1986-12-08_GENERAL DOCUMENTS - M1977493 (2)

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•I� 7 V i fl• • • ble during the 1969 and subsequent inspections was that considerable Noticeable g breakage of the surface crusts was caused by people walking on and digging into the tailings. The 1970 inspection showed that during the year, an addi- f about 20 ainly in those areas that tional disruption o Percent had occurred, m � were broken the previous year. The 1972 inspection indicated that a total of about 40 percent of the dike showed disruption, but the crust on the pond area ?I' Little difference was noted in the effectiveness of the two appeared unbroken. Id ; chemicals tested, whether on acidic or basic material. The prime reason for the disruptions was physical and unrelated to the stabilizing chemical used. A preliminary conclusion is that chemical stabilization can be effective for an indeterminate time if the proper preparation of the site is accomplished prior to application of the chemicals and maintenance is done each year. Vegetative Stabilization S '�4r;• ' is ' Consideration of esthetics and renewability generally favor use of vege- t'! tative stabilization. However, the successful initiation and perpetuation of :4,: • vegetation on fine wastes involves ameliorating a number of adverse factors. �i;,!,. 4 Mill wastes usually (1) are deficient in plant.-nutrients, (2) contain exces- a7;� sive salts and heavy metal phytotoxicants, (3) consist of unconsolidated sands windblown destroy young plants by sandblasting and/or burial, and ; that, when ; . (4) lack normal microbial populations. Other less easily defined problems ; also complicate vegetative procedures. The sloping sides of waste piles. _ receive greatly varying amounts of solar radiation depending on direction of i t exposure. Studies by Gates (3) have indicated that , while the sun is shining, ,'i ' j or under high temperature conditions , photosynthesis may almost stop. Further- # more, most accumulations of mill tailings are light in color and may reflect r;t excessive radiation to plant surfaces , thus intensifying physiological }I; stresses. Other mineral wastes may be extremely dark in color and absorb excessive heat which may inhibit germination or kill seedlings. For these reasons , vegetation that may be effective on northern and eastern exposures may not be suitable for southern or western exposures. • Ideally, vegetative stabilization should produce a self-perpetuating plant cover directly or foster entrapment and germination of native plant seeds which will form a self-regenerating community. In the latter case, an j =l ecological succession would be established leading to a vegetative covering so completely in harmony with the environment that irrigation or special care would be unnecessary. If the area were not cropped or grazed, only a minimal additional fertilization should be required because the essential nutrients i would be largely cycled in place. Research indicates that , other than the excessive acidity, basicity , or ► salinity, perhaps the greatest problem to be overcome in establishing vegeta- tion is that of windblown sands. Several procedures are in use for preventing windblown sands from covering or cutting off the growing plants. These include water sprinkling while the plants are growing, covering the tailings with soil or country rock, hydroseeding, using excelsior-filled matting as a cover directly over the tailings, and a combination chemical-vegetative pro- cedure developed by the Bureau of Mines. Sprinkling, soil covering, hydro- seeding, and matting have all been proved on various types of wastes , and the