Re Justin and Glass Factory Brownfield conditions.
Is there contamination of anything other than “broken glass” and in what condition would that contaminate be? .. Glass is just another form of sand, I wonder if you could tumble the contaminated ground in something like what they tumble new bricks to make them look old. Smooth off the edges, maybe reduce the size by throwing in some gravel with the glass. Then taking the now not sharp small glass pieces and tilling it deep into the soil. Just a thought.
If it’s more than just glass shards then you might either have to remove the contaminant or contain it within an impervious liner envelope, not just cap it. Your state must have a Brownfields program which could refer you to other case studies for your reference. Check with them. Maybe they have a use for the contaminated soil? One never knows.