Building bridges: CD5 creates construction jobs: ConocoPhillips to use low-impact construction technique.

• Author: West, Gail
• Position: SPECIAL SECTION: Building Alaska

ConocoPhillips is moving forward with construction of the billion-dollar Colville Delta 5 (CD5) project, a new Alpine drill site on the eastern edge of the National Petroleum Reserve-Alaska (NPR-A). The project will consist of a gravel road and pad along with affiliated drill-site facilities, pipelines, four bridges, and fifteen wells--with space for up to eighteen additional wells, according to the company.

Through its contractors, ConocoPhillips will begin building these four bridges--ranging from about 200 feet to 1,400 feet--along a 6.2-mile-long road from Alpine to the CD5 site. The project will create approximately five hundred new construction jobs during the next several construction seasons.

The four bridges will carry both traffic and oil and gas pipelines, according to James Brodie, ConocoPhillips' capital projects manager for CD5 and NPR-A. Although the Alpine Field is not connected to the North Slope road system, Brodies says, year-round access between the main Alpine pad and CD5 is critical to safe and environmentally sound operations. All bridges should be complete by May 2015.

PCL Construction, in conjunction with CH2M Hill and Ruskin Construction Ltd., will be building two of the four bridges, including the 1,400-foot bridge, and Nanuq Inc./Alaska Frontier Constructors as a joint venture will build the remaining two bridges.

Unique Technique

The three shorter bridges "are more typical of what we do," Brodie says. These three will provide additional flow capacity (compared to culverts) in case of high water during breakup. The smaller bridges cross a dry lake bed, what Brodie calls "a paleochannel," a remnant of the Colville that is now inactive, and the Nigliagvik Channel of the Colville River.

The longest of the bridges, which crosses the Nigliq Channel, will consist of steel pilings, seven midstream pier groups with sheet-pile abutment, and a steel box superstructure. "It will have eight spans of concrete deck panel ranging from 175 to 200 feet each and will be the longest bridge on the North Slope," Brodie says.

One of the construction techniques ConocoPhillips anticipates employing for this bridge is relatively unique, Brodie adds: "We'll use a launch structure that we build on the gravel at one end of the bridge, then we'll push the bridge out span by span across the channel." He says it's the optimal technique to reduce the amount of heavy equipment on environmentally sensitive areas. "It's definitely a lower impact...