Covanta Derwood Transfer Station

There is a lot of waste generated in the USA. In 2018, there were 292 million tons of waste generated. Averagely that is 4.9 Lb. of waste per person. The waste from municipalities is recycled the most. The data says that in 2018, there was a recycling rate of 32%. Some of the waste is reprocessed not other means such as bio-chemical management.The largest categories of waste pertain to paper, food plastics, yard trims, and metals. Food, plastics, and paper make are the main resources for energy production from waste.

A landfill has very detailed business operations. The waste arrives at the facility in garbage trucks on a section called the Cell. The cell is made of an isolated layer, that prevents any waste or liquids from leaking. In the cell, the waste is sorted out. This unit is enclosed, as the sun and the atmospheric conditions can interact with the waste. Afterward, the garbage is compressed in the smallest volume possible. The cell will accept new waste until it is full. When it reaches, it is further reinforced on top with various materials and dirt. The idea is that the area on top of the cell is reused and to support vegetation.

The important part of this process is the base of the cell. It must prevent liquids and other pollutants from reaching the soil. For this reason, the cell is isolated below with layers of plastic and clay, to create a strong isolation system.

Regarding liquids, they are collected onto a unit called the sump. In this unit, the liquids are processed, and when they are cleaned on pollutants, they are reintroduced onto the environment. Each landfill has groundwater monitoring, which means they collect the quality of groundwater before it reaches the landfill and afterward it exits the landfill. Regarding gasses generated by the waste, they are collected via a special system that ends up reusing the methane generated and the gases to produce energy.

When a landfill reaches the point that all the cells are full, then the landfill stops operations. This doesn’t mean that the owners of the landfill have no responsibilities. They must be monitored for 30 years after closure, and that means assuring the quality of groundwater and preventing leakage to the soil of any type of waste.

When waste arrives in a landfill it needs to be sorted out first. Therefore, we have waste sorting stations. These are specialized for municipal waste and not for other types of landfills. Garbage trucks dump their municipal waste. Then the waste is separated into recyclable waste and non-recyclable materials. The non-recyclable garbage is then separated into hazardous waste, energy recyclable waste, landfill waste, or incinerator waste. Afterward that it has been sorted out, it is then loaded onto garbage trucks, and this deposits the waste onto their designated places.

There is an interesting type of landfill, inert landfills. This type of landfill receives sand, concrete, and other waste related to construction. This type of waste does not have any biohazards nor decomposes, or it does so very slowly. These types of waste neither produce liquid waste. In this category, we mostly have asphalt, rocks, bricks, yard leaves. In this category, we do not include demolition waste.

Sanitary landfills offer a more advanced waste management approach that further reduces the chances of environmental contamination. The basic unit of a sanitary landfill is still the cell. The idea is to create soil tranches. The garbage is deposited onto layers 1 to 3 meters high and then compacted by bulldozers to reduce the volume. Then the garbage is covered by a layer of dirt. Multiple of these layers are piled together until they reach maximum capacity and thus, we form a cell. The cell is then reinforced on all sides to prevent leakage to the soil.