This graph shows the trend in the pounds of chemicals reported to TRI as disposed of to land. The metal mining sector accounts for most of the TRI chemical quantities disposed of to land.
Underground injection involves placing fluids underground in porous formations through wells.
The RCRA Subtitle C Disposal category in TRI includes disposal to landfills and surface impoundments authorized to accept hazardous waste under the Resource Conservation and Recovery Act (RCRA). RCRA design standards include a double liner, a leachate collection and removal system, and a leak detection system. Operators must also comply with RCRA inspection, monitoring, and release response requirements.
From 2007 to 2017:
- On-site land disposal increased by 35% (from 2.0 to 2.7 billion pounds).
- Recent fluctuations are primarily due to changes in TRI chemical quantities disposed of to land on site by metal mines.
- “All Other land disposal” in the figure includes disposal: in landfills and surface impoundments that are not regulated under RCRA Subtitle C; to soil (land treatment/application farming); and any other land disposal. Most of the TRI chemical quantities reported as “other land disposal” are from the disposal of waste rock at metal mines.
- Disposal to land is often regulated by other programs such as the Resource Conservation and Recovery Act (RCRA).
- Land disposal trends are largely driven by the metal mining sector, which accounted for 72% of land disposal quantities. Select the “Land Disposal, Excluding Metal Mining” button to view the land disposal trend with metal mines excluded from the analysis.
Metal mining facilities typically handle large volumes of material. In this sector, even a small change in the chemical composition of the mineral deposit being mined can lead to big changes in the amount of TRI-listed chemicals reported. In recent years mines have cited changes in production of waste rock, changes in the chemical composition of waste rock, and the closure of a heap leach pad as the primary reasons for the reported variability in land disposal of TRI chemicals. Changes in waste rock composition can have an especially pronounced effect on TRI reporting because of a regulatory exemption that applies based on a chemical’s concentration in the rock, regardless of total chemical quantities generated.
Regulations require that waste rock, which contains contaminants, be placed in engineered piles, and may also require that waste rock piles, tailings impoundments, and heap leach pads be stabilized and re-vegetated to provide for productive post-mining land use.
For more information on the mining industry, see the Metal Mining sector profile.
This graph shows the trend in the pounds of chemicals reported to TRI as disposed of to land, excluding quantities reported by the metal mining sector. The metal mining sector accounts for most of the TRI chemical quantities disposed of to land.
From 2007 to 2017:
- Total on-site land disposal for all industries other than metal mining decreased by 13%.
- Excluding releases reported by metal mines, the chemicals disposed of to land in the largest quantities are: barium and barium compounds (18%), manganese and manganese compounds (13%), and zinc and zinc compounds (11%).
- While disposal to land has decreased in many sectors, the metal mining sector drives overall land disposal trends. See the graphic Land Disposal by Industry for more information.
This page was published in March 2019 and uses the 2017 TRI National Analysis dataset made public in TRI Explorer in October 2018.