1/12/2023 0 Comments Que es minitubeFIGURE 4 Backfilling with waste In-place behaviorįor horizontal LFG collection, the flow and the head loss in the minitube blanket are governed by the minitubes (the head loss in the geotextile layers being negligible). The size and weight of the waste compactor, as well as the length of the compactor teeth, should be considered when designing the thickness of the initial waste layer over the geocomposite. A minimum of 3 feet (0.9 m) of selected waste should be placed on top of the geocomposite prior to operating a compactor over the area. Waste is placed directly over the minitube blanket ( Figure 4). FIGURE 3 Connection of the minitube blanket to the collector pipe Nevertheless, some specific measures will be taken to manage the condensates (gradation of the support with a slope away from the manifold, condensate drain at one end of the manifold, etc.). Due to its limited thickness and its low hydraulic conductivity in contrast with the surrounding waste, the minitube blanket network won’t obstruct the downward leachate flow into the waste mass and reduce the potential for plugging the perforated LFG collectors. The minitube blanket is unrolled directly on the waste and connected to a collector pipe using connectors specially developed to fasten the pipes from the composite to the collector pipe ( Figure 3). This is a significant loss of airspace and waste disposal tipping fees during the lifetime of a landfill. Common spacing between horizontal LFG collectors is about 50–100 feet (15–30 m) horizontally and 30–40 feet (9–12 m) vertically. Therefore, for most applications, the applied combined reduction factors for tubular drainage geocomposites are almost half of those applied to standard geonet geocomposites (Maier and Fourmont 2013).Ī roll is typically 13-feet (4-m) wide and it replaces a 3-foot (0.9-m) wide × 6.5-foot (2-m) deep trench filled with aggregates surrounding a 6-inch (150-mm) diameter perforated high-density polyethylene (HDPE) pipe. 2010) because they don’t experience geotextile intrusion into the drainage conduits (the minitubes) and no creep in compression of the minitubes when confined. They are compliant with ASTM D7931, Standard Guide for Specifying Drainage Geocomposites, and are defined as multilinear drainage geocomposites in ASTM D4439, Standard Terminology for Geosynthetics.Īn important characteristic of tubular drainage geocomposites is that they maintain their transmissivity under significant normal stresses (Saunier et al. Tubular drainage geocomposites have been used in landfill applications around the world for more than 25 years. The minitube blanket is comprised of 1-inch (25-mm) corrugated polypropylene perforated pipes spaced on 10-inch (250-mm) centers between two nonwoven geotextile layers ( Figure 2). FIGURE 1 Minitube blanket installation Minitube blanket description and installationĪs this technology differs from more common solutions, it is important to first describe the product to be used. This paper presents the significant advantages of using a tubular drainage geocomposite for LFG collection as compared with traditional horizontal LFG collectors ( Figure 1). Traditional methods of LFG collection can be time-consuming and expensive to install, and installation sometimes can be delayed due to seasonal and budgetary issues. The success of an LFGTE project is directly related to the performance of the GCCS. Also, LFG can be processed into a compressed or natural gas for home heating or vehicle use, respectively. LFGTE projects can have design lives in excess of 20 years and range in size from a few kilowatts to 10 megawatts or more. In general, LFGTE projects use the LFG to fuel specially designed turbines, reciprocating engines or boilers. Because of the energy potential of the methane gas, landfill gas-to-energy (LFGTE) projects have been developed to capitalize on renewable sources of green fuel. The collected LFG is typically sent to a destruction device, such as a flare, where it is combusted, and the methane is converted to carbon dioxide. Typically, LFG is controlled by an active vacuum blower system, which extracts LFG through a network of horizontal collectors embedded in rock-filled trenches inside the waste. The need to install a gas collection and control system (GCCS) is dependent on the amount and type of waste accepted. The management of LFG at landfills is an important, and often costly, operational aspect of a well-run landfill.
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