5.1 Hazardous Waste Characterization & RCRA Subtitle C

Introduction to RCRA Subtitle C

The Resource Conservation and Recovery Act (RCRA), passed in 1976, establishes the framework for a national system of solid waste control. Subtitle C of RCRA creates a "cradle-to-grave" management system for hazardous waste, ensuring that it is safely managed from the moment it is generated to its final disposal. Environmental engineers must deeply understand RCRA Subtitle C regulations for proper waste identification, handling, and permitting.

Hazardous Waste Identification Process

Under RCRA, a material must first be classified as a "solid waste" before it can be considered a "hazardous waste." A solid waste can be a solid, liquid, semi-solid, or contained gaseous material. Once identified as a solid waste, it is evaluated to determine if it is hazardous. A waste is hazardous if it meets one of two main criteria: it exhibits a specific characteristic (Characteristic Wastes) or it is specifically listed by the EPA (Listed Wastes).

Characteristic Hazardous Wastes (D-Codes)

Characteristic wastes exhibit properties that make them dangerous or capable of having a harmful effect on human health or the environment. There are four characteristics:

1. Ignitability (D001): Wastes that can readily catch fire and sustain combustion. This includes liquids with a flash point less than 140°F (60°C), non-liquids capable of causing fire through specific conditions, ignitable compressed gases, and oxidizers.
2. Corrosivity (D002): Wastes that are highly acidic or alkaline. A liquid is corrosive if it has a pH less than or equal to 2.0, or greater than or equal to 12.5, or if it corrodes steel at a rate greater than 0.25 inches per year at 130°F (55°C).
3. Reactivity (D003): Wastes that are unstable under normal conditions. They can cause explosions, undergo violent reactions, generate toxic gases when mixed with water, or contain cyanide or sulfide compounds that release toxic gases when exposed to pH conditions between 2 and 12.5.
4. Toxicity (D004-D043): Wastes that are harmful or fatal when ingested or absorbed. Toxicity is determined using the Toxicity Characteristic Leaching Procedure (TCLP), which simulates leaching in a landfill. If the extract from this test contains concentrations of any of the 40 specified chemicals (e.g., Lead D008 at 5.0 mg/L, Benzene D018 at 0.5 mg/L) at or above regulatory levels, it is a hazardous waste.

Listed Hazardous Wastes

The EPA specifically lists hundreds of industrial waste streams as hazardous. These are divided into four lists:

• F-List (Non-specific source wastes): Wastes from common manufacturing and industrial processes, such as solvents used in cleaning or degreasing operations (e.g., F001-F005).
• K-List (Specific source wastes): Wastes from specific industries, such as petroleum refining or pesticide manufacturing (e.g., K048-K052 from petroleum refining).
• P-List (Acutely hazardous commercial chemical products): Unused, pure commercial chemical products that are considered acutely toxic even in small amounts (e.g., P042 Epinephrine).
• U-List (Toxic commercial chemical products): Unused commercial chemical products that are toxic but not acutely hazardous (e.g., U002 Acetone).

Special Rules for Hazardous Waste

To prevent loopholes, RCRA includes three critical rules governing mixtures and residues:

• Mixture Rule: A mixture of a listed hazardous waste and a non-hazardous solid waste is considered a listed hazardous waste, regardless of the concentration of the listed waste in the mixture. For characteristic wastes, the mixture is hazardous only if the resulting mixture still exhibits the characteristic.
• Derived-From Rule: Any solid waste generated from the treatment, storage, or disposal of a listed hazardous waste remains a listed hazardous waste. For example, ash from incinerating a listed waste is still hazardous.
• Contained-In Policy: Environmental media (soil, groundwater) or debris contaminated with a listed hazardous waste must be managed as a hazardous waste until the media no longer contains the listed waste (usually determined by risk-based concentration limits).

Generator Categories and Regulations

RCRA regulates generators of hazardous waste based on the amount of waste they produce in a calendar month. The generator category dictates the level of regulatory requirements, including accumulation time limits, storage standards, and reporting.

1. Very Small Quantity Generators (VSQGs): Generate less than 100 kg of hazardous waste, and less than 1 kg of acutely hazardous waste per month. They can accumulate up to 1,000 kg of hazardous waste on-site without a time limit, provided they comply with basic safety standards.
2. Small Quantity Generators (SQGs): Generate between 100 kg and 1,000 kg of hazardous waste per month. They can accumulate waste on-site for up to 180 days (or 270 days if the treatment facility is over 200 miles away) without a permit, provided the total accumulation does not exceed 6,000 kg.
3. Large Quantity Generators (LQGs): Generate 1,000 kg or more of hazardous waste, or more than 1 kg of acutely hazardous waste per month. They can accumulate waste on-site for only 90 days without a permit, and there is no limit on the amount they can accumulate during that time. They are subject to the most stringent requirements, including detailed contingency plans and biennial reporting.

Cradle-to-Grave Tracking

The EPA uses the Uniform Hazardous Waste Manifest (Form 8700-22) to track hazardous waste from the generator, to the transporter, and finally to the Treatment, Storage, and Disposal Facility (TSDF). Each party handling the waste must sign the manifest and keep a copy, creating an unbroken chain of custody. If a generator does not receive a signed copy back from the TSDF within 35-45 days, they must file an exception report with the EPA or state agency.