Hundreds of homes have been built in Germantown without the simultaneous construction of moderately priced units the developer promised, a lapse that is raising further questions about Montgomery County's planning for its fastest-growing communities.

County Council members, still angry over planning failures in Clarksburg Town Center, are demanding a thorough investigation, saying the integrity of the county's planning process and efforts to build affordable housing are at stake.

"How did this happen? If you know the policies and know the procedures, how did we let this happen?" council member Michael Knapp (D-Upcounty) asked.

Arcola Investment Associates has constructed 714 single-family homes in the Kings Crossing development. The 800-acre development is nearly finished, except for one five-acre parcel where 102 moderately priced dwelling units have yet to be built, said Steven A. Robins, an Arcola attorney.

Those units are forthcoming, the developer said, but have been held up by financing snags and a dispute with neighbors over whether they should be reserved for the elderly.

But several council members said yesterday it appears that the spirit of the county's moderately priced dwelling unit law has been violated, essentially segregating lower-income residents in one part of a community.

The law, often held up as a nationwide model, states that the affordable units should be built at the same time as the market-rate units. There also has been a long-standing policy against clustering the units, except if they are being built as senior housing.

The developer initially planned to build senior housing but changed the plans to townhouses that would be made available to anyone who qualified. Residents protested, so the developer is once again planning to build senior housing, Robins said.

Council member Steven A. Silverman (D-At Large), chairman of the committee that oversees land policies, said he plans to launch a review. "I want to get answers," he said.

Fueling council members' anger is the discovery this summer that hundreds of homes in Clarksburg Town Center, about seven miles northeast of Kings Crossing, were built in violation of height and setback requirements.

Clarksburg residents also allege that moderately priced units in that community are being clustered and built last. The county Planning Board is reviewing those claims.

The same planning department staff member who oversaw the construction of Kings Crossing was in charge of Clarksburg Town Center, documents show. The staffer resigned in June after it was discovered she improperly altered a site plan document to reflect what had been built at Clarksburg.

As in that case, the planning process for Kings Crossing appears to leave room for significant interpretation.

Robins said the site plan enforcement agreement includes a special provision allowing the moderately priced units to be built last because it would be senior housing.

But when the Planning Board approved the Kings Crossing project in 1996, the board said no building permit should be issued until a "final design" on the affordable units was completed.

"Presumably, building permits should not have been issued until the [affordable units] were created," Knapp said. "Somehow the building permits moved forward."

Council member Steven A. Silverman said he wants answers.