Darren Yehl is the President and leader of Cornerstone Training Institute. He takes pride in his extensive background in environmental services and leveraged his leadership experience to create the vision of CTI Darren is committed to ensuring workers and community members are safe and trained appropriately to mitigate risk and environmental hazards. In his free time, he enjoys spending time with family and eating tacos at his favorite local Mexican cantinas.

Lynn Burlingham, the Office Manager of Cornerstone Training Institute, has devoted the latter half of her career to the environmental training industry, following her tenure at Kodak. She is responsible for managing CTI's class curriculum schedules and private trainings, and works closely with DOH, DOL, EPA, and OSHA. With 38 years of training experience and a background in operational efficiencies and management, Lynn is the central command of CTI. Her positive and joyful personality is unparalleled, making her a highly regarded figure at CTI.

Mark Gonzalez is a highly skilled Cornerstone trainer with extensive experience in the environmental, construction, and adult education industries spanning over 18 years. He is proficient in developing training programs that integrate real-world experiences and advanced multimedia technologies. Mark is also an accomplished Environmental Consultant with multiple certifications, including Asbestos Inspector Project Monitor, Lead Based Paint Inspector/Risk Assessor, Mold Inspector, and Authorized OSHA Instructor. In his leisure time, he enjoys entertaining his colleagues with his sharp wit and humor.