The other day as I was driving, I noticed someone lifting a manhole cover and emptying out a large container of fluid. Is this permitted?

NO. While the sewer might be a convenient place to discard fluids such as anti-freeze, oil, paint, or unused chemicals, it can also be the most dangerous. These items can be the cause of an explosive atmosphere being produced and MAJOR damage being the result. These items should be disposed of properly. Call the Centre County Solid Waste Authority for advice.