Mountainous Infrastructure Project Takes Shape

Design-Build In New Mexico
May 2011, Vol. 66 No. 5

Trenchers vs. volcanic rock
Road projects consisted of grading and preparation of the road bed, shaping of drainage features and installation of base course and culverts. The water system required the installation of six-inch, C-900 PVC lines, including valves, fire hydrants, stubouts, pumps and water tanks. Sanitary sewer lines also called for the use of PVC material installation (eight-inch, SDR 35) and placing of precast HDPE manholes, stubouts and lift stations. Electrical lines were run through three-inch conduit and telephone lines through two- and four-inch PVC. All new development was tied into the village’s existing infrastructure.

Throughout the trenching process, AUI equipment operators learned to adapt to various soil conditions, which ranged from volcanic rock to clay. The crew, which was composed of approximately 80 employees, ran 11 excavators, two trenchers and seven loaders, as well as various other pieces of equipment to support the large machines. Equipping the excavators with breakers helped operators power through the stubborn rock.

Trenchers were called in to excavate the miles of water, sewer and utility lines -- each requiring trenches of varying depths. Water lines required seven-foot trenches; SAS called for trenches anywhere from 8.5 to 16 feet deep; electrical and telephone lines needed three and four-foot deep trenches respectively.

AUI chose two Vermeer trenchers -- models T1055 Commander 3 and T955 Commander 3 -- for the project, citing cost and the depth and width of the cuts necessary as the two main reasons for the equipment selection.

The track trenchers are among the largest available in the market. They are designed specifically to excavate among tough soil conditions, which made them ideal machines for the Angel Fire terrain. According to the manufacturer, the trenchers’ ability to break through the most difficult of surfaces is due to splined headshaft motors that offer low speed and high torque.

“AUI has been working with Vermeer on track trencher technology for years and figured the Angel Fire project could benefit from the use of trenchers,” said Vickers.

Vickers reports that AUI was able to install water lines in Angel Fire at anywhere from 300 to 800 feet per day, per crew and sewer lines at 120 to 220 feet per day, per crew. The high efficiency of the trenchers, which boast high-volume spoil removal with an extra-wide conveyor opening, aided in the crew’s speed.