Rainwater drains from an acre uphill from us into an underground system that has been in place for 50 years. It works fine, except that the 16-inch round metal cover for the drain has rusted through. What is the name of this round piece, almost like a city sewer cover, but smaller and thinner? Without the right name, it's hard to find a replacement. Any suggestions on what it might be called?
Sump cover. Technically what you have is a Rainwater Collection Cistern, so Cistern cover, Cistern access cover or Cistern hatch cover all would apply.