| Coal-fired power plants occupies an important position in the power industry inChina, which cuases huge coal fly ash and slag emissions that has reached2.5billiontons. A large amount of ash pile will produce assignable influence to the groundwaterenvironment.With the impact of atmospheric precipitation and water leaching,pollutants in ash will infiltrate into the groundwater via the vadose zone,which causesdeterioration of regional groundwater water quality,even threat on the surroundingresidents health, the production and living water, different levels losses on regionaleconomic, leading to serious consequences. Simulation and prediction of thegroundwater pollution in ash field can provide a scientific basis for utilization ofgroundwater reasonable protection. Based on the study of geological andhydrogeological conditions in the study area,this paper established thehydrogeological generalized model of the study area,forecasted the groundwatersystem effects caused by Anwen power plant ash filde through the groundwaternumerical analysis software Visual Modflow,and concluded that following results:1. Triassic limestone and shale are mainly composed in the study area. From theeast side to the west side of the Dahegou ash field area,the emergence stratum isJialingjiang Formation of Lower Triassic(T1j), Feixianguan Formation(T1f),YulngshanFormation(T1y).The study area is located in north west wing of LiangHeKou syncline,extending to north west wing of Yangchatan anticline, with the folds open and faultsnot developed.2. The study area mainly accepts atmospheric precipitation and lateral recharge,flows out into the minimum erosion basis Daojiaogou River. Karst is medium developed.,and the groundwater is mostly of fissure type. The formation atYangcChaTan anticline axis is the second,third member of the YulongshanFormation,limestone and marlstone,which is relative aquifer. The formation at northwest wing of LiangHeKou syncline is the first, second member of the JialingjiangFormation,limestone and marlstone,which is aquifer. Surface crack is well developedand well versed in,and with the increase of depth it turns out to be that the fracture offormation is weak andaquosity also gradually weakened. Groundwater quality is goodin the study area,with the main hydrochemical type as HCO3－Ca and HCO3－Ca·Mg.3. Pollutants are migration in all directions in the groundwater aquifers,indicating that dispersion and convection is significant to the solutemigration.Formation of pollutant migration is like the shape of ellise with the longaxis along the pollution flow. Formation of pollutant in surface is small,which iscaused by the fact that the ash filed is low-lying. Therefore, the primary controlfunction for pollutants migration flow is convection in the study area.4. Simulation results to high concentrations of SO42-and low concentration of Cl-show that the pollutants concentration plays an important role in pollutant diffusion.In a same period, the higher concentration pollutants moves faster in both thehorizontal and vertical direction, and pollution formation greater than the smallconcentration pollutants. Therefore, reducing the pollution concentration is effectivemeasures to protect the groundwater environment.5. Formation permeability plays an important role in pollutant migration. In thehigher permeability formation, pollutant vertical migration distance is relativelylarge.In lower permeability formation,pollutant vertical migration distance issignificantly reduced.At the same time contaminant migration also has a decreasingtrend in the horizontal direction in low permeability formation.6.The model based on the karst aquifer equivalent fracture aquifer obtainedsatisfactory results.As a result,under the condition of karst with medium or weakdevelopment, fracture and good penetration, the same phreatic surface ofgroundwater and groundwater seepage and hydrodynamic conditions stable, we canmodeling the equivalent fracture aquifer to simulate numerically. |
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