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<Sourcebook of Alternative Technologies for Freshwater Augumentation in East and Central Europe> 1.8 Lining of Solid Waste Disposal Sites Technical Description As the standard of living increases, the quantity of resulting waste increases as well. In Hungary, it is estimated that 20 million m³ of solid waste is produced annually. However, only 14 million m³ is collected for disposal at identified disposal sites. The fate of the remainder is unknown, but may be assumed to be informally disposed of outside of the identified disposal sites. This informal disposal continues for various reasons, including distance from formal collection and disposal systems, cost of disposal, nature of the materials being disposed of, and tradition. Hence, domestic waste disposal is not a simple issue, even though it is ubiquitous in nature. Serious problems in waste management exist throughout the region. The usual waste disposal site is a simple pit or natural depression in the land surface into which refuse is dumped without any engineering or pollution prevention measures being considered. Such dumps can contain everything from harmless substances (such as food waste) and reusable materials (such as paper and plastics) to extremely hazardous chemical wastes (such as printers waste, machine shop chemicals, and spent solvents and cleansers). There have been several attempts to organise selective collection of wastes within the region, but most have had little success to date. Establishment of an engineered landfills is also a common method of waste disposal, designed to control the emissions of, particularly, hazardous substance to the environment. The overall design of secure waste disposal facilities should include control of the top of the waste pile to minimize atmospheric emissions and infiltration of precipitation (i.e., capping), and control of the bottom of the waste pile to maximize the collection of lecheate and minimize contaminant transport through the bottom (i.e., sealing). The facilities typically are designed, and sites selected, in response to individual soil characteristics on the sites, and the more modern facilities are isolated from the underlying groundwater by various lining materials. Similarly, waste piles are also isolated from surface infiltration by the placing of an impervious cap at the top of the pile. Guidelines for the selection of lining and capping materials for specific sites have been published in the relevant technical literature; however, lining and capping options include mineral sealing layers (clay linings and caps) and multiple layer seals (clay linings and caps combined with high density polyethylene geomembranes). Such linings act to minimize releases of contaminants into the environment, and to control seepage from the landfills so that contaminants leaching from the landfills are treated and enter the environment at an acceptable or non-detectable rate. Within the region, communities are moving from the use of traditional dumps to secure landfill technologies. For example, the City of Nyíregyháza, Hungary, when faced with a serious waste disposal problem caused by the old, unprotected dump site being filled to capacity, decided to create an environmentally-safe landfill for the disposal of non-recycleable solid wastes. This facility was constructed adjacent to an existing landfill near Nyíregyháza-Oros, and the first, 245 000 m³ capacity phase of the project opened during 1984-85. The second phase of the project is intended to increase the capacity of the site constructed under phase one, providing for up to 12 years of waste disposal capacity. A key feature of the new waste disposal system is the elimination of the reusable and recyclable wastes from the waste stream. Such elimination will help to prevent the transformation of wastes into polluting materials which could potentially pose an environmental threat to the inhabitants. A further feature of the new waste disposal system is the use of a lining and drainage system to protect the Pleistocene aquifiers found in the area. The landfill was constructed with a four-layer, composite lining with a drainage system for the collection of lecheate, a monitoring system with sensors and monitoring wells, lighting, and protective landscaping. The lining system was constructed with the following layers: a soil layer to protect against mechanical damages, a leachate collection zone, a primary barrier layer of 2 mm PHDE (High Density Polyethelene) GUNDLE® geomembrane made with double seam welding and control channels including an electrode-based damage detection system, and a CONSOLID® clay mineral sealing layer with an infiltration coefficient, K, of between 1 and 5 x 10-9 m/s. This lining system was installed over a graded subsoil base. The original clay mineral seal was a 25 cm thick layer of clay placed under the primary sealing layer. Due to technological developments adopted by the contractor, CONSOLID Ltd., the thickness of this clay seal has been reduced to 12 cm by using a clay mixture consisting of clay and the additives C 444® (1%), Solidry ® (4 kg/m²), and sand. These additives provide additional control of contaminants that may pass through the primary sealing layer. Leachate is collected by a drainage system placed beneath the waste pile, and is re-used to irrigated to the top of landfill, from which it evaporates, to control dust formation. The monitoring system provides continuous assurance of the integrity of the primary seal. In the event that this integrity is compromised, the sensor network can help to identify the exact location of the damage with an accuracy of about 150 mm.
Figure 2. Cross-section of a composite liner system. Extent of Use This technology has been used at newly-constructed waste disposal sites in Hungary, Poland, and Latvia. Operation and Maintenance The technology does not require specialized operation and maintenance provided that the landfill has been proper planned and constructed, with adequate pollution control measures provided. Depending on the materials disposed of in the landfill, however, it might be necessary to undertake limited repairs in the event of the liner being punctured. Generally, the cost of the maintenance is met by local government from fees collected for the waste collection and disposal. Level of Involvement This technology is typically implemented at the municipal level, but may be implemented by industries generating large volumes of solid wastes. Costs In the Hungarian example, the construction cost of the landfill was $608 000. The sensor system, provided in addition to the site construction, cost an additional $32 000 or 1$/m2. Effectiveness of the Technology This technology is effective in protecting groundwater and surface water resources from pollution. Suitability This technology is suitable for use at most municipal and industrial waste disposal sites. Advantages This technology provides for the protection of water resources. If combined with a leachate collection and pumping system, this technology can also minimize dust formation from solid waste disposal sites. Disadvantages There are no known disadvantages to this technology if it is properly sited and installed. Cultural Acceptability This technology is culturally acceptable. Further Development of the Technology Identification of less costly sealing materials could accelerate the use of this technology. Promulgation of appropriate solid waste disposal regulations and standarization of siting and design criteria would be very important complementary actions supporting the use of this technology. Information Sources Petèr Kovac and Dr Kornèlia H.
Kocsis, Felsö - Tisza - Vidèki Környezetvèdelmi
Felügyelösèg, 4400 Nyiregyhàza, Szèchenyi
u. 19, Hungary, Tel. (36-42) 310 155, fax: (36-42) 310 713.
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