You can turn off mowing the lawn which will keep them on barf duty unless you have a giant flower garden in their work zone. It's pretty much necessary if you have a coaster with a moderate or higher puke value in the park.

Also don't forget that you can put bathrooms near the exit of an upchuck inducing ride to keep the paths a little cleaner.

would add a nice dynamic if their job performance was based on how much they were paid and if you could fire the underperformers.