Bill, there are just some of those places out there that are like that. I've been to parks that had BIG signs posted everywhere that said "NO ALCOHOLIC BEVERAGES ALLOWED" that had so many steel beercaps on/in the ground that they were almost like gravel footing. Places like that are impossible to detect in with a large concentric coil. A DD of any size will be an improvement, and a smaller DD will do best. Beyond that, it's all patience, determination, and luck.
At sites like that, I personally don't care which machine I'm runnng, I've got a DD on it. And I DISC the junk, but pay attention to the null. If it signals a nulled blip I pay little attention. But if it's a larger object being nulled, I'll work my way around it's perimeter swinging the edge of the search pattern (not the tip of it) from outside to the null, so if there is a good target that can be seen anywhere around it before hitting the null, I'll find it. If you just keep working past it (instead of going all the way around it) you risk the coil registering the null before it gets to the good object, and you'll never know it's there.
As easily as good targets can be masked by minimal junk, there is often a lot of good stuff to be found at those sites. The problem is getting past the trash. In some cases, they can be sorted out of the trash with a coil that separates well. But in other cases, the only way to score big is to get the trash out of the way. It's a thankless tedious job, but can be rewarding if you're persistant.
I usually run my 705 in AM most places, but sites like that will have you ready for the nuthouse or so mentally fatigued after a short while, that realisticly a little DISC can save your sanity.
