Cholla Power Plant has 33 groundwater monitoring wells, 32 of which have been polluted above federal advisory levels based on samples collected between March 08, 2016 and November 26, 2019. Groundwater at this site contains unsafe levels of sulfate, lithium, cobalt, boron, molybdenum, radium, fluoride, selenium, arsenic, chromium and lead.Site description
Arizona Public Service Company’s Cholla Power Plant opened in 1962 and is located near Joseph City, Arizona. The plant has four coal-fired generating units that can produce 767-MW. Unit 2 was closed in October 2015. Unit 4, which is owned by PacifiCorp and participates in a seasonal power exchange with APSC, was retired in 2020. Units 1 and 3 are planned for retirement in 2025. The plant operates four CCR units regulated under the CCR rule: the Fly Ash Pond (430 acres), Bottom Ash Pond (105 acres), Bottom Ash Monofill (41 acres), and Sedimentation Pond (1.3 acres). Cholla Power Plant is among the U.S. Environmental Protection Agency's list of potential damage cases, indicating that coal ash disposal at the site has potentially polluted groundwater or surface water at levels which threaten human health and the environment.