"I opened it up and there was one bag, sitting on the bottom of both cans," he says. Normally, Treppel explains, there are two, three or even four bags in each can.
Treppel, who's involved in a lawsuit against a Canadian pharmaceutical firm, was suspicious and hired a private investigator.
Camped out behind a fence, Treppel's private eye shot a video, later obtained by BusinessWeek magazine, in which two men drive up to Treppel's garbage cans, take his garbage out, substitute other bags, then drive away.
Asked if discovering the spying made him worry about his family Treppel says "Sure, yeah. Because you don't know what they're after, don't know what else they took."
If you think taking garbage is outrageous, you don't know anything about corporate spying. Private eyes use all kinds of methods to dig up damaging information.
Veteran investigators, like former New York City detective Bo Dietl, say it's legal.
"The rules, you have to stand by, cause if you don't you're not gonna be in business very long," Dietl says.
In addition to dumpster diving to find documents, some commonly used tactics include:
According to court documents, the owners of Ringling Brothers infiltrated the animal rights group, PETA, after allegations that Ringling mistreated animals.
But there are limits. Anthony Pellicano — Hollywood's best known private eye — is now in prison, after accusations that he wiretapped celebrities.
"We don't go break and enter, we don't go and put a tap on phones, we do not that. There are companies out there that will do it, and they're committing felonies," says Dietl.
Treppel put a lid on his garbage with a subpoena. Now court proceedings may reveal if his rivals found any treasure buried in his trash.