Teeth in the Impeller

Why would forty tons of forged alloy seize without a single chipped tooth? That was what Tidjani needed to know before he crawled through the casing seam of Sump Turbine 4, forty feet below the storm-drowned pavements of Nouar-el-Bahr. If the bronze-nickel runner had shattered against a steel beam, jagged metal would slice his drysuit before he reached the hub. If it had not shattered, something softer—and far worse—had choked an engine designed to chew river driftwood into splinters.

He hooked his safety tether to the sixth guide bar of the trash rack. His left arm throbbed where the boneless sucker had bruised muscle through vulcanized rubber, but his fingers held the brass lanyard snap firm. At his hip, the specimen sack swayed in the cold current, heavy with three feet of rubbery, dead flesh.

"Telemetry has you at twelve meters, Old Brass-Lung," Zahara's voice crackled through the ear cups, clear above the drone of the topside diesel pumps. "Chief Mansouri just got to the truck. He's yelling into the dispatch radio. Central says the El-Mellah canal is six inches below the seawall lip. If Turbine 4 doesn't spin in twenty minutes, the lower tenements become a cesspool."

"Tell Mansouri to save his spit," Tidjani muttered into his oral-nasal mask. The copper tang of mixed helium-oxygen coated the back of his tongue. "Tell him the intake rack didn't catch scrap iron. It caught meat."

"He says you're seeing ghosts through dirty visor glass," Zahara replied. A metallic clatter bled through her mic—Mansouri banging his fist against the telemetry board. "He wants you past the trash rack and into the runner throat. The municipal dispatch log still insists it's a fatberg."

"Municipal dispatch sits three miles inland on limestone bluffs with dry socks," Tidjani said.

He checked the twin low-pressure hoses feeding his chest block, verified his hot-water suit bypass was flushing warmth down his thighs, and unslung his pneumatic chisel from the harness ring. The tool was eighteen pounds of cold zinc and stainless steel, fed by a reinforced air line clipped along his primary umbilical.

The clearance between the intake screen and the flared concrete intake throat measured barely four feet across. Tidjani turned sideways, exhaling in a slow, disciplined hiss to reduce his chest volume as he edged through the service gap beside the screen frame. The suction of the storm sewer pulled at his heavy boots, a heavy, blind drag toward the dark center of the siphon. Sixty thousand gallons a minute wanted to fall through this hole toward the sea, backed by a fifteen-foot hydraulic head from the flooded streets above. Only the jammed impeller held the deluge back.

Inside the cylindrical runner throat, the water lost whatever churn came from topside rainfall. Here, the flood was dead, heavy, and thick with settling silt.

Tidjani swept his helmet-mounted quartz halogen lamp across the curved steel plate. The beam cut twelve inches through suspended grease and sewage before scattering into yellow murk. He reached out with his left glove, tracing the cold contour of the guide vanes until his knuckles struck an abrupt barrier three paces past the casing flange.

It was not cast steel.

The surface yielded under his palm with the dense, cold resistance of cured rubber. Tidjani slid his fingers along the obstruction, mapping the geometry by touch. The turbine's four-blade propeller measured nine feet from tip to tip, each blade curved like a scythe to scoop stormwater into the outflow conduit. Now, the space between the blades was filled solid.

A wall of thick, fibrous muscle plugged the entire diameter of the pipe. It did not hang loose like river weed. It grew straight out of the steel hub, wrapping around the propeller root in braided cords as thick as a man's thigh. Where the leading edge of the third runner blade bit into the mass, the meat had not sheared; instead, pale cartilage rings had fused over the alloy, gripping the metal like scar tissue around an old bullet.

Tidjani pressed the flat of his palm against the center of the mass. Beneath three inches of slick, gray skin, a slow, heavy rhythm pulsed once every four seconds.

"Zahara," he said.

"Reading you, five by five. Did you find the hub?"

"I found the hub," Tidjani said. He kept his breathing low and shallow, counting the clicks of the exhaust regulator against his jaw. "The blades aren't broken. They're gagged. There's a plug of gristle five feet thick jammed between the shroud and the runner."

The comm channel hissed with static before a rougher, older voice cut in. Chief Mansouri had taken the headset. "Tidjani? Is it tallow? If the soap factories in Ward Seven dumped a vat of tallow, you can hit it with the steam lance from the tender truck."

"It has a pulse, Khelil," Tidjani said flatly.

Mansouri went silent. Topside, the faint, distant whine of emergency sirens leaked through the open microphone. "A pulse doesn't clear the intake, Tidjani. If you don't turn that runner, two hundred thousand people in the flats take the canal water through their parlor windows. Find the sensor well. Dispatch claims the telemetry fault is an electrical ground on Sensor Fourteen. Clear the sensor, let me reset the breaker from the board, and we'll jog the turbine motor."

"If you spin sixty tons of diesel torque against this thing without cutting it loose," Tidjani said, "you'll burn the motor windings and weld the drive shaft. Then you won't pump a thimble until summer."

He shifted his weight, wedging his heavy boots against the fixed guide vanes behind him. In the narrow throat, any sudden change in pressure would pin him flat against the runner face. Commercial divers died in siphons when differential pressure sealed them against an intake like a rubber stopper. Tidjani ran his gloved hand down the casing rim until his fingertips found the recessed collar of Municipal Sensor Fourteen.

The instrument was an eight-inch brass cylinder, threaded into the turbine housing to monitor flow velocity and water pressure. Now, the housing was bent forty degrees off-axis. The brass sleeve had been crushed inward, its armored cable ripped free and swallowed by the surrounding flesh.

Tidjani brought the pneumatic chisel up, setting the hardened carbide tip against the brass mounting flange. He thumbed the trigger.

The tool hammered out a rapid, deafening clatter that resonated straight through his helmet shell and into his skull teeth. Silt bloomed in gray clouds, obscuring the weak halo of his lamp. The chisel bit into the deformed brass, fracturing the corrosion seal around the threads. With each strike, the surrounding meat quivered, shuddering against the steel casing with deep, visceral tremors.

On the fifth hammer strike, the chisel punch pierced a hollow behind the sensor sleeve.

A jet of oily black fluid erupted into the floodwater, followed by a violent stream of yellow bubbles that hissed past Tidjani's faceplate. Through the micro-porous membrane of his drysuit neck seal, the water turned foul and scalding hot. The stench pierced the breathing mix immediately: rotten eggs, concentrated ammonia, and the sweet, suffocating reek of stagnant bile.

Necro-gas. The rotting pocket had fermented under four atmospheres of pressure.

Tidjani clamped his jaw shut, fighting the involuntary heave of his stomach. A diver who vomited into his oral-nasal mask forty feet under choked on his own bile before he could reach the surface. He wedged his shoulder against the runner blade, breathing strictly through his nose, letting the slow count of five steady his chest until the spasm passed.

With a final pneumatic burst, the chisel popped the brass sensor free.

Tidjani snatched the heavy cylinder before the siphon current could drag it down the runner gap. The brass was smeared with dark, gelatinous slime, and packed deep inside the sensor's intake port was a tangle of fine, translucent tendrils still clinging to the broken brass diaphragm. The stamped municipal serial number—NB-DP-04-14—was clearly visible across the flattened casing. Proof for dispatch. Proof that no fatberg had crushed this steel.

He shoved the sensor into his chest harness ring, clicking the carabiner shut.

"Sensor is clear," Tidjani panted into the mic. "The pocket is vented. But you aren't jogging any motor, Khelil. This thing isn't dead."

Before Mansouri could answer, a violent tremor ripped through the turbine casing.

The iron plates around Tidjani groaned under sudden, tremendous hydraulic displacement. Across the five-foot expanse of the meat wall, the smooth gray tissue rippled, pulling back in hundreds of concentric folds. From the center of every fold, pale, toothless leech mouths—each the width of a coin—opened in perfect synchrony, puckering into the churning blackwater. A high, vibrating hiss tore through the flooded pipe, vibrating straight into the soles of Tidjani's boots.