Annual water report: Usage down, plant operation continues to improve

Annual water report: Usage down, plant operation continues to improve

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Atikokanites used twenty percent less treated water in 2016 than a year earlier, the annual report on the Town’s drinking water system indicates.

The warmer winters of 2015-16 and 2016-17 are the most likely cause of the decline, as the threat of frozen water lines eased. Water use rose almost twenty-four percent in 2014, as the area experienced a colder than usual winter (2013-14) and massive problems with frozen water lines. The Town was advising people to allow a trickle of water 24/7 to prevent water line freezing.

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Water use increased again in 2015, by about five percent. But the 2015-16 winter turned out far milder than the previous two, as did 2016-17, and frozen water lines were uncommon.

All told, the plant treated 656,000 cubic metres of water in 2016, about 1,800 cubic metres a day. That’s well within the plant’s rated capacity of 6,000 cubic metres a day. Daily demand peaked at 3,400 cubic metres, with just a few days in March and August seeing demand of more than 3,000 cubic metres.

Better compliance

The operation of the plant continues to improve, based on the number of non-compliance incidents recorded in the annual inspection conducted by the province. The February, 2016 inspection identified six incidents of regulatory non-compliance; in 2015, there were eight, in 2014 there were ten, and there have been as many as 23 (in 2010) over the past decade.

The Town has invested in a number of upgrades to equipment and operational procedures to address the problems noted in the inspection. The most difficult issue remains the occurrence of low chlorine residuals in the water that reaches some parts of town. Drinking water is required to have 0.05 milligrams of free chlorine per litre (that’s 50 parts per billion) to ensure disinfection is still occurring.

Part of the problem is that some areas of the system are dead ends, where circulation is intermittent. The Town has installed bleeder lines to address some of them, and plans to add more. But much of the problem is in the age of the distribution system, and permanent solutions will require the installation of new water mains and water lines.

Adverse incidents

There were 13 adverse water quality incidents during the year, the fewest since 2012. Only one of them involved any indication of bad water. On July 4, a routine sampling of treated water collected from a Don Park residence tested positive for the presence of total coliforms. (157 such routine samples were tested during 2016.)

“Total coliforms are a group of bacteria commonly found in the environment, for example in soil or vegetation, as well as the intestines of mammals, including humans. Total coliform bacteria are not likely to cause illness, but their presence indicates a water supply may be vulnerable to contamination by more harmful microorganisms.” (From a New Brunswick fact sheet on drinking water)

The finding was reported to authorities (Ministry of Environment, health unit), and corrective action (system flushing, re-testing, and monitoring of secondary disinfection in the affected area) taken. Further testing of water in the area turned up no further evidence of total coliforms or E. coli.

(“Escherichia coli (E.coli) is the only member of the total coliform group of bacteria that is found only in the intestines of mammals, including humans. The presence of E.coli in water indicates recent fecal contamination and may indicate the possible presence of disease-causing pathogens, such as bacteria, viruses, and parasites. Although most strains of E.coli bacteria are harmless, certain strains, such as E.coli 0157:H7, may cause illness.” New Brunswick)

Five of the adverse incidents involved equipment failures affecting operation of the treatment plant, two of which led to community-wide boil water advisories. There were also seven localized boil water advisories, usually as a result of emergency work on water mains and water lines.

  • In November, treated water samples were analyzed for the presence of a wide range organic (e.g., arsenic, mercury, uranium) and inorganic parameters (various acids, pesticides, herbicides, PCBs, volatile organics). All results were below the associated Ontario drinking water quality standards.
  • Treated water was tested four times (February, May, August, and November) for nitrates and nitrites; all results were below the associated Ontario drinking water quality standards.
  • Treated water was tested four times (February, May, August, and November) for trihalomethanes, a by-product of the chlorination process. The running annual average was 84 micrograms per litre (or 84 parts per billion), which is below the standard of 100. The sample results ranged from 42 micrograms per liter in February to 147 micrograms per litre in August.
  • The annual drinking water report also contains results on the performance of the treatment plant filters, and on the sampling of discharged waste water from the plant.


The water treatment process

Atikokan’s drinking water goes through a complex, five-stage treatment process that includes chemical coagulation, sand-blasted flocculation, clarification, rapid sand filtration, and free chlorine disinfection.

Given the nature of the source water from the Atikokan River, all five stages are vital to remove bacteria, rotting organic material, and more insidious threats like Cryptosporidium and Giardia. This is a far more thorough treatment process than any simple filter can provide.

Once in the station, a coagulant (polyaluminum chloride) is added to the raw river water, and the water and coagulant are mixed rapidly together. The coagulant works on the colloidal particles in the water (these are less than one micron – one thousandth of a millimetre – across). These colloidal particles carry surface electrical charges that cause them to repel one another. The coagulant carries an opposite charge that neutralizes their surface charge, and leads the particles to start clumping together in micro ‘flocs’.

In step two, microsand and polyacrylamide are added to the water. These act as flocculants – they cause particles suspended in the water (both larger particles and the micro flocs created during coagulation) to come together in larger flocs (masses) heavy enough to settle to the bottom of the water.

In step three, clarification, the water is allowed to settle, and the flocs sink to the bottom of the tank. This process removes about sixty to seventy percent of the natural organic matter found in the river water.

The water then flows from the top of the settling tank into the filter units that make up stage four.

There, any suspended particles left are removed as the water is passed through four dual-media filters (each filter is composed of anthracite and silica sand on a layer of support gravel). These filters are cleaned periodically by reversing the flow of water through them, using pumps. (Back-washing.)

Finally, chlorine gas (a disinfectant), a sodium carbonate solution (to adjust the pH, or acidity level, of the water), and hydrofluorosilicic acid (fluoridation) are added in the disinfection stage. The treated water is stored in specially designed tanks that ensure the disinfectants have enough time to work before the water is pumped into the distribution system.

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