BCRWA has 13 groundwater wells which provide water to the treatment plant. During normal operation, 3 to 6 of these wells are in use at a time. Each well can pump up to 450 gallons per minute. Water from the wells has a pH of 7.54.
When water reaches the treatment plant the first process is aeration. Aeration is a process of mixing air with water. This treatment reduces taste/odor issues and carbon dioxide. By removing carbon dioxide, the amount of lime required for softening (the next step) is reduced.
In 2014 BCRWA replaced our original lime paste slaker with a new high efficiency Chemco Systems lime slurry slaker.
This is the Chemco Systems lime slurry slaker.
Softening occurs in the clarifier (aka solids contact tank) where lime is added to the water which increases the pH to about 10.3. This will remove calcium carbonate hardness as a precipitate. Aluminum sulfate is added in the clarifier to promote this precipitation process. The precipitate is then removed by gravity (settling).
The clarified water moves slowly upward within the clarifier, eventually passing over the weirs. Then through the effluent launder and on to the re-carbonation chamber.
In the re-carbonation chamber, carbon dioxide gas is added to lower the pH and stabilize the water. Water leaving this process has a finished pH of approximately 9.5.
Dual Media Filters
Water leaving the recarbonation chamber is moved to one of four dual media filters. These dual media filters contain 30 inches of media; 18inches of anthracite on top of 12 inches of sand. Through a process of straining, gravity moves the water through the media where any remaining particulate matter is trapped in the filter. The filters are backwashed every 240 hours with both air and water to remove the trapped particulate matter. In March of 2014 a project was completed replacing all filter media.
Chlorine & Fluoride (not shown)
Chlorine (for disinfection) and fluoride are added prior to reaching the 450,000 gallon capacity clear well. Our chlorine residual is approximately 1.0 mg/l in the finished water.
High Service Pumps
Treated water is pumped to the distribution system by high service pumps. There are five pumps available for this, each with the ability to pump 750 gallons of water per minute. During normal system demand, two of these pumps run at a time.
In the distribution system water is stored in 13 water towers. To get water to these towers, booster pumps are strategically located throughout the distribution system to maintain adequate pressure. Finally when you turn on your faucet, gravity feeds the water from the tower, through the lines and to your faucet.
Production Chemistry Lab
All BCRWA production employees are wet chemistry certified to perform public drinking water analyses by the OEPA. Wet chemistry testing in our lab includes: pH, alkalinity, hardness, fluoride, chlorine and stability.
Four of our production employees are also OEPA certified in microbiological testing.
This has been a very brief overview of our treatment process. During 2014 our treatment plant provided 680 million gallons of potable water, which is approximately 1.862 million gallons per day.
For a more detailed analysis of how our process works, why not schedule a water plant tour?