Hydroelectric dams are impressive in both size and scale. Some of the tallest dams stretch over 300 meters tall and the longest dams span nearly 4 miles wide. The single largest reservoir in the world holds 180 cubic kilometers of water, which is roughly 47 trillion gallons, enough to provide the entire United States with water for nearly five months! It’s no wonder that hydro power accounts for 20% of the world’s energy. With such large structures comes a serious need for underwater inspections and preventative maintenance. Inspection class Remotely Operated Vehicles (ROVs) offer a great deal of support for routine dam inspections, including inspecting Face of Dam, Heel and Toe of Dam, Water Intakes, Trash Racks, Penstocks, Turbines, and Lower Outlets.
nDams provide a set of unique challenges for inspection. It’s a dangerous environment, with deep water, fast moving water, turbid outflows, turbines and other entanglements. It’s extremely dangerous and sometimes impossible for divers to inspect these areas while the dam is operational. Only ROVs with the most hydrodynamic design and highest levels of thrust can overcome the demands of dam inspections. Typically, an AC power system is required to keep the vehicle in continuous operation for long shifts or for heavy thruster use to counteract the current, which would otherwise deplete a DC battery system.
ROVs come equipped with a variety of sensors which are extremely helpful for dam inspections. Features such as HD Cameras, High Intensity LED Lights, Sonar, Laser Scaler, Thickness Gauge and Grabber Arm are used heavily. The Camera paired with LED Lights are used for visual inspection and documentation, and are especially useful in deep, dark waters along the bottom of the dam. Sonar is a critical tool for successful navigation in very turbid water where water clarity is minimal. A Laser Scaler emits two lasers at a fixed width, acting like a measuring stick, allowing for accurate measurement of objects by simply looking at them with an ROV. A Non-destructive thickness gauge is used to check the integrity of coatings and measuring corrosion. And a grabber arm can be used to clean trash racks of debris, or to retrieve foreign objects from the water around a dam.
By utilizing inspection class ROVs for dam inspections it eliminates the risk to divers, reduces the down time of dam operations, provides the ability to increase the frequency of inspections and perform preventative maintenance faster while reducing the per-inspection cost.
UUV Aquabotix Ltd (ASX:UUV) (“Aquabotix" or the “Company”) today introduced Live Remote Viewing, a new product feature that enables real-time underwater viewing and connectivity between Aquabotix’s products and remote customers via the cloud.
Live Remote Viewing, designed specifically for Aquabotix’s Endura ROV (remotely operated vehicle) and AquaLens Connect (networked underwater camera system), utilizes remote diagnostics to allow off-site customers to monitor multiple inspections, operations and explorations from a single platform in real time.
“The Internet of Things (IoT) is changing the way our world communicates and interacts, and we believe that same concept should apply under the water,” said Durval Tavares, Aquabotix’s CEO. “We’re helping to address our customers’ pain points by transforming a previously singular, disconnected entity into one where multiple underwater technologies can work together on the one platform. Utilizing the IoT to produce the world’s only digital inspection-class ROV platform, we are confident Live Remote Viewing will be a game changer in the world of underwater robotics and the start of many future cloud-driven innovations for Aquabotix.”
The Live Remote Viewing product feature is designed for use across a wide range of industries, including aquaculture and infrastructure. For the aquaculture industry in particular, which continues to grow exponentially, the feature will enable higher quality, more cost-effective inspections of fish farms. Customers will now have access to continuous live feeds from the Endura ROV that can monitor the condition of the fish and nets, inspect moorings and assess feeding habits to prevent overfeeding.
Live Remote Viewing is now available to all Aquabotix customers. Current customers will not receive an upcharge to utilize Live Remote Viewing, but are required to register an account with Aquabotix to access live, secure feeds through the feature.
For more information about Live Remote Viewing and other Aquabotix’s products, please visit www.aquabotix.com.
Tel: +1 617-275-6522
Water storage tanks are everywhere. Drive through any small town and you’ll see water towers dotting the landscape. Fly above any city and you’ll see water tanks on top of every skyscraper. We use an incredible amount of potable water. In fact, the US Geological Survey (USGS) estimates that on average, every American uses between 80-100 gallons of water per day, and an estimated 86% of the US population has access to public water. With so much infrastructure dedicated to providing a safe and constant supply of municipal water, it should come as no surprise that water tank inspectors are in high demand to keep our cities and towns running. Traditionally this meant sending divers for a dunk in your drinking water, however, inspection-class remotely operated vehicles (ROVs) are a great (and safe) alternative for potable water tank inspections.
Inspecting Water Tanks with ROVs:
When it comes time to clean, inspect or repair a water tank, it can be accomplished in two ways: with or without water. Tank inspectors and plant supervisors often prefer inspections and repairs to be completed while the tank is still full and operational. Draining a water tank is expensive, time consuming and wasteful. Draining also comes with the added risk of causing stress damage to the water tank, and leaves residents and businesses without water.
To do their job, tank inspectors must climb to the top of a water tower with all of their gear in tow, suit up in dive gear, and then squeeze down a port hole barely big enough to fit through to reach the subject of interest: our water. It’s easy to see why packing a small, portable ROV to drop into the tank can often be an easier and safer alternative. ROVs that run on internal DC battery power are the vehicles of choice for water tank inspection, because it means no generators or power cords need to be run to the top of the tank.
A live video feed is critical to quickly inspecting and documenting potential problems within a potable water tank. Problem areas such as welded seams, bolts, pipes, and gaskets can be checked for signs of corrosion. Lateral thrusters on an ROV allow an operator to move sideways along a horizontal seam or row of bolts for a thorough inspection. An ultrasonic thickness gauge, a form of underwater non-destructive testing equipment (NDT) is often mounted to an ROV, allowing an inspector to check the thickness of tank walls without harming the metal or metal coatings. Routine inspections and preventative maintenance are important steps to providing uninterrupted water service to nearby residents and businesses.
All water tanks will naturally collect sediment over time. As this sediment builds up, it must be periodically cleaned, similar to the bottom of a pool. This often involves sending a diver into the depths of a dark water tank with a large vacuum hose. The high intensity lights and high resolution camera on an ROV provide a good look at the bottom of the tank before and during sediment removal. Some underwater robots are even designed to aid in the cleaning process directly, further reducing the risks involved with prolonged dives.
Water tank inspectors are just a few of the unsung heroes who keep our country running. They risk their lives every day doing a job most people don’t even know exists. By using inspection-class ROVs, tank inspectors can stay a little bit safer while keeping our water clean and flowing.
Ask a remote-operated-vehicle (ROV) aficionado what industries these handy little tools have had the most impact on, and the answers will be varied and interesting. Some will immediately name fisheries and aquaculture, where ROVs let even small operators put mobile, flexible, sensor-enhanced eyes on even their most remote underwater operations. Others would favor the transportation industry, where ROVs make major contributions to port security and vessel hull inspections. Relatively few people, however, unless they had industry knowledge backing them up, would name one of the industries where ROVs have had a major and still growing impact: energy production.
To be sure, the energy market is an enormous and enormously varied set of operations, and it is true that ROVs play a small or nonexistent role in many of the industry’s subfields. Nobody expects ROVs to be a major player in coal mines, for example (though they are handy in investigating flooded sections of mine, a very hazardous condition where nobody wants to risk a human diver…)
There are three basic areas in which ROVs play a major role: installation and investigation of offshore windfarms. Installation and investigation of the hydraulic systems of nuclear plants, and inspections of dams – many types of dams, of course, but most relevant here are the major construction achievements that produce local electrical generating capacity, i.e. hydropower.
You may notice something rather fundamental about these three parts of the energy industry: they are all carbon-neutral or low-carbon energy production systems, and thus are important tools in reducing global warming.
Hydropower is among the oldest approaches to renewable energy, and is far older than its relatively recent adaptation to produce electricity. Preindustrial civilizations have used the power of running water to pump water uphill, to irrigate crops, and to turn machinery. In modern times, giant hydroprojects like the Hoover Dam produce thousands of megawatts of electrical power, enough to serve millions of households, at a relatively reasonable environmental cost. Unfortunately, while the Earth has plenty of water and plenty of gravity, the requirements of hydropower for particular configurations of these resources means that the generating capacity of the natural world is more or less known, and fixed – and the “good spots” are already taken. Hydropower produces more than 1,000 Gigawatts (that’s a thousand megawatts) – about a sixth of the world’s total generating capability. Because hydropower generally requires building large dams that hold enormous quantities of water – usually conveniently located just upstream of enormous population centers – the safety monitoring and maintenance of the dam system is of the utmost priority. ROVs, of course, bring the costs of maintenance and inspection down drastically, further increasing the economic sensibility of hydropower as one of the major components of the global energy economy.
In the eyes of many, nuclear power could not be more diametrically opposed to hydropower. But in fact, depending on your point of view, a number of fundamental similarities are clear. First, although neither hydropower or nuclear power are free of environmental costs, those costs tend to be fixed cost that arise from having the industry exist at all, not costs that double every time the installed generating base doubles. Second, both nuclear and hydropower are baseline generation systems, meaning that they are always available. Third, both forms of generation tend to have catastrophic, but extremely rare, failure cases. If Hoover Dam bursts, an entire downstream city will die. If a Soviet-era nuclear plant goes critical, half of Eastern Europe could be irradiated. This combination of low expenses, high reliability, and rare disaster cases encourage us to think of these forms of power as being *perfectly* reliable, when in fact they are anything but. How to push those systems towards increased stability? Again, with more frequent and more capable monitoring.
If hydropower is the revered ancestor, still trusted but unable to keep up with the demands of his hungry children, and nuclear power is the disliked but economically essential rich cousin whose fortune keeps the family from starvation, then surely offshore windpower is the angsty, emotionally involved younger sibling – a source of infinite potential and hope for the future that is, unfortunately, wrapped in often problematic presentation right now. Windpower has an enormously high undeveloped potential for power generation, at an environmental cost that is minimal if not negligible. (Just the surface layers of the atmosphere could generate 20 times the current TOTAL human energy usage.) Unfortunately, as with hydropower, the easy spots – that is, the places where a huge turbine farm isn’t out of place - are being used for other projects. And that means that wind power has to move offshore, where the real estate tends to be heavily discounted on account of being a thousand feet beneath the ocean. And although it’s possible for us to build infrastructure in the ocean on this scale, it’s not cheap and it’s not easy – and again enter ROVs, keeping costs down, keeping human divers out of harm’s way, and providing more information for project engineers about safety and performance.
It would be an exaggeration to say that without ROVs, we can’t get to a lower-carbon, warming-mitigated world economy. But it wouldn’t be an exaggeration at all to say that ROVs are making major contribution to the energy economy’s attempt to get us over the carbon-footprint hill and into the low-carbon, high-energy promised land.
One of the most common uses for commercial underwater remote-operated vehicles (ROVs) is in conducting inspections of water tanks, ship hulls, and submerged infrastructure such as bridge components or dams. A critical element of these inspections is measuring the thickness of metal components like hulls or girders. How do ROVs conduct this type of measurement?
On the Aquabotix Endura line of high-performance commercial ROVs, we offer the Cygnus NDT Metal Thickness gauge as an optional accessory. These gauges use ultrasound technology to measure the thickness of metal objects underwater. By emitting an ultrasonic beam into the surface of the metal and analyzing the return sound, the Cygnus NDT can measure metal of thicknesses up to 10”, even through coatings such as paint up to 0.787” thick.
The Cygnus NDT is extremely easy to use. The included CygLink software allows the ROV operator to visualize the tool’s measurements remotely on the video feed. To make things even easier, the optional Cygnus Probe Handler automatically aligns the probe to the wall or item being measured, with 15 degrees of movement, even if the operator has not perfectly approached the measurement subject.
Tools like the Cygnus greatly enhance the utility of our Endura ROVs. As ROVs take on more responsible roles in things like underwater inspections, the need for tools such as the Cygnus will continue to grow.
There are almost 80,000 dams in the US Army Corps of Engineers National Inventory of Dams (NID), and that isn’t even a comprehensive list; the NID only covers dams which reach a minimum height and which hold back a minimum volume of water. There are many thousands of other dams, on private and government land, which are used for irrigation, flood control, aquaculture, drinking water, industrial use, and a myriad of other applications. Although most of these dams are extremely useful, they can also pose a serious danger to people and objects downstream of the dam. For obvious reasons, dam failure can have catastrophic consequences.
Accordingly, it is critically important that dams be inspected on a regular basis. The federal government, via the Federal Emergency Management Agency (FEMA), provides guidelines for inspections on dams under federal control. These guidelines suggest that dams should receive an informal “eyes-on” inspection as needed or following any significant incident at a dam (such as a flood, an earthquake, or vandalism), as well as a more thorough intermediate inspection of the dam and all related structures on an annual basis. Federal guidelines also suggest a formal full inspection of the dam be carried out at least every five years, with a full special inspection to be conducted when there is a major event such as a large flood or a major earthquake. Around 3,200 dams in the United States are owned outright by the federal government, and another 5,200 or so are not owned by the government but are located on government land. Although there are some complications about the regulation of those non-federally-owned dams, all told about 10% of the largest American dams fall under the federal guidelines.
The remainder of the dams in the United States are regulated by the state governments, with the notable exception of Alabama which leaves dams essentially unregulated. The state laws and regulations are a fairly diverse patchwork; some states require inspections to be paid for by the dam owners, while other states put that expense on the taxpayer. A few states like Texas do not have a formal inspection schedule at all (although inspections are strongly suggested) while most states have stringent schedules and extensive systems of classifications for which kinds of dams must be inspected and how often.
In general, however, in most places, dams are supposed to be inspected at intervals ranging from annually to every five years. The size of the dam’s impoundment (the volume of water the dam is holding back) and the population of the area in the dam’s potential flood area are the major factors determining how often and how stringent such inspections must be. Again depending on the location, inspections can be carried out by divers or by surface inspection, usually with at least some underwater work being required. Clearly, there is an astonishingly large amount of inspection work called for in the dam safety regulations.
ROVs play a major role in accomplishing the difficult task of inspecting dams while leaving them in service. Many dams are simply not able to be “turned off” so that an inspection can take place. Even when dams are equipped with the ability to dewater areas for inspection or repair, such dewatering is time-consuming and expensive. ROVs and human divers are able to work in areas of the dam without having to go through the dewatering process, saving large amounts of money.
One area where ROVs have saved enormous sums for dam owners is in assessing the need for cleaning of trashracks, reservoirs, and head ponds. Rather than adhering to a calendar schedule for the dredging of such ancillary dam components, an ROV inspection using sonar can inexpensively check whether an area needs to be dredged at all.
Of even more importance than saving money is saving lives. At many dams, particularly hydropower dams, there are areas where it is very dangerous for a human diver to enter the water. High water flows and high pressure differentials can be life-threatening conditions. The use of an ROV allows dive teams to conduct preliminary safety assessments, measuring flow, depth, and water temperature before ever putting a human being into the water. ROVs have also been used to check safety concerns such as the open or closed status of a head gate, where a gap of a few inches in a nominally “closed” gate could pose a lethal risk to a diver in the area.
At large dams with deep water areas, ROVs have the ability to work deeper than human divers without needing mixed-gas equipment. (Divers going below 30 meters require decompression tanks and other specialized equipment that make a dive more expensive.) By using divers for shallow work at a dam, and ROVs for the deeper dives, a cleaning or inspection process can be accomplished at much less expense. In addition, ROVs can conduct survey work using tools such as multibeam sonar more efficiently than human dive teams. As dam infrastructure ages, inspections of components like downstream draft tube slabs require a great deal of precise surveying work to assess the condition of the slab.
As in many other areas of underwater work, ROVs are capable of making a large contribution to the jobs being done by human divers. ROVs make underwater work safer, more effective, and less expensive.
Check out the HydroView Pro inspecting a separation tank. The walls, pipes and sediment levels were observed. Pay close attention to the end of the video where the bottom skids of the HydroView were used to evaluate the depth of the sediment - just another example of an innovative way to use an ROV.
Thermal stratification in potable water storage tanks poses risks for system operators and their customers. Water treated with chlorine or chloramines generally remains stable for a few days. Thermal stratification can hamper passive mixing or cycling of the water resulting in the potential for limit aging or deterioration of the disinfectant chemicals. Drops in residual chlorine can lead to growth of bacteria often requiring the draining and flushing of the tank.
Thermal stratification can also promote the formation of nitrates and other disinfection byproducts, allow for the formation of ice endangering coatings and tank walls and allow headspace temperatures to rise above recommended levels.
The HydroView Pro 5MWI is equipped with depth and temperature sensors. Data from these sensors is recorded during tank inspections and downloaded following the inspection in an easy to read/report format. Additional water chemistry sensors are available and can be integrated with the vehicle and the data reporting module.