The Tailings Storage Facility (TSF), which is basically a huge pile of mine tailings (such as the Ray Mine along Hwy 177) and will cover the 'tail' end of the Tortilla Mountains AZT #15 passage.
(Too bad the latest trailhead parking improvement project will be for naught)

Here's the link to view the Environmental Impact Statement pdf file.
Most relevant to the AZT: APPENDIX G - ARIZONA TRAIL RELOCATION ANALYSIS pdf file.
Good view of where and how high the TSF will be: FIG 2 - SITE PLAN LAYOUT - RIPSEY WASH TSF
"Please send your comments before March 21, when the Corps will close the official public comment period."