Almost a year old, the program has proven a huge success: The couple has distributed 80,000 poop-collection bags to 15 stations and disposed of 30,000 13-gallon bags full of poo (and other trash, because passersby use the cans as garbage cans, too). That's 390,000 gallons of dog dirt and other debris off the streets and sidewalks, thanks to them.
Such success has caught the eyes of community activists in a half-dozen other neighborhoods, who would like to adopt the program for their streets.
But there's one hitch. Program organizers attached Scoop the Poop signs, bags and deposit cans on city street signs. So for the program to continue - in Old City or anywhere - it has to get the city's OK.
Keisha McCarty-Skelton, spokeswoman for the city's streets department, said supervisors are evaluating it and expect to decide its fate sometime early next year.
For their part, users are big fans.
"I walk about 50 percent of the dogs in Old City, so I use the stations a lot," said Jaime Bennett, 32, whose dog-walking business Happy Tails of Philly has 300 clients.
Kalter and Schiavo first began pondering poop after a dinner party where guests complained about people who don't clean up after their dogs - or worse, those who bag droppings but then drop their putrid packages in window boxes or along curbs. Folks speculated that happened because you could walk for three blocks before finding a city Big Belly can.
"It's something a lot of people complain about, and neither of us are much for sitting back and listening to people complain," said Kalter. "We feel like something should be done instead of complaining."
She first came up with a poster, picturing neighborhood bulldog Buk in a military helmet as mascot, exhorting pet owners: "No pile left behind! Scoop the poop! That means YOU, soldier!"
Schiavo designed the stations, with plastic bags and cans to drop them into, soon after. Volunteers replenish the bags, bought with donations from community groups and businesses (including Bennett's), and empty the cans.
The city requires dog owners to pick up their pets' poo. Violators face $25 fines.
But it's a law that's tough to enforce.
"Unless you catch them in the act, it's hard to blame someone," McCarty-Skelton said, adding that streets-sweeps officers have issued 139 such tickets in the past three fiscal years.
Fury over feces spurred one man to allegedly kill another in February. Tyrirk Harris, 28, faces trial Jan. 28 on murder charges, after police said he shot neighbor Franklin Manuel Santana, 47, to death when Santana confronted him about the droppings his two dogs left around their Tacony block.
On Twitter: @DanaDiFilippo