TCLP concentrations

During bench-scale studies on ACT using sediments from the New Bedford Harbor Superfund Site, the Toxicity Characteristic Leaching Procedure (TCLP) concentrations of many contaminants increased or remained unchanged following treatment. Based on these results, researchers stated that solidification/stabilization methods such as ACT were not appropriate for the treatment of polychlorinated biphenyls (PCBs) or semivolatile organic compounds (SVOCs) at the site. The study also indicated that the compressive strength of ACT [45 to 80 pounds per square inch (psi)] was relatively low compared to other solidification/stabilization materials that were tested. 

The most commonly used action levels for determining whether a waste stream exhibits toxicity characteristic and therefore is hazardous under RCRA are the Toxicity Characteristics Leaching Procedure (TCLP) concentrations for 24 organic compounds, 6 pesticides, 2 herbicides, and 8 metals as described in 40 CFR Part 302. Appendix 3 presents a list of these compounds and their maximum TCLP concentrations, which are frequently referred to in project work. 

RCRA was passed to manage nonhazardous and hazardous wastes and underground storage tanks, with an emphasis placed on the recovery of reusable materials as an alternative to their disposal. This act introduced the concept of the separate management of hazardous and nonhazardous wastes, and defined procedures to identify whether a waste is hazardous or nonhazardous. A waste exhibits the characteristic of toxicity, classified as a hazardous material, if the concentration of any of 39 selected analytes in the Toxicity Characteristic Leaching Procedure (TCLP) extract exceed regulatory action levels. 

A solid waste containing lead or lead compounds may be defined as a hazardous waste if it exhibits the characteristic of toxicity. The waste is said to exhibit the toxicity characteristic if the lead concentration in the extract obtained by subjecting a sample of the waste to the TCLP exceeds 5.0 mg/L. Tetraethyl and tetraethyl lead are combustible. If they are in sufficient quantity in a waste, tetraethyl lead may show an ignitability characteristic. More details on the regulatory requirements are presented in Chapter 7. 

Health-based limits for exclusion of waste-derived residues TCLP extract concentration limits for metals (lead)... 

The next phase of the experiment was the determination of the kinetics involved in the metal-binding reactions within the CHEMFIX product matrix. Eight (8) samples of each SSM were treated by the CHEMFIX process at the optimum reagent ratio. A TCLP extraction was performed 0, 1, 3, 5, 8, 24, 48 and 72 hours after treatment. The TCLP leachate from each sample was analyzed for target metals concentration. 

TCLP LEACHABLE METAL CONCENTRATIONS OF CHEMFIX TREATED AND UNTREATED SAMPLES... 

TREATED SSM 1 TCLP LEACHATE METALS CONCENTRATION, mg/1 AFTER TREATMENT... 

The data shows an immediate decrease (the difference between untreated and 0 hours after treatment) in the TCLP leachable metals concentration for all seven metals. This indicated that the metals were bound immediately upon being treated. There would be no threat for contaminant leaching during the period it took for the CHEMFIX product to physically solidify. In addition, the TCLP leachable metal concentrations of those samples that were not allowed to cure (0 hours after treatment) all passed the TCLP regulatory limits. Therefore immediately after treatment the material can be classified as non-hazardous. 

The Clean Air Act of 1990 has made trace metal content in fuels and wastes the final ash-related compositional characteristic of significance. Considerable attention is paid (ca 1993) to emissions of such metals as arsenic, cadmium, chromium, lead, mercury, silver, and zinc. The concentration of these metals in both grate ash and flyash is of significance as a result of federal and state requirements of particular importance is the mobility of metals. This mobility, and the consequent toxicity of the ash product, is determined by the Toxic Characteristic Leaching Procedure (tclp) test. Tables 8—10 present trace metal contents for wood wastes and agricultural wastes, municipal waste, and refuse-derived fuel, respectively. In Table 8, the specific concentration of various components in the RDF governs the expected average concentration of trace metals. 

Although the maximum allowable concentrations of the regulated eight metals (and pesticides, herbicides, and insecticides) do not change from those listed under the EP toxicity, the new TCLP analytical procedure may make it more difficult for listed wastes to stay under the allowable concentrations (Table 29.3). 

Contaminant Concentrations in Simulated Supemate Waste from Hanford Tank, their Waste Forms, and the TCLP Results. 

Toxicity (waste code D004-D043)-Liquid wastes or extracts from waste solids that fail the Toxicity Characteristics Leaching Procedure (TCLP) analytical test because they contain certain designated metals, pesticides, or organic chemicals at concentrations equal to, or in excess of, specified regulatory limits. 

The program involved leaching selected industrial chemical process residuals with leachate derived from municipal refuse in a pilot-scale field facility measuring the concentration of the compounds which leached from the wastes and comparing these field concentrations to those in the EP and other candidate leaching tests. The Toxicity Characteristic Leaching Procedure or TCLP, is the outgrowth of these studies. 

In assessing how well the TCLP compared with the wastes examined in tlie lysimeter model, the distributions of the actual and absolute percent differences were examined. Results of these analyse for the acetate buffer extractions indicate that 75% of the target compound concentrations in the TCLP duplicate field lysimetei target concentrations within one standard deviation. This is particularly significant since the laboratory test duration is lb hours, whereas the field lysnncter experiments were run for about i months. 

EPA lists MEK peroxide as likely to leach dangerous concentrations of toxic chemicals into ground water and regulates it under TCLP. Dimethyl phthalate has been identified as a priority pollutant and is regulated under the Clean Water Act, the Clean Air Act, RCRA and the Superfund Amendment. 

For remediation purposes it is important to determine Pb concentrations in soils using the toxicity characteristic leaching procedure (TCLP) (U.S. EPA, 1992). Soils that have TCLP-Pb concentrations below 5 mg L" are considered non-hazardous and can be disposed of in landfills. Although the procedure has little scientific value, it has been used widely for evaluating soil contamination and remediation. 

As mentioned in Section 15.4.1, total Pb concentrations varied greatly at the site, reaching levels of 30 g kg at a depth of 10 to 20 cm Also, P concentrations are variable at each P treatment because different sources of P were tested. Nevertheless, the data in Table 15.2 address the efficiency of the treatments to reduce TCLP-Pb even with the Pb variability at the site. 

In the control plot (TO) where no P amendment was applied, TCLP-extractable Pb concentrations at the surface soil (0 to 10 cm) far exceeded 5 mg L (Melamed et al., 2003). Similar to the distribution of total Pb, the highest concentration of TCLP-extractable Pb was observed at 10 to 20 cm. Even at a depth of 20 to 30 cm, TCLP-Pb still exceeded the critical level. The results showed that P amendments were effective in reducing the TCLP-Pb to below the critical level in the surface soil. These results are of great significance with respect to disposal of the soil, because they show that P amendments can amend the soil to a material that would be considered nonhazardous. Although P treatments did reduce TCLP-Pb in the subsurface soils (10 to 20 cm), TCLP-extractable Pb concentrations in Tl and T3 treatments were still higher than the critical level, except in the T2 treatment. Table 15.2 summarizes all the data for a contaminated site at Jacksonville, Florida. 

TABLE 15.2. Total Lead and Phosphorus Concentrations, pH, Residual Pb, and TCLP-Pb in the Soil ... 

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