Prediction And Evaluation Of Groundwater Contamination For X Petrochemical Works In Panjin

With the collection of geological and hydrogeological data,this paper carried out the information analysis,field investigation and identification of environmental factors.A 1:50000 Scale of hydrogeological mapping of the study area was worked out with the supplement of necessary survey and tests.The water level measurement and the monitoring and evaluation of water quality in different seasons were done.Through the above work,the environmental hydrogeology,the pollution source and the exploitation and use of groundwater in study area could be figured out.Then the environmental risk evaluation during the operation period was started with the foundation of the groundwater flowing and transporting model.At last,serials of advice about the seepage control measures were raised.The main results as follows:1.The present situation of environmental hydrogeologyAccording to the water-bearing medium,formation conditions,storage feature and the vertical and horizontal regularity of change in study area,the groundwater can be divided into the pore-space water in loosening rocks(Q4)and the pore and Fracture of Interlayer water(Q3).The pore-space water in loosening rocks(Q4)was widely distributed in the Quaternary layers of the plain,which provided a broad space for pore-space water.Further,it could be grouped into phreatic-micro artesian water and confined water.The main aquifer of the phreatic-micro artesian water is the midium-fine sand and silty sand,thickness from 32 to 60 m,permeability coefficient from 2to 5m/d,buried depth from 0.4 to 2.7m,medium-rich water-bearing,and water yield of single borehole from 200 to 1000 m3/d with 5 meters deep drawdown.The confined water is widely distributed under the shallow layers.The rock type of confined aquifer is silty sand,midium-fine sand,medium coarse sand,fine sand and sandy gravel with soil,thickness from 60 to 150 m,permeability coefficient from 0.98 to 10.01m/d and water yield of single borehole from 100 to 1000 m3/d with 5 meters deep drawdown.The present groundwater quality evaluation picked 8 groundwater sampling points and 25 factors in a hydrological year in study area.The evaluation results showed the TDS,CODcr,Cl-,Mn of most water sites were beyond the III Class of the Quality standard for ground water in China.The SO42-,F-,NH3-N and Fe of these wells occasionally exceeded.Other pollution such as Hg and heavy metal ions did not surpass the level.2.The impact of groundwater environmentThe prediction result of groundwater pollution showed during the construction and operation process,the project made no discernible effect on the groundwater environment.This paper carried out the solute transportation of different pollution in 10 potential pollution scenarios.The results showed during the service period,the pollution had no impact on the river near the factory.There existed a certain influence on the shallow groundwater;the depth only reached 30 m.Under the break pipelines of the project,the pollution plume would arrive 60 m depth of the aquifer and did not cross the shallow aquifer.3.The pollution prevention and control of groundwater environmentAccording to the conclusion of groundwater environmental impact evaluation,specific seepage control measures were carried out.The measures were technically feasible and economic rationality.