Also complicating the excavation was an AT&T transcontinental fiber-optic line that had to be lowered prior to the bypass construction. In order to work within the RID annual dry-up period, the AT&T fiber-optic line and bypass wyes for the canal were constructed prior to the start of the main project, Slagell says.

prison factor

The close proximity of the ">Perryville women's prison—which is expected to house Arizona inmate Jodi Arias later this summer—caused design changes and brought unique challenges to the construction team. In order to limit sight-line encumbrances in case of a jailbreak, retention basins were specially designed. Construction crews also had to go through security clearance before entering prison grounds.

"The surveyors and their equipment had to be cleared a week before entering the prison," Slagell said. "During design, the slopes of the basin next to the prison were limited to a run-to-rise ratio of 6 to 1 so as to provide visual access to the basin."

Certain portions of a farming facility tied to the prison also had to be altered in the northwest quadrant of the interchange site.

"Duncan Family Farms has a special-use permit from the Arizona Department of Corrections, which in turn has a lease with the Arizona State Land Department," Baird says. "Engineered organic compost was located on the northwest corner of McDowell Road and Cotton Lane, which conflicted with the relocated Cotton Lane ramp construction and Loop 303. The compost operations had to be removed and relocated prior to the start of construction."