It's pretty mixed in with chipped leaves and doesn't mat.

It would take a very, very large quantity of used coffee grounds on the surface of the soil to make that hydrophobic, water repelling. While to some what the average person generates in used coffee grounds may seem like a lot that quantity probably would not be enough to do that.

Agreed. You're probably only in danger if you're collecting bags and bags of the stuff from coffee shops and putting it directly on the ground in thick layers.

UCG is not my concern.

Maybe I should start a new acronym - UEG. Used Espresso Grounds. This is a bad analogy, but one that comes to mind. Kinda like using a shop vac to vacuum drywall dust. The fine particulate clogs the filter quite easily. Maybe I need to do a controlled test. A clear vessel - some soil. Dump about a dozen espresso pucks in the middle. Water ontop of the espresso grounds. See what the behaviour of the water goes.

What led me to this was I was just dumping on my grounds ontop of this spot that was exposed - root zone where it was not mulched. In looking at the top, aka, the UEG not incorporated into the soil, if too much overtime, i was thinking is it possible to form a ~crust~

There is no difference between the two. 95% of what you get from a Starbucks or other coffee shop recycling their waste will be espresso pucks. They function in the same way as any used coffee waste will. And if allowed to dry out, they will be just as crusty or as hydrophobic on the surface. It is typically recommended to work them lightly into the soil to avoid this and gain the maximum benefit. And crumble them first!!

Same as gardengal... all the UCG that I've gotten over the years from Starbucks are their espresso pucks that you have to break up. I've never received ground coffee that you would find in a drip filter from them. One other coffee shop I would also collect from gave you both espresso pucks and regular grounds (filters included).

I found that if you put them down even at a 1/4 to 1/2 inch… they would crust up on the soil. As noted before… just barely scratching them into the surface of the soil… or just ruffing up any mulch you have down below the UCG will stop the crust from forming all together.

You guys are lucky if you have source for bulk grounds easily. ,There are like 4 SB within a 5 minute drive N/S/E/W. 3 don't recycle used grounds. The last one, I've only gotten grounds there like twice when I asked, and then it stopped when the manager told them to stop. Each time, it was a bagful of drip coarse ground. I get it. It's more work for them to stop and dispose of grounds seperately than chucking it all in the trash,

Was the older run about Starbucks not collecting the grounds... don't know if that will help. Managers do change.. so you might get someone else that would be open to collecting them. Many times the employees seemed like they preferred when people would get the grounds since they don't have to haul a heavy bag out to the trash every day... and since they aren't added them to the regular trash... the regular trash can isn't so heavy too.

http://forums2.gardenweb.com/discussions/1610286/starbucks-wont-save-grounds