Underground construction projects today are more complex than they once were, and utility contractors must be proficient in several disciplines to compete for the turnkey contracts that many project owners prefer.

Work must be done correctly and in accordance with specifications, even under difficult conditions when working against tight completion deadlines.

A recent fiber-optic project completed in Phoenix, Arizona by Speedy Gonzalez Construction, Inc. (SGC) is a good example. SGC was the primary contractor for construction of a 38-mile-long segment of AGL Networks' Deer Valley North Loop. Based in Atlanta, AGL Networks constructs, owns, and manages underground fiber-optic networks that unite telecommunication service providers and their business customers.

The Deer Valley North Loop project is a part of AGL Networks' 60-mile Phoenix network that circles primary commercial areas of Phoenix and Tempe, providing accessibility to the main COs, IXCs, and carrier hotels. The network has new premium enhanced fiber available for custom configuration to customer-specified destinations.

Gonzalez crews installed two 1-1/4-inch HDPE conduits and placed one cable with 144 fiber strands and one with 288 fiber count in the duct. The project also included (165) 3x5 foot pull boxes, (40) 4x4 concrete vaults, and restoration of all paved and landscaped surfaces that were disturbed during construction.

The project was broken into eight segments, said Salvador Gonzalez, owner of the company that bears his name.

The cable route passed through both residential and business areas and included four Arizona Department of Highway crossings, 54 crossings of major city streets, four canal crossings, and crossing under four flood control channels.

Because of site conditions, 98 percent of the conduit placement was completed by horizontal directional drilling (HDD).

Directional drilling was the best, most cost efficient method for making street, highway, and canal crossings, and greatly limited surface damage throughout other segments of the project, says Luis De La Cruz, SGC manager.

Drilling was completed with four Ditch Witch® HDD units: a JT1720, two JT2720 units, and a JT4020.

Powered by an 85-horsepower diesel engine, the JT1720 develops 17,000 pounds of pullback, 1800 foot-pounds of torque, and spindle speeds to 200 rpm. The on-board fluid system can pump 25 gpm of drilling fluid.

The JT2720's 125-horsepower turbocharged diesel engine and powerful hydraulics develop 27,000 pounds of pullback, 3200 foot-pounds of torque, and spindle speeds to 225 rpm.

The 40,000-pound-pullback JT4020 develops 5000 foot-pounds of spindle torque, and spindle speeds to 250 rpm. While still relatively compact, the model has plenty of power to pull in much larger conduit than was used on the North Loop project.

All three models are self-contained directional drilling systems mounted on rubber tracks. Built-in pipe racks hold enough drill pipe to complete most jobs, and automatic pipe makeup and breakout and pipe thread lubrication allow the operator to add or remove drill pipe without assistance from another crew member. Hydraulic leveling and anchoring speed set up. All use Ditch Witch Electronics guidance equipment manufactured by The Charles Machine Works, Inc., the same company that makes the Ditch Witch drilling equipment.

The project required 385 bores ranging in length from 150 to 600 feet. Soil conditions ranged from ideal to wash cobble of various sizes. De La Cruz said all bores were drilled with standard slant-face Ditch Witch bits. Pilot holes did not require use of a reamer for enlargement for pulling in the small-diameter conduit.

When crossing or working close to existing buried utilities, pipe and cable was physically exposed to confirm its exact location before work proceeded. For potholing, SGC employed three FX30 Ditch Witch vacuum excavation units. Using high-pressure water, these "soft" excavation tools quickly make small potholes to uncover buried facilities. The units' vacuum capabilities were used to keep work sites clear of drilling fluids.

The project was completed in 115 work days that included six-day work weeks.

"We worked nights only in areas where daytime construction would hinder community activities," said De La Cruz. "Most work around shopping centers, schools, and restaurants was done at night."

Planning, permitting, and coordination with various government agencies and other organizations was a complex task.

"At one time or another, we interfaced with 14 different agencies," said De La Cruz. "Because the work was in urban areas, traffic control had to be implemented which required submission of control plans and their approval before work could proceed. And the job isn't finished until each site has been completely restored."