M&A’s knowledge of the local hydrogeologic conditions and requirements of the federal Coal Combustion Residuals (CCR) Rule allowed APS to develop a responsive monitoring network and program.

Arizona Public Service

Location: Navajo County, Arizona
M&A designed and oversaw installation and sampling of monitoring wells that fall under the CCR Rule. We reviewed water level, water quality, and hydrogeologic data to develop a program to distinguish background conditions from facilty impacts.


In 2015, the EPA released its final Rule regarding the disposal of CCRs from power facilities. This Rule not only defines CCR landfills and surface impoundments but it also establishes minimum criteria for unit design and operation, groundwater monitoring and corrective action, and closure. It specifies detection and assessment compounds for identifying and, when appropriate, addressing impacts to the uppermost aquifer that can be attributed to a release from a CCR facility.


In accordance with the Rule, M&A designed a monitoring program that involved characterizing background water quality and statistically evaluating downgradient changes at four CCR facilities. The program integrated existing wells to the extent possible.

  • Reviewed the Rule to outline relevant requirements for the Cholla facilities
  • Evaluated hydrogeologic, water level, and water quality data to define and characterize the uppermost groundwater system for each facility
  • Reviewed the existing monitoring networks and developed recommendations for additional monitoring that would be required under the Rule
  • Prepared technical specifications and oversaw the installation of 15 monitoring wells
  • Coordinated the initial “low-flow” sampling of all CCR monitoring wells
  • Developed groundwater flow and transport model to simulate plume migration from two CCR units through closure and into corrective action phase of process
  • Prepared a report summarizing well construction and sampling, along with a preliminary assessment of the completeness of each facility’s monitoring network and recommendations for ongoing monitoring and data analysis