A group home for six mentally retarded adults will open in January at 900 S. Utah St. in Arlington, having won the Arlington County Board's approval for a building variance.

The home, the eighth established in the county by Arlington Community Residences Inc., ran into opposition Saturday from neighbors who expressed fears that the residents could be dangerous, particularly to children.

"We are most apprehensive, even fearful, of incidents that might happen," said Hoyt Lemons, who lives near the planned group home. "In general, bringing this type of activity degrades the community and . . . will bring down real estate values."

But Jill Gruever, ACRI director, said that at the other group homes in Arlington, in spite of considerable initial opposition, mentally retarded residents soon "blended" into the community. Gruever also noted that expressions of support for the program were voiced at a recent meeting of the Barcroft Civic Association.

Gruever defended the $875 monthly rent ACRI will pay for the four-bedroom house, noting that the site was chosen after an investigation of 20 other locations. Few landlords were willing to rent to groups and few would accept the three-year lease required by ACRI. According to Gruever, ACRI will renovate the building to meet state and federal standards.

Residents at the group home will spend their days in community programs and receive special counseling at the home itself. A counselor will stay overnight at the home to supervise the residents, she said.

Board chairman Stephen Detwiler cast the lone vote against the residence after noting that the house was "not adequately suited for the purpose." But board member John Milliken, who toured the property, concluded that the site was suitable and pointed to the "exceptional record" established by ACRI in Arlington.

Board member Ellen Bozman said other homes in other neighborhoods have disproved fears of declining property values. Lacking any evidence that the S. Utah Street home would be different than other such homes in Arlington, Bozman said she expected the mentally retarded tenants to be "as much a part of the community as any other householder."

In the absence of board members Walter Frankland and Dorothy Grotos, the motion for a variance carried 2 to 1.

According to Gruever, the home will be ready for its residents, both men and women, early next year, contingent on continued Medicaid funding for care for the residents. The residents will come from family homes and the Northern Virginia Training Center or as transfers from existing group homes.