Most environmental projects with a field component have an office-based project manager (PM), who works out the budget and schedule, deals with the client, and bargains with the other managers for appropriate personnel.
Then the field crew goes to work. The crew has a dedicated field team lead, who's responsible for getting the work done and communicating any issues/changes to the PM, who will notify other stakeholders (including the client) and adjust the overall project accordingly.
If you're a PM and your field crew is working outrageous hours, you need to be available for those hours. You may not need to be in the office, but you need to be on-call. Sure, it sucks to be chained to your phone in the evening or get rousted out of bed early in the morning, but the field crew doing your work is out there in the (potentially lousy) weather, doing physical and possibly stressful work.
Also, if the crew comes back from working long hours in the field and needs to spend another several hours in the office processing and shipping samples, and the PM is going to spend the rest of the afternoon at a golf tournament, the PM shouldn't be surprised if the field crew is a little... testy.