Elder Xiu led Qiao Ming and Yan Zhiqiu through a low, heavy archway in the southern outer edge wall of the writing hall. He dropped a narrow flight of timber steps that ended at the master drainage weir of Entry hall 636.
Here, in a cold, cavernous vault hewn from raw hard black rock, the excess water drops and sap-overflow of the Great Burl were gathered into four massive fluted water gates before being discharged into the upright depths of the deep gap.
The hard black rock weir was an ancient high-pressure marvel. The stone had been channeled with spiral dampening vanes that forced the rushing salt water into circular vortex pools, draining away its crushing striking force before allowing it to cascade into the drainage shafts. For ten thousand years, this weir had run clear, sweet, and pure.
The moment Qiao Ming stepped onto the wet stone ledge, his bare feet recoiled instinctively. The water running across the floor was not the sweet, stone-rich salt water of the upper terraces. It was cold, slick with a greasy film that felt gritty between his toes, leaving a dark, metal stain upon his skin.
The air in the drainage vault was heavy and choking, carrying a clear stench that Qiao Ming recognized with gut-deep dread: the acrid reek of sulfur coal, scorched grease, and molten iron.
