|
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 remediated sites in Phoenix and Prescott.
In 2002, APS removed 300 feet of a lampblack pipeline in downtown Phoenix. The pipeline was removed on APS property to reconfigure a parking entrance and improve surface water storm drainage. During the project, we removed 172 tons of special waste that included soil, the pipeline, vaults and lampblack.
Yuma, Arizona is in the southwest corner of the state bordered by Mexico and California. The Colorado River flows between those borders and was the narrowest crossing point for pioneers during the gold rush of the 1840s. Called the Yuma Crossing, the area is one of 23 areas designated by the United States Congress as a National Heritage Area. More than 1,500 acres of shoreline make up the Yuma Crossing and much of it was choked with reeds and non-native vegetation.
The community’s vision for the area includes clearing the reeds and exotic species, installing bike walking paths, an 80-mile equestrian trail, butterfly and hummingbird gardens, boat ramps, and native cottonwoods, mesquite and other species.
Also in the area were remnants of a historic Manufactured Gas Plant (MGP) which APS began remediating in 2001 and completed in 2002. The money the company invested in cleaning up the site was applied to the National Heritage Area’s matching grant program, giving Yuma access to additional funding for the property.
During remediation, APS removed 37,000 tons of soil and treated more than 810,000 gallons of water. The excavation depth averaged 25 feet with a maximum of 35 feet. The site was located adjacent to a railroad spur and the city’s water treatment facility, requiring shoring to be installed to protect those properties. The shoring allowed crews to excavate maximum amounts of contaminated soil without affecting the structures. A total of 1,110 square feet of shoring and 2,400 square feet of soil nailing were used to secure the structures.
|
