You have two options I can think of:
1 - Limit depth using Location Filters
Using a Location Filter you can limit the depth based on the number of back slashes in the path, e.g. to only search folders at the second depth we add a regular expression to ignore paths with four or more back slashes, e.g.
Look In: M:\Corporate;-:regex:(.*\\){4,}
So this would search paths with up to three back slashes:
M:\Corporate\Facility1\
M:\Corporate\Facility2\
M:\Corporate\Other\
etc.
but not four back slashes:
M:\Corporate\Facility1\2010\
etc.
2 - Regular expression in Look In field
Alternatively, you could simply search using a regular expression on the Look In field, e.g.
Look In: M:\Corporate\Facility.*
Subfolders: OFF
Expression type: Regular Expression