Technical note Contaminant mitigating performance of Chinese standard municipal solid waste landﬁll liner systems Y.-J. Du a, * , S.-L. Shen b , S.-Y. Liu a , S. Hayashi c a Institute of Geotechnical Engineering, Southeast University, Si Pai Lou #2, Nanjing 210096, China b School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai 200030, China c Institute of Lowland Technology, Saga University, Honjo 840-8502, Japan article info Article history: Received 15 December 2007 Received in revised form 12 November 2008 Accepted 14 November 2008 Available online 20 January 2009 Keywords: Compacted clay liner Geomembrane Landﬁll Municipal solid waste Performance abstract In 2004, Chinese Government prescribed standard municipal solid waste (MSW) landﬁll bottom liners. However, very limited research has been conducted to evaluate the performance of the standard MSW landﬁll bottom liners prescribed by the Chinese Government. In this paper, the performance of the two types of Chinese MSW landﬁll bottom liner systems was evaluated based on: (1) the maximum leachate head; (2) leakage rate; (3) peak concentration of the target contaminant in an aquifer which was underlain the assumed landﬁll, and (4) total mass per unit area of the target contaminant discharged into the aquifer. The performance of the German standard MSW landﬁll bottom liner system was evaluated and compared with that of Chinese ones. It is found that the calculated maximum leachate head for the Chinese landﬁll liner systems was much higher than that for the German one. The calculated leakage rate, peak concentration and the maximum total mass per unit area in the aquifer of the target contaminant show that the performance of the Chinese standard landﬁll liner Type 2 is practically the same as that of the German standard landﬁll liner with holed geomembrane wrinkles, while the Chinese standard liner Type 1 is less effective, with regarding the mitigation of the impact of landﬁlls to the groundwater quality. It is concluded that the overall performance of the Chinese standard landﬁll liner systems is less strict than that of the German standard landﬁll liner system. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction Recently in China, the amount of municipal solid waste (MSW) is increasing at about 10% annually and the averagely annual amount is about 190 million tonnes (World Bank Report, 2005). Among these wastes, 70% is disposed to landﬁlls, 20% is composted and 10% is incinerated. Among landﬁlls, about 80% is open-dump without any strict construction of bottom liner systems, which has caused serious environmental pollution, especially the pollution of the ground water by the organic contaminants contained in the solid wastes (World Bank Report, 2005). In an attempt to solve this problem, Chinese Government prescribed standard MSW landﬁll bottom liners (CNMC, 2004). However, very limited research has been conducted to evaluate the performance of the prescribed Chinese MSW landﬁll bottom liners. As a result, a question arises that whether the Chinese MSW landﬁll bottom liners can mitigate the landﬁll impacts to surroundings as effective as most strictly prescribed landﬁll bottom liners such as German type. The objective of this study is to evaluate the performance of the Chinese standard MSW landﬁll liner systems in terms of mitigation of landﬁll impacts to groundwater quality. The shortcomings of the Chinese standard landﬁll liner systems against the Germany stan- dard landﬁll liner system are discussed. The performance of the three standard landﬁll liner systems is evaluated based on the maximum leachate head, leakage rate, peak concentration, and the maximum total mass per unit area of the target contaminant in the aquifer. 2. Chinese standard MSW landﬁll liner systems Fig. 1 shows the minimum design requirement of two types of Chinese standard MSW landﬁll liner (hereafter labeled as CN liner) system. In Type 1 (hereafter labeled as CN Type 1), a natural clay deposit with a thickness larger than 2 m and a hydraulic conduc- tivity less than 10 9 m/s are used as a containment barrier. In Type 2 (hereafter labeled as CN Type 2), a composite liner system is used. The thicknesses of the high-density polyethylene (HDPE) geo- membrane liner (GM) and compacted clay liner (CCL) are greater than 1.5 mm and 1 m, respectively. The hydraulic conductivity of CCL is less than 10 9 m/s. The German standard MSW landﬁll bottom liner (hereafter labeled as DE liner) system is illustrated in Fig. 1 (Manassero, 1997; EEA, 2000). Generally, as compared with * Corresponding author. Tel./fax: þ86 25 83795086. E-mail address: yanjundu@gmail.com (Y.-J. Du). Contents lists available at ScienceDirect Geotextiles and Geomembranes journal homepage: www.elsevier.com/locate/geotexmem 0266-1144/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.geotexmem.2008.11.007 Geotextiles and Geomembranes 27 (2009) 232–239