Our History


H. “Dee” Diederich, RLS, founded Surveyors Group, Inc. in 1988 and retired in 2006. His entrepreneurial spirit, skill in his trade and personal fortitude made Surveyors Group, Inc. a success from humble beginnings. Now, after almost 12 years, Mr. Diedrich decided to come out of retirement as a key-consultant to SGI. He has been instrumental in our push to offer 3D Scanning and UAV technology.

Timothy G. Blair, PLS, and David M. Dosen, PE, purchased the company from Mr. Diederich in April of 2005.

In January of 2013, we promoted one of our most devoted employees, Richard O’Connor to take stake in partial ownership of SGI.


Mr. H. “Dee” Diederich founded Surveyors Group, Inc. from the humblest of beginnings. Prior to forming SGI, he was part of a large Civil Engineering and Land Surveying company here in the Sacramento region. He eventually decided to venture out on his own.

For 10 years, he had a modest office outside of Loomis, California. SGI finally had outgrown that office and moved to Sunrise Ave. in Roseville, across from The Old Spaghetti Factory, in 1999. There the company continued to grow, and Civil Engineering became an integral part of the business. This additional service helped free SGI from the constraints of the seasonal work which is part and parcel with Land Surveying, and also helped to establish the broader clientele that SGI enjoys today. SGI eventually outgrew that office as well, and moved to the larger, more modern digs where we are currently located off of Foothills Blvd. in Roseville.

As any business owner knows, a successful company becomes a living entity. Nurturing and educating employees, performing an essential aspect of a client’s project, building a reputation of Quality Service and producing a long list of completed projects creates a Footprint of Establishment. Now that Surveyors Group, Inc. has produced over 30 years worth of such projects, SGI can be truly proud of their Footprint of Establishment in this region.

Owners & Managers

Mr. Blair worked for Surveyors Group, Inc. for 13 of the 17 years of Mr. Diederich’s ownership. Starting from the bottom as a chainman, over the course of those years Mr. Blair advanced to Vice President and Survey Manager of the company. Mr. Diederich’s leadership, skills and entrepreneurial spirit were instilled in Mr. Blair, who has striven to follow in our founder’s footsteps. He has over 30 years of experience in the Land Surveying field.

Mr. Dosen joined the company in 2004 as a future partner with Mr. Blair for the anticipated ownership transition. He is a licensed California Professional Engineer with over 20 years of Engineering experience, working in both the public and private sectors. He has worked as an Engineer for various private companies, as well as the City of Roseville and the City of Vacaville Engineering Departments.

Mr. O’Connor joined the company in 2001 as a Chainman/Party Chief. He has worked his way up the ladder and has worn many hats within the company, from running the Survey crews, design work in the Civil Engineering department, and hands-on work in the field. Mr. O’Connor has over 20 years of service in this industry since beginning his career in New Zealand.

A History of Quality Service!