Effect of Flow Rate and Lead/Copper Pipe Sequence on Lead Release from Service Lines

Impact of treatment on Pb release from full and partially replaced harvested Lead Service Lines (LSLs)

“…However, these results were obtained using new lead pipes and/or fittings, and/or without realistic flow conditions or statistical replication. As predicted , lead release associated with galvanic corrosion can be highly dependent on stagnation time (Wang et al, 2012) and sampling flow rate (Cartier et al, 2012).…”

“…When specified, it can be vague with wording as "moderate flow rate" (Gouvernement du Qué bec, 2012) or even lower such as the <2LPM suggested by some investigators (Reiber et al, 1997). Such low values have been used during field sampling (McFadden et al, 2011;Sandvig et al, 2008) and may not detect risk of Pb spikes associated with particulate Pb release (Cartier et al, 2012) that can be associated with increase in blood lead (Deshommes and Pré vost, 2012).…”

“…Since copper is the main material for service line due to its longevity, resistance and its biostatic characteristics (Le Gouellec and Cornell, 2007), this metal is broadly used for partial/full LSL replacement in Canada and the US as observed on the field (Muylwyk et al, 2011;Sandvig et al, 2008). However, recent laboratory studies suggest that partial LSL replacement using copper (Cu) pipe is at best a marginal strategy for controlling Pb concentrations in tap water and may actually increase lead release in some circumstances Clark et al, 2011;Wang et al, 2012;Cartier et al, 2012). Based on field studies, partial LSL replacements yield no clear decrease in lead release at short term (2 months) (Sandvig et al, 2008;Swertfeger et al, 2011;Britton and Richards, 1981) and also provide no clear benefits over the long-term (18 months) (Muylwyk et al, 2011;Britton and Richards, 1981).…”

“…Galvanic corrosion between old lead and copper pipes Wang et al, 2012) is a potential explanation for unexplained long-term (>2 months) high concentrations following partial pipe replacements observed in the field (Sandvig et al, 2008;Britton and Richards, 1981). The presence of copper in water passing through the lead pipe has also been associated with higher lead release, possibly due to deposition corrosion or other mechanisms (Hu et al, 2012;Cartier et al, 2012;Triantafyllidou and Edwards, 2011) as well as crevice corrosion in the brass fitting used at the Pb/Cu junction (Clark et al, 2011). However, these results were obtained using new lead pipes and/or fittings, and/or without realistic flow conditions or statistical replication.…”

Distribution system water age can create premise plumbing corrosion hotspots

“…In the past, selection of Bworst case^sites has focused exclusively on identifying homes with the highest propensity to leach lead from plumbing based on a tier system of age and lead-bearing materials that are present in homes (Ferguson et al 1996;Broo et al 1997;Edwards et al 2001a, b;Rajaratnam et al 2002;Schock and Sandvig 2009;Turek et al 2011;Grace et al 2012). It has recently been acknowledged that other risk factors in homes can be of equal or greater importance including the length of lead service lines (Kuch and Wagner 1983;Cardew 2006;Cartier et al 2011), whether the service line has been disrupted by a partial replacement or other activities (Boyd et al 2004;Sandvig et al 2008;Triantafyllidou and Edwards 2011;Cartier et al 2012;Del Toral et al 2013), and even water use rates in the home Del Toral et al 2013). This research unambiguously demonstrates that the location of a home in a given water distribution system can also influence lead leaching, creating hotspots of corrosion that are associated with a greater incidence of childhood lead poisoning and even fetal death (Stith et al 2006;Renner 2006;Gronberg 2007;Edwards et al 2009;HDR 2011;Wang et al 2014a, b;Edwards 2014).…”