RU2259895C1 - Method of making polygons for storing domestic waste on permafrost soils - Google Patents

Abstract

FIELD: dumping solid waste.

SUBSTANCE: method comprises trenching during the period of the beginning of soil freezing and laying heat and hydraulic insulation on the trench bottom and over the trenches during the period of the beginning of defrosting soils. The trenches are then filled with solid waste, and during the next period of freezing, the trenches filled with solid waste are trenched from both sides.

EFFECT: improved environmental protection.

5 dwg

Description

The invention relates to the construction of permafrost (MPM) complexes of environmental structures designed for storage of solid household waste (MSW).

A known method of erecting trenches for storage of solid waste, when the base (bottom) of the trench in climatic zones where the formation of filtrate is possible, should be buried at least 0.5 m in clay soils ("Hygienic requirements for the design and maintenance of landfills for municipal solid waste SanPiN 2.17.1038-01 "). The limitations of the considered method in relation to MSW landfills for permafrost is the lack of facilities to prevent the filtrate from entering the bottom of the trenches, its removal and to protect permafrost from thawing.

Closest to the proposed method is a method of erecting trenches for storage of solid waste with the collection and disposal of the filtrate. "Instructions for the design, operation and reclamation of landfills for solid household waste", approved by the Ministry of Construction of the Russian Federation on 5.11.1996 - Moscow, 1996. According to this scheme, the filtrate clarified in a dirt trap flows by gravity to a pump station and is pumped into a system of perforated pipes with further spillage filtrate over the surface of intermediate maps of the landfill covered with intermediate insulation.

As the disadvantages of the known method, the following can be listed:

- the formation of leachate at the bottom of the trenches due to the lack of devices that prevent atmospheric precipitation from entering the trenches;

- thawing of soil in the summer;

- lack of additional cooling of permafrost;

- low reliability of the filtrate collection and disposal system - failure of the transfer pumps, interruptions in the supply of electricity can lead to overflow of trenches with the filtrate.

The limitations of the prototype method also lies in the fact that it can only be used for the construction of solid waste landfills on thawed soils. For the construction of the mentioned landfills on permafrost soils, especially high-temperature thermodynamically unstable, the known method cannot be applied.

The technical result of the invention is to increase the effectiveness of protection against pollution of soil and ground water of solid waste by eliminating the possibility of ingress and accumulation of filtrate at the bottom of trenches, as well as protection against thawing of rocks.

The essence of the invention consists in the fact that in the method of erecting solid waste landfills on permafrost soils, including marking and excavation at the site of the trench landfill, they are excavated at the beginning of soil freezing, then layers of thermal and waterproofing are installed at the bottom and during the beginning of thawing of soil on top of the trenches, after that the trenches fill the MSW, and in the next period of freezing, excavate the trenches on both sides of the trenches filled with the MSW.

The claimed technical solution differs from the prototype in that, as elements that increase the efficiency of protecting soils and groundwater from pollution by solid waste landfill on permafrost soils, they are additionally cooled with subsequent layers of heat and waterproofing, and the bottom and top of the unfilled trenches are insulated the period of the beginning of thawing of soils.

The method of construction of solid waste landfills on permafrost soils can be explained as follows. It is known that the continuous distribution of the permafrost layer, which is, in essence, an ideal water storage site, determines the effective natural protection of groundwater and soil from the penetration of pollutants into them. On the other hand, the possible thawing of permafrost is the cause of the environmental risk associated with the pollution of environmental components. This is especially true for high-temperature permafrost, which are essentially thermodynamically unstable cryogenic confines. Changes in the temperature regime and thermal state of the rocks caused by the development of the grounds of the base of the landfill and the storage of solid waste will lead to an increase in the average annual temperature and the gradual formation of taliks. Infiltration of precipitation into the trench will cause filtration degradation of the permafrost. It should also take into account the increase in soil temperature due to the biochemical decomposition of solid waste. Considering that concentration of pollutants occurs in the seasonal thaw layer and permafrost waters, and their conservation in the thickness of the permafrost layer, this situation is unacceptable. This is due to the further development of technogenic geocryological processes leading to a deterioration in the quality of the natural environment and the emergence of environmental risk zones.

Thus, natural cryogenic confining at the landfill site will not be able to provide reliable protection of groundwater and soil from pollution without the use of special measures.

The main objective of these measures is, at a minimum, to preserve the natural temperature regime of the permafrost and, as a minimum, to lower their temperature to values that ensure the stable state of the rocks as a cryogenic confinement. To this end, the upper layer of the permafrost layer, which is in close proximity to a possible source of thermal influence (the bottom of the trench), is subjected to forced cooling (freezing). The remaining layer of seasonally thawed soil is also subjected to freezing. Thus, the temperature regime of the soil of the base of the trenches becomes less susceptible to the warming effect of atmospheric air and solid waste stored in the summer. To completely eliminate the mentioned influence on the roof of the permafrost, as well as to prevent their filtration degradation, in addition to freezing the base of the trenches, heat and waterproofing of their bottom and top is arranged. The insulation of the top of the empty trenches should be temporary - until it is loaded with solid waste with the subsequent installation of a permanent insulating layer.

Thus, the creation at the base of the trench of zones with lower temperature values (compared with the natural temperature regime), as well as the use of permanent thermal and waterproofing of the bottom and temporary, over the trench, is a preventive measure for the conservation of permafrost with the aim of eliminating environmental risk when constructing solid waste landfills according to the trench scheme on high-temperature permafrost. Unlike the prototype, where the formation of leachate at the bottom of the trench is allowed, the ingress of warm air into them, as well as the possible thermal effect of solid household waste on the surrounding soil mass, in the claimed method, the warming effect on the permafrost of air, leachate, and solid waste is excluded.

Figure 1 shows the open trench 1, a layer of clay soil 2, the position of the upper boundary 3 of the permafrost at the beginning of the development of the trench, additional cooling of the trench in winter with cold air 4.

Figure 2 shows the insulation layer 5, the waterproofing layer 6, the insulation of the top of the trench 7.

Figure 3 shows View a in figure 2.

Figure 4 shows a trench 8 filled with municipal solid waste 9, a permanent insulating layer 10.

Figure 5 shows the open trenches 1 located to the left and right of the longitudinal axis 11 of the trench 8, additional cooling of the trenches 1 in winter with cold air 4.

The method is as follows:

based on the actual annual receiving capacity of the landfill, the required number of trenches and their parameters (length, width, depth and slope laying) are determined;

on the site of the landfill determine the location of the required annual number of trenches for storage of solid waste taking into account that the trenches of the next year of operation of the landfill are located to the left and to the right of the longitudinal axis of the trenches of the previous year;

with the beginning of the freezing of the soils of layer 2, a trench 1 is excavated to the design level of its bottom, located above the boundary of the permafrost 3;

trenches are left open throughout the winter period. In trenches, due to the lowering of the elevation of the natural relief, the conditions of heat transfer on the soil surface change and it is cooled (frozen) by cold air 4;

with the beginning of the thawing of the soils of layer 2, the trench 1 is cleared of snow and at its bottom arrange layers of heat-5 and waterproofing 6;

to prevent warm air and atmospheric precipitation from entering trenches 1 during the summer period, surface isolation in the form of portable gable shields 7 is arranged above the trenches;

loading MSW 9 in the trench 1 is as follows. In order to reduce the warming effect of the air on the permafrost and to prevent atmospheric precipitation from entering the trench, the solid waste 9 is laid and compacted with a bulldozer in trenches that are open only before installation. The opening of the trenches is carried out by removing portable gable shields 7. The bulldozer shifts the MSW 9 into the trench with their layer-by-layer compaction. For this, the bulldozer is moved along the trench 1. After filling the trench of the MSW, it is closed with a constant insulating layer 10, for example, clay soil obtained during the development of the trench 1;

with the beginning of the freezing of the soil layer 2 to the left and right of the longitudinal axis 11 of the trench 8, filled with municipal solid waste 9, develop soil for the device of the trench 1;

trenches are left open throughout the winter period. In addition to cooling the intrinsic bases of trenches 1, additional freezing of the base of trench 8 occurs;

with the beginning of thawing of soils of layer 2, trenches 1 located to the left and right of the longitudinal axis 11 of trench 8 are cleaned of snow and layers of heat-5 and waterproofing 6 are arranged at the bottom of each of them;

to prevent warm air and atmospheric precipitation from entering trenches 1 during the summer period, surface isolation in the form of portable gable shields 7 is arranged above the trenches;

further procedures for laying, compaction and isolation of solid waste in trenches are similar to the procedures of the first trench.

In the present invention, the positive effect is as follows:

- elimination of the possibility of ingress and accumulation of leachate at the bottom of the trenches;

- reduction of the warming effect of atmospheric air and municipal solid waste on permafrost;

- improving the reliability of cryogenic confines due to a further decrease in their temperature and the possible transfer from plastic-frozen to hard-frozen;

- reduction to a minimum of environmental risk associated with the operation of solid waste landfills on high-temperature permafrost.

Claims (1)

A method of erecting solid domestic waste landfills on permafrost soils, including marking and excavation at the site of a trench landfill, characterized in that the trenches are excavated at the beginning of soil freezing, then heat and waterproofing layers are installed at the bottom and on top of the trenches at the beginning of thawing of soils, after that, the trenches are filled with municipal solid waste, and in the next period of soil freezing, trenches are excavated on both sides of the trenches filled with municipal solid waste.

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