Optimal Groundwater Remediation By Pumping Scheme Based On A Simulation-optimization Model

Pumping and treat technology(PAT) as a groundwater remediation technology,for it can remediate a variety of contaminated groundwater quickly and efficiently, iswidely used at home and abroad.The design of PAT requires determined of welllocation, pumping rate of each well, the time for pumping and other factors whichbased on investigation of hydrogeological conditions and the pollutantscharacteristics.Because the widespread method to design a PAT is processingalgorithm or engineering experience. For an actual groundwater remediation project,it is difficult to achieve optimal design goals.This study is based on a chemicalcompany site groundwater remediation project in northern China, through theGMS-MGO method modeling and optimizing the groundwater PAT remediationproject. The single-well pumping rate limits, well location and number of wells on theimpact of optimization results also be analysed.Finally, a appropriate scheme aboutthe PAT of the groundwater remediation was proposed.Groundwater flow and contaminant simulation results show that the maindirection of groundwater flow is from the northwest flows southeast.The coking plantand depot area have a high concentration of benzene. The contaminant plume ofbenzene has a poor mobility. Through1740d of the natural degradation, benzene inthe coking plant groundwater can reach repair goal. Sensitivity analysis showed thatthe most important factor impact the groundwater flow model is permeabilitycoefficient, and the degradation factor is the most important factor for contaminanttransport model.According to the technical requirements of PAT method, select the application ofthe PAT groundwater remediation technologies in the coking plant. Optimizationresults show that when given a fixed well location and number of wells, keeping otherconditions unchanged, for this study, with the pumping time increases, the totalpumping capacity decreases; continue to increase pumping time, will lead to furtherreductions in the concentration of constraint points with a total pumping capacityincreases.Keeping other factors unchanged, different wells location, well numbers andsingle well pumping capacity were compared, the result show that: Well location doesnot affect the shortest recovery time, centralized distribution of the wells will lead to a smaller total pumping capacity; the fewer of the number of wells, at the sameremediation time, the total pumping capacity will be smaller and the shortest recoverytime will be longer. Fewer wells benefite cost saving, and more wells benefite timesaving. For this study, based on restoration project requirements, select less time torepair. In a word,18wells with centralized distribution be applied, the repair time is600d, the pumping volume is2.35×106m3.Before optimizing the design of groundwater PAT by MGO method, agroundwater flow model and a contaminant transport model should be construct. andevery time you need to set the appropriate limit value of single well pumping capacityto ensure after optimization the contaminant concentration in the region close to theremediation goal. Moreover, the iterations in the MGO program need to be set as aappropriate value by trial. If the iterations is too small, optimal result cannot bereached. And if the iterations is too large, it is computationally intensive for optimize.In this paper, practical case studies show that GMS-MGO simulation optimizationmodel can easily and effectively optimize the design of pollution of groundwater PAT.