The Arlington County Board voted yesterday to spend $10,000 to construct a five-foot high retaining wall to protect the Concord Mews condominiums against landslides from an 18-foot slope that adjoins the development.

The Board's decision ends a five-month dispute between the county and residents of the 74 town houses, each valued at $80,000 over who was responsible for repairing the damage that occurred in January when a large mound of earth slid down the slope owned by the county and onto S. Randolph Street, a private road.

The dirt has remained near the side of the road while both sides dickered over who would haul away the dirt and which party would be responsible should future landslides occur.

After several meetings between the residents and county manager W. Veron Ford and transportation director Henry S. Hulme, the county agreed to spend $2,000 to haul away the dirt and reshape the slope. However, Hulme and Ford said that future maintenance of the slope is up to the developer, Douglass Park Associates or its successor the Concord Mews Condominium Association.

"(The landslide) was created by the construction of a roadway across county land," Ford told Board. "(Legal) responsibility is cloudy from the beginning. We made several proposals in the nature of a compromise, but it's been all give on one side."

"We disgree with (that) assessment," said Kenneth J. Ingram, director of the Condominium Association. Ingram said he believed that the landslide was caused by a "supersaturation" of the slope caused by last winter's snowstorms.