255. A covered facility collects run-off from ore piles, natural topography, waste rock piles, and other on-site features in an on-site pit. The facility precipitates metals from the collected water by adding hydroxides to the pit. Is the resulting sludge, and any discharges from the pit, exempt from release and other waste management reporting under the intake water exemption?
The intake water exemption is specifically limited to otherwise use of toxic chemicals present 'in process water and non-contact cooling water as drawn from the environment or from municipal sources'. (40 CFR Section 372.38(c)(5)) In the scenario described above, the facility is actively using hydroxides to precipitate out metals. The facility is using storm water run-off as part of its process sequence to extract desirable materials. Amounts of listed toxic chemicals contained in storm water run-off are exempt from otherwise use threshold calculations, but any new listed toxic chemicals which are manufactured from the facility's use of the storm water must be counted toward the facility's manufacturing threshold. Likewise, any toxic chemicals that are recovered and distributed in commerce must be considered toward the facility's processing threshold. The facility would also have to account for amounts of listed chemicals acquired by the storm water after the storm water has run onto and off of equipment and buildings.