Holden Orler and Mac Sullivan, Two ENR Top Young Professionals, One Energy and Infrastructure Team

ARCO/Murray is proud to announce that Holden Orler and Mac Sullivan, both Vice Presidents on the Energy & Infrastructure team, have each been named a 2027 Top Young Professional by ENR Midwest. The annual program recognizes 20 industry professionals under 40 across the region for leadership, career progress, and community involvement, and each honoree will be profiled in the January 2027 edition of ENR Midwest.

Their recognition speaks to the team they’ve helped build. For almost a decade, these two young engineers have worked side by side, taking on unprecedented projects and turning them into the capabilities that define the Energy & Infrastructure team today.

Building Where No Playbook Existed

Holden joined ARCO/Murray in 2018 and Mac in 2019, each with a civil engineering degree and a shared instinct for work that hadn’t been done before. Holden earned a B.S. in Civil Engineering and an M.S. in Structural Engineering from the University of Illinois and began his career as a structural engineer. Mac earned a B.S. in Civil Engineering from the University of Notre Dame and gained early field experience through internships with two of the nation’s largest general contractors.

Their first proving ground was controlled environment agriculture (CEA). At the time, no general contractor in the U.S. had proven a delivery model for large-scale hydroponic greenhouses and indoor cultivation facilities. Together with the team around them, they helped make ARCO/Murray the leading builder in the sector, with more than 50 technically complex facilities across the country.

What they learned in CEA became the foundation for everything that followed. Integrating climate control, automation, specialized utilities, and process systems prepared the team to move into renewable natural gas, battery energy storage, industrial water reuse, municipal wastewater, and most recently behind-the-meter power plants. Each new market started the same way: spot the emerging need early, build the technical expertise, and turn a first project into a repeatable capability.

Holden Orler: Building The Capabilities Behind The Work

Holden, 34, brings an engineer’s mindset to every project. That perspective shapes his leadership approach: aligning engineering, design, construction, commissioning, and operations early in the process, particularly on complex projects where there is no established playbook.

As Vice President, Holden has provided operational leadership for approximately $750 million in active and completed projects. His portfolio includes two controlled-environment agriculture greenhouse developments that transformed challenging urban sites into productive community assets: one on the remediated grounds of a former steel mill in Baltimore and another in Chicago’s historic Pullman neighborhood. Both projects support local food production while driving economic investment and job creation in their communities.

Holden also helped establish two of the company’s specialty practices. He was an early advocate for the creation of Second Order Controls (2OC), ARCO/Murray’s controls and commissioning group, after recognizing that commissioning, startup, and the transition from construction to operations were consistent pain points for clients on complex projects. By championing a more integrated approach to controls, commissioning, and operational readiness, he helped position 2OC as a significant competitive differentiator for the firm. Holden also helped launch BlueWTR, the firm’s water and wastewater practice, which has delivered sustainable water reuse solutions across the country and played a key role in securing ARCO/Murray’s first municipal water treatment project, a $150 million facility in Wylie, Texas.

Mac Sullivan: Turning New Markets Into Platforms

At 31, Mac has shown an uncommon ability to build a business within a business. He played a foundational role in building ARCO/Murray’s CEA platform, helping turn an emerging, largely untested market into one of the company’s core strengths.

As Vice President, Mac now provides operational leadership for approximately $200 million in active energy and infrastructure projects, spanning CEA, renewable natural gas, battery energy storage, and water and wastewater. He is also spearheading ARCO/Murray’s new long-haul fiber infrastructure platform, building the capability from the ground up.

Mac’s focus is on the systems behind the projects: the processes, teams, and operating structures that let the team scale with discipline. He shares that knowledge across the industry through the Resource Innovation Institute, American Biogas Council, and RNG Coalition, and sharpened his own leadership through the Thayer Leadership program at West Point.

Leading Beyond The Jobsite

The same instincts that drive Holden and Mac at work show up in their communities. Holden and his wife are passionate advocates for children with disabilities, a commitment rooted in their own family’s experience. Holden and his team at ARCO are key sponsors of the annual fundraiser for Easterseals DuPage & Fox Valley, which provides therapy, developmental services, and resources for children and adults with disabilities.

After the unexpected passing of his brother, Declan, Mac and his sister founded the Declan Drumm Sullivan Memorial Fund while still in high school. Its annual Chicago fundraiser, No Ordinary Evening, has raised more than $15 million for Horizons for Youth and now generates over $1 million each year.

Mac also serves on the Horizons for Youth board. He has brought more than 100 ARCO/Murray employees into the cause, and roughly a quarter of the event’s annual revenue now comes from the ARCO/Murray community.

A Team Built To Lead What’s Next

Holden and Mac each earned this recognition on their own merits. Together, their careers show how the Energy & Infrastructure team was built: by moving early into emerging markets, developing people alongside capabilities, and turning first-of-their-kind projects into lasting platforms. Grid modernization, water scarcity, aging infrastructure, and the energy demands of data centers are reshaping the built environment. The team Holden and Mac helped build is ready to lead in each of those areas.

Congratulations to Holden and Mac on this well-deserved recognition!

See the full list of ENR Midwest’s 2027 Top Young Professionals in the online edition: ENR Midwest Announces Top Young Pros for 2027