In situ carbon amendments are materials that are placed underground to remove contamination from groundwater. The amendments are made up of small particles of coal, wood, nutshells or other carbon-rich materials that have been heated to increase the surface area of the particles. Reactive materials such as iron particles or peroxide may be added to help destroy some types of contaminants. Microbes (very small organisms naturally found in the environment) may also be added to promote destruction. The technology is “in situ” because cleanup is conducted in place, without having to pump out groundwater for treatment above ground. In situ carbon amendments most often are used to treat groundwater contaminated with petroleum products and solvents.