The blast of the gate’s impact had not finished its work in the mountain.
Thirty feet above the floor of the sump, in the narrow water chute where Len had slid down from the quarry floor, the violent shock wave had shattered the century-old wooden props timbers supporting the overburden. A series of sharp, explosive cracks echoed down the tube as three twelve-inch oak baulks split longitudinally along their grain. They were followed by the ear-splitting roar of twenty tons of fractured limestone ballast collapsing into the channel.
A backup avalanche of gray boulders, gravel, and wet clay plunged down the chute. It slammed into the rear face of the dark rock drop-gate with the force of a battering ram. The rock choked the water chute fully, packing the access channel solid from floor to ceiling with an iron-hard plug of crushed stone.
The retreat route to the Quarry pit was gone. Len was sealed in the lower drainage chamber with sixty feet of solid rock above his head and five tons of dark rock barring the water chute.
Len looked up at the ceiling of the sump. His right hand instinctively reached up to check for falling rock. The limestone stone wall-brackets were weeping yellow water. But the heavy granite arches that supported the central overhead frame above were sound. Deren Vey had supervised the placement of those arches seven years ago during the lower gallery survey. He had insisted on double-pinned keystones anchored into the dark rock bedrock…
