top of page

Cornerstone Training Institute  is a premier provider of cutting edge, and innovative training, consulting, and management services. We have long been recognized as a benchmark for quality integrity and dependability.   As a tried and true provider of professional training, we offer you the very best in professional development training and customized training solutions. Our unrivaled experience and expertise combined with our dedicated individual service ensures that you benefit from consistent training and development at every level of your organization and for whatever needs.

Your partner for 

Asbestos, Lead, and OSHA Compliance 


Darren Yehl is Cornerstone Training Institute’s President and fearless leader. Leading the company as it builds new digital training platforms and curriculum that empower and educate companies and their employees, Darren takes pride in his extensive environmental services background. Following sixteen successful years of leading LeChase Construction’s Asbestos and Environmental Remediation team, Darren leveraged his two decades of leadership experience in environmental services to create the vision of CTI. Possessing a deep commitment to ensuring workers and community members are safe and trained appropriately to mitigate risk and environmental hazards, Darren can also be found conducting trainings and leading by example. Don’t be surprised if you see Darren out on the water unwinding with family or enjoying tacos at your local Mexican cantina!

Darren Yehl



Cornerstone training Institute’s Office Manager Lynn Burlingham, formerly of Kodak, has invested the latter half of her career in the environmental training Industry.  Consistently working with the DOH, DOL, EPA, and OSHA, Lynn manages CTI class curriculum schedules and private trainings. While working with Cornerstone you are guaranteed to meet Lyn as she runs everything from customer newsletters that keep everyone up to date on the ever changing requirements of the industry to the first smile you see upon entering our offices.  With 38 years of training experience and an extensive background in operational efficiencies and management, Lynn is the central command of CTI. She has a background in Lithography and a diploma from RIT for Public Relations Graphic Communications. Lynn’s positive and joyful personality is unmatched making her a pretty big fan favorite at CTI.

Lynn Burlingham

Office Manager


Randy Holden is the Operations Manager for both Cornerstone Training Institute and Yehl Environmental. Working closely to develop new training programs and protocols with CTI’s accredited trainers, Randy provides consistent advisement and expertise to keep CTI agile and meet client’s needs. Currently he volunteers in a wide variety of capacities and holds numerous licenses and certifications; including, EPA Asbestos Building Inspector, Supervisor, Project Designer, and NYS Article 32 Mold Assessor. Randy is approved by the N.Y S Department of Health and United States Environmental Protection Agency in multiple teaching accreditations and is approved to teach the Model accreditation program asbestos classes. He also teaches the HazWoper curriculums and is an Authorized O.S.H.A, Occupational Safety and Health Administration Outreach instructor throughout the United States. A Finger Lakes native, Randy enjoys time with family experiencing everything the Finger Lakes has to offer.

Randall Holden

Operations Manager


Shelly Pauley is Cornerstone Training Institute’s Account and Client Manager. With her outstanding communication skills, Shelly looks after and manages all aspects of accounts including accounts payables and receivables. Born and raised in Iowa, Shelly came to New York just a few short years ago for its long tropical summer months of course!  Shelly has a diverse background in administration, bookkeeping and accounting which she continues to leverage to best support customers who depend on CTI for all their trainings needs. Shelly is passionate about her career, family, and the San Francisco 49ers!

Shelly Pauley

Accounts & Clients Manager

    QUALITY                    INTEGRITY                         DEPENDABILITY


Jean Putthasy is CTI’s Administrative Assistant. Matching students and businesses with their class needs, Jean welcomes each student to ensure they have the resources needed to succeed at Cornerstone Training Institute. With a background in legal, litigation and accounting for over 15 years, Jean possesses outstanding customer service which leads to building vital partnerships at Cornerstone Training Institute and Yehl Environmental. An avid gardener, Jean is also the resident chef at CTI and makes the best Pho in town!

Jean Putthasy

Administrative Assistant 


 When it comes to tailored training, we can even work with you to define your training needs and deliver customized training solutions to meet your exact learning requirements. Plus, with expert trainers that are experienced practitioners in their fields, our training moves beyond theory, giving you valuable real-world insights.

We are truly committed to you; our valued client

The Cornerstone


It's all about you!


Mark Gonzalez, esteemed Cornerstone trainer, is an experienced mentor with a demonstrated history of working in the environmental, construction, and adult education industries for over 18 years. Skilled in training program development, with an emphasis on applying real world experiences into comprehensive teaching modalities, Mark strives to incorporate the latest in multimedia and virtual/ augmented reality technologies.  Embracing the synergy of today’s tech and effective adult training principles, Mark spearheaded Cornerstone’s Online E-learning division and revolutionized the direction CTI Online is moving in. Mark is also an experienced Environmental Consultant who maintains certifications as an Asbestos Inspector, Project Monitor, Lead Based Paint Inspector/Risk Assessor, Mold Inspector and is an Authorized OSHA Outreach Instructor.

When Mark isn’t behind the camera or in front of a class he is keeping the office and friends entertained while perfecting his witty humor.

Mark A, Gonzalez

E-learning/ Online  Training Director


One of Cornerstone Training Institute’s valuable trainers, Mike is an experienced network specialist and safety trainer driven by a desire to help others. If you have been in any of Mike’s classes, you know he takes pride in the skills he teaches and work he does at Cornerstone. In addition to his primary role as a technical specialist, Michael also teaches several other classes including OSHA 10 Hour/30 Hour Safety Training, and Disinfection Worker/Manager Training. He is a certified network technician, an authorized OSHA outreach trainer, and a licensed asbestos building inspector. Michael’s dedication to Cornerstone and his resiliency has help modernize CTI’s training platforms offered. He has been instrumental in our ability to continue to provide leading industry instruction.

Michael    Gonzalez

Technical /Production  Dept


Cornerstone Training Institute’s Event coordinator Jennifer Roberts supports CTI in a number of roles. From vendor coordination to on-site team events and travel management, Jenn is always calm and composed while thinking two steps ahead, she is prepared to implement Plan B or C if needed. With a keen understanding of technical matters, she has the ability to figure out complex roadblocks and is an expert working with multiple departments to achieve the common goal. Combining analytical and creative thinking, she sincerely cares about delivering high quality work every time. With more than a decade of travel, event and meeting planning experience, Jennifer enjoys learning on the job as well as meeting new people within the industry.  An avid traveler, water and beach lover, Jen enjoys spending time with her family on the lake and learning to sail!

Jennifer Roberts

Events Planner 

















bottom of page