@Andy K  Here is a very good reference from the Environmental Protection Agency.  

If not, here is a link to the Landlord reporting form: http://www.maine.gov/dhhs/mecdc/environmental-health/rad/radon/documents/LANDLORDS%20REPORTING%20FORM%20FOR%20RENTAL%20TESTING.pdf which you will need to complete and return to DHHS Radon department.

Sometimes depletion of the reserves is a conscious decision and can be explained.  

Restrictions on what can be built,minerals rights,environmental hazards,flood prone,etc.

Mortgagor complaints: The mortgagor might find some defect in the property after taking possession, such as a leaky roof or rotten siding, an environmental violation such as heating oil residue, or a zoning or building code violation – and stop paying until you fix the problem.

An environmental engineering firm can conduct an audit for you and likely answer your question with certainty.

Example, a concrete yard for CA is 95/cubic yard, that's only concrete, plus you have environmental fees, pumper fee (if applicable), labor installation, another is, you can't hire someone below 15/hr here who knows what they're doing, unskilled labor, maybe 15/hr but all they do is carry materials, with work comp and taxes, if you pay at 15, you'll end up at 23-28/hr on carpenter trade.

I'm conscious of her preparing to move during the last month so that among other things is my hesitancy.

This is our first mobile home park purchase and we are doing due diligence following the workbook from boot camp.When we asked the seller for a copy of the survey and environmental study, the sellers agent said they did not do it when they purchased the park a few years ago and they also did not get it from the previous owner.Some agent said these two items are not required by bank so it is not necessary.

Please keep in mind that I have no experience in your market, I have no idea what local housing/rentals/environmental conditions are like.