Crawling the Siphon Throat

How many feet of silt had settled inside a thirty-six-inch overflow siphon that had not opened since the spring melt? Tidjani dragged his chest across the lip of the concrete culvert forty feet beneath the flooded boulevards, pulling his bulk forward by the rough aggregate of the pipe floor. His lumbar tank scraped the upper arch with a shrill shriek of aluminum on stone. The cold seeped through the thick vulcanized rubber of his dead drysuit, biting his ribs and calves with the full four-degree chill of mountain runoff. He had seventeen minutes of mixed gas remaining on his lumbar gauge, no hot water line, and no tender on the wire.

The siphon throat dipped downward at an eight-degree slope, curving beneath the seized housing of Turbine 4. Back in the primary intake, fifty tons of hydrostatic head hammered against the locked runner blades, creating a violent hydraulic vacuum. Crawling through the bypass siphon was the only route around that churn, but municipal maintenance manuals rated thirty-six-inch conduits for unequipped pipe crawlers, not heavy saturation divers in reinforced vulcanized rubber.

Tidjani stopped three body lengths inside the pipe. His exhaust bubbles tumbled along the concrete ceiling in frantic silver discs, breaking against hairline stress fractures. The space narrowed where black sediment and decomposed industrial tallow formed a hard bank along the floor. His broad shoulders wedged against the circular walls. If the first-stage regulator on his lumbar cylinder snagged an exposed rebar tip, the valve assembly could snap clean off the manifold, venting his reserve gas into the black water within three seconds.

He did not panic. Panic was a luxury for people with dry boots and surface lines.

Instead, he lifted his left arm, pressed the purge button on his wrist dump valve, and vented the pocket of trapped gas from his drysuit torso. The suit collapsed tight against his ribs, squeezing out three inches of displacement. He twisted sixty degrees onto his right flank, tucking his left shoulder down into the silt trough while keeping his right hand outstretched with the pneumatic cutter blade. The brass yoke of his lumbar cylinder grazed the concrete ceiling with a dull scrape, then slipped through the squeeze with two fingers of clearance.

The water in the siphon was dead and stagnant, thick with the stench of fermented sewage that permeated his exhaust valves. Then the current shifted.

A faint backwash pulsed against his faceplate from the lower conduit. It carried a sickening sweetness, like boiled pig fat mixed with copper shavings.

Tidjani froze, planting his gloved fingertips into the grit.

Two yards ahead, where the siphon leveled out into a horizontal run, something stirred in the silt bed. The beam of his helmet lamp caught pale, ribbon-like ripples drifting upward from the sediment. They were not weeds. They moved against the sluggish eddy, flexing segmented bodies the thickness of a man's forearm.

Spawn-leeches.

The large biomass wedged inside Turbine 4 was not merely anchoring its bulk against the impeller. It was shedding broods down the emergency conduits.

The first leech launched off the pipe floor with an explosive whip of its dorsal ridge. It hit Tidjani's helmet visor with a wet, heavy slap, spreading a circular mouth lined with concentric rings of amber cartilage teeth across the safety glass. Black digestive fluid squirted from its ventral pores, smearing the beam of his lamp into a greasy, blood-colored haze. The suction cup at its base contracted violently against his brass helmet collar, searching for the soft neoprene neck seal.

Tidjani braced his boots against the pipe floor. Squeezed in the narrow tube, he could not swing his arm or draw back for leverage. The creature's muscular body writhed against his visor, its cartilage teeth grinding against the heavy polycarbonate glass with a high-pitched squeal.

He reversed his grip on the pneumatic blade, bringing the flat of the heavy steel spine flush against the curve of his helmet shell. Sliding the edge under the creature's basal ring, he thumbed the air-pulse trigger.

The pneumatic cylinder fired with a sharp thud that resonated through his jawbone. A five-hundred-pound burst of pneumatic pressure drove the sharpened chisel tip straight through the leech's suction disc, pinning it to the lip of his brass breastplate. Dark, clotted gore spilled across his visor in thick ropes. The creature thrashed violently, its tail whipping against his mask until Tidjani twisted the blade ninety degrees, shearing the central nerve bundle against the metal rim.

The leech went limp, peeling away from his faceplate in the slow drift of the siphon eddy.

Before he could recover his balance, a second leech struck low. It fastened onto his left thigh, driving its feeding teeth into the reinforced Kevlar chafe-pad above his kneecap. The pressure was immediate and crushing, biting through layers of foam and canvas toward the flesh beneath. If the teeth punctured the inner drysuit seal, four-degree blackwater would flood the legs, destroying his buoyancy and dragging him to the bottom of the lower vault like an anvil.

Tidjani wedged his right boot against the pipe wall, locking his hips in place. He reached down his left leg, following the twitching, muscular flank of the creature with his gloved fingers until his thumb found the soft vent cleft behind its primary jaw. He rammed the chisel tip into the cleft, using his whole body weight to lever the blade upward.

The cartilage crunched beneath the pry-bar action. Black fluid erupted into the narrow culvert, clouding the water into an impenetrable brown soup. The leech's jaws spasmed and released, tumbling backward into the silt.

Tidjani lay on his chest in the dark, his breath roaring through the demand valve of his regulator.

He tapped his chest gauge with a knuckle. One hundred and thirty bar. Thirteen minutes. He had burned through four minutes of reserve gas in less than ninety seconds of close-quarters wrestling.

Under his left glove, something hard and angular shifted in the gravel bed beneath the dead leech.

His fingers probed the muck. It was not a rock or a fragment of collapsed culvert. He gripped a long, cold bar of cast bronze, thick with oxidized scale. He hauled it out of the silt.

It was a twenty-four-inch municipal spud wrench, heavy and drop-forged, bearing the stamped anchor seal of the Nouar-el-Bahr Drainage Works. Some maintenance tech had dropped it down the overflow hatch during the previous season's overhaul, leaving twenty pounds of marine bronze to sink into the bypass trap.

Tidjani tested the weight in his water-logged mitt. The jaw was solid, twenty pounds of dense metal that would not snap against rusted dogs or concrete jambs. He had no surface line and no pneumatic supply line to recharge his blade once the small charge canister ran dry, but this bronze wrench was a rigid lever and a brutal skull-cracker that required no air. He clipped the lanyard of the wrench securely to his central harness ring, right beside crushed Sensor 14.

He pushed forward again, using his elbows and knees to drag himself through the remaining thirty feet of the culvert. The pipe began to widen, its concrete walls opening into the vaulted brickwork of the lower collection siphon.

Ten feet from the exit grating, Tidjani stopped.

He switched off his helmet lamp, letting the subterranean black settle over his faceplate. Through the solid masonry of the culvert, the flooded vault ahead vibrated with faint, rhythmic shocks: the sharp click of magnetic boot soles against a steel catwalk, accompanied by the slow, metered flutter of composite combat fins.

He did not touch the exit hatch. He pulled himself flat into the silt bed, wedged his armored shoulder against the curved concrete, and laid the twenty-pound bronze wrench across his forearms. In the pitch black forty feet beneath the city, he slowed his breathing to a dead, even rhythm and waited.

"Come on down, then," he muttered into the dead air of his helmet. "Sump's open."