Engineering Excellence & Legacy Awards

The Tucson Boulevard Diversion Structure in Pima County manages nearly 25 million gallons of wastewater daily, balancing flows between two major interceptor sewers. Over time, it became odorous, corroded, and hazardous due to excessive hydrogen sulfide (H2S) gas produced within, leading to non-functional gates and risky confined space entries for flow adjustments. Addressing odor, corrosion, and safety became a priority.

Dibble designed a new system that improved hydraulic performance by separating bends and diversions into three structures, reducing energy losses, turbulence, off-gassing, and consequently mitigating odors, corrosion, and improving safety. The new structures, made of pre-cast polymer concrete and fiberglass, prevent corrosion. Accessible stop gates through a large hatch eliminated the need for confined space entry, making maintenance safer.

Coordination between the County, Dibble, and Hunter Contracting was crucial during design and construction due to extensive wastewater bypass, limited workspace, and unexpected soil conditions. Despite supply chain and permitting challenges, the project was completed on time and within budget. With the new system in place, odors are mitigated, corrosion is addressed, safety is improved, and the community can breathe easily.

The goal of this project was to create a comprehensive water solu􀦞on by transi􀦞oning from groundwater to u􀦞lizing water from the Colorado River via the CAP Canal. The project team performed the ini􀦞al analysis, developed the solu􀦞on, and designed and oversaw the construc􀦞on of a 30-inch transmission main, a cri􀦞cal piece of the overall infrastructure

The Intersection of 107th Avenue and McDowell Road serves as a vital point of connectivity to the City of Avondale and neighboring communities such as Goodyear, Phoenix, and Tolleson.  The intersection provides regional connecitvity to/from Metro Phoenix area and serves as direct access to Phoenix Raceway; Avondale West Valley Health Quarter, which is an epicenter of healthcare services providing jobs for more than 40,000 healthcare workers; commercial/office/retail known as The ROW on McDowell Rd: Friendship Park; and various residential communities. 

State Route 24 is a controlled access urban principal freeway that provides a vital link between the southeastern Maricopa and northern Pinal County communities to the Phoenix metropolitan area for over 150,000 residents. The five-mile interim expansion, running from Ellsworth Road to Ironwood Drive, was designed to the ultimate freeway configuration, with three general purpose lanes, one auxiliary lane and one HOV lane in each direction. Then the design was purposefully scaled back to the interim design with two lanes in each direction until funding becomes available for the ultimate build-out. When funds become available, the additional lanes and overpasses to create the ultimate freeway can be seamlessly added with minimal throwaway and inconvenience to drivers.

The goal of this project was to create a comprehensive water solu􀦞on by transi􀦞oning from groundwater to u􀦞lizing water from the Colorado River via the CAP Canal. The project team performed the ini􀦞al analysis, developed the solu􀦞on, and designed and oversaw the construc􀦞on of a 30-inch transmission main, a cri􀦞cal piece of the overall infrastructure

The goal of this project was to create a comprehensive water solu􀦞on by transi􀦞oning from groundwater to u􀦞lizing water from the Colorado River via the CAP Canal. The project team performed the ini􀦞al analysis, developed the solu􀦞on, and designed and oversaw the construc􀦞on of a 30-inch transmission main, a cri􀦞cal piece of the overall infrastructure

A two-mile extension of the PHX Sky Train® connects 14 million travelers annually to the Phoenix Sky Harbor International Airport’s consolidated Rental Car Center (RCC) and Ground Transportation Center. Gannett Fleming was the fixed-facilities designer for PHX Sky Train® Stage 2, providing guideway and support structure design. The Stage 2 guideway serves two new stations and a future station, including the RCC, which was built on the upper level of the existing structure. The project used a CM-at-Risk (CMAR) model to support fast-track delivery, enabling early identification and mitigation of constructability issues and allowing for overlapping design and construction processes

For years, the City of Phoenix has been providing water and wastewater services to the West Anthem area through a service agreement with EPCOR. To establish a direct connection, Phoenix proposed an ambitious project. 

• Five miles of 18-inch and 21-inch gravity sewer main

• Two miles of 36-inch and 24-inch water transmission main

• New lift station and one mile of 8-inch force mains

• Booster pump station upgrades

Now complete, these improvements empower the City to provide direct services to the West Anthem area, simplify future connections, and support thriving development. 

Entellus completed the study for the entire system and final design and construction administration for the north pipelines and booster pump station improvements. 

The need to improve this section of Broadway Boulevard

for enhanced mobility and safety was first identified in the

1980s. The project was included in the 1997 Pima County

Bond program and subsequently approved by voters in

2006 as part of the Regional Transportation Authority

program.

Focused on increased capacity, safety, and

preservation to create a true multi-modal corridor

The original concept entailed an eight-lane divided arterial,

widened primarily to one side. However, this approach

would have resulted in the acquisition and demolition of

more than 90 properties. In an effort to minimize these

impacts, the concept went through many iterations and

entailed extensive collaboration. Ultimately, Broadway was

designed as a six-lane roadway along a new curvilinear

alignment that resulted in more than 70 properties saved

from demolition.

Within this narrowed footprint, the design team was

also able to accommodate a 96” diameter storm drain,

raised median, bus stop pullouts, buffered bike lanes,

widened and accessible sidewalks, lighting, native

landscape, and public art. The newly-designed Broadway

Boulevard improves vehicular capacity, providing safe

and comfortable access for pedestrians and cyclists while

preserving the existing character of the area, creating a

true multi-modal corridor.

Tucson’s new diverging diamond interchange (DDI) at I-10 and Houghton Road is the first of its kind in southern Arizona and just the second DDI of its kind in Arizona. The $24 million interchange replaced a 50-year-old two-lane bridge, increasing daily capacity from 8,000 to 50,000 vehicles. In the DDI configuration, each direction of Houghton Road traffic crosses to the left side over the freeway. This allows for left turns onto the on ramps without waiting at an additional traffic signal or having to turn across traffic. It is overwhelmingly supported by local residents.

A two-mile extension of the PHX Sky Train® connects 14 million travelers annually to the Phoenix Sky Harbor International Airport’s consolidated Rental Car Center (RCC) and Ground Transportation Center. Gannett Fleming was the fixed-facilities designer for PHX Sky Train® Stage 2, providing guideway and support structure design. The Stage 2 guideway serves two new stations and a future station, including the RCC, which was built on the upper level of the existing structure. The project used a CM-at-Risk (CMAR) model to support fast-track delivery, enabling early identification and mitigation of constructability issues and allowing for overlapping design and construction processes