Location: 

• Green Valley, Arizona (Lat/Long 31.817718, -110.992126)
  

Acceptance Into Voluntary Remediation Program (VRP):

• June 24, 2025
  

Contaminants of Concern (COCs):

• Sulfuric Acid

Affected Media:

• Soil
  

What are My Health Risks:

For Soil | There is little to no health risk unless there is contact with skin or ingestion of contaminated soil

Site Summary:

On Oct. 11, 2024, a train derailment occurred at Mile Post (MP) 29.2 of the Union Pacific Railroad (UPRR) Nogales Subdivision near Green Valley, Arizona. A total of 24 rail cars were involved in the derailment. Three tank cars containing sulfuric acid were breached during the derailment, releasing most of their contents, approximately 36,000 gallons, to the ground surface. The released acid entered a stormwater drainage ditch on the west side of the tracks and migrated south. The ditch was dry and not flowing at the time of the incident. A berm was constructed at the southern end of the release extents to prevent further migration. The release area was approximately 600 feet long and ranged from 10 to 60 feet in width. On Oct. 16, 2024, GHD collected 4 background soil samples from areas adjacent to the site. Soil samples were analyzed for pH. Planned additional actions include the vertical and lateral delineation of the sulfuric acid plume, followed by the excavation and removal of sulfuric acid-impacted soil.