Additional scope to test...what if there is no contamination found?

The way I read it, the site actually has to be a brownfield in order to achieve the credit. So I think they would lose both the credit and the money if it turns out not to be.

Also, remember that just because they 'always owned it' doesn't mean there isn't contamination. See: ....rolls downhill.and 'path of least resistance'.

I would say that if there is no reason to anticipate soil contamination, then the money would be better spent on something else. 

Rule #1: Buyer’s Remorse.   Rule #2: See Rule #1. Hire an Environmental Engineer, for both undeveloped and developed sites. I’ve been in the design/build/development/owner business for over 50 years, long before LEED. As early as the 1970s, specific property purchasers in the United States undertook studies resembling current Phase I ESAs, to assess risks of ownership of commercial properties which had a high degree of risk from prior toxic chemical use or disposal. Many times these studies were preparatory to understanding the nature of cleanup costs if the property was being considered for redevelopment or change of land use. Because a property has never been developed is no assurance that contaminates aren’t lying below the surface from nearby toxic sites. One example, abandoned gas stations with leaking underground storage tanks.   Rule #3: If no issues exist, consider the cost invested an insurance policy. No LEED credit is earned if the site and/or building has NOT been rehabilitated, i.e. restored to health.