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Underwater Acoustic Remote Sensing For Predictive Maintenance Modeling of Dams

Kenneth J. LaBry Chief Scientist, Underwater Acoustics

We are now living in a time where robotics and remote sensing, are utilized to unburden human activity from risk exposure and repetitive effort as well as to provide cataloged and characterized information from remote sensing observation, which is used to make better decisions in all aspects of society from medicine to transportation and civil infrastructure. This paper proposes to implement a combined effort of robotics, remote sensing and digital data management for Predictive Maintenance modeling of dams.

There are 84,000 Dams in the United States, 1,756 of these are also hydroelectric power generating facilities. These Dams are an average of 52 years old. Most of these dams have unknown disposition of underwater components and un-mapped stages of degradation. The examination of any Dam is a singular exercise. Some Dams may be of similar design but no two Dams are quite alike with each Dam requiring a tailored examination plan. This paper presents a system and methodology for the application of high definition Underwater Acoustic Remote Sensing in the inspection of submerged dam structure components and the interfaces of those structures with the surrounding water bottom and shows how the information acquired can be presented in a platform that is of value to the owner-operator.

This paper demonstrates the pitfalls and problems associated with acoustics and sonar utilization in substructure inspection, the challenges inherent in shallow environments, confined spaces and difficult access, the environmental difficulties, cost-effectiveness, and benefits, as well as result capabilities.

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Application of Underwater Acoustic Remote Sensing for Underwater Examination of Trash Racks and Intake Screens

Kenneth J. LaBry, Chief Scientist, Acoustics, Underwater Acoustics International

 

Major industrial facilities from water resource dams to coffee processing and packaging plants all have the need to utilize water as a cooling source for the power sources of the mechanized automation that they use to provide the product that is their reason for existence. Some, such as hydroelectric plants and other types of electricity producers, have more complicated water intake systems. The operation of the facility is dependent on a properly operating cooling system. To maintain the operational capacity and efficiency of the cooling system, the inlet must be maintained in a clear high flow-through condition. This requires that the maintenance staff be able to determine when debris is accumulating at the inlet grating racks.

 

The periodic examination of submerged trash racks and intake screens for debris accumulation, filter grate or screen damage, and misalignment has typically required an intake shutdown and diving or ROV effort. The techniques used for examination are typically visual and tactile. In underwater conditions, they provide a limited and only a subjective ability to identify the field of view and detection and its location. This is largely impacted by inclement environmental conditions such as high current flow, significant hydrostatic pressure differential, and low to no visibility. These issues also present a significant safety hazard to divers and require either partial or facility shutdown in order to ensure the safety of participants performing the examination. Due to the significant impact of these environmental conditions on results and findings, as well as the safety of human participants, these surveys tend to be extremely subjective and provide sporadic coverage of the trash racks and intake screens. Even with the best efforts of the personnel and instrumentation involved, often there is too little information to be able to assess screen misalignments or localized damage. With the development of underwater acoustic imaging sonar systems based on steered beam sonar and profiling, remote sensing systems that have the ability to produce very high definition sonar imagery and very precise acoustic profile measurement, there is now a cost-effective alternative to conventional methods of underwater trash racks and intake screens as well as submerged pump cellars with confined space conditions. These underwater remote sensing examinations can provide a comprehensive spatial element representation of underwater structure surfaces and their interface with the water bottom.

 

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Application of Underwater Acoustic Remote Sensing Examination of Flooded Penstocks, Tunnels and Water Intakes

Kenneth J. LaBry, Chief Scientist, Acoustics, Underwater Acoustics International

Introduction

Large industrial facilities, from utilities producing electricity to manufacturing plants and chemical refineries, all have the need to utilize water for either power generation or as a cooling source for the power sources and machinery of the mechanized automation they use to provide the product that is their reason for existence. Some, such as hydroelectric plants and other types of electricity producers, have more complicated water intake systems. The operation of the facility is dependent on a properly operating cooling system. To maintain the operational capacity and efficiency of the cooling system, the inlet conduit must be monitored and maintained. This requires that the maintenance staff be able to determine when the gradual degradation due to the wear of use, causes issues that require remediation and repair.

 

 

 

The periodic examination of these intake conduits should be inspected at regular intervals to document the progression of wear and degradation. Currently, Fenstermaker implements the only commercially operated sonar capable of imaging the internal wall of a flooded tunnel or conduit and providing a spatially referenced high resolution image of these water conduits. The acoustic sonar sensors were built at Fenstermaker’s request and to Fenstermaker’s specification by the sonar manufacturer, Kongsberg Mesotech. To adequately inspect these water conduits by other methods, such as a walk-through, requires de-watering of the conduit or pipe and presents significant safety issues relative to confined space operations. Due to the significant impact of these environmental conditions on results and findings as well as the safety of human participants, these surveys tend to be extremely subjective and provide poor spatial documentation of recorded observations. With the development of underwater acoustic imaging sonar systems based on steered beam sonar that can be articulated to project down a conduit, penstock, tunnel or pipe, there is now a methodology that can provide a comprehensive spatial element representation of flooded water conduit surfaces.   The collected data can then be utilized for comparative analysis to previous examinations and utilized for predictive maintenance modeling.

 

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Application OF Underwater Acoustic Remote Sensing Dam and Impoundment System Examination Case Study Examples

Kenneth J. LaBry, Chief Scientist, Acoustics, Underwater Acoustics International

 

The advanced age of the Dam infrastructure in the United States and the general lack of attention that this infrastructure has received since beginning operation is requiring a comprehensive examination to provide information for evaluation of critical needs and to develop monitoring plans in order to acquire the analytical information for predictive maintenance. The following discussion relates the integrated process used for applying underwater remote sensing techniques and technology to the examination of submerged components of aging dam systems.

 

Case Study 1

Bayou D’ Arbonne Dam – Near Farmerville, LA

 

 

Fenstermaker, as team lead, was tasked with performing a comprehensive examination and inspection of the dam utilizing innovative technology in underwater acoustic imaging and profiling. To bring an added level of visualization and uniqueness to the project, Fenstermaker combined the data from High Definition Laser Scanning of the superstructure and surrounding land mass environment with the acoustically scanned substructure and water bottom. This resulted in a unique and comprehensive three-dimensional model of the dam system, including water bottom erosion patterns. Key observations during the course of this project were a water flow transiting through the dam spillway structure, indicated by the existence of two small holes in the sediment at the interface of the water bottom and the heel of the dam, and a corresponding high velocity water stream exiting near the lower dispersion blocks downstream and in alignment with the holes in the sediment.

 

 

 

 

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Underwater Acoustic Remote Sensing For Predictive Maintenance Modeling of Dams

Kenneth J. LaBry, Chief Scientist, Acoustics, Underwater Acoustics International

 

  1. Introduction

We are now living in a time where robotics and remote sensing, are utilized to unburden human activity from risk exposure and repetitive effort as well as to provide cataloged and characterized information from remote sensing observation, which is used to make better decisions in all aspects of society from medicine to transportation and civil infrastructure. This paper proposes to implement a combined effort of robotics, remote sensing and digital data management for Predictive Maintenance modeling of dams.

There are 84,000 Dams in the United States, 1,756 of these are also hydroelectric power generating facilities. These Dams are an average of 52 years old. Most of these dams have unknown disposition of underwater components and un-mapped stages of degradation. The examination of any Dam is a singular exercise. Some Dams may be of similar design but no two Dams are quite alike with each Dam requiring a tailored examination plan. This paper presents a system and methodology for the application of high definition Underwater Acoustic Remote Sensing in the inspection of submerged dam structure components and the interfaces of those structures with the surrounding water bottom and shows how the information acquired can be presented in a platform that is of value to the owner-operator.

The paper demonstrates the pitfalls and problems associated with acoustics and sonar utilization in substructure inspection, the challenges inherent in shallow environments, confined spaces and difficult access, the environmental difficulties, cost-effectiveness, and benefits, as well as result capabilities. It outlines the basic acoustic principles involved in the inspection of substructures, the development of remote sensing equipment capable of generating the necessary resolution and definition for shallow environments, as well as the development of the techniques and methodologies necessary for proper execution of substructure inspections and comprehensive shallow water-bottom surface mapping. The discussion also encompasses remarks regarding the economic and safety advantages of remote sensing in substructure inspections.

Case study examples are shown and briefly discussed. The examples depict integrated modeling capabilities for illustrating the inspection results, the utilization of reiterative modeling to track conditional changes and provide a knowledge-based predictive basis for maintenance and rehabilitation scheduling.

 

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