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municipalauthorities.org | 19 Satellite Imagery Finds Leaks in Small Rural Water Utility in Pennsylvania By Paul Gagliardo, MPH, PE, Gagliacqua Consulting, Karen Pollock, Senior Engineer, Systems Design Engineer- ing, Inc., and Aaron DeBalko, General Manager, Kline Township Municipal Authority ASTERRA uses satellite data to find potable water leaks underground. The company was founded in 2013 to commercialize the concept of locating subsurface, background potable water pipe leaks from space. Microwave radar is emitted from a satellite or any other airborne platform and used to detect the signature of wet soil underground with a potable water indication. This technology is similar to what is used to search for water on other planets such as Mars. L-band synthetic aperture radar (SAR) can be used for remote detection of underground soil moisture caused by things like drinking water leakage from an urban water system. Water sources such as leaking pipes, lakes, or swimming pools, reflect EM waves both below and above ground level. Every material has different electric properties, called the dielectric con- stant, creating an identifying marker. The SAR backscatter signal can dis- tinguish between these and identify potable water. Drinking water saturat- ed soil has a specific signature in SAR data that is isolated by ASTERRA to find leaking water pipes. SAR sensors placed on an elevated platform such as a satellite or an aircraft send EM waves at a known frequency towards an area of interest and read the EM backscatter from that area. The signals are compiled into an image. This includes backs- catter from water sources and other landmarks such as buildings, vegeta- tion, and topographical features of the area. For ASTERRA to identify the water related backscatter, all other signals (e.g., EM noise reflection) are filtered or removed from the scan. Since different water sources (e.g., drinking water, sewage, seas, lakes swim- ming pools, etc.) have different dielectric constants, it is possible to distinguish one from the other. Unwant- ed targets are filtered out or removed from the scan thus leaving only the signal backscat- tered from pipeline water leakages (the signal from drinking water mixed with soil). The entire process used by ASTERRA is propriety and patented. The result is a GIS-based map showing points of interest (POI) where there are likely potable water pipe leaks. This map of POI’s is then used to di- rect the boots-on-the-ground (BOTG) field inspections teams to confirm and pinpoint the leak location. The ASTERRA approach to finding leaks is analogous to a doctor performing triage on a patient to determine where the most acute problems are located. The entire water system is scanned and only the most likely leak locations are identified for further BOTG field inspection. This amounts to 5 -10% of the total length of pipe. The POI’s are the centroid of a buffer zone within which the field crews are to focus their attention. The buffer zone stretches up to 300-foot radius from the POI. All pipes within that buffer zone are inspected for leak noise using state-of-art acoustic devices. Typically, all of the listen- ing points (e.g. meters, valves, curb stops, hydrants, etc.) within that buff- er zone will be accessed to search for leak noises. Kline Township Municipal Authority (KTMA), in east-central Pennsylvania, utilized the ASTERRA services in June and July 2022. Figure 1 shows the district service area. They are a small rural utility with a non-revenue water (NRW) problem that had grown to 63% in calendar year 2021 and no pro- active leak detection program in place. The Authority’s consulting engineer firm, Systems Design Engineering, Inc. (SDE) brought the ASTERRA tech- nology to the KTMA Manager Aaron DeBalko’s attention after viewing an educational webinar presented by the National Rural Water Association (NWRA). Subsequently, KTMA received a grant from the Susquehanna River Basin Commission (SRBC) under their Consumptive Use Mitigation program to pay for the work. KTMA has a total of 2100 water ser- vice connections with a distribution system length of 25 miles. The system is comprised of 3 miles of 12-inch duc- Continued on page 36. Figure 1