Compliance Corner.

Contaminated Soil Standards

When EPA initially developed the LDR treatment standards, they were concerned primarily with process wastes being generated on an ongoing basis by industry. The agency was not initially concerned with soil that might be contaminated with hazardous waste. Over time, it became obvious that hazardous soil was frequently produced as the result of spills of product/waste and as a result of remediation activities. If this hazardous soil was to be land disposed, it had to meet the treatment standards in §268.40 that had been developed for process wastes. The end result of this regulatory approach was that contaminated soil was frequently being incinerated (an expensive proposition) because many of the §268.40 treatment standards were based on that technology. The high costs of treating contaminated soil in this manner adversely affected the willingness of many parties to undertake site remediation activities. Realizing soil is a completely different matrix than process wastes, the agency eventually developed alternative treatment standards for contaminated soil. These standards are codified in §268.49.

Contaminated soil will be subject to the LDR program only if 1) it is hazardous (i.e., it exhibits a characteristic or contains a listed waste), and 2) it is generated (i.e., excavated). If hazardous soil is excavated and will be land disposed somewhere, three options are available for treating the soil under the LDR program:

1. The soil can be treated to meet the nonwastewater treatment standard in §268.40 for the hazardous waste contaminating the soil. For example, if product benzene (U019) is spilled on soil, the contained-in policy applies the U019 code to the soil. The associated nonwastewater treatment standard for this waste code is 10 mg/kg benzene. Treating soil to meet a §268.40 standard may not be the best option because, as mentioned previously, meeting a standard of 10 mg/kg benzene may require the use of a very efficient (but very expensive) treatment technology, such as incineration.
2. The generator/TSDF may request a treatability variance for the contaminated soil per the provisions of §268.44. While this might have been a viable option when the only other alternative was to treat soil to the §268.40 standards, it is generally not an attractive option today. Any time a party requests special consideration from EPA or the state, the process is likely to be expensive and time consuming, and it is quite possible the agency will not be willing to issue a variance.
3. The best option is to use the alternative soil treatment standards of §268.49. EPA refers to the alternative treatment standards as “90% removal capped at 10 times UTS.” As illustrated in Figure 1, the initial concentration of “constituents subject to treatment” is determined. Treatment must achieve a 90% reduction in total concentration (refer to constituent A), unless that level of treatment would reduce the concentration to below 10 times the UTS level for the constituent. In no case does treatment have to reduce the concentration to below this 10-times-UTS floor (refer to constituent B). Therefore, the treatment provided under this option allows residual contaminant concentrations in soil to be at least 10 times greater than for Option 1 above.

The required 90% removal efficiency under the alternative treatment standards allows the use of less expensive technologies than would be required for Option 1, which relies on incineration-like technologies, typically performing at 99.99% or greater efficiency.

“Constituents subject to treatment” for these alternative soil treatment standards are defined as any constituents in §268.48 that are reasonably expected to be present in the soil at concentrations greater than 10 times UTS levels. [§268.49(d)] As with UHCs, fluoride, selenium, sulfides, vanadium, and zinc are not constituents subject to treatment.

Generators of hazardous soil are not required to monitor the soil for the entire list of constituents in §268.48 to determine the “constituents subject to treatment.” Instead, EPA allows generators of hazardous soil to reasonably apply knowledge of the contaminants that are likely to be present in the soil and use that knowledge to select appropriate constituents, or classes of constituents, for monitoring. [May 26, 1998; 63 FR 28609]

The alternative soil treatment standards provide different data collection options for remediation projects:

• If the 90% treatment standard is selected and analytical testing is used to confirm compliance, two sets of samples are required—one at the point of generation and one after treatment.
• If the 90% treatment standard is selected and process data are used to show that the process always operates at greater than 90% efficiency, no routine sample analyses would be required. Instead, compliance could be confirmed by monitoring process variables, controls, and operating conditions.
• If the 10-times-UTS option is chosen, only one set of samples is required—after waste treatment.

The above discussion on how the alternative treatment standards for soil are applied is taken from Guidance on Demonstrating Compliance With the Land Disposal Restrictions (LDR) Alternative Soil Treatment Standards, EPA/530/R-02/003, July 2002, available from https://www.epa.gov/sites/default/files/2016-01/documents/soil_f4.pdf.

At a number of areas around our country, natural background concentrations of certain constituents in §268.48 (e.g., arsenic) are high. As a result, such constituents may be identified as constituents subject to treatment in hazardous soil (e.g., resulting from a recent nonarsenic spill), and the alternative soil treatment standards may require treatment of these constituents to levels below natural background concentrations. EPA doesn’t think it would have the authority to require that. Therefore, in situations where treated soil will continue to be managed onsite (e.g., as backfill) or in an area with similar natural background concentrations, such constituents will not have to be treated below background levels. Conversely, if the soil will be sent offsite for land disposal, full compliance with the alternative soil treatment standards is required since “the agency believes that natural background concentrations onsite will not automatically correspond to natural background concentrations at a remote land disposal facility.” [63 FR 28609] For the purpose of this provision, EPA considers natural background concentrations to be those in soil which has not been influenced by human activities or releases. The agency will require individuals who want to cap LDR treatment at natural background levels to apply for and receive a treatment variance per §268.44(h)(4).

Soil contaminated with characteristic wastes

Soil contaminated with characteristic waste is subject to the land disposal restrictions if it exhibits a characteristic when it is excavated. However, “It is conceivable that soil could be contaminated with a characteristic hazardous waste [e.g., due to a spill] and yet not display a hazardous characteristic at the point of generation due to dilution in the soil matrix or to breakdown or alteration of the constituents in the soil environment. If this soil does not exhibit a characteristic when it is generated (excavated), then LDR requirements do not apply.” [RO 14547]

If contaminated soil exhibits a characteristic of ignitability, corrosivity, or reactivity, these characteristics must be eliminated prior to disposal per §268.49(c)(2). In addition, if any constituents in §268.48 are reasonably expected to be present in the soil at concentrations greater than 10 times UTS, they must also be treated to meet the 90% removal capped at 10-times-UTS standards.

Soil contaminated with listed wastes

EPA included in the regulations [§268.49(a)] a rather complex table to use in determining if soil contaminated with listed wastes is subject to LDR standards. This chart can be simplified to a single statement: Soil contaminated with listed waste must comply with LDR treatment standards unless the soil was contaminated before LDR standards applied to the listed waste and a no-longer-contains determination has been obtained from the agency at the point of generation (excavation) of the soil. Table 2 in Appendix VII of Part 268 provides these effective dates.

Once it is determined that soil is subject to treatment standards, the next step is to determine which contaminants are subject to treatment. Per §268.49(d), constituents subject to treatment are those constituents in the UTS table (§268.48) that are reasonably expected to be present in the soil at concentrations greater than 10-times-UTS levels.

When using the alternative treatment standards for soil containing a listed waste, the constituents subject to treatment may include constituents that do not require treatment under the §268.40 treatment standard for the applicable waste code(s). The treatment standards in §268.40 for listed wastes do not require identification or treatment of UHCs. However, under the alternative treatment standards for soil, generators must identify and treat all constituents subject to treatment that are reasonably expected to be present in listed and characteristic soils. [RO 14628]

If soil is contaminated by a waste that consists only of nonanalyzable constituents, the soil must be treated by the specified method for the nonwastewater form of the waste as given in §268.40. A constituent is nonanalyzable when 1) the appropriate §268.40 listing specifies a treatment technology, and 2) there is no concentration-based limit in the §268.48 UTS table. [May 11, 1999; 64 FR 25410–1] For example, if product formaldehyde (U122) is spilled on soil, formaldehyde is a nonanalyzable constituent. (We can tell this because the treatment standard for U122 in §268.40 is a specified method—CMBST, and formaldehyde does not have a concentration-based limit in §268.48.) Therefore, our U122-contaminated soil must be combusted; it cannot be treated by the alternative treatment standards of §268.49.

If soil is contaminated with both analyzable and nonanalyzable constituents, the alternative standards of §268.49 may be used, and only analyzable constituents present at greater than 10 times UTS would be subject to treatment. [See §268.49(c)(3).] EPA expects that treatment of the analyzables will also provide adequate treatment of the nonanalyzable constituents. Where the analyzable and nonanalyzable constituents are not both organics, however, EPA believes that treating the analyzable constituents may not serve as a surrogate for treatment of the nonanalyzables. Such cases would have to be addressed with regulators on a site-specific basis. [May 11, 1999; 64 FR 25410]

Dealing with residues from soil treatment

After contaminated soil is treated, two treatment residues remain: 1) treated soil (which may still contain relatively high contaminant concentrations), and 2) nonsoil treatment residues such as washwater. The regulatory status of these residues is determined using the derived-from rule. For example, if the soil was originally contaminated with a listed spent solvent (e.g., F005), the derived-from rule states that both the treated soil and nonsoil residues continue to be F005 listed wastes. Hence, the treated soil would have to be disposed of in a Subtitle C landfill (unless a no-longer-contains determination is obtained from the state). The nonsoil residue must be treated to meet the §268.40 standards for F005 prior to land disposal.