Study On The Influence Of Key Parameters Of MSW Landfill Leachate Pumping Well System On Leachate Level Control

Many old landfills and expanded landfills in China are plagued by high leachate level.The higher leachate level in landfills will adversely affect the stability of municipal solid waste landfills,landfill gas collection efficiency,groundwater quality.It is necessary to control the leachate water level below the safe range.For landfills without installation of leachate drainage system or failure of leachate drainage system,the establishment of leachate pumping well is the most common engineering measure to control the leachate water level in the landfill.Based on the current research needs of leachate pumping well system,the main contents and results of this paper are as follows.(1)According to Slimani et al.(2017)leachate pumping and injection test,a numerical calculation model of leachate pumping well is established,and the well pumping flowrates is set according to its field test working conditions.The calculation results reproduce the measured water level results well,and verify the accuracy of the numerical model.(2)Based on the calibrated numerical calculation model,the permeability characteristics of waste body,the height of landfill,the geometric size and spacing of leachate pumping well,and the influence of key parameters such as pumping flow rate on the leachate pumping well are studied.The effects of various parameters on the water level in the well and the water level distribution in the landfill are obtained.The greater the pumping flow rate of the well,the lower the leachate water level in the well and in the garbage heap.The greater the well spacing,the saturated permeability coefficient and the anisotropy value of the waste body,the higher the leachate water level in the well and the garbage heap.The larger the well radius,the gravel layer hydraulic conductivity and the thickness of the gravel layer,the higher the leachate level in the well and the lower the water level in the garbage heap.The intermediate cover soil will hinder the collection of leachate flow into the well,so that the leachate level in the well is reduced,and the leachate above the middle cover layer is difficult to be extracted,which is an unfavorable factor affecting the leachate pumping well.(3)Based on the key parameters affecting the well water level height of the leachate well pumping system,the response surface method for calculating the well water level of the leachate well pumping system is established.The predicted value of the response surface formula is compared with the model calculation results and the field measured values.The calculated results of the formula are in good agreement with the model calculated values and the measured results,and the applicability of the formula is verified.