Cornerstone Earth Group integrates geotechnical engineering, environmental services, engineering geology, and construction services into a single, client-focused team to facilitate cost-effective site selection, project design, and site development for commercial, residential, institutional, public works, and energy clients in California. Principals include Ron Helm, C. Barry Butler, Scott Fitinghoff, Pete Langtry, Danh Tran, Laura Knutson, and John Dye.