Traditionally a landfill s construction involves large quantities of natural materials such as clay (waterproofing), gravel (drainage) and sand (filter and separation). These materials are scarce in the environment and are difficult, expensive and slow to place, especially on slopes. In the rehabilitation of Saida s dumpsite (Lebanon), discussed in this case study, the final design was based on the placement of a drainage geosynthetic for leachate collection and a geomembrane for waterproofing. TABLE 1. REHABILITATION OF SAIDA DUMPSITE DATASHEET JOB: REHABILITATION OF SAIDA DUMPSITE COUNTRY: LEBANON CLIENT: AL-JIHAD FOR COMMERCE & CONTRACTING PRODUCTS: INTERDRAIN GMG 512 MANUFACTURER: INTERMAS NETS, SA AND JUTA A.S. CONSTRUCTOR: AL-JIHAD FOR COMMERCE & CONTRACTING INSTALLER: GLOBAL INTERNATIONAL ENVIRONMENTAL COMPANY For over two decades geosynthetics manufactured by Intermas Nets have been used in landfills (new landfills and cappings) with great success around the world due to their many advantages over natural elements: Geosynthetic s reduced thicknesses allow a greater volume of operation of the Landfill. They can be installed in steep slopes. Due to their low weight they significantly reduce surcharge on waste. Waterproofing and flow capacities are homogeneous as they are industrial products. Comfortable, quick and easy to install and they require no heavy equipment. They are a better solution for the environment, constituted by safe, non-polluting and recyclable materials.
SCOPE Saida dumpsite is located in the southern part of the city of Saida, at the sea front, only 200 meters from nearby residences and commercial units. The city urban areas are closely surrounding the landfill site at a distance of several hundred meters. Managed by the Municipality of Saida, the dumpsite used to receive, until its closure for rehabilitation in 2013, about 300 tons of solid waste per day from 15 municipalities (approximately 250,000 people). The waste mountain covers an area of 60,000m² and it used to be an enduring eyesore and health threat to local residents and tourists. The environmental repercussions were severe; occupational hazards related to incoming health care waste, recurring waste slides into the Mediterranean Sea, and stench which invited countless complaints from local fishermen and residents, in addition to official complaints from the neighbouring island of Cyprus. The Dumpsite had no basal lining barrier and no leachate collection system. SOLUTION This rehabilitation project, promoted by the United Nations Development Programme, aims to solve an environmentally unacceptable situation and to use the land again for the benefit of the Saida municipality. The procedure of the rehabilitation is Landfill Mining which includes a treatment of excavated waste at site to produce secondary construction material complying with local and EU standards. The landfill s design includes the use of drainage geocomposites for: Leachate collection in the new cell of the landfill (base and slopes). Rainwater drainage in the capping of the landfill (base and slopes). As well, the design includes geomembrane for waterproofing in the new cell and the capping. TABLE 2. MATERIALS, THICKNESSES AND FUNCTIONS OF THE DIFFERENT CAPPING LAYERS IN THE REHABILITATION OF SAIDA DUMPSITE MATERIAL THICKNESS PRODUCT FUNCTION Waste 32 m - - Soil 20 cm - Regularization and protection Drainage Geocomposite 1 cm INTERDRAIN GMG 512 HDPE Geocomposite 1 cm Junifol PEHD Filter+Drainage (leachate)+ Waterproofing. Protection. Collects leachate Waterproofing. Prevents leachate to infiltrate in the ecosystem Natural Clay - - Waterproofing. Natural clay layer
USED PRODUCTS Leachate collection and rainwater drainage INTERDRAIN GMG 512, a product manufactured by Intermas Nets, was placed as a leachate collection layer (base and slopes of the landfill) and rainwater drainage layer (capping of the landfill). It is constituted by a high density polyethylene (HDPE) geonet and 2 polypropylene (PP) geotextiles heat-bonded to the net. The geonet is formed by two over-crossed strands at 60º, whose geometry creates channels with high flow capacities even under high pressures and at very low gradients (placed almost horizontally). TABLE 3. INTERDRAIN GMG 512 MAIN CHARACTERISTICS PROPERTY UNIT INTERDRAIN GMG 512 STANDARD Mass per unit area g/cm 2 890 ISO 9864 Thickness at 2 kpa/200 kpa mm 5,8/5,2 ISO 9863-1 Peak tensile strenght MD/CD kn/m 20/17 ISO 10319 Elongation at break, MC/CD % 40/50 ISO 10319 Flow capacity (MD, i=1, H/H) - - - s=20 kpa l/sec m 1,16 ISO 12958 s=50 kpa l/sec m 1,03 ISO 12958 s=200 kpa l/sec m 0,74 ISO 12958 s=400 kpa l/sec m 0,48 ISO 12958 Geotextile opening size mm 170 ISO 12956 The geonet s main function is drainage while the geotextile acts as waterproofing protection, filter element and fine particle anti-pollutant. The main reasons why INTERDRAIN GMG 512 was selected are: High flow capacity. High tensile and crush resistance which allow usual construction loads (vehicle traffic, compacting process, tensions due to land disposal, etc) without any damage in the product. Excellent creep and fatigue behavior that guarantees a long-term drainage solution. Durability. PP and HDPE are chemically inert, imperishable and not sensitive to saline water or microorganisms. Waterproofing The landfill s waterproofing was carried by placing a high density polyethylene geomembrane manufactured by Juta as. Junifol PEHD is a 1.5 mm geosynthetic geomembrane commonly used in waste storage and disposal sites. This geomembrane is smooth in the flat areas and texturized in the slopes to increase stability. Junifol s main characteristics are: Guarantees full waterproofing of the new cell. Rolls available in widths up to 8 m. Stabilized against UV radiation. Withstands the effects of chemicals, acid, alkaline and salt solutions and are not affected by mildew and microorganisms.
TABLE 4. JUNIFOL HDPE 1.5 MAIN CHARACTERISTICS PROPERTY UNIT JUNIFOL PEHD STANDARD Density g/cm 3 0.94 EN ISO 1183 Thickness mm 1.5 EN 1849-2 Surface - Smooth (base) Texturized (slopes) - Permeability to liquids m 3 /(m 2 d) U= 1.75 10-6 D= 1.66 10-6 EN 14150 Tensile strenght (MD/CD) N/mm 2 30/30 Elongation % 800/800 EN ISO 527-1,3 Specimen Type 5 Puncture resistance kn 4.5 EN ISO 12236 Tear strength N/mm 140 ISO 34-1 INSTALLATION PROCESS The steps followed in the installation process were: Installation of Junifol PEHD geomembrane. In general, seams must be oriented parallel to the line of the maximum slope. The membrane must be overlapped prior to seaming to affect a good weld and allow for proper testing with a minimum overlap of 7.5 cm. Placement of INTERDRAIN GMG 512 for leachate drainage. In case of adverse climate conditions (wind) it is convenient to join the geotextiles with a hot-air gun to prevent lifting. Minimum geotextile overlap is 10 cm. Extension and compaction of a soil layer for regularization and protection of the geosynthetic package. This soil layer covered INTERDRAIN immediately after its installation, avoiding possible problems with adverse climate conditions (wind). Waste disposal in the rehabilitated cell.
CONCLUSIONS Drainage geocomposites manufactured by Intermas Nets and geomembranes manufactured by Juta guarantee all the important characteristics in landfill rehabilitation: Complete waterproofing. Rainwater drainage. Leachate drainage. Long-term performance of the landfill. The use of geosynthetic products in this project certifies: The use of INTERDRAIN drainage geocomposite and Junifol PEHD waterproofing is suitable for their application in new cells of landfills. Geosynthetic installation is fast, easy and economic. INTERDRAIN s flow capacities and Junifol PEHD s waterproofing capacities are reliable,homogeneous (industrial products) and can substitute gravel and clay layers respectively (products with heterogeneous characteristics). Geosynthetics usage in landfills is a better environmental option because PP and HDPE are non-polluting products and 100% recyclable. On the other hand, large quantities of natural materials are needed, which are scarce elements in nature and whose extraction creates a great environmental impact.