Plugin to import Aperture librairies does not release the memory used by the librairy after the import is completed

Question

Let suppose I import a 30GB Aperture Library into LR which is on my HD. After the importation, if I send the imported library to the Trash and clear the Trash the disk space is not released by LR. So after a few importations I get the message that I do not have enough space on my HD to copy another library on the HD from an external drive which contains many Aperture libraries.

Answer 1

Casita17,  I recommend you evaluate ssprengel's questions and advice.  Please read the following below, as we don't want you to lose images!  I fear that you may be using a "referenced" library in Aperture, and this is the reason your disk space is not being released.  I would NOT RECOMMEND breaking your library into pieces for now.   You may very likely lose critical linkages, especially in albums.  If you have a number of Aperture libraries to begin with, then never mind.  Just be aware, Lightroom users generally recommend using only one lightroom catalog, which it sounds like you're doing.
Lets forget your system drive for now.  Do you have two times the disk space on your photos drive?  If not, do you have another drive laying around with as much space?  I recommend you make a backup before you continue.
I'm not quite sure what approach your are using, but I think the root cause of your dilemma exists because of how Aperture and Lightroom manage and store your images.  It may help to post what actions you take, step by step, and include the error messages.
You may already know some of these concepts, but lets leave no stone unturned.
First, Aperture uses "libraries", which contain all metadata and previews.  These images may be stored within the database (managed images), outside the database (referenced images), or a combination.  Can you apply a filter to your all photos selection, and tell us how many managed and references images you have?
Please read this for a better explanation:
http://www.lifeafterphotoshop.com/managed-vs-referenced-files-in-aperture/
Second, Lightroom's catalog is like an Aperture library.  Only ALL images are stored externally, "referenced" in Aperture parlance.
You should be able to create the Lightroom Catalog on any drive.  However, where you eventually store your images depends on what options you choose in the plugin when importing these images.
Any "managed" photos in Aperture WILL BE copied to the location you specify in the plugin.  Any "referenced" files MAY OR MAY NOT BE copied to the location.  They may be copied, or they they may remain in place, depending what options you select in the plugin.
Not sure I follow where you have your aperture library, images, and where you eventually want to store your Lightroom catalog, and where you want to store your lightroom images.  I'd suggest not breaking up your Aperture library.
If you are short on disk space, I suggest making a backup.  Then, select all photos and change them from managed to referenced, which will relocate the photos from within the library, to outside the library, preferably on the same drive.  Then, create a Lightroom catalog, wherever you have room.
Run the plugin and choose the option NOT to copy the files.  This way, it will leave them in place on your photo drive.  Some images may be copied to the lightroom masters destination any way, so you may want to choose another location on your photo drive in the plugin import options anyway.
When the migration finishes, you can delete the Aperture library, which will not remove all that much, and will not make much more space available.  And do NOT delete the image location you designated in Aperture, because you'll now be using it for Lightroom.  But this way, you'll be able to keep your space usage under control.
But KEEP your backup, even after the migration, JUST IN CASE!