Chlorine discharge violations from drinking water treatment plant occurred December 2005 through September 2006, harming aquatic environment
The Oregon Department of Environmental Quality (DEQ) has fined the city of Newport $61,533 for repeated illegal discharges of wastewater containing excessive amounts of the toxic chemical chlorine into Anderson Creek, which is a tributary of Big Creek and the Pacific Ocean.
The discharges, which occurred on 108 separate days between Dec. 22, 2005 and Sept. 12, 2006, were of wastewater generated by washing out filters from the city’s drinking water treatment plant. Discharges continued long after DEQ warned the city about the illegal discharges in a Feb. 27, 2006 Pre-Enforcement Notice. The city may appeal within 20 days after it receives the penalty.
In assessing the penalty amount, DEQ officials were particularly concerned by the city’s failure to take action to either prevent the discharges or promptly work to reduce or eliminate them once they began. The chemical chlorine, which is used to kill bacteria in drinking water, is highly toxic to fish and other aquatic life. A DEQ survey of aquatic insects in Anderson Creek, conducted in August 2006, found insect numbers and diversity were two thirds lower downstream of the city’s filter backwash discharge point than insect numbers and diversity immediately upstream of the discharge point. The chlorine level in the wastewater was as high as 0.5 milligrams per liter (mg/L), which is far above the state water quality standard of 0.019 mg/L for chlorine.
The drinking water treatment plant generates wastewater when plant operators backwash filters used for removing suspended solids in raw water. The plant uses chlorination prior to filtering to kill bacteria. Normally, the backwash wastewater is sent to a settling pond to allow solids to settle out before the wastewater is recycled at the plant. By December 2005, however, the city had allowed solids to accumulate in the pond to the point where adequate settling couldn’t take place and the filter backwash wastewater could not be recycled to the plant. Instead, the city allowed the wastewater to discharge into Anderson Creek. Discharging wastewater to state waters without a permit is a violation of state law.
The city could have prevented any discharge by dredging the settling pond before allowing solids to accumulate to the point where the settling pond was rendered ineffective, according to DEQ. The city also failed to promptly stop the illegal discharges by dredging the pond even after its own sampling found high concentrations of chlorine in its wastewater. In a Dec. 22, 2005 letter, the city first notified DEQ of the discharges and said it would “correct this problem as soon as we can.” DEQ issued the city a Pre-Enforcement Notice in February 2006, advising Newport that the discharges were violating state law. Despite the notice and the city’s own assurance it would promptly correct the problem, the city did not apply for a special permit to conduct the pond dredging until late July, and did not award a dredging contract until mid-August 2006. The harmful discharges ceased Sept. 25, 2006, when dredging was completed.