One thing about recession built homes is people watch every penny.
I've seen glass but never used it for fill until this week.
What I noticed from placing.
Pro's
1 It's cheap.
2 It's light. (A truck carry's a very full load)
3 It's free draining and unaffected by water.
4 It's 90% in a pile and compacts easily.
5 It bridges soft or muddy ground with ease.
6 It's a recycled product. "Green"
Con's
1 It refects light and is a little blinding and hot when sun hits it.
2 It binds in the tracks of a mini ex and can be difficult to move through.
(https://i404.photobucket.com/albums/pp128/diyfrank/work/glass.jpg)
You drain all them bottles?