Our Staff
Leadership
GSG’s management team are licensed professionals within a broad range of practice areas and specialties who collaboratively work together to achieve one goal…RESULTS.
Our management team is focused on gaining a deeper understanding of the unique challenges faced by our clients in order to deliver strategic, sustainable, and technically sound solutions that balance the requirements of compliance, risk management and organizational needs. They do this by applying their individual and collective knowledge and experience, one of the firm’s most valuable assets.
To find out more about our key staff, click on the area of the staff members name to read their full biography.
Guillermo Garcia
Principal, Chief Executive Officer

Education:
- Masters of Science, Occupational Safety, University of Wisconsin – Whitewater
Registrations:
- Certified Asbestos Management Planner
- Certified AHERA Inspector
- Licensed Asbestos Project Manager
- Licensed Asbestos Building Inspector
- Licensed Air Sampling Professional
- Licensed Lead Risk Assessor
Specialties:
- Asbestos Assessment and Abatement
- Lead-Based Paint Assessment and Abatement
- Risk Assessment and Management
- Occupational Exposure Assessments
Experience Summary:
Guillermo Garcia co-founded GSG in 1992; leading the transformation of GSG from a small asbestos service company into a multi-faceted consulting firm specializing in engineering, environmental and construction management services. As CEO of the company, he has fostered growth through his leadership, vision, and long term strategic planning and encouraging participation in an expanding array of markets.
He has 25 years of experience in the industry and has worked extensively with the City of Chicago including the Chicago Public School (CPS) system, the Public Building Commission (PBC), and the Chicago Housing Authority (CHA). He is an active member of the Hispanic American Construction Industry Association and currently sits as the Executive Vice Chairman of the Illinois Hispanic Chamber of Commerce.
Arturo Saenz
Principal, Chief Operating Officer

Education:
- Bachelor of Science, Electrical Engineering, Northern Illinois University
Registrations:
- Certified AHERA Inspector
- Certified AHERA Management Planner
- Licensed Asbestos Project Manager
- Licensed Air Sampling Professional
- Certified Hazardous Waste Site Supervisor
- Licensed Lead Risk Assessor
Specialties:
- LEED Design
- Capital Development Programs
- Hazardous Building Materials
- Environmental Planning
Experience Summary:
As Chief Operating Officer, Mr. Saenz is responsible for designing, improving, and assuring system-wide implementation of the policies and procedures that allow GSG to efficiently deliver services. He has 18 years of experience in environmental engineering, business development, and strategic planning, and provides direction and structure for operating units within GSG. Mr. Saenz has led corporate, federal, state, and local government environmental programs including those owned and managed by the Federal Aviation Administration (FAA), Illinois Capital Development Board (CDB), Chicago Housing Authority (CHA), and Chicago Public School (CPS) system.
Ala E. Sassila, Ph.D., P.E.
Principal, Chief Engineer

Education:
- Ph.D., Civil Engineering, Illinois Institute of Technology
- Master of Science, Civil Engineering, Florida International University
- Bachelor of Science, Civil Engineering, Florida International University
Registrations:
- Professional Engineer – Illinois, Indiana, Wisconsin, Maryland, Pennsylvania, Florida, Georgia, Louisiana, Alabama, and South Carolina.
Specialties:
- Civil Design
- Geotechnical Infrastructure/Foundation Analysis
- Construction Program Management
- Illinois Site Remediation Program
Experience Summary:
Dr. Ala Sassila has 25 years of experience in environmental remediation, construction management and inspection, and geotechnical engineering. As Chief Engineering Officer, he leads GSG’s technical operations, analyzing the technical feasibility of projects, coordinating client requirements with technical and regulatory specifications, and making the final decisions upon technical matters.
Ala specializes in leading large multidisciplinary teams of engineers and scientists in the implementation of infrastructure management programs. His experience includes the Midway Airport Terminal Redevelopment Program, the Terminal 6 Building and Underground Utility Bank Reconstruction Program at O’Hare International Airport, Pavement and Toll Plaza Building Improvements for the Illinois State Toll Highway Authority, and obtaining “No Further Remediation” letters for more than 50 public building projects throughout Chicago.
Scott A. Letzel, P.G.
Environmental Assessment and Remediation Practice Lead
Manager of Drilling and Exploration Services

Education:
- Bachelor of Science, Geology, Northern Illinois University
Registrations:
- Professional Geologist – Illinois, Indiana
Specialties:
- Soil and Groundwater Remediation
- In-Situ Treatment Technologies
- Risk Assessment
- Subsurface Vapor Intrusion
- Geotechnical Investigations
Experience Summary:
Mr. Letzel is a Licensed Professional Geologist with more than 20 years of environmental assessment and remediation experience. His expertise covers the full range of remediation services including remedial technology selection, feasibility studies, pilot tests, and full-scale corrective actions. His practice is focused on developing creative and cost-effective remediation strategies to meet the objectives of project stakeholders including the property owners, regulatory agencies, potential developers, and the public. He has worked on properties contaminated with chlorinated solvents and petroleum products, including former Manufactured Gas Plant (MGP) sites, and has provided emergency response services for transportation accidents. He has extensive experience in using risk assessment methods to establish remediation objectives based on future land use – often resulting in significant construction cost savings. In addition to his environmental restoration experience, he has implemented a number of geotechnical investigation programs for infrastructure improvement including underground pipelines, flood control structures, levee improvements, harbor retaining walls, and earthen dams.
Jigar M. Shah, M.S., CIH, CSP
Industrial Hygiene Practice Lead

Education:
- Master of Science, Environmental Engineering, Illinois Institute of Technology
- Bachelor of Science, Civil Engineering, Gujarat University, India
Registrations:
- Board Certified Industrial Hygienist
- Licensed Industrial Hygienist
Specialties:
- Indoor Environmental Quality
- Construction / Community Air Quality
- Mold/Microbial Studies
- Asbestos and Lead Paint Management
- OSHA Compliance
- Drinking Water Quality Testing
- Forensic Investigations
Experience Summary:
Mr. Shah is a Board Certified and Licensed Industrial Hygienist and Safety Professional with 14 years of experience and is responsible for implementation of GSG’s industrial hygiene services. His practice focuses on the assessment of worker safety and personal protection, management of hazardous building materials during construction, and the development of administrative and engineering controls to eliminate unsafe working conditions and unacceptable public environmental impacts.
Jigar is highly experienced in the assessment and abatement of hazardous building materials including asbestos, lead-based paint, mold, radon, and mercury, as well as monitoring of community air quality and construction noise impacts. His services support maintaining regulatory compliance for planned infrastructure improvements as well as responding to employee and worker complaints and legal enforcement orders at operating facilities.
Robert W. Suda, M.S., P.G., CPESC
Water and Natural Resources Practice Lead

Education:
- Masters of Science, Environmental Science, Southern Illinois University
- Bachelor of Science, Geology, University of Illinois
Registrations:
- Professional Geologist – Illinois, Indiana
- Certified Professional in Erosion and Sediment Control
Specialties:
- Storm Water Management
- Groundwater Supply & Protection Studies
- Erosion & Sediment Control
- Natural Resources Conservation & Restoration
- Environmental Assessment and Remediation
Experience Summary:
Mr. Suda is a licensed professional geologist with 19 years domestic and international consulting engineering experience in environmental management, protection, and restoration. He is responsible for providing technical direction and oversight to GSG’s water and natural resources services.
Bob specializes in the protection of surface water resources and other environmental sensitive receptors during the site development and construction process. He also has extensive experience in groundwater resource protection and development including assessment of surface water and groundwater impacts due to industrial activities such as mining, petroleum refining, and electric power generation. His groundwater management expertise also includes remedial action programs including those at Superfund sites, active and former military bases/facilities, and waste disposal sites.
George Kougias, M.S., P.G.
Environmental Due Diligence Practice Lead

Education:
- Master of Science, Earth Science, Northeastern Illinois University
- Bachelor of Science, Geology, University of Illinois
Registrations:
- Professional Geologist – Illinois
- Certified Professional Geologist
- Licensed AHERA Inspector
- Licensed Lead Inspector
- Licensed Air Sampling Professional
Specialties:
- Phase I and Phase II ESAs
- Hazardous Building Material Inspections
- UST Removal and Closure
- Property Transactions and Redevelopment Planning
Experience Summary:
Mr. Kougias has 16 years of experience in managing a diverse range of environmental contaminant issues and hazardous building materials, and provides technical direction and oversight for GSG’s environmental assessment services. He has extensive experience conducting Phase I/II Environmental Due Diligence Assessments including Lead-Based Paint (LBP) and asbestos-containing material (ACM) inspections as well as working on projects in the Illinois EPA Site Remediation (SRP) and Leaking Underground Storage Tank (LUST) Programs. He is responsible for the development of a full-range of assessment planning documents including sampling plans, health and safety plans, and quality assurance/quality control (QA/QC) plans as well as those associated with the implementation of remedial actions such as remedial cost estimates, site management plans, closure plans, and bidding documents.
Robert J. Claussen, P.E.
Geotechnical Engineering Practice Lead

Education:
- Bachelor of Science, Civil Engineering, University of Illinois
- Bachelor of Science, Mathematics, Rockford College
Registrations:
- Professional Engineer – Illinois
Specialties:
- Geotechnical Engineering
- Construction Inspection
- Land Development Planning and Permitting
- Drainage Design
Experience Summary:
Mr. Claussen provides technical direction and oversight for GSG’s geotechnical engineering services, specializing in structure foundation analysis and soils-related construction inspection. His experience includes preparing geotechnical and soils analysis reports, scheduling and coordination of construction inspection services, monitoring work progress and conformance with project requirements, reviewing field inspection reports and material testing laboratory data. He has extensive experience in the field inspection of soil conditions, observation of proof-rolling activities, evaluation of foundation bearing soils, and performing various field tests to evaluate native and constructed soil conditions.
Professional Staff
Every member of GSG is a valued asset to the firm and key to our ongoing growth and success. Our dedicated team of engineers, scientists, designers, and technicians provides a diverse range of expertise in the engineering and construction fields. The firms ability to provide results is driven by the strong sense of pride and ownership in all elements of our work – a key element of our corporate culture. Our professional staff includes:
- Civil Engineers
- Environmental Engineers
- Environmental Scientists
- Geologists and Hydrogeologists
- Waste Management Professionals
- Industrial Hygienists
- Safety Specialists
- Regulatory Compliance Specialists
- Certified Asbestos and Lead Inspectors
- Designers and CADD Operators
- Construction Engineers and Inspectors
- Architects
- Estimators and Schedulers
- Engineering Technicians
- Administrative Professionals