Various physical and chemical characteristics of a water distribution system can provide favorable conditions for lead or copper leaching. This study applied geographic information systems (GIS) and a hydraulic model of distribution systems to test the influences of pipe material, pipe age, water age, and other water quality parameters on lead/copper leaching. This study was based on a study performed at North Carolina State University (NCSU) using spatial analysis and geostatistics analysis to test for lead leaching based on water age and the influence of other water quality parameters. Results of the study indicate that higher levels of first-draw lead concentrations most likely occur in buildings constructed between 1970 and 1986 with copper plumbing systems. A long water age to the building and high water temperature also likely contribute to lead leaching into the drinking water. Switching the disinfectant to free chlorine during the "burn out" period then back to chloramines appear not to accelerate lead leaching; however, lead leaching and chloramine decay appear to be correlated. The study is expected to provide utilities with an overview of using a spatial and temporal methodology to test the influences of hydraulic and water quality parameters on lead leaching in water distribution systems. With the methodology, utilities will be able to have a better understanding of the causative factors behind lead leaching in distribution systems and use their scarce resources to focus on high-probability areas for lead leaching. During this special study of lead and copper corrosion in the water distribution system, an assessment of water quality was performed based on the water treatment operation records and water chemistry at the same period when the lead and copper compliance data and the special lead and copper sampling took place. The study was to identify the relationship between water chemistry in the water treatment plant (WTP), and especially, the lead corrosion in the water distribution system. Although no strong correlation was found between raw water/finished water quality at the WTP and lead level in the water distribution system, the results implied that the dominant factors for the lead corrosion lay outside of the water treatment plant, such as from local plumbing materials and stagnant time in the plumbing system.
This paper illustrates the long-term planning challenge for water utilities in the age of conservation using detailed operating data of three sampling entities from the mid 1990s to 2009. The induced behavioral change from conservation measures is found to be of a permanent nature and the unit consumption to be in long-term descent. This in turn may call for a paradigm change in pricing and capacity planning for utilities. The ever-declining per capita consumption alters many commonly acknowledged norms for utilities, in particular for fast growing ones that may have taken on additional financial leverage to support previously anticipated growth. If not managed properly, the full cost recovery mechanism of pricing may force those utilities into an unsustainable future of ever-decreasing total demand and everincreasing cash flow shortfall. Collection of more detailed water demand data in a timely fashion may prove to be a necessary exercise for sound management of median to large water utilities. the water demand by its users would inevitably recover after water conservation restrictions are lifted. This is a critical question of 'if' that has profound impacts on the long-term capacity management for water utilities. In many instances, a constant per capita water demand, as an industry form, is presumed in the long-term capacity and financial planning for those utilities. This implicitly assumes the incremental impact of consumers' water demand in response to conservation can only be used to prevent further 1188
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