Senior Mechanical Engineer

Work with Us. Change the World.

At AECOM, we're delivering a better world. Whether improving your commute, keeping the lights on, providing access to clean water, or transforming skylines, our work helps people and communities thrive. We are the world's trusted infrastructure consulting firm, partnering with clients to solve the world’s most complex challenges and build legacies for future generations.

There has never been a better time to be at AECOM. With accelerating infrastructure investment worldwide, our services are in great demand. We invite you to bring your bold ideas and big dreams and become part of a global team of over 50,000 planners, designers, engineers, scientists, digital innovators, program and construction managers and other professionals delivering projects that create a positive and tangible impact around the world.

We're one global team driven by our common purpose to deliver a better world. Join us.

AECOM is seeking a Senior Mechanical Engineer based in Orange, California. This is a Hybrid position.

Join our dynamic team supporting exciting projects!  Work independently and make technical decisions based on building code interpretation as well as company, client, and industry standard practices. Mentor and teach junior engineers. Grow your career with us in our Building+ Places group. 

The Senior Mechanical Engineer will be responsible for the following but not limited to;

• Design of heating, ventilation and air conditioning systems as well as plumbing systems for large projects federal government, commercial, and institutional facilities
• Perform Construction Administration services, including review of shop drawings, RFI’s and review of contractor proposed change orders
• Evaluate feasibility of alternative design approaches in conjunction with senior team members
• Perform site/field visits to ascertain existing conditions including equipment condition evaluations
• Organize/plan projects to ensure quality controls and project criteria are met and within budget  
• Assist in preparing proposals and presenting to Clients
• Assist with mentoring of junior staff within the Mechanical Department
• Review and edit specifications
• Interact and work with a diverse set of clients and subcontractors
• Serves as lead engineer on mid - to large size projects.

Minimum Requirements

• Bachelor’s degree in Mechanical Engineering from an ABET accredited Mechanical Engineering Program
• 8+ years of experience in mechanical design of HVAC and Plumbing systems or demonstrated equivalency of experience and/or education
• Professional Engineer (PE)
• This position requires U.S. citizenship due to federal contract/security requirements

Preferred Requirements

• 10+ years of experience in mechanical design of HVAC and Plumbing systems
• Experience using AutoCAD and Revit
• Ability to interact with others on a multi-discipline team
• Ability to work on multiple projects at once
• Excellent communications skills with the ability to present designs to clients
• Good time management skills, a strong work ethic and attention to detail
• Proficient in Building Load Calculation and Energy Modeling
• Proficient in the design of plumbing systems including sanitary, storm, and water distribution systems
• Energy Modeling experience a plus
• Cost estimating experience a plus
• Experience with Design-Build and other Alternate Delivery practices a plus
• Experience with Instrumentation and Controls design a plus
• Excellent Communications Skills with the ability to present designs to clients
• Additional Industry Certifications such as LEED AP, CxA or CEM
• Federal experience; NAVFAC, USACE, VAMC, DOD or USAF experience preferred
• Experience in the following markets:
  • Healthcare
  • Data Centers / Mission Critical
  • Higher Education
  • Corporate Commercial / Mixed Use
  • Science & Technology (Labs)

• Sponsorship is not available for this position
• U.S Citizenship required due to the nature of the work

At AECOM, we are committed to maintaining a secure and trustworthy recruitment process and take any fraudulent hiring activity seriously. To support this commitment, all newly hired employees are required to attend an in-person Day 1 onboarding at an AECOM office location as a condition of employment.

About AECOM 

AECOM is proud to offer comprehensive benefits to meet the diverse needs of our employees. Depending on your employment status, AECOM benefits may include medical, dental, vision, life, AD&D, disability benefits, paid time off, leaves of absences, voluntary benefits, perks, flexible work options, well-being resources, employee assistance program, business travel insurance, service recognition awards, retirement savings plan, and employee stock purchase plan. 

AECOM is the global infrastructure leader, committed to delivering a better world. As a trusted professional services firm powered by deep technical abilities, we solve our clients’ complex challenges in water, environment, energy, transportation and buildings. Our teams partner with public- and private-sector clients to create innovative, sustainable and resilient solutions throughout the project lifecycle – from advisory, planning, design and engineering to program and construction management. AECOM is a Fortune 500 firm that had revenue of $16.1 billion in fiscal year 2025. Learn more at aecom.com. 

What makes AECOM a great place to work 

You will be part of a global team that champions your growth and career ambitions. Work on groundbreaking projects - both in your local community and on a global scale - that are transforming our industry and shaping the future. With cutting-edge technology and a network of experts, you’ll have the resources to make a real impact. Our award-winning training and development programs are designed to expand your technical expertise and leadership skills, helping you build the career you’ve always envisioned. Here, you’ll find a welcoming workplace built on respect, collaboration and community—where you have the freedom to grow in a world of opportunity. 

As an Equal Opportunity Employer, we believe in your potential and are here to help you achieve it. All your information will be kept confidential according to EEO guidelines.