How much should developers pay for the public facilities and government services necessitated by growth in Loudoun County?

That's a question that the county Board of Supervisors and other county officials are grappling with as they update their zoning ordinance and comprehensive plan to guide consideration of residential, commercial and industrial projects in Loudoun.

Not surprisingly, they are finding that easy answers are elusive.

The "conditional zoning" system, generally known as proffers, was granted to a few fast-growing localities in a series of General Assembly actions in the 1980s. It is still something of an experiment as the day-to-day mechanics of the system are worked out.

"It's all kind of an inexact science we're dealing with," said Supervisor Thomas Dodson (D-Mercer District) last week in a county board work session dealing with proffers.

Most developers need rezonings or special exceptions from the county government to begin their projects. Under the proffer system, the builder and the government negotiate over what amenities the developer should provide to help cushion the impact of the subdivision, shopping center or industrial park on the immediate area.

For example, a developer may propose, or the county may suggest, a package of improvements that the builder will perform or finance. The two sides may eventually agree that a road system in the new development, plus widening of a nearby highway and improvements to interchanges, should be paid for by the developer because the project will bring in additional traffic. Land for a school, park or library may be contributed as well. The final negotiations occasionally resemble a high-stakes poker game as county officials try to get every possible concession.

It's a voluntary system, but both sides acknowledge it's implicit that if the builder agrees to a certain amount of improvements, the Loudoun government likely will approve the development.

But what is that "certain amount" of improvements, and at what points during the construction process should the amenities be provided by the builder? Some efforts have been made in Loudoun and elsewhere to establish standards, but some county officials have indicated that different rules may be appropriate for different types of developments.

The proffer system "is the only way we have of sharing the cost of growth," said Supervisor Betsey Brown (D-Catoctin District) last week. "Our system, in my opinion, needs to be strengthened."

Brown suggested that the county government land planning staff hire someone to negotiate proffers with developers so that the county board no longer has the dual roles of final proffer negotiator and final decision-maker on the overall development proposal. Under the current system, she said, "after wringing some concessions {from the builder}, it's like a quid pro quo" that the project will be approved by the board, even if it has flaws unrelated to proffers.

Several supervisors said that the county planning staff is capable of handling negotiations and that the Board of Supervisors should be the final arbiter on proffers, zoning requests and related matters. But many agreed with Brown that there should be better guidelines and a well-defined process geared toward avoiding last-minute confrontations between the private and public sectors.

Now, "It's a terrible system" in some respects, board Vice Chairman Charles A. Bos (D-Leesburg District) said last week. He said some developers may hold back offering amenities, anticipating requests late in the process from the county.

Supervisor Steve Stockman (R-Broad Run District) said proffers "for the most part are market-driven," with the current downturn in the development industry limiting the volume of new construction and the amount of amenities that some builders can afford to provide. "Some may come back to you for downward negotiations," he said.

"It's a two-edged sword," said board member James Brownell (R-Blue Ridge District). "If you go too far, you may defeat the thing you're trying to do." Judges have in effect approved developers' rezoning requests when county government demands or restrictions were deemed excessive.

"The cost of other social services is never addressed" in the proffer process, said Supervisor Ann Kavanagh (D-Dulles District). She and some other officials have suggested asking developers to contribute funds to build or operate low-cost housing, libraries, facilities for the retarded and the like.

Bruce DeAtley, vice president of Intergate Investment Builders, said he favors including human services in the proffer process but noted that all developers have limits. "Do you have affordable housing proffers in lieu of other proffers, or does it get tacked on to other proffers?" he asked.

"It's a lot easier for a developer to go in with a rezoning application when he knows the parameters of what is expected," DeAtley said.