Holyoke Hydroelectric, Hadley Falls Station
Alden’s engineers and biologists conducted extensive CFD modeling and biological evaluations to help the Holyoke Gas & Electric Department (HG&E) develop an effective downstream passage solution for endangered shortnose sturgeon at the Hadley Falls Station on the Connecticut River. The results of these studies produced engineering and hydraulic design criteria for an exclusion rack and downstream bypass. The CFD modeling examined flow conditions for several alternative rack designs, as well as the bypass discharge to ensure safe downstream passage of fish and minimal interference of upstream migrants trying to locate the entrance to a fish lift. Alden also developed conceptual designs and preliminary cost estimates for the preferred alternatives and conducted biological testing in a large laboratory flume with various configurations of bar racks and bypass entrance designs with juvenile shortnose sturgeon. Agency acceptance of the final design was obtained by HG&E after Alden completed a desktop analysis of total downstream passage survival using the laboratory bypass efficiency data and theoretical estimates of turbine survival.
Capability
Natural Resources & Environmental PlanningServices
Fish Passage Design, Modeling and TestingFish Protection Design, Modeling and Testing
Related Projects
As part of project/dam surrender and removal efforts at the Saccarappa Hydroelectric Project (Saccarappa), Alden provided S. D. Warren Company d/b/a Sappi North America (Sappi) with the final design and fish passage analysis for nature-like fishways in the upper channels at Saccarappa Falls. The final design involves reshaping the existing bedrock channel into a form that is more conducive to fish passage while mimicking the morphology of a natural bedrock channel. Alden provided agency consultation while developing the design and will ultimately provide construction support. The proposed design complements a proposed double Denil fishway over the lower portion Saccarappa Falls designed in partnership with Acheron Engineering.
Alden conducted a site visit and reviewed existing geotechnical, hydrologic, site constraints, and other site data prior to developing the final design for the nature-like fishways. The final design was achieved by way of iteration between a 3D CAD representation of the proposed bathymetric surface and a 3D computational fluid dynamics (CFD) model. Expected small-scale roughness of the channel bed was incorporated into the CAD surface through a novel texturizing technique based on a high resolution laser scan of the existing bedrock surface. The CFD model was used to simulate proposed conditions at four discrete design flow rates. Hydraulic data output by the CFD model (e.g., depth and velocity) informed subsequent improvements of the proposed surface in CAD. Sappi and agency review and feedback was provided at 30%, 60%, 90%, and final drafts of the design. Fish passage effectiveness of the final design was analyzed by Alden biologists and engineers using USFWS’s SMath models developed for assessing velocity impediments by estimating fatigue, survivorship, and work. Alden also provided engineering consultation and inspections to support project construction.
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Civil Infrastructure | Natural Resources & Environmental Planning
Saccarappa Falls Nature-Like Fishway Modeling and Design
Innovative 3D CFD modeling was used to design a fishway to mimic natural bedrock following removal of tow spillway dams.
A major component of an Atlantic salmon population model developed by NMFS is the survival of smolts and kelts passing downstream at hydropower projects. To obtain this information, NMFS contracted Alden to estimate downstream passage survival of Atlantic salmon smolts and kelts at 15 hydroelectric projects on Maine’s Penobscot River and its tributaries. These desktop survival estimates focus on direct mortality attributable to passage at dams and to multiple dam passage. An established turbine blade strike probability and mortality model was used to estimate direct survival of fish passing through turbines at each project. Survival rates for fish that pass downstream over spillways or through fish bypass facilities were estimated based on existing site-specific data or from studies conducted at other hydro projects with the same or similar species. Most of the projects included in the study have upstream passage facilities for anadromous species (river herring, American shad, and/or Atlantic salmon), as well as operating downstream bypasses for juvenile and adult outmigrants. Some of the projects have installed narrow-spaced bar racks or overlays to reduce fish entrainment through turbines.
The results of Alden’s survival analysis provided data in a level of detail that would have been extremely expensive and difficult to accomplish with field studies. Typically, turbine passage survival studies conducted in the field only evaluate one or two turbines operating at one or two gate settings (i.e., flow rates). The methods and model developed for NMFS for Atlantic salmon on the Penobscot River are transferable to other river systems and species. The theoretical model for predicting strike probability is applicable to most species and the blade strike mortality data for rainbow trout are considered representative of many other species.
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Natural Resources & Environmental Planning
Using Turbine Survival Models and Existing Data to Understand the Impacts of Hydropower Projects on an Endangered Species
Using Turbine Survival Models and Existing Data to Understand the Impacts of Hydropower Projects on an Endangered Species