APS has maintained a long commitment to pollution prevention and waste minimization. More than 30 years ago, APS began a campaign to identify and minimize all forms of waste material including solid, universal and hazardous waste. The campaign focused on reducing waste materials, using product substitution to eliminate hazardous waste and recycling waste where possible. This effort dramatically reduced the amount of waste generated through our company and led us to create a waste reduction metric that continues today. 

Following the waste reduction campaign, APS developed Pollution Prevention (P2) Plans for our power plants. These P2 plans are implemented and maintained by the company and some are filed with the state environmental quality agency, as required. For nearly 10 years we have enhanced our pollution prevention and waste minimization commitment through our ISO 14001 certified All our operating areas, including both power plants and transmission and distribution service centers, maintain an ISO 14001 certified Environmental Management System (EMS) that includes a company policy to reduce our environmental footprint and prevent pollution.

Waste Recycling and Investment Recovery

By managing the disposal of obsolete and surplus property, equipment and materials, we are able to recover costs while reducing our waste and environmental impact. Approximately 54 percent of the non-hazardous waste tracked through our Investment Recovery group was recycled last year, a 14-percent increase from 2017. 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.

The Investment Recovery department is continually looking for new ways to reduce our environmental impact. In 2018, a program with a “zero waste” goal was tested. The Investment Recovery department partnered with several of our recycling vendors to achieve this goal on a large transmission project. Investment Recovery helps smaller Arizona communities that lack adequate recycling services, such as Douglas, Globe and Wickenburg, recycle and recover resources. In 2019, we plan to explore opportunities for increased redeployment of APS equipment internally and an effort to send material out to be refurbished and resold. This opportunity will extend the life of material to new users and APS as well as keep that material out of a landfill.

Approximately $2.2 million was recovered from recycling and surplus asset sales in 2018. Many reusable materials were also donated to nonprofit organizations such as Goodwill of Arizona and Treasures for Teachers. Additionally, Investment Recovery is currently assisting with a special donation for the Gila Bend Firing Range for the U.S. Air Force.

Investment Recovery Recycling Table

Hazardous Waste

APS has a commitment to reduce hazardous waste with a goal of limiting the generation of non-episodic hazardous waste to no more than 14.5 tons per year, based on a three-year average. This goal represents a 94-percent 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.

The 2018 hazardous waste generation was 7 tons and the three-year average generation was 8 tons, which is about 45 percent below our hazardous waste generation target. We had one episodic event resulting in hazardous waste in 2018, from the replacement of a Selective Catalytic Reduction material at Sundance Power Plant creating 16 tons of hazardous waste.

Hazardous Waste Data Table

Toxic Release Inventory

APS is required to report releases of chemicals listed in the federal Toxic Release Inventory (TRI) program to the EPA. Our reportable releases under the TRI program primarily include air emissions from power plants or coal ash disposal. APS’s TRI releases for 2017 were down 77 percent from 2007, primarily due to significant investments made in environmental controls for our power plants and decreased coal generation. Specifically, there was a 90 percent reduction in air releases from 2007 to 2017 due to our actions to reduce air emissions. 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. Our reporting facilities are the Four Corners Power Plant near Fruitland, New Mexico, and the Cholla Power Plant near Joseph City, Arizona.

TRI Data Table

Polychlorinated Biphenyls (PCB) Management

APS proactively identifies and manages PCB and PCB-contaminated equipment. We have successfully reduced 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. From 2001-2017, APS removed 17,532 pieces of equipment from the distribution and substation systems, resulting in the disposal of more than 4 million pounds of PCB-containing material. 2018 data will be updated when available. 

Coal Ash Management

When coal is burned to produce electricity, it generates several by-products. One of these by-products is coal combustion residuals (CCR), generically referred to as “coal ash.” Coal ash is mainly made up of rocks, minerals and other non-combustible, natural materials mixed in with the coal when it is mined from the earth. Our two coal combustion facilities consume about 6 million tons of coal a year, yielding approximately 1.2 million tons of coal combustion residuals annually; much of this residual can be recycled and reused in manufacturing commercial products. Each coal-fueled plant is unique in the amount and type of ash produced and how it is reused or disposed.

APS manages the reuse of coal ash to help reduce our environmental footprint while adding to our bottom line. To keep our coal ash from being landfilled, we sell much of our coal ash to concrete manufacturers, who use it as an essential component 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 decrease in greenhouse gas emissions. 

Collectively, between Four Corners and Cholla, APS generated 1,164,922 tons of coal ash in 2018 and sold 668,799 tons, representing 57 percent of the total amount produced. The amount of coal ash sold correlates to a reduction in carbon emissions of 401,279 metric tons in 2018, the equivalent to removing 85,000 cars from the road for a year. The market for selling coal ash is limited for Four Corners because of its remote location, thus the plant sells a lower percentage of its coal ash than Cholla does. 

It should be noted that APS will cease combustion of coal at the Cholla facility by mid-2025 and has immediate plans to reduce the overall number of regulated coal ash impoundments at its Cholla and Four Corners facilities starting in 2019 as described below. In the interim, APS is committed to beneficially reusing coal ash residuals to the extent practical and to reducing its overall coal ash management footprint.

APS has installed monitoring wells around its coal ash impoundments and continues to monitor groundwater quality in accordance with the CCR rule. Additionally, APS is undertaking engineering projects at Cholla and Four Corners designed to minimize the impacts associated with CCR management. Combined, these engineering projects will reduce the total number of CCR operating units from 10 to six. In addition to closing operating units, APS has other capital projects scheduled or in progress at Cholla and Four Corners focused on minimizing CCR impacts to the environment.

Coal Ash Reuse Table

Nuclear Waste

The Palo Verde Education Center includes a
model of dry cask storage used at the
Palo Verde Generating Station.

Nuclear waste from our Palo Verde Generating Station is managed in compliance with the Nuclear Regulatory Commission and the Institute of Nuclear Power Operations requirements. These agencies conduct regular audits and the audit reports are reviewed by the Pinnacle West Nuclear and Operating Committee . This committee is selected by the Pinnacle West Board of Directors on at least an annual basis. The committee reports regularly to the board on overall performance of Palo Verde, including operations, safety, legal compliance, key performance indicator results and trends, and any significant incidents or events.

We have a comprehensive waste management program and training that is recognized by the Nuclear Regulatory Commission during inspections as an industry leader. Due to the sensitivity of the business and maintaining the highest level of security, our process and procedures are not for public disclosure.

NRC Team Inspection Report - Palo Verde Generating Station (January 2017)
NRC Security Inspection Report - Palo Verde Generating Station (September 2017)

All employees are required to complete training that includes classroom and computer-based
courses and a practical before being able to enter the Radiological Control area. As part of the training,
they are also educated to minimize what they take in the area to help in reducing radioactive waste. Employees are required to refresh their training every four years and contractors every two years. There is additional required training for all employees that handle the packaging and shipping of the waste. 

Palo Verde produces high-level nuclear waste in the form of spent fuel 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 below 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


Prior to the development of natural gas and the widespread use of electricity, a synthetic gas made of either coal or gas was manufactured for heating and lighting purposes. This manufactured gas was commonly used in the United States beginning in the late 1800s, with as many as 1,500 facilities eventually operated across the country. Thirteen of them were located in Arizona, eight of which were operated by APS predecessor companies. 

Beginning in 1987, APS performed investigations to establish the extent and location of residues at all its former manufactured gas plant (MGP) sites. We have been working with oversight from Arizona Department of Environmental Quality Voluntary Remediation Program to remediate its remnant MGP sites. 

Preparation for the remediation involves extensive planning, developing designs and specifications, defining the extent of impacts, developing remedial strategy, community engagement, obtaining various permits and approval from ADEQ. In 2018, APS completed remediation at the Grant Street site in Phoenix and is working to obtain the “no further action” determination in early 2019. In 2018, additional research and site investigation was started for the MGP sites located in Miami and Douglas, the last two of the original eight MGP sites. These sites are scheduled to be completed by 2020.

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