EPA was contacted directly by IDNR Spencer Field Office staff and informed of possible mercury at the City of Newell's water treatment plant. IDNR had been contacted earlier by the water system operator and informed of the discovery of the mercury in a filter in the backflush wastewater basin inside the treatment plant. the operator was instructed to put out a notice of possible mercury contamination to everyone on the drinking water distribution system and then to collect samples from the treatment plant where the mercury was discovered and throughout the distribution system in the City of Newell. Samples were collected in the afternoon of July 8, 2020 and driven to the State or Iowa laboratory for analysis. Verbal description was over 2 tablespoons observed on the filter in the pit. The pit is currently isolated from the distribution system and will not likely be need for use in back-flushing again for approximately a week. It is unknown how long the mercury has been there as the water is normally too murky to see all the way to the bottom where the filter is. The source of the mercury is currently unknown but the operator knows that several devices in the treatment plant likely contains mercury. IDNR sent EPA a request for federal assistance on July 9, 2020.
EPA mobilized to the site on July 9, 2020. The suspected mercury was submerged in approximately one foot of water in a pit used to contain wastewater when the facility’s iron filter is backwashed. The backwash pit empties to the sanitary sewer, and has no connection to the municipal water supply. A sample was collected from the pit and visually confirmed to be mercury. It is believed that the water is suppressing the mercury vapors. It is not immediately clear how the mercury got in the backwash pit. Two mercury containing apparatuses located in close proximity to the backwash pit were visually checked and did not appear to be compromised.
