There's a lot of history under St. Louis streets and parks. There's a smelly but necessary present beneath them as well.

Both past and present down in St. Louis' nether regions get a close examination in the new KETC (Channel 9) documentary Under St. Louis, from the celebrated caves of the Lemp family to the construction of a new sewer project. (The latter might well be a nod to Insituform Technologies -- the sewer, water-main and industrial-pipe troubleshooting company that has underwritten the program.)

Some of the program is devoted to underground places that are fairly well-known to St. Louisans, like the underground portion of the Arch, the River Des Peres and Cherokee Cave. But other bits should be news to most folks, including a Cold War bomb shelter still stocked with supplies ranging from water to cotton swabs to crackers.

Though some of the subterranean journeys that host Jim Kirchherr takes during the program will make you crinkle your nose just imagining the odors (St. Louis' sewer system mixes storm runoff and waste, and the camera goes right where that particular sewer flows), the documentary is a perky and quirky 60-minute look at what's under your feet.

Bob Zahnweh, who produced and directed Under St. Louis, says that the genesis of the documentary came from flipping the premise of a previous KETC documentary on St. Louis as seen from the air on its head.

"We thought that a sequel that showed things from a different perspective might be a good idea," Zahnweh says. "Interest in the project and funding for it picked up, and eventually it picked up so much momentum that we got it done."

The sewers and the underground tourist sites that many still living in town may have visited were pretty obvious choices, but Zahnweh notes that he had to cast a wide net for suggestions about other marvels beneath St. Louis.

"We talked to a lot of people," says Zahnweh, "and found out who in town had access to these places."

Suggestions came from some unlikely places. It was, Zahnweh observes, a St. Louis police officer ("just a cop on the beat," he notes) who led him to the underground shelter in downtown St. Louis that was still stocked with Cold War survival supplies.

"There are still several caches of that material," Zahnweh says.

Downtown St. Louis seems to have the most intricate labyrinth of underground tunnels and features, if Under St. Louis is any indication. The documentary explores several subterranean passages in the downtown area, from the tunnel that's still used by the St. Louis Post-Dispatch for its newsprint deliveries to an intricate maze of tunnels under the main patch of government buildings downtown. Zahnweh and Kirchherr also explore the sewer tunnel that used to be Mill Creek. Located just south of downtown, the Mill Creek sewer system begins in the heart of Midtown and empties into the Mississippi River. Its opening in 1916 was celebrated with a formal dinner hosted by the mayor in the newly completed tunnel.

As with any documentary on a broad topic, some features were left out of the mix, including one of the favorite topics among South Side residents -- their own network of caves in that part of the city.

"Most of those caves were collapsed," Zahnweh notes, "or filled in for construction purposes." Zahnweh also admits to wanting to do more with other famous subterranean sites, including clay mines in what are now the Dogtown and Hill neighborhoods.

"I visited most of these locations myself before we filmed," Zahnweh says. His prime criterion, he adds, was whether "you'd be able to make a picture in total darkness."

Occasionally Zahnweh got lucky with inaccessible places such as the legendary Uhrig's Cave -- a late-19th-century city hot spot that boasted a beer garden and cabaret. The cave is filled with water now, but it was pumped eight years ago and a group of cave explorers took home video of what must have been the equivalent of McGurk's or the St. Louis Tap Room in its heyday.

Among the mysteries that Zahnweh couldn't solve with his documentary was that of the Civil War tunnels in Jefferson Barracks. "We looked and looked and couldn't find an entrance," he says.

It's a task for future St. Louis spelunkers, perhaps. And perhaps the subject of another documentary.