In 2020, the City of League City received $49,580 from the Harris-Galveston Subsidence District’s Water Conservation Grant Program to fund a project that would utilize advanced technology to streamline field investigations, detect leaks, and repair waterlines, reducing local water loss by 9.1%. By using interferometric synthetic aperture radar (InSAR) technology, the City yielded 92,600 gallons per day in water loss savings, totaling $66,900 savings per year.

Total project cost: $187,000

Project details:

The City of League City serves over 100,000 people and has over 500 miles of utility main lines, with 34,000 retail metered connections. The City’s water loss percentage varied from 7-15 percent over the past 10 years. Improvements in the implementation of an Advanced Metering Infrastructure (AMI) system, the installation of strategically located auto-flushing devices and an aggressive water line replacement program in older neighborhoods contributed to a reduction in water loss percentages.

To further reduce water loss, the City requested funding from the District’s grant program to implement a project that utilized proprietary multispectral satellite imagery that was paired with acoustic leak detection field surveys. This project allowed the identification and repair of underground treated water leaks. This methodology has shown the potential to identify leaks faster and cheaper than traditional methods in other parts of Texas.

The City contracted with Utilis (who recently changed their name to ASTERRA) to complete four satellite fly-overs and imagery analyses. This investigation yielded 199 points of interest, which were verified by field inspectors who discovered and repaired a total of 47 leaks. The ability to locate and consolidate these areas of concern within the City’s 54 square mile boundaries and 500 plus miles pipe network allowed the City to focus resources where they would provide the highest percentage of success.

As a result of repairing the leaks on the utility side, there was a 9.1% reduction in real water loss which results in a savings of more than 92,000 gallons per day and $66,900 per year.

Lessons learned:

  • While the project focused solely on the utility side, the study did identify 22 leaks on the customer side. With an average retail water price of $5.50 per 1000 gallons, water loss amounts to $1,140 per year for each customer. This highlights future opportunities to provide that data to residents.
  • 93% of leaks were non-surfacing or not visible at the surface, highlighting the impact of using remote sensing technology to identify subsurface leaks.
  • Systems with a high percentage of PVC distribution piping should be aware that traditional acoustic leak detection methods do have limitations. Because of this, the team emphasized hiring the most qualified “boots on the ground” leak detection group to perform field evaluations.