Filling Information Gaps through
Research
While there has been extensive research on the risks posed by lead, the sources of exposure, and the effectiveness of various interventions to reduce exposure, there is still much to learn. The following are the main information gaps that need to be filled to support communities and utilities seeking to accelerate lead service line (LSL) replacement. The list will likely grow as communities identify additional needs. The Collaborative encourages you to make suggestions by sending an email to feedback@lslr-collaborative.org.
1. Tools to identify LSLs
An essential step in accelerating LSL replacement is to find an efficient and effective method to identify LSLs. While most utilities have a rough estimate of the number and location of LSLs to scope out a program and begin systematic replacement, they will eventually need a complete and accurate service line material inventory. Even the most careful utilities have gaps in their inventory and are often surprised once they start digging.
Keep in mind, most of these lines were installed 50 to 100 years ago and records are incomplete, especially for the service lines on private property. The problem is particularly difficult when a utility expands into adjacent communities or takes over a struggling utility since records may be lost in these transitions.
At this time, many utilities do not have a complete and current inventory of the pipe material used for every service line in their system, particularly for the portion of the service line on private property. There can also be difficulty understanding where lead goosenecks are installed. Because the gooseneck is completely inaccessible without excavation (often under a street) there is a need for a technological solution to confirm where goosenecks are located. Having as complete an inventory as possible of service line materials improves the effectiveness and efficiency of community lead service line replacement initiatives.
Keep in mind, most of these lines were installed 50 to 100 years ago and records are incomplete, especially for the service lines on private property. The problem is particularly difficult when a utility expands into adjacent communities or takes over a struggling utility since records may be lost in these transitions.
At this time, many utilities do not have a complete and current inventory of the pipe material used for every service line in their system, particularly for the portion of the service line on private property. There can also be difficulty understanding where lead goosenecks are installed. Because the gooseneck is completely inaccessible without excavation (often under a street) there is a need for a technological solution to confirm where goosenecks are located. Having as complete an inventory as possible of service line materials improves the effectiveness and efficiency of community lead service line replacement initiatives.
The Best Practices part of this toolkit provides utilities with a process to identify LSLs through a record review and on-site inspections as opportunities arise. The toolkit also shares models of communities that have lead the way. Those leading communities have found that they can be reasonably confident which properties do not have LSLs based on age of structure or size of the service line, but they are less confident in other situations.
A Water Research Foundation (WRF) project, completed in 1995, explored service line material identification techniques. This research found that various techniques and technologies were able to detect underground pipes and differentiate materials. However, no technologies were able to remotely detect and differentiate service line materials; direct contact with the line was essential. Advancements in technology may change this situation.
In 2016 WRF funded two projects that will evaluate the available technologies to identify LSLs and complete multiple case studies to highlight the techniques utilities currently use to identify LSLs.
2. Identifying LSL disturbances likely to release lead into drinking water
Research by DelToral into partial LSL replacement found increased release of lead particulate into drinking water due to disturbance of lead service lines. These particulates may enter directly into the water people drink or become trapped in the faucet aerator and release lead over time.
A partial LSL replacement is a significant disturbance of the line. There are other sources of physical disturbance for which the likely impact of lead release is not clear. Potential disturbances range from removal of a nearby underground utility line, earthquake, road repair and reconstruction, and large truck traffic over the service line.
Without this information, communities have difficulty setting the best long-term priorities and designing the most effective program to replace LSLs.
In addition, water sampling may or not detect these disturbances. Even when it does detect it, making the link back to the cause is more difficult. If disturbance is an important contributor to lead release then current water sample protocols could provide a false sense of assurance to consumers that they are protected from lead in drinking water.
A partial LSL replacement is a significant disturbance of the line. There are other sources of physical disturbance for which the likely impact of lead release is not clear. Potential disturbances range from removal of a nearby underground utility line, earthquake, road repair and reconstruction, and large truck traffic over the service line.
Without this information, communities have difficulty setting the best long-term priorities and designing the most effective program to replace LSLs.
In addition, water sampling may or not detect these disturbances. Even when it does detect it, making the link back to the cause is more difficult. If disturbance is an important contributor to lead release then current water sample protocols could provide a false sense of assurance to consumers that they are protected from lead in drinking water.
3. Evaluation of effectiveness of flushing
Replacement of an LSL is likely to be accompanied by release of particulate lead, whether from the severing of the service or lead scale separating from pipe surface due to disturbance, or both. Utilities often clear lead from internal building plumbing by flushing the pipes through existing faucets. An ideal flushing technique would accomplish this without the risk of introducing lead into the building plumbing.
Some construction techniques strive to protect internal building plumbing by turning off the meter outlet valve early in the construction process. This approach may prevent backflow and scouring of internal plumbing with its associated release of particulate lead.
Research into additional techniques would be useful. The research should compare the following:
Some construction techniques strive to protect internal building plumbing by turning off the meter outlet valve early in the construction process. This approach may prevent backflow and scouring of internal plumbing with its associated release of particulate lead.
Research into additional techniques would be useful. The research should compare the following:
- Effectiveness of the “whole house flushing” technique used by Cornwell, et al where screens/aerators are removed, water is run at high velocity starting at the lowest level in the building and working to upper floors through house. Duration of this type of flushing is a current WRF project.
- Option of removing the water meter while flushing so that higher flow velocities be reached?
- Reversing the direction of the initial flush so that the water supplied from another service line flows from the house toward the meter and is directed to waste, e.g. out a nearby window or into sink drain.
4. Evaluation of releases from undisturbed LSLs to provide baseline
One of the perceived limitations of sampling is that it does not capture the random release of particles from undisturbed LSLs. This limitation is used as “reason” not to sample at all and to discount results of samples that are collected.
Research could separate out flushing for dissolved lead (displacement flushing) versus removal of particulate lead after disturbance (high volume whole house flushing). This research would clarify our suggested replacement practices.
Research could separate out flushing for dissolved lead (displacement flushing) versus removal of particulate lead after disturbance (high volume whole house flushing). This research would clarify our suggested replacement practices.