A regional park proposed for Alexandria's Cameron Valley, beside the Beltway, should include a velodrome for bicycle racing, an indoor-outdoor swimming complex and two small soccer stadiums, according to recommendations a consulting firm has made to the Northern Virginia Regional Park Authority.

The consultants' recommendations were made this week at the last of three public hearings designed to help the Park Authority decide if a regional park should be built in Alexandria.

The Park Authority, which operates a dozen parks in Northern Virginia, already has earmarked $1.2 million to develop a major urban park. It tentatively approved Cameron Valley as the site for that park more than a year ago, but postponed a final decision until a consulting firm could provide a detailed study of the 77-acre site on the west end of Alexandria.

The consultants, VVKR and M. Paul Friedburg Partners, included no playing fields in an early draft proposal. Two soccer fields were added in their final recommendation because of community demand. Most of the 50,000 Washington-area youths who play soccer live in Northern Virginia, but the area has no good fields for the many soccer tournaments now being played here.

The consultants also recommended the velodrome and aquatic center become major features of the park, dropping earlier proposals for creating a transportation park, energy park, art park or urban wilderness area.

The velodrome would be comparable to one in Trexlertown, Pa., "which attracts 3,000 to 5,000 people on a Friday night" to see and take part in bicycle races, consultant Michael Cunningham told residents at the hearing this week. Washington is one of the East Coast's most active biking areas, with several bike racing clubs and the nation's single largest bicycle touring club, Potomac Pedalers.

An aquatic center would be built in stages, according to the consultants' recommendations, probably starting with a single outdoor pool and later adding the Olympic-sized, indoor-outdoor complex. The pool proposal, however, has been questioned by several Park Authority and Alexandria officials who have noted that a major swimming complex is being constructed by Fairfax County less than two miles from Cameron Valley, and that Alexandria is considering a city complex at Chinquapin Park.

In their final recommendations, the consultants called Cameron Valley "a controversial and technically challenging site" for a park. The site is bounded on the south by the Beltway, with its constant 70-decible noise level, and on the north by railroad and Metro subway tracks. The site is also split down one side by a 200-foot wide flood-control ditch for Cameron Run and a planned two-lane industrial road (Eisenhower Avenue). Fewer than 50 of the 77 acres at Cameron Valley actually are available for the park.

The consultants emphasized that their concepts can still be modified before the Park Authority makes a final decision this winter on whether to develop a park at Cameron Valley.

If the Park Authority approves the site, the question then would go to the Alexandria City Council which could hold more public hearings before leasing the land to the Park Authority. Alexandria invited the Park Authority to build a regional park at Cameron Valley.

At 60 of the 100 persons attending Monday's night's hearing were motorcyclists pressing for 10-to 35-acre motocross dirt racing track and an area for dirt bikes.

Park Authority Chairman Walter L. Mess said the authority tried two years ago to find a site in its 8,000 acres of parkland for motorcycle racing, but could find no place with suitable terrain or where residents wouldn't object to the noise. Several motorcyclists said Cameron Valley appeared to be perfect since the Beltway, railroad and subway tracks already make the area noisy.

Mess also read a letter from John F. Herrity, chairman of the Fairfax County Board of Supervisors, suggesting Cameron Valley as a site for a motorcycle track.

Timothy Elliott, chairman of Alexandria's park and recreation commission, objected. He said he did not believe a small urban park was the right place for a motorcycle track. Elliott suggested a more appropriate area might be on part of the sprawling Lorton prison complex in Fairfax County.