Surveying the bins after closing, hundreds of disposable cups were found by night-market organizers.1 For three weekends, they counted the bags of cup waste and noted which stalls sold the most drinks. The following season, the organizers introduced a shared supply of durable cups. They selected two cup sizes that fit the vendors' existing lids and drink carriers. They expected washing the cups to be more efficient as throwing them away2 after every drink.
The cup depot which occupies a converted food truck stores3 clean cups and collects used ones. Shelves inside the truck separate sanitized cups from returns awaiting inspection. Participating vendors were totally into this thing4 after learning that the depot would handle all washing. Customers pay a small deposit when ordering a drink and receive it back when returning the cup. A numbered token links each deposit to one borrowed cup. At the return window, a volunteer scans the token, checks the cup for cracks, and releases the deposit. Another volunteer rinses the cup before placing it in a high-temperature washer. Clean cups dry on covered racks and return to vendors in labeled crates. Within two weekends, most customers had embraced5 the routine.
At first, nearly all borrowed cups came back before the market closed. By the fifth week, however, the return rate had declined. Depot records showed that many unreturned tokens had been issued near two exits farthest from the return window. Consequently,6 organizers posted reminder signs beside trash and recycling bins. Each sign displayed the deposit amount and an arrow toward the depot, using the same token symbol printed on vendor menus. The new signs worked.7 Each of the three washing shifts are8 staffed by two volunteers, allowing returned cups to reenter circulation quickly. A full wash cycle takes eight minutes, and the crew records the number of cups rejected for damage after each cycle.
The system now serves eighteen vendors without requiring each stall to buy a separate set of cups. The cup depot is housed inside a converted food truck.9