"That trend has been going on for a while, and I think it's reflected in the policies that are in the Master Plan 2020, with the development of the areas that are designated as Community Enhancement Areas," Mayhew said.

Those areas, known as CEAs, are scattered pockets of the county that are considered "suitable for sustainable redevelopments that are compact, mixed-use, and walkable," according to the 2020 plan, which was adopted by the council Nov. 15.

"The ideal locations for CEAs are sites that exist within, or can extend traditional town centers," the plan states.

Whalen's inconspicuous 2-acre property on Kenwood Avenue is both part of a CEA — one otherwise comprised of land across the Beltway, including more of Whalen's land and the campus of Spring Grove Hospital Center — and within an area the plan designates as an "Urban Center Zone," where development is encouraged.

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In other words, the stretch of trees that Gratton never even considered developable has in fact been targeted by county planners as highly attractive for development.

PUDs at play

The trend has troubled many in Catonsville, said 1st District Councilman Tom Quirk.

"Baltimore County's in a transition, so to speak, because the way we do development has substantially changed in the last 20 to 30 years, and a lot of the high density land has been developed inside the URDL," said the first-term councilman.

"And if we have more density, we have to make sure it works with the community," he said. "That's a challenge that I think we're all wrestling with, trying to find the right balance."

Since 2005, PUDs have played an increasingly large role in the transition.

Between 2000 and 2005, there were 12 approved PUDs in the county, with an average size of 39.7 acres, according to data provided by Bruce Seeley, a Master Plan coordinator with the county's office of planning.

Since the start of 2006, there have been 21 approved PUDs with an average size of 20.2 acres. Of that total, seven were approved in 2009, six in 2010 and two so far in 2011.

If you exclude the two largest PUDs since 2006, which are disproportionately larger than the rest, the average size of the remaining 19 projects drops to 10.4 acres.

In Catonsville, three small-scale PUD proposals in particular have highlighted the community tension:

• Whalen's Kenwood Avenue project;

• a project to build an office building on 6 acres of the Catonsville Y's South Rolling Road property;

• a project to build 10 townhouses on just under 2 1/2 half acres of property off Thistle Road just outside Oella on Frederick Road in western Catonsville.

The latter, known as Thistle Landing, has been the most controversial for Quirk.

Approved by his predecessor on the council, Sam Moxley, the project was thrown off course when Quirk prompted the council to rescind its approval in May, calling it a bad project. Then in July, the council voted to reverse that decision, giving the project approval once again while also revising the PUD rules to require community and county agency feedback on PUD plans before they are brought before the council.

Quirk said he was "disappointed" by the council's change of course on Thistle Landing, but that the new rules for PUD review will help identify projects that will facilitate the county's evolving in-fill approach appropriately, while raising red flags on projects that won't.

"If it's done the right way, PUDs can be a very valuable tool. They might help with flexibility," he said. "But these are tough decisions, so analytically I'm trying to make sure I'm making the best decision with the most consideration for everybody."

Whalen said developers also have a responsibility to keep residents informed, especially with PUDs, and has held multiple voluntary community meetings on his project.

But developers can't do it alone, he said.

"There has been a disconnect between the planners and the planning reality and the community," Whalen said. "Everybody says, "Smart growth, yes! Green development, yes!,' until it's in their backyard, and then they say, 'Wait a minute. They're talking about density here.'"

Van Arsdale said she understands residents' concerns, but smart growth – which means working within infrastructure and avoiding sprawl – is "everything," she said.

"Change is difficult, but we want to make sure that the change is done for the best interest for the county as a whole and for the communities in which the development is occurring," she said.