Evaluate for toxicity only those substances that meet the criteria for observed contamination in HRS 55 FR Page 51646, Section 5.0.1.
- The substance was found in a sample at observed release levels.
- The substance, if not at the surface, was covered by two feet or less of cover material (for example, soil).
Hazardous waste quantity is evaluated using Table 5-2, page 51647, rather than Table 2-5 which is used for the three migration pathways. Note that Table 5-2 is applied to areas of observed contamination, not to sources.
For tiers A and B (constituent quantity and wastestream quantity) count only those quantities in a liquid-filled area of contamination or that can be documented to be within the top 2 feet of other types of areas of observed contamination (contaminated soil, landfill, pile...).
- For areas of contamination other than liquid-filled impoundments and tanks/drums, this will usually force you all the way from tier A or B to tier D, area.
- For tier C, only liquid-filled impoundments and tanks/drums are considered. Otherwise go to tier D.
- For tier D, the divisors in Table 5-2 are larger than those in Table 2-5 because only the top 2 feet of the assumed depth of the source is considered.
- Because of the focus on areas of observed contamination rather than sources, the values for Hazardous Waste Quantity and for Waste Characteristics are frequently different than for the migration pathways, and if different, are almost always lower.
- For working your way through the tiers and for combining the values for toxicity and quantity, follow the procedure spelled out in Section 5 of this training course.
[Slide 4 of 6] [Home]