As part of the larger Canoa Ranch Rest Area Rehabilitation project, ADOT tasked Premier with preparing construction documents for two miles of new ductile iron water transmission main (6- to 12-inch) along the I-19 Frontage Road. This waterline allowed ADOT to abandon the aging onsite groundwater well and booster station and connect to the more reliable Green Valley Water District (GVWD) public water system. Premier worked with GVWD’s consultant to determine the pipe sizing necessary to deliver the required flow and pressure to the rest area.
The proposed waterline alignment crossed several natural washes, corrugated metal pipe (CMP), and reinforced concrete box culverts (RCBC). Rather than using a more expensive jack & bore type installation, ADOT and GVWD chose to reroute the waterline around the larger RCBCs and tunnel under the smaller CMP culverts, which eliminated almost 540 feet of jack and bore construction and created an estimated savings of $1.5 million.
Due to the rocky nature of the surrounding terrain a geophysical, seismic refraction, we performed survey along the proposed alignment to provide a clear picture of the subsurface, which helped determine if special excavation methods would be required to install the new waterline.
Significant coordination with ADOT and GVWD was needed to resolve conflicting design and construction requirements as well as maintenance access and ownership agreements. Permits for construction were obtained from GVWD, ADOT, and Pima County.