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Senior Mechanical Engineer

Fermilab · Batavia, IL · $111,400–$146,600 a year · Full time

Posted Sep 9, 2026 · We last checked this listing on Oct 6, 2026

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Likely interview questions for this role

Written from this job description, not a generic list. Each one notes what the interviewer is really checking.

About your past

Tell me about an engineering project where you had to come up with a new approach rather than reuse a standard design.

What they are checking: Whether they bring the creativity the posting asks for on upper-level infrastructure projects.

Tell me about a time you supervised engineers or managed a group. How did you develop them?

What they are checking: Whether they are ready to lead people, since the role may manage an engineering group.

Tell me about a project that went wrong. What did you learn?

What they are checking: Whether they reflect honestly on failures and apply lessons to future work.

What would you do

A subcontractor proposes a substitution that saves money but changes performance. How do you decide?

What they are checking: Whether they evaluate substitutions on engineering merit and lifecycle cost, not just price.

An aging HVAC or utility system serving a lab building is failing more often. How would you approach replacing it with minimal disruption?

What they are checking: Whether they can plan phased work that keeps research facilities running.

About the work

Walk me through how you'd take a facility mechanical project from design through installation and initial operation.

What they are checking: Whether they understand every phase, including design review, procurement, testing and turnover.

How do you build compliance with DOE orders and federal, state and local codes into a design?

What they are checking: Whether code compliance is designed in from the start rather than checked at the end.

How do you run a design review that catches real problems?

What they are checking: Whether they bring in the right reviewers and focus on risk, not just formatting.

What engineering calculations do you check by hand even when you have software?

What they are checking: Whether they keep sound engineering judgment rather than trusting tools blindly.

How do you write a specification for procurement that gets you what you need?

What they are checking: Whether their specifications are clear and complete enough to avoid disputes and poor substitutes.

Practice this interview out loud.

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The full job description

As published by Fermilab.

The expected hiring range for this position is: $111,400.00-$146,600.00. Please note that the pay range information is a general guideline only. The pay offered to a selected candidate will be determined based on factors such the scope and responsibilities of the position, qualifications of the selected candidate, business considerations, internal equity, and external market pay for comparable jobs. About the Role: The Fermilab Infrastructure Services Division (ISD) is seeking a Senior Mechanical Engineer . This individual is responsible for upper-level engineering projects requiring engineering creativity in developing innovative concepts and techniques. The ISD Senior Mechanical Engineer leads and contributes to projects in areas such as design, design review, procurement, manufacture, installation, test, and initial operations of a project with extensive & diversified engineering requirements in compliance with all applicable local, state, and federal regulations, requirements and standards, and all Department of Energy (DOE) orders. This role may oversee sub-contractors or supervise/manage an engineering group. What your day-to-day as a Senior Mechanical Engineer at Fermilab will look like: • Analyzing data and performing engineering calculations. Developing designs of specific parts, components, or phases of a project. • Developing specifications, designs, and documents for major and technically complex engineering projects and design solutions. Work involves a variety of moderately complex engineering techniques. • Planning projects from inception to completion and brings them to operating status. Estimating manpower, scheduling work, coordinating and directing technicians. • Providing technical direction to draftsmen, designers, engineering associates, technicians, or less senior engineers. Coordinating and/or supervising technicians and other engineers, as assigned. May supervise an engineering/technical team or department, as assigned. • Researching and proposing solutions to engineering problems and provides analyses of alternatives to manager(s). • Participating in procurement, as well as manufacturing, installation, testing, and operation. • Assisting or leading in the development of cost estimates, as well as the monitoring and/or management of budgetary obligations. • Reviewing and approving work before hardware and financial resources are committed, ensuring conformance to specifications and cost/time constraints. • Providing and implementing changes in methods, design, or equipment in assigned area and contributes to the overall safety and completion of assignments. • Contributing to setting lab-wide engineering policies, safety standards or technical standards. • Serving on safety panels, review committees, and other subcommittees as assigned. • May participate in technical conferences and publication. • May provide supervision or leadership of a team including hiring, promotions, performance reviews, training, disciplinary actions, team exits, and other duties as assigned. • Performing other duties as assigned by supervisor. • Abiding by and being responsible for performing all duties in accordance with all environmental, health and safety regulations and practices pertinent to this position. Essential Skills and Competencies for Success: • Bachelor’s or Master’s in an applicable Engineering discipline from an ABET accredited institution • 5-10 years of engineering experience working at an MEP consulting firm. Applicable Knowledge, Skills and Abilities Required: • In-depth knowledge and proficiency in application of theories, concepts, principles, and methodology for the engineering discipline. • Possess extensive project planning skills in developing specifications and documents for major and technically complex, high-level, and highly visible engineering projects and engineering design solutions. • Ability to perform a variety of complex and advanced engineering techniques. • Experience with AutoCAD required. Experience with Revit is a plus. • Professional Engineer licensure is required. Licensure in State of Illinois is a plus. The successful candidate will have experience in one or more of the following related areas: • Design of plumbing systems required • Working knowledge of building codes related to plumbing and mechanical systems required • Design of hydronic piping systems desired • Design of HVAC systems desired • Experience with energy modeling/HVAC software desired • Exposure to Building Commissioning desired • Familiarity with ASHRAE requirements and applications desired Work Arrangement: Please note that the described work arrangement is subject to change based on business needs and is not guaranteed to be final. • Onsite : This is an onsite role, and the candidate must be able to work from our Batavia office. Benefits/Perks: Fermilab offers a competitive and comprehensive benefits program, including: • Medical, Dental, Vision and Flexible Spending Accounts • Paid time off • Life insurance • Short and Long-term disability insurance • Retirement benefits • Onsite day care Why Fermilab: Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. We support discovery science experiments in Illinois and locations around the world, including deep underground mines in South Dakota and Canada, mountaintops in Arizona and Chile, CERN in Europe and the South Pole. Pre-Employment Screening: Drug-Free Workplace & Pre-Employment Screening Fermilab is dedicated to fostering a safe, productive and drug-free environment. An offer of employment is contingent upon the successful completion of a background check and drug screening. HSPD-12 In accordance with Homeland Security Presidential Directive 12 (HSPD-12) new employees are required to obtain and maintain a HSPD-12 Personal Identity Verification (PIV) Credential. To obtain this credential, new employees must successfully complete and pass a federal background check investigation. This investigation includes a declaration of illegal drug activities, including use, supply, possession, or manufacture. This includes marijuana and cannabis derivatives, which are still considered illegal under federal law, regardless of state laws. Failure to obtain or maintain such government access authorization could result in the withdrawal of a job offer or future termination of employment. Foreign Government Sponsored Activities Fermilab employees, and certain guest researchers and contractors, are subject to particular restrictions related to participation in Foreign Government Sponsored or Affiliated Activities, as defined and detailed in United States Department of Energy Order 486.1A. Such individuals will be asked to disclose any participation for review by Fermilab's Office of General Counsel. REAL-ID Requirement for access to Fermilab Campus Fermilab requires all members of the public to produce a REAL-ID, or equivalent, to access the Fermilab Campus for interviews or career events. A list of acceptable forms of ID can be found here: https://get-connected.fnal.gov/wp-content/uploads/2021/09/REALID-Documents.pdf . If a candidate is selected for an interview but does not possess any of the equivalent documents, we may schedule a virtual interview. Equal Opportunity Statement Fermilab is an equal opportunity employer. We evaluate qualified applicants without regard to race, color, religion, sex, age, national origin, disability, veteran status, genetic information, and other legally protected categories.

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