Styrofoam — referring generically to #6 expanded polystyrene foam — is a disposal headache. Extremely bulky, yet lightweight, it takes up space in the waste stream (and in landfills), but its removal doesn’t add much value to what is known as “diversion numbers.”   

In 1989, California Assembly Bill 939, known as the Integrated Waste Management Act, mandated reduction (or diversion) in waste disposal: jurisdictions were required to meet a 50 percent diversion goal by the year 2000. In 2011, Governor Jerry Brown signed AB 341, requiring a 75 percent reduction in disposable waste by 2020.

These goals are based on weight. So, for example, “green wastes” (lawn and...