HIS SCRATCHED, bloodied arms covered with marble dust and sweat, Washington sculptor Leonard Cave began chipping away at a 16-ton block of white Georgia marble deposited in Founders Park on the Alexandria waterfront this week. The work-in-progress -- his largest ever -- is a highlight of the second annual Alexandria Sculpture Festival, which opened Sunday.

"I couldn't have afforded this on my own. That was the incentive for me," said Cave of his willingness to carve in public every Monday, Wednesday and Friday until the festival ends Oct. 29. By then he hopes the $10,000 stone, a gift from the Georgia Marble Co., will be fully transformed into a work of art. Anyone who doubts his ability to meet any sculptural challenge need walk only a few yards to inspect "Stronghold," his intensely dramatic piece in bolted wood that graces the landscape nearby.

Across the park, and closer to the Potomac, William Bennett is also still hard at work, laying arches of red brick -- also donated -- to complete a site-related structure titled "Waiting for Lost Ships." Designed as a symbolic boathouse-beacon of sorts, it looks more like an outdoor grill in its present incompleted state. But it promises much more.

So, it must be said, did the festival itself. And any shortcomings in imagination cannot be blamed upon the organizers. The city of Alexandria and a large festival committee invited all 73 artists juried into last year's festival to make proposals and, building on past experience, also offered to help find material and financial support for those who wanted it.

According to curator Gretta Bader, it was hoped that such a scheme would free artists to produce, without cost to themselves, site-related projects that would take full advantage of the city's glittering new waterfront park. A few artists -- notably Bennett, Joe Walters and William Walker Wood (who, unfortunately, was not permitted to float reflecting discs upon the river itself) -- took up the challenge with varying degrees of success. Most of the rest, however, ignored the challenge, and either by choice or out of sheer creative lethargy sent existing work that could have been shown anywhere.

Missed opportunities notwithstanding, there is enough good work to make a stroll through the park at the foot of Queen Street worthwhile, especially on a sunny day. Steve Bickley's flaming figure made from painted cutout steel and seemingly falling from the sky is affecting -- especially in the context of the ear-splitting crackle of aircraft going to and from National Airport. And Walters' attempt to evoke the archeological remains of an Indian village with half-buried 4-by-4s, though too orderly to be a ruin, gets points for trying to fulfil the proffered challenge of making a site-specific piece.

All together, there are 57 works by 34 artists, and they have been nicely placed not only at this site, but also around Market Square on King Street and in the lobby of VVKR architectural firm at 901 N. Pitt St. Two works stand out at Market Square: John Ferguson's graceful steel abstraction, "Whirligig," and Judy Miller's riotous "Club Rio," a tall, painted, wood column draped with a giant swagger of red cloth that amusingly thumbs its nose at the staid colonial-style City Hall behind it.

The show at VVKR is especially good this year, with a swooping ceiling installation by Hilda Thorpe and strong pieces by Joan Danziger, Mary Moll, Bill Bennett and Nicole Fall, who has created from clay a wittily surreal undersea still-life with flowers. Rockne Krebs, invited to join the show as a guest of honor, is represented by his "Green St. Palm," a steel cutout palm tree festooned with prisms that strew rainbows all over the walls and floors of the VVKR atrium whenever the sun comes out. How the owners of the building can part with that one is hard to imagine.

Taken together, the festival is an admirable and provocative enterprise that should continue -- and with luck, grow -- as time goes by.