North Table Mountain uses a water purifying technique known as conventional filtration. The first step in the process is to retrieve raw water from Ralston reservoir. After the raw water reaches the treatment plant, it is treated with chemicals. The chemicals cause the particles to clump together. This process is known as coagulation. After the coagulation process has begun, the water is gently mixed. This allows the clumps to get bigger. This process is known as flocculation. Once the flocculation clumps get to be large enough, their weight will cause them to settle out of the water. This last process is known as sedimentation. Next, lime is added to the water to create an appropriate pH for the District customers. Chlorine is then added as a disinfectant to kill any dangerous microorganisms such as Giardia and Cryptosporidium. The water is then filtered through filter beds. Finally, the water passes through the plant's clearwell and then distributed throughout the District.

One of the newest projects that we have completed is the Actiflo® project in 1998. Actiflo® is a treatment that falls under the category of conventional filtration. It does very well in treating water that has a high or low turbidity, color, algae, cryptosporidium, and other unwanted contaminants. The Actiflo® process is a cutting edge development and at the time of installation, our District was one of the first in the country to use it.

The process is essentially the same. Once the water reaches the facility, it is treated with a coagulation chemical. The water then moves into a coagulation tank and then into an injection tank. Once inside the injection tank, microsand and polymer are added. The microsand accelerates the flocculation process by increasing the surface area that the unwanted particles in the raw water have to stick to. The increased weight also allows the particles called flocs to sink to the bottom of the water faster. The water is then sent into a third tank called the maturation tank. Here, the flocs grow bigger through more accumulation and eventually settle to the bottom of the tank. The flocs then are moved into the settling tank where they settle to the bottom. The water itself is now called clarified water. This water is then moved through the lamella tube settling zone where it is treated for any leftover flocs. Finally, the water goes through filtration, disinfection and then distribution. The flocs from the settling tank are retrieved and pumped through a hydroclone. Once inside the hydroclone, the microsand is separated from the contaminants through the use of centrifugal force. Once the microsand is cleansed it can then be reused.

North Table Mountain has an on-site laboratory at the plant so that continuous water testing can occur. For more information on the District's water quality, check out the Consumer Confidence Report.

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As part of our duty to provide quality drinking water, NTM participates in the Source Water Assessment and Protection Act (SWAP). This program is part of the Safe Drinking Water Act (SDWA). Under SWAP, we, as a utility, are required to do an assessment of the total watershed with which our raw water is obtained. As part of this assessment, potential sources of contamination must be identified. Depending on the contaminant, different sources will be ranked a higher danger than others. Likewise, the closer a contaminant is to the source creek, stream, or reservoir, the greater the danger.

There are potential hazards in North Table Mountain's watershed as there are in many other districts. Most all of these come from individual mines, most of which have not been in operation for several years. Various contaminants, particularly metals, can contaminate water sources. Fortunately, there have been no elevated metal levels in the District's source water. Metals are a constituent that is tested for on a quarterly basis.

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