In other words, if properly run, it could be profitable to provide the sewer utility for a park. 

If you don't know how to, you'll need to learn how to properly value properties or find someone, like a local investor or real estate agent, to help you.

How can I get the HOA to properly fix (dig up and replace) that part of the sewer line?    

You can always walk away, but I don’t think that’s the proper thing to do.

Jumping in without proper knowledge is not wise.

Are you looking for the proper fix or to cover the damage?

Consider the proper motivation should be focused on increasing cash flow. 

The broad consensus is the the '4% rule' is more of a rule-of-thumb than a proper retirement withdrawal strategy.

GC is a blue collar town and you don't typically hear about people moving there proactively, unless they're interested in the school district (they build a new HS right around the block from my duplex) and a lot of renters try and get in there during the mid-late summer to get their addresses in GC proper. 

Part of owning rentals(Correctly) is having proper reserves, so you should have the reserves to meet the higher deductible.