Director, Oregon Zoo

-- Heidi Rahn

“Equilibrium is team player, committed to keeping a project on schedule and creative when presented with challenging design scenarios.”  

AT EQUILIBRIUM ENGINEERS, we believe that a well-balanced team is essential to both delivering service to our clients and building a resilient business. The size of our firm and diversity of backgrounds of our staff allow us to provide experience-based service in a timely and affordable fashion. We bring a collaborative, creative approach to each new project, and have the depth of knowledge to handle projects of all sizes and degrees of complexity.

Ed Quesenberry, P.E., S.E., is the Founding Principal of Equilibrium Engineers LLC. Ed has over 30 years of structural engineering consulting experience on a broad range of building types, including civic, commercial, educational, medical and housing facilities in California, Oregon and Washington.

Ed graduated from California Polytechnic State University in San Luis Obispo with a Bachelor of Science degree in Architectural Engineering. He is a registered Civil and Structural Engineer in Oregon, Washington, and California, with the ability to obtain registrations in most other states through reciprocity. Ed is Past Allied Member Director on the AIA Portland Board of Directors, has been an Adjunct Faculty Member at Portland State University and currently serves on the Board of Directors of the National Council of Structural Engineers Associations.




JoMarie Farrell, P.E. is an Associate with Equilibrium Engineers LLC. She is a licensed PE in both Oregon and California. JoMarie has over 25 years of structural engineering consulting experience on a broad range of building types, including housing, commercial, medical, educational and government facilities in Oregon, Washington, and Wyoming.

JoMarie has a Bachelor of Science degree in Civil Engineering from The University of Portland. At Equilibrium Engineers she is responsible for the coordination of projects from Schematic Design through Construction Administration. In addition, she is responsible for adhering to the budget and schedule parameters of each project. She serves as the day-to-day contact with the client on all of her projects. Ms. Farrell joined Equilibrium Engineers in 2008.



Jomarie farrell, p.e.

Leif Erickson, S.E. is a Project Manager with Equilibrium Engineers LLC. He is a registered Structural Engineer in Oregon, and Professional Engineer in both Oregon and California. Leif joined Equilibrium Engineers in 2021, bringing with him over 10 years of structural engineering consulting experience in various project types including residential, commercial, medical, educational facilities, seismic retrofit, as well as temporary works and demolition.
Leif has a Master of Engineering degree from Portland State University, focused on structural engineering. At Equilibrium Engineers he is responsible for the coordination of projects from Schematic Design through Construction Administration to meet the goals and budgets of his clients. He has developed a strong background in Building Information Modeling (BIM) and strives to bridge the gap between engineering design and document creation in the most efficient way possible to meet project deadlines and budgets.


project manager

Leif Erickson, S.E.

Derek Jahelka, P.E. is a Structural Designer with Equilibrium Engineers LLC and recently passed his exam to be a licensed PE in the state of Oregon. He has worked on a variety of projects, including mixed-use housing, commercial, educational and government facilities in Oregon and Washington.

Derek earned his Bachelor of Science in Architectural Engineering from The University of Texas at Austin, and a Master of Civil Engineering with a focus on structures from Oregon State University. He enjoys the unique challenges of the collaborative design process and trying to improve the built environment. 
In his free time, he is active in the Young Member Forum of SEAO and enjoys exploring the outdoors of the Pacific Northwest.



Derek Jahelka, P.E.

Cary Crites, E.I.T., is a structural designer with Equilibrium Engineers LLC. Cary has been with Equilibrium since 2017. He has design experience with various construction material types, including concrete, steel, wood, masonry, and mass timber. 

Cary has a Bachelor of Science degree in Civil Engineering from California State University Fullerton with an emphasis in structural design and attended graduate school at Portland State University, where he was a research assistant focusing on mass timber structural systems. As a structural designer, Cary has been exposed to structural design on a broad range of building types and sizes and enjoys the variety of challenges each one brings. He is a member of the Structural Engineers Association of Oregon and has participated in the ACE Mentor Program.

When he’s not crunching numbers, Cary enjoys getting outdoors, boxing, and seeking out new restaurants and coffee shops to try.



Cary Crites, E.I.T.

Mark Forster is the BIM Manager with Equilibrium Engineers LLC and is responsible for AutoCAD drafting and Revit modeling. He is also responsible for the setup and execution of Autodesk and add-in products within the firm, and manages our company’s BIM standards. Mark joined Equilibrium Engineers in 2017.

Starting on the path of becoming a computer programmer, Mark eventually took more of an interest in the drafting field and eventually graduated from PCC Sylvania with an Associate degree in Architectural Drafting. His skills as a designer and CAD technician vastly grew over time. His expertise began by learning the art of hand drafting, extended to learning AutoCAD Version 2.5, and has continued with every new software release. Throughout his 30 year drafting/designer career, his knowledge has expanded to multiple platforms, including DCA, Land Desktop Development, Civil 3D, MicroStation, and Revit. 

When he’s not building 3D Revit models, Mark enjoys wood-working and small remodeling projects to express his passions outside of work.


BIM Manager


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16325 Boones Ferry Rd.
Lake Oswego, Oregon