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9472.1994(01)

HOTLINE QUESTIONS AND ANSWERS

December 1994

2. Elementary Neutralization Units Generating and Storing
Non-Corrosive Hazardous Wastes

The operator of an electroplating facility neutralizes corrosive
D002 wastewaters with lime in an on-site tank. The neutralization
process causes a sludge to accumulate at the bottom of the tank.
Although it does not exhibit the characteristic of corrosivity,
this sludge from the treatment of electroplating wastewaters meets
the definition of FOO6 listed hazardous waste (40 CFR 261.31). The
neutralization process thus causes a non-corrosive hazardous waste
to be generated and stored in the treatment tank. Can this tank
meet the definition of an elementary neutralization unit?

This treatment tank at the electroplating facility meets the
definition of an elementary neutralization unit, because the waste
originally treated in the tank is hazardous only due to
corrosivity. According to 40 CFR 260.10, an elementary
neutralization unit is a device which: (1) is used for neutralizing
wastes that are hazardous only because they exhibit the corrosivity
characteristic, or are listed only because of corrosivity; and (2)
meets the definition of a tank, container, transport vehicle, or
vessel. As long as the original influent waste is hazardous only
due to corrositivity, generation of a new, non-corrosive listed or
characteristic hazardous waste during the neutralization process
does not automatically bar the tank from the elementary
neutralization unit definition. This tank is therefore eligible for
the exemption for elementary neutralization units found at 40 CFR
264. 1(g)(6), 265.1(c)(10), and 270.1(C)(2)(v). Units qualifying
for this exemption are not subject to permitting, generator on-site
time limits, weekly inspections, or other technical RCRA standards.
Since the elementary neutralization unit exemption applies only to
the tank and does not attach to wastes that are removed from the
unit, the F006 sludge formed during the neutralization process is
subject to full regulation as a hazardous waste once it is removed
from the tank for treatment and disposal.