AI & Cross Bores: How PG&E Leverages AI in Sewer Cross Bore Safety Program

For more than 40 years, horizontal directional drilling (HDD) has been a valuable trenchless technology for installing small-diameter underground utilities in densely populated areas. But with that utility comes risk — specifically, the accidental conflict with and damage to existing underground infrastructure known as a "cross bore." Side sewer laterals are among the primary types of utilities at risk, and the consequences of an undetected cross bore can be severe.

Over the past decade, most gas utilities have dedicated significant resources to CCTV sewer inspection programs to address cross bore safety. Pacific Gas and Electric (PG&E), headquartered in California, is one of the leaders in this space — and it is now leveraging artificial intelligence to take that program to the next level.

PG&E's Cross Bore Mitigation Program

PG&E owns approximately 43,700 miles of gas distribution facilities across California. Since launching its Cross Bore Mitigation Program in 2013, the utility has completed over 250,000 sewer inspections — averaging more than 28,000 inspections per year across the state for nine consecutive years.

Aaron Rezendez, manager of Gas R&D, Utility Partnerships & Innovation at PG&E, describes the program's mission:

"The program uses video camera inspections to verify that no damage has occurred to sewer lines when using trenchless construction methods. The goal of the program is to identify cross bores by completing inspections of potential conflict locations and repairing all occurrences as they are discovered."

Cross bore conflicts have been found in just under 0.3% of sewers inspected — a seemingly small percentage that nonetheless represents a meaningful safety risk at scale. The CCTV data generated by the program is staggering: more than 30,000 hours of video footage, exceeding 22.5 TB of storage — roughly equivalent to the entire Netflix catalog. At 40 hours per week, it would take a single reviewer more than 15 years to watch it all.

Introducing AI-Powered Cross Bore Safety Audits

SewerAI is a Walnut Creek, California-based technology company that has been applying AI computer vision and cloud computing to sewer inspection since 2019. Its AutoCode tool automatically detects conditions in sewer inspection videos at tens of thousands of feet per hour — dramatically accelerating what was previously a labor-intensive manual review process.

Since late 2022, SewerAI has partnered with PG&E on a multi-year contract to conduct AI-powered "cross bore safety audits" of approximately 10,000 lateral CCTV inspections per year, with a focus on PG&E's projects in Northern California. The audits work as follows:

• Video footage from lateral CCTV inspections is analyzed using SewerAI's AutoCode tool for signs of potential cross bore hazards.
• Automated alerts are generated through SewerAI's PIONEER cloud platform, notifying project stakeholders of any identified issues.
• The project is carried out in coordination with four different sewer services contractors.

The partnership also modernized PG&E's data management infrastructure. Prior to working with SewerAI, contractors were required to burn DVDs of all inspections for storage at a physical PG&E location. SewerAI helped the utility transition to cloud-based storage, active alerts, and AI-powered analysis — a significant operational upgrade.

Proven Results: 100% Detection, 70% Time Savings

The performance of SewerAI's AI-powered approach has been validated through rigorous testing. In January 2021, SewerAI analyzed a dataset of 1,040 lateral inspection videos — including 40 videos with known cross bores — with a total playback time of 64 hours. The results were compelling:

• 100% detection rate: The AI tool, combined with data technician review, correctly identified all 40 known cross bores.
• 70% reduction in review time: AI reduced the review time from 64 hours to just 19 hours — approximately 30% of the original time required.

These results demonstrate that AI-assisted review not only matches human accuracy on critical safety detections — it dramatically reduces the time and cost required to achieve it.

A Mission-Driven Technology Partnership

SewerAI CEO Matt Rosenthal underscores the broader purpose behind the technology:

"Our goal is to help our clients mitigate risks and save lives. By combining the latest advances in AI and machine learning with expert knowledge of sewer infrastructure, we're able to provide insights that can make a real difference in people's lives."

The PG&E partnership is a strong example of how AI is moving from a theoretical promise to a practical, life-safety tool in the infrastructure sector. As utilities continue to manage aging sewer systems and growing volumes of inspection data, AI-powered platforms like SewerAI's offer a scalable path forward — one that keeps communities safer while making inspection programs more efficient and cost-effective.

This article was originally published in Trenchless Technology by Eric Sullivan, Director of Business Development at SewerAI, on May 17, 2023.