Day & Zimmermann

Witt LeFew
Home 3975 Virginia Mallory Drive Suite 200 Chantilly VA 20151 Work Phone: (703) 955-5712 Website:


Founded in 1901, Day & Zimmermann is a family-owned company with a workforce of 43,000 specializing in construction & engineering, operations & maintenance, staffing, security and defense solutions for leading corporations and governments around the world. Operating from more than 150 worldwide locations with 2.5 Billion USD in revenue, Day & Zimmermann is currently ranked as one of the largest private companies in the U.S. by Forbes. Headquartered in Philadelphia, PA, our first work was to develop “Betterment Reports” that helped modernize American factories. Today, we are still in the business of betterment—maintaining the nation’s power infrastructure, protecting American freedoms and accelerating innovation around the world. We do what we say ®.

We offer full-scope engineering and design services for projects that range from new facilities to revamps and upgrades. Our experienced engineering resources seamlessly deliver strategic planning, conceptual engineering, front-end engineering, detailed engineering, 3D digital facility lifecycle solutions, and more. Typical projects encompass small to mid-sized capital expenditure (capex) projects, from $100,000 up to $100 million total installed cost (TIC). We are a full service EPCm and maintenance provider, and have the flexibility to execute EPCm projects directly with the customer or in collaboration with other EPC firms.


Day & Zimmermann is currently ranked #66 in Top 400 Contractors and #157 in Top 500 Design Firms (“Engineering News-Record” Industry Rankings, Fall 2018), and have performed an average of 1M engineering hours annually since 2015.

Company Size/NAICS Codes

Large Business

NAICS codes: 541330, 238990










Key Words/Phrases

Conceptual Engineering

Front-end Loading

Work Packaging

Quality Control Packages

Detailed Design

30/60/90% Design Staging


Process Simulation

Digital Asset Management


3D Design

Laser Scanning

Process Hazards Analysis (PHA/HAZOP) and Facilitation

Balance of plant (BOP) projects/utilities/infrastructure

Project Management


Safety controls

LOPA and Safety Integrated Level (SIL) Analysis

Relief Device Analysis, Sizing, and Validation

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3975 Virginia Mallory Drive Suite 200 Chantilly VA 20151