Analyzing Lead Service Lines
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Analyzing Lead Service Lines
Operators should consider several approaches in creating accurate inventories
The deadline for the EPA’s Lead and Copper Rule Revisions is fast approaching. To be compliant, all public water systems have to meet a list of requirements, including the creation of a lead service line inventory by Oct. 16 of this year.
With limited time remaining to create your lead service line inventories, taking the right approach and working efficiently is a must. There are several different methods a utility can implement in creating accurate inventories
A review of municipal and plumbing codes, construction specifications, historical community records and interviews with water distribution staff and plumbers can help determine when lead service pipes were most likely installed and where they may still exist.
A records review provides a utility with a broad picture of their network without having to dig up any pipes or put any equipment inside the potable water piping. However, utility records can be unreliable or have gaps in data and you can’t always be sure if or when a customer has replaced their own supply pipes.
VISUAL EXAMINATION
Using a noninvasive method like visual, scratch or magnet tests allows a utility to verify the material of the service line, only requiring entry into the home or to engage residents to provide the data themselves.
While utility staff often perform this service, residents can identify private side service pipe materials by performing a scratch and/or magnet tests on the pipe entering the homes or building. A magnet will not stick to a lead or copper pipe but will stick to galvanized steel.
There is a risk that the visible portion of the pipe has been replaced with a different material than what is buried between the property and the external curb stop. Further, residents may not be properly trained in collecting data themselves, which may result in errors in records.
WATER ANALYSIS
Water-quality testing and sampling programs are well studied and are reasonably reliable at identifying hazardous levels of lead at the point of consumption along with other parameters that indicate corrosion or presence of lead materials. Testing for the presence of lead in the water is ultimately the largest indicator of potential health concerns.
Several sampling techniques have been developed to determine the presence and concentration of lead in drinking water. Many factors, including corrosion control practices, must be considered when developing a sampling program. Corrosion control practices that are intended to prevent lead leaching will adversely impact a utility’s ability to use this technique. Furthermore, basic water sampling techniques do not provide enough data to confidently identify the source of the lead. Sequential sampling attempts to localize the source through a series of water samples; however, the time and resources required to execute it may not be suitable at scale.
MECHANICAL EXCAVATION OR VACUUM EXCAVATION
Excavation exposes the surface of a buried portion of the pipe, providing high confidence of the material at the point of excavation. With mechanical excavation, the material of the entire length of pipe can be determined with high confidence. Vacuum excavation exposes 6 to 12 inches of the service line for further visual inspection.
Excavation or potholing is costly and a major disruption to customers, as reinstating driveways or landscaping can be onerous and expensive. Furthermore, in the case of vacuum excavation, this is a snapshot of the pipe and is not always representative of the primary material of the supply line.
MODELING
Models are able to consume large amounts of data in a relatively short amount of time, improving the speed of records review tasks. The model data sources (utility records, public data and proprietary data sources) leverage several parameters such as property age, demographics, etc., as well as in-field validations and machine learning algorithms to provide water companies with an estimate as to which supply lines likely contain lead. Further, modeling can provide the utility with information about the probability of whether a pipe they do not have information on is lead or not with no disruption to customers.
However, modeling is still an estimate of the probability of lead being present. It can direct utilities where to test for lead, but it is not a substitute for the actual in-field validation. Inspection will still be required when modeling is incorporated in a lead service line inventory verification program. The inspections provide feedback on the accuracy of the model. One or more inspection methods may be required when using modeling.
ACOUSTIC WAVE ANALYSIS
Acoustic wave analysis is simple, nonintrusive (nothing in the service line), easy to deploy and can inspect the pipe within minutes without disrupting service. Two acoustic sensors are used to “bracket” the portion of the supply line to be screened for lead, with one placed on the external curb stop or meter box and another sensor placed on the internal shut-off valve. In some cases, the second sensor can be placed outside a customer’s residence, such as on an external customer meter near the dwelling wall or hose bib, eliminating the need for operators to enter the home. An acoustic signal is sent through the pipe and recorded and analyzed by commercial software and analytics, such as Echologics’ PipeScreen Service Line Analyzer. The examination of multiple acoustic properties ensures the robustness of acoustic wave analysis.
While advanced acoustic digital signal processing is a proven technology used in the field for over a decade, the application of this technique in determining pipe material is still relatively new.
Water utilities can reference the EPA’s guidance for developing and maintaining a service line inventory.