The seven wooded acres on a hillside along the edge of the sprawling Colonial Village in Arlington are an oasis in the midst of the rapidly developing area, say residents of the apartment complex, and they want to keep it that way.

A plan to build four rental apartment buildings on the wooded area of the 55-acre complex will pit furious residents against the powerful landowner, the Mobil Oil Corp., today when the Arlington County Board considers the building proposal.

"Mobil made very clear promises that they . . . are disregarding," said Arthur Pearlstein, a Colonial Village resident and lawyer, who said that the firm has shown "reckless abandon without any concern for us."

Residents were told, he said, that any development on the parcel would be over the hilltop off North Rhodes Street near Lee Highway and out of their view, a major selling point to homeowners.

But Gregory J. Friess, executive vice president and general manager of Colonial Village Inc., says the residents are mistaken and were told on several occasions there could, indeed, be development there.

"Their charges are blatant and unfounded," Friess said. "We reject their charge of fraud. We have worked long and hard at building integrity."

Colonial Village Inc. is a wholly owned subsidiary of the Mobil Land Development Corp., the real estate arm of the oil firm. Calibre Co., a Northern Virginia devopment firm, plans to buy the land for a $20 million project that would include 384 rental units in four 6-story buildings, according the Calibre vice president William Ostrander.

The proposal to be considered by the County Board today represents far less density and height than the 468 units and eight-story buildings allowed there under county zoning laws, Ostrander said this week.

Current plans call for one of the buildings to be built on the hillside, which would have to undergo considerable grading, although the company is trying to preserve as many trees as possible, Ostrander said.

The rapidly developing urban area, sandwiched between the Rosslyn and Courthouse Metro stops, is dominated by high-rises, including three 14-story office buildings Mobil is putting up at the western end of the 50-year-old complex.

George Patton, vice president for marketing at Colonial Village Inc., said the land has always been marked for development on the county-approved long-range plan for phased redevelopment of the 951-unit complex, a mixture of rental, condominium and cooperative apartments.

"We're too close in to Washington to just sit here and grow trees on it. The taxes are too much," Patton said, adding that there would be a 260-foot buffer area of woods, including a ravine, between the new buildings and existing ones across North Rhodes Street.

The county's planning staff has recommended conditional approval of the project, chief planner Gary Kirkbride said. Changes the Calibre Co. has made show development would be "sensitive" to the ravine area.

The staff's main objection to the proposal, Kirkbride said, is Calibre's decision to put only 249 of the planned 441 parking spaces underground. Ostrander said putting more of the spaces underground would be financially prohibitive.