While we were at the Columbia Ridge Landfill, Kelly asked us if we wanted a tour of the hazardous waste landfill next door. Who wouldn’t say yes to an invitation to see a hazardous waste landfill? Kelly handed us off to his counterpart, Dave, manager of the Chemical Waste Management of the Northwest’s Arlington Facility, referred to casually as Chem Waste.
It had never occurred to me to wonder what went on at a hazardous waste facility that was different from a normal waste disposal facility. I guess I figured they just buried it in holes that had thicker linings.
Dave took us in by the main gate where he radioed the office to have the gate opened. Like most waste disposal facilities, the first thing we passed were the scales. Past them was the laboratory. In these four or five mobile home-like buildings a sample of every load that comes to the facility is examined. The lab looks at it to see if it is within Resource Conservation and Recovery Act (RCRA) Subtitle C standards.
Everything that comes in to the facility is supposed to have a manifest describing what it is and how much of it there is. Also, each type of waste that comes to the facility is required to submit a sample for evaluation before the real shipment arrives. This allows the lab to determine whether or not they can treat it.
The lab determines what is needed to stabilize each type of waste. Stabilization means turning liquids to solids and binding some chemicals to others. The primary ingredients Chem Waste uses for stabilization are: cement, fly-ash (from a nearby coal power plant), and a rougher version of the stuff that is the base in foundation make-up.
They have an area where there are four or pits dug in the ground. These pits have a shipping container buried in them, the shipping container doesn’t have a top, but its rim comes up to the level of the ground.
There is an excavator for each pit. The excavator mixes the hazardous waste with the various stabilizing agents until it is considered stable. They scoop it out into dumptrucks that take it to be landfilled.
Dave called this bucket chemistry. He thinks they can control for substances up to 5 ppm, but past that, with the methods they are currently using, is impossible.
For items that are larger than a tennis ball, which are considered debris, Chem Waste cannot use the same process because the contamination on these items will not bind with the stabilizing agents. They have to pack the debris in square HDPE tubs. Officially these black tubs are called vaults. After being loaded they are covered with a thinner HDPE lid and are buried in layers.
The soils that have been stabilized are buried in landfill cells. The vaults and drums are also buried. There are several other processes that are used at Chem Waste to stabilize hazardous waste, but it seems the primary method is the mixing pits shown above.
They also have a leachate collection system here and recycle the leachate, which means whatever they collect is run back through the landfill in what is hoped to be a closed loop cycle.
I was surprised by how hazardous waste is dealt with. I never would have guessed that excavators stirring different materials together in big pits was a part of the process.