GS & TJ - Great Service & a Thorough Job....
GS & TJ - Great Service & a Thorough Job....

Our Team

Our expert staff is committed to providing you with competent, compassionate and reliable service.

Leon Slack



Leon has been in the construction industry with a nonprofit organization that builds commercial size buildings for the past 30 years. During that time he served as a construction foreman and communication coordinator for 15 years. He developed software for the needs of the accounting department that have been in use for 13 years. He served on the committee that managed the organization for seven years. He managed personnel of about 1,500 volunteers in building and renovating 75 commercial size buildings. He developed a barcoded ID system that was in use for several years to keep track of the volunteers. He coordinated disaster relief efforts after the Katrina storm and a hurricane in Florida by organizing crews of volunteers to go down to assist unfortunate victims. He also traveled down himself to inspect homes and help unfortunate victims of the disaster


He is also a licensed Residential Inspector in the state of Illinois, a BPI Certified Building Analyst, an EPA Certified Lead RRP Renovator and a Chicago licensed Masonry contractor.


Leon has the desire to help our clients feel comfortable with their investment choices.  He has the personal knowledge to be of assistance and the contacts to put together an expert team to be of service to our clients.

Carlos Rivera

Senior Associate - Electrical Engineer


Mr. Rivera has been with Environmental Systems Design, Inc. for 41 years.  He is responsible for the Project Management, design and specifying of electrical systems and fire alarm systems.

Mr. Rivera’s extensive experience includes data centers, trading facilities (Critical Facility dual utility services, UPS and Generator systems), multi-floor commercial interiors projects and government projects

Electrical Systems: Due Diligence and Facility System evaluations

Energy Code evaluations and design for LEED electrical requirements

Kitchen electrical service and distribution systems

Special Lighting & Dimming control systems


Mr Rivera have been involved in the many commercial projects, including:

Citigroup,Chicago,Illinois - 300,000 sf (Plus all building Tenant Renovations)

William Blair,Chicago,Illinois - 250,000 sf (Plus all building Tenant Renovations)

ChaseTower, Bank One - 600,000 sf (Plus all building Tenant Renovations)

GATX Corporation, 222 West Adams Chicago,Illinois - 150,000 sf

Barton Incorporated, One South Dearborn,Chicago,Illinois - 90,000 sf

And many many more...


Mr. Rivera has a lot of experience in commercial property design and inspections.


Contact Information

GS & TJ Services Inc.

Box 201455
Chicago, IL 60620


Phone: 773 234-4785

Fax:    773-584-0904


Or use our contact form.

Office Hours

We are open during the following hours:

Mon - Tues - Thurs - Fri

7:00 AM to 7:00 PM



7:00 AM to 4:30 PM



1:00 PM to 7:00 PM


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