Matt will collect five confirmation samples from the well today. Once the confirmation samples are collected, we talked about the well being turned off, inspected, and shock chlorinated. Matt said three routine samples collected in the distribution system the same day were coliform absent and measured chlorine residual between 0.4 mg/L and 0.6 mg/L.

Matt emailed me on Saturday June 18th that two of the five confirmation samples were E. coli positive. The well has been turned off until the city can take further action. Chlorine residual at the pump station on Friday after collecting samples was 0.56 mg/l. As a precaution, chlorine dosage was increased and measured at 0.65 mg/l on Saturday morning.

On Tuesday June 21st, I spoke with Matt about confirmed E. coli and forwarded DWS letter outlining next steps. We discussed need to do an advisory. Polk Well #1 sends water directly to the Polk/River Wellfield Plant where it is chlorinated, filters before entering reservoirs, and then into the distribution system. Extensive flushing was done in the area served by the plant from north to south. The north end is furthest from the plant and staff worked to pull water back toward the plant. He provided a map listing flush times and chlorine residuals at each hydrant that was flushed. Four samples were collected in the affected area with results available on Wednesday. He noted they exceeded flushing times to turn over the water that was in the main lines.

Four samples collected on 6/21/22 in the area flushed were all coliform absent. The City provided documentation to demonstrate 4-log inactivation for the Polk/River Wellfield serving EP-B. An advisory not needed.