A Visit to Hoover Dam: An Inside Tour of an Architectural and Engineering Marvel
An industrial wonder of the world, Hoover Dam is a concrete arch-gravity dam in the Black Canyon of the Colorado River, located near Boulder City, Nevada, on the border of Arizona. Constructed between 1931 and 1936 during the Great Depression, it was originally known as Boulder Dam. It was officially renamed Hoover Dam, for President Herbert Hoover, by a joint resolution of Congress in 1947.
The Pump Engineer team traveled from Las Vegas to Hoover Dam—one of 20th century’s most significant ar
The Black Canyon and nearby Boulder Canyon had been evaluated for their potential to support a dam that would control floods, provide irrigation water and produce hydroelectric power. Thousands of workers were involved in the construction of the engineering feat. Despite being an industrial first, as such a large concrete structure had never before been built, the project was completed more than two years ahead of schedule and the dam was turned over to the federal government on March 1, 1936. While still a major energy supplier, Hoover Dam is also a major tourist attraction, welcoming nearly a million people each year.
Taking in the scenic Nevada landscape, we were excited for the opportunity to tour the dam to learn about its engineering and architectural John Jorgenson, Weldshop Foreman and Douglas Hendrix, a Bureau of Reclamation Public Affairs Specialist, in a scenic office overlooking Lake Mead—the largest man-made reservoir in the country by potential integrity. We met with volume capacity – which was built alongside the dam. The lake now serves as a reservoir to the dam and is an integral part of all the functioning’s of the structure. Hendrix commented, “We are at 41% capacity now in the reservoir. We had over a 100% precipitation this year, so our recovery will be decent, but after 19 consecutive years of drought, it is going to take more than one good, above average snowfall or precipitation year here to get back to the full recovery of these reservoirs.”
The dam was a phenomenal feat at the time of its completion. “It is considered one seven greatest industrial marvels of the world,” Hendrix stated. The facility has more than 17 generator units, and when at full reservoir capacity, the dam can generate a solid 2500 megawatts of electricity—just enough power for over 1.5 million households. Due to the current reservoir capacity and a droppage of the centrifugal force of water at the penstock, the plant is able to maintain about 75% of the structure’s capacity.
Jorgenson himself has come a long way throughout his career. He worked as a journeyman, working in cavitation repair—which is damage caused in turbines due to rapid changes of pressure in a liquid leading to the formation of small vapor-filled cavities. Jorgenson also gained experience working for several years at Parker and Davis dams, both located downstream from the Hoover Dam.
Jorgenson oversees leading the maintenance at the power plant. He and his crew take care of the spillways, the intake towers, maintaining piping systems, etc.
For a structure over 80 years old, repairs play a big role in the upkeep of the dam. As the plant needs constant maintenance, due to its age, technicians are constantly replacing turbines, transformers, valves, pipelines, hoses, and other accessories. “We deal with quagga mussels, a mussel species indigenous to Africa. They grow exponentially and they are found in the piping systems, cooling systems, trash racks and almost any other place with exposed metal. They really love dams,” expressed Hendrix. “What we have been trying to do is work with a number of private biological control companies to develop quagga mussel control agents that we could add in the water that will help with the problem. We also employ other measures like ultraviolet microfiltration and physical cleaning of the piping and valves to get rid of accumulated quagga mussel shells.”
Due to the size and complexity of the plant, the improvement and maintenance process for leaks, welding, repairing and replacement of pipes and valves is constant. Since the commencement of his employment, Jorgenson has made many alterations to the plant. “I have changed the way we weld, the installation process for valves and even the type of valves we pick and choose. We now use more TIG and gas shielded flux core. We weld a lot of pipes and the main pipe we deal with is schedule 80.”
Jorgenson explained how many of the machines and parts in the structure have been in use for a long time. “The biggest cause of failure is just age. The machinery in the dam itself, has been in working since the 1930s and many parts, including valves have been running for more than four decades,” he said.
A frequent problem the plant runs into is obsolescence of older parts. If a situation arises where an unavailable part is required, it is typically replaced with an updated item, “What I am often doing is putting in a ‘back’ on a gate valve, which makes it a modern valve,” explained Jorgenson. “We are constantly trying to modernize and update everything in this plant.” To facilitate the upkeep of the plant regular outages are scheduled—generally starting on October 1 until the last day of April.
“As we upgrade the turbines and related infrastructure at Hoover Dam, we integrate the latest technological features and designs into our generators to reduce the degree of cavitation within the system in order to dramatically increase the life of our other structural components”, said Hendrix.
“You have to understand that this plant is huge and stuff does not just happen overnight,” stated Jorgenson. “We are constantly updating the plant and every time we do a major overhaul, we put in the latest technology. So these parts that you see are nothing like they were in the 1930s.”
“As the federal government, we understand the need to be judicious with money, so when we upgrade the plant, we know we are looking for parts that offer redundancy, longer life expectancies and the best value,” explained Hendrix. “We do not always look for the cheapest part, nor do we look for the most expensive part, but we definitely look at all the specs and the life cycle. We want products that will last multiple years through all kinds of different conditions.”
The process to have parts selected is a meticulous one. All the components have to pass through the electrical and mechanical supervisors and foremen. The dam performs a number of quality checks, and will reject parts if they are not up to the standards or do not promise quality and longevity. Hendrix commented, “The region’s engineering division gets together with Hoover Dam’s apprenticeship group to review the specs of a part they will replace as they are very stringent as far as quality control is concerned. We would rather pay a little bit extra for quality and have a product last a long time, rather than replace it.”
Rather than exclusively using an approved manufacturers list, Jorgenson highlighted that they generally use General Services Administration (GSA), which is a government entity. “If I need 25 12-inch Garbowsky class 300, then I go to our shop and tell them what I want,” Jorgenson stated. Hendrix added, “What is a little unique here, is that we still do most of our own in-house maintenance, as it is a self-sustaining facility; the money we get from the power sales pays for the structure. We also maintain a physical technical staff here to do repairs.”
Valves at the Dam
Touring the plant, some of the older technology in the piping systems and a significant amount of valving is evident. Hendrix explained that the plant piping systems use primarily gate, globe, ball and butterfly valves with an average 12-foot diameter and mainly maintenance is on 24 inches down.
One of the main applications of the valves in the plant is that they direct the water in one intended direction. “You do not want the water going back to where it is not supposed to,” Jorgenson said. The water coming down the penstock goes to the butterfly valve, where they have what is called a ‘bypass’—this ensures that too much water does not collect on one side. This essential process is achieved through the installation of 12-inch guard valves, check valves, ‘bypass’ and piping. Jorgenson and his team took a month and half to replace all the working parts in the area, some of which had been running for 40 years.
Jorgenson explained that the pipe crew had recently finished installing twelve, 12-inch swing check valves. “There are many types of valves here, everything that you can imagine, right from old-fashioned gate valves to globe screen check valves.”
Although there are a number of pumps used throughout the plant, the pumps that Jorgenson deals with most frequently are the sump pumps. As they can generally move anywhere from 18 to 20,000 gallons of water per minute, vertical sump pumps are used to drain excess water. “We had some divers come in here and pull off the new 16-inch guard valve that we have put in the sumps to close it off. Anytime there is excess water draining it goes down the sumps, is then filtered and then the pumps move it out here,” he said.
Jorgenson explained that other pump related activities, like oil transfers is taken care of by the preventative maintenance team. One of the biggest problems with working with the pumps is going down into the sumps. “I think that the last time somebody went down to the sumps at the bottom and drained all the water was 30 years ago,” Jorgenson reflected.
The dam itself produces its own free power through a couple of pelton wheel turbines. Jorgenson explained that, “This type of pump is really just another valve. They are pumping units that have buckets in them, and a jet of water sprays against it and turns it. The peltons have a needle valve in them which is very high-pressure which operates depending on how much water you want to push against the runner. They are very quiet units and are very cool. They are my favorite units.”
The next phase of our tour took us 705 feet below ground in a beautiful ornate brass and marble elevator. The total depth of the facility is 726 feet with a width of 660 feet. The generator room, located far beneath the ground, was one of many additional areas we had the opportunity to see. The room houses nine generators – A1 through A9. At the time of our tour, generator “A2” was the only one running. The upper penstock affects A1, A4, A6, A8 and A9, while the lower penstock affects A2, A3, A7 and A5. The primary function of all the generators is to generate electricity from the water as it flows downstream. The dam’s generators provide power for public and private utilities in Nevada, Arizona, and California. “The Bureau of Reclamation does not waste any of the water’s potential because they consider it a valuable resource,” explained Jorgenson. “They prefer all the water go to these generators.”
When the dam was initially built, its primary purpose was to help with water storage. As Los Angeles started growing, the L.A. Power Plant began utilizing the dam for power generation purposes. Hendrix indicated that the power is very coveted on the spot market, and especially in the western part of the country, because if there is an immediate and instant need for power there, they can provide it.
Today, power that is generated in the dam is turned over to the Department of Energy, the Western Area Power Administration. The administration markets and sells all of the power that the dam makes and provides the dam with a percentage of the sale. The money the dam receives from the Department of Energy is then used to help with the upkeep of the facility. Anytime repairs warrant a change of part, the maintenance facility makes sure that they are putting in the most modern and technologically advanced parts. As a result of its continued technology updates, the dam has been able to generate an immense amount of energy while increasing its efficiency.
Favorite Part of the Job — Teaching and Mentorship
Speaking of the how the dam is operated, Hendrix recognized the caliber of talent possessed by the engineers and journeymen working in the facilities. “Through our apprenticeship program we hire people who are very highly trained in specialty welding, metals or related disciplines. Less and less people now go into these types of trades”, commented Hendrix. “A lot of candidates come here from the Army Corps of Engineers, Public Works or military, things that are immediately transferable. We train people to be millwrights, welders, machinists, pipefitters which is invaluable experience for them.”
The dam offers several extensive four-year apprenticeship programs. From those, mechanical and electrical apprentices are the ones who work with Jorgenson’s team. “It is a pretty tough program because they have to spend a lot of time doing that, they pretty much have given up their lives for four years,” he said. The meticulous program teaches the apprentices a lot of different disciplines and provides hands-on experience with several applications and processes.
Without missing a beat, Jorgenson said teaching is his favorite part of his job. He believes it is very important to train and mentor new engineers; when one of his new students is successful it is incredibly rewarding. Why? “Because as a foreman, I get to teach my guys new ways to weld and I enjoy the heck out of that.”