ARCHIVED REPORTS_2010 - Laserfiche WebLink

Home Browse Search

n 6.1 General The vertical expansion of the landfill will increase the vertical loading on the existing leachate collection pipes in Modules 1,-3, and 4. Therefore, pipe loading calculations have been performed to verify that the existing leachate collection pipes can support the additional vertical loading without structural failure. Pipe loading calculations have also been performed to design the leachate collection pipes in the future modules. The pipe loading calculations have been performed using an improved method based on the procedures recommended by McGrath (1998a and 1998b). The improved design method accounts for: (i) the vertical stress -dependent modulus for the bedding material, and (ii) modification of the vertical load due to arching effect. The pipe loading calculations using the improved method are outlined in Koragappa (2005). The structural design calculations performed for the leachate pipes include, estimation of the ring deflection, check for wall buckling and crushing, and estimation of the circumferential strain. The leachate collection pipes within each module include both lateral and header pipes. Although the header pipes used within each module have slightly larger diameter relative to the corresponding laterals, they have the same standard dimension rations (SDR). Hence, from structural design perspective, both pipes are identical. The laterals typically run perpendicular to the landfill perimeter; whereas the header pipes run parallel to the landfill perimeter and are located close the landfill perimeter. As a result, the interior end of the lateral pipes will be under significantly greater heights of waste than the header pipes. Therefore, the pipe loading calculations have been performed only for the more critical lateral pipes in each module. 6.2 Check of Existing Pipes 6.2.1 Existing Leachate Pipes in Module 1 The existing maximum waste height above the critical leachate pipe within Module 1 is approximately 115 feet. A review of the final grading plan for the proposed vertical expansion of NCRC&SL in conjunction with the base grading plan for Module 1 shows that the maximum waste height above the most critical leachate collection pipe will increase to approximately 148 feet. Therefore, pipe loading calculations have been Geotechnical Analyses for NCRCSL Department of Public Works/Solid Waste Shaw Environmental, Inc. County of San Joaquin, December 12, 2007 6-1