In a significant enforcement action, Denali Water Solutions LLC, a Russellville, Arkansas-based company specializing in biosolids management, has agreed to a $610,000 civil penalty for violations of the Clean Water Act (CWA) in Arizona and California. The U.S. Environmental Protection Agency (EPA) announced this settlement on November 12, 2024, highlighting concerns over the environmental and public health risks associated with the overapplication of biosolids.
Denali Water Solutions is a prominent player in the organic recycling industry, offering services that convert organic waste into fertilizers, renewable energy, and soil amendments. A core aspect of their operations involves the land application of biosolids—nutrient-rich organic materials derived from the treatment of domestic sewage. When applied appropriately, biosolids can enhance soil fertility and support sustainable agriculture. However, improper application poses significant environmental hazards.
The EPA’s investigation revealed that Denali had repeatedly applied biosolids to agricultural fields at rates exceeding the nitrogen requirements of the crops. This overapplication can lead to nitrogen leaching into groundwater or runoff into nearby surface waters, potentially causing eutrophication and other ecological disturbances. Such practices violate the CWA, which regulates the discharge of pollutants to protect water quality. The violations occurred at multiple sites in Arizona and California, where Denali’s operations failed to adhere to agronomic rates—the calculated amount of nutrients needed by crops—resulting in environmental contamination. The EPA’s enforcement underscores the necessity for strict compliance with biosolids application guidelines to safeguard environmental and public health.
In response to the violations, Denali Water Solutions LLC has agreed to a $610,000 civil penalty as part of a settlement with the U.S. Environmental Protection Agency (EPA). Beyond the financial penalty, Denali is required to cease land application activities in the affected regions of Arizona and California. Should the company seek to resume operations in these areas, it must implement specific soil sampling and agronomic rate calculation protocols to ensure compliance with environmental standards. The EPA estimates that these measures will prevent the excess application of approximately 5.8 million pounds of sewage sludge annually, thereby mitigating potential environmental harm.
Overapplication of biosolids can lead to several environmental and health risks. Excessive nitrogen from biosolids can leach into groundwater or run off into surface waters, contributing to nutrient pollution. This can result in eutrophication, a process that depletes oxygen in water bodies, harming aquatic life and disrupting ecosystems. Additionally, biosolids may contain contaminants such as heavy metals, pathogens, and organic pollutants. When applied inappropriately, these substances can accumulate in soils, potentially entering the food chain and posing risks to human health. A study published in Environmental Health highlights that biosolids serve as a sink for emerging pollutants, which can be toxic and persist in the environment, yet their fate after land application and their impacts on human health have not been well studied.
This enforcement action against Denali Water Solutions underscores the EPA’s commitment to regulating biosolids application to protect water quality and public health. The settlement serves as a precedent, emphasizing the necessity for companies involved in biosolids management to adhere strictly to environmental regulations. The EPA continues to monitor and enforce compliance with the Clean Water Act, aiming to prevent similar violations and promote sustainable practices in biosolids application. This case highlights the importance of proper management and oversight in the land application of biosolids to mitigate environmental risks and safeguard public health.
