Many of the conclusions and projections contained in recommendations for a new downtown D.C. plan released last week will require a good deal of fine-tuning to make the plan a reality.

In the meantime, a major question is whether the plan's major premise--that downtown will be the prime generator of jobs over the next two decades--is a realistic assessment.

Before the Mayor's Downtown Committee set out to produce the detailed plan for downtown, District planners cautioned that area "has a number of weaknesses which must be addressed before it can thrive."

High land prices, for example, "threaten the mix of uses necessary for an exciting and diverse downtown," and "office development could overrun the area," the office of planning and development noted.

In last week's report, however, the Downtown Committee, citing estimates from the planning office, said downtown "could reach a total of about 223,000 jobs by the year 2000, assuming land-use targets, a 73 percent increase from current levels."

More than 90 percent of that increase is projected to be in public and private office employment. Moreover, says the committee, most new office employment in downtown is expected to be in the private sector as the services industry continues to expand.

The Downtown Committee's report is weighted heavily in favor of service-type jobs, particularly at the entry level. But everybody doesn't aspire to being a waiter or a chambermaid or a clerk. And District residents will have to compete with their suburban neighbors, as always, for higher paying service jobs.

If downtown is projected as the prime generator of jobs, it should be in terms of balanced economic growth in the District.

District officials offer assurances that that will be the case. The downtown report was released as a separate piece of the overall comprehensive plan, they explained, because it is the most detailed. Further, said one, development was already booming downtown and "we needed to give that guidance."

What about other parts of the comprehensive plan that will address other areas as major employment centers?

James O. Gibson, the District's assistant city administrator for planning and development, believes firmly that downtown will continue to provide the bulk of jobs because the demand for office space along with government and tourism are the prime drivers of the local economy.

But the overall strategy, according to Gibson, is to plan for the development of other areas of the city that will generate jobs. That, he explained, means a strategy that includes development of secondary and intermediate office areas and light industrial sites.

"Nothing in our history tells us that we will ever be a preeminent industrial center," Gibson said.

On the other hand, he noted, "There is potential for industrial employment in the New York Avenue area," for example.

Lawrence Schumake, executive director of the D.C. Office of Business and Economic Development, agrees there is "tremendous potential" for redevelopment of the New York Avenue corridor as a major jobs sector.

Both men offered assurances that extensive planning has gone into considerations such as land assembly, leveraging of city-owned land for development, business retention and business attraction.

Although emphasis will be placed on wholesale and light industrial, that area has unlimited potential for high technology industry, Schumake noted.

He said the city has already surveyed the area to get a fix on businesses that remain and that a major effort is under way to increase business retention as well as business attraction.

But at this point, nobody seems to have a handle on how many jobs old and new businesses will generate in that area over the next two decades.

And while the planning continues, the District continues to lose jobs and businesses to the suburbs. The latest defection is, of all things, a major trade association that requires a considerable amount of office space.

The American Trucking Associations has decided to build a new headquarters in Alexandria after being in the District since 1940. The transfer of 300 employes from ATA's downtown location will cause considerable hardship, a spokeswoman said.

"We didn't want to move, but the District and the zoning commission kept dragging their heels so we got fed up and decided to move," the spokeswoman said.

The dispute, she explained, arose when District officials refused to allow ATA to expand its facilities by developing an addition on a parking lot next door.