The Society of American Military Engineers (SAME) Denver Post and Philadelphia Post along with the US Environmental Protection Agency (EPA) are hosting a series of webinars based on talks given at recent Design and Construction Issues at Hazardous Waste Sites (DCHWS) Symposiums. The mission of the DCHWS symposiums is to facilitate an interactive engagement between professionals from government and the private sector related to relevant and topical issues affecting applications of engineering and science associated with cleaning up hazardous waste sites. The symposiums also serve as a platform to facilitate the exchange of information, encourage dialogue, share experiences, and build and enhance communication among design and construction professionals. Biochemical reactors (BCR) have become an important treatment unit within passive treatment systems (PTS) designed for mine impacted water; however, operational longevity has remained a persistent concern. This presentation will present an overview on the background, history and principles on the use of BCRs to treat mine-impacted water. This will include a detailed review of the configuration, operation and performance of a typical BCR system and will provide data and observations from two long-term (>8 years) operating BCR systems as examples. This presentation will demonstrate that BCRs are an effective low cost, long term, and sustainable option for meeting water quality targets of mine impacted waters. This presentation will be a continuum of the two presentations previously presented (2018, 2019) in the DCHWS West forums. Both of the previous presentations focused on design, construction, and operation, while this presentation will focus on operation and maintenance, long-term performance, and overall system operational lifespan. To view this archive online or download the slides associated with this seminar, please visit http://www.clu-in.org/conf/tio/DCHWS2_112519/