Manufactured gas plants (MGPs) operated from the late 1800s to about 1950, making synthetic gas for domestic heating and lighting purposes. Several of APS’s predecessors operated plants in Arizona communities, including Phoenix, Globe, Miami, Prescott, Douglas and Yuma. The manufactured gas process created byproducts including lampblack, tar and oils, some of which remained at the sites after operations ceased. APS has voluntarily investigated and characterized these historical MGP sites. We have entered the MGP sites into the Arizona Department of Environmental Quality’s Voluntary Remediation Program, which specifically allows for the voluntary investigation and remediation of environmentally impacted sites in Arizona. We have completed and received closure from ADEQ for the Prescott, Yuma and Globe sites. APS has completed the soil removal and utility isolation activities at the 501/505 Phoenix MGP site in 2013 and will implement bioventing in 2016. APS has initiated pre-remedial actions at the Grant Street MGP, located in Phoenix. Additional characterization and development of the remedial action plan will be completed in 2016, and the remediation is scheduled for early 2017.