When Earth Day 2016 is celebrated on Saturday, April 23, a pair of local recycling centers are offering FREE guided tours at 10 a.m., 11:30 a.m. and 1 p.m. These inside looks are interesting for adults and useful for youngsters — perhaps for a future school project. The Boulder County Recycling Center (1901 63rd St., 720-564-2220) not only offers tours but also sells SoilSaver compost bins for $55 (cash or check) from 10 a.m. to 2 p.m. This price is roughly half that of the simplest backyard bins on the market. The city’s Center for Hard-to-Recycle Materials (CHaRM and ReSource Yard) together at 6400 Arapahoe Ave., 303-419-5418) shows how it recycles and repurposes a variety of materials.