The trading that went on at the Montgomery County Council last week over the purchase of the Potomac Horse Center took 10 minutes.

But a key part of the plan, which proved crucial to the decision to buy the $1.1 million center, probably will take considerably longer to implement.

In deciding to buy the center, the council specified that 48 moderately priced housing units be built on part of the 48-acre center. Because of the intricate details that must be considered -- zoning regulations, sewer lines, roads and other environmental concerns -- observers say it could be at least two years before the units are built.

The council also approved, over community objections, a similar plan to build moderately priced housing on the Bradley Junior High School site in Potomac.

In a community where environmental impact statements are the rule and where zoning regulations are scrutinized thoroughly, the council's decision left many county officials dumbfounded.

"You know what surprised is?" asked Royce Hanson, a leading supporter of the purchase. "Well, I'm simply amazed."

Hanson is chairman of the county planning board which will be charged with working out the details of the housing project.

The horse center is the Travilah area of Gaithersburg, where an average home sells for $300,000. Under the terms of the proposed sale, the stable owner, Frederick (Stretch) Harting, will rent and undetermined number of acres from the county for $32,500 a year and a percentage of his gross revenues.

Initially, Harting objected to the housing proposal. But when it became clear there would be no sale without that provision, Harting indicated he would be willing to consider the proposal.

"We tentatively agreed on things," Harting said after the council vote. "Then they threw the housing in, so now we're back in the renegotiating stage. I don't know how much of this land they want for housing -- if it's 40 acres or one or two. If it's too ridiculous, I don't need to sign. But I think it can be worked out."

Planning board chairman Hanson said details of where to build the homes and what type of housing should be built cannot be worked out until a contract is signed.

The housing proposal met with mixed reaction from residents near the horse center.

"I think it's for the birds," said Frankie Murphy, who lives 1 1/2 miles from the center. "We don't need this dumped right in the middle of us. What will it do to the resale value (of our homes)? I didn't move out here to have this happen.

"I think it's absolutely sinful for the county to even think of such a thing."

However, Rilla Ledge, who lives about 3 miles from the center and who operates a nearby Montessori school, disagreed.

"I don't object to a moderate income development any more than I would object to a $250,000 development."