Versatile, multi-purpose vacuum excavators are standard equipment on most horizontal directional drilling (HDD) project sites.

A compact, mobile vacuum excavation system—mounted on a trailer or truck bed—uses high-pressure water or air to make precisely controlled excavations to visibly expose already-buried pipe and cable. As excavation proceeds, the unit's vacuum removes spoil to a self-contained storage tank for reuse as fill or removal from the site.

Depending on soil conditions, a 12-inch-square "pothole" six feet deep can be completed in 20 minutes or less. Perhaps most important, a vacuum excavator's "soft" excavation technology reduces the risk of damage inherent with mechanical excavation methods such as backhoes, excavators, and shovels.

During drilling operations, backreaming and product pullback, the machine's powerful vacuum keeps the work site free of drilling fluids that flow from the bore hole.

However, the vacuum excavator's usefulness is not limited to HDD projects.

Anywhere buried utilities are present and excavation of any kind must be performed, potholing is advised and, in some areas, mandated. The vacuum excavator is recognized as the fastest, most efficient way to expose utility lines with the least risk of damaging them during the process.

In addition, it did not take construction personnel long to recognize that soft excavation often is the best way to make small excavations for just about any purpose and to use the equipment for general cleanup and many specialized applications.

Titan Communications, Inc., Albuquerque, New Mexico, is a utility contractor specializing in telecommunications, electrical power and gas projects. Titan crews use two Ditch Witch FX30s and one larger FX60 vacuum excavator for the standard HDD applications of potholing and directional drilling fluid cleanup.

"Potholing is definitely a necessity these days," says Travis Mills, Titan treasurer. "And the state prohibits mechanical excavation over utility markers, so without a vacuum excavator it would mean digging by hand, and some of the potholes we do are five, six, and seven feet deep. Vacuum excavation is faster and it's much safer. We want everyone to go home at the end of every workday."

The Hillview Water Co. is a private company providing water services to Oakhurst, California, a city of 18,000 located 12 miles from the southern entrance of Yosemite National Park.

The company uses an FX30 vacuum excavator for accessing pipe to repair leaks and to make excavations to connect new services and to make spot repairs on existing water service lines, says Roger Forrester, Hillview Water president.

"Acquisition of this machine has been very advantageous for us," Forrester continues. "The machine makes a nice, clean hole, rather than the larger excavations made by backhoes and excavators, limiting damage to surrounding areas and reducing the amount of surface repairs required after a repair is made. This method of excavation also reduces the chance of damaging our pipes when we uncover them or causing damage to other nearby utilities that are in the ground."

PARC Environmental, Fresno, California, offers a wide range of environmental remediation and cleanup services and uses an FX60 model vacuum excavator for recovery and removal of various types of materials. The self-contained vacuum excavation system is mounted on a truck that also transports tools and other equipment.

"Typical projects where the machine is used are cleanup after demolition of structures and for site preparation," says Louie Martina, vice president of operations for PARC. "We first rented a machine and then purchased it about nine months ago. It serves our needs very well."

The City of Riverbank, located along the banks of the Stanislaus River in the heart of California's Central Valley, uses a model FX60 vacuum excavator for making a variety of repairs to its water system.

"We use the vacuum excavator to excavate around mainline leaks so repairs can be made," says Eric Tackett, the city's domestic water supervisor. "Because the machine digs with water, we can reach leaking areas without the risk of causing more damage during excavation. The machine also lets us dig around other buried utilities without risk of damaging them."

As the excavation is made, spoil and water and mud caused by the leak are vacuumed up.

"Before we got the machine, all that was pumped out onto the street, making a big mess which sometimes could enter storm drains," Tackett adds. "With the damage exposed, the vacuum excavator also can clean out pipe around a break removing mud, pieces of broken pipe, and other debris. This helps prevent contamination from entering the damaged pipe, and that is very important."

The machine also is used to access breaks in service lines leading to homes and buildings, minimizing damage to lawns. Spoil and mud from breaks is stored in the FX60's debris tank for later disposal. Clean, dry fill is used to restore excavations.

The two Ditch Witch vacuum excavator models are well suited for conventional support of HDD operations and many special applications.

The FX30 is powered by a 26-horsepower diesel engine, and its blower develops 500 cfm and up to 15 inches of mercury, providing powerful suction force. Maximum water pressure can be controlled in increments to a maximum output of 3000 psi for excavating. It is available with a 500- or 800-galllon debris tank and a 80-, 200- or 300-gallon supply tank to supply water for excavating.

The larger FX60 is powered by a 60-horsepower, liquid-cooled diesel engine. For vacuuming, the machine's belt-driven blower develops maximum airflow of 900 cfm and up to 16 inches of mercury. For excavating, soil is displaced by water at pressures of up to 3500 psi. The FX60 can be equipped with a 500-, 800- or 1200-gallon debris tank. Water-supply tanks are available in 80-, 200- or 300-gallon sizes.

Both models are available as a trailer-mounted package or on skids for mounting on trucks.

Ditch Witch equipment is manufactured by The Charles Machine Works, Inc., Perry, Oklahoma. In addition to vacuum excavators, horizontal directional drills and support equipment, the Ditch Witch product line includes electronic HDD tracking systems, trenchers, vibratory plows, compact utility equipment and electronic utility locators. Ditch Witch products are sold and supported by the worldwide Ditch Witch dealer network. For more information, call 800-654-6481 or visit ditchwitch.com.