WATER FLUORIDATION
Fluoride is a naturally occurring element that when consumed in moderate amounts (approximately 1 milligram per liter (mg/L)) is important to good tooth development and the prevention of tooth decay. However, when fluoride concentrations in excess of 1.5 to 3.0 mg/L are consumed, a chemical combination can occur within the tooth enamel, resulting in mottled and permanently discolored teeth. Concentrations in excess of 4 mg/L can be toxic.
Fluoride is naturally present in the Town's existing water supply although at very small concentrations (less than 0.1 mg/L).
Adding fluoride to public drinking water supplies has been in practice since the mid 1940's. The Maryland Department of the Environment (MDE) supports the fluoridation of public drinking water supplies and encourages municipalities to do so, if feasible.
PROCESS
There are three types of fluoride used in today's public drinking water supplies: sodium fluoride, sodium silicofluoride and hydrofluosilicic acid. The first two types of fluoride are typically supplied in bulk, crystalline form and are regularly used at water treatment plants. Hydrofluosilicic acid is supplied as an aqueous solution (55 gallon drums) and is commonly used at groundwater well houses. If the Town were to decide to add fluoride to its drinking water, hydrofluosilicic acid would be the most cost effective and safest type of fluoride to use.
In order to maintain uniform fluoride concentrations of 1.0 mg/L throughout the entire water distribution system, all or a majority of the well houses in Town would require the installation of fluoride dosing systems. Computer modeling of the distribution system would be necessary to determine specifically how many and which well houses would require fluoridation systems to be installed.
EQUIPMENT
The use of the hydrofluosilicic acid is advantageous because of the relatively inexpensive equipment required as compared with the equipment typically used with powered compounds. The hydrofluosilicic acid is added directly to the water by a chemical dosing system typically consisting of a chemical feed pump, analyzer/controller, injector, drum scale and a 55 gallon drum of the acid solution. Dilution of the acid prior to adding to the water is not recommended because of the hazards involved in handling the acid and the errors associated with dilution.
Installing fluoride systems in the Town's well houses would require additions (approximately 80 sq. ft.) and or modifications to be made to the existing buildings to accommodate the additional equipment.
The attached Figure depicts a schematic lay-out of a fluoridation system for a typical Poolesville well house.
STORAGE AND HANDLING PRECAUTIONS
Hydrofluosilicic acid is corrosive and dangerous and must be stored and handled carefully. Operators are required to be trained and certified in the handling and use of the acid as a serious injury could result if mishandled or misused. Operators must wear protective clothing when handling the acid.
To prevent possible contamination from occurring, fluoride chemicals should be stored in a manner that isolates them from other chemicals. In addition, the storage area for the chemicals needs to be well ventilated and have a secondary containment device should accidental spills occur.
TRAINING
As previously mentioned, each operator must attend mandatory MDE training prior to working with fluoride. The training covers handling, safety procedures, process mathematics, feed rates, and emergency procedures. The State of Maryland requires that all operators working with fluoride have Class 2 certification.
COSTS
Design and construction costs to equip one well house with a fluoridation system is estimated to be approximately $ 75,000. As such, the costs for supplying the Town with a complete fluoride system are estimated to be $ 525,000 to $ 600,000 depending on the exact number of well houses to be retrofitted.
Annual operation and
maintenance costs would consist primarily of the hydrofluosilicic acid and
the fluoride testing equipment. We estimate the operation and maintenance
costs would range from $18,250 to $ 20,250 per year.
A breakdown of our order of
magnitude capital cost estimate is attached.
ADVANTAGES RELATIVE TO POOLESVILLE
Fluoride, when consumed in moderate amounts (approximately 1 mg/L), is important to good tooth development and the prevention of tooth decay.
DISADVANTAGES RELATIVE TO POOLESVILLE
Due to the low flow rates of the Town's groundwater wells, the hydrofluosilicic acid dosing will also be very small (e.g., drops per minute). Accurately dosing the low flow rates of the Town's wells could be tricky and would have a small margin of error.
When fluoride concentrations in excess of 1.5 to 3.0 mg/L are consumed, a chemical combination can occur within the tooth enamel, resulting in mottled and permanently discolored teeth. Concentrations in excess of 4 mg/L can be toxic. Should fluoride overdosing accidentally occur, the effects could be catastrophic. (Note: In the Fall, 1993, the Town of Middleton, Maryland reportedly had equipment malfunction resulting in the overdosing of fluoride into their drinking water supply. The Town had to completely drain and flush their water system and provide their customers with bottled water while the problem was corrected. The Town, which has a groundwater well system similar to Poolesville, no longer adds fluoride to their water supply.)
Hydrofluosilicic acid is corrosive and dangerous to handle and will increase the potential for accidental operator injury. Operators will need to wear protective clothing and exercise extreme caution when handling the chemical.
Adding fluoride to the Town's water supply will require the installation of chemical dosing equipment and building expansions and or modifications costing approximately $ 525,000 to $600,000 depending on the number of well houses retrofitted. Water system operations and maintenance costs would be expected to increase by approximately $18,250 to $ 20,250 per year.