Richmarr Construction Co., a Washington firm now in its 25th year, is building a development called Old Georgetown Village on a 76-acre tract north of Woodward High School in Bethesda.

The Nicholson Lane development's large, traditional town houses and rental garden apartments are nearly finished. Also planned are 180 units of garden condominium apartments. Later, in the 1980s the developers plan to add a high rise apartment building on the tract, formerly the estate of A. Lothrop Luttrell, a retired executive of the Woodward & Lothrop department store company.

The new development is to include tennis courts, pools and a community building.

Richmarr, which has built more than 2,000 moderately priced dwellings in Kings Park and Kings Park West in the Springfield area of Fairfax County, has owned the Nicholson Lane land since 1973.

Since sewer service was unavailable there, Richmarr joined a consortium of builders to build a new treatment plant to serve their developments. It opened earlier this year.

The Richmarr town houses went on the market several months ago and 70 contracts have been signed. Prices range from $120,000 to $139,000; the houses have 2,650 to 2,850 square feet of space. The first buyers moved in last month. Altogether, the firm plans to sell 198 town house.

Spring occupancy is anticipated for half of the 364 garden apartments, which are now being offered for rent.

"We are building rental apartments for future investment return rather than immediate cash flow as the result of increased costs of construction," said Richmarr partner Leonard Abel.

Apartment rents at Old Georgetown Village range from $410 for one bedroom with den to $540 for three bedrooms and two baths. Sizes range from 1,095 to 1,490 square feet.

Each unit will have independent air conditioning and heat pump electric systems. Tenants will pay their own utility bills.

Two-year leases are available.

Richmarr also recently completed the 220-unit Southampton town house development in the Pentagon City area of south Arlington. It was one of the area's hottest selling communities in 1977-78. Richmarr continues to build at Kings Park West and also at Lakepointe in the Burke area.

Most of the 10,000 units the company has built have been in Northern Virginia.