The ink on Philadelphia's zoning reform has barely dried, but Council nonetheless held an epic committee hearing Tuesday to debate changes to a code that took four years to write.

One of the proposals would return to the old standards under which businesses and other uses are permissible in neighborhood commercial districts - reversing an effort to conform the code to new-urbanism ideals of walkable, dense neighborhoods.

Another would change some of the requirements for notifying and seeking input from neighbors and community groups on proposed developments. That bill, sponsored by Councilwoman Jannie L. Blackwell, would affect the Registered Community Organizations (RCO) system established in the new code.

A starkly divided Rules Committee tabled two commercial corridor bills, sponsored by Councilman Brian J. O'Neill, until Dec. 13. The RCO bill passed unanimously after Blackwell and the Nutter administration brokered a deal.

Deputy Mayor Alan Greenberger noted that commercial corridors and RCOs "were probably two of most heavily debated, analyzed, and dissected issues we experienced in the four years of doing the zoning code."

He said the list of permissible uses for commercial corridors was discussed in "dozens and dozens of meetings," including some in O'Neill's office.

"This thing has been enormously vetted," Greenberger said. "Now what we have are amendments flying back and forth, some of which we haven't even seen, and I just have to tell you, we don't think this is the right way to do this."

The new code, which Council passed late last year, went into effect in August. The code included a one-year review to see what's working and what's not - a fact that opponents of the bills cited repeatedly in urging the committee not to act.

O'Neill introduced two bills - one that would revert to the old code for neighborhood commercial corridors, and one that would allow neighborhoods to adopt the new rules through a later process.

His bill would bar uses like pet stores, kennels, and group homes, as well as community gardens and farmers' markets, in those corridors. Businesses such as delis, dry cleaners, auto shops, and gas stations would need special permission.

O'Neill admitted that he had far fewer affected commercial areas in his Far Northeast district than other Council members do in theirs - the corridors are most prevalent in the districts that include Kensington and West and North Philadelphia.

He said he didn't have a problem with the new uses and more residential density in areas where development pressures are greatest.

"It's basically Center City and neighborhoods expanding and growing near Center City," he said. "The older, established neighborhoods - we called them areas of stability, not change - were pretty much OK under the old code."

O'Neill said the new code - and what it permits - could change the character of those "stable" areas.

His bills sparked an intense debate that drew Council members who don't sit on the Rules Committee into the chamber, including Maria Quiñones Sánchez.

"This impacts 60 percent of my commercial area," she said. "I'm very uncomfortable with this level of impact on my district without having enough time to study this."

Other Council members - Blackwell, Cindy Bass, and Marian B. Tasco - backed O'Neill because they opposed some of the new uses, particularly auto shops, allowed under the new code.

And several members wondered how they could be discussing zoning changes so soon after approving the new code.

"They spent four years working on this," Majority Leader Curtis Jones Jr. said. "Here we are back at square one."

But this was not the first councilmanic tinkering with the new code, and likely won't be the last.

Council members did not express similar consternation about changing the RCO system, and other alterations to the code remain in the legislative pipeline.

Blackwell even said she was eager to move the RCO bill because she wanted to focus on different zoning problems after the holidays.

"Next year, I want to go through the area of parking in my district," she said. "We got real issues."

Contact Troy Graham at 215-854-2730 or tgraham@phillynews.com, or follow on Twitter @troyjgraham.