Guam's new Layon Landfill has been carefully crafted -- unlike its predecessor, the Ordot dump -- to protect human health and the environment.
That means no more polluted water dripping into the rivers, no more spontaneous fires that burn for days, no more hordes of flies that blacken the sky and any surface they land on.
The Ordot dump, which was shut down on Aug. 31, was first found in violation of the Clean Water Act in 1986. In 2004 the District Court of Guam issued a consent order to close the foul dump and open a new landfill. But by 2008, no progress had been made, so the court appointed a federal receiver to oversee the closure of the dump and the building of a new landfill. Layon opened on Sept. 1 much to the relief of Ordot residents.
So how does the landfill work?
Paul Baron of Winzler & Kelly, an engineering firm that provides construction management services for the landfill, and Chris Lund of Gershman, Brickner & Bratton, the federal receiver, filled us in.
First, a landfill is very different from a dump. A landfill, the experts emphasized, has controls that mitigate the garbage's impact on the environment and community. A dump is basically just an area where people pile up trash. The Layon Landfill's environmental controls exceed both Guam and federal requirements for environmental protection, according to federal receiver Gershman, Brickner & Bratton.
To understand how the landfill works, perhaps it's best to start at the beginning: the waste bins outside of houses, apartments and commercial buildings. This trash is collected and hauled to a transfer station, where trash is stored until it is brought to the landfill. There, waste is preliminarily scanned for radiation -- something that might be found in medical waste -- and then loaded up in a huge semi-trailer truck to be carried to Layon, Baron said.
Layon Landfill is deep in Inarajan, where the fenced-in facility sticks out against the wild and mountainous backdrop. The truck coming from the transfer station can carry up to 29 tons of trash, so only about 10 truckloads have to be filled for a day's trash. The truck rumbles down the newly paved road leading to the landfill and, upon entrance, is weighed and undergoes one more radiation check before being allowed to go to the unloading spot. If radiation is found, the truck is sent back to the transfer station where the waste is inspected.
The truck makes its way to the "cells" -- vast, shallow pits where trash will be dumped, compacted, covered with soil, and built up until capacity is reached. Only two cells of 11 have been built, but all together, these cells should hold trash for about 50 years or longer, depending on how much people reduce, reuse and recycle, according to Lund.
The cells, which look like holes cut into the earth, actually extend deeper beneath the ground in a series of carefully engineered layers meant to protect the outside of the landfill from the pollutants inside it.
The cells are covered with a rain cap, a white liner that collects and leads rain water away from trash. The rain cap is peeled away as needed, so trash can be dumped onto the soil beneath it. The 3-foot thick soil is a protective layer for the complex liner system below, that collects leachate, the polluted water that filters through the trash and into the ground, said the experts.
The trash comes out of the back of the truck, which has a moving floor that shuffles the waste out. Once in the cell, it is compacted by bulldozers, and covered at the end of the day. A tarp can be used until there is too much trash, in which case soil is dumped over everything.
Rain that falls on the trash seeps through the waste, becoming leachate. The leachate, in turn, seeps through the soil, and hits the primary "leachate collection layer." This layer begins with a thin, 3/4 of an inch thick geocomposite, a soft, fuzzy, carpet-like material that soaks up the polluted water like a sponge and directs it to the next part of the layer, a pipeline. The pipeline pumps the water to a leachate collection tank and then straight to the Inarajan Waste Water Treatment Plant, experts said.
Under the geocomposite is the "moisture-barrier layer." It's composed of a hard, rough, geomembrane, a tough plastic that is less than half an inch thick. This layer shouldn't allow much liquid through.
Right below this is a secondary leachate-collection layer and moisture-barrier layer, which does the exact same thing -- back up against the top layers.
Then there is one more protection -- 3 feet of low permeability soil. By now, no leachate should have gotten through. In many landfills there is only the primary leachate collection layer and moisture-barrier layer, coupled with the low permeability soil. Layon's secondary
leachate collection and moisture-barrier layers puts the landfill a step above others.
Underneath it all is a subdrain that collects clean groundwater, and keeps it away from the cells. This subdrain takes water that may be pushing up toward the landfill and pipes it to a collection tank. The water is tested before being discharged back into nature, experts said.
Leachate isn't the only pollution the trash creates. There's also gas, which is formed as substances interact and decay. Gas pipes will be added in the waste collection area as waste accumulates. The landfill gas may be burned off, or used as a fuel source, depending on the quality and quantity of the gas that is generated.
That's how the first two cells work -- future cells that are built may vary, depending on changing regulations or improved technology.
Eventually the cells will build up so that they form a small hill that rises more than 100 feet above ground. Then they will be capped, or permanently closed, and put into a 30-year, post-closure care program that will make sure the site is maintained properly, said Lund.
While the Layon Landfill is an improvement over the Ordot dump, it is, essentially, a temporary solution. Once the landfill is full, another will have to be built. Officials stressed the importance of waste reduction measures, such as recycling, to lengthen the landfill's life-span.
No comments:
Post a Comment