Waste Profiling and Segregation

Proper disposal of regulated plant waste streams can be a confusing maze of processes and regulations. Staying compliant can become a high-stakes game that

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Proper disposal of regulated plant waste streams can be a confusing maze of processes and regulations. Staying compliant can become a high-stakes game that can leave a shop unintentionally facing stiff fines and unwanted attention. Understanding the basics of waste management can help shops avoid the pitfalls associated with waste handling.

Types of Waste

The first step in waste management is profiling or classifying the waste. In general, there are three types of waste, and those wastes are further broken down by either definition or characteristic:

Non-Regulated Waste – Typically no special handling or disposal requirements apply to this type of waste. Non-regulated waste is basically anything that can be put in a trash dumpster or recycling bin—paper, office waste, break room waste, general production area trash, etc.

Regulated Waste – Specific handling requirements apply. Regulated waste includes used oil, oily water, coolant, antifreeze, absorbent pads, floor dry, and used filters. Given record keeping practices apply; it is important to verify you are in compliance.

Regulated wastes may exhibit some of the properties of a hazardous waste but are exempted from the hazardous waste regulations to encourage voluntary compliance. Given that regulated wastes are special categories with relaxed management requirements, they include specific definitions. A good example of a regulated waste is used oil, in which the regulation specifically defines what is used oil (motor oil, transmission fluid, hydraulic oil, brake fluid, etc.) and what is not used oil (fuel oil and other fuels, crude oil, vegetable oil, solvents and oils used as solvents, etc.). It is important to note that water soluble coolants are classified as used oil by most regulators.

In general, mixing of different types of regulated wastes is strictly prohibited. For example, mixing used oil with any quantity of gasoline makes the entire volume a hazardous waste. Also, processing of regulated wastes can be viewed as creating a new waste stream that then must be evaluated against the more stringent hazardous waste standards.

hazardous waste

Hazardous Waste – When dealing with hazardous waste, exact labeling, storage, testing, as well as manifest, permit, and record keeping requirements apply, and verifying you are in compliance is a must. Formal self-audits should be performed. Large quantity generators typically are audited on an annual basis. Noncompliance will result in fines and unwanted publicity. There is no leeway here; it is either 100 percent correct or it is wrong in the eyes of the auditor.

Hazardous waste is defined by a material’s physical properties or if it is contained on special listings of chemical types and processes. This may sound simple, but it gets complicated. So much so, even a trained chemist can be challenged if he or she does not work with a given material type on a regular basis. In general, any material that leaves a shop that is not specifically exempted as a regulated waste must be evaluated against six hazardous waste characteristics and be compared against the lists of chemical types and processes. Four are of primary concern to metal working operations:

• Ignitable – Flashpoint of less than 140°F

• Corrosive – pH of less or equal to 2.0 or greater than or equal to 12.5

• Toxic – Any one of 40 specific chemical types at specific levels, with eight metals of particular concern

• F-Listed Wastes – Any one of 34 specific solvent types or mixtures used in degreasing and parts cleaning

We can see where things can ramp up quickly, and what a company thinks is simply used oil is actually much more. The line between regulated waste and hazardous waste is often a fine one, and comes with gray areas that make the entire process even more cryptic and complicated for those not trained in the process.

On Site Processing

Some shops attempt to reduce the volume and the associated disposal costs of their waste streams by processing it on site (i.e., waste evaporators, coolant splitters, and distillation units). Although the goal is to reduce the volume and the cost of disposal, a shop may conclude that, after totaling up the labor, facility, energy, residual waste stream, and capital expenses, it has actually increased its costs and exposure. Also, a waste that was once exempted from hazardous waste rules may no longer be exempted after processing—it is now a new waste stream to which the exemption and the relaxed management standards no longer apply.

Mixing Fluids

Mixing fluids can be a big mistake when it comes to industrial recycling. A good example is parts washer solvent. In an automotive shop, mixing parts washer solvent is acceptable under certain conditions (the key here is under certain circumstances); but, in a machine shop, the same solvent may be a hazardous waste because of what it is used to clean (for example, if it is used to clean steel parts containing trace levels of lead or chromium). Used oil is another common non-hazardous waste that, when mixed with any volume of another waste fluid (brake cleaner), can make the entire volume hazardous waste. Mixing also can result in unknown drums of material. These “mystery drums” can require expensive testing and often result in being categorized as a hazardous waste by default, because of the complexity and expense associated with proving it is not a hazardous waste. Taking the conservative approach of defaulting to hazardous also has the downfall of moving up in generator status from a small to large quantity generator. Remember, large quantity generators tend to get audited more often. Understanding what can and what cannot be mixed can save a shop thousands of dollars and perhaps its reputation.

Some best practices are:

• Never mix fluids unless you have been explicitly told you can

• Place materials into dedicated containers and label them using standard names

• Keep drain pans separate

• Always be conscious of what fluids are in close proximity to each other

Choosing the Best Path for Your Shop

As this brief overview shows, waste disposal can be complicated. When it comes to your shop’s waste, take your time in handling it and be deliberate in your decision making. When in doubt, contact an expert and make them explain what they are doing in Layman’s terms. If it does not make sense, take a step back and get a second opinion.


How does a shop end up in violation of waste disposal regulations? It’s not always as simple or intentional as one might think, as these brief (but real) examples would illustrate:

Machine Shop 1 – This shop mixed cleaning solvents with used oil—creating a hazardous waste. This can occur rather easily as a result of employees simply not knowing any better. The shop was inspected by the MPCA, which found the hazardous waste violation, resulting in a $150,000 fine. Even worse, the violation was published in the newspaper.

Machine Shop 2 – Violations don’t always come from the waste itself. Another machine shop did not follow proper labeling and storage requirements, which was the contractual responsibility of the subcontracted waste disposal company. This resulted in a $50,000 fine and the fine then was published in the newspaper.

This story originally appeared in the September/October 2015 issue of Precision Manufacturing, the Journal of the Minnesota Precision Manufacturing Association (MPMA).

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