of Number Four pump.
"Let's get in close." On instructions from the submerged engineers
both cranes lifted and hauled briefly. The tract slammed into the bulk
of the disabled pump. Troy and Alec played their lights over the
plate.

"This is the bottom plate," Alec said. "It's tipped all right. Got to
ease around to one side."

Again the cranes dragged and lifted and the massive tractor scraped
along the bottom plate of the overturned pump. Suddenly the vehicle
whipped forward. "Drop it," Troy yelled, and the carrier smashed to
the basin floor.

They were alongside the main outlet tube, now tilted downwards on an
angle towards the floor of the basin. Below them and under the
curvature of the tube was the pile housing. The explosive had to be
placed at the point where the pile housing, the pump base and the
outlet tub met.

Currents of water still swirled around them and tugged at the two men.
But it had much less force than during the downward descent. Alec
unclamped the seat belt, then slammed his magnetic clamp suit boots
against the outer plates of the carrier. His suit buoyancy dragged him
into an awkward crouching position and he swayed and fought against
both the upwards lift and the current swirl.

"Let's go," he said.

* * * * *

A hundred and seventeen feet above them, Hall and the crane operators
could hear the hollow clang of the magneboots as the two engineers
inched their way back alongside the tractor to a spot where the
tractor hull touched the pump housing. Alec cut one foot loose from
the vertical side of the tractor and slammed it against the pump base
and then quickly shifted the other foot and began forcing his way down
under the curve of the tube. Troy followed.

In the shelter of the base and tube, the current no longer pulled at
them and it was only the suit buoyancy to battle. It took them three
minutes to struggle their way to the juncture point. Alec wedged
himself in with his back against the housing above him and carefully
began unwinding the explosive belt he was wearing.

With his feet clamped on the vertical wall of the pump housing and
knees locked in a skier's stance, Troy handed over the first of the
magnetic clamps. Alec took it and carefully clamped the end of the
plastic explosive belt against the pile housing. They worked slowly
but steadily until the entire band of explosive was in place along a
five-foot arc of the housing.

During the