The Alexandria City Council drew the line on crime yesterday, making it illegal to remove the chalk marks of the city's indefatigable meter maids from automobile tires. The new law was hailed by council members.

"It's unanimous," said Councilman Donald Casey, "and boy, do we need it."

In the city's Old Town section, where many side streets carry a three-hour limit on unmetered parking, spaces are at a premium. And the efforts of the city's notoriously efficient meter maids have given rise to a nervous syndrome that residents say is characterized by a furtive glance, a quick genuflection and frantic rubbing of the Firestones.

Call it wipe-and-walk, call it Operation Obliterate, but whatever one calls it, it was legal till yesterday.

"Oh, sure, everybody does it," said lawyer Kenneth Labowitz. "At noon around the federal courthouse it's incredible. All the clerks come out, wipe off the chalk, and move their cars up a foot or two. The meter maid goes by and everybody waves."

One Old Town resident claims to have seen two young men recently armed with sponges and a plastic bucket, making their way up a cobblestone street. The question Old Town residents ask is whether or not the two men were charging for their services.

"It's horrible," said Old Town resident Lenore Van Swearingen, of the parking problem. "We spend 30 minutes driving around to find a place to park, and you see people busy rubbing out chalk marks all the while."

Now, chalky fingers will cost a $10-to-$100 fine, according to City Attorney Cyril D. Calley.

There is a loophole. Technically, the law prohibits removal of the chalk marks while the car is in the space. There is nothing in the new ordinance to prevent scofflaws from pulling out of a space, removing the chalk and moving back in. In Old Town, of course, the space will probably be gone by then.