Upper Limits on pH Disposal

Q. I am new at my position as health, safety and environmental manager for our manufacturing facility. Recently, I was reviewing our wastewater discharge and permit. Our only process wastewater comes from our three-stage washer, which consists of an alkaline cleaner, rinse and rust preventive stage. The rinse stage is a continuous flow when the washer is operating, while the other two stages are periodically dumped to sewer. The city periodically samples our wastewater at a manhole outside the plant, and all metal results for the last several years have been within limits. Because we only perform alkaline cleaning and rust prevention, our discharge is covered by local limits instead of metal finishing pretreatment standards. My concern centers around the alkaline cleaner stage. Current practice has been to dump this stage as is. Just before the last dump, I checked the pH and found it to be 12.7. I checked our wastewater discharge permit and the only pH limitation it has is that it prohibits pH less than 5.5. In other words, it has no upper pH limit. At my two other jobs, we were told discharging a wastewater of that high pH was “illegal according to EPA.” Since my discharge permit gives me no upper pH limit, am I OK? L. T.

A. L. T., whenever someone says “according to EPA,” they may really mean the city, county, state or USEPA. Be that as it may, there is a little known hazardous waste notification requirement in the USEPA general pretreatment regulations, 40CFR403.12 (p). Under this regulation, if an industrial user discharges a substance “which, if otherwise disposed of, would be a hazardous waste under 49CFR261,” a notification must be sent to “the POTW, the EPA Regional Waste Management Unit, and State hazardous waste authorities in writing...” The notification must include the name of the hazardous waste, the EPA hazardous waste number and the type of discharge (continuous, batch or other). If more than 100 kilograms (220 lbs or 26 gallons) in any calendar month are discharged, “the notification shall also contain the following information to the extent such information is known and readily available: an identification of the hazardous constituents contained in the wastes, an estimation of the mass and concentration of such constituents in the wastestream discharged during that calendar month, and an estimation of the mass of constituents in the wastestream expected to be discharged during the following twelve months.” This requirement does not apply for pollutants already reported under self-monitoring requirements if you discharge less than 15 kilograms (33 lbs or four gallons) per calendar month of a non-acute hazardous waste or do not discharge “any quantity of acute hazardous waste as specified in 40CFR261.30(d) and 261.33(e)”. Unless the wastestream changes, only a one-time notification is required; however, you must certify that you have “a program in place to reduce the volume and toxicity of hazardous wastes generated to the degree it has determined to be economically practical.”

The purpose of this notification is that your city or your state EPA will bring pressure to reduce or eliminate this discharge.
In your case, your spent alkaline wash solution has a pH of 12.7, which is higher than the corrosivity characteristic upper pH threshold of 12.5. Therefore, “if otherwise disposed of,” your spent alkaline wash solution would be a corrosive hazardous waste with hazardous waste code of D002. This assumes that the RCRA metals (arsenic, barium, cadmium, chromium, lead, mercury, selenium and silver) are not in high enough concentrations to fail the Toxicity Characteristic Leaching Procedure (TCLP). To put you in a position so you do not have to make this notification in the future, we recommend two actions:

1. Analyze your spent alkaline washer and rust prevention solutions for the TCLP metals to verify that they are below their respective TCLP threshold concentrations. If any of these metals are also regulated by local limits, ensure that these dumps do not cause non-compliance.

2. Before dumping the spent alkaline cleaner solution, add some acid to the tank in order to decrease pH to less than 12.5. This type of treatment does not need a hazardous waste treatment permit since it is related to a wastewater discharge under the Clean Water Act.

No notification is needed as long as these spent solutions are not RCRA-hazardous waste “if otherwise disposed of.”

As far as making notification regarding past discharges, I recommend you consult with an attorney specializing in environmental law so that you maximize your protection for this self-disclosure of a violation. As long as this discharge has not harmed the city’s sewer infrastructure or its wastewater treatment (aka reclamation) plant, there is a low risk that significant enforcement action would be taken.