Waste Trends

Nuclear Waste | Hazardous Waste | Investment Recovery | Polychlorinated Biphenyls (PCB) Management | Spills | Toxic Release Inventory

Nuclear Waste

Like all nuclear power plants, Palo Verde produces nuclear waste in the form of spent fuel, commonly referred to as high-level waste, along with low-level waste such as used protective clothing, filters and other contaminated items.

There are currently no options for disposal or reprocessing of high-level waste. Therefore, Palo Verde has been aggressively moving spent fuel from spent fuel pools to dry cask storage. Dry cask storage is safe, low-maintenance and effective interim storage of nuclear waste until the U.S. Department of Energy meets its responsibility to provide a permanent nuclear waste storage facility.

In addition to the on-site maintenance of high-level waste, Palo Verde manages its low-level water by packaging the water in proper containers and shipping the waste for disposal in permitted disposal facilities.

Hazardous Waste

APS has been aggressively reducing our hazardous waste for a number of years. We have reduced hazardous waste from 193 tons per year in 2003 to 5.3 tons in 2015.The trend is down, except when episodic events occur, such as the a fire that occurred at the Elden Substation. The Elden Substation (an energy storage unit) contained lithium batteries which caught fire on November 26, 2012. APS responded by remediating the area outside of the energy storage unit and secured the unit it was released for disposal. The site became an episodic large quantity generator during disposal of the batteries in 2014, which is why there is an increase in waste generation for that year. In 2015, this trend continued its downward trajectory. The majority of the hazardous waste generated and shipped was from Four Corners due to activities associated with the decommissioning of Units 1-3. A total of 3,838 lbs. of hazardous waste was shipped from Four Corners alone, and consisted mostly of lead-based paint abatement waste. In 2015, the Palo Verde Nuclear Generating Station generated less than 3,000 pounds of hazardous waste during the year. In prior years, a number of our facilities were large-quantity generators of hazardous waste. Our goal is to have all of our facilities be either small-quantity generators or conditionally exempt small-quantity generators of hazardous waste. All of our hazardous wastes are transported by permitted companies to EPA-permitted hazardous-waste disposal facilities located in the United States.

Investment Recovery

APS’s Investment Recovery group is a leader in corporate recycling and landfill reduction. In addition to the traditional role of asset sales, Investment Recovery plays an active role in sustainability. In 2015, APS recycled nearly 40 percent of waste that was tracked through Investment Recovery. Material is recycled through both specialized streams (such as scrap metal and E-waste) as well as comingled, single-stream recycling of common materials. In 2015, Investment Recovery worked to broaden its scope in quantifying waste and recycling streams in the company. We are now tracking waste diverted through the APS forestry program. This is done through capturing quantities of vegetation that are removed and are able to be mulched.

Polychlorinated Biphenyls (PCB) Management

For a number of years, APS has had an aggressive PCB management program in place to manage PCB and PCB-contaminated equipment. APS has been successful in reducing the use of PCBs in electrical equipment by targeting suspected equipment based on manufacturer and serial numbers. The PCB status of our electrical equipment is tracked in an electronic database, which is readily available across the company. Between 2000 and 2015, APS removed 17,374 pieces of equipment from our distribution and substation systems, resulting in the disposal of over 3.9 million pounds of PCB-containing material. APS continues to proactively identify and manage PCB-containing equipment.


The only reportable spill of hazardous materials in 2015 occurred at our Palo Verde Nuclear Generating Station, where approximately 3,500 gallons of 8 percent sodium hydroxide solution was accidently released. The spill was immediately addressed and none of the spilled material left the site boundaries or entered into the soil or groundwater.

Toxic Release Inventory

APS is required to report lawful releases of chemicals listed by the EPA under the federal Toxic Release Inventory (TRI) program. Our reportable releases under the TRI program primarily comprise air emissions from power plants or coal ash disposal. Our reporting facilities are the Four Corners Power Plant in Farmington, New Mexico, and the Cholla Power Plant in Joseph City, Arizona.

The majority of these releases are captured by pollution control equipment or are contained within the coal ash by-product which is either recycled for beneficial use or stored in coal ash surface impoundments and landfills. As APS continues to install new pollution control equipment and retire units, the quantity of TRI-reported releases will continue on a downward trend.