In both cases, the regulatory threshold for lead is 5 mg/l; the only difference is the dilution factor used in the two test methods.

• Assume the lead is fully soluble in either extractant (acetic or citric acid).

• Determine the theoretical concentrations of lead to make the comparison to the regulatory threshold.

In both instances, the theoretical lead concentration exceeds the regulatory threshold. As a result, we have two options:

• The waste can be classified and managed as a toxic hazardous waste.

- or -

•  The waste can be tested by the WET and/or TCLP method(s) to determine the actual lead concentration in the waste.

If you already know the total concentrations of the regulated chemicals in the waste, you can use the dilution factor to determine whether to test the waste by the WET or TCLP method. To proceed with actual laboratory analysis, the minimum total lead concentration would need to be:

• WET: 50 mg/kg (5 mg/l x 10 = 50 mg/kg total lead)

• TCLP: 100 mg/kg (5 mg/l x 20 = 100 mg/kg lead)

The same rationale could be used with other regulated chemicals.

Caution: There have been some anecdotal instances where this strategy has not held true due to unique waste matrix properties.

Check out these case studies to see testing details, rationales, calculations, and conclusions:

            The 10x Factor: Solid and nonmillable/nonfilterable wastes

           Multiphasic Waste: When 10x doesn’t work

            Liquids: When soluble = Total concentrations

Activity 5b: TCLP vs. WET

E. Namel Painting Company

An inspector responds to an anonymous complaint that there are unsightly drums at a facility in the industrial district of town. The inspector found 10 drums in the back, some were rusty. There were 5 - 55 gallon drums - 3 contained dried up paint, but they had about 3 inches of dried paint residue on the bottom. The other two still had about 3 inches of liquid paint in them. The other 5 drums contain a sandy material.

The inspector talks to Mr. E. Namel of the business and finds out that they are closing the business and used to do a lot of sandblasting to prepare surfaces for painting. The owner specialized in using one type of paint product. The MSDS for the paint indicates that it contains 10% toluene (a "U220" and F003 listed federal chemical) and chromium.

Samples of the drums containing the sandy material was taken and found:

TCLP: 4 mg/L lead

Total Metal concentrations:450 mg/kg lead
500 mg/kg nickel

WET:20 mg/L lead
25 mg/L nickel