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From the early 1800s to about 1950, more than 1,500 Manufactured Gas Plants (MGPs) operated throughout the United States. The plants made synthetic gas for domestic heating and lighting purposes. Several predecessors of APS operated plants in Arizona communities including Phoenix, Globe, Miami, Prescott, Douglas and Yuma. The manufactured gas process created by-products including lampblack, tar and oils, some of which remained at the sites after operations ceased.
We began evaluating each site in 1993 to address any remaining material that may have been generated by MGP activities. We began remediating the sites in 1996. We continue to monitor the remediation sites in Phoenix, Prescott and Yuma. APS completed the remediation project in Yuma in December 2002 and completed the site restoration phase of the project in 2003.
Also in 2003, APS completed an interim remedial action on the Phoenix Grant Street MGP site. The Grant Street Apartments are located above the MGP site that was owned by a corporate predecessor of APS. From approximately 1917 to sometime in the 1930s the site contained settling basins that received MGP by-products generated at the nearby 502 South Second Ave. manufactured gas plant. After MGP operations ceased, the site was used for various purposes, including a utility pole storage area.
In 2003, APS submitted an interim Remedial Action Plan (RAP) to the Arizona Department of Environmental Quality to place an engineered cap over the exposed soil within the interior courtyard. In addition, utilities beneath the courtyard were either relocated to the roof or isolated to prevent any requirement to excavate the soils in the courtyard.
APS successfully installed the cap on the courtyard in 2003. The cap consists of a colored concrete plaza on half of the courtyard, and grass and playground on the other half. The landscaped courtyard also included large planters, seat walls, a ramada, barbecue grills and picnic tables for the residents. The playground has a canopy cover and child-safe rubberized surface.
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