Mirriam-Webster defines greenwashing as "expressions of environmentalist concerns especially as a cover for products, policies, or activities."

A Class III composting facility is not what you think of when you hear the word "compost."

A Primer on the Greenwashing of Sewage Wastes Pollution

Nancy V. Raine, Sierra Club Grassroots Network Wastewater Residuals Core Team Member


Publicly Owned Sewage Treatment Works (POTWs), such as the Boulder Water Treatment Plant, are designed to receive vast volumes of human biological, non-industrial waste from sewers and to extract “clean water” from the sewer stream. This water is released back into drinking water sources. 


A loophole in the 1972 Clean Water Act (CWA), however, allows large industrial facilities to discharge wastewater that contains hazardous wastes -- toxic chemicals, radioactive materials, and infectious wastes -- into these same sewers. Another loophole in the 1976 Resource Conservation and Recovery Act (RCRA) specifically excludes municipal sewage from being regulated as a hazardous waste. These loopholes set the stage for nearly a half century of recycling complex industrial poisons into our food and water through the use of toxic sewage sludge as “fertilizer” and “soil amendments.” 


How could this have happened?


Sewage sludge is the “leftover” from the treatment of wastewater. The cleaner the recycled water, the more toxic the residual sludge. This sludge, which is a liability for wastewater treatment plants, undergoes various treatments to reduce biological pathogens and malodor. Heavy metals and chemical wastes, however, remain after treatment and are concentrated in the sludge. Of the thousands of pollutants in sewage sludge, the Environmental Protection Agency (EPA) only regulates 9 out of 23 heavy metals.


Sewage sludge is an unpredictable toxic mix of heavy metals, PCBs, PFAS, dioxins, many synthetic chemicals and industrial solvents, micro-fibers, radioactive waste, medicines, pesticides, asbestos, petroleum byproducts, microplastics and pathogens. To date the EPA has identified a mere 352 pollutants of the thousands in sewage sludge, 62 of which have been classified as hazardous by other federal programs.


What to do with this toxic sludge has always been a problem. It was dumped into the ocean until 1988 when Congress passed the Ocean Dumping Ban Act because of the severe environmental damage ocean disposal created. In response, the EPA raised the legal limits of acceptable exposure to many contaminants so that most of the nation’s sludge could be classified as “clean.” Eyeing agricultural land, and ever mindful of the nitrogen and phosphorus content in human feces, the agency redefined sewage sludge as a “beneficial fertilizer.” States, including Colorado, followed the federal lead on how to solve the sewage sludge disposal problem. 


To gain public acceptance, the EPA sponsored an elaborate public relations program in 1993 to promote and market sewage sludge as “fertilizer,” renaming it “biosolids” and describing land disposal as “beneficial use.” In close cooperation with the EPA, a special interest group with regional affiliates, The Water Environment Foundation (WEF), began promoting “biosolids” as an “organic” soil amendment, compost, and fertilizer. Under various flags -- Zero Waste, Sustainability, and Carbon Sequestration – WEF’s entire focus is the manipulation of public opinion by using sophisticated PR crisis management techniques that hide the truth in plain sight. Over the last 50 years, a multi-billion-dollar waste management industry has formed around this elaborate liability transfer and greenwashing scheme.


Boulder’s treatment plant produces about 1,5000 Dry Metric Tons (DMT) or roughly 3.3 million pounds of sewage sludge per year. The word “Dry” indicates that the number only includes the weight of the sludge. It does not include the weight of the water/moisture that is in the sludge when it is hauled away from the plant and land applied. Boulder's biosolids are generally hauled as a "dewatered" biosolid, which means the biosolids will be around 17 to 26 percent solids. Boulder contracts with a sludge hauling and reuse specialist (Denali Water Solutions) to transport, handle, and land apply its biosolids on agricultural properties, primarily in east Adams County. 


In 2019, 90% of Colorado’s sewage sludge was disposed of on land -- that’s 68,608 Dry Metric Tons or 137,216,000 pounds of toxic waste disposed of on agricultural fields or composed and distributed to the public in compost. There are around 1,100 sites that are currently active in the state and another 1,400 sites that are inactive, but still authorized for sludge disposal. 


Approximately 15-20% of the total biosolids generated in Colorado each year are used in composting. A1 Organics (Eaton, Keenesburg, Englewood, and Commerce City), which was identified on Boulder County’s website as the prospective operator of the proposed composting facility on the Rainbow Nursery site and Renewable Fiber (Denver and Fort Lupton) are composting companies that accept biosolids as a feedstock, among others throughout Colorado. Only about 10% of this toxic waste was disposed of in landfills or surface disposal sites in 2019. 


The National Sierra Club has long rejected this elaborate greenwashing scheme that results in many toxic pollutants contaminating open space, agricultural soils, ground water and streams. Specifically, the national Sierra Club opposes the use of contaminated toxics and/or pathogen-containing sewage wastes as a compost ingredient and the application of municipal sewage sludge/biosolids as a fertilizer. (Compost Policy, Sewage Sludge Policy and  Agriculture and Food.)


For more information, visit the Sierra Club’s Grassroots Network Wastewater Residuals Team web page: and download its Sewage Wastewater Residuals Fact Sheet: