The TTC recently conducted an evaluation of composite manhole lids and compared the results with a traditional cast iron lid. The lids were evaluated for both inflow leakage and live load testing using a 220-kip vertical actuator. Before placing the manhole ring and covers in the water tank for leak testing, a gasket was placed on the base of the tank to prevent water from migrating beneath the ring.The ring and cover were then place in the water tank and centered on top of the gasket.The composite system included an inflow dish that helps to minimize inflow leakage through the manhole lid. The lid was then tightened in place and the tank was filled with water to approximately 14 in. above the bottom of the gasket.
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