Stanford University

Handling & Storing Waste

Labelling Hazardous Waste Containers
  1. All containers of hazardous waste must be labeled properly as soon as the first drop of waste is put into a container. Do not wait until the container is full to apply a label.

    In order for EH&S to safely manage waste, your label must include the following:

    • The date the waste began accumulating.
    • Contact information for the generator of the waste (name and phone number).
    • Location of the waste (building and room).
    • List of all waste components, including the concentration of each (totaling 100%).
    • Hazard(s) of the waste (e.g. flammable, corrosive, reactive, toxic).

    Our convenient online system can assist you with creating a proper label and requesting pickup.

Determining the Hazard Category of Waste
  1. Selecting the appropriate hazard category can be difficult. EH&S has created a resource that lists the hazards associated with chemicals, known as the Chemical Safety Database, created to help identify and segregate hazardous chemicals that accumulate. It allows searches of chemicals by name, Stanford ID Number, and Chemical Abstract Service (CAS) Number. It lists the chemical’s physical properties, storage group and hazard category.

    Use the Chemical Safety Database along with the table below to determine your waste’s primary hazard category. The table matches the 40 hazard classes in the Chemical Safety Database with the five hazard categories found on hazardous waste labels. The lowest numbered classification equals the primary hazard.

    Hazard Category

    Database Classification Label Hazard category
    1, 8, 9, 10, 11, 18, 24, 25, 26 Ignore these non-chemical hazards
    7, 19, 20 Corrosive
    6, 16 Flammable
    5 Oxidizer
    4, 13 Air/water reactive
    Any other Toxic

Primary and Secondary Container Criteria
  1. When selecting primary and secondary containers for hazardous waste, follow the criteria in the table below. Almost any container with a proper closure can store hazardous chemical waste effectively, as long as these criteria are met. Remember to attach hazardous waste labels to primary containers only.

    Container Criteria:

    • Screw caps or tight lids are required.
    • Do not use parafilms or foil for seals.
    • Open only when adding waste.
    • The container must not leak when inverted.
    • Do not use beakers, coffee cans, or flasks.
    • The container should have no rust or leaks.
    • For solids, sealable plastic bags are OK.
    • Required for all wastes except immobile solids (e.g. gloves, large chunks of material, and gas cylinders).
    • For solids, boxes and containers with lids are OK.
    • For liquids, tubs, barrels, and trays are OK.
    • If holding a single primary container, the secondary container must hold 110% of the volume of the primary container.
    • If holding more than one container, the secondary container must hold 150% of the volume of the largest container or 110% of the combined volume of all containers (whichever is greater).


Secondary Containment
    • Put all hazardous chemical waste in secondary containers, except solids such as gloves, large chunks of solid material, and gas cylinders.
    • Secondary containers must be able to hold 110% of the volume of the primary container held within it. If more than one container is placed in a secondary container, then it must be able to hold 150% of the volume of the largest single container or 110% of the combined volume of every container (whichever is greater).
    • Wastes should be placed in a sensible location where they can remain under the control of one Principal Investigator (PI).
    • Wastes and non-wastes may be stored together.
    • Waste may be placed in a cabinet under a bench, on a shelf with earthquake protection, in flammables or corrosives cabinets, in a hood, on floor space, or in a refrigerator. Place waste as close to a generator as possible.
    • No more than 55 gallons of waste may be accumulated at a lab satellite accumulation area (LSAA) or satellite accumulation area (SAA) at any time.
    • No more than one quart of extremely or acutely hazardous waste may be stored at a LSAA or SAA.

Compatibility: Waste with Waste or with Container
  1. NEW – Chemical Incompatibility guide

    Wastes in primary containers should be segregated according to compatibility. A secondary container should only hold primary containers of compatible wastes. All waste accumulated in a common secondary container should be from the same storage group.

    Storage group information on most chemicals can also be found in the Chemical Safety Database. If lab space is limited, compatible waste can be placed with non-waste chemicals in the same secondary container.

    The following criteria will help you determine compatibility:

    Compatibility Criteria

    • Put acids and mixtures of acids and metals in separate primary and secondary containers.
    • Put primary containers in secondary containers, segregated by storage group.
    • Waste should be compatible with:
      • the original contents of a container
      • the container
      • other wastes in the container
      • wastes in all primary containers that are stored in a common secondary container
    • Don’t put hydrofluoric acid in glass.
    • Don’t put acids in metal.
    • Don’t put chemical waste in a red bio waste bag.

    • Segregate incompatible wastes from each other using separate storage provisions, such as secondary containers.
    • Do not mix incompatible wastes in a waste container.
    • Use the Stanford Chemical Safety Database and Storage Groups to determine if chemicals are compatible.

Storage Time Limits
  1. The storage time limit of a waste begins as soon a hazardous waste label is completed and placed on a container.

Satellite Accumulation Area (SAA) Requirements
    • No more than 55 gallons of any single waste may be accumulated.
    • No more than one quart of any single extremely or acutely hazardous waste may be accumulated.
    • Waste must be stored in the same room it was generated in, or in another room under the control of the same Principle Investigator (PI). All rooms where waste is accumulated must be close to each other and on the same floor.
    • Labs operating as satellite accumulation areas (SAAs) may accumulate or hold waste for up to nine months. It may take up to a month to have waste removed after submitting a pickup request, so you should submit your request before eight months have passed.

Waste Accumulation Area (WAA)
  1. Waste accumulation areas (WAAs) are areas that store waste, such as an outdoor holding area. Any amount of waste may be accumulated in a WAA. Storing waste in a WAA requires additional training. The following criteria must also be met:

    • The WAA must be properly posted, specially constructed, and in compliance with all requirements addressing the storage and disposal of wastes.
    • The WAA must be managed by specially trained personnel.
    • Weekly written inspections are required.
    • The accumulation time is limited to 90 days.

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