Buffering distance between hazardous waste landfill and water supply wells in a shallow aquifer

• Published in: Journal of cleaner production 2019-02, Vol.211, p.1180-1189
• Main Authors: Ya, Xu, Jingcai, Liu, Lu, Dong, Yuqiang, Liu, Weishi, Li, Changxing, Nai, Qifei, Huang
• Format: Article
• Language: English
• Subjects: Health risk; Leachate; Monte Carlo; Safe drinking
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2018.11.161

The vulnerability of engineering barrier and the toxicity of leachate increase the need to maintain a certain buffering distance between landfill and drinking water sources. In order to provide decision-making support and technical guidance for the determination, and management of buffering distance, this paper coupled the dose-response model, leakage estimation model, exponential decay source model, and the advection-dispersion model for contaminants transportation and transformation in vadose and aquifer groundwater, and constructed an integral risk-based framework to help to calculate the buffering distance in shallow aquifers against the leachate contamination. Based on the framework and method, a case study is carried out. The results indicate that Zn and Ni have experience a similar dilution and attention process, but due to its smaller RDAF (required dilution and attenuation factor, equal to the ratio of initial concentration to limit concentration) value, Ni needs only a vertical separation distance (VSD) of 4 m (a 4 m vadose zone with saturated conductivity of 1 × 10-5 cm/s) without additional requirement on horizontal buffering distance. While, Zn requires an additional buffering distance of 380 m in addition to the VSD to achieve to be diluted/attenuated to a risk-acceptable level. 2,4-D has larger RDAF than Zn, but due to its difference in degradation characteristics from Zn, it also needs a smaller buffering distance (135 m) than Zn; Further studies shown that the sensitivity of the dilution and attenuation of heavy metals to distance is relatively weak, especially when the distance is greater than 800 m; organic pollutants are more sensitive to distance, even more than 800 m; for the landfill site to dispose organic pollutants, the buffering distance of 400 m is a conservative choice, while for sites to dispose heavy metal wastes, 400 m may be a risky decision and needs further calculation and demonstration. •Buffering distance, if properly set, helpful to prevent drinking well pollution.•Ni need no horizontal buffering distance, for its small requirement on DAF.•It increases to 380 m for Zn, for its required DAF is 2 times smaller than Ni.•2,4-D, though large in required DAF, needs only 135 m for its high degradability.•For impractical larger distance, reduction on initial concentration is an alternative.