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Who are we?
ZT Consulting Group is a Southern California based consulting engineering company that provides services to public transportation agencies. Consider us your partner, and as such we are always on call and always available for everything from simple brainstorming sessions to representing you during meetings with stakeholders.


The majority of our staff has served and completed numerous public projects within the State of California over the past decade. We understand the requirements, challenges, and objectives of public projects.


Our Certifications

ZTC staff have qualifications and certifications from various nationally recognized organizations.



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Principal Engineer

Farzad Tasbihgoo, PhD, PE, CQA, CWI, PCI III 

Farzad Tasbihgoo is a registered civil engineer with about two decades of work experience in structure construction and engineering design. He has a strong engineering design background with extensive experience in source inspection and quality assurance services. 

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Structural Material Representative

Derick Hobbs, CQA, EIT, CQA, ACI I, PCI II

Derick is an experienced Assistant Quality Engineer (AQE) with over 4 years of experience. He has a degree in Civil Engineering and holds an E.I.T Certification with the State of California. Derick has developed knowledge of Caltrans Standard Specifications while working as an AQE.

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Quality Assurance Technician

Richard Corona

Richard is an experienced source inspector with more than 20 years of experience working for Caltrans Material Testing Engineering Services (METS) in the Office of Structural Materials (OSM), Los Angeles branch. Richard is among few QA inspectors that started working for Caltrans METS/OSM.

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Lab Manager

David Ramirez, ACI I, PCI I, PCI II

David is an experienced Quality Assurance (QA) precast inspector with about 12 years of precast fabrication and inspection. He was a Quality Control Manager (QCM) for a major precast fabricator for about 2 years and has been working as QA inspector for the past year. He has extensive knowledge of Caltrans Specification for Concrete and Precast Concrete Institute Certified Quality Control Level II (PCI II).

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Quality Assurance Steel Inspector

Eric Sanabria, CWI -NDT Level II UT/PT/MT 

Eric Sanabria is an experienced Non-Destructive Testing (NDT) Technician. Eric has nearly a decade of NDT experience across multiple industries and methods, specializing in the ultrasonic inspection of complex weld geometries and compositions. 

Quality Assurance Lead Inspector

Andrew Soria, PCI III, ACI I, CWI, NACE 2

Andrew is an experienced precast concrete inspector with about 16 years of experience in mix design, concrete placing, sampling, testing, inspection, and quality control of precast concrete panels. He is Precast Concrete Institute Certified Quality Control Level III (PCI III), the highest precast inspection certification an inspector can achieve.

Business Development

Ileen Robles 

Ileen has extensive knowledge in business development. She prepares all of ZTC RFPs/proposals and participates in networking events. She oversees all day-to-day functions of ZTC’s offices. She is currently pursuing her degree in marketing.

Quality Assurance Inspector

Paul Mortsolf, PCI II, ACI I, NACE 2

Paul is an experienced QA precast/prestress concrete inspector with about 15 years of precast/prestress production and inspection. He was the QCM at a major precast fabricator for about 10 years and has been working as a QA inspector for the past 4 years. He has extensive knowledge of Caltrans and NPCA Specification for concrete and precast/prestress fabrication.

Quality Assurance Steel Inspector

Nathan Liszewski, CWI, NDT Level II UT/MT, NACE Lv. 1

Started in the welding industry in 2007 and made the progression from certified welder to 2 Associates Degrees, one for Welding technology and another for Quality Engineering. Qualified in multiple disciplines of inspection, including Non-destructive testing (MT, PT, UT), NACE coating inspection, Bolt inspection, and has been a CWI since 2010 with recent endorsement as an AWS D1.8 Bridge Welding Inspector. Has worked in a variety of weld related industries, with continued progression of responsibilities. Industry experience in heavy plate equipment manufacturing, petrol chemical facilities to include piping and vessels, and construction, including bridge fabrication. Expertise in welding fabrication, quality control functions, quality assurance, verification, and quality systems compliances.

Quality Assurance Lead Steel Inspector

William (Bill) Kent, CWI, ACI I, NDT Level II UT/MT/PT/RT

Bill has more than 37 years of international experience providing Quality Assurance/Quality Control (QA/QC) welding inspection and nondestructive testing (NDT) services on-site and in fabrication facilities for major steel construction projects. Mr. Kent has significant experience performing quality assurance inspection and nondestructive testing during field erection and shop fabrication of major steel bridge projects for various Departments of Transportation and Bridge Authorities. He has experience as the Lead Inspector in the fabrication of Facture Critical (FCM) bridge components in accordance AWS D1.5. He has wide-ranging experience in precast concrete inspection for such items as HOV Interchange improvements, Roadway and Bridge widening, Retaining Walls and Street and Drainage Improvements.

Quality Assurance Material Specialist

Glen Weldon

Glen has over 46 years working in material verification and testing. Mr. Weldon is currently a Consultant for ZT Consulting Group, Inc. (ZTC). He performs internal Quality Control and Assurance. He assists in the verification of testing standards and results for all source inspected materials.

Cole Hofberg

Cole is training as a Quality Engineer.  He has a Bachelor’s degree in Civil Engineering from University of California, Davis and holds an E.I.T. Certification with the State of California.



ZT Consulting Group, Inc. (ZTC) is a consulting engineering company that specializes in Quality Assurance & Source Inspection (QA, QV, IQA, QMP, SIQMP, QAP and QAM), Forensic Engineering, and Structural Health Monitoring (SHM). At ZTC we are a group of professional registered engineers and technicians with decades of experience in design, construction, and fabrication support services.

Source Inspection
Structural Health Monitoring


Projects Completed




San Bernardino County Transportation Authority (SBCTA)

Orange County Transportation Authority (OCTA)

Alameda Corridor East

Construction Authority

City of Los Angeles


Madera County

City of Monterey

Los Angeles County Metropolitan Transportation Authority (LACMTA)

City of Hanford

Riverside County Transportation Department


Port Authority of New York & New Jersey



Please send your email requests to


For any inquiries, questions or commendations, please fill out the following form:

Office Locations

Los Angeles Office     

1041 E Green Street

Suite 204

Pasadena, CA 91106

Tel | (626) 714 - 7181


San Bernardino Office   

850 W. 9th St.

Upland, CA 91786


Tel | (909) 351-2078


Fax | (818) 369 - 6867

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We are always looking for an AQE, NDT UT/MT Level II, and Quality Precast Inspector. Please send resumes to:

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