A big component of President Obama’s inauguration was the effort on recycling, composting and sustainability.

Pritchard Sports and Entertainment Group of Crofton, Md., was in charge of “cleaning and greening” the event, according to a news release. That meant collecting waste and recycling from an estimated 600,000 to 800,000 people attending the Washington occasion. It involved mapping out locations for all the waste stations, which included compost and recycling bins and waste receptacles, and coordinating volunteers to work at each station. It also involved collecting manure from 164 horses on the parade route.

Because security was the top priority, all-translucent bags were used so any potential hazard could be seen, said David Mayer, director of development and sustainability for Pritchard. “We can’t use certain garbage containers on the parade route or near the president, due to bomb issues. We have to get our employees cleared by the Secret Service to work.”