Partial Lead Service Line Replacements Research Articles

Action Bias

When it comes to decision-making, a common paradigm holds that we are dominated by two modes of thought, namely rational and emotional. Rational thought is deliberate and reason-based (e.g., cost–benefit analysis), while emotional decisions are intuitive and influenced by context (i.e., from the gut). Our personal experiences shape our decisions, though there are many biases at play—such as status quo bias (tendency to keep things as-is), loss aversion bias (preference to avoid losses over making similar gains), and action bias. Action bias refers to our innate desire to take action. Part of this stems from the sense that it feels better to fail if you've tried something as opposed to failing without making an effort. Human nature seeks credit for positive actions and seeks to avoid blame for losses. Most people would rather go down swinging than watch the ball go by, and the same is true for water professionals, for whom taking action to solve problems is embedded in the very fabric of their nature. Yet, in situations where emotional perceptions dominate reasoned analysis, taking action may result in an outcome that's worse than if nothing is done at all. Our emotional activity around a negative outcome often outweighs its likelihood to the degree that it unduly influences our understanding and analysis. An example of action bias from the water industry may be partial lead service line replacements. As public water systems had no legal means to compel property owners to replace their lead service lines, many water utilities used to replace only that segment under their control. In these cases, the desire to fix the problem, to do something, was clear. However, the only way to remove lead contamination is to eliminate the lead pipes altogether, and studies have shown that partial lead pipe replacement can potentially disturb the system, stirring up particulate lead that would have remained dormant if left alone until the entire line could be replaced. Partial lead line replacements show how the water industry is susceptible to action bias—if something is wrong or broken or, worst of all, hurting someone, water professionals want to fix it, now. But we must always remember the interconnectedness of our water systems, and as much as we want to control them, remember that water systems are complex, and sudden changes can potentially ripple into unintended consequences. Partial lead line replacements seemed reasonable at first blush, but with more experience, full replacement became the preferred response. Quick action can be appropriate, especially when a community faces critical incidents—and those on the front lines need training and systems that support rapid decision making. However, there is often time for analysis and rational discussion to determine the best path forward. To avoid action bias, first, recognize that it exists. Relocate if your surroundings or context prevent you from making rational decisions. Put processes in place that ensure deliberation and encourage collaboration before action. Research the issue and ask colleagues for their opinions. Try to understand the outcomes of action, waiting for action, and no action at all. In short, you should check your gut, but check your head first. This month's Journal AWWA highlights the regulatory concerns facing water professionals as well as options for infrastructure funding, drought, and regional collaboration. Please consider submitting your technical, managerial, and financial experiences as a feature article for Journal AWWA and share your insights with water professionals around the world.

Lead and copper release from full and partially replaced harvested lead service lines: Impact of stagnation time prior to sampling and water quality

Partial lead service line replacement (PLSLR) results in the addition of a new galvanic connection and can increase lead concentrations at the tap. Focus has been given to minimizing lead release after PLSLR, but little information is available on the impact of lead remedial actions on copper concentrations, especially before passivation occurs. The impact of water quality (decreased chloride-to-sulfate mass ratio from 0.9 to 0.3; addition of orthoP; pH increase to 8.3) on lead and copper concentrations was investigated after stagnation (30 min–336 h) in a pipe rig comparing full lead service line (LSL), and two configurations of partial LSLs (Cu-Pb and Pb-Cu). Results show different trends for lead and copper: maximum lead concentrations were reached in 16 h while copper concentrations continued to increase over 336 h. Lead release rates were also the highest in the first 16 h of stagnation and were strongly impacted by water quality and the configuration of PLSLR (Cu-Pb vs Pb-Cu). Increasing the sampling flow rate from 5 to 15 LPM drastically increased the particulate lead release (78-fold) in Pb-Cu configurations; this effect was however not observed in 100% Pb or Cu-Pb configurations. High velocity flushing prior to 16 h stagnation decreased total Pb release by a factor of 12-fold for Cu-Pb, 1.6-fold for Pb-Cu and 2.0-fold for 100% Pb. Results support the definition of sampling protocols targeted for the detection of lead and copper sources and the proscription of flushing prior to sampling.

Lead Levels at the Tap and Consumer Exposure from Legacy and Recent Lead Service Line Replacements in Six Utilities.

Profile, regulatory, and investigative sampling were completed in six utilities to study the impact of partial and full lead service line replacements (LSLRs) on water lead levels (WLLs) and consumer's exposure. As compared to households with no replacement, lead release after partial LSLR (PLSLR) was generally greater in the short term (3-50 days), and comparable or lower in the medium (<2 years) and long-term (>2 years). This was mainly explained by insufficient time elapsed to stabilize scales after disturbances to the service line. One utility showed sustained lead release over 18 months after PLSLR. Moreover, the reduction in WLLs was small when analyzing results for the same households. As a comparison, full LSLR decreased WLLs drastically and immediately. The occurrence of low (0-5 μg/L) to high (≥50 μg/L) WLLs in the profiles varied between households and reflected the variability of exposure among households in the same system. Using this probability of occurrence, the distribution of WLLs of exposure was estimated for households with or without a PLSLR, and used to model young children blood lead levels (BLLs) for both groups of households. The range of modeled BLLs decreased slightly for households with PLSLR, but still overlapped the range estimated for households with no replacement. This analysis suggests that, in a system, PLSLRs do not reduce young children blood lead levels except in a fraction of households.

Impact of Corrosion Control on Biofilm Development in Simulated Partial Lead Service Line Replacements

Abstract Interaction of water quality, flow conditions, and the presence of lead and biofilm was examined in simulated partial lead service line replacement. Recirculating pipe loops were connected...

Short- and Long-Term Lead Release after Partial Lead Service Line Replacements in a Metropolitan Water Distribution System.

Thirty-three households were monitored in a full-scale water distribution system, to investigate the impact of recent (<2 yr) or old partial lead service line replacements (PLSLRs). Total and particulate lead concentrations were measured using repeat sampling over a period of 1-20 months. Point-of-entry filters were installed to capture sporadic release of particulate lead from the lead service lines (LSLs). Mean concentrations increased immediately after PLSLRs and erratic particulate lead spikes were observed over the 18 month post-PLSLR monitoring period. The mass of lead released during this time frame indicates the occurrence of galvanic corrosion and scale destabilization. System-wide, lead concentrations were however lower in households with PLSLRs as compared to those with no replacement, especially for old PLSLRs. Nonetheless, 61% of PLSLR samples still exceeded 10 μg/L, reflecting the importance of implementing full LSL replacement and efficient risk communication. Acute concentrations measured immediately after PLSLRs demonstrate the need for appropriate flushing procedures to prevent lead poisoning.

Comparison of three corrosion inhibitors in simulated partial lead service line replacements

Partial lead service line replacements (PLSLR) were simulated using five recirculating pipe loops treated with either zinc orthophosphate (1mg/L as P), orthophosphate (1mg/L as P) or sodium silicate (10mg/L). Two pipe loops served as ⿿inhibitor-free⿿ (Pb-Cu) and ⿿galvanic free⿿ (Pb-PVC) controls. Changes in water quality (CSMR [0.2 or 1], conductivity [⿿330mS/cm or ⿿560mS/cm], chlorine [1.4mg/L]) were not observed to provide a significant impact on lead or copper release, although galvanic corrosion was shown to be a driving factor. Generally, both orthophosphate and zinc orthophosphate provided better corrosion control for both total and dissolved lead (30min, 6h, 65h) and copper (30min, 6h), when compared to either the inhibitor-free control or the sodium silicate treated system. This work highlights the importance of understanding the complex interplay of corrosion inhibitors on particulate and dissolved species when considering both lead and copper.

In situ 2D maps of pH shifts across brass–lead galvanic joints using microelectrodes

Galvanic corrosion in drinking water distribution systems, such as conditions following partial lead service line replacement, can be a significant source of lead in tap water. The objective of this work was to measure the pH directly near metal surfaces using a novel experimental tool in order to understand the water chemistry at a lead-containing galvanic couple in drinking water. Specifically, pH microprofiles in the proximity of corroding metal surfaces were measured using a microelectrode to construct detailed in situ 2D spatial maps of the pH across a galvanic couple at 100 µm above the metal’s surface under flowing and stagnation conditions. The opposite pH trend was directly observed across the galvanic couple under flow and stagnation conditions. Water stagnation resulted in a pH at the anode (leaded solder) of 1.5 pH units lower than the bulk water pH (9.0) and as much as 2.5 pH units lower than the cathode (brass). These conditions can enhance lead release at the anode, which reflects different anodic–cathodic relationships of coupled metals primarily controlled by water flow. Most importantly, this work has demonstrated the ability to make real pH measurement at the surface of corroding metals using a novel microelectrode approach.

Evaluating the Effects of Full and Partial Lead Service Line Replacement on Lead Levels in Drinking Water.

Lead service line replacement (LSLR) is an important strategy for reducing lead exposure via drinking water, but jurisdictional issues can sometimes interfere with full replacement of the lead line. The effects of full and partial LSLR on lead levels were assessed using 5 × 1-L sample profiles collected at more than 100 single-unit residences. Profiles comprised four sequential standing samples (L1-L4) and a free-flowing sample (L5) drawn after a 5 min flush of the outlet. At 45 sites with full lead service lines, 90th percentile lead levels in standing samples ranged from 16.4 to 44.5 μg L(-1) (L1 and L4, respectively). In the free-flowing sample (L5), 90th percentile lead was 9.8 μg L(-1). Within 3 days, full LSLR had reduced L3-L5 lead levels by more than 50%, and within 1 month, lead levels were significantly lower in every liter of the sample profile. Conversely, partial LSLR more than doubled premises plumbing (L1, L2) lead release in the short term and did not reduce L1, L2 lead release in the long term. Even 6 months after partial LSLR, 27% of first-draw lead levels were greater than 15 μg L(-1) (the U.S. EPA action level), compared with 13% pre-replacement.

Long-Term Behavior of Simulated Partial Lead Service Line Replacements.

In this 48-month pilot study, long-term impacts of copper:lead galvanic connections on lead release to water were assessed without confounding differences in pipe exposure prehistory or disturbances arising from cutting lead pipe. Lead release was tracked from three lead service line configurations, including (1) 100% lead, (2) traditional partial replacement with 50% copper upstream of 50% lead, and (3) 50% lead upstream of 50% copper as a function of flow rate, connection types, and sampling methodologies. Elevated lead from galvanic corrosion worsened with time, with 140% more lead release from configurations representing traditional partial replacement configurations at 14 months compared to earlier data in the first 8 months. Even when sampled consistently at moderate flow rate (8 LPM) and collecting all water passing through service lines, conditions representing traditional partial service line configurations were significantly worse (≈40%) when compared to 100% lead pipe. If sampled at a high flow rate (32 LPM) and collecting 2 L samples from service lines, 100% of samples collected from traditional partial replacement configurations exceeded thresholds posing an acute health risk versus a 0% risk for samples from 100% lead pipe. Temporary removal of lead accumulations near Pb:Cu junctions and lead deposits from other downstream plastic pipes reduced risk of partial replacements relative to that observed for 100% lead. When typical brass compression couplings were used to connect prepassivated lead pipes, lead release spiked up to 10 times higher, confirming prior concerns raised at bench and field scale regarding adverse impacts of crevices and service line disturbances on lead release. To quantify semirandom particulate lead release from service lines in future research, whole-house filters have many advantages compared to other approaches.

Copper Deposition Corrosion Elevates Lead Release to Potable Water

Deposition corrosion has been identified as a possible factor contributing to consumer exposure to elevated lead in water after partial lead service line replacement. Dump‐and‐fill tests in two different waters yielded very different results; compared with the control, one water showed a substantial increase (approximately three times) in lead leaching, whereas the other showed little effect when copper was added to water contacting new lead pipes. These differences were consistent with expected trends; lead leaching increased as both the copper solubility in water and the amount of copper deposited on the lead pipe surface increased. Detailed analyses of lead pipes from laboratory studies and field tests in which lead was galvanically connected to copper using various commercial and laboratory connectors were consistent with pure metallic copper deposits on the pipe surface, especially near the galvanic junction with copper. This finding supports a significant deposition corrosion mechanism when copper and lead are galvanically connected.

Factors affecting lead release in sodium silicate-treated partial lead service line replacements

Water quality parameters affecting sodium silicate performance in partial lead service line replacements were examined using a fractional factorial experimental design and static pipe systems. An external copper wire was used to create a galvanic connection between a former lead service line and a new copper pipe. The pipe systems were filled with lab prepared water made to mimic real water quality. Water was changed on a three times per week basis. A 24−1 fractional factorial design was used to evaluate the impact of alkalinity (15 mg L−1 or 250 mg L−1 as CaCO3), nitrate (1 mg L−1 or 7 mg L−1 as N), natural organic matter (1 mg L−1 or 7 mg L−1 as dissolved organic carbon), and disinfectant type (1 mg L−1 chlorine or 3 mg L−1 monochloramine), resulting in eight treatment conditions. Fractional factorial analysis revealed that alkalinity, natural organic matter and monochloramine had a significant positive effect on galvanic current. Natural organic matter and monochloramine also had a significant positive effect with respect to both total and dissolved lead release. For the treatment conditions examined, 67–98% of the lead released through galvanic currents was stored as corrosion scales and predominantly comprised of particulate lead (96.1–99.9%) for all eight treatments. The use of monochloramine and the presence of natural organic matter (7 mg L−1) were not favourable for corrosion control in sodium silicate-treated partial lead service line replacements, although further studies would be required to characterize optimal water quality parameters for specific water quality types. For utilities operating with sodium silicate as a corrosion inhibitor, this work offers further evidence regarding the consideration of chlorine as a secondary disinfectant instead of monochloramine, as well as the value of controlling natural organic matter in distributed water.

High‐Velocity Household and Service Line Flushing Following LSL Replacement

Customer exposure to lead solely from drinking water may be greater in water containing particles than in water containing only soluble lead. Full and partial lead service line (LSL) replacements and other similar disturbances can potentially increase the release of lead‐containing particulates. Lead‐containing particles, loose scale, and other debris that can otherwise be transported to the customer tap can be removed by preventive measures like home water filters. This study investigated the use of high‐velocity flushing to preemptively dislodge and remove particulate lead following partial LSL replacements in order to at least reduce, and hopefully eliminate, the particles of lead reaching the consumer. Results suggest a potential benefit to flushing the service line and premise plumbing by opening taps inside the house but not from solely flushing the service line by opening hose bibs.

Fetal Death and Reduced Birth Rates Associated with Exposure to Lead-Contaminated Drinking Water

This ecologic study notes that fetal death rates (FDR) during the Washington DC drinking water "lead crisis" (2000-2004) peaked in 2001 when water lead levels (WLLs) were highest, and were minimized in 2004 after public health interventions were implemented to protect pregnant women. Changes in the DC FDR vs neighboring Baltimore City were correlated to DC WLL (R(2) = 0.72). Birth rates in DC also increased versus Baltimore City and versus the United States in 2004-2006, when consumers were protected from high WLLs. The increased births in DC neighborhoods comparing 2004 versus 2001 was correlated to the incidence of lead pipes (R(2) = 0.60). DC birth rates from 1999 to 2007 correlated with proxies for maternal blood lead including the geometric mean blood lead in DC children (R(2) = 0.68) and the incidence of lead poisoning in children under age 1.3 years (R(2) = 0.64). After public health protections were removed in 2006, DC FDR spiked in 2007-2009 versus 2004-2006 (p < 0.05), in a manner consistent with high WLL health risks to consumers arising from partial lead service line replacements, and DC FDR dropped to historically low levels in 2010-2011 after consumers were protected and the PSLR program was terminated. Re-evaluation of a historic construction-related miscarriage cluster in the USA Today Building (1987-1988), demonstrates that high WLLs from disturbed plumbing were a possible cause. Overall results are consistent with prior research linking increased lead exposure to higher incidence of miscarriages and fetal death, even at blood lead elevations (≈5 μg/dL) once considered relatively low.

Effect of connection methods on lead release from galvanic corrosion

Laboratory experiments were performed to evaluate the effect of galvanic corrosion on lead release following simulated partial lead service line replacements. Experiments were conducted in a recirculating flow mode with intermittent stagnation periods using aged lead pipes harvested from Washington, D.C. Lead pipe and copper tubing were connected by brass, brass dielectric, and plastic couplings; additional experiments were performed with plastic couplings and an external wire to connect the lead and copper. Lead release increased in the order of systems connected with plastic, plastic with external wires, brass dielectric, and brass couplings. The trends are consistent with galvanic reactions between lead and copper and between lead and brass. For systems with galvanic corrosion, the increased lead release was primarily in a particulate form. Increasing the chloride‐to‐sulfate mass ratio from 0.7 to 7 did not increase the dissolved or total lead release.

Impact of galvanic corrosion on lead release from aged lead service lines

Partial lead service line replacement (PLSLR) may be performed when tap water lead concentrations exceed the action level and in association with water main replacement or other maintenance. Partially replacing lead pipes with copper tubing can create a galvanic couple if the lead and copper are connected by a metal coupling, which can potentially enhance lead release by galvanic corrosion. The effect of two types of couplings, brass and plastic, on lead release after a simulated PLSLR was investigated in a set of laboratory-scale experiments. Experiments were conducted in a recirculation flow mode with intermittent stagnation periods using aged lead pipes harvested from Providence, RI. Release of both dissolved and particulate lead was higher for the brass-coupled systems than for the plastic-coupled systems, and galvanic corrosion was the primary cause of significant particulate lead release from the brass-coupled systems. For brass-coupled systems, longer stagnation times resulted in dramatically more release of particulate lead. Sampling of different volumes following stagnation showed that lead release for the brass-coupled systems was locally much higher in the region closest to the coupling. The impact of galvanic corrosion persisted for the six weeks of the experiment.

Galvanic corrosion after simulated small‐scale partial lead service line replacements

Partial lead service line replacement with copper pipe creates a galvanic cell that can accelerate lead corrosion. Bench‐scale experiments under stagnant water conditions of high chloride‐to‐sulfate mass ratio (CSMR) demonstrated that galvanic connections between lead pipe (new or aged) and copper pipe increased lead release into the water by 1.1 to 16 times, compared with a full length of lead pipe alone. The extent of galvanic attack was dependent on drinking water quality. Exposure to water of high CSMR increased lead release in the lead–copper rigs by 3 to 12 times, compared with a lessaggressive low CSMR water. Galvanic current also increased by 1.5 to 2 times when switching from low to high CSMR. The small area of lead pipe adjacent to the copper joint (&lt; 0.5 ft) dissipated 90–95% of the total galvanic current and accumulated a thick (1‐in.‐wide) layer of lead rust (i.e., a lead‐containing scale), which constituted a reservoir for semirandom particulate lead detachment into the water.