processing stage required to produce the new fuel from the original refuse consumes more and more energy. As a result, the maximum net energy delivery approaches half of the original energy in the refuse. We also would quarrel with some of the more specific conclusions later in the article. There seems to be no justification for the statement that CEA's Eco-Fuel "will generate as much steam as pulverized coal on an equivalent weight basis." The heating value given is 6900 Btu/lb which is considerably lower than coal's. Furthermore the com bustion loss associated with the latent heat of water in the flue gas would be significantly higher. The operational excess air level is not given for the double vortex burner and therefore relative flue gas cannot be estimated. Another point that should be taken more seriously is density. At 7-10 lb/fts, shredded refuse is not particularly storable or transportable. Its potential utilization thus is severely restricted. We do believe in energy recovery from wastes. However, until projections and plans are put on a realistic basis-which considers the negative as well as the positive aspects-very little real progress is going to be made. Alfred C. W . Eggen Ronald Kraatz K T. Lear Associates, Inc.
Manchester, Conn. 06040 Waste oil recovery
Dear Sir: In general the subject matter of the meeting, The First International Conference on Waste Oil Recovery and Reuse ( E S & T , April 1974, p 310-311), was covered quite well. However, the "specifications for re-refined oil" as set out in the block table are not technically correct, and, by implication, misrepresent the capabilities of re-refined oils and may be grossly misleading to readers not familiar with the detail of lubricant formulation. The SA, SD, SE grades listed in the table refer to the API Service Classifications for automotive engine oils. Series 3 refers to a diesel engine oil specification developed by Caterpillar Tractor. Oils meeting these specifications must pass carefully defined engine tests and other laboratory tests. Meeting the requirements of these tests demands a careful formulation of base oil and additives. The properties listed in the table do not represent the specifications for the API Service Classifications, nor should the conclusions be drawn from them that used oils can be re-refined to meet any of these service requirements. No test data were available at the conference to demonstrate that rerefined oils produced by current processing methods can be formulated 596
Environmental Science & Technology
to meet defined quality. This is a lack which needs to be filled. Unfortunately, the testing is relatively expensive. And even for products formulated with virgin base oils, a given specification is limited to base oil from one specific source (i.e., one refinery and one general type of crude oil). These limitations become prohibitive with respect to the variable input and relatively low volume output of a single re-refining plant. I t is likely that re-refined oils can be formulated with additives to achieve desired performance levels, but it should not be assumed that this can be accomplished by fiat merely by direct substitution of rerefined base oils for virgin base oils in a successful new oil formula. The proper and advantageous use of socalled "waste" oil is a worthy problem, but it is not a simple one. S. M . Darling
The Standard Oil Co. (Ohio) Cleveland. Ohio 44128 Solid waste information
Dear Sir: I should like to tell your readers about a service that I have recently utilized and found to be helpful in my environmental studies. This service is the Solid Waste Information Retrieval System (SWI RS) run by EPA's Office of Solid Waste Management Programs. The address for this service is: SWIRS, P.O. Box 2365, Rockville, Md. 20852. Recently. I sent a letter to SWIRS requesting information on participation of the public in solid waste management decisions and activities. I received a packet of materials in response which is apparently the u$ual response to inquiries. The information package included: a selection of abstracts of periodical and nonperiodical publications retrieved from the SWlRS data bank; xeroxed materials concerning relevant EPA grant and contract activities; and general reference materials. Each abstract had a complete bibliographic citation. In addition, I received, later, a number of books and pamphlets from the OSWMP publications office. I found the information that I received from SWIRS to be very useful. The abstracts sent to me had obviously been selected according to their relevance to my own interests. In addition, the people at SWlRS are very prompt: I received a response to my inquiry within two weeks of the date that I mailed it. Since receiving my materials, I have mentioned SWIRS to a number of my colleagues and have found that very few of them had heard of it. I am writing this letter in t h e hope that you will be able to help me inform your readers of this valuable service that they should often be able to find useful. The services of SWIRS are available free of charge. I believe that SWIRS is set up to
handle inquiries which concern the economic and management aspects of solid waste handling, scientific and technical questions, and areas of public concern on environmental matters. Jeannette McConnell Glassboro, N.J. 08028 Mining industry
Dear Sir: The article on coal mine waste and acid mine drainage ( E S & T , Feb 1974, p I l O ) , left out some critical points. The most hazardous problem associated with coal waste has been its impoundment of water. In 1972, a coal refuse dam built by Pittson Co. in West Virginia to settle and filter wastewater from its coal-cleaning operation, burst, drowning 126 people.. These inherently unsafe impoundments are unneccessary, since alternate means of treating coal preparation wastewater are economically available. Another point concerning coal waste is that, due to the recent increased demand for coal, some companies have found it economical to recover coal from old refuse piles, while at the same time reclaiming the area. Acid drainage from abandoned mines remains the biggest pollution problem of the coal industry. Mine seals are usually ineffective and sometimes hazardous. A possible answer to both the coal waste and acid drainage problems is to put coal waste underground. Coal waste can be returned to active mines either in empty shuttle cars, or piped in a slurry form or by compressed air. Coal waste slurry can be injected through boreholes into abandoned mines. Filling the underground void with waste can be expected to greatly reduce acid formation by cutting down the available air along with water infiltrating from roof fractures. The fact that research has never been done on the extent to which acid is controlled by this method, is very unfortunate. Mine backfilling with coal waste was practiced over 100 years ago in Pennsylvania, and is done in one Utah coal mine today, as well as practically all mines in West Germany and Holland. Finally, our organization resents the implication of your article that strip mining is necessary, and that opposition is based on purely aesthetic values and irrational fears. We invite the author to visit a strip mined West Virginia hollow during a heavy rainstorm and observe for himself the landslides, increased flooding, and water pollution which are regular occurences in these areas. All of this destruction is unneccessary because over 9 5 % of our recoverable coal can only be deep mined. Ed Light
Campaign Clean Water Charleston, W.V. 25322
