Prepare to get into the weeds... The EPA uses a system called HRS to score site for listing to the National Priority List (Superfund). The Hazard Ranking System (HRS) evaluates the relative risks to human health and the environment posed by uncontrolled hazardous waste sites. The HRS evaluates three things; 1) the likelihood that a site has released or has the potential to release contaminants into the environment, 2) the characteristics of the waste (toxicity and waste quantity), and 3) the people or sensitive environments affected by the release.
So for this site in particular you'd have to identify a release to the environment (the contamination that's undoubtedly present), it would have to be toxic (it likely would be), and you would have to have the contamination impact people. This is where the potential listing of the site would fall apart. Based on its location and land use, there won't be enough people impacted. In Tennessee, we get sites listed primarily by two exposure routes; impacted groundwater supplies (which are not used in Nashville) and impacted soil with residents nearby/on the property (which is not the case here).
I hope this explanation is clear enough. Obviously, its a complex federal program. For those interested, TDEC works closely with the EPA on sites where people are actually at risk from uncontrolled hazardous waste sites. FYI, there are no Superfund (NPL) sites in Nashville.