Landfill Pollution Risk Assessment In Beijing-China

This thesis addresses the assessment of the pollution risk of municipal solidwaste disposal sites in Beijing especially in the suburban districts of Shijingshan,Haidian, Chaoyang, Fengtai, and Daxing County, focusing on areas within thesixth ring road.The study found that due to lack of proper regulations on disposal of solid wastes,rampant disposal was common especially in the suburban areas. Landfillpollution risk assessment has become an important tool in addressing problemsemerging from unregulated disposal of solid waste in the environment. In thisstudy a two-tiered approach was used. Tier1is mainly risk screening and rankingof the sites based on their level of risks;while Tier 2 is more site-specifictargeting only the site which had the highest level of average risk. Preliminaryassessment identified 57 candidate sites for risk assessment.The results showed that over 90% of the sites were located in areas of highgroundwater vulnerability, where the aquifer system is single layer aquifer. Thevadose zone and aquifer has low natural attenuation because it contains mainlysandy-gravel and clay or organic content is low. The pollution risk togroundwater was found to be highest especially to the west of Beijing ? InFengtai and Shijingshan and parts of Haidian districts the aquifer system isunconfined aquifer and water table is less than 10m from ground surface in someplaces unlike in Daxing and Chaoyang districts which have mostly multi-layeraquifers systems and water table is low. The upper plain is transition zones fromsingle aquifer to multilayer aquifers and so the geological formation may allowinteraction of the aquifers meaning even deep aquifers may be contaminatedthrough hydraulic connection of the aquifers in this zone. Along Yongding River,there is extensive sedimentary deposition from the river and most of the siteswere former sand, gravel and soil mining pits which were readily available andwere used without further engineering preparation to minimize leachate, andLFG escape from the site. Numerically simulated remediation shows highprospects of using source control methods in conjunction with other remediationsuch as bioremediation.