Vacuum Excavation – Water or Air Powered

A fresh look at air excavation systems leads to equipment that will meet future market needs.

It is safe to say that everyone in the business of excavating around underground utility infrastructure is aware that both wet and dry vacuum excavation systems have been satisfying the needs of the “soft excavation ” process for many decades . It may also be evident to an attentive market observer that the type of systems available today will not
have the ability to meet the developing requirements of this fast -growing industry .

The need for vacuum excavation projects has exploded in recent years due to increased demand for more reliable underground electrical distribution systems, faster and more efficient telecommunications systems and the additional demand resulting from legislative requirements established by governmental agencies or interstate initiatives like 811.

The earliest requirements for vacuum excavation applications were fulfilled by using either rudimentary air excavation systems or by commissioning sewer cleaning rigs that were modified to be used as hydro-excavation trucks. Gas, electric and telecommunications utility companies and their contractors performed maintenance and repair tasks on utility distribution systems using simple air excavation trucks fitted with an air compressor, a basic air filter and a vacuum producer to gain access to utilities that were two to five feet below the streets. “Water jetting” trucks that were originally designed to clean the inside of sewers and storm drains were used to gain access to the outside of damaged or leaking underground lines by adding a handheld water wand to liquefy the soil that covered these utilities. As with any new technology, the leaders of each excavation method began to develop a vision for their preferred equipment configuration by implementing modifications to their existing product offerings.

Over time, the hydro-excavation method gained traction in the marketplace. The hydro-excavation approach was presented as a fully-developed technology while air excavation
equipment was said to exhibit a need for more development before it could be considered a viable production process. Early air systems were slower at digging in some soil conditions and required more sophisticated filtration equipment to keep them running at a suitable level of performance. Manufacturers of hydro-excavation systems were able to build a business case for the excavation contractor in which they could justify the cost of these very expensive systems if these contractors could capture enough work to keep their machines busy and the revenue flowing. Prior to the existence of the Common Ground Alliance (CGA), the users of these early hydro-excavation systems could capture entire regional markets by merely beating the price of a competitor that was hand digging or struggling to dig cautiously in these sensitive excavation zones using hard excavation machines.

Currently, when experienced manufacturers engage in the design of a product it is good
business practice to implement a “design review” process. Consider manufacturers of products such as commercial aircraft or pharmaceutical products. Consumers of pharmaceuticals or the flying public are reluctant to use these products if they have not been qualified by a rigorous review  process. People prefer air travel because it is fast and inexpensive, but there would be considerably fewer air travelers if they thought that the airplane manufacturers had not performed an extensive design review process to make all airplanes as safe and reliable
as they are today.

Based on the hydro-excavation excavation process established by systems available today,
it is unlikely that early system manufacturers subjected their operating paradigm to a
rigorous design review process. Why would any mature market participant take the short- term risk of exposing their customers to an excavation process that would require thousands of pounds of water to be transported to the excavation site and then, after performing the excavation process, be hauled away in the form of mud? It is also unlikely that system designers would have supported a process that demands that the excavated soil be replaced with dry soil that must be transported back to the excavation for site restoration. A rigorous design review process would have also identified that customers who purchase this equipment would be reluctant to embrace an excavation process that regularly demands interruption of the process to transport the excavated material to a dump site or to refill their water tanks. It is also safe to assume that an extensive design review process would have also identified the environmental concerns created by the fact that water is a precious resource in some locations, which may add significant cost and complication to the process, and that the injection of water into some contaminated soils may release contaminants from the soil and into the local water table by spreading a “plume” of contaminated water.

There are a couple of air system manufacturers that have been designing and manufacturing vacuum excavation systems for many years. Understanding the need for both the water and air excavation methods, a sophisticated hydrophobic (water repellant) filtration system that could operate wet or dry without a need to reconfigure the pneumatic flow of the system was designed and implemented. Extensive design reviews were executed that determined that the system would not exclude, but would minimize, the use of hydro-excavation. This decision to excavate using air or water would be based on actual soil conditions, leaving the excavating technique and quantity of water to be used to the discretion of the system operator. Since the design review process resulted in focusing the design effort toward the air excavation process, it was also determined that the filtration system must clean itself constantly during the excavation process to insure peak performance 100% of the time the equipment is operating.

These design reviews did not end with a determination of the most desirable excavation method. Extensive lists of requirements that were important to their customers were collected to better understand how their systems could best meet their needs. Attributes such as size, weight and cost were high on the list. It was clear that customers would prefer the smallest, lightest and least expensive system that could do the job economically and effectively. Just like early cell phones, customers were not fully satisfied with a device that was the size and weight of a brick. Effective air powered vacuum excavation systems that can excavate a 12”diameter by five-foot deep hole in less than seven minutes are now light enough to be mounted on a four-wheel drive class five (F-550) chassis, and can be  delivered at prices that are less than half the price of an analogous hydro-excavation system.

This decision to excavate using air or water would be based on actual soil conditions leaving the excavating technique and quantity of water to be used to the discretion of the system operator”

Today’s business environment demands that manufacturers work with their customers to understand what they want to do with their product and then deliver that exact product. These actions should result in completing a “value proposition” with the customer. The most important thing a supplier can do is understand how their customer wants to use their product and then provide that solution. If any manufacturer expects to deliver a credible value proposition it is imperative that they perform an extensive design review process that takes a fresh and thorough look at each customer’s real needs and follows this review with a well-designed product with the ability to satisfy those needs.


Frank Russo is vice-president of Tellus Underground Technology, Inc. He can be reached at frusso@tellusunderground.com.

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