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What is Hydrovac Excavation

The United States has been able to liberate more natural gas and oil from the ground than ever before.  They’re doing this with the help of a technique known as hydrovac excavation (also known as hydro excavation).  In fact, according to the Independent Petroleum Association of America, 90% of all wells in the United States were built using hydrovac excavation technology.

But what is hydrovac excavation?  Hydrovac excavation is the process of using highly pressurized water to dig underground.  It can be used to dig down vertically as well as horizontally and it works more efficiently than more traditional methods of excavating.

In fact, there are situations where hydro excavation is the only viable method for excavating an area.  Without the use of this technology, excavation would not be possible for this area and operations would have to be completed elsewhere.

How is Hydrovac Excavation Used

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Precision Hydrovac Excavation Hole, Image by Ryan, CC BY 2.0

Over the last decade, natural gas mining companies have used this technique to create another energy boom here that has created many jobs and brought down energy costs throughout the country.  Armed with this method of drilling, the American Geosciences Institute estimates that the industry could recover over 2,462 trillion cubic feet of dry natural gas.  At current consumption levels and export levels, this would give the country another 90 years of natural gas.

However, this isn’t the only way the oil and gas industry can take advantage of hydrovac excavation.  They can also use it to help them run, repair, and maintain their vast networks of pipelines.  In midstream pipeline operations, hydro excavation is often done to complete non-destructive repairs and modifications.

For example, a company may decide they need to uncover a section of a pipeline that is buried eight feet underground.  Traditionally, they would have to use a crew to dig down eight feet.  During this process, they’d risk damaging the pipeline with their equipment and crews would risk falling victim to trench cave-ins.

With hydrovac excavation, the company does not have to worry about these issues.  They can use pressurized water to dig the hole without damaging the pipe and large vacuuming equipment to collect the pressurized water as the digging commences.  This process ends up being safer and much faster than digging the pipe up using more traditional means.

This is especially useful during potential leaks as the quicker the excavation takes place, the quicker the leak can be contained.  This results in less damage to the environment and a smaller amount of lost product.  It also results in shorter disruption times which can be detrimental to the pipeline and the people who rely on its product.

Also, in areas with permafrost, hydro excavation may be the only way to dig a hole.  The reason it is so effective in these conditions is that it can make use of hot water which helps to penetrate the permafrost where traditional digging equipment would not be as effective.

How Does Hydrovac Excavation Work

Hydrovac excavation uses highly pressurized water to turn the solid ground into mud.  These pressures can range from 10,000 PSI up to 55,000 PSI depending on the application.  Higher pressures make it possible to quickly bore through harder ground.  However,  high pressure should only be used when necessary as they do carry a higher risk to the pipelines that they are being used to uncover.

For this reason, pressure hoses are usually color-coded to show operators and inspectors at a glance, which pressures are being used and where.  These color schemes are used to quickly identify the pressures being used:

Pressure Color Code
10,000 PSI Yellow
15,000 PSI Green
20,000 PSI Blue
30,000 PSI Silver
40,000 PSI Orange
55,000 PSI Red

 

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Hydrovac Excavation Vacuum, Image by Ditch Witch, CC BY 2.0

While these high-pressure hoses create mud, this mud is simultaneously vacuumed up into a vacuum truck or trailer and a hole is born.  The vacuums typically use a fan system which helps them vacuum up the soil at incredible speeds which results in much quicker excavations.  This dirt can sometimes be put back into the ground afterward, but will often be taken off-site and used for other purposes.

Hydrovac Excavation Equipment

Hydrovac excavation usually requires fewer pieces of equipment as well as fewer workers to complete.  Instead of heavy machinery and drills, all a hydro excavation team needs is a hose, a vacuum and either a hydrovac excavation truck or trailer.  Trucks and trailers will range in size and larger excavations will usually make use of larger trucks while smaller excavations can complete their projects with smaller trucks and trailer-mounted hydro excavators.

A hydrovac excavation crew can consist of as few as three people.  One person will be at the truck while another person works the hose and another crew member operates the vacuum.  Many newer trucks require even fewer workers.  In fact, computer-controlled trucks might only need one operator.

With a computer-controlled truck, the operator can do all of the steps needed by himself.  He’ll drive the truck to the location, set up the computer, and then use a remote to bring the vacuum boom into position.  Next, he’ll set up the hose and begin the excavation.  If he needs to readjust the vacuum, he can do so with his remote.  Additionally, he’ll have a remote emergency shut-off switch so all operations can be halted at a moment’s notice.

Hydrovac Excavation Benefits

The main benefit of hydrovac excavation is its ability to quickly and safely dig holes in a non-destructive manner.  It can create a hole leading down to piping and utility lines without harming the pipes and lines in the process.  This reduces the number of power outages, sewage leaks, gas leaks, and even telecommunication outages that can be caused by improper destructive digging.

Another benefit of hydro excavation is its ability to dig through permafrost and other difficult conditions that traditional excavating equipment might not be able to break through.  The Canadian oil and gas industry started using this technology decades ago for this very reason.  Without hot water hydrovac excavation technology, they may not have been able to carry out year-round operations in many locations throughout the country.

Hydro excavation also has environmental benefits as well.  This is because it uses less machinery than traditional digging which leads to less soil compaction.  A single truck may be all that is needed to daylight a pipe where previously multiple pieces of large digging equipment may have had to have been brought on site.

On top of all of this, hydrovac excavation has economic benefits as well.  The number of crew members needed to complete a hydro excavation is far fewer than the number needed to complete more traditional excavation projects.  Also, projects can be completed faster so there are fewer disruptions to operations and more projects completed within shorter timeframes.

Hydrovac excavation results in lower restoration costs as well.  This is because the area around the excavation site is less disrupted so there aren’t as many areas that need to be restored after a hydro excavation.

Hydrovac Excavation Safety

Hydrovac excavation is a safer alternative to traditional methods of excavation.  One of the reasons for this is that it is more precise.  A hydro excavation team can quickly dig a hole within the exact parameters that they need to complete the job.  With other methods, they may have to dig a large trench which can put workers at risk of falls and cave-ins.

Because of hydrovac excavation’s great precision, it can safely avoid utility disruptions which can often be catastrophic to the surrounding areas.  For example, one large utility disruption can lead to a multitude of accidents throughout the area.  Even the avoidance of water lines can protect residents against flooding and all of the dangers that come with it.

Final Thoughts

When compared to traditional excavation techniques, hydro excavation is a much safer and more efficient excavation method.  The technology has already lead to many great advancements in the pipeline industry as well as many other industries and will only continue to do so in the future.

Hanging H offers an array of gas distribution services, including hydrovac excavation.

If you enjoyed learning about hydro excavation, why not check out our article on horizontal directional drilling.

October 4, 2019

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