IT WAS bypass surgery over the Van Wyck.
 

  Workers last week fixed a leaking water main at 101st Avenue by cramming a flexible plastic pipe into the damaged artery and blowing it full of steam to ensure a water tight fit.
 

  Officials from Jamaica Water Supply, which owns the drippy line and two others like it, said the new procedure saved commuters weeks of grief and the water company a lot of money.

  The three mains, which hang beneath the Van Wyck Expressway overpasses at Hillside, 101st and 109th Avenues in Jamaica, have been leaking for more than a year, creating icy conditions on the highway and forcing the water company to shut them off during the winter.

  Replacing the 12-inch, cast-iron pipes would have taken at least a month each to complete, project manager Bob Swarth said, and "we'd probably have to shut down part of the Van Wyck."

  Instead, a new polyethylene tubing was pulled into the 40-year-old pipe and blown full of steam until it expanded to fit and seal the main's interior. The whole procedure takes about three days to complete, Swartz said.

  The process bore a strange resemblance to heart surgery. First, workers opened the main at either end of the overpass and scoped the interior with a video camera. Then, four decades worth of scale and mineral deposits were flushed out. After that, 150 feet of folded polyethylene piping was greased up and pulled through with a winch.

  There was an air of jokey expectation as workers at the east end of the 101st Avenue overpass slowly unrolled the liner from an 8-foot spool and fed it into the main.

  "It's a boy!" cried winch operator George Henriksen, 33, as the white tubing appeared at the other end.

  Next came capping the plastic sleeve and pumping it full of steam for three hours. "We're waiting for the heat to permeate the tubing, so when you're done you get a nice tight fit," said Tom Checchia, director of operations at New Hope Pipe Liners, a Wharton, NJ, contractor, as a small geyser billowed out over the Van Wyck.

  In addition to sparing the denizens of southeast Queens yet another abominable tie-up, repairs at the three overpasses will save quite a bundle. Work at 101st Avenue cost Jamaica Water Supply around $370 a foot, according to Swartz, or $55,500 total. To replace the main from underneath would have cost $150,000.

  The procedure will allow 1 million to 2 million gallons of water to flow daily through each of the three mains, bringing improved water service to communities west of the Van Wyck such as Richmond Hill-just in time for the summer months, Swartz said, "when there's a high volume of water usage."

Newsday Photos / Jonathan Fine