Native of Quebec City, LCol Desjardins joined the Army Cadets and the Reserve before enrolling in the Canadian Forces in 1975. In 1980, he obtained a bachelor's degree in mechanical engineering from the Royal Military College (RMC) of Canada in Kingston.
After completing his military engineering training at CFB Chilliwack in February 1981, LCol Desjardins was posted to 1 Construction Engineering Unit (1 CEU). As a project officer, he coordinated the implementation, study or design of a number of major projects in the Canadian North and Bermuda.
In 1984, LCol Desjardins was posted to 5eme régiment du génie de combat at Valcartier, Québec. In 1986, LCol Desjardins was posted to CFS Mont-Apica, a radar Station, where he took charge of the Construction Engineering section. In 1988, LCol Desjardins undertook a master's program at RMC Kingston in mechanical engineering. Upon graduation in 1990, he returned to 1 CEU where he conducted numerous studies and construction projects in Canada and abroad. During this period, he was seconded to the United Nations and deployed to Western Sahara as the UN engineer to initiate camp construction for the peacekeeping forces.
Promoted to Major in 1992, he was posted to Air Command HQ as Staff Officer Airfield Engineering Operations. As such, LCol Desjardins was responsible for the development of the new airfield engineering structure, organization and training to ensure its ability to deploy anywhere in the world. He was also responsible for the development and coordination of the disaster response for the Caribbean's on behalf of Canadian Armed Forces. This annual commitment was activated in September 1992 where LCol Desjardins coordinated the Canadian Engineering operations as part of the Combined US Task Force in Miami Florida following Hurricane Andrew. He is awarded the Air Force Commander's Commendation for his contribution. In 1994, he was appointed for a year as the Senior Staff Engineer for the United Nations Mission in Haiti. In this capacity, he developed the concept and implemented the military engineering support and construction plan for the 6000 strong Force. LCol Desjardins was awarded the Chief of Defence Staff and the US Army commendations for his exemplary service in this mission.
In 1996, he was transferred to 17 Wing Winnipeg to serve as the Wing Construction Engineering Officer for three years. Upon completion of the one-year course at Canadian Forces Command and Staff College and promotion to his present rank in 2000, he served for two years as the Project Director for the development of the National Military Support Capability at the National Defence Headquarters in Ottawa. Remaining at the National headquarters, LCol Desjardins joined ADM(IE) in 2002 and took over the responsibility of the Canadian Forces Fire Marshal three years later while remaining in DGME he joined DCPEP as the director. He is currently on assignment as Acting DRAP since April 2007.