Literature review of stabilization/solidification of volatile organic compounds and the implications for Hanford grouts

Abstract

PREFACE "his report meets requirements for Milestone 3.3, "Final Report (Based on l,iterature Findings) ot Selected Organics Treatment Options and Recommendations for tiantbrd Wastes," as described in Statement of Work TMG-SOW-H-91, Rev. 0, in support of tile Westinghouse l-tantbrd Grout Disposal Program. vii EXECUTIVE SUMMARY Stabilization/solidification technology is one of the most widely used techniques for the treatment and ultimate disposal of both radioactive and chemically hazardous wastes. Cement-based products, commonly referred to as grouts, are the predominant materials of choice because of their low processing costs, compatibility with a wide variety of disposal scenarios, and ability to meet stringent processing and performance requirements. Such technology is being utilized in a grout treatment facility by the Westinghouse Hanford Company (WHC) for the disposal of various wastes located on the Hanford Reservation, including 106-AN wastes. As of September 25, 1990, the U.S. Environmental Protection Agency (EPA) replaced the EP-Toxicity Procedure with the Toxicity Characteristic Leaching Procedure (TCLP) for determining whether a waste whose status is unknown is characteristically hazardous. This new procedure changed the status of many wastes throughout the United States from "not characteristically hazardous" to "characteristically hazardous" because several organic compounds were added to the metals and pesticides/herbicides already regulated. There was also concern that the potential presence of organics might make the Hanford grouts subject to the land-ban restrictions, WHC was concerned that the double-shell t_ks supernate was potentially characteristically hazardous by TCLP definition, or subject to land-ban restrictions, because of the suspected presence of the following organics: acetone, methyl ethyl ketone, methyl isobutyl ketone, and I,l,l-trichloroethane. These four organics are defined as volatile organic compounds (VOCs) by EPA. (The TCLP lists extractant-concentration limits for a large number of organics not regulated by the EP-Toxicity procedure, and the limits for these four are nonlisted, 7.2 mg/L, nonlisted, and 30 rag/L, respectively. Land-ban restrictions limit the TCLP leachate concentration of acetone to 0.59 mg/L. All tbur compounds are targeted for treatment under the land-ban restrictions and within the waste codes by the best demonstrated available technology (BDAT). (The BI)AT reference numbers are 222, 34, 220, and 45, respectively.) t Even if the supernate were not characteristically hazardous by TCLP definition, WHC was concerned that the regulators of EPA _nd the state of Washington might still require proof of the organic retention capabilities of the grout and engineered barriers because of the potential presence of these organics. A literature search on stabilization/solidification of VOCs revealed three previous reviews on this topic, two covering the pre-1985 period and one covering the post-1985 period. Not all of the relevant literature was in hand at the time...

Isopar L Release Rates From Saltstone Using Simulated Salt Solutions

“…Volatile organic compounds (VOCs) are usually not stabilized in this manner because of loss upon initial mixing prior to curing. 5 One case does exist in which it may be useful to treat VOCs via solidification, and that is the case where the VOC is at a very low concentration in the waste being stabilized.…”

Evaluation of final waste forms and recommendations for baseline alternatives to group and glass

“…Some stem from the fact that grout is inadequate for a large number of wastes [337]. For instance, some important wastes can be leached too readily from grout; these include wastes that contain radionuclides [395] or volatile organic compounds [397]. Also, the occurrence of incomplete chemical reactions (viz., hydrolysis) in grout can lead to detrimental, time-dependent, leaching behavior, and the hydration of grout can be critically inhibited or stopped altogether under ambient conditions by some waste species (e.g., organics).…”

Feasibility study on the solidification of liquid low-level radioactive mixed waste in the inactive tank system at Oak Ridge National Laboratory, Oak Ridge, Tennessee

“…While use of the BDAT is not absolutely required, the treatment that is used must meet the treatment levels specified by the BDAT. There is currently some debate as to whether the applicable regulatory limits for waste forms containing organics are the total concentration limits or the TCLP limits, and whether the TCLP test is a valid test for measuring the leaching of organics (Brown 1992, Spence and Osborne 1991, Wiles and Barth 1992.…”

“…Results for physical tests performed for the IWT demonstration on VOCs and heavy metals were satisfactory except for freeze-thaw tests. According to the review by Spence and Osborne (1991), the Hazcon process overcomes the tendency of oils to interfere with the cement set but does not enhance retention of the organics.…”