As a result, a standard may be either more or less stringent than one based solely on human health risks. Differences Between the States’ Groundwater Standards and the Federal MCLs

Because the federal MCLs are typically used as cleanup standards for groundwater used as drinking water at Superfund sites and many of the states based some of their own groundwater standards on the federal MCLs, we compared the states’ standards for contaminants to the corresponding MCLs. These standards tended to be more stringent than the MCLs. Overall, the states provided more flexibility in applying their soil standards than their groundwater standards. Flexibility to Adjust Cleanup Levels Based on Soil Standards to Account for Site-Specific Conditions

Eight of the 13 states that had soil standards indicated that they allow the extent of the cleanup deemed necessary under their standards to be adjusted for site-specific factors. Thus, cleanup levels can be tailored to local conditions. The degree of flexibility largely depended on whether the groundwater was considered a potential source of drinking water. The questions in our survey included (1) whether a state’s standards were derived from a risk-based formula and/or other factors, such as the naturally occurring levels of contamination in the soil and groundwater; (2) whether the formulas were based on EPA’s guidance or on the state’s own methodologies for estimating human health risks from contamination; (3) what risk levels, such as a 1-in-1-million increased probability of contracting cancer, were used in setting the standards; (4) whether the standards were set for different uses of the land or groundwater; and (5) whether the standards were considered fixed limits or the state provided flexibility to adjust the cleanup levels based on these standards to take into account specific conditions at a site. A recorded menu will provide information on how to obtain these lists.
Why GAO Did This Study

Pursuant to a congressional request, GAO provided information on how states establish and apply environmental standards when cleaning up Superfund sites, focusing on whether states: (1) base their standards on human health risks; and (2) provide flexibility so that the level of cleanup can be adjusted according to the extent of contamination.

What GAO Found

GAO found that: (1) 20 of the 21 states reviewed base their hazardous waste site standards on the danger posed to human health, and the cost and technical feasibility of achieving them; (2) states base their groundwater standards on existing federal drinking water standards; (3) when states set their environmental standards at levels other than the federal limit, they tend to be more stringent; (4) states provide more flexibility in adjusting the cleanup level when the cleanup involves soil pollution rather than groundwater pollution, in order to reflect a particular site's condition and health risk; (5) more than half of the states with soil standards regularly allow their cleanup levels to be adjusted for site-specific conditions; (6) less than one-fourth of the states with groundwater standards allow their cleanup levels to be adjusted; and (7) those states not allowing cleanup level adjustments view their groundwater as a potential source of drinking water and implement different standards, depending on the projected use of land or groundwater.