The Flap Valve

I lowered myself through the open grate into the circular mouth of the overflow conduit. The concrete bore was completely dry, sloping gently downward into cool gloom. Three paces in, a hinged cast-iron flap valve blocked the passage, wedged shut by accumulated silt along its lower pivot. I knelt and retrieved the straightened wire probe from my coat pocket. Working beneath the hinge pin, I picked away the hardened crust grain by grain until the iron cylinder ran free. Bracing my shoulder against the curved conduit wall, I exerted steady pressure against the flapper plate. The seam broke with a low metallic groan, swinging inward to reveal an unobstructed bore beyond.