The Southern Environmental Law Center report identifies potential risks including flooding, sinkholes and ground subsidence. It does not say the project will cause those problems. The environmental group is calling for more transparency about the project’s risks and safeguards as work moves forward.

The report focuses on karst, a type of terrain where groundwater dissolves limestone and can create underground channels and cavities. It describes voids larger than 13 feet and says portions of the proposed route would cross areas with well-developed karst, from downtown toward the airport.

“Some of those conditions can’t simply be avoided,” said Trey Bussey, a senior attorney with the center. He said the tunnel would pass through areas with karst features.

The report also asks who would be responsible for addressing damage if problems arise. “If there is a sinkhole in our streets, who fixes that? Who pays for that?” Bussey said.

It points to known contamination near the route, including the former Aladdin Industries site on Murfreesboro Pike. The report raises concerns about possible effects but does not establish that tunneling would spread contamination or damage groundwater.

The Boring Company announced the Music City Loop in July 2025. Its 2025 environmental assessment concluded that the project was not expected to harm the environment or disrupt city operations. The company did not respond to a request for comment on the new report.

The findings put attention on what protections, monitoring and financial responsibilities would apply to a major underground project in Nashville’s distinctive geology. The report calls for a clearer account of how potential risks would be managed.