An active aluminum sheet-rolling and plate-rolling mill located in Riverdale, Iowa that has been owned and operated by the Aluminum Company of America (ALCOA) since 1948. Multiple investigations have been conducted at the site, revealing that the manufacturing processes have contaminated the groundwater and soil on the site as well as sediments and fish in the adjacent Pool 15 site of the Mississippi River. Remedies at the site include a groundwater containment, extraction and treatment system, a the establishment of a Technical Impracticability zone on the site where groundwater cleanup is not expected to meet performance standards within a reasonable time frame, elimination of exposure pathways and migration routes to the river, removal of old transformers and other site features that contributed to the contamination, monitored natural attenuation, and other methods of cleanup and monitoring. The site is currently monitored semi-annually and the various remedies in place are performing as expected to prevent unacceptable hazardous conditions.