Union Station North Wing is a mixed-use, five-story building with a three level subgrade parking garage. RK Water was contracted to design a permanent treatment system to meet stringent effluent limits of the certified discharge permit. Discharge of treated groundwater at the Union Station North Wing building is governed by an individual permit issued by the Colorado Department of Public Health and Environment (CDPHE). The treatment system was designed to remediate Arsenic to below 20 parts per trillion (ppt), and Selenium to levels below 4.9 parts per billion (ppb). RK Water currently operates the treatment system.