Woodward & Lothrop, the Washington area retail company that is one of the few surviving major independent department store businesses in the country, is about to embark on a five year, $20 million program of renovating its existing stores.

The decision to invest in modernization comes in the wake of the most successful year ever for the local retailer, president Edwin K. Hoffman revealed in an interview yesterday.

Sales volume in the year ended Jan. 31 totaled a record high of more than $241 million, up more than 10 per cent from the previous year, Hoffman said. Profits for the year also hit a new record, although Hoffman said specific figures were not yet available.

In the year ended Jan. 31, 1975, Woodies earned $9.8 million ($4.10 a share) and in the nine months ended last Oct. 30, the company's profits totaled $5.9 million ($2.46) on sales of $165 million.

Hoffman attributed the recent year's performance, which he called "sensational," to a strong recovery of consumer buying in the final days before christmas and during sales that followed the holiday. The annual sales gain was below the 16.5 per cent jump in the previous year, however, reflecting a generally weak consumer economy.

Woodies sales in December and January were about 10 per cent from the previous year despite a "very tough" first three weeks in December. Hoffman said his firm had "kept a tight lid" in expenses and inventories because of the sluggish performance and thus reaped significant profits when "sales increased like dynamite" at the end, at a time when overhead costs had been kept low.

"We are a very conservatively run operation . . . we never plan for a boom but we are ready to take advantage if it happens," he added.

For the future in metropolitan Washington, Hoffman indicated, his firm is counting on having many such opportunities. He revealed that Woodies:

By 1980, its 100th anniversary, will have transformed all stores so "they look brand new."Drawings and plans have started with demolition scheduled following next Christmas and renovations set to start mext January.

"Can't wait any longer" on modernizing its 27-year-old Chevy Chase branch at Western and Wisconsin Avenues. Although the company will continue to press forward with plans for a shopping complex on the site - blocked to date by Montgomery County lawsuits - a 15 million remodeling also will be drawn up, to be impremented early next year.

Will eliminate all remaining budget stores - not only downtown, as reported previously, but also at the Landmark, Iverson and Columbia shopping centers.

Plans a continued upgrading of its downtown store, including a relocation of men's wear to the first floor."We need space for a different merchandise mix," Hoffman said of the decision to end budget stores. "More and more of our business is becoming dominated by men's and women's apparel and accessories," which also means that some hard goods - particulary appliances - will be discontinued.

More than 50 per cent of the downtown store will be renovated, a decision Hoffman said is based on new business developed by the subway system and his expectation that a convention center will be built at Mt. Vernon Square.

Surveys conducted by Woodies show that 1,400 customers are traveling by subway and coming into the Woodies store between 10:30 a.m. and 3 p.m. each weekday, through a Metro entrance in the store's basement.New quick-service restaurant facilities have been added to serve these customers.

Hoffman said his company's biggest sons Corner Center in Northern Virginia, which he attributed to an expanded trading area created by the arrival last fall of Bloomingdale's.

The new competition from Bloomingdale's, including a secind store scheduled to open early next month of Rockville Pike; the affluent-oriented White Flint mall which will house Bloomingdale's; and the new Neiman Marcus at Western and Wisconsin Avenues have a "positive side>" Hoffman said.

"It makes guys in my business work a little bit harder to clean up, he asserted. Not that stores needed to be cleaned up, he hastened to add. It's just that you can't keep using the same fixtures for several years and look right."

Woodies also is planning to open new stores at malls in Gaitherburg, late in 1978, and in Northern Virginia in 1980 or 1981 - possibly in a Taubman Co. complex planned for the intersection of Interstate 66 and Route 50.

Beyong those large stores, Hoffman said, Woodies is drawing up a strategy that could lead to the opening of smaller units in a widerr trading area for greater regional retail market penetration.