Partial lead pipe replacement

In some water supply areas, problems are experienced with the corrosion of old cast-iron water mains, such that iron (red-water) discolouration can become an aesthetic problem with iron concentrations exceeding several parts per million (mg/1). In such cases, the loose iron corrosion deposits can settle within a lead pipe and absorb lead it is likely that this absorption enhances lead dissolution from the lead corrosion deposit as the equilibrium concentration for the dissolved lead is given less opportunity to be realised. Any disturbance of the loose deposits, such as the scouring effect of high flow, can cause elevated concentrations of lead in the drinking water. As an approximation, lead concentrations can double as a consequence of the interaction with loose iron deposits. Particulate lead may also arise from the physical sheer of pieces of the lead corrosion deposit from within the lead pipe, as a consequence of physical damage (as can occur in partial lead pipe replacement). Vibration from heavy road traffic might also cause pieces of the lead corrosion deposit to sheer. There is some evidence (Cardew, 2009) that the lead... 

Partial lead pipe replacement of the public portion of the lead service lateral is being practiced in some cities. As found in recent US studies (AWWARF, 2008), partial lead pipe replacement is only a marginal strategy for controlling lead concentrations in drinking water at tap outlets. It is generally justified by reducing the liability of the water supplier for lead emissions from domestic pipes. 

There are concerns that partial lead pipe replacement may actually worsen the situation in terms of lead emissions at the tap, based on the recent AWWA (2008) study. The removal of an existing lead lateral can disturb the complex lead hydroxyl-carbonate scale that has formed on the inside of lead pipes over years of service. Flaking of disturbed deposits can elevate particulate lead concentrations. Mechanical disturbance due to partial lead pipe replacement has been shown to elevate lead concentrations at the tap in several other studies (Britton and Richards, 1981 Breach et al, 1991 Hulsmann, 1991 AWWARF, 1990 Wycock et al., 1991 Boyd et al., 2004) with high lead levels persisting for up to several months. In such circumstances, partial lead pipe replacement by water utilities may actual increase liability, particularly if adverse effects on consumers were demonstrated, for example by observations of increased levels of blood lead. Recently, an information notice from the US CDC has highlighted an... 

Partial lead pipe replacement will not solve the problem in many cases and can even make matters worse, at least in the short term. 

In this example, it can be interpolated that an 82% reduction in plumbosolvency will be needed to achieve a 98% compliance level with the 10 pg/1 standard, the optimisation target in the UK. The model can also be used to predict the outcome of a partial lead pipe replacement campaign. Illustrative results are shown in Table 10.3. An overview of how the model is used is given in Figure 10.8. 

The model can predict the results of partial lead pipe replacement (where there is no galvanic corrosion component). 

Boyd, G.R., Shetty, P., Sandvig, A.M. and Pierson, G.I. (2004). Pb in tap water following simulated partial lead pipe replacement. Journal of Environmental Engineering. American Society of Civil Engineers, Washington DC, 130, 1188. 

Boyd, Glen R., Prasad Shettey, Anne M. Sandvig, et al. 2004. Pb in Tap Water Following Simulated Partial Lead Pipe Replacements. Journal of Environmental Engineering 130 1188-1197. 

The elements of the water safety plan should also focus on the issues related to lead pipe replacement, including particulate lead, and the potential galvanic eflects of partial lead service replacement. 

Requirements for partial replacement of utility-owned lead pipes may actually aggravate consumer lead exposure in some cases. 

The results indicate that the replacement of lead connection pipes has only been partially successful and that the replacement of lead pipes owned by home-owners is also required. 

Rabin (2008) relates how old municipal water systems used lead pipes to dehver water to homes. This was recognized as a public health threat in the 1800s, and in the early part of the twentieth century municipalities began to prohibit lead service lines. This movement was countered by the Lead Industry Association (LIA), which began a public campaign to commend the benefits of using lead pipes. Problems remain to this day, as the federal Lead and Copper Rule (LCR) requires water companies to initiate lead water pipe replacement when lead levels in water exceed 15 parts per billion (ppb). But the LCR allows water utilities to replace only the public portion of lead pipes. The private portion of these pipes, from the main service line to a house, can be left in place. Renner (2007) describes that when partial replacement is undertaken, that disturbance results in a rise in lead levels in water. Millions of homes in the U.S. have lead service lines as part of their water supply systems (McCartney 2010). 

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