Lead pipe replacement

Measures for individual houses consist of lead pipe replacement and flushing before drawing water for eonsumption. The effect of the first measure ean be established using 30-minute stagnation-time sampling and proportional sampling. To assess the efifeetiveness of flushing, the fully flushed protocol can be applied. 

Lead pipe Replacement with copper pipe... 

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... 

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. 

As an alternative to random daytime sampling, but preferably as a supplementary monitoring method, stagnation sampling at selected properties can provide useful information on the effectiveness of dosing ortho-phosphate for reducing plumbosolvency. This approach is not relevant if total lead pipe replacement is undertaken as the sole corrective measure. 

Lead pipe replacement and other engineering options... 

Engineering options for lead pipe replacement or modification... 

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. 

Attempts at total lead pipe replacement that include internal domestic lead pipes have failed because of a lack of cooperation from home-owners. 

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). 

Units costs are likely to range from 500 to 2,000 per domestic lead pipe replaced, depending on pipe lengths, ground conditions, re-instatement of garden frontages and internal re-decoration. 

Unit costs of total lead pipe replacement... 

Units costs are therefore likely to range from 1,000 to 4,000 for total lead pipe replacement per property. 

Therefore, the cost of total lead pipe replacement will be between 15 M and 60 M. 

Total lead pipe replacement assuming a cost of 15 M spread over 10 years... 

Dosing ortho-phosphate to control plumbosolvency costs considerable less than lead pipe replacement. 

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. 

A1.3 Den Haag (The Hague) (NL) pH elevation and lead pipe replacement... 

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. 

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