Simulating-optimizing coupled method for pumping well layout at a nitrate-polluted groundwater site

Abstract

The unreasonable pumping scheme of the pump-treat technology can lead to high repair cost and poor performance in contaminated groundwater remediation. In order to improve the cost effectiveness of the technology, we took a heavily nitrate-polluted informal domestic waste landfill site in North China as an example, and optimized the pumping scheme using Visual MODFlOW software combined with genetic algorithm (GA) in MGO module. By designing the constant pumping rate scheme and phased pumping rate scheme, optimal layout of pumping wells were determined with the minimum total pumping capacity as the optimal target. The result showed that the two wells which located near the central axis and in the middle and lower reaches of the plume with a constant pumping rate of 13.2 m3/d and continuous pumping for 75 days was the optimal pumping solution in constant pumping rate scheme. While the pump schedule as Q 1 = 19.8 m3/d, Q 2 = 6.93 m3/d, t 1 = 25 d, t 2 = 50 d express the minimum total water output which was the optimal pumping scheme in phased pumping rate scheme. By comparing the two schemes, it was concluded that under the same governance days, the phased pumping scheme could save 15% of the total pump output compared with the constant pumping scheme.