Wellbore effect and its influence on contamination monitor well-a case study on groundwater monitor well around landfill
XU Ya1,2,3, LIU Yu-qiang1,2, HU Li-tang3, LIU Jing-cai1, DONG Lu1, NAI Chang-xin1
1. Research Institute of Soil and soliid Waste, Chinese Research Academy of Environment Sciences, Beijing 100012, China;
2. China State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China;
3. Engineering Research Center of Groundwater Pollution Control and Remediation of Ministry of Education, Beijing Normal University, Beijing 100875, China
A representative conceptual model for water flow and contaminant transport in the aquifer-monitoring well system under the condition of leachate leakage was constructed. The Equivalent Hydraulic Conductivity (EHC) method was used to describe the water flow and head distribution in the dual-medium system, while the ADE equation and the 1-D solute transport equation for pipe flow were, respectively, used to simulate pollutants migration and distribution in the aquifer and in the wellbore, and eventually a governing equation describing the distribution of pollutants in the monitoring well-aquifer system under leachate emission conditions was constructed. A finite-difference method for this equation was developed based on the Fortan platform. This program was then used to simulate and analyze the effects of monitor well on the regional flow and solute movement in the interior and around the monitoring well, as well as its influence of the wellbore on the flow and solute transport. The results show that The wellbore effect affects the local groundwater flow field and the concentration field around the hole, which leads to the concentration increase in the inner and lower parts of the borehole, and the decrease of the concentration in the certain area outside the wellbore; the effect of the wellbore effect decreases with the increase of the distance. from well to leakage point. The monitoring error caused by the wellbore effect is not more than 20% when the distance is greater than 2times the thickness of the aquifer. The influence of well diameter on wellbore effect is rather complex, not monotonic. In this case, wellbore effect increases with the increase of well diameter, reaches the maximum at 0.1m, and then decreases. The greater the permeability coefficient of the aquifer and the greater the specific storativity, the smaller the influence of wellbore effect. Therefore, the effect of wellbore is less in the gravel and coarse gravel media aquifers with strong permeability and greater porosity, and the effect of wellbore effect on the monitoring effect is greater for the weakly osmosis or medium permeability sand and sand clay aquifers.
徐亚, 刘玉强, 胡立堂, 刘景财, 董路, 能昌信. 填埋场井筒效应及其对污染监测井监测效果的影响[J]. 中国环境科学, 2018, 38(8): 3113-3120.
XU Ya, LIU Yu-qiang, HU Li-tang, LIU Jing-cai, DONG Lu, NAI Chang-xin. Wellbore effect and its influence on contamination monitor well-a case study on groundwater monitor well around landfill. CHINA ENVIRONMENTAL SCIENCECE, 2018, 38(8): 3113-3120.
Rodrigo G V, Felipe M R, Jordi C, et al. Hotspot detection and spatial distribution of methane emissions from landfills by a surface probe method[J]. Waste Management, 2016,55:299-305.
[2]
Dan A, Masao O, Yuta F, et al. Removal of heavy metals from synthetic landfill leachate in lab-scale vertical flow constructed wetlands[J]. Science of The Total Environment, 2017,584-585, 742-750.
[3]
Jun W, Hua Z, Pin-Jing H, et al. Insight into the heavy metal binding potential of dissolved organic matter in MSW leachate using EEM quenching combined with PARAFAC analysis[J]. Water Research, 2011, 45:1711-1719.
[4]
Guifang W, Gang L, Pinghe Y, et al. Genotoxicity assessment of membrane concentrates of landfill leachate treated with Fenton reagent and UV-Fenton reagent using human hepatoma cell line[J]. Journal of Hazardous Materials, 2016,307:154-162.
[5]
Han Z Y, Ma H N, et al. A review of groundwater contamination near municipal solid waste landfill sites in China[J]. Science of The Total Environment, 2016,569-570,1255-1264.
[6]
Paul F, Hudak U. Locating groundwater monitoring wells near cutoff walls[J]. Advances in Environmental Research, 2001,5:23-29.
[7]
Canadian Council of Ministers of the Environment. National Guidelines for Hazardous Waste Landfills[Z]. 2006.
[8]
Bashi-Azghadi S N, Kerachian R. Locating monitoring wells in groundwater systems using embedded optimization and simulation models[J]. Science of the Total Environment, 2010,408(10):2189-2198.
[9]
Mogheir Y, Singh V P, de Lima J. Spatial assessment and redesign of a groundwater quality monitoring network using entropy theory, Gaza Strip, Palestine[J]. Hydrogeology Journal, 2006,14(5):700-712.
[10]
Reed P, Minsker B, Valocchi A J. Cost-effective long-term groundwater monitoring design using a genetic lgorithm and global mass interpolation[J]. Water Resources Research, 2000,36(12):3731-3741.
[11]
Yenigül N B, Elfeki A M M, Gehrels J C, et al. Reliability assessment of groundwater monitoring networks at landfill sites[J]. Journal of Hydrology, 2005,308(1):1-17.
[12]
Khalil A, Almasri M N, Mc Kee M, et al. Applicability of statistical learning algorithms in groundwater quality modeling[J]. Water Resources Research, 2005,41(5):1-16.
Bennett G D and Patten E P. Constant-head pumping test of a multiaquifer well to determine characteristics of individual aquifers. U.S.[J]. Geological Survey Water-Supply, 1962,1536:181-203.
[19]
Giddings T. What is an adequate screen length for monitoring wells? Opinion I. Ground Water Monitoring Review, 1987,7(2):96-97.
[20]
Church P E, Granato G E. Bias in groundwater data caused by well-bore flow in long-screen wells:Groundwater, 1996,34(2):262-273.
Chen C X, Jiao J J. Numerical simulation of pumping test in multilayer wells with non-darcian flow in the wellbore[J]. Ground Water, 1999,37(3):465-474.
Blaschke A P, Derx J, Zessner M et al. Setback distances between small biological wastewater treatment systems and drinking water wells against virus contamination in alluvial aquifers[J]. Science of the Total Environment, 2016,573:278-289.
[26]
Hu L T, Chen C X, Chen X H. Simulation of groundwater flow within observation boreholes for confined aquifers[J]. Journal of Hydrology, 2011,398(1/2):101-108.
Eungyu Park, Zhan H B. Hydraulics of a finite-diameter horizontal well with wellbore storage and skin effect[J]. Advances in Water Resources, 2002,25(4):389-400.
