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Water district meets demand of expanding customer base.

Today, 98 percent of U.S. drinking water is treated with chlorine as the preferred method of sanitizing and disinfecting. With such widespread use, it is important that the method of chlorination be easy, safe to operate, and effective. Many companies and municipalities are looking for alternatives to the two most common methods of chlorinating drinking water - chlorine gas cylinders and sodium hypochlorite (liquid bleach). These traditional methods have presented safety and handling problems in the past.

The SJWD water district in Spartanburg County, South Carolina, provides drinking water to over 13,000 households, or 36,000 people. The district pumps about 4.5 mgd; peak days average 6.5 MG. The total service area relies on 450 miles of pipe to reach 140 square miles. The SJWD is a consecutive water system, meaning they purchase their finished water supply, primarily, from the nearby Spartanburg Water System. However, as SJWD's customer base has continued to expand to the outer limits of their service area, the chlorine residual has, on occasion, fallen short of the required levels needed to maintain water quality to some outlying areas. SJWD actively sought a system to provide booster chlorination to those outer areas.

Richard E. Culler, P.E., assistant district engineer, stated, "We considered chlorine gas, but our concern was safety. Then we looked at liquid chlorine and safety was also a concern." Because both are considered volatile forms of chlorine, SJWD believed it would not only put their employees and the public at risk, but the district would spend more time and money in safety equipment and safety training. The decision to test the calcium hypochlorite chlorinating system from PPG Industries, Inc., Pittsburgh, Pennsylvania, was unanimous.

The calcium hypochlorite, in tablet form containing 65 percent available chlorine, is delivered into the water source via the system's Series 3000 chlorinator. Specifically, incoming clean water flow erodes the tablet charge as it passes over the sieve plate and discharges through the outlet. In solution with water, it is used as a general disinfectant to destroy bacteria, algae, fungi, and other microorganisms. Chlorination is controlled by the inlet water flow. Higher flows will yield higher chlorine delivery.

SJWD and two neighboring water districts completed a 90-day test of the PPG system, the first system of its kind to be tested in the state of South Carolina. Overall, the system was able to provide consistent chlorine delivery throughout the area being treated - even the outer limits the district originally sought to reach. Additionally, the system proved to be safe and user-friendly, as well as affordable. It delivers the desired concentration without the handling concerns and regulatory restraints involved with chlorine cylinders.

According to Culler, "When we factored in costs, we decided it would be to our advantage to use the PPG system. In fact, we think the system has great potential for use throughout the entire state."

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Title Annotation:SJWD water district in Spartanburg County, South Carolina
Author:Billings, Clayton H.
Publication:Public Works
Date:Jun 1, 1997
Words:479
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