While much of the sophisticated, tradition-conscious development in Alexandria in the past decade has taken place in the city's Old Town section, nearly 200 acres north of Old Town's historic boundary have also begun to take on new vitality.

From Oronco Street, the area stretches northward to the Marina Towers apartments and the Pepco generating plant and eastward from North Washington Street to the river.

Engin Artemel, Alexandria director of planning, said that area includes 60 acres in industrial use, 23 in commerical, 22 in residential, 37 that are vacant, 37 used for streets and three acres of public parkland. He said it is likely that the Old Town flavor will be carried to the north in a combination of mixed uses of residential, commercial, industrial and office space. A waterfront park will be created on land traded by the developers of the Watergate at Landmark highrise complex for the nearby site where they are now building town houses.

Although the Marina Towers, Port Royal and Alexandria House apartment buildings are in the north water-front area, no new low-rise dwellings in the Old Town tradition were built thereabouts until Watergate of Alexandria opened last year.

One buyer, Roy (Pete) Kinsey said he recently relocated from an Old Town town house to the new Watergate cluster in the north waterfront area to avoid Alexandria's traffic in in his daily commute to Capitol Hill, where he is an administrative aide. He said the Watergate enclave of traditional dwellings has its own atmosphere - in a somewhat barren area of old commercial buildings and light industry.

Frances and Robert Peckmeyer moved to a two-bedroom Watergate town house because they wanted to be closer in. The Peckmeyers formerly lived in a house in Fairfax, but wanted "something new, smaller and well-located," Frances Peckmeyer said.

While most of the first section of Watergate of Alexandria town houses are sold out - at an average price of $125,000, according to sales agent Chris Burke - larger models now are being sold in the second section. She said new designs offer larger units that range up to $190,000 in price.

Since those Watergate dwellings were first offered more than a year ago, other changes have occurred in the north waterfront area, east of Washington Street and north of Oronoco.

Development Resources Inc., headed by Roger Machanic (who lives in Old Town with his family), has purchased the 240-unit Riverview apartment acomplex (just north of the Watergate site) for $3.1 million. Machanic said that this firm plans to raze the World War II-era rental apartments in easy stages to avoid wholesale dislocations of older tenants.

The firm will build town houses in clusters, with units priced from about $100,000 to $200,000. He said that 160 dwellings are planned over the next several years on the 7.1-acre site.

Just to the north of Riverview, the Olde Colony motor lodge also has expansion-development plans. Manager John Stevenson, who also overseas the nearby Ramada Inn-Old Town for Alexandria Management Corp. (headed by developer Gerald T. Halpin), said Olde Colony has razed the old Virginia theater on its site and plans to start a $3.2 million expansion program in December.

Designed by Walton, Madden & Cooper, the new section of Olde Colony will add 53 rooms for a total of 206, plus a restaurant, meeting and conference rooms. Stevenson said that the motor lodge at North Washington and 1st streets has been doing well and would benefit from more office space in the area. "We may build some ourselves in a few years," he added.

Randall Vosbeck, a partner in the VVKR architectural firm, which moved to a north waterfront location 12 years ago, commented that the newly developing area round the firm's building, at 720 N. Asaph St., deserves planning and traffic controls and good mixed uses. That firm designed the Watergate town houses.

Already under way on a site at Oronoco and North Lee streets, where Old Town ends and the north waterfront area begins, is a DRI project called Lee Street Square. Once the home of the Alexandria gas works, the site had been mostly storage warehouses until DRI won city approval to raze some structures and build a new office complex with two preserved Victorian brick warehouses as the keystone. Other low-rise office buildings are part of that development, scheduled to be completed next spring.