Aerial view of <a href="https://en.wikipedia.org/wiki/Ridgway,_Pennsylvania" class="extiw" title="w:Ridgway, Pennsylvania">Ridgway, Pennsylvania</a> Waste Water Treatment Facility.
U.S. EPA
U.S. Environmental Protection Agency (EPA), Philadelphia, PA.<a rel="nofollow" class="external text" href="https://blog.epa.gov/blog/2013/09/how-3-wastewater-treatment-facilities-saved-69000year-in-energy-costs/">"How 3 Wastewater Treatment Facilities saved $69,000/year in Energy Costs."</a> <i>EPA's Healthy Waters in the Mid-Atlantic.</i>