted flow model study of the addition of a proposed powerhouse (including three turbines) at the Meldahl Locks and Dam facility on the Ohio River.   Meldahl Locks and Dam are operated by the Huntington District of the U. S. Army Corps of Engineers (USACE) for navigation.   As part of the powerhouse design optimization, Alden studied the effect of the power house addition on flow conditions in the approaches.  Flow patterns approaching the powerhouse were also evaluated to ensure optimum turbine performance.

Alden designed, constructed and tested an undistorted, 1:120 scale comprehensive riverine model physical that included approximately 17,000 ft of the Ohio River.  The model was used to evaluate and minimize the impact of the hydropower project on navigation. 

In addition to the physical model, a 3D CFD model of the powerhouse intake was coupled with a 1:40 scale model of the intake canal and powerhouse structure to evaluate excavation requirements and ensure favorable flow patterns at the power house intake for increased turbine life and efficiency. 

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A 1:120 scale comprehensive riverine model physical of approximately 17,000 ft of the Ohio River helped to evaluate and minimize the impact of the hydropower project on navigation. 
Civil Infrastructure
Meldhal Lock & Dam

A 1:120 scale comprehensive riverine model physical of approximately 17,000 ft of the Ohio River helped to evaluate and minimize the impact of the hydropower project on navigation.

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During periods of spill, Cabinet Gorge Dam was generating total dissolved gas (TDG) concentrations in excess of water quality standards. Through a series of feasibility studies, design evaluations, retrofits and/or modifications, Alden engineers worked to help Avista Corporation meet their FERC licensing requirements for the hydroelectric project located in Idaho on the Clark Fork River.

In early studies, the Alden team performed a 1:50 scale physical hydraulic model study to investigate re-commissioning of diversion tunnels used during construction of the project as bypass tunnels to pass spill flows at lower TDG levels than are generated during spillway operation. Studies revealed that the reduction in TDG afforded by the bypass tunnels was less than originally expected.

Additional feasibility studies were conducted to evaluate two alternatives for TDG reduction. One idea was the creation of off-stream “gas stripping” channels downstream of the dam, which ultimately proved to be fish passage un-friendly. Ultimately, modification of the existing spillway crest was found to be most feasible.

Full hydraulic and structural engineering services from feasibility through design and construction have been completed for the modifications to five of the eight spill bays in order to reduce TDG. Construction plans and specifications were prepared, and documentation for submittal to FERC was produced. Alden also provided construction technical support.

In addition to the work done to reduce TDG, Alden engineers also performed several structural projects for Cabinet Gorge Dam:

  • A Stoplog Deployment Crane was designed and fabrication-level drawings developed for the deployment crane system for lifting 10-ton stoplogs. The steel frame was designed to allow assembly and disassembly at each of the eight spill bays. Performance specifications for the 15-ton top running hoist were also provided
  • The FERC Supporting Technical Information (STI) Documents were reviewed and updated for Section 6—Hydrology/Hydraulics and Section— Stability/Stress Analysis.

In further compliance measures, the development of a fish trap design in the project tailrace for the expedited transmissivity of ESA listed bull trout past the project was supported. This effort also used the 1:50 scale model for initial site selection studies. Alden also provided a fisheries and hydraulic engineering representative on a “panel of experts” who advised on the best approach for trap site selection and design. Computational Fluid Dynamics (CFD) modeling of the project tailrace was performed to confirm satisfactory location and performance of the selected trap design. The CFD model developed for the fish trap studies also confirmed compatibility of the TDG mitigation measures with the fish trap operations and to guide future development of the TDG mitigation.

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Dive in Deeper

Read more about Total Dissolved Gas at High Head Dams in this three-part blog series.

  1. Improving Water Quality: Total Dissolved Gas (TDG) Production at High Head Dams [Part 1]
  2. Air Supply Ramps and Cavitation: Total Dissolved Gas (TDG) Production at High Head Dams [Part 2]
  3. Energy Dissipating Devices: Total Dissolved Gas (TDG) Production at High Head Dams [Part 3]
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A view of the Cabinet Gorge Spillway
Civil Infrastructure | Natural Resources & Environmental Planning
Cabinet Gorge Dam Total Dissolved Gas (TDG) Spillway Modifications

This project involved structural engineering services from feasibility through design and construction for TDG modifications to five of the eight spill bays at Cabinet Gorge Dam.

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The Cedar Cliff dam and hydropower project is located approximately six miles from Cullowhee, in Jackson Country, North Carolina. The dam and hydroelectric facility is owned by Duke Energy and is located downstream of three other hydroelectric projects that are operated as a system.

The primary spillway includes a Tainter gate and the existing auxiliary spillway system includes two fuse plug sections (with different crest/activation elevations).  It was determined that the combination of the primary and auxiliary spillway systems were not adequate to safely pass the regulatory-increased Inflow Design Flood (IDF). The construction of a Hydroplus Fusegate system with six semi-labyrinth Fusegates in an enlarged auxiliary spillway channel was selected to increase spillway capacity to safely pass the new IDF which is now the full Probable Maximum Flood (PMF). 

Two reduced scale physical models were constructed to determine the required size of a ventilation system for the proposed Cedar Cliff Fusegates and headpond and tailwater levels at each Fusegate for flows up to the sixth Fusegate activating. The tailwater levels were required for design of the Fusegate ballast system.  

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Model testing looking upstream
Civil Infrastructure
Cedar Cliff Spillway

Physical model study to determine hydraulic performance of a proposed auxiliary spillway system during flooding events