EPA/Homeland Security requirements prompted this massive project for the Portland Water Bureau, which began in 2016. Hoffman is replacing existing open-water Reservoirs 3 and 4 with a buried 15-million-gallon concrete storage reservoir that is 100 feet deep and 800 feet long. Due to the projected 18 inches of tank settlement, the reservoir will be put into service in 2020 but will settle for two years. The existing 150-year-old historic Dams 3 and 4 and the gate houses will also undergo a multi-million-dollar historic restoration. The new tank will be covered with interactive public parks and eight-foot high, 1000-foot-long cascading waterfalls. All the work is being done at the bottom of an ancient moving slide being monitored with 300 prisms beaming up to satellites to track real-time movement of the hillside.