City of Salem
The City of Salem owns and operates the Geren Island Water Treatment Plant near Stayton, Oregon, and has used it for generations to provide safe drinking water to the City and surrounding municipal areas. The treatment plant receives water from the North Santiam River and has utilized a roughing filter, acres of slow-sand filtration basins, and chlorine disinfection to continuously treat the water in compliance with the Surface Water Treatment Rule. Unfortunately, in 2018, a combination of environmental factors introduced cyanotoxins into the source water, and this historical treatment process was not able to remove these from the system and the only solution for several weeks was providing bottled water or water trucked in from other sources to serve the entire population. To address this issue in the future and ensure safe—and resilient—drinking water resources, the City invested over $50 million in the design and construction of an ozone treatment facility at the treatment plant. This treatment utilizes a powerful disinfectant called ozone to aid the roughing and slow-sand filters in destroying the cyanotoxins that filtration cannot remove.
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Combined with the tried-and-true slow-sand filtration method, ozone treatment (another proven method) delivers excellent results in eliminating cyanotoxins. Some additional benefits of ozone treatment include treatment against other harmful organisms in the surface water, such as giardia and cryptosporidium, more stable year-round maintenance, a reduction in the amount of chlorine used, working harmoniously alongside the other treatment steps, and leaving no trace of ozone in the final water product. In addition to the Ozone Facility, the City and Carollo Engineers have also made another $50 million in improvements to the plant, including the replacement of the slow-sand underfilters, cleaning and resanding of the filter beds, and the construction of a 30-foot-diameter Ranney collector well to utilize as a source of water when the turbidity levels in the river exceed the levels that can be adequately treated in the roughing filter.
