Sunday night’s heavy rains were responsible for damaging a drainage structure in a park in Calumet City.

About 8 p.m. Sunday, a cover blew off a structure connected to the Deep Tunnel at Veterans Park after 1.8 inches of rain fell in one hour in the area, according to a statement from the Metropolitan Water Reclamation District of Greater Chicago.

The earth around the structure was displaced, creating a sinkhole around the structure, the statement said.

The Calumet Tunnel system — which holds 620 million gallons of water —was full as of 10 p.m. Sunday, the statement said. It’s part of the Deep Tunnel system, with a capacity of 2.3 billion gallons of water.

The MWRD secured the area and has begun repairs. No injuries were reported.