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In the past we have covered the subject of surface impoundments in some detail. From design and operation to inspection and response actions, we have taken a close look at what that type of land disposal unit is used for and how one must be managed. Today we are going to take a similar look into hazardous waste piles.

The regulations concerning waste piles can be found in Part 264/265, Subpart L of 40CFR. Basically, a waste pile is a pile of noncontainerized solid, non-flowing hazardous waste. Waste piles are not a disposal method but merely serve as a storage and/or treatment option for generators. Because they are not an end-of-life stage for waste, Subpart L does not contain post-closure care regulations. However, waste piles do sometimes need to close with waste still in place. If this happens, the waste pile is closed as a landfill and is susceptible to all applicable regulations. This is discussed in more detail below.

According to the EPA, “owners and operators of permitted waste piles that meet special requirements are subject to reduced regulation. Specifically, the waste pile must be located inside or under a structure and not receive free liquid, protected from surface water run-on, designed and operated to control dispersal of waste, and managed to prevent the generation of leachate. If these standards are met, the owner and operator of the permitted waste pile are exempt from groundwater monitoring requirements, as well as the design and operation requirements for waste piles.”

How are waste piles designed?

The minimum technological requirements (MTRs) for waste piles are just about the same as those of surface impoundments. These requirements include the need for new units, lateral expansions, and replacement units to be equipped with a double liner and leachate collection and removal system (LCRS).  Additionally, waste piles, with some exceptions, require a second leachate collection and removal system above the top liner.

A permitted waste pile that is not subject to MTR (things like units, lateral expansions, or replacements that were commenced before July 29, 1992) only needs to have one liner and meet basic LCRS requirements. The EPA states, “interim status waste piles that are not subject to MTR are subject only to liner, run-on, and run-off controls if leachate or runoff is found to be a hazardous waste.”

How do you close a waste pile?

As mentioned earlier, a waste pile is a storage or treatment area as opposed to an end stage disposal option for hazardous waste. Because of this, prior to closure all waste residues and contaminated subsoils and equipment must be removed or decontaminated at closure. According to the EPA, “if an owner or operator removes or decontaminates all waste residues and makes all reasonable efforts to remove or decontaminate all structures and soils and finds that some contamination remains, the waste pile will then be subject to the closure requirements for landfills, including post closure care.”

Are there special requirements for different kinds of wastes?

As with many storage options, RCRA puts special requirements on storing ignitable or reactive wastes in waste piles because these types of materials “require continuous protection from conditions that could cause them to ignite or react.” Similarly, there are regulations prohibiting the placement of incompatible wastes or materials in the same waste pile unless certain precautions are taken to avoid incident. Lastly, if an owner/operator plans to manage dioxin-containing waste he or she must have a special management plan approved by the Regional Administrator or authorized state.

What’s the difference between a waste pile and a containment building?

According to the EPA, “containment buildings, sometimes characterized as ‘indoor waste piles,’ are units used to hold noncontainerized piles of hazardous waste. The difference between waste piles and containment buildings, from a regulatory standpoint, is that containment buildings are not land disposal units. For this reason, containment buildings are designed with a container system rather than a liner and leak detection system.”

Quoted and EPA cited information (unless otherwise noted) for this blog post was gathered from the EPA document, “Introduction to Land Disposal Units.” As always, this blog post is not intended to be comprehensive and it is always best to check with the EPA and local government for full, up-to-date, rules and regulations.

You know the phrase “you learn something new every day?” I sometimes wonder about that. I saw a card once that reflected my feelings pretty perfectly. It said something like, “I disagree with the idea that you learn something new every day. I think there are some days when I learn nothing at all, and in fact, forget some things.” But I am happy to say that today was one of those days when I did learn something!

Now for some of you this will probably not be new news but hopefully I will still provide you with some helpful information about what I learned. So, to alleviate the suspense (assuming you didn’t guess from the title of this post) I learned today that there is a difference between “empty” and “RCRA empty.”

Now I realize that regular hazardous waste generators may be thinking to themselves, “Yeah, we knew this…” But I found it pretty interesting and decided to look into it a little more. Generally, we think of something as empty when it appears empty to the naked eye. However, hazardous containers that are defined as ‘RCRA empty’ are not subject to EPA regulation even when residue remains.

So what makes a container RCRA empty? I learned that there are two general (common) answers as well as a third less common condition. To begin, we will determine if the waste was acutely hazardous.

What is an acutely hazardous waste?

An acutely hazardous waste is one that is P listed or designated with the sub-code H. In layman’s terms, acute hazardous waste is waste that is considered to present a substantial hazard whether managed properly or not. If your waste is acutely hazardous, there are a few ways you can make the container RCRA empty.

How do I make a container holding acutely hazardous waste RCRA empty?

The first way is applicable if your container has an inner liner. If it does you just need to remove it and you’re good to go (in terms of your container being empty, you still need to properly dispose of the liner). If your container doesn’t have a liner you need to triple rinse the container with an appropriate solvent. If triple rinsing is inappropriate you must check with the EPA and local government to determine an alternate method.

What if the waste is not acutely hazardous?

If the waste in your container is not acutely hazardous you can use practices that are commonly employed, industry-wide, to empty them to EPA regulated levels. Common methods for emptying are pouring, pumping, and draining. When emptying there are a few rules that constitute “empty.” Firstly, there can be no more than 1” remaining, no more than 3″ waste for small containers and no more than .3″ for large containers.

What is the third condition?

The third condition refers to gas cylinders. Containers holding compressed gasses are considered empty when the pressure in the container approaches atmospheric pressure.

What happens to residues in a container?

Residues which are removed from a container (like liners) are fully subject to RCRA and may or may not be considered hazardous based on waste determination. Residues in the container, however, are considered exempt and are non-regulated.

And as always, this information may not be all-inclusive and it is always best to check 40 CFR and your state regulations for the most up-to-date information.