Not that you asked...
I learned this the hard way, but it's been of good use since I did. Applies to just about all aspects of dealing with those pesky humans, in just about all circumstances, for strangers and friends and family alike! You cannot be upset that other people are not meeting your expectations if you never make your expectations known. You might feel you shouldn't have to, but that's not the way it works. Sounds like you've already done so regarding the trash, but you're going to need to do this often, all throughout your build.
Be polite and respectful, but be clear that you are not asking or negotiating, but rather explaining how things are going to go. You don't have to, and really shouldn't, address individual workers and subs, but rather make what you want known to the project manager and/or PB and allow them to manage their staff. Your absentee project manager issue is going to make that problematic, but that, too, can be one of the things you address. You can do this all in person, or in writing, ideally both: a conversation with a follow up email is a powerful thing, and can be very effective.
So the conversation, maybe a phone call, can be very simple:
"Hey Joe, I'm seeing a lot of garbage left around my yard. Please be sure that at the end of each day all refuge is picked up and removed from the job site. Thanks!"
Then a follow up email (the date stamp is a subliminal power trick):
September 30, 2020 - 9:10 AM
Joe, we spoke this morning by phone and we agreed that your workers would remove all trash at the end of each day.
Regards,
ALD
That's it. No complaining or emotions. Nothing about how much you hate seeing trash, or how it upsets you or the significant other. Just the facts, short and sweet, matter of fact: THIS IS HOW IT'S GOING TO BE. A clear indicator that YOU are in charge of your pool project.
If he pushes back, like "Well, we need a trash pile." then you push right back, with something reasonable, that you can both live with" "OK, understood, let's have that in one place, please, in the north east corner of the back yard." Or whatever. Be reasonable, but be clear.
And the simple matter of the garbage is a great way to set this stage. (Or use the next issue if the trash thing is handled already.) This is going to be a reoccurring theme throughout your build, and you need to make clear up front who is boss. There are going to be a lot of other topics and issues that you'll use this MO for, from tile defects to workmanship quality to where they park to overseeing dimensions to property damage to punch list, etc, etc. You use the same direct approach for each issue.
You can address the absentee project manager the same way:
"Hey Joe, I'm not seeing John the project manager nearly enough. Please make sure he checks in each day your subcontractors are onsite to supervise. I'm expecting him or you to be sure they're doing a quality job."
Then the follow up email. This, too, might get a push back. You decide on the fly how important each issue is to you, and how much you're going to insist. And as pointed out, you're holding the checkbook, so you've got the ultimate leverage.
Notice, you're not asking "Joe, can you make sure the trash is picked up?" You're telling: "Joe, please make sure the trash is picked up." It's not a small distinction.
The sooner you stand your ground on something seemingly inconsequential, the better. Then when there's something of real importance, like "Joe, the coping was not installed properly. Please meet me at the job site to discuss how this is going to be corrected. I'm available at the following times tomorrow..." you'll stand a better shot at an acceptable fix.
The only way the PB or his crew will take advantage of you is if you let them. And remember, they, and your pool, won't meet your expectations unless you make those expectations crystal clear.
Just a little un-asked-for advice!
Oh, a most important component: make a concerted effort to thank and praise the workers, the manager and the PB when things go well.
Everybody likes positive feedback. And nothing says that better than generous snacks and beverages handed out often. So go stock up on a pile of juices, sodas, Gatorade, snacks and treats: it'll be money well spent. And if all goes well, they won't leave any of those soda cans or snack wrappers behind!
Mr/Ms Nice when things are going well, B-on-wheels when not!