Concerns such as the home value decreasing, 24/7 humming noise, increase water bills, increase electric bills and other environmental concerns in regards to health. 

That is nuanced, but a few key elements are not taking the current financials, including rents at face value, another would be adding interior space without creating a bad floor plan, which is often converting a sunroom to a bedroom, finishing a walk-up attic, or finishing an unfinished basement.  

We just don't know the environmental impacts and ignorance is bliss.

He told me that he owned it free and clear, and that there were no environmental problems.  

Converting to a triplex = permits, zoning, and utilities.Before you fall in love with that plan, confirm the zoning actually allows for triplex or multi-unit conversions and that adding a 4-plex later won’t trigger new infrastructure or environmental requirements.

I am an investor in the Element Property in Sacramento.

Update;I had an "environmental" specialist come by and we noticed additional mold spots on the baseboards of an exterior wall that is shared by two different rooms (pictured).

ATUs are useful in environmentally sensitive areas or locations that are less suitable for conventional or gravity flow septic systems, such as inappropriate soil conditions where the water table is too high to allow the drain field to operate effectively.It seems likely your property has appreciated more than inflation and selling costs.  

Track the numbers and improve one element each week.

Also, there are a large element of risk using a volatile asset class likes stocks as collateral for debt.