Spring Run-Off Program and the Home Sniffing Program
Spring run-off conditions in the North Saskatchewan River vary from year to year and can significantly affect the taste and odour of drinking water. Spring runoff (typically starts mid-March to mid-April) results in an increase in the turbidity, colour, taste & odour of the raw water supply drawn from the North Saskatchewan River. Depending on these conditions, EPCOR adjusts its treatment process to remove odour-causing compounds by adding powdered activated carbon. During the winter months our water treatment plants use direct filtration and we must transition back to our conventional treatment mode of operation prior to spring runoff. This allows us to use powdered activated carbon (PAC) used as a taste and odour control measure. In 2015, conversion to conventional treatment was planned for March 16 at the E. L. Smith plant and March 31 for the Rossdale plant. However, unseasonably warm temperatures in early March resulted in runoff conditions even earlier than anticipated (in fact earlier than any time in the last 20 years). Conversion was moved forward to March 10 and runoff conditions arrived before the transition to conventional operation was fully established. Although raw water odours were relatively low at the time, very strong chlorinous odours were observed in the treated water and these odours persisted for a few days after PAC addition had been started. Chlorine added for disinfection may have reacted with non-odorous organic precursor compounds that were present in the raw water and not effectively removed by PAC.
The Home Water Sniffing Program measures the effectiveness of EPCOR's spring run-off water treatment strategy. A panel of EPCOR customer volunteers rate the odour of the treated water from the hot and cold taps in their home. The Home Sniffing Program ran from February 26 to May 29, 2015 and each day between 97 to 150 volunteer sniffers participated. The overall Customer Satisfaction Rating was 93.9%. This met the performance target of 93.8%.
Treatment for spring run-off taste and odour typically focuses on musty and earthy odours. However, chlorinous odours in 2015 had a significant impact on our customer satisfaction. In 2016, conversion to treatment occurred earlier in the year and an initiative to monitor potential precursors to chlorinous odours (organic nitrogen compounds) on a daily basis was implemented. However, data collected in 2016 may not be as illuminating as anticipated. Preliminary evidence indicates that the actual water quality impact of spring runoff in 2016 was very mild. Efforts will continue to improve future spring run-off operational strategies.