You're also probably going to want a geotech engineer to look at your soil to determine if any remediation will be needed to build a new foundation...Is 600 sq. ft. the footprint of the building or total sq. ft. that you can add.

They are now reviewing a lengthy phase 1 and 2 environmental report.

Look at what God is doing, congratulations on making a massive footprint in the industry!

Also you will want to make sure to check for or get a phase one environmental study if there has been equipment and fuels used or stored on the property.  

I also found out that the back taxes were inflated by about $1,750 due to an environmental assessment that had been added but never completed.

v=o9eXi3RL8q4&t=1sAfter watching this video, it dawned on my that China will never surpass the USA in becoming #1 economically, militarily, and environmentally.

JADU must be within the existing footprint of a primary home. 

There might also be some environmental issues due to the persistent leak.There might be other options like inserting a lining in the old pipe, which won't involve as much digging.

Some houses have the entire basement as a suite, so the footprint is the same as upstairs. 

Lots of potential environmental gotchas in that area.Also I would look into modular homes (If Springfield's Historic preservation society will approve).