If you’ve experienced the Philadelphia Marathon in the past few years, either as a participant or spectator, you probably think first of the crowds: one of the largest marathons in the country, the Philadelphia Marathon draws nearly 100,000 people each year. But with all those people comes a lot of waste: thousands of pounds of water bottles, banana peels, and energy bar wrappers.

For the past four years, the Philadelphia Marathon has worked with Waste Watchers, a partnership between the Office of Sustainability and the Mayor’s Office of Civic Engagement and Volunteer Service, to divert much of that waste away from the landfill. At the beginning and end of the Marathon and at water stops along the way, hundreds of Waste Watchers volunteers help event-goers sort their trash, recycling, and compost into the right containers.

The result? Each year, Waste Watchers helps the Marathon divert more than nine tons of waste from the landfill. Had it been thrown away, this waste would have contributed to ground pollution and greenhouse gas emissions. Instead, it is re-purposed into recycled goods and soil amendments.

In 2015 Waste Watchers helped the Marathon reach 90 percent waste diversion, a new record and the widely-accepted definition of “zero waste.” It’s an amazing achievement, and it wouldn’t have been possible without the commitment of Philadelphians to sustainability and volunteer service.