Volume 6, Number 2, May 1984, pp.8-13

Hazardous Waste Disposal

by Caroline Black and Chris Stavroudis

("Hazardous Waste Disposal" is based on an interview with Dr.R. Nichols Hazelwood. Before the interview he was given a list of 65 chemicals most commonly used by conservators.

Dr. Hazelwood is the Environmental Affairs Project Manager for IT Corporation. This California based corporation is a full line hazardous waste management company which operates and designs treatment facilities, disposal sites and analytical laboratories at various locations around the United States. IT Corp. operates a fleet of 150 vacuum trucks and also works with companies to help them decide how to handle their waste. It performs site investigations, responds to emergency calls about spills and does heavy industrial cleaning. Founded in 1926, IT Corporation went public in December 1983 and is rapidly expanding nationwide.)

Although conservators are well aware of the dangers involved in working with chemicals on a daily basis and articles have been written suggesting methods for proper storage, most conservators don't know how to go about safely disposing of these chemicals after having used them. Some of these materials are highly toxic and many are incompatible when mixed together. This article should help conservators address the problem of waste disposal. Most recommendations are made to maintain compliance with legislation and regulations in California, which are among the most stringent requirements in the country. After some initial research, the authors' impression is that most states are just trying to identify and cope with the vast problems inherent to the disposal of waste materials. Mechanisms for disposal, particularly of the small quantities produced by conservators, are for the most part only beginning to be put into place. However, the agencies we contacted were most willing to give advice and direction.

The Problem With Chemical Waste

The moment you open and use a can of solvent you are a waste generator. Conservation laboratories may only produce 10 to 15 gallons of waste each year and private conservators only one quart, still the improper disposal of even small quantities may cause unforeseen problems. Chemicals dumped in the back yard will filter down to the water table. It might take years, but they will eventually pollute that water below. Some chemicals washed down the drain produce flammable vapors which can collect in stand pipes and explode.

The bottom line is that California does not exempt small generators and if you do not dispose of waste properly, you are actually breaking the law and may be liable to stiff fines for non-compliance.

Current Legislation

Under federal regulations anyone generating less than 1,000 kilograms of waste chemicals per month is considered a small generator and may dispose of waste in common garbage which is taken to a municipal land fill or a waste facility. It is more likely, however, that the laws in your state are more restrictive. To find out, call the local health department, sewage disposal system, or a waste management company. Kansas, Missouri, New Hampshire, New Jersey, South Carolina and Vermont currently exempt only 100 kilograms per month. Minnesota has proposed rules to exempt 100 kilograms per month. California, Rhode Island and Louisiana are unusual because they have no small generator exemption and any quantity of waste must be handled according to the hazardous waste system.

Disposal Methods in the Conservation Studio

In-house disposal methods should be viewed with caution. Of the following alternatives, only a few are acceptable.

The materials used by most conservators can be broadly grouped into chemical classes. These classifications are: solvents (including paints and varnishes), detergents, acids and alkalies, bleaches and ethyl ether. As a general rule these classes should not be mixed together in a waste container. The possibility of chemical reaction between incompatible materials is a genuine fire and safety hazard. (See Chemical Incompatibility.)


Solvents, as a class, present a known fire and health hazard and accordingly also present disposal and storage problems. Included in this category are: paint, varnish and polymer residues, as well as true solvents like toluene and naptha. (Diethyl ether is categorized with ether.) Solvent waste should be collected in glass bottles for future removal from the lab. Glass is inert and unlike metal, will not rust through if water is mixed in with the waste. (See Collecting and Cataloguing Waste for Removal.)

Small amounts of waste solvent may be allowed to evaporate in a fume hood or equivalent.

It must be emphasized that dumping even water soluble solvents down the drain is not an acceptable practice. Flammable vapors can collect in traps and stand pipes creating a fire hazard.


Only detergents can be safely and legally disposed of down the drain without prior treatment. With the exception of triethanolamine, sewage plants are designed to accommodate this waste. Triethanolamine should be disposed of as the waste solvents are. Do not collect this material in a metal can if it has been mixed with water.

Acids and Alkalies

Acids and Alkalies may be disposed of in the sewer system under certain conditions. If the acid or base does not contain dissolved heavy metals, it may be neutralized and then washed down the drain with plenty of water. If neutralization is possible, protective gear such as rubber gloves, an apron and a full face shield should be worn during the process. Acids can be neutralized with sodium bicarbonate (baking soda) or sodium carbonate (soda ash). Alkali can be neutralized with acetic acid (vinegar), or even better, photographic indicating stop bath (add stop until the red color is produced.) While not recommended, if other chemicals are used for neutralization reaction, an indicator like methyl red should be used.

Please note that waste containing dissolved heavy metals should not be disposed of in the sewer system under any conditions. Metals such as copper, zinc, lead, cadmium and mercury are toxic and can kill the bacteria which is introduced at the treatment plant to work on the sewage. This reaction requires the plant to initiate a new treatment cycle.

If neutralization is not possible, the waste must be containerized for removal. (See Collecting and Cataloguing Waste for Removal)


The very mild and dilute bleaches used in conservation treatments should be neutralized before disposal in the sewer system. Many of the bleaches self-neutralize with time. Sodium perborate, hydrogen peroxide, sodium borohydride and chlorine dioxide generating baths, each in dilute aqueous solution, should stand for an hour in order to avoid complications in the sewer system and then be discarded. Chloramine T may be diluted and washed down the drain, as it is often used in water treatment plants. Other bleaches must be neutralized before disposal.


Ether, diethyl ether and ethyl ether all refer to the same material. Petroleum ether (pet ether) is not the same chemical and is handled like the solvents. Ether is terribly dangerous because it is highly flammable and a terrific explosion hazard. Its vapor is heavier than air and creeps along the floor. If it finds an open flame, the fire can flash back to the container. No one should ever smoke or have an open flame near an open can of ether.

Ether reacts with air to form shock sensitive explosive peroxides. For this reason it should always be kept in a metal container which will inhibit the formation of peroxides. Ether must never be stored in glass jars. Bottles of ether contaminated with peroxides have been known to explode from unscrewing the lid. Be aware that although metal inhibits the formation of peroxides, it does not remove existing peroxides and new peroxides still may form.

As a general rule, ether stored without refrigeration should not be used longer than three months after it is opened. Close attention should be paid to the expiration date on the can. Very old cans of ether often must be disposed of by bomb squads rather than disposal agencies.

Suspect ether can be tested for peroxides with an acidified solution of potassium iodide. A small amount of ether would be poured into a test tube containing a small amount of the test reagent. If a red color appears upon shaking the vial, peroxides have formed. Be extremely careful and contact an expert at once! Also note that if contaminated ether in any type of container is allowed to evaporate, the peroxides will have concentrated in the container, increasing a very real explosion hazard.

To dispose of fresh ether, we recommend letting it evaporate in a safe fume hood (or equivalent.) For large amounts, contact a disposal firm at once. For the reasons stated above, it is not wise to save ether for lengths of time while waiting for a scheduled removal of other waste.

As a footnote, you may be interested to know that law enforcement agencies train dogs to follow the scent of ether because it is used in the manufacture of PCP. The scent of ether often indicates an illicit drug operation to the authorities, so be polite to stray dogs who come to your door.


Another disposal problem nearly unique to the conservator, is the handling of small amounts of PCBs (polychlorinated biphenyls), Arochlor mounting medium. It is absolutely illegal to throw Arochlor into the garbage. Even materials contaminated with PCB, a well documented carcinogen, must never be thrown into the garbage. All materials including contaminated tissues, microscope slides, swabs and so on, should be segregated and disposed of by a registered contractor.

Arochlor is categorized in California as an extremely hazardous material and therefore waste may not be disposed of in this state by anyone other than a registered waste hauler.

Dry Waste

Disposal of solid or dry waste is difficult to discuss in general terms, but as a rule solid or dry materials should be kept in that state and not mixed in with liquid waste for disposal. It may be possible to neutralize small amounts of dry waste before disposal. Seek advice from a professional on particular disposal methods especially for toxic and reactive materials.

Chemical Incompatibilities

Some chemicals are not compatible with others. Chemical reactions are fairly common in waste collection containers. Incompatible materials may burst into flames immediately or hours after mixing; emit noxious or toxic gases; or simply bubble and fizz out of the container making a mess.

As a rule, do not mix or store the following chemical classes together:

Learn about which materials are incompatible when mixed together and which are not. Numerous lists and tables of incompatible chemical types have been compiled. Often chemical and supply catalogues contain such listings (i.e. Conservation Materials or MCB Reagents Catalog.)

The following are specific incompatibilities:

Do not use these chemicals at all:

How To Find Help

Assistance should be available in your area for advice on how to inventory, catalogue, collect, containerize and dispose of hazardous waste. Try looking first in the telephone book for the State Department of Health Services or equivalent, the local fire department, a waste management company or waste hauler. Waste management companies and haulers must be registered with the state and with the Environmental Protection Agency (EPA.) There may be a consultant fee for services rendered.

You will not require the complete services of a large waste management company like the IT Corporation, however IT might be willing to offer some guidance as a community service. It is also possible that you will locate a company which is set to handle small quantities of waste. If a solution cannot be found through the obvious channels, then find out which other nearby organizations generate small quantities of varied waste. A university laboratory or a hospital may have problems similar to yours. Ask them how they have set up a collection/disposal system.

Collecting and Cataloguing for Removal

First take an inventory of the chemicals in the lab. Think about upcoming projects and the type and amount of waste they might produce. These initial steps will help the lab schedule and budget for future waste removal. Waste should be collected in a volume which is cost effective to remove.

It is important to maintain a list of all the materials in a waste container and to indicate approximate amounts. A check list attached to the container might be a simple way to keep track. This information will be needed in order to complete the forms which document waste removal and disposal (see Removal.)

Ask the waste management company or waste hauler you are working with about the type of container they would like you to use and how it should be labeled. In most cases, reusing the glass bottles in which the chemical was purchased will be a convenient solution. This approach postpones the problem of disposing of empty bottles. The original labels should be obliterated or removed and the bottles clearly labeled as waste. Open mouth glass bottles also make suitable waste containers. Glass or plastic is preferable to metal because small amounts of water in the waste will not cause rusting. An advantage to glass or plastic is that it is transparent and you can see what is inside. Teflon or polyethylene containers are good and are less apt to break than glass. Waste bottles should be kept closed unless they are under constant ventilation in a fume hood. As noted earlier, ether should be kept in a metal container.

To minimize the risk of breakage or leakage, waste containers may be kept in cardboard boxes or even better, a wooden crate. The cardboard boxes that solvents are shipped in are quite good for this purpose. For maximum safety these boxes can be lined with polyethylene and filled in with vermiculite or cat litter around the bottles. This fill is an absorbent material which becomes a containable slush if waste leaks or is spilled. Vermiculite is preferable to cat litter because it is inorganic, non-reactive and nonflammable. It is sold at hardware or plant stores. Even though waste has been containerized, incompatible materials must not be put in the same box. As a final precaution, place a small tray under each bottle. This waste is now ready for transport to an intermediate receiver who will pack or prepare the waste in some way for final disposal.

If you have agreed with your waste hauler to have the waste ready for direct transport to a disposal site, get professional advice on preparation of waste materials. You may be requested to use a DOT (Department of Transportation) steel drum. There are several types, so find out which one is appropriate to your needs.

The DOT drum should be filled with vermiculite before adding chemicals which are compatible with one another. Because disposal sites no longer are willing to accept liquid waste, it must be solidified. When mixed with vermiculite, the waste is made into a slurry. Vermiculite acts like a sponge and can hold a limited amount of liquid before it begins to lose excess. A rule of thumb is that 5 parts vermiculite are used for every 1 part liquid. According to the instruction you have received, the waste may be poured in freely and mixed with some kind of paddle which should be left in the drum, or bottles of waste may be placed inside using the loose vermiculite as cushioning. The latter is certainly a neater procedure. If the waste is poured in as free liquid, you are then confronted with the problem of what to do with the bottles. In states which do not exempt small generators, empty containers which once held hazardous materials, must be disposed of as hazardous waste. If your state regulations do not supersede federal law, then a container holding less than 1" of liquid may be disposed of in common garbage. In any case, a properly filled 55 gallon drum will hold about 10 gallons of waste materials. Keep a list of the contents and be aware that the weight and capacity of the drum may exclude you from legally transporting the drum privately.


Now that it is legal in California for the public to transport small quantities of hazardous waste (see Current Legislation), the question is where to take it. There are only a handful of disposal sites in all of California and this state has more than most. Further, the sites which are geared to accept small quantities of varied waste are even fewer. It is probable then, that you will arrange either to leave the waste at an intermediate station or to have a registered waste hauler pick it up. In most cases there is some cost involved.

Contact the local Health Services Department, fire station, waste haulers, waste management companies, or other small waste generators to ask how disposal is handled in your community. If you work at an organization which operates under the auspices of a government agency, that agency should be able to give some guidance or even include the lab (now that they know that it is a waste generator) in its waste disposal system. It is too expensive and cumbersome for a large company like the IT Corporation to send out a truck for your two bottles, but they will probably accept a delivery from you by prior arrangement if the containers are properly labeled and if it is understood how the manifest forms which record the disposal will be filled out. A fee for disposal would be determined on an individual basis. Containerized Chemical Disposal, Inc. operating out of Monrovia, CA is a waste management company specializing in the needs of the small generator. They offer a complete service which includes advice on cataloguing and collecting waste. They pick up the waste on scheduled "milk runs" and pack the waste for final disposal themselves. Charges are set according to quantity and type of waste, but an average cost may be $100-$125.

The Environmental Health Coalition, an environmental advocacy group in San Diego has initiated a pilot project with city and county grant money. This group has organized a program to pick up household hazardous waste free of charge. Currently collection is limited to household waste and pick ups are only made within certain zip codes. The Coalition would like to extend these services to small business, but first must determine their needs. At the end of the pilot project, recommendations will be given to San Diego on how to organize a continuing program. A similar program exists in Sacramento under the auspices of The Golden Empire Health System Agency. The Los Angeles County Department of Health Services has a "Small Generators Program."

Disposal of waste means filling out a hazardous waste manifest which indicates what kind of waste is in the container, who produced the waste, the name of the transporter and how the waste was disposed of. By signing these forms the generator, the transporter and the disposal site all share some responsibility for the waste, however the government always views the waste as being yours. The forms are sent to the Department of Health Services where a copy is kept on file and a copy is returned to the generator describing how the waste was treated. There is an enormous amount of paperwork involved.

The Conservation Center at the Los Angeles County Museum of Art is currently designing a disposal plan for the department's hazardous waste. The WAAC newsletter is interested in publishing any follow up information on this topic. So please write with any questions, comments or findings of your own to either Chris Stavroudis at LACMA or to Caroline Black at 1644 N. Courtney Ave, LA, CA 90046. Dr. Hazelwood has offered to answer questions if you call or write to him at IT Corporation, 23456 Hawthorns Blvd., Suite 220, Torrance, CA 90505, (213) 378-9933.

Caroline Black, Editor
Chris Stavroudis, Los Angeles County Museum of Art

The authors would like to thank Jean Carr, Public Participation Coordinator, Southern California Hazardous Waste Management Project of the Southern California Association of Governments (SCAG) for giving the time and constructive suggestions which helped this article off the ground.

additional keywords: Aroclor

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