How Are Land Treatment Units Designed?

According to the EPA, “owners and operators of land treatment units (LTUs) must devise a program and demonstrate its effectiveness given the design of the unit and characteristics of the area. In addition, the regulations require specific operating requirements to be met in the treatment program. The requirements outlined for the treatment program, including design and operating criteria and unsaturated zone monitoring, stem from a treatment demonstration.”

The purpose of the treatment demonstration is for the owner/operator to adequately display the effectiveness of the land treatment unit at degrading or immobilizing the hazardous constituents in the waste placed there within. A treatment demonstration can involve laboratory testing and/or field testing on a sample soil plot.

What is a Treatment Demonstration? 

The EPA states that, “the Regional Administrator or authorized state uses information provided by the treatment demonstration to set permit standards. Interim status units are not required to establish a treatment program because the interim status regulations are self-implementing.” In order for owners and operators to place waste in an LTU the waste must be rendered nonhazardous or less hazardous from placement. The EPA has established a list of parameters that owners and operators must establish during the treatment demonstration. These parameters include the following:

  • “Specify the wastes that may be handled at the unit. In general, land treatment is confined to wastes that are primarily organic and that can be greatly reduced in volume by physical, chemical, and biological decomposition in surface soils. The owner and operator must be able to account for smaller fractions of heavy metals and persistent organic compounds by immobilizing those constituents…
  • Formulate a set of operating measures. The LTU must be operated in a manner that will maximize degradation, transformation, and immobilization of hazardous waste constituents….
  • Establish unsaturated zone monitoring. The purpose of this program is to make sure that treatment is occurring within the treatment zone and that all hazardous constituents are being adequately treated. The information provided from the monitoring can help the owner and operator “fine tune” the treatment process to maximize the success of the treatment. Unsaturated zone monitoring involves soil monitoring (e.g., obtaining soil samples) immediately below the treatment zone…
  • Define the treatment zone. This zone comprises the horizontal and vertical dimensions of the unsaturated zone in which the owner and operator intend to perform the actual treatment. The zone can be no deeper than 1.5 meters (5 feet) and the bottom of the zone must be at least one meter (3.2 feet) above the seasonal high water table.”

According to 40 CFR §264.273, “the owner or operator must design, construct, operate, and maintain the unit to maximize the degradation, transformation, and immobilization of hazardous constituents in the treatment zone. The owner or operator must design, construct, operate, and maintain the unit in accord with all design and operating conditions that were used in the treatment demonstration…

At a minimum the Regional Administrator will specify the following in the facility permit:

  • The rate and method of waste application to the treatment zone;
  • Measures to control soil pH;
  • Measures to enhance microbial or chemical reactions (e.g., fertilization, tilling); and
  • Measures to control the moisture content of the treatment zone.”

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.

What is a Land Treatment Unit?

We’ve done several posts in the past about land disposal units (LDUs); covering landfillswaste piles, and surface impoundments in detail. While landfills, waste piles, and surface impoundments, and land treatment units all serve as the “grave” portion of the cradle-to-grave system set forth by the EPA, landfills, waste piles, and surface impoundments all share several regulatory requirements whereas land treatment units are very different in both purpose and management.

What makes LTUs different?

According to the EPA, “land treatment involves the application of waste on the soil surface or the incorporation of waste into the upper layers of the soil in order to degrade, transform, or immobilize hazardous constituents present in hazardous waste.” This differs greatly from landfills, waste piles, and surface impoundments because the primary goal of the aforementioned is to stop waste from migrating to the surface soil.

In an LTU, the waste is treated “within the matrix of the surface soil.” That said, the EPA mandates that any waste in an LTU be placed in the unsaturated zone of the soil. This is the land that lies above the water table (the highest point of groundwater flow). The success of an LTU is dependent upon the operational management of the unit because of this proximity to the groundwater.

Why use an LTU?

The goal of a land treatment unit is to allow the soil microbes and natural sunlight to degrade the hazardous waste. Because of this, the design and operation standards are very different than those that landfills, waste piles, and surface impoundments face. For example, “land treatment units generally do not use impermeable liners to contain wastes. Instead, units rely on the physical, chemical, and biological processes occurring in the topsoil layers. In a sense, these units can be viewed as an open system.”

In LTUs maintaining proper soil PH, carefully managing the rate of waste application, and controlling the surface water runoff are imperative to the unit running smoothly. “Because placement of hazardous waste in a land treatment unit is considered land disposal, land disposal restrictions (LDR) standards must be considered. If the hazardous waste does not meet the applicable treatment standard prior to placement in the land treatment unit, the unit owner or operator must obtain a no-migration variance before applying any hazardous waste to the unit.”

Keep checking our blog for more posts on land treatment units including design and operating procedures, inspection and response, and closure practices.

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.

How are Hazardous Waste Landfill Designed and Managed?

While we’ve covered certain aspects of Land Disposal Restrictions (LDR) in the past, we’ve not yet talked about how landfill cells are designed and managed. For those who may not know, hazardous waste landfills are large areas of land divided into individual cells. Perhaps the most important thing to note is that because hazardous waste landfills are final disposal sites for much of out hazardous wastes, they must continue to be monitored during their whole active life. This includes closure and post-closure monitoring.

How are landfill cells designed?

Much like the minimum technological requirements (MTRs) for waste piles and surface impoundments, hazardous waste landfills must have a double-liner, a leachate collection and removal system (LCRS), a leak detection system, and actual leakage reporting (ALR). Additionally, landfills, like waste piles, must have a second LCRS above the top liner of the cell. Finally, “landfills have to have stormwater run-on and runoff controls to prevent migration of hazardous constituents for at least a 25-year storm and a cover to prevent wind dispersal.”

How are landfills inspected?

Again, the inspection and response plans for hazardous waste landfills are nearly the same as those for surface impoundments. This includes a response action plan in the event of the ALR being exceeded as well as a construction quality assurance (CQA) program. In addition to having these items in place, a generator or owner/operator must perform monitoring and inspections. “As with surface impoundments and waste piles, these requirements ensure that the unit is maintained in good working condition and that any problems are promptly detected.”

How are landfill cells closed?

When a landfill cell is full it must be closed. Since landfill disposal is typically a permanent situation the closure and post-closure regulations are somewhat different than those for other land-based units. The EPA provides the example of the “requirement for a final cover over the landfill that can provide long-term minimization of liquid migration through the closed landfill, promote drainage, accommodate settling, and function with a minimum amount of maintenance.”

Owner/operators must also comply with the post closure requirements in Parts 264/265.117 through 264/265.120 relating to actions like monitoring and maintenance.

Lastly, owner/operators have to “maintain the final cover, leak detection system, and groundwater monitoring system, as well as prevent run-on and runoff from damaging the final cover and protect the surveyed benchmarks (i.e., location and characteristics) of the landfill.”

Do any wastes require special treatment?

Like waste piles and surface impoundments, landfills must oblige with certain restrictions when dealing with ignitable, reactive, incompatible, or dioxin-containing wastes. Unlike other units, however, landfills are prohibited from placing bulk or noncontainerized liquid hazardous waste or hazardous waste containing free liquids anywhere in the landfill. Even placement of nonhazardous liquids is basically prohibited. According to the EPA, “there are only certain situations when containers holding free liquids can be placed in a landfill (e.g., small containers such as ampules, containers that are products such as batteries, or lab packs). If sorbents are used to treat hazardous wastes so that the waste no longer contains free liquids, the owner and operator must use nonbiodegradable sorbents.”

Are there any requirements for containers in landfills?

“To prevent significant voids that could cause collapse of final covers when containers erode, and to maintain and extend available capacity in hazardous waste landfills, containers placed in a landfill must be either at least 90 percent full or crushed, shredded, or in some other way reduced in volume, unless the containers are very small, such as ampules (§264/265.315).

Finally, there are special standards for lab packs or overpacked drums being placed in a landfill(§264/265.316). Lab packs generally contain small containers of a wide variety of hazardous wastes in relatively small volumes that are packed in sorbent material to prevent leaking. This sorbent material must be nonbiodegradable.”

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.

Surface Impoundment Inspection and Response Actions

Last week we talked about the design and operation requirements for surface impoundments. Today we’re going to continue on that topic by covering the inspection and response actions that must be completed by surface impoundment operators. In case you’ve forgotten, surface impoundments are a lot like landfill cells. The main difference being that surface impoundments are used for temporary storage or treatment and a landfill cell is designated for final waste disposal.

What are the Inspection Requirements for Surface Impoundments?

To start, we must note that these inspection requirements must be completed in conjunction with the general inspection requirements in §264/265.226. The first additional requirement deals with design and structural integrity of the land disposal unit. According to the EPA, “the owner and operator must inspect liners and covers for any problems after construction or installation and continue inspections weekly and after storms to monitor for evidence of deterioration, malfunctions, improper operation of overtopping systems, sudden drops in the level of the impoundment contents, and severe erosions of dikes and other containment devices.”

The second additional requirement addresses leak detection sumps. According to this rule, on a minimum of a weekly basis owners and operators of land disposal units like surface impoundments must monitor their leak detection sumps in order to measure the amount of liquid within them and to determine whether or not the action leakage rate (ALR) has been exceeded. Doing so makes sure that both the liner and the leachate pump are working efficiently. If owners or operators discover that the ALR has been exceeded they must notify the Agency and respond “in accordance with the response action plan.”

What Response Actions must Surface Impoundments comply with?

Much like the inspection requirements, surface impoundments must also comply with two types of response actions. According to the EPA, “the response action for the performance of the unit is determined by the terms of the response action plan, triggered when the ALR has been exceeded (§264/265.223). If the action leakage rate has been exceeded, the owner and operator must notify the Regional Administrator or authorized state; determine what short-term actions must be taken (e.g., shut down of the facility for repairs); determine the location, size, and cause of any leak; and send the assessments to the Region or authorized state.”

The other response action deals with emergency repair provisions in the case of a unit design failure at permitted facilities. The EPA specifies that “if there is an indication of a failure of the containment system (e.g., a sudden drop in the level of the contents not attributable to changes in the flow in or out of the impoundment), the surface impoundment must be removed from service.” If this happens the owners and operators of the surface impoundment must follow the plans laid out in the contingency plan. This would include any emergency repairs that need to be made.

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.

Surface Impoundments: Design and Operation

When the EPA was designing the cradle-to-grave system for managing hazardous wastes they developed nine different land disposal units. These units include landfill, surface impoundment, waste pile, injection well, land treatment facility, salt dome formation, salt bed formation, underground mine, and underground cave. Four of these nine unit types required additional technical standards set forth by the EPA. Today we will be covering the design and operating standards of one of those four, surface impoundments.

Surface impoundments are a lot like landfill cells in that, “both units are either a natural topographic depression, manmade excavation, or diked area formed primarily of earthen materials, such as soil.” Additionally, both may be lined with manmade materials. Their uses, however, are what make them so different. According to the EPA, “surface impoundments are generally used for temporary storage or treatment, whereas a landfill is an area designated for final waste disposal.” Because of this, the closure and post-closure standards are very different.

How are surface impoundments designed?

When the EPA began developing the design and operation standards for surface impoundments they operated with the goal of minimizing the formation and migration of leachate to the adjacent subsurface soil, groundwater, and surface water in mind.

According to the EPA, “these comprehensive technical requirements for surface impoundments are the minimum technological requirements (MTRs) mandated by RCRA. These sections require a double liner, a LCRS, and a leak detection system.” The MTRs are applicable to all new units, lateral expansions, and replacement units constructed or reused after July 29th of 1992.

First things first, we’ll talk about the double liner. This system includes, “a top liner to prevent migration of hazardous constituents into the liner and a composite bottom liner consisting of a synthetic geomembrane and three feet of compacted soil material.”

In addition to this liner system, the unit has to have a leachate collection and removal system (LCRS) which also serves as a leak detection system. According to the EPA, “The LCRS, along with the leak detection system drainage layers, must be designed with a bottom slope of at least one percent, be made of materials chemically resistant to the wastes placed in the unit, and be able to remove the liquids at a specified minimum rate. The LCRS itself must be designed to collect liquids in a sump and subsequently pump out those liquids. In addition to the performance and design requirements, the LCRS must be located between the liners immediately above the bottom composite liner, enabling the LCRS to collect the largest amount of leachate, while also representing the most efficient place to identify leaks.”

Making sure that material can’t leak back into the earth is not the only consideration that must be made, however. Surface impoundments also must be designed to prevent liquids from flowing over the top (called overtopping) and “ensure the structural integrity of any dikes.” The owner or operator must also develop a site-specific flow rate for leachate which is called the action leakage rate or ALR. This is used to indicate when a units system is not functioning as it should.

Because of the importance of these design regulations (and since none of the aforementioned technologies will work if the impoundment is not installed correctly or made of quality materials) the EPA requires a construction quality assurance (CQA) program to make sure that an impoundment meets all technical criteria. According to the EPA, “The CQA program requires a CQA plan that identifies how construction materials and their installation will be monitored and tested and how the results will be documented (§264.19). The CQA program is developed and implemented under the direction of a registered professional engineer, who must also certify that the CQA plan has been successfully carried out and that the unit meets all specifications before any waste is received.”

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.