My house has been on the sewer main for 30+ years (original house built 1959, at least three owners ago), but a hole opened up about ten feet from my foundation. Looking down, it's a round cavity, 4 feet deep of air plus another foot of water. I was able to pull up a moon-crescent shape of a rusted metal (cover?) from the water. There are at least two narrow, old broken pipes which come into the hole from the sides. The walls of the hole are all dirt, I don't see any cement or metal walls. I tried to pound a 7 foot garden post through the water and mud but didn't hit anything hard except what seems to be mud.
Question: can I just fill it in with loose fill? Any concern 30+ years later of sewage material? Should I pump out the water first? Trying to save money and time, but do a good-enough job.
Thanks in advance