Zelen provides engineering and consulting services in the southwest including Arizona, California, New Mexico, Texas and Colorado. Zelen is a small firm that is equipped to handle larger projects normally handled by larger, national consulting and engineering firms. Our clients vary from small, family businesses to school districts and oil companies. Zelen’s ability to manage a diverse array of projects from small to large, is found in its employees and associates who pride themselves in their work and provide personalized service. Our company philosophy is simple, treat the client as you would want to be treated, with respect and by experienced individuals who understand a client’s needs, not the billability requirement of a corporate office. We hold the following certification and registrations: State of Arizona, Board of Technical Registration, Firm Registration Number 11402-0 Arizona Department of Environmental Quality, Consultant Prequalification #1249 Arizona Department of Environmental Quality, Permanent Tank Service Provider Certification #D00127 California Certification Number C2358795