How low can you go? Up to 140 feet underground, apparently — if you want to see the progress on San Antonio Water System’s massive sewer replacement project on the city’s Southwest Side.

SAWS Engineering & Construction VP Andrea Beymer, left, and President/CEO Robert R. Puente were among the utility’s leaders to descend into the remarkable maze of shafts and passageways near Joint Base San Antonio-Lackland for a top-to-bottom view of the endeavor.

In all, five miles of tunnels will be constructed for the new 104-inch-diameter sewer main, to avoid disrupting traffic and military activity on the surface.

Construction on the $167 million pipeline — the most costly and complex sewer project in San Antonio’s history — is expected to be completed in 2023.