in the Chemical laboratory
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Edited by N O R M A N V . STEERE, 140 Melbourne Ave., S.E. Minneapolis, Minn. 5541 4
1x11. Chemical Waste Disposal at the University of Minnesota J O H N W. TESKE, Instructor ond Safety Engineer, School of Public Heolth, University of Minnesota, Minneapolis, Minn. 5 5 4 5 5 HISTORY
3. University fitudents and employees were beine umteoessrtrilv exposed to
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hnsardous waste, either during storage or thrangh improper or clandestine disposal methods. An example of this is two plumbers who spent one day in the hospital for abservation aft,er being overcome by ehemiesl emissions from an open floor drain. Or, as another example, students in some laboratories were unnwaro that chemicals in the nearbv
T h e TJllivemity of Minnesota has been y s m s in the use :tci.ively engaged f o ~many . of chemicals n i d other iub~lnneeswhich are hnznrdow due lo their flammability, toxieilp or explosiveness. Ileeords do not indieate previmls disposal methods, but as far hark 3.3 1958 a disposal problem wm recognixed lleeent observations indicate thnl i n some ir>stancesthe materials were not disposed of htlt were allowed to accnmulale in lahorntories and storerooms. C l ~ e m i d shave been foimd in Yome lalmrntories which were placed there beforo the +,urn of the cent,my. 111 all lildihood t,hc ot,her rnnterisls were either flnshed down the sewer or sent. with the rcgolar refuse to he incinemtd oor buried i n n lnrnlfll. Neither of lhese methorl of disposnl sre amsidered adequate due l o h n ~ a r d or pollniioo prohlems involved. Exploration fol. new mcthodr of disposing of bhe chemical waslrs was hw!m i n earnest nhont 1 OF0 and various indiv~doals, inclnding the mlthor, have contrihoted to what is presently the ncrepted disposd method of hxmrdol!s chemical waste a1 the University of Minnesots.
PROBLEM DEFINITION The pn~blemsinvolved with the disposal of hasnrdom chemical w a t e s are:
1. Chemicals, explosives and unusable compressed gns cylinders have acatrnulnted over the years in laboratories nud storeroomq, due to a. lack of concern and/or method of disposal. Many kilograms of um~sedand u11wanted explosive and/or toxic chemicals have been found to red in Universit,~of Minnesota huildioes.
j ~ ~ r i o ~tol s t,he waste handlers, or which produced pollution problems and was sometimes illegal. An example of- t,his is the disposal of flammable liquids in the sanit3;ry sewer, which produces explosion hazards and is contrary to the Minueapalin Plumbing, Water, Gas and Piping Ordinance snd the bIinoespolis Sewer Ordiusnee. Also, many other hsaardons materials were only diluted as the.y passed through the snnituy sewer and sewage trest,ment plant on the way to the river, and later appeared in the drinking water snpply of the inhabitants downriver.
Volume 47, Number 4, April 7970
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storemom had become shack-sensitive due to extended periods of storage and could have exploded if mishandled.
DISCUSSION This article does not deal with the disposal of biological or radioactive waste, but with the ordinary chemicals u e d day-to-day in laboratories. Two methods of disposal were examined. The first method was by incineration with a burner nozzle for flammable waste and a burning chamber for solid waste. It became readily apparent, however, that thie method would be nnsatisfaotory due to incompatibility of the large variety of ehemicnls involved. Nany of the chemicals, when combined, will produce either fire or explosions which could destroy tho incinerator and injure :he workers. The economics of employing qualified personnel to oversee this type of operation were also prohibitive, as were the capital coks of the inci~lerstor. See Appendix A fur :\ listing of typical waste chemicals. The second disposal method involves the use of open pit disposal, which is a modification of recognized landfill operations. Suitable nersounel ~ r o t e e t i n ntech..
n l s ~presented a unique problem, since some of them were corroded on the erterior nnd i t was difficult to ident,iiy the contents or to determine whether they were full or empty. Ilirect burial of the cylinders whs considered, but the prohlem of eventa.tlhreakdow~~ of the cylinder doe to oorrosioh could have resulted in a public nuisance or toxicialogy problems in th6 future due to the compressed gas escaping back i,o the surfaoe. Therefore, i t was decided to rupture the cylinders in a remote area with explosives and then bury the scrap met,al. See Appendix B for a list of t,ypieal compressed gas cylinders disposed of each year. The disposal of explosives created only a problem of transporting them t,o a remote area and obtaining qualified personnel to detonate them. See Appendix C for a list of explosive.
THE DISPOSAL SYSTEM One of the primary considerations in designing the system is making it convenient. Therefore, a regular Friday pick-up of waste chemicals and other hazardous materials was established. A new chemical labeling system being iuitiated s t the Universil,y of Minncsata also carries a reminder that the chemicals should not he disposed of ill building drains. See example. The University of Minnesota Rosemount Research area was selected for the disposal location due to remote location, geology and water table level. Soil borings indicate about 1.2 m (4 f t ) of glacial drift over about 30 m (100 ft) of sand and gravel. The water table is (Continued on page A295)
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sistent with existing technology. Future advances in solid waste disposal or serious
PURIFIED PETROLEUM BENZIN PETROLEUM ETHER Boiling range 30-60" C
ANGER! Extremely flammable Keep away from heat, sparks, end open flame. Keep container closed. ' Ure with adequate ventilation. *. Avoid prolonged breathing of vapor. FLASH POINT -57O C. Avoid prolonged or repeated contact with skin. (-70" F.) Do not dispose of in building drains
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about 27 m (90 f t ) below the surface, so ground water pollution problems are minimized. An abandoned drainage ditch was plugged a t both ends and surrouuded with a. chain link fence. The fence is intended to eliminate scavenging and the requirement for immediate back-fill. The life of t,he trench for disposal is thus extended. Portable hlast shields were designed and located a t the edge of the pit to protect the workers during dumpi~lgoperations. The chemicals are carried from t,hevmio~m locations a t ilie University by pick-up truck, dumped in the pit, and ignited with a railroad flare. Approximately 25,000 1 (6,500 gal) of liquid solvents and 010 kg (2,000 lh) of solid chemicals are disposed of in the pit each year. The remainder of the ditch is used for' lnndfill of approximately 91 kg (200 lh) of pesticides and .insecticides each year. Eventually, the drainage ditch will be completely back-filled. Compressed gas cylinders are taken to a nearby barrow pit, for disposal. Cylinders with identifiable contents are segregated from unident,ifiable or highly toxic cylinders. Cylinders with identifiable contents are placed in stacks of seven or eight and bhen ruptured with 2.3 kg (5 lb) of TNT. The scrao is used for landfill. f i : ~ lt~ mri r rylitairri Thr ~ ~ t ~ ~ d m ~ i highly , t w piwed HI 11.1. I n ~ t ~ wd n :t t ~ w r l rnull w l h i v ~~Iurrv . :,t.t. pln(:ed i n the in,ttr,rn of a trench and explosive charges are placed on them in such a manner so as to rupture them on the top side and drive the scrap into the ground. The trench is then back-filled. Approximately twenty cylinders a. year are disposed of in this manner. The disposal of explosives is conducted in the same barrow pit in a manner similar to t,hat of the cylinders. The explosives artre placed in a pile and detonated with the assistance of several kilograms of TNT. I n one case a huge crater xhoot 1.2 m (4 ft,) d e e ~resulted from ex~losivedis-
CONCLUSION The present method of disposing of waste chemic:tls a t the University of Minrresots was developed due to uecessity to satisfy ;ru existi1,g need far a. new disposal method and therefore should be considered an experimental project eon-
APPENDIX A Typical chemicals routinely disposed of in the disposal pit. .4leohol Ether Chloroform Acetone Xylene Hexme Varnish Waste oil Benzene Acetyl chloride Casein Pentane alpha Naphtol Fuming sulfuric acid Silver methane arsenate Sodium malonate
Aniline hydrochlorxte Acetic anhydride Trichloracetic acid Pyridme Nitrabeneene Paint waste Miherd oil Toluene Sodium sulfate Tetrazoliom Phosphorus pentoride Alkaline copper tartrate Kerosene Butanol Soda lime Acetic soid
APPENDIX B Typical types of compressed gas cylinders handled through disposal system. Acetylene Chlorine Ammonia Cyclopropane Argon Ethylene oxide Bromine Freon@-12 pentafluoride Helium Bromine trifluoride Hydrogen Butane Nitrogen Carbon monoxide Oxygen Carbon tetrafluoride
APPENDIX C Typical explosives handled through the disposal system. Nitromethane I-Nitroso-2-naphthol Nitroethane Cobalt nitrate Nitropropane Calcium Lead nitrctte Sodium Sodium nitrate Potassium Picric acid Trinitrotoluene 2,4-Dinitrophenyl- Benzoyl peroxide hydraeine Ether peroxides Hydraline Gun powder compounds Dipiclylamine
