In an effort to continue providing the public with high quality drinking water at a low cost to the consumer, the Chester Metropolitan District (CMD) has initiated renovations at the Chester Water Treatment Plant (WTP). These renovations are, in part, to keep abreast of the ever-changing and more stringent drinking water regulations placed on utilities by the Environmental Protection Agency (EPA).

CMD is taking a proactive approach to stay ahead of these regulations and prepare the WTP for future modifications and expansions, as necessary, to keep up with population growth and emerging treatment technologies. As good stewards of your water resources, CMD will use these renovations to provide cost-effective treatment solutions that ensure public health.

The WTP is introducing changes to its current disinfection practice to incorporate
chloramines. The current practice at the Chester WTP is to disinfect with free chlorine, a powerful oxidant and disinfectant. However, chlorinated by-products such as trihalomethanes (THMs) and haloacetic acids (HAAs), which are known carcinogens, are readily formed when free chlorine comes in contact with organic matter in the water. As regulations governing these disinfection by-products (DBPs) become more stringent, utilities are finding alternative ways of providing effective disinfection without the health risk posed by DBPs. Chloramine disinfection provides many advantages over traditional free chlorine disinfection and its use is increasing steadily across the United States and worldwide.
Chloramines are formed when free chlorine reacts with ammonia in water. There are several advantages in using chloramines over free chlorine alone. First, chloramines are much less reactive with organic material than free chlorine, resulting in much lower concentrations of DBPs. This allows not only regulatory compliance, but also assurance that CMD is providing the safest possible product to our consumers. Another advantage in using chloramines is stability; chloramines are highly stable and

provide a persistent residual in the distribution system. This residual helps to maintain the integrity of the distribution system by providing a continuing disinfectant barrier, as well as preventing bacterial regrowth in the system.

Another area in which chloramines provide added benefit is taste and odor. Distinct and unpleasant chlorine taste and odor is very common in waters treated with free chlorine. However, with chloramines there is no chlorine taste or odor, resulting in a more refreshing and pleasant product. Taste and odor incidences often arise as free chlorine reacts with organic matter in the water. Since chloramines are much less reactive with organic matter, the occurrence of such incidents is reduced.

Chester WTP will continue to utilize free chlorine as the primary disinfectant after filtration. However, ammonia will be added to the water as it leaves the clearwell (finished water storage tank) to react with the free chlorine and form chloramines in the distribution system, halting the formation of  DBPs.

Accompanying the new disinfection practice is a system called "flow-pacing." Since only the necessary amounts of ammonia will be used, the flow-paced disinfection feed system will be able to maintain superior chemical dose control.

The switch to chloramines has implications on two populations: kidney dialysis patients and fish owners. For kidney dialysis patients, it is necessary that the chloramines in water be neutralized prior to use in dialysis machines. It is recommended that you check with your physician and equipment manufacturer as to the best means of neutralizing the chloramines. Chloraminated water for any other use (drinking, cooking, and bathing) is completely safe for dialysis patients. Chloramines are toxic only if they go directly into the bloodstream, as they do in kidney dialysis.

Chloramines are toxic to fish because of the fish’s gill structure; chloramines are delivered right into the bloodstream. Therefore, chloramines must be removed from the water. Chlorine is also toxic to fish, however chlorine degrades so rapidly on its own that you may not have had to remove it before. Check with your local pet supply store and they should be able to assist you in finding an acceptable dechlorinating agent.

In addition to the improvements to the disinfection system , renovations are being made to other aspects of the treatment process. The filtration system has been upgraded to accommodate a new air-scour backwash system. This is a superior method of cleaning the filter media that significantly reduces the amount of water required for backwashing. This results in cost savings to the consumer as less water is wasted. The existing media is being replaced with 30 inches of new dual media incorporating silica sand and anthracite coal. State of the art lasers will be added to each filter to measure the clarity of the filtered water.

The water quality laboratory is being updated with advanced drinking water instrumentation. Key treatment parameters will be monitored online, allowing for immediate reaction to any changes in the treatment process. Additional renovations to the WTP will provide the capability to feed alternative chemicals in the treatment process.

CMD has made a commitment to providing the highest quality water possible to Chester County, while keeping the cost to the consumer down. The renovations to the WTP maximize the multi-barrier approach that assures a high quality finished water, while incorporating cost-effective technologies that deliver savings to our customers. The renovations will allow CMD to continue providing a superior product into the distant future by incorporating provisions for expansions and modifications.