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Kim ey ))) Horn Page 18 United States Environmental Protection Agency's (USEPA) LCR component of the SDWA establishes action levels for lead and copper at consumers taps. Typically, sampling in a representative number of customer's taps is required every three years. The LCR establishes action levels of 0.015 mg/L for lead and 1.3 mg/L for copper, respectively at consumer's taps, and requires corrosion control measures be implemented if more than 10 percent (90th percentile) of the tap water samples collected during any monitoring period exceed these levels. Lead sources in drinking water include lead service lines (LSLs), soldered joints, and brass (many of which are found on the customer's side of the meter). Copper plumbing and fixtures are primary contributors to its presence in the drinking water. Elevated lead and copper concentrations in drinking water can be correlated to the water chemistry's ability to propagate corrosion. Water is the universal solvent and there are many factors that contribute to corrosion, such as stray current (lightning), plumbing workmanship, defects in materials, velocity, contact with dissimilar metals, etc. Regardless of the water system, corrosion can and will occur. The LCR is in place to help guide utilities in controlling the rate of corrosion through setting action levels for lead and copper. Exceedance of these action levels described herein will result in regulatory enforcement of Optimal Corrosion Control Technique (DCCT), which requires utilities to investigate and implement corrosion control measures to mitigate lead and copper corrosion. Indian River County Utilities remains compliant with the provisions of the Safe Drinking Water Act (SDWA), including the Lead and Copper Rule (LCR), a federal law that intends to protect public health through minimizing lead (Pb) and copper (Cu) levels in drinking water, primarily by reducing water corrosivity. The following sections discuss IRCU's historical LCR sampling data. LEAD SAMPLING DISCUSSION Lead enters drinking water primarily from the lead -containing solder and flux material used to join copper pipes in home plumbing and new cast -brass faucets (Cardels and Sorg 1990). The most important water quality parameters related to lead solubility are pH, alkalinity, dissolved inorganic carbonate, and ortho- phosphate levels (AWWARF 1990). A recent survey of lead at the consumer tap concluded that the highest lead levels were found in the newest plumbing systems onto which household electrical systems were grounded (Lee et. al. 1989). It was also demonstrated that controlling the pH values in water in the distribution system to greater than 8.0 and the addition of blended phosphate inhibitor reduced the home tap lead concentrations. Corrosion control methods that rely on adjusting the pH have been shown to be a cost-effective, reliable and the more common methods of treatment currently in practice today (Taylor, et.al., 1992; Vinci 1991; Maas 1991; McNally, et. al., 1993). IRCU utilizes pH, alkalinity and calcium carbonate adjustment techniques for finished water stabilization. IRCU has maintained compliance with lead samples below the 901h percentile action level of 0.015 mg/L. From 2011 through December 2015, 901h percentile data displayed a downward trend. Since this sampling event, lead 901h percentile data has trended upwards with 90th percentile data increasing to 0.003 mg/L. Although 90% of the samples were at this value or lower, the average concentration of lead in the samples has maintained relatively consistent, with exception of the May 2016 LCR sampling event. In this instance, there was one outlier sample that was approximately 17 times greater than the next highest ranked lead sample, which contributed to the overall average increase but no impact to the 90th percentile value.