Technical Field

The solution consists in the method of waste dump isolation at its construction, operation and sanitation or enclosure of the dump's body by means of isolation materials not used for this purpose until now. It concerns the area of waste management that is a part of the environmental protection.

Background Art

One of the means of waste disposal is its dumping. For this purpose, controlled dumps are built at present, the main function of which is to prevent leakage of pollutants that can get to underground waters by extraction of the waste in the dump's body mainly due to rain and subsequent leaking. The underground waters are thus polluted and the pollutants are subsequently getting into the whole chain of plants and animals, threatening thus the environment. The controlled dumps are built after selection of a suitable location thoroughly generally assessing especially the hydrogeological base. After landscaping, which consists in the formation of a suitable profile of the dump, the bottom and walls of the dump are mechanically compacted. The sealing of the dump is achieved through foliation by high-density isolation foils in multiple layers. The individual isolation foils are thermally welded or glued and covered by layers of gravel, soil, clay material and the like, which are gradually compacted. A controlled dump is equipped with a drainage system, a monitoring and control system, which are not the subjects of this submission.

The disadvantages of dumps thus built are the following: Demands laid upon the selection of a suitable location, high laboriousness of its construction, material and financial demands of its sealing system and demands of the expertness and precision of the realisation of the construction. Another disadvantage is the imperfection of the sealing system consisting mainly in:

a) its thickness, which decreases the capacity of the construction, or increases its projected dimensions,

b) the possibility of damage to the isolation layers on slopes of the dump through landslides that are probable after long-term action of atmospheric influences as the dumps are designed for 20, 30 and more years of operation,

c) the risk of the seal's damage by the pressure of the piled-up layers of waste and by mechanical shocks, by the presence of sharp objects under or above the isolation foil, by washout cavities under the foil, by puncture of the isolation foil at the initial dumping of waste by a longer solid object, for example, by a steel pipe, whereby, with the damaged upper isolation foil, the probability of damage to further foils due to the waste extracts, pressure and mechanical shocks at waste dumping and due to subsequent dilatation in the intermediate layer, is high.

Disclosure of Invention

The method of waste dump isolation and its isolation layer is characterised by the fact that the isolation is provided by a polyethylene, polypropylene or other plastic mixture material of a foil character. This material is in a freely laid state placed so that there is 20-150 kg of the material per square meter of the dump's bottom or slope. The plastic material thus placed is then sprinkled by a suspension of a material with non-crawling properties, preferably bentonite, with the concentration of 0,5-3 %-wt., in the amount of 3- 5 m ³ per 1000 m ² of the surface, and pressed by a layer of soil or a similar material to the height of 0,5-1 m. The layer thus created is then covered by a drainage net, which is covered by a layer of gravel with the width o f 0,3 m and height of 0,1 m, and which is then forced to the surface of the isolation plastic layer by a stream of water. After sufficient drying, the bottom's surface is then mechanically compacted by riding it over with vehicles. A layer is thus created on the bottom of the dump that is isolating, water tight and drainage-equipped. Similar isolation layer is then built in stages during the dump's operation. This is done as follows: Rolled plastic material is laid to the foot of the dump's slope and, after even spreading, preferably up to the height of 1,5 m of the free slope, it is covered by a soil material creating thus similar isolation as on the bottom of

the dump. By the same procedure as given for the isolation of the dump's bottom, without applying the drainage, the dump can be covered after discontinuation of its operation. The method of sealing is suitable also for sanitation and re-cultivation of the so called uncontrolled dumps, i.e., dumps without isolation systems, preferably after application of isolation resins by their injecting into the dump's bottom. The installation of the drainage system can be realised also in a different manner without prejudice to the application's usability. The plastic material used can come also from sorted waste, provided that it does not contain pollutants that could have an impact on the underground water's quality, in spite of the fact, that after the compacting of the plastic material using the non-crawling suspension, its extraction is irrelevant. An unsuitable material must be washed to remove the pollutants, which is, however, not the subject of this solution. Sprinkling with as little as 1 % suspension of bentonite or kaolinite will prevent any capillary diffusion of the waste extract between adjacent surfaces of the plastic layer. It will also prevent any capillary elevation of the underground water through the isolation layer in case of its rising above the dump's bottom. The sprinkling will aid the creation of another isolation layer that will be created from colloid particles of the waste extract on the surface of the plastic isolation layer.

The solution according to the description has the following advantages:

Perfect sealing of the dump by a single layer of compacted plastic.

The sealing material is available, it is usually a waste and its utilisation, at the same time, solves the problem of its disposal.

With respect to the perfection of the sealing, the selection of location for the dump is less demanding.

The solution does not exclude usage of another protection layer at any time during the dump's operation, especially if there is a need to dispose of a plastic waste that cannot be used for sealing of another dump.

The solution provides for simple enclosure of dumps filled with waste and sanitation of non-isolated dumps.

It is possible to minimise the leakage of extract from existing uncontrolled dumps and also of dumps with damaged isolation systems by creating the described type of isolation on their surface.

This method of dump isolation can be realised by means of existing technical means used for dump construction.

During the dump's operation, the pollutants will concentrate in the lower horizontal part of the dump and, should there be a need for total liquidation of the dump, they can be easily identified.

Fluctuation of the underground water level or landslides on the slopes have no impact on the tightness of the dump.

A wilful damage of the sealing system cannot be realised by simple puncture as its sealing ability would be restored.

The solution of isolation is, in comparison with presently used means, less expensive, simpler, less demanding with respect to time, machinery and technology.

Description of drawings

The solution will become apparent from the description of a preferred but not exlusive carrying out, illustrated in the accompanying drawings, wherein:

Drawing 1 shows the sprinkling of the spread and folded foil with the bentonite suspension.

Drawing 2 in Detail A shows the continuation of the construction of the dump's bottom. In Detail B, Drawing 2, shows one of the ways of dump drainage.

Drawing 3 shows construction of the dump's slope.

Drawing 4 shows a re-cultivated dump.

Drawing 5 shows possible damages of the presently used isolation made of high density polyethylene.

Drawing 6 in part A shows initial situation in dump isolation's construction. Part B shows the adaptability of the proposed solution to individual influences.

Best Mode for Carrying Out the invention

The attached drawings show actions necessary to isolate the dump, the dump after termination of its operation and re-cultivation, the imperfection of isolation by means of foils, and the adaptability of the proposed plastic isolation layer to the risk factors in a vertical cross-section. Drawing 1 in Detail A shows the initial stage of isolation where 1 is the dump's body, 2 is the plastic foil material ("PFM") after sprinkling with a bentonite suspension, 3 is a foil preventing mixing of the laid soil 4 with PFM. Detail B shows the sprinkling of PFM 2 with the bentonite suspension. Drawing 2, Detail A, shows the first part of PFM layer 5 compressed by soil 4 and the sprinkling of another PFM layer added to the first band when forming the isolation of the dump's bottom. Detail B, Drawing 2, shows working-in of the drainage tubes 6 into the soil layer 4 over the PFM layer 5 by a stream of water, where 6 is the drainage tube enveloped in gravel 7. Drawing 3 shows the formation of isolation of slope where 1 is the body of the dump, 2 is freely laid PFM, 4 is soil, 5 is the layer of compressed PFM, 8 is waste. Detail B, Drawing 3, shows the situation after covering by soil and after formation of isolation on part of the slope of PFM. Drawing 4 shows a re-cultivated dump in vertical cross-section, where 4 is soil, 5 is the isolation layer of PFM, 6 is the drainage tubing, 8 is the waste. Drawing 5 shows, in vertical cross-section, the possibilities of damage to the foil 5 by action of pressure and extract in the presence of a sharp object 0, washout cavity H under foil 2, hard object 12 or by puncture by a longer object 12 while compacting the waste 8 in the dump. Drawing 6 shows the risks of damage to the isolation layer of PFM 5 by a sharp object 10, washout cavity 1_1 under the isolation layer 5, hard object 12 or by puncture by a tube 13. Part A shows the

situation where there is no pressure and shocks acting upon the dump's bottom under the above conditions, and part B shows the adaptability of the isolation layer 5 to the above risk factors.

The invention will be described with an example of concrete procedure for isolation of a dump with a square ground plan and the bottom area of 10,000 m ² :

In a vessel with 40 m of bentonite suspension is prepared by mixing 1250 kg of bentonite with 39,5 m ³ of water by means of air pressure from a tank car. 30 m ² of compressed plastic foil material ("PFM") is laid close to the front slope of the dump along the whole side, that is, 100 m. After releasing, it is then evenly spread to the height of 1,5 m of the dump's slope 1 in the width of

3 m and also 1 ,5 m on the side slopes in the same width. After mixing, the tank car will pump 0,3 m ³ of the bentonite suspension from the reservoir and immediately sprinkle over the band of PFM 2. The band of PFM 2 is preferably covered by a polyethylene foil 3 five metres wide in order to prevent penetration of soil into PFM 2 and thereby their mixing. By means of a loader, 150 m ³ of soil

4 is gradually laid over the band of PFM so that a layer of soil 4 is created 0,7 m high and approximately 2 m wide over PFM 2 and so that a i m wide band of PFM 2 is left not covered by the soil along the whole length. This is followed by loading always 21 m of PFM 2, of which 3 m wide band is created in a similar manner, evenly, including covering of the side slopes 1 up to the height of 1 ,5 m. This band is then sprinkled over by 0,4 m ³ of the suspension in the described manner, leaving again 1 m wide band of PFM 2 not covered by soil 4. The procedure is then continued up to the opposite slope 1, where it is then continued similarly as in the beginning of the procedure. After working-in the drainage 6 and levelling of the surface, the soil layer 4 and PFM 2 are compacted by riding over by means of the vehicles used.

The procedure for sealing of the slopes 1: Waste 8 is laid to the dump 1 so that there is always a clearance of at least 0,5 m between the dump's slope 1 and waste 8. This clearance is then filled by compressed packs of PFM 2 along the whole edge of the dump 1 After loading of a 1 m layer of the waste 8,

the total perimeter of the dump 1 will be approximately 420 m. In total, 60 m ³ of PFM 2 is laid to the space between waste 8 and slope of the dump 1 along the whole perimeter. After releasing the packs, PFM 2 will be sprinkled over evenly by 1 ,8 m ³ of 3 %-wt. bentonite suspension and, along the whole perimeter, the PFM 2 will be covered by 500 m ³ of soil 4 by a bulldozer so that a 0,1-0,15 m thick layer of isolation 5 is created to the height of 0,5 m above the level of waste 8.

List of reference marks for the drawings:

1. body of the dump, slope of the dump

2. plastic material with the character of a foil (PFM)

3. auxiliary foil

4. soil

5. isolation layer (formed according to the solution)

6. drainage piping

7. gravel

8. waste

9. high-density polyethylene foil

10. shaφ object

11. washout cavity

12. hard object

13. pipe, rod