The Scrap Tire Problem

Over 242 million scrap tires are generated each year in the United States. In addition, about 2 billion waste tires have accumulated in stockpiles or uncontrolled tire dumps across the country. Millions more are scattered in ravines, deserts, woods, and empty lots. Scrap tires provide breeding sites for mosquitoes which can spread diseases and large tire piles often constitute fire hazards. Most tire and solid waste professionals agree that a tire problem exists. 

Tires are breeding grounds for mosquitoes. Besides the major nuisance of mosquito bites, mosquitoes can spread several serious diseases. 

Uncontrolled tire dumps are unsightly and are fire hazards. Fires in tire dumps have burned for months, creating acrid smoke and leaving behind a hazardous oily residue. A few tire fire locations have become Superfund sites. 

Tires should be utilized to minimize environmental impact and maximize conservation of natural resources. This means reuse or retreading first, followed by reuse of the rubber to make rubber products or paving, and then combustion and disposal. At present, the preferred uses do not accommodate all the tires, and disposal must be utilized to a large degree. 

Disposing of waste tires is becoming more expensive. Over the past 20 years the average tipping fees for disposing of tires have continually increased. This trend is likely to continue as landfill space becomes more scarce. 

---

Stark, J., in The Tire Recycle Solution Minnesota s Answer to the Scrap Tire Problem, Tire Technology Conference, Clemson University, Oct. 28-29, 1987. 

Goddard, H. C. 1992. Incentives for solving the scrap tire problem through existing markets. Journal of Hazardous Materials, 29, 165-177. 

While artificial reefs do not hold the potential to solve the scrap tire problem, they do have the potential to consume more than they consume now. Currently there are an estimated 120,000 to 150,000 tires used annually in constructing reefs. The goal of Cape May and Ocean Counties is to construct reefs with about 200,000 tires annually. Currently they are doing about 60 percent of this. One estimate of national potential is between one and 1.5 million tires used yearly (16). This is much higher than current levels because only two counties are actively constructing... 

An integrated solution is needed to the waste tire problem. Both government and industry need to work together to develop markets for scrap tires and to ensure proper disposal of those tires that are not recycled and are not incinerated for their energy value. In the next two sections of this chapter, options for mitigating the scrap tire problem are discussed. 

As reported in Chapter 1, 23 states have responded to the scrap tire problem by issuing laws that specifically address this problem. An additional 13 states have regulated tires under provisions of other laws, for instance solid waste laws. As of January 1991, an additional 7 more were in the process of drafting or proposing scrap tire laws or regulations (12). 

Following are additional regulatory and non-regulatory options which have been suggested to help mitigate the scrap tire problem. Some of these have been... 

Education and promotion is an important component of any program to alleviate the problems of waste tires. Audiences that may need to be informed about one facet or another of the scrap tire problem include individual citizens, environmental groups, tire dealers, corporations, those who are or would like to be involved in businesses related to scrap tires, potential users of scrap tire material, and representatives of local, state and Federal government. 

Most of the technologies available for mitigating the nation s scrap tire problem are limited by both economic and noneconomic barriers, and it is often difficult to separate the two. For example, the use of retreaded or used automobile tires is limited by competitive new tire prices, an economic barrier, as well as consumer concerns about safety and reliability, a noneconomic barrier. Designing tires to last 100,000 miles or more would cost considerably more and also would likely result in rougher rides and more tire noise. 

Part I of this book discusses markets for scrap tires including major issues of the current problem, market barriers, and options for dealing with the waste tire problem. Part II discusses using tires for fuel and tire pyrolysis. This part focuses on use of scrap tires as a primary fuel for dedicated tire-to-energy facilities and as a supplemental fuel for cement pants, electric utilities, pulp and paper mils, and other industrial processes... 

Retread industry. Retreaded tires basically extend the nsefnl life of the original tire and thereby tend to alleviate the scrap tire disposal problem. The retread industry would be of interest for the nonpassenger-tire segment (e.g., trucks, buses). It is obvious that if additional retreaded tires were used, the problem of scrap tire disposal would be further reduced, and a more efficient utilization of the natural resources would be realized. Based on the use of retreaded truck and airplane tires, it is technically and economically feasible to utilize retreaded tires. However, the general public considers a retreaded tire an inferior product, which is true to some extent and, moreover, for a good quality retreaded tire, a sound tire carcass is needed [3]. 

E. Goodrich have burned a 10% tire chip mixture with coal (11—13). Tire grinding size reduction problems and deflvery costs have stymied projects based on combined tire and coal fuel. Transportation of tire scrap can cost 0.05 /kg, exclusive of grinding costs, thus tire-fired boilers are limited to areas with sample scrap tire suppHes, eg, large cities or tire manufacturers. The cost of burning one metric ton of tires per hour in an incinerator was ca 0.20—0.40 per tire in 1974, which increased to 0.35—0.70 per tire in 1987 (14). 

The management of scrap tires has become a growing problem in recent years. Scrap tires represent one of several special wastes that are difficult for municipalities to handle. Whole tires are difficult to landfill because they tend to float to the surface. Stockpiles of scrap tires are located in many communities, resulting in public health, environmental, and aesthetic problems. 

This report discusses the problems associated with scrap tires and identifies existing and potential source reduction and utilization methods that may be effective in solving the tire problem. Barriers to increased utilization and options for removing the barriers are identified and evaluated. 

Seven cement kilns in the United States utilize about 6 million scrap tires per year to replace conventional fuels. Cement kilns appear to be ideal for scrap tires because of their high operating temperatures (2,600 F) and good conditions for complete combustion, which minimize air pollution problems. Also, there is no residue, since the ash is incorporated into the cement product. Of the 240 cement kilns in the United States, about 50 are equipped with precalciner/preheaters, making them most suitable for tire combustion. 

If markets for char cannot be developed, the char becomes a major solid waste problem. Analysis of char from the pyrolysis of scrap tires does not indicate a problem with hazardous materials.4 However if it must be disposed of in a landfill, the char should be collected in plastic bags and shipped and disposed of in steel drums to prevent additional fugitive emissions during transportation and disposal. 

Scrap tires present unusual disposal problems. The very characteristics that make them desirable as tires, long life and durability, makes disposal almost impossible. The fact that tires are thermal-set polymers means that they cannot be melted and separated into their chemical components. 

---