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(11) | EP 3 031 986 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | METHOD OF PROTECTION OF GROUND WATERS |
(57) A method of preventing infiltration of excavation pollutants to ground waters characterized
by a 50 cm thick layer of coal gangue, sprinkled with 10% suspension of ash, which
was obtained through bituminous coal combustion, or preferably - brown coal - 5 times
over 10 days, in the amount of 0.3 m3 of suspension per 1 m2 of created surface, which is compacted with a road roller after 50 days and then
covered with at least 50cm thick layer of coal gangue. The excavation is then filled
with coal gangue up to 2m below the planned surface level, while the upper 2-meter
thick later is filled with a mixture of soil from landfill cover and post-fermenting
sludge from agricultural biogas plant in the weight ratio of 9:1.
[0001] The object of the present invention is the method of preventing infiltration of pollutants from mineral resource excavations to ground waters.
[0002] Development of road engineering caused high demand for rock minerals, which led to the creation of huge excavation that degrade large areas of land. Depositing waste in these excavations is one possible way of its utilization. However, the risk of contaminating ground waters by the pollutants leached from the deposits is a hindrance in wider application of this method.
[0003] The Polish patent No. 376141 presented a method of sealing waste deposits which involves the creation of impermeable insulating layer of ash and cement with an in-built layer of vinyl-maleic copolymer, modified with carbonic acid diamide. Utilization of organic membrane, which degrades with time, as well as the use of cement, which doubles the cost of manufacturing the isolation, constitute disadvantages of this method.
[0004] The patent WO1997026416A1 presented the methods involving implementation of layered insulation, comprising a layer of plastic foil, layer of bentonite, loaded with a layer of soil on the top. In this case, plastic foil is also likely to degrade after some time.
[0005] The USA patent No. 5374139A presented the method involving the utilization of geotextile mat (0.6-0.2 pore size), covered with a layer of soil, on which waste glass and gelling agent is poured in order to lower water permeability. Here, geotextile matrix is also subject to biodegradation, which may result in leachates, years after the exploitation period.
[0006] Another method was presented in the German patent DE3466654D1; it involves the use of membrane which is permeable for water, but retains chemical compounds. In this case, there are concerns that membrane pores may clog quickly.
[0007] The essence of the method of preventing infiltration of pollutants from mineral resource excavations to ground waters is that 50cm layer of coal gangue is sprinkled with 10% suspension of ash, which was obtained through bituminous coal combustion, or preferably - brown coal - 5 times over 10 days, in the amount of 0.3 m3 of suspension per 1 m2 of created surface, which is compacted with a road roller after 50 days and then covered with at least 50cm thick layer of coal gangue. The excavation is then filled with coal gangue up to 2m below the planned surface level, while the upper 2-meter thick later is filled with a mixture of soil from landfill cover and post-fermenting sludge from agricultural biogas plant in the weight ratio of 9:1.
[0008] The advantage of this invention is that it prevents infiltration of excavation pollutants to ground waters.
Example.
[0009] A 50 cm thick layer of coal gangue was formed, sprinkled with 10% suspension of ash, which was obtained through bituminous coal combustion, or preferably - brown coal - 5 times over 10 days, in the amount of 0.3 m3 of suspension per 1 m2 of created surface, which is compacted with a road roller after 50 days and then covered with at least 50cm thick layer of coal gangue. The excavation is then filled with coal gangue up to 2m below the planned surface level, while the upper 2-meter thick later is filled with a mixture of soil from landfill cover and post-fermenting sludge from agricultural biogas plant in the weight ratio of 9:1.
1. A method of preventing infiltration of excavation pollutants to ground waters characterized in that a formed 50 cm thick layer of coal gangue is sprinkled with 10% suspension of ash,
which ash was obtained through combustion of bituminous coal, preferably brown coal,
and which sprinkling is performed 5 times every 10 days, in the amount of 0.3 m3 of suspension per 1 m2 of the formed surface, then after 50 days said formed surface is compacted with a
road roller and then covered with at least 50cm thick layer of coal gangue, the excavation
is then filled with coal gangue up to the height of 2m below the planned surface level,
while the upper 2-meter thick later is filled with a mixture of soil from landfill
cover and post-fermenting sludge from agricultural biogas plant in the weight ratio
of 9:1.
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REFERENCES CITED IN THE DESCRIPTION
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.
Patent documents cited in the description