Environmental Engineering Reference
In-Depth Information
16.2. Types of lining systems and definition of basic components
Modern MSW facilities are typically designed with barrier systems that include
sidewall liners, bottom liners and capping or cover liners (see Figures 16.3 and
16.4). The main components of the bottom lining systems are the drainage layers or
leachate collection and removal system, the manmade barrier and the attenuation
layer or geological barrier. Apart from the geological barrier (also shown in Figure
16.4), which can only be of natural type, the other layers can be composed of natural
or amended soils and/or geosynthetics and related products.
Cover liners
Waste
Side wall liners
leachate
Basal liners
Water table
Figure 16.3.
Confinement barriers in municipal solid waste landfills
The most relevant advancements in manmade barriers in the past few years are
related to the use of geosynthetic clay liners (GCLs), the modeling of lining system
performance (performance design) and the estimation of related parameters via
laboratory and field tests and data from monitoring systems.
Lining systems for steep to very steep slopes are also receiving a lot of attention
stemming from the fact that landfills are increasingly being designed to
accommodate two factors: land saving and increase in landfill capacity. There is also
the fact that old quarries, especially those formerly used to mine sand and gravel, are
still favorite spots for landfills, even though these are usually important sources of
groundwater recharge. The use of GCLs, slurry walls and compacted clay liners
reinforced by the use of mixed cement [MAN 93] and geocomposites [HOH 95] in
order to avoid stability problems, seems to have become very popular [BOU 02]. On
the other hand, the drainage and filter layers are not usually a problem for steep
slopes, whereas the protection layer can be very important, particularly when
geomembranes and GCLs are employed. In some cases it can be a good practice to
use certain types of wastes as a protection layer, such as tires and big sacks
containing waste in a powder form.
