Schultz Creek Drainage Improvements, Arizona 2024

The Schultz Creek Drainage Improvements at US Highway 180 CMAR (the Project) is a transformative achievement in flood mitigation for the City of Flagstaff. Built in response to devastating post-wildfire flooding, this project delivered urgently needed infrastructure to protect the West Flagstaff community.

PROJECT INFORMATION
Location:
Flagstaff, AZ
PROJECT TEAM
Owner:
City of Flagstaff
Contractor:
J. Banicki Construction, Inc.
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The Challenge

After the 2022 Pipeline Fire, that burned 26,523 acres and re-burned the 2010 Schultz Fire scar in Coconino National Forest, Flagstaff faced repeated flooding that threatened homes, businesses, and critical roadways. A double barrel 8’x5’ box culvert needed to be quickly installed under Highway 180, one of the busiest highways in Flagstaff.

The most challenging aspect of this project involved the installation of box culverts within a narrow 40-foot easement between two critical buildings – the historic Grand Canyon Trust (the second oldest homestead in Flagstaff) and Fire Station 5. In addition to working with little space under an accelerated timeline, this was not a straight run of culvert and required the contractor to install around existing utilities.

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The Solution

Rinker Engineering recommended the contractor use smaller precast box culvert sections to make it easier to install around existing utilities. Rinker Materials supplied a mix of 8’ and 4’ sections. 45-degree precast bends were also supplied to meet the layout requirements. J. Banicki was able to mitigate disruptions to those traveling on Highway 180 by being able to backfill and pave immediately after setting the precast box culvert sections, allowing them to finish this project earlier than if they had used the traditional cast-in-place method.

This project was the inaugural use of ADOT’s new SD 6.20 specification for precast reinforced concrete box culverts. Required extensive material submittals, engineering calculations, and approvals to ensure compliance. J. Banicki partnered with ADOT and Rinker Materials to streamline the implementation process. Set a benchmark for future flood mitigation projects across Arizona.

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J. Banicki designed a core-drilled soldier pile support of excavation (SOE) interface that supported both directions of traffic on US-180.
Project Timeline

J. Banicki mobilized and began construction on March 25, 2024, just as snow began to melt on the San Francisco Peaks, Arizona’s tallest mountain range. Equipped with detailed utility protection, lift-and-lay, and relocation plans from preconstruction, J. Banicki achieved the rapid installation of all 848 LF of 8’ x 5’ precast double-barrel RCBs by July 13, 2024. The installation of all 848 LF of RCBs was completed by July 13, 2024 – well before peak monsoon season – after working 12 to 14-hour shifts seven days a week from late March onward. This unwavering commitment to an intense work schedule was essential to achieving the project’s primary milestone. Following the completion of the RCB alignment, J. Banicki turned its attention to finalizing all surface and environmental features. This included inflow and outflow structures, CIP headwalls, site restoration, landscaping, and hydroseeding, which were fully completed on October 15, 2024. This comprehensive project closeout ensured long-term site resilience and a seamless integration with the surrounding landscape, providing the community with robust flood protection and restored natural aesthetics.

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The Rinker Advantage

Rinker Materials’ commitment to excellence fostered collaboration among key stakeholders in the development of Arizona’s first precast box culvert standard specification. As the first project to implement this standard, Ardurra, J. Banicki Construction, ADOT, and the City of Flagstaff had the opportunity to experience the quality of precast drainage products firsthand—through detailed engineering submittals, in-plant quality control, and the robust structural design outlined in this long-awaited local standard.

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For additional information regarding this successful ADOT project, please contact:

Adrianna Lash, Technical Resource Specialist – Rinker Materials Arizona Region
Adrianna.Lash@RinkerPipe.com

Product(s) Used:


REINFORCED CONCRETE BOX CULVERTS – U.S.
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