The US EPA has proposed criteria for the environmentally protective use of chat in transportation construction projects carried out in whole or in part with federal funds, and in concrete and cement projects. Chat is a gravel-like waste created from lead and zinc mining activities in the Oklahoma, Kansas, and Missouri tri-state mining region between the late 1800s and mid 1900s. The proposed criteria involve safely encapsulating chat particles in asphalt or cement and concrete.

Currently about 100Mt of chat contaminated with lead, zinc and cadmium are located in the tri-state mining district. The proposed criteria will help reduce these piles, thus reducing the amount of chat particles that are spread by wind, water or air into the surrounding environment.

The tri-state district covers approximately 2500 square miles and includes parts of Ottawa County, Oklahoma; Cherokee County, Kansas; and Jasper and Newton Counties, Missouri. It includes four Superfund National Priority List (NPL) sites: Cherokee County, Tar Creek (Ottawa County), Newton County Mine and the Oronogo-Duenweg Mining Belt.
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