Oberflächenabdichtungen aus PE‐HD‐Dichtungsbahnen für Altdeponien

Surface lining with HDPE geomembranes of old municipal waste landfills. Until mid‐2005 approximately 250 old municipal waste landfills have to be closed, because they failed to meet the requirements according to the state of landfill engineering. After closure, a containment and remediation concept has to be put into action. At landfill sites with appropriate conditions (e.g. base liner and waste water collection system), one may try to stabilize the waste body by forcing up through water infiltration the anaerobic biochemical reaction within the waste body or by aerobic stabilization techniques. However, engineered capping systems are an indispensable tool in the containment strategy for waste disposal. Reliable, highly effective and long lasting liner systems can be installed even under the special conditions on the surface of old landfills. In particular, selected HDPE geomembranes are highly suited for these conditions. However, approval of geomembrane products for this application is essential, since geomembranes made of different HDPE resins as well as differently produced out of the same HDPE resin may extremely differ in their long‐term and installation properties.     

Subsidence performance of landfills

This paper presents field measurements of landfill subsidence for five municipal solid waste landfills. Data from the.five sites are within the range of landfill subsidence reported in other publications.

At one site with variable subsidence of up to 10 percent of the landfill height in 3 years after capping, portions of an in-situ HDPE cap geomembrane were uncovered. The geomembrane showed no visual signs of subsidence-induced distress.     

Preliminary results of composite liner field performance study

This paper presents preliminary results of a study of the field performance of composite liners. The purpose of the study is to evaluate the ability of composite liners to contain municipal solid waste (MSW) leachate. The paper presents data for double-lined MSW landfills having composite top liners consisting of a geomembrane (GMB) upper component and a compacted clay liner (CCL) lower component. Data on flow volumes and flow constituents for the leachate collection and removal system (LCRS) and the leakage detection system (LDS) components of the double liner system are analyzed to assess whether leakage has occurred through the composite top liner. Data for nine MSW landfill cells with monitoring periods of up to eight years are presented. Preliminary results indicate that the nine composite liners are performing well and are effective in containing MSW leachate.     

Contaminant mitigating performance of Chinese standard municipal solid waste landfill liner systems

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.     

Numerical study of strain development in high-density polyethylene geomembrane liner system in landfills using a new constitutive model for municipal solid waste

Tensile strain development in high-density polyethylene (HDPE) geomembrane (GMB) liner systems in landfills was numerically investigated. A new constitutive model for municipal solid waste (MSW) that incorporates both mechanical creep and biodegradation was employed in the analyses. The MSW constitutive model is a Cam-Clay type of plasticity model and was implemented in the finite difference computer program FLAC?. The influence of the friction angle of the liner system interfaces, the biodegradation of MSW, and the MSW filling rate on tensile strains were investigated. Several design alternatives to reduce the maximum tensile strain under both short- and long-term waste settlement were evaluated. Results of the analyses indicate that landfill geometry, interface friction angles, and short- and long-term waste settlement are key factors in the development of tensile strains. The results show that long-term waste settlement can induce additional tensile strains after waste placement is complete. Using a HDPE GMB with a friction angle on its upper interface that is lower than the friction angle on the underlying interface, increasing the number of benches, and reducing the slope inclination are shown to mitigate the maximum tensile strain caused by waste placement and waste settlement.     

HDPE土工膜端部张拉力的大规模实测数据分析

 垃圾填埋场边土工膜主要受到温度应力和垃圾压缩引起的张拉力的作用，为评价垃圾填埋场防渗系统中高密度聚乙烯(HDPE)土工膜的温度应力和垃圾填埋压缩引起的端部张拉力，以短纤维无纺布、HDPE土工膜组成防渗系统，进行大规模现场试验。试验结果表明：伴随环境温度的下降，HDPE土工膜中产生温度应力，当填埋高度较小时作用在HDPE土工膜端部的张拉力主要为温度应力；随着填埋高度的增加，压缩引起的HDPE土工膜端部张拉力增大。用有限元算法对压缩引起的端部张拉力进行分析，并采用温度与HDPE土工膜张拉力的关系对温度应力进行分析。计算结果与实测结果的对比情况表明，考虑填埋压缩引起的张拉力的应力松弛后计算结果更加接近实测结果。     

Tension in geomembranes on landfill slopes under static and earthquake loading—Centrifuge study

Geomembranes are some of the most commonly used geosynthetics in landfill liner systems. Geomembranes may experience harsh environmental conditions such as extreme temperatures or earthquake loading. Earthquake loading can be an extreme loading case for landfills located in seismic regions. This study, based on dynamic centrifuge testing, investigates the effects of simulated earthquake loading on the tension experienced by the geomembrane on a landfill slope. The landfill modelled in the dynamic centrifuge tests was a 7 m high municipal solid waste (MSW) landfill with a single geomembrane-clay liner system (45° side slope and 10 m slope length). Results show that moderate earthquake loading (base acceleration between 0.1 and 0.3 g) can result in a permanent increase in geomembrane tension of 5–25%.     

云南省新平县生活垃圾卫生填埋场工程设计

介绍了云南新平县城市生活垃圾卫生填埋场工程概况及主要设计内容。在设计中针对当地气候条件和地质特征,因地制宜,优化设计,旨在提高工程经济性及实用性。其中填埋工艺采用了"HDPE+GCL"水平单层复合防渗系统,渗滤液采用了过滤预处理+两级碟管反渗透(DTRO)组合处理工艺。     

The effects of reduction of the deposited waste on short‐term landfill leachate composition of a landfill: a case study in Norway

Municipal solid waste landfill leachate was sampled over from a landfill receiving varying amounts of municipal solid waste. The investigation aimed to provide information on expected leachate changes in the short term, either after closure of an active landfill, or after a strong decline in the amount of waste deposited at smaller landfills. It was found that during a two year period following a sudden decline in the amount of waste deposited, the levels of various chemical and physical parameters all dropped sharply. The reasons for the decline in discharge levels are thought to be aerobic decomposition taking place in the municipal solid waste just after landfilling, and thus the decline in the impact of this process when there were less fresh waste masses available, and formation of preferential flow paths for the leachate as the municipal solid waste stabilized in the landfill.     

垃圾填埋场防渗衬垫特性的离心模型试验与数值分析研究

垃圾填埋场中垃圾体和防渗土工膜的受力变形特性是普遍关心的问题,在现场试验尚无法获得满意的监测结果时,利用离心模型试验和有限元数值分析进行探讨性研究也是可以尝试的途径。通过离心模型试验研究和有限元计算,模拟了垃圾填埋场中填埋垃圾大变形条件下土工防渗膜的变形性状,在模型比率80的条件下,可以找到相应的模型材料来模拟实际工程中的土工膜;选用的防渗膜模拟材料和木屑土能较好地模拟垃圾填埋场中材料;邓肯-张模型和Goodman接触面模型能模拟垃圾土和土工膜以及界面的工作状态;土工膜中最大拉应力靠近坡肩,可达到极限抗拉强度的1/1.5倍;考虑到HDPE膜的抗拉安全,最大设计坡长应加以控制。     

Performance issues of barrier systems for landfills: A review

The objective of the paper is to give an update in key topics related to performance issues of barrier systems for landfills. The objective of using barrier systems is to minimize the impact of contaminants on the surrounding environment. To achieve this goal puncture protection of the geomembrane must be ensured. An update is first given with respect to this matter. The question of the stability on slope of geosynthetic barrier systems is then discussed and an insight is given in modeling and laboratory measurement of parameters required to perform reliable modeling, especially as regards the case of piggy-back landfills. Geotechnical centrifuge modelling tests are very important for simulation of landfill stability induced by the failure of geosynthetic interfaces and validation of complicated numerical models, especially for the high food waste content landfills. The seismic design or assessment of landfill stability with respect to geosyntheics needs to be investigated. Finally, the question of transfers through bottom barrier systems is addressed, giving an update especially in the analytical solutions developed in the past 10 years in China in this matter. The breakthrough time based design method for landfill liner system was then summarized. The behaviour of double-liner system and its simplified performance-based design method should be further investigated in the high food waste landfills with high leachate level.     

我国城市垃圾渗滤液处理的技术及现状

在简要介绍我国城市垃圾处理的发展历史与现状后，针对国内应用最为广泛的城市垃圾卫生填埋场所产生的垃圾渗滤液处理技术进行了大量的调查、类比工作，并结合国内的多个工程实例总结出我国目前垃圾渗滤液处理的现状．     

山谷型生活垃圾填埋场库区雨污分流设计

以甘肃省肃南县城区生活垃圾填埋场为例,对山谷型生活垃圾填埋场库区的雨污分流措施进行了探讨,提出了一种填埋场雨污分流设计方案,以实现渗滤液的减量化,为山谷型生活垃圾填埋场工程的雨污分流设计提供了借鉴。     

基于风险降低的导电HDPE土工膜在防渗系统中应用

在对传统使用的HDPE土工膜防渗系统渗漏原因和风险进行分析的基础上,推荐了导电HDPE土工膜作为防渗系统中的升级新型材料;通过对导电HDPE土工膜优点及其应用情况的分析,凸显了导电HDPE土工膜在防渗系统中可以检测渗漏和降低风险的重要地位。     

Quality assurance of geomembranes used as linings for hazardous waste containment

The lining of a facility for storing or disposing of hazardous materials or wastes on land must serve as an effective barrier to prevent potential contaminating species from migrating into the ground and the groundwater. The process from the design phase through the manufacture of a polymeric geomembrane to its installation and acceptance as a liner involves many steps that must be controlled in order to assure the ultimate effectiveness of the lining.

In this paper, a program of quality assurance and quality control involved in the critical steps in the process of constructing a lined waste disposal facility from its design through the final acceptance is described. Included are design, geomembrane selection and compatibility testing, specification, raw materials, geomembrane manufacture, panel fabrication, shipment to field site, inspection, installation and performance testing of the lined facility. Emphasis is placed on factors and properties of geomembranes that relate to service performance and must be controlled. The properties include overall thickness, thickness of coatings above threads, composition control, crystallinity, carbon black content, ply adhesion and seam integrity and strength.     

MBR/DTRO/沸石生物滤池用于垃圾渗滤液处理工程

青岛市小涧西垃圾综合处理厂渗滤液处理扩容改造工程的设计规模为900 m3/d,渗滤液处理采用MBR/DTRO/曝气沸石生物滤池工艺。介绍了工程的设计情况,着重阐述了MBR系统、DTRO系统和曝气沸石生物滤池系统的设计参数、工艺流程及设计特点,为该工艺在垃圾渗滤液处理工程的应用提供参考。     

Magnitude and significance of tensile strains in geomembrane landfill liners

The implications of the tensile stress/strain developed in high density polyethylene (HDPE) geomembranes (GMB) is explored in the context of a reduction in stress crack resistance due to ageing in contact with leachate in a municipal solid waste (MSW) landfill. The experimental evidence of GMB cracking and ultimately failure when subject to excessive tensile strains is discussed to highlight the need to limit the maximum tensile strain sustained by an HDPE GMB to an acceptable level if good long-term performance is to be ensured. The effect of both local GMB indentations induced by gravel in an overlying drainage layer or an underlying clay liner on tensile strain is reviewed. In addition, the tensile strains caused by down-drag in the GMB on side slopes with settlement of the waste is examined. The key research related to tensile strains developed in GMBs from these sources is reviewed and new data presented. It is shown that an appropriate protection layer over the GMB can limit local GMB tensile strains to less than 3% and that the selection of a suitable slope inclination and stiffness of a geotextile reinforcement layer can limit the GMB strains due to down-drag to less than 2% and geotextile strains to less than 4% after long-term waste settlement.     

Ageing of HDPE geomembrane exposed to air,water and leachate at different temperatures

The latest findings regarding the long-term performance and service life of HDPE geomembrane (GM) samples exposed to air, water and leachate are presented based on data from samples that have been ageing for 8–10 years. Some of the GM samples are in Stage II, some in Stage III and some have completed all three stages of the service life. The paper provides: (1) improved data on antioxidant depletion rates for GMs immersed in air, water and leachate; (2) estimates of antioxidant depletion time (Stage I) at typical liner temperatures in air, water and leachate and, based on this data, an estimate for a composite liner at typical liner temperatures; (3) data regarding the changes in the physical and mechanical properties of the GM samples with time; (4) a surface analysis of virgin and aged GMs; (5) an initial estimate of the induction time (Stage II) and polymer degradation time (Stage III) and service lives of GM in laboratory immersion tests; and (6) predictions of the service life of leachate immersed GM at typical landfill temperatures. Based on these predictions, it appears likely that the service life of the specific GM tested immersed in leachate is likely to exceed 700 years and will probably be of the order of 1000 years (or longer) at 20 °C, more than 150 years and likely 225–375 years at 35 °C and more than 40 years and likely 50–90 years at 50 °C. The service life in a liner configuration may be expected to be longer than predicted here for immersion in leachate.     

某填埋场垃圾堆体边坡失稳过程监测与反分析

某填埋场是国内首批在场底铺设复合衬垫系统的大型卫生填埋场,该场垃圾坝前堆体边坡于2008年6月连续强降雨期间发生失稳事件。介绍该堆体边坡失稳过程的现场监测结果,包括坡面水平位移、深层侧向位移和渗滤液水位。基于监测数据,开展堆体边坡稳定性反分析工作,探讨复合衬垫系统界面抗剪强度取值方法,提出抽排竖井迫降水位、铺膜防渗等应急抢险措施。现场监测和理论分析结果表明:堆体边坡中高渗滤液水位是导致其失稳的关键因素,堆体边坡水平位移速率和渗滤液水位高度呈明显正相关关系;该堆体边坡失稳模式是沿场底复合衬垫系统中软弱界面的深层滑移;斜坡场底上复合衬垫系统在滑移过程中发生位移-软化效应,其界面强度介于峰值强度和残余强度之间;抽排竖井迫降水位是最直接、有效的应急抢险措施。     

垃圾填埋场土工合成材料界面摩擦特性的拉拔试验研究

土工合成材料与填料的界面特性是决定垃圾填埋场中衬垫系统与土工合成材料受力特性的重要因素。选择3种不同种类的土工合成材料,用砂土和黏土为填料,通过拉拔试验研究土工合成材料的界面特性。试验结果表明:界面的峰值剪切强度与峰值位移随着法向应力的增加而增加;土工合成材料与黏土之间的摩擦角较大;填料为砂土时,无纺布与填料间的摩擦角最大,EPDM次之,HDPE最小;当HDPE上下都铺无纺布时,界面的摩擦系数最小。