When you build a subway tunnel, you've got to move all the dirt that's underground out of the way. The usual way to do that is through a hole--known in the trade as a haul shaft.

Unfortunately for the construction firm hired by the Massachusetts Bay Transit Authority (MBTA)--which is attempting to dig such a hole at the corner of Mass. Ave and Garfield St.--building a haul shaft is a very dirty and noisy operation.

So dirty and noisy, in fact, that it prompted residents of nearby 1705 Mass. Ave--a Harvard-owned co-op building for 13 Dudley House students--to ask Charles P. Whitlock, master of Dudley House, to take steps to make their building habitable.

In turn, Whitlock wrote a letter to L. Edward Lashman, director of external projects and Harvard's man in charge of the Red Line extension, asking that the University take the necessary steps to stop the noise.

Lashman, who has already hired consultants to review the impact of the construction, said yesterday that before Harvard takes any action, the University wants to know the facts.

Original plans include a shaft--but not for hauling out the dirt. Somewhere along the way, however, somebody in the MBTA or the company changed his mind, Lashman said. in fact, one estimate said 90 per cent of the dirt would come out of the hole.

The tunnel is scheduled to go from Harvard Square to Porter Square. Needless to say, that's a lot of dirt.

MBTA spokesman John K. Leary Jr. said yesterday the MBTA plans to meet with its construction contractor to suggest revisions in their construction plans. Although an agreement will have to be hammered out, Leary said, the agency will suggest that only 30 to 40 per cent of the dirt come up next door to the Dudley Co-op.

Meanwhile, a spokesman for the contractor said yesterday they are "dealing with a very, very delicate situation."

And to complicate matters further, city manager James L. Sullivan says the city will cut off the company's water supply if it attempts to build temporary tunnel construction facilities.

"What can you do?" asked the company spokesman. At this time, nobody really seems to know.