I purchased a piece of property that has a septic system on it. I found the tank but I'm not exactly sure what to make of it. First, it does appear to be a cast tank and not a old conder block tank. However, there's no lid on it, it's just a hole that someone put a piece of cinder block one and covered with dirt. There was an old house (circa 1960) on the property that was demolished before my ownership, so I'm not sue if maybe that contrator broke the lid or what happened. When I inspect the inside of the tank, the hole appears not to the solid waste side as I can clearly see a wall with a high opening to the right and the tank contines to that side. Looking at the tank there's an opening molded in to the side that is not in use and I'm not sure what it is used for. Here's an image: There's also a small box that appears to have a metal lid that I have no idea what it is for either. It has an NSF label on it: Does anyone know why there would just be a hole in the top and no lid? What would I do, just mold a new lid? Any idea as to the molded opening on the side and what that is for? What about the NSF box? Any help would be greatly appreciated.