The Anaconda Smelter site spans more than 300 square miles and so must be divided into smaller areas to make design and cleanup more manageable. First the site is categorized into five Operable Units (OUs). Two of the OUs are further divided into sub-areas. The following Operable Units and sub-areas, sometimes called Remedial Design Units (RDUs) comprise the Anaconda Smelter Site.
1) Mill Creek
2) Flue Dust
3) Old Works/East Anaconda Development Area
(OW/EADA)—This OU is divided into six sub-areas.
4) Community Soils
5) Anaconda Regional Waste, Water and Soils (ARWW&S)—This OU is divided into fifteen Remedial Design Units.
Each of these Operable Units has a Record of Decision describing the selected clean-up action, including any Institutional Controls (ICs) that are required. ICs and more detailed descriptions of the Operable Units and Remedial design units are in the basics of superfund.