January 2021 Vol. 76 No. 1


Things to Consider When Buying a Vacuum Excavator

By Jeff Griffin, Senior Editor

The vacuum excavator is a dual-purpose machine that has become an important addition to many underground construction equipment fleets over the past few decades. 

Most equipment used for underground utility construction (with the exceptions of loader-backhoe, compact excavator and compact loader) are considered specialty equipment, such as trenchers and directional drilling rigs, which have specific purposes. 

For utility construction, vacuum excavators have two primary uses: removing drilling fluid from job sites and potholing to visibly confirm locations of existing utilities. However, they have multiple other uses that can help justify ownership: general cleanup, excavating utility and sign pole holes, digging trenches in areas impossible to access with conventional excavation equipment, and numerous other tasks. 

When considering investing in vacuum excavation equipment, prospective buyers need to seek answers for several questions: 

  • What task or tasks will the equipment be expected to perform?
  • How much excavating and vacuum power will be needed?
  • Is method of excavation (air or water) a consideration? If yes, what are factors to consider?
  • Is physical size and weight of equipment factors?
  • Will equipment be mounted on a trailer or truck chassis?
  • Is there a brand preference?
  • How important is access to parts and service?
  • Is training available from the manufacturer or dealer? If yes, is job-site training offered?


Determining needs 

Factors under consideration can vary in importance for a small company needing one machine versus large organizations operating multiple machines. Users may be utility contractors, utility service provides or specialty contractors who do potholing and site cleanup. 

A primary benefit of a vacuum excavator is its ability to make precisely controlled holes or excavations by “soft” excavation which, for potholing, greatly reduces the risk of damage to the utility being exposed or others in the immediate area. Common Ground Alliance Best Practices say vacuum excavation is the safest method of potholing, eliminating the risks of damage from mechanical methods such as a backhoe, compact excavator or shovel. 

Most vacuum excavators for utility applications use water (hydroexcavation), but thoughtful buyers should investigate  
air models, as well. There are pros and cons to each technology (see sidebar). 

Buyers have several sources for vacuum excavation equipment and Tony Bokhoven, director of sales for Ring-O-Matic, explained how to evaluate them. 

“Air excavation is not as universal as digging with high-pressure water,” Bokhoven said. “I think contractors don’t spend much time considering it unless the ground conditions are such that lend themselves to air versus water.” 

Bokhoven added there are areas of the market for vacuum excavations that can still be developed. 

“I believe there are portions of the market that are well-versed in how vac ex and the soft dig process is beneficial to the overall success of a job and the safety it provides for HDD installation,” he explained. “But I also believe that the municipal side of the industry is still learning the benefits and advantages that  
vac ex can provide to them.” 



As with all types of equipment, there are potential safety risks. Operator manuals of every model include detailed safety warnings. 

Hydroexcavation safety is more than just addressing the use of the machine,” said Bokhoven. “We teach about what to do under the surface, as much as we train the process of digging. There are numerous things a contractor should know when it comes to soft digging and how to prevent damage, and also how to transfer what they learn underground to the drill operator and mud mixer.” 

Static electricity is a risk that inexperienced users might overlook. 

“Static electric combustion should always be a concern when vacuuming dry material, not just in digging,” he added. “These units are often used to vac up dry material and not introducing water always is a concern. Operators always need to be aware of vapors and combustible liquids.” 

As previously noted, the versatility of vacuum excavators adds value to any equipment fleet. They are all-purpose cleanup tools on job sites and equipment yards, and many users discover unusual jobs they can perform. 

“New uses and applications arise every day,” said Bokhoven. “Utility construction is a continually growing and changing industry, and vacuum excavators will become more and more important as more utilities go below ground and as more fluids need capturing.” 

The Ring-O-Matic vacuum excavator line ranges from a 150-gallon unit up to a 3,000-gallon truck-mount model. 


Ring-O-Matic Manufacturing Co., (641) 628-1515, ring-o-matic.com 


Water or Air? 

Most vacuum excavators on utility worksites are hydro-based, but the advantages and benefits of air equipment should not be overlooked. 

Excavators with high-pressure water penetrates most types of soil, but they require a supply of water to dig, which can be an inconvenience and added expense when water supplies are not near the job site. 

Improperly used, hydro-excavation can cut cable or plastic pipe, damaging the facilities that are being located to, in order to protect them from accidental damage. Muddy spoil from digging has to be removed. 

Excavation with air requires no water supply and produces no wet spoil. High-pressure air will not damage utilities. However, air excavators are not effective in all types of soils. 

Many air models now have a hydroexcavation backup, and some water equipment today also has an air option. 

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