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Procedures for Specific Hazardous Wastes

Individual Waste Streams: A waste stream generated from a laboratory procedure or shop process should not be combined with other chemical wastes.  The fewer the number of chemicals associated with a waste, the more economical is the disposal method for that waste.  If this is not practical, the Safety Office should be consulted about which wastes can be combined.

  • Non-Halogenated Flammable Solvents:  Non-halogenated flammable solvents are sent to an incinerator or recycler and must be free of heavy metals and reactive materials, e.g. sodium metal. Disposal of solvents to the sanitary sewer is limited to trace quantities of low-toxicity solvents, miscible in water, and diluted to non-flammable concentrations (<1% by volume).
  • Halogenated Solvents:  Halogenated solvents are disposed of separately and must not be combined with flammable non-halogenated solvents. Examples of halogenated solvents include methylene chloride, chloroform, and carbon tetrachloride.
  • Acids and Bases:  Small volumes of acids with a pH greater than six and bases with a pH less than 10 can be diluted and discharged to the sanitary sewer and followed by flushing with copious amounts of water. Acids and bases containing heavy metals must not be disposed to the sewer system.
  • Oils:  Oils are sent to a recycler. Only trace quantities of oils associated with cleaning and washing operations should be released to the sanitary sewer. Oil wastes from vacuum pumps, transformers, motors, etc., should be accumulated for pick-up. Oily rags should be sent to a cleaning service.
  • Biocides:  Concentrated solutions are not to be released to the sanitary sewer. Disposal is to be limited to one gallon of "working strength" solution per laboratory per day. This applies primarily to germicides and occasional disposal of pesticides. Chemicals which are persistent in the environment should be released only in trace quantities.
  • Sodium Azide: Solutions containing sodium azide, commonly used as a preservative in many in-vitro diagnostic products and with automatic blood cell counters, cannot be discharged to the sanitary sewer.  The accumulation of lead and/or copper azide in the drain pipes can produce a potentially explosive situation.
  • Toxic, Carcinogenic, Oxidizer, and Explosive Waste:  Are picked up for disposal.  Mark container as hazardous waste and transport to satellite accumulation area.
  • Compressed Gas Cylinders:  Disposal of non-returnable (i.e. lecture bottles) cylinders that are not empty can be very expensive, especially for reactive gases.  Make every effort to purchase form suppliers who have a cylinder return program.  Even if a cylinder seems empty, it cannot be discarded in the trash.  Always treat pressurized cylinders as waste and contact the Safety Office for disposal.
  • Unknowns: Unlabeled and unidentified chemicals present a challenging, dangerous, and very costly disposal problem.  Exercise every precaution to avoid generating unknowns in the laboratory and ensure that all containers are properly labeled.  If you discover unknown chemicals, please contact the Safety and Risk Management Office.

Needles and Syringes: Must never be put in the regular trash or the recycling bins. They must be accumulated in approved hard-walled containers. Needles and syringes contaminated with infectious agents must be autoclaved or otherwise decontaminated before disposal.

Broken Glassware/Sharps: Place uncontaminated glassware and non-regulated sharp objects in a plastic bag within a cardboard box identified with a label indicating “Non-Hazardous Glass and Sharps Waste”. 

  • Without compromising your own safety, clean all glassware of residual chemicals before disposal.  If chemicals cannot be removed, label the box with the chemical name and contact the Safety Office for disposal.
  • Use an approved labeled container. Dispose of uncontaminated glass in a glass disposal box.
  • Do not overfill the container.  Keep boxes to 30 lbs. or less.  When full, tie bag, tape lid closed, and place in the hall for housekeepers to remove. 

Infectious and Radioactive Waste: These guidelines do not apply to infectious or radioactive waste. Consult the Safety Officer for these types of waste.

Drain Disposal of Chemicals:

Only compounds that are water soluble to at least 3%, present a low toxicity hazard, and have a pH between 6 and 10 are suitable for drain disposal.  Limited quantities (generally not more than a few hundred grams or milliliters) of these chemicals can be disposed of in the sanitary sewer, but never in a storm sewer system. The disposal should be performed by flushing with at least 100-fold excess water at the sink so that the chemicals become highly diluted.  As a guideline, run the water at maximum flow for 2 minutes per 100mL of chemical.  Chemicals with an offensive odor are not appropriate for drain disposal and should be collected as hazardous waste.   During the disposal process, work slowly to avoid splashes and wear the proper protective equipment (lab coat, goggles, gloves).  Understand the hazards and toxicity of the materials by consulting safety data sheets (SDS) and verify that the material may be safely disposed of to the sanitary sewer.

Chemicals that are not appropriate for drain disposal are to be collected following the hazardous waste disposal guidelines.   The following discharges to the sanitary sewer are prohibited by the Clean Water Act:

  • Wastes that may create a fire or explosion hazard
  • Corrosive wastes with a pH less than 6.0 or greater than 10.0
  • Solid or viscous wastes in quantities that would obstruct the flow or interfere with operations
  • Heated waste that could either inhibit biological activities or increase wastewater treatment plant influent temperature to 104oF and higher
  • Waste discharges of any toxic waste material(s) in volumes or strengths to cause interference with wastewater treatment processes, or possibly contaminate waste sludge or effluent from the wastewater treatment plant so as to violate its NPDES permit.

Only neutral salts and buffer solutions may be disposed of down the sanitary drain.  Do not dispose of any of the following down the drain:

  • Acids with a pH less than 6.0
  • Bases with a pH greater than 10.0
  • Solvents
  • Alcohols, ethers, esters, ketones, aldehydes, amines, amides, nitriles, ethidium bromide, carbon disulfide, phenol or phenolic materials, halogenated or non-halogenated hydrocarbons, or other chemical agents unless present as trace constituents in aqueous solution
  • Sodium azide containing wastes
  • Formaldehyde containing wastes
  • Solutions with heavy metals

Contact the Safety and Risk Management Office for assistance with hazardous waste compliance (828-227-7443).

Hazardous Waste Containers

  • Containers and lids must be in good condition and chemically compatible with the waste inside the container.  Lab beakers, flasks, plastic household containers (i.e. milk cartons) are not acceptable as waste containers.  Metal containers are not acceptable unless they are the original container for the chemical waste being managed.
  • Containers must have securely fitting lids, preferably the original lid for the container.  Do not use corks, stoppers, a watch glass, or parafilm.
  • Waste containers must remain securely capped at all times (other than when waste is being added).  Evaporation of waste is not a legal means of disposal!  Do not leave the funnel in the container as this does NOT constitute a lid, even if covered with a watch glass!
  • Containers must be the proper size.  If you generate a large volume of liquid waste, consider a 5-gal pail for solvent accumulation.  Filled containers of liquid must have at least a 10% headspace to accommodate expansion during storage and transport.  Do not completely fill the container!
  • Allow chemicals to react completely and/or cool to ambient temperature before accumulating as waste; once the reaction has completed and the reagents cooled, pour into a compatible container and secure the lid.  In some cases, a vented container lid should be used.
  • Collect solid wastes in a double-bag lined cardboard box to prevent leaks.
  • Hydrofluoric acid presents a special hazard and must be stored in Teflon containers or the original product container. 

Labelling Waste Containers

  • The words “Hazardous Waste” must be on the label.  Always label waste to be collected with a red & white hazardous waste sticker.
  • Be specific.  Describe the contents of the waste container and include the following:
  • Chemical Name (in full, no formulas or abbreviations)
  • Any known hazards (flammable, etc.)
  • Concentration or other important information (pH, molarity, % by mass)
  • Solvent type, if applicable
  • Date of accumulation
  • Location where the waste is generated

Storing Waste containers

  • Store waste containers in secondary containment (trays, bins) to minimize the potential for breakage and subsequent leaks of hazardous materials.  If a spill occurs in secondary containment it should be cleaned up immediately.
  • Store incompatible waste separately (flammable & oxidizers, acids & bases, reactives, etc.)
  • Do not store more than 55 gallons in the accumulation area at any time.
  • Do not store more than 1L of acutely hazardous waste (P-Listed waste) at any time.
  • Do not store the waste in a location that could create a trip hazard, block the egress, or block access to emergency equipment.
  • The satellite accumulation storage area must be posted with a “Hazardous Materials Storage Area” sign.

Commonly Cited Violations

The most commonly cited violations of hazardous waste/material regulations include:

  • Open containers or lids not screwed on tightly
  • Improper labeling (missing information) or lack of a label
  • No secondary containment
  • Waste storage accumulation area (trip hazards, blocking emergency equipment, etc.)

What may seem like a relatively minor violation can result in fines of several thousands of dollars per violation.  Observing the waste guidelines detailed above and reviewing the following questions with lab personnel can keep the University in compliance:

LIDS – Are all containers closed with proper lids?
– Are containers stored in secondary containment?
– Are the containers properly labeled?
– Is the storage area in compliance?


Submit a Facilities Work Order request to initiate a waste disposal pickup from the Safety and Risk Management Office.  You will need to provide the following information:

Location of material(s)
A list of disposal materials and container size for each item
Contact information for the responsible party

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