Air and Water: The Elements of Productivity

New technology arises from a need to make life easier, safer, less expensive, more productive — generally better in some way. But sometimes old technology, applied in a new way, can do the same thing.

This is the case with vacuum excavation systems, which have been around since the 1950s, but only in recent years have their many capabilities begun to be realized. These versatile units — also called vacuum excavators, vac systems or simply “vacs”— are used by an increasing number of industries and municipalities for cleaning spills, storm systems and gutters; “soft” excavation tasks such as potholing and utility locating; preparing roads for repaving; and other public works tasks.

Versatility is a vac system’s main attraction, but there are numerous other benefits. For one, they are much easier on the environment, particularly around utility construction sites, where damage prevention is of critical importance. A vac system, properly used, is one of the easiest and most effective ways to locate utilities.

Simplifying Utility Location

With each underground construction job, a thorough damage-prevention routine is necessary for minimizing the possibility of utility damage. The addition of a vacuum excavation system can make the process even more thorough.

One essential part of the damage-prevention program is accurately locating and marking all utilities in a work area before construction. Contact your local one-call center — or dial the new national 811 number, if available in your part of the country — to request that locates be made at the work site at least 48 hours before work is scheduled to begin. The one-call center will contact the appropriate utility providers, who then locate and mark approximate positions of their buried lines.

Because of accelerated efforts to prevent damage to buried utilities, a standard practice on a growing number of utility jobs is called “potholing” or “daylighting,” i.e., physically uncovering the buried utility to determine its exact location. Government agencies are adopting regulations that require potholing, but many project owners and contractors already understand the importance of potholing at horizontal directional drilling (HDD) or other construction sites when the path of a planned pilot bore either crosses or is in proximity to buried lines.

Vacuum excavating is faster, less labor intensive and results in a smaller hole that is less expensive to refill and/or patch.

This is why vacuum excavators are fast becoming the equipment of choice for potholing. With a portable vacuum excavator, soil is displaced by a controlled stream of water directed by a hand-held wand and removed by suction. Water for excavation is discharged from the unit’s supply tank; the unit’s vacuum component picks up soil displaced during excavation and stores it in a holding tank to use later as fill or to be removed from the job site. (It is important that contractors know their state’s requirements for proper spoils disposal before beginning a project.) Depending on soil conditions, a 12-in. square, 5-ft deep pothole can be completed in less than 30 minutes. Vacuum excavators can dig much deeper, but utility potholes seldom need to be more than 6 ft deep.

Vac systems are also ideal for use during HDD operations, particularly for vacuuming up drilling fluids that escape from pilot holes during drilling and backreaming. Although most drilling-fluid additives are not harmful to the environment, project owners and municipalities usually require that work areas be kept free of the drilling fluids and disposed off site; compact, maneuverable vacuum excavators can do the job faster and more efficiently than any other equipment.

Operator Benefits of Vac Systems

Vacuum excavators are designed to minimize damage to not only the utilities but also easy on the operator. As opposed to some mechanical equipment, vac systems are quieter and produce little or no vibration, which minimizes operator fatigue — and a jobsite with buried utilities is one place where every worker needs to be as alert.

Vacuum excavators are also relatively easy to use, requiring only one operator. The lightweight, compact Ditch Witch FX30, for example, is easy to transport — no CDL necessary — and easy to maneuver around the site. The operator doesn’t have to position the unit right in the middle of the jobsite because, like many vacuum excavators, the FX30 has 50 feet of hose that can be snaked into areas that would be impossible for large construction equipment to reach. And in congested urban areas, the unit can be positioned so that it doesn’t interfere with traffic flow.

Finding Common Ground

The innovative use of equipment such as vacuum excavators is only one strategy in preventing utility damage. Utility damage prevention is a responsibility that involves many diverse public and private organizations, making communication and cooperation essential to reduce the number of underground utility strikes.

Common Ground Alliance (CGA), a private, non-profit organization that is dedicated to coordinating information and communications among the various organizations involved in building, maintaining and operating the utility infrastructure. Among CGA’s many responsibilities is the development of a national campaign to promote the awareness of 811, the national call-before-you-dig telephone number that will eventually interface with all of the nation’s 71 one-call centers. The number is currently active in some locations and is expected to be available nationwide by mid-2007.

Another responsibility of CGA is to implement best-practice procedures identified in its Common Ground Best Practices Study, a landmark study that is recognized as the most effective set of guidelines ever developed for preventing damage to underground facilities. Information about CGA programs is available on the CGA website:

Jason Proctor is product manager-vacuum excavation at Ditch Witch.

Choosing the Right Vac System for You

A wide range of vacuum excavator models are available. To find the model that best suits your application, compare the following features:

  • Horsepower and torque curve of the power unit
  • Type of positive displacement pump or blower used to create vacuum
  • Capacity of pump or blower (in cubic feet per minute, or cfm)
  • Speed and filtration of air flow through the system
  • Pressure and gallons-per-minute (gpm) of water pump  
  • Nozzle configuration of the excavation tool
  • Size and weight of the unit when empty
  • Weight of the unit when holding tank is full
  • Capacity of the vacuum holding tank
  • Capacity of the water supply tank on water models or dust-filtering systems on air units
  • Sound level during operation

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