Relief came to Kathy Costello yesterday in the form of a garbage truck.

It rolled down the hill into a drift at the bottom of her snow-covered cul de sac in Fairfax County and then, after collecting the neighborhood trash for the first time since the snowstorm, slowly labored its way out, cutting a path through the snow for Costello's car, which had been stranded since Friday.

"I ran right out and took advantage of the tracks," said Costello, whose house on Lavell Court in the Springfield area has yet to see a snowplow.

"I drove my car to the top of the hill and parked it there. I have to play bridge tomorrow, and that takes priority."

As area localities struggled to complete their snow removal efforts, Costello and her neighbors were among area residents still waiting--four days after the last snowflake had fallen--for a plow to dig them out.

Officials in most area jurisdictions said all streets had been plowed by yesterday, though officials in Fairfax and Prince George's counties and the city acknowledged that a small percentage of streets remained unplowed.

On Lavell Court yesterday, three-foot drifts alternated with deep ruts in the street, which runs down a gently sloping hillside from Carrleigh Parkway. At the top of the hill, a few cars and pedestrians floundered through Carrleigh's hubcap-deep slush in the direction of the nearest supermarket--more than two miles away.

"It seems like it's always this way," said June Romedy, whose husband called county officials seeking aid without success. "It seems like we're always the last."

Officials at the Virginia Department of Highways and Transportation, which is responsible for plowing the county's streets, estimated yesterday that 95 percent of the roads in Fairfax had been plowed at least once, and projected that practically all would be done by this afternoon. Hilly and dead end streets, they said, were taking longer than major thoroughfares.

"Hundreds of people have called us about their streets not being plowed," said Springfield supervisor Marie B. Travesky, who said the county was turning over all complaints to state highway officials.

That offered little comfort to the women of Lavell Court who clustered around June Romedy's kitchen table yesterday afternoon. Their hopes had been dashed on Sunday when a state snowplow came to the top of their street, started down--and got stuck. Neighbors dug it out with their shovels, but the plow's driver apparently thought better of the adventure and retreated.

"It kind of irks you when you do pay taxes," said Romedy. "You feel like they should take care of this instead of making you pay for it yourself."

Not that things were as bad as they could have been. In 1979, when a surprise winter storm caught all of their cars in the driveways, Lavell Court's hardy residents shoveled a path from the bottom of the street to the top--a distance of several hundred yards.

But because weather forecasters had broadcast advance warning of the storm last week, many of the residents of Lavell Court's two-story brick homes had parked their cars at the top of the hill before the snow hit and residents weren't trapped. So the snow gave Romedy a good excuse to wallpaper her bathroom, and prompted Caroline Johnston to invite over some neighbors for a marathon game of hearts.

Still, they'll be glad when it's over. "I'm ready to go back to work," said Rosemary Ihrig, a bus driver for the Fairfax school system. "I was even reading the National Enquirer. Now that's boredom."