Lead Service Line Replacement Research Articles

Get the Lead Out!

To protect public health, many proactive water utilities are committed to removing their lead service lines. The Lansing (Mich.) Board of Water and Light takes a trenchless approach to lead service line replacement.

How Not to Get the Lead Out—Lead Service Line Replacement Will Not Solve Our Drinking Water Crisis

Since the water crisis erupted in Flint, Michigan, over lead in the water, there have been numerous calls to replace lead pipes used to bring water into the home. This is likely to do little, if anything, to reduce the detection of lead in drinking water under EPA sampling protocols. The problem is that the standard 1-l sample draws only from the first 10 to 22 ft of the pipe, not enough to reach the service line. The lead most likely comes from interior plumbing. Unless we find the actual sources of the lead, we may be in the same crisis position years from now after spending billions of dollars.

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.

Role of the water main in lead service line replacement: A utility case study

To understand the role of water mains in lead and iron release following lead service line (LSL) replacement, samples were collected from the tap water of 28 homes in Halifax, N.S., after a minimum 6‐h stagnation. In full replacements, average lead concentrations in service lines connected to cast‐iron mains with three different maintenance conditions—pigged, pigged and lined, and not pigged or lined—were 31.5±11.0, 3.3±2.3, and 3.7±2.7 μg/L, respectively, compared with 0.58±0.2 μg/L for ductile‐iron mains. In partial replacements, average lead concentrations were 63.09±30.9, 14.60±2.9, and 6.82±3.3 μg/L, respectively, for the three cast‐iron main conditions, compared with 8.5±3.1 μg/L for ductile‐iron mains. Adsorption of lead on iron corrosion scales dissolved or dislodged from tuberculated mains could account for the higher lead release observed. In this study, full replacement LSLs connected to ductile‐iron mains had the lowest lead concentrations.

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.

Monitoring and Control Experience Under the Lead and Copper Rule

Monitoring requirements under the Lead and Copper Rule took effect in 1992 for large and medium‐size public water suppliers and will take effect in 1993 for small systems. Starting in the mid‐1980s, the Newport News Waterworks began planning for compliance with lower tap water limits for lead and copper. A lead service line replacement program has been completed, corrosion inhibition treatment through the use of zinc orthophosphate has been optimized to limit lead, and at‐the‐tap monitoring has been in place since 1988. Results obtained from Lead and Copper Rule compliance monitoring indicate these efforts have contributed to compliance with the action levels for lead and copper under the rule and have reduced lead levels at customers' taps.

Complying With the New Lead and Copper Rule

Public education is an important element of the US Environmental Protection Agency's (USEPA's) new Lead and Copper Rule. In addition, some systems may be required to replace lead service lines to stop lead from leaching into drinking water. The article discusses public education, including the actual words that EPA dictates must be used in the public notices about lead. The article also discusses lead service line replacement, including the EPA's definition of who “controls” a service line and is therefore responsible for replacing it. This is the fourth in a series of articles about the lead and copper rule; the other articles in the series appeared in the August, September, and October 1991 issues of Opflow.

First Step to Lead Rule Compliance: Monitoring

Monitoring for lead, copper, and other water quality constituents is the first action a utility must take to comply with the new Lead and Copper Rule. Results of monitoring determine additional actions the utility must take to comply with the rule, such as corrosion control, source water treatment, public education, and lead service line replacement. This article details monitoring requirements; tables give the monitoring schedule for lead and copper for systems of various size, sampling requirements, targeted sampling site criteria for community water systems, a water quality monitoring schedule for constituents other than lead and copper, tap sampling requirements for constituents other than lead and copper, and approved analytic methods. This is the second in a series of articles on the lead and copper rule; the other articles in the series appeared in the August, October, and November 1991 issues of Opflow.