Past Performance - Heavy Civil

Project Description

This project, located in Nogales, Arizona, consisted of diverting the Nogales wash to allow for the construction of a new channel complete with bank protection and a new bridge spanning the Nogales Wash. Water was diverted from the upstream side of the project and released at the project limit on the downstream side through the use of 3-8 inch pumps and 1,000 feet HDPE pipe. The Nogales wash has fluctuating flows that are controlled by the release of water on the Mexico side of the border. Flows can range from 3 cubic feet per second to 300 cubic feet per second. These unpredictable fluctuations contributed to the design of this project as well as multiple complications during construction. During peak flows the Chula Vista neighborhoods would flood. The intent of the project was to mitigate flooding and provide a new bridge for, use by the neighborhood and local businesses. West Point Contractors and its subcontractors provided the design and construction of the 6 feet diameter caissons, which were drilled 70 feet deep to construct the foundation for the new 210-foot girder bridge. The Nogales Wash channel was also reconstructed and fortified to protect the surrounding neighborhoods. West Point self-performed the construction of a channel embankment, shaping the new alignment of the channel to allow for better flow of the wash. In addition, West Point self-performed reconstruction of roadway approaches on both sides of the new bridge, and completed roadway excavation and roadway embankment according to plan elevations. Sidewalks, guardrail barricade railing, hand railing, striping, and signage were all required and constructed. Sheet piling was also required due to the proximity to the railroad, we also reconstructed the approaching roadway. West Point also reconstructed 1,400 feet of Old Tucson Highway which included excavation using large earth moving equipment, sub-grade with motor graders and large compactors, aggregate base and asphaltic paving.

Scope of Work

• Drilled 6 foot diameter caissons 70 feet deep.
• Constructed new 210 foot girder bridge.
• Placed 3,930 cubic yards concrete for channel embankment.
• Placed 2 foot grouted stone with a 6 inch gravel drain and a 6 inch sand filter for slope embankment protection.
• 2,110 cubic yards of roadway excavation.
• 1,600 cubic yards of roadway embankment.
• Installed 1,200 square feet of sidewalks, 230 linear feet of guardrail, 410 linear feet of barricade railing, and 210 linear feet of hand railing.
• Installed 1,000 linear feet of striping
• Installed 10 signs.
• 40 linear feet of sheet piling.
• Reconstructed 1,400 feet of approaching roadway which included 5,600 square yards of asphalt paving.

Project Challenges

• Fluctuating flows and attempting to control nature, from a safety and constructibility standpoint.
• Unsuitable silty clay conditions on-site were deemed unsuitable for roadway and embankment use.
• Unforeseen utility conflicts: Unisource installed overhead transmission lines over the bridge location prior to drilling caissons.
• Multiple Agency Interactions: USACE, Santa Cruz County, Union Pacific Railroad, City of Nogales, Valle Verde Water.