Radioactive lead solids that are wastes and that exhibit the toxicity characteristic for lead (D008) must comply with the land disposal restrictions (LDR) treatment standard for the Radioactive Lead Solids Subcategory, which is a type of macroencapsulation that is abbreviated as MACRO (see 40 CFR 268.42 Table 1). EPA established MACRO as a required method of treatment only for the Radioactive Lead Solids Subcategory for D008 wastes, and does not require the use of MACRO for other subcategories or for hazardous debris.
D008 lead-containing waste must be treated and properly disposed because the waste is not reusable or recyclable due to its radioactive nature. Radioactive lead solids (RLS) include, but are not limited to, all forms of lead shielding and other elemental forms of lead. These radioactive lead solids do not include treatment residuals such as hydroxide sludges, other waste treatment residuals, or incinerator ashes that can undergo conventional pozzolanic stabilization, nor do they include organo-lead materials that can be incinerated and stabilized as ash. This D008 waste subcategory consists of nonwastewaters only.
RLS is often commingled with debris and non-debris wastes, but RLS waste materials are not "debris" by regulatory definition under 268.2(g). Therefore, commingled RLS with debris requires the use of the MACRO technology standard if the waste cannot be readily or safely separated into its individual components for separate immobilization methods of treatment (i.e., as hazardous debris and RLS).
The MACRO technology standard also specifically does not include any material that would be classified as a tank or container according to 40 CFR 260.10 (40 CFR 268.42, Table 1). Compliance with the MACRO technology standard requirement is achieved with the application of surface coating materials using polymeric organics (e.g., resins and plastics) to completely encapsulate the waste to substantially reduce surface exposure to potential leaching media. Low-Density Polyethylene (LDPE) is a polymeric organic used to meet the MACRO standard.
On the other hand, hazardous debris can be treated by several technologies, including macroencapsulation, and has a similar but separate standard under 40 CFR 268.45. The definition of macroencapsulation in Table 1 of 40 CFR 268.45 for hazardous debris differs in two ways from the definition of the MACRO technology standard specified for the Radioactive Lead Solid Subcategory. First, it does not specifically prohibit the use of containers. Second, it has a performance standard, stating that:"Encapsulating material must completely encapsulate debris and be resistant to degradation by the debris and its contaminants and materials into which it may come into contact after placement (leachate, other waste, microbes)." This separate definition of macroencapsulation allows container-based macroencapsulation technologies to be used to comply with the LDR technology standard for mixed waste debris.
As a result of the differing definitions, mixed waste debris composed of co-generated radioactive lead solids and hazardous debris must either be managed entirely as D008 Radioactive Lead Solids Subcategory wastes, which requires treatment using the MACRO methods as defined in 40 CFR 268.42 Table 1, or be separated into its component parts by ordinary means so that the RLS component and the hazardous debris component can be treated separately.
The following memoranda also provide clarification on the macroencapsulation of lead:
Memo, Cotsworth to Lawrence; August 9, 2001 (RCRA Online #14554)
Monthly Call Center Report Question; April 1997 (RCRA Online #14091)
Memo, Kinch to Igli; September 19, 1995 (RCRA Online #13762)
Memo, Lowrance to Guida; July 30, 1990 (RCRA Online #13393)
These memoranda are available in the at the RCRA Online database.