Extending public water and sewer lines to enable development of 325 new homes on a portion of Doughoregan Manor appeared to get a boost Monday during a three-hour, detailed County Council discussion of the complex project proposed for the historic Ellicott City estate.

Every county official questioned by council members on a range of issues brought up by critics of the plan said they feel the Carroll family's idea is the best way to proceed, though some issues -- like what to do with wastewater -- defied easy answers. The plan is to cluster the new homes in the northeast corner of the 892-acre estate, donate 34 acres to expand a county park and preserve the rest. Without that plan, county planning director Marsha McLaughlin said the risk is clear.

"I think over time, the property would be divided up in a slow and steady process," she said, as the family developed large homes on scattered lots to raise money as needed. But despite the seemingly consistent support, neighborhood residents who oppose the plan weren't impressed.

"The only people who testified up there are the people who are in favor of it," said Harry Carnes. "There's no resolution of the sewer issues."

Residents like Carnes testified over two nights of public hearings March 15 and 16 that the project would cause too much traffic, crowd area schools and could hurt their property values.

The council is scheduled to vote April 5 on the utility issue, which would amend the county's General Plan to move the western boundary for public utilities west to accommodate the plan. If it passes, council members sitting as the county zoning board must then consider changing the zoning on the 221 acres at issue off Frederick Road. In addition, a legally binding agreement between the famously private Carroll family and the county guaranteeing all the elements of the plan must then be approved for the project to go forward.

If the plan is denied, McLaughlin said the family would slowly build large new homes on big lots with wells and septic systems over much of the estate, risking its historic setting with suburban sprawl. The Carrolls say they need money to maintain and repair their nearly 300-year-old mansion house and 30 other nearby buildings, and to keep the property in family hands.

The estate is the last remnant of what was once a 10,000-acre colonial farm owned by Charles Carroll, a signer of the Declaration of Independence. It has been preserved in Carroll family hands for nearly 300 years, though other, contiguous portions owned by Carroll cousins are already in permanent preservation.

County planners, recreation leaders, the fire chief, and environmental, school and public works officials all said the family plan is a sound concept from each of those perspectives.

It would preserve as much of the estate as possible, while minimizing environmental impacts, expanding Kiwanis-Wallas Park and still allow the family the money they say they need. If the plan goes forward, the Carrolls would also get about $18.5 million over two decades for placing 500 acres of their land into the county's Agricultural Preservation program, which is funded by real estate transfer tax revenues.

County public works director James Irvin said the county's wastewater treatment plant at Savage will have enough capacity to handle sewage from Doughoregan and other nearby homes that would share the utility pipes, but that's not good enough given tightening state and federal regulations for protecting the Chesapeake Bay from nitrogen and pollution.

"We don't have a margin for error," he said. "It takes away from our cushion. We don't have a lot of excess capacity to play with," he said, despite a $100 million plant expansion now underway. Still, Irvin said the homes planned would produce far less waste than the 2,000 units once proposed on the same land as an Erickson Retirement Community.

Irvin wants the Carrolls to treat the wastewater on the estate and use it there or nearby to help preserve the Savage plant's capacity. No certain way to do that has yet been determined. If that proves difficult, the connection to public sewers would serve as a fail-safe, he said.

McLaughlin said the Carroll plan fits the county's General Plan guide by protecting high-quality, strategically located farmland, adding to parkland, protecting Frederick Road's scenic road status, and complementing the county's still-developing Historic Preservation Program.

"I think we need to preserve it now," she said.

School planner Joel Gallihue said new students from Doughoregan would be placed in schools to the west that have capacity, not Centennial Lane Elementary, and the county owns a site for a possible new middle school if one is needed. Room is available at Marriott's Ridge High School for older students, though no new homes will likely be ready until 2014.

Fire Chief William Goddard said recent council approval of a bill requiring residential sprinklers for all new homes eased his worries about fire protection. Ambulances would have no problem getting to the homes, he said.

"I am very comfortable with this project," he said.

Ned Tillman, the citizen chairman of the county's Sustainability Commission said clustering homes in one area is sound environmentally, and would not harm streams in the northeastern area of Doughoregan.

"It's an ideal place to preserve as much as possible," he said.

Former county councilman Christopher B. Merdon told council members that before leaving office in December 2006, county officials tried to find ways to preserve the entire estate without development, but no way to do that was found.

Joy Levy, administrator of the county's agricultural preservation program, said that about 1,430 acres of land around Doughoregan is already preserved, and if approved, the plan, plus several other parcels up for preservation, would help to nearly double that.

County parks director John Byrd said more playing fields would be welcome at Kiwanis-Wallas Park, and no officials said they had any thought of opening Burnside Drive, a dead-end street branching toward Doughoregan from Centennial Lane that residents want to remain closed.

Deputy county solicitor Paul Johnson said the council could help tie the plan together by adding requirements to the utility expansion bill that amends the county's General Plan. One thing no one needs worry about, McLaughlin said, is the Carrolls' devotion to preserving their home and property. They are doing "museum quality restoration" there now, as they can afford it, she said.

"I truly believe the Carrolls have a great deal of affection and sense of stewardship for this property," she said.