The Lead Pipe Problem (and Opportunity)

A systemic lack of documentation detailing where lead service lines (LSLs) are used to deliver water to homes is a challenge that plagues many cities across North America. This is particularly acute in the eastern Provinces and mid-Western States of Canada and the U.S.  

In many cities, lead services were still the default material type used through the 1950’s, and in some cases into the 1980’s. Furthermore, incomplete records of replaced services have left thousands of properties with completely unknown pipe material. The EPA alone estimates the population of LSLs in the U.S. to be near 10M. On a utility level, the scale of infrastructure that must be located, inspected, documented, and replaced is truly monumental.

On top of a lack of documentation, homeowners are often responsible to replace the private side of the service themselves through independent contracting, while the utility must replace the public side. Site inspections which may require entering private residences or excavation to determine pipe materials are often difficult to coordinate, thus increasing cost.

Legacy Approaches

To address this issue, in 2021, the US Environmental Protection Agency revised its policies for utilities and community water systems so that they must, effective October 2024, have initial steps in place to develop a complete inventory of Lead Service Lines (LSLs). The Lead and Copper Rule Improvements (2023) added further intensity to these efforts, requiring every lead service to be located, and removed, over the next decade.

So how would utilities try to establish the material type of a service, or understand if it is an LSL? There are several methodologies currently being used to identify LSL’s which we will briefly review.

  • The first source would be historical records, if they exist, on where lead is and is not.
  • The second would be customer driven data, such as inspection reports, insurance, or any other documentation provided by a homeowner which could validate the existence of a lead service.
  • Another method is water quality sampling, where higher concentrations of lead could indicate a lead service, but could also be due to other sources, such as lead-brass fixtures like faucets and valves or lead soldered to join pipes pre-1990.
  • If pipe is exposed, the natural softness and pliability of lead makes it easy to scratch, and it’s non-magnetic, but then again copper is also non-magnetic.
  • Camera testing could be used to attempt to visually identify lead services but is difficult and requires access to insert equipment into the service line.
  • Data science methods using historical geography-based data is a fascinating approach to predict the location of lead services but is inherently unreliable unless it’s founded on a solid data base to train learning algorithms. It could be used more as a higher-level search tool but wouldn’t likely operate on a case-by-case basis.
  • Finally, you can always just excavate down to the buried pipe and see if it’s lead, whether by scratch test or visual inspection.

Each of these options poses one or several problems, whether it be expense, intrusiveness, reliability, or consistency in some cases.

Time for a Novel Approach

By applying acoustic theory to water service lead identification, we are effectively trying to use the different physical properties of the different service material types, to manifest themselves by acting as a medium for transporting acoustic waves. As you can imagine, a peice of copper service (light, thin-walled, ringy) will act very differently to a piece of lead service (heavy, thick-walled, absorbant).

There are different ways that could theoretically be used to determine material:

  • Velocity testing: Measure the speed of structural waves. Requires two points of measurement, so access to the inside of the residence is required. Would be difficult to perform an assessment if the pipe has multiple materials
  • Frequency spectrum analysis (FSA): Excite service at the fundamental resonant frequencies and measure the responses.
FIG1: Leadfinder1000 early prototype

Our approach leverages frequency spectrum analysis, which when applied correctly allows us to avoid two direct points of measurement on the service. Therefore, no entry is required into the home, a huge benefit to the utility for approaching this challenge with scale. Executed through a shaker and deployment of a series of sensors in proximity to the service, will be able to capture the representative characteristics of the service type below each sensor. We believe that our methodology will determine the presence and extent of mixed services, for example a stranded piece of lead between two pieces of copper.

One of our testing protocols involves shaking the service via the curb stop a predetermined frequency, known to excite a response from either the copper, or the lead, based on emprical data collected in the field. The excited frequency transmits down the service and into the soil, such that a series of sensors can capture the representative response along the service. Applying mathematical techniques to process the data, such as a time averaged Fast Fourier Transform (FFT), we are able to see a profile of the signal response at a point in question, for our target frequencies.

FIG2: Time Average FFT of Lead and Copper

Initial testing makes us confident that we are able to determine the material make up of services along the water main to private home, including the presence of mixed material types.

Acoustics in the broader infrastructure technology market

The application of acoustic principles for determining the condition of a pipeline (or other) asset, or for determining the presence of location of a leak on a pipeline (or other) asset, has become common practice wihtin the municipal water sector. These principles, and the exciters (noise sources) and sensors (signal receivers) that manefest in products and applications, have been applied by acoustic engineers and product companies on a variety of applications across a diverse set of sectors, including oil & gas, mining, transport, civil, aviation, and many more. Our SonicFinder1000 product is applying similar principles to the challenge of locating buried, un-marked plastic water and gas services.


The Plastic Pipe Problem (and Opportunity)

When plastics emerged as a key material for construction and infrastructure projects in the aftermath of the Second World War, no one was quite ready for how quickly it would become a dominant material type for pipeline infrastructure. Two variants, PVC and HDPE, were particularly well suited for pipeline construction, and were first crafted into water and gas mains in the 1950s. Many thousands of miles of pipeline were installed in the growth years of 1950s and 1960s.  

However, only in the late 1960’s did utilities realize that they had a problem – they could no longer locate the metallic water or gas mains using magnetic locators. They were effectively blind to where they had installed these plastic pipeline assets, and in the late 1960s they started to lay tracer wire on top of the plastic pipe for locating purposes. While effective, early tracer wire had corrosion issues which weren’t addressed for almost a decade.

The net result is that today many utilities operate hundreds of miles of plastic gas and water mains that create locating challenges every time a utility locate is required. For gas operators, a faulty or mis-located utility could cause serious damage, bodily harm, and risk to their license to operate.

Legacy Approaches

Industry has been developing novel technologies to try and locate un-marked buried plastic pipeline for years, and some progress has been made. The most popular categories of solutions are as follows:

  • Ground Penetrating Radar: Typically mounted on a cart due to the size and weight of the technology, GPR is quite affective in the right conditions. Unfortunately, it has limitations in many soil types, potentially upwards of 70% of the common soils found in N.A. False positives can result from an incorrect measurement in poor soil conditions.
  • (Electronic) Witching Rods: The concepts of witching have long been in the back pocket of many a locator. Efforts to digitalize and make into a product have been received by a skeptical locating community.
  • Acoustic Devices: Come in a few shapes and sizes, from devices that impart a tapping force onto the pipeline directly, and listen along the pipe, to devices that generate a sound and receive a bounce-back signal all in the same enclosure, measuring location and depth. Another solution requires positioning a sensor directly into the gas stream and measuring the effect on gas molecules. The range of intrusiveness varies, and so does efficacy.

Time for a Novel Approach

FIG1. Equipment Required

By reframing and simplifying acoustic theories to plastic pipeline locating, we believe that a new way to locate is possible. Here’s how:

  • Charge up your field replaceable and fully rechargeable standard batteries for the SF1000 the night before you head out locating.

  • Once onsite, access the pipeline asset via an exposed point – typically the gas meter (if gas main) or a hydrant (if water main). A variety of access points exist depending on the utility, and the pipeline you are locating. Connect the receiver (the listening device) on the gas service.
  • FIG2. SonicFinder1000 display

    Once paired with the transmitter, you move toward the buried asset with the portable transmitter which creates an acoustic condition. Once the transmitter hovers over the service of interest, the device will indicate that you are in fact locating the pipe via the transfer of the noise generated back to the listening device.

  • Mark out the buried pipe asset in a series of passes, and de-mobilize to the next site.

[Schematic from the brochure, SF1000 with parts labelled]

Our Advantages

The SonicFinder1000 is a step change towards efficient, and consistent, location of plastic pipes. Some highlights include:

  • Works in a broad variety of soils, making it much more versatile than the ground penetrating radar carts
  • Proven to be reliably accurate
  • Acoustic technology allows for process signal filtering and frequency targeting
  • Advanced version of our technology will automatically create a virtual asset in a GIS platform (e.g. Esri)

Simply put, it works.