Backstory: Every time I help a friend do random construction work, we end up having to drop paint, drywall and other hazardous materials at a special dump. It's time consuming and annoying.
The Idea: A mobile collection service for hazardous materials.
Deep Dive: Customers would be able to signup for a door-dropoff date. You would have to coordinate a route to pick up the materials and dispose of them properly. At scale you would be able to hire a driver and optimize routes.
Validation: I'm not sure one person loves dropping off hazardous materials.
Monetization: You would charge per item type and weight if applicable. As you add materials you would have to figure out an appropriate cost to keep your margins in line with what customers will pay.