Hundreds of billions of dollars will have to be spent to replace pipe mains in the next 25 years. In the US, more than 200,000 water main breaks occur each year. These leaks result in the loss of over two trillion gallons of treated drinking water per year.
These losses result in many negative impacts to utilities. Surfacing water leaks and large main breaks are highly visible and very costly. Non-surfacing leaks can have a larger impact on total real water loss because they can go unnoticed for months or years. Utility managers are already responding to known surfaced leaks by responding to customer reported work orders.
The City of New Braunfels is located in the greater San Antonio area of Texas. The municipal water system consists of 573 miles of water mains. NBU serves a population of 84,200 through 39,060 service connections. An average of 13.3 million gallons per day (MGD) is supplied to the system with a net sales volume of 10.9 MGD. This equates to a non-revenue water (NRW) volume of 2.4 MGD, or 18%. NBU has a goal to reduce NRW and has deployed various technologies during the previous five years with limited success.
Starting in 2018, New Braunfels Utilities (NBU) deployed a new program using the ASTERRA (formerly Utilis) satellite radar remote survey product, Recover, to pre-locate likely pipe leaking locations. Satellite remote sensing collects data which can be analyzed to identify hidden leak locations with accuracy and at low cost. The analysis detects leak signals along the pipeline route and highlights high leak probability clusters allowing for efficient field crew deployment.
ASTERRA’s Recover provides a GIS-based map of Points of Interest (POI) or Likely leaking Locations (LLL) for field leak detection boots-on-the-ground (BOTG) teams to physically inspect. Leaks are not distributed evenly throughout a system. There are leak clusters or areas of higher leak densities that the ASTERRA technology can detect. The POI/LLL map directs the BOTG crews to those areas that will most likely have leaks, thus increasing the efficiency of the crews. A total of 229 leaks were identified during 56 days of BOTG field inspection work. 4.1 leaks were found per crew day and 1.3 leaks were found per mile physically inspected.
Of the 229 leaks identified 128 were customer side and 101 were NBU side. 143 of the 229 leaks were deemed to have a quantifiable leak flow rate. Altogether it was calculated that total water loss due to these leaks was 50.1 million gallons. Of this total 1.4 MG was due to customer side leaks, leaving a total of 48.7 MG of NBU side real water losses. This equates to a lost value to NBU of $220,120 based on a cost of water production of $4.52 per 1000 gallons.
The work performed by NBU is significant because of its detail and scope. NBU has inspected all the POIs identified by ASTERRA in four distinct surveys. Each survey has covered the entirety of the NBU service area, thus the same area has been inspected four times. NBU has estimated the flow rate and duration of all the leaks found. This information along with details on historical traditional BOTG inspections with temporary acoustic monitoring have allowed the calculation of performance and value metrics such as cost per crew day and cost per leak found. This, in turn, can be used to calculate value proposition of program, reduction of NRW, value of lost water, ROI and simple payback.
The full case study can be found in AWWA Opflow here: https://asterra.io/resources/satellite-data-complement-traditional-leak-detection/
Editor's Note: Scranton Gillette Communications and the SGC Water Group are not liable for the accuracy, efficacy and validity of the claims made in this piece. The views expressed in this content do not reflect the position of the editorial teams of Water & Wastes Digest, Water Quality Products and Storm Water Solutions.
