R&D Forum

EPRI releases report on trash and debris management

EPRI announces availability of a new report that examines practices and problems associated with trash and debris at hydropower installations. The report is titled Hydropower Technology Roundup Report: Trash and Debris Management at Hydroelectric Facilities.

In some cases, sizable operating expenditures are required to manage trash and debris at hydro facilities. The goal of this report is to assist hydropower operators to evaluate trash and debris management procedures and to make appropriate decisions regarding equipment investment.

EPRI surveyed the trash and debris management practices of hydropower producers, including investor-owned utilities; cooperatives; and federal, state, and municipal power agencies. EPRI conducted additional follow-up discussions with selected respondents.

The report presents:

  • – Background information on trash and debris management;
  • – Discussion of recent trash-related literature;
  • – Survey and follow-up results;
  • – Case studies showing good practices in trash/debris management; and
  • – Recommendations for research, demonstration projects, and improvements in trash/debris management.


EPRI estimates that relatively modest improvements in trash and debris management could be worth more than $500 million per year in terms of increased electricity generation at facilities in the U.S. and Canada.

– To order this report for $5,000, contact (1) 800-313-3774; E-mail: askepri@epri.com. Or visit the Internet: www.epri.com and search for “debris management.”

Sockeye survival increases in second year of study

Survival of juvenile sockeye salmon passing the 1,287-MW Rocky Reach Dam on the Columbia River in Washington increased in 2006 by as much as 5 percentage points. In the second year of testing of route-specific survival, Chelan County Public Utility District (PUD) estimated overall project survival (tailrace of the next upstream dam to the tailrace of Rocky Reach) at 93.3 percent. Route-specific results are: dam survival 95.3 percent, turbine survival 96.6 percent, and surface collector survival 99 percent.

In 2006, Chelan County PUD tagged 3,000 juvenile sockeye salmon with acoustic tags and released the fish upstream of the project. The utility used hydrophones (underwater microphones) to track the fish and develop estimates of survival and route-specific passage.

Survival in 2006 increased for all three passage routes when compared with 2005. In 2005, dam survival was 92.8 percent, turbine survival was 91.3 percent, and surface collector survival was 95.3 percent. Chelan County PUD believes both an improved predator
control program and the high turbidity in the Columbia River in 2006 likely played a role in the increased survival. Turbidity would make it more difficult for predators to locate and eat outmigrating smolts.

Of the three routes, turbine passage was used by a high proportion of sockeye (51.4 percent) and showed relatively high survival (96.6 percent). The surface collector continues to be the most effective non-turbine passage route. About 43.5 percent of sockeye used this passage route, with 99 percent survival.

This project is intended to investigate methods to increase survival of sockeye at Rocky Reach to meet habitat goals defined in Chelan County PUD’s Habitat Conservation Plan. The plan calls for a three-year 93 percent average survival standard. Steelhead and yearling chinook have already either met this goal or are very close.

In 2007, Chelan County PUD will perform multiple releases of acoustically tagged sockeye to investigate opportunities for increasing survival through the turbines, as well as passage through the surface collector.

Model will predict reaction to dam break during winter

If a dam breaches during winter, ice cover in the river and frozen conditions in the flood plain could significantly affect both the flood wave speed and amplitude. However, current dam break simulation computer models focus on breach events occurring during open water conditions. To better predict the results of dam breach during winter, researchers are developing a Unified River Ice Breakup Model.

The wave speed and amplitude of a flood resulting from dam break during winter months could be significantly affected by a variety of unique conditions, says Brian Morse, a researcher with Université Laval in Québec, Canada, who is heading the team developing the model. These include:

  • – In the flood plain, the ground would be frozen, tree and brush conditions would be different, and snow would contribute to the flood wave;
  • – Ice cover in the river may retard the wave, making it steeper and slower to attenuate; in addition, resistance to flow will decrease as the ice cover breaks up, increasing the channel’s capacity and providing a positive feedback loop with the flood wave;
  • – Under special conditions of weak waves combined with exceptionally thick and strong ice covers, a pressure wave may travel down the river and significantly increase wave speed; and
  • – Breakup of the ice cover will add ice debris to the wave, which could get impeded and form an ice jam; this temporary dam could then break up, resulting in the flood wave growing to new levels as it travels downstream.


To develop this model, researchers are carrying out laboratory and field work to get a better understanding of the fundamental processes. Current work involves:

  • – New formulation of equations for non-hydrostatic pressure flows;
  • – Developing and updating ice failure criteria;
  • – Developing a debris model using smooth-particle-hydrodynamics numerical methods;
  • – Modeling submergence of ice criteria using a three-dimensional numerical model;
  • – Converting an open-channel finite volume numerical model into one that can interface with the ice failure criteria and the debris model; and
  • – Building integrated models that simulate the integrated processes.


Other participants in this research include the University of Alberta, Hydro-Québec, école Polytechnique de Montréal, State University of New York at Cobleskill, Alberta Environment, Environment Canada, and BC Hydro. Financing comes primarily from a grant from the National Science and Engineering Research Council in Canada, with support from Hydro-Québec.

– For more information, contact Brian Morse, E-mail: brian.morse@ gci.ulaval.ca.

CEATI publishes report on detecting, cleaning up SF6 gas

CEATI announces availability of a report about detecting and cleaning up sulfur hexafluoride (SF6) gas if it leaks from switchgear. The report is titled Safety Protocol for the Detection and Cleanup of SF6 Gas and SF6 Gas Decomposition Products in Buildings Following Catastrophic Failure of SF6 Gas Insulated Switchgear.

Switchgear are located in areas where electrical equipment may need to be isolated. This includes generators, motors, transformers, and substations. Many hydro facilities are moving to SF6-insulated switchgear because the high dielectric strength of SF6 allows for significant reduction in the size and cost of breaker equipment, with increased reliability when compared with other switchgear, says Alastair M. Wilson, technology coordinator for CEATI. However, SF6 gas displaces oxygen. In addition, its decomposition due to electric arc heat can cause SF6 to break down into potentially toxic by-products, Wilson says.

This report was developed by CEATI’s Life Cycle Management of Substation Equipment and Apparatus (LCMSEA) interest group.

The report contains results from two phases:

  • – Phase I: Compilation of background and references in support of a safety protocol for the detection and cleanup of SF6 and SF6 decomposition products, in the event of a catastrophic failure involving indoor gas-insulated substations. This phase also identified the latest field methods for detecting SF6 and SF6 decomposition products.
  • – Phase II: Development of a safety protocol for detecting and cleaning up SF6 and SF6 decomposition products, including the protocol for entry into affected areas and the training and protective equipment required for personnel to restore the substation to a safe working environment.


The report also compiles the nature of decomposition products generated from the thermal decomposition of SF6 gas, based on case histories of previous incidents.

– For more information or to purchase this report, contact (1) 514-866-5372; E-mail: publications@ ceatech.ca.

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