Van Gemeren, there are two answers to your question. The first one is cynical and goes this way. You have a cabinet minister in your riding who is lobbied to put a reserve unit in a government friendly area. It happens relatively quickly without much fuss or need for studies (I recall a naval reserve unit being formed this way several years ago in Quebec, but the details are lost to my memory). Such a unit may or may not be formed based on perceived needs of the Canadian Forces.
The second answer is fanciful, after decades of comprehensive study, including white papers, recommendations from military commanders, local notables, politicians of all stripes and repeated lobbying and arm-twisting a unit meeting the precise needs of the Canadian Forces and the local community is formed. An armouries is constructed that is well thought out with an indoor range, classrooms, messes and institutes, secure weapons storage, offices, plenty of storage space, possibly a museum, showers washrooms, repair facilities, QM and fenced vehicle park. It may even have a barracks room to sleep a platoon or larger unit.
Every city in Canada that is also occupied by a university has a reserve unit in close proximity, oh, except for Prince George, BC. Strategic considerations and geographic stability for staging and growth are included in the process as well as ready access to existing or possible training area would also be considered.