To provide energy to our customers APS converts raw materials into our final product – electricity. Conversion processes typically result in the generation of waste products and ours is no different. However, we are committed to efficiently extracting value from the resources that are necessary to provide our customers with safe and reliable energy. We maximize the use of our fuels and supplies, and work to not only eliminate or minimize waste where possible but also to responsibly manage the waste we generate.

Investment Recovery

By managing the disposal of obsolete and surplus property, equipment and materials, we are able to recover costs while reducing our environmental impact. Approximately 40 percent of the non-hazardous waste tracked through our Investment Recovery group is recycled. These efforts include diverting materials from landfills through specialized recycling streams (such as scrap metal and e-waste) as well as comingled, single-stream recycling of common materials. Waste is also diverted through the APS forestry program, including vegetation that is removed and mulched.

We continually look for new ways to reduce our environmental impact. In 2017, a program was implemented to recycle spent solar panels. We have found that for a variety of reasons solar panels may not operate for the expected lifetime and will need to be replaced thereby generating a waste stream. More than 16,000 solar panels were recycled during the year, representing nearly 450 tons of waste that was diverted from landfills.

Approximately $1.8 million was recovered from recycling and surplus asset sales in 2017. Many reusable materials were donated to non-profit organizations such as Habitat for Humanity, Treasures for Teachers and a charitable organization that supports the Phoenix Police Department’s canine unit. We also help recycle and recover resources in communities that lack adequate recycling services, such as Douglas, Globe and Wickenburg, Arizona.

APS Recycling Table

Hazardous Waste

APS has a hazardous waste goal to limit the generation of non-episodic hazardous waste to no more than a three-year average of 14.5 tons per year. This goal represents a 94% reduction from our 2001 baseline year. A three-year average is used for this target to smooth the hazardous waste generation curve consistent with major plant outages.

In 2017 we generated a total of about 92.5 tons of hazardous waste. However, the majority of this hazardous waste due to the cleaning of a fuel oil storage tank at the Yucca Power Plant, which resulted in a one-time episodic generation of 84 tons of hazardous waste. Disregarding the 2017episodic event, the 2017 hazardous waste generation was 8.5 tons and the three-year average generation was 5.9 tons, which is about 60 percent below our hazardous waste generation target.

Coal Combustion Residual Rule

In accordance with the EPA’s Coal Combustion Residual (CCR) rule, APS has installed monitoring wells around its coal ash impoundments. We have completed the required initial groundwater monitoring and we will continue to monitor under the provisions of the CCR rule. Compliance with the CCR requirements helps APS characterize the integrity of its impoundments and their effect on groundwater, if any. We have also completed a full assessment of our coal ash impoundments and determined that there are no underground conveyances that would allow the inadvertent discharge of coal ash.

Ash Reuse

APS manages the reuse of coal ash to help reduce our environmental footprint while adding to our bottom line. Coal ash is a waste stream resulting from the burning of coal, which is commonly landfilled. We sell much of our coal ash to concrete manufacturers, who use it as a direct substitute for cement in the production of their products. This reduces the amount of cement that otherwise would need to be produced, significantly reducing energy consumption and contributing to a reduction in greenhouse gas emissions.

The Cholla Power Plant sold approximately 85 percent of its total ash for reuse in 2017. Because of its remote location, the Four Corners Power Plant has a more limited market for ash reuse, selling about 42 percent in 2017. Collectively, between Cholla and Four Corners, APS generated 1,151,841 tons of coal ash in 2017 and sold 633,833 tons, representing 55 percent of the total amount produced. The amount of coal ash sold correlates to a reduction in carbon emissions of 380,299 metric tons in 2017.

Coal Ash Reuse Table

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 include air emissions from power plants or coal ash disposal. Our reporting facilities are the Four Corners Power Plant near Fruitland, New Mexico, and the Cholla Power Plant near Joseph City, Arizona.

The majority of these releases are captured by the plants’ pollution control equipment or contained within the coal ash by-product, which is either recycled for beneficial use or properly managed in coal ash surface impoundments and landfills.

Polychlorinated Biphenyls (PCB) Management

APS proactively identifies and manages PCB and PCB-contaminated equipment. We have been successful in reducing the amount of electrical equipment containing PCBs by targeting suspected equipment based on manufacturer names and serial numbers. The PCB status of our electrical equipment is tracked in an electronic database, which is available across the company. Between 2000 and 2017, APS removed 17,683 pieces of equipment from the distribution and substation systems, resulting in the disposal of more than 4 million pounds of PCB-containing material.


In 2017, APS completed the remediation of historic lampblack contamination that was buried at the site of a former manufactured gas plant. The site is located on Grant Street in downtown Phoenix and was owned by one of our predecessor companies, Central Arizona Light and Power Company. More than 60,000 tons of contaminated soil were removed and replaced with clean fill dirt, bringing the site up to residential soil remediation levels. The project was completed on time and more than $1.5 million under budget.

Nuclear Waste

Like all nuclear power plants, Palo Verde produces nuclear waste in the form of spent fuel, high-level waste and low-level waste such as used protective clothing, filters, resins and other contaminated items. We safely and securely store Palo Verde’s used fuel. Palo Verde has been aggressively moving spent fuel from spent fuel pools to dry cask storage. Dry cask storage is a safe, low-maintenance and effective interim storage method for spent fuel.

In addition to the on-site maintenance of spent fuel and high-level waste, Palo Verde manages its low-level waste by packaging the waste in proper containers and shipping the waste for disposal in “permitted disposal facilities.” Low-level radioactive waste numbers in the radioactive waste table represent waste that was shipped offsite, not what was generated for the year. Fluctuations in waste shipments are impacted by episodic events, legacy waste and what was disposed of in a given year.

Radioactive Waste Table

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