SHERIDAN — City of Sheridan Public Works Director Nic Bateson has confirmed that fluoride is now being added to the water supply for city and Sheridan Area Water Supply customers.
The addition of fluoride, originally scheduled to begin Thursday, began on Monday at both the Big Goose and Sheridan water treatment plants.
Liquid fluorosilicic acid is being added to a level of 0.7 parts per million, the level recommended by the U.S. Department of Health and Human Services.
The Environmental Protection Agency’s maximum contaminant level goal for fluoride is 4 ppm.
The fluorosilicic acid is held in a 2,000-gallon storage tank at the Sheridan water treatment plant and a 500-gallon tank at the Big Goose plant. Each day, the fluoride will be fed to a “day tank,” which holds the maximum dosage for any given day, city Utilities Manager Dan Roberts previously told The Sheridan Press.
Dosage from the day tank is a slow, steady feed that is controlled by a supervisory control and data acquisition computer system. The SCADA system will continuously evaluate if the water has any naturally occurring fluoride and adjust the dosage accordingly to keep it at 0.7 ppm.
Bateson said the cost to add fluoride to the water system will be approximately $22,500 per year, or 9 cents per month, per customer.
“The nice thing about integrating the entire system into the conventional upgrade project is it’s all integrated into our automated system so it’s not like it’s an additional operation for our plants,” Bateson said.
While water rates did increase this year, Bateson said the increase was not a direct result of the addition of fluoride to the water supply. Three years ago, City Council passed a resolution to raise water and sewer rates approximately $3 every year based on a 20-year financial model that takes into consideration upcoming projects and maintenance costs.
Bateson noted that there was no increase in rates last year due to grants received and tight control on operation costs. This year’s increase in rates was approximately $2.
Addressing concerns about arsenic present in the fluorosilicic acid being used, Bateson said the city will continue to be under close scrutiny for water quality by the EPA, the Department of Environmental Quality and other regulatory agencies.
“We will be under the same microscope as we’ve always been at all the different acceptable levels for water quality,” Bateson said.
Water Treatment Superintendent Tom Manolis calculated a figure of .000128 milligrams per liter of arsenic present in the water based on the fluoridation level of 0.7 ppm. Bateson said that is an amount so small that no testing machine could detect it.
The EPA’s maximum contaminant level for arsenic is 10 parts per billion. The level of .000128 mg/liter converts to 1.281462 parts per billion.
“The levels of all the chemicals within our water will continue to be examined and are well within and well below any of the required standards from the regulatory agencies that we report to,” Bateson said.
The process to add fluoride to Sheridan’s water supply was initiated in December 2010 when City Council passed a resolution directing water treatment staff to monitor fluoride levels and the public works department to incorporate fluoridation equipment into its current and future budgets. That resolution was brought about when more than 230 health and dental professionals submitted a petition requesting water fluoridation to help with widespread dental decay being seen by health and dental professionals.
City Attorney Greg Von Krosigk previously told The Sheridan Press that he interpreted the approval of the resolution and subsequent approval of the budget that included costs to install fluoridation equipment as approval for initiating fluoridation of the water.