Trapper Creek is a scenic area of Alaska known for its relationship to Denali State Park, so it's no surprise that you can find a convenient local dump station that caters to the many campers that come through the area. There's plenty of local flora and fauna to experience in the area, but the most popular tourist activity in the area is to take the Denali gold tour.
Dump stations have a drain cap that covers the sewer and drain outlet. You need to close the valve on the tank, take the cap off the sewer and push the hose from your tank into the outlet. Once you turn the valve, the tank will empty the blackwater.
You should empty the tank when it reaches 2/3 capacity. If it goes any higher, it can overflow.
Dump stations generally charge users for their services. Some campground stations offer this service for free if you spend the night there.
A RV dump station is a facility that lets you empty your holding tanks without getting your hands dirty. It also uses sanitary methods to dispose of the waste.