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Assumptions Used in the Analysis Assumptions Used in the Analysis | TRI Explorer | US EPA

1998 was the first year that EPA collected information from the commercial hazardous waste treatment sector. EPA has taken steps to adjust for possible double counting of some disposal or other releases in TRI now that EPA collects information from this sector. The potential for double counting arises because some manufacturing facilities report transfers of chemicals to other facilities that may then report the disposal or other release of these chemicals. TRI facilities transfer off- site chemicals in waste to other facilities for disposal or other release. These other facilities can dispose of the wastes in on-site underground injection wells, landfills, disposal surface impoundments, in land treatment facilities, and other types of land disposal or, if metals are sent to a wastewater treatment facility, they may be discharged to surface waters. These other facilities generally are treatment, storage and disposal (TSD) facilities regulated under the federal Resource Conservation and Recovery Act (RCRA). As mentioned above, such facilities are in one of the industries required to report to TRI for the first time in the 1998 reporting year.

To avoid counting the transfers to the TSD facilities that are also reported to TRI as on-site disposal or other releases by the TSD facilities, off-site transfers for disposal or other releases to these TSD facilities have been omitted from tables that compare or summarize on-site and off-site disposal or other releases nationally or at the state level. Only the on-site disposal or other releases from the TSD facilities have been included. The tables contain a note at the bottom of the table if transfers were omitted for that particular table. In general, these transfers were omitted if the data were being analyzed from a national or state perspective. 1

In addition to the double counting adjustment described above, to remedy errors reported by facilities, EPA reclassified certain transfer codes for metals and metal compounds. EPA requires the transfer of metals and metal compounds for further waste management be reported as either a transfer to recycling or a transfer to disposal or other releases (i.e., a metal cannot be reported as combusted for energy recovery or treated because metal has no heat value and thus cannot be combusted for energy recovery and metal cannot be treated because it cannot be destroyed). In 1997, EPA added two new disposal codes to the TRI reporting form to provide more accurate reporting of metals and metal compounds: M41 (Solidification/Stabilization - Metals and Metal Category Compounds only) and M62 (Wastewater Treatment (Excluding POTW) - Metals and Metal Category Compounds only). Following the addition of these codes, if a facility incorrectly reported a code that indicated that an off-site location treated a metal, one of these new codes would be used. Specifically, if a facility used code M40 or M61 to indicate off-site treatment of a metal then the analysis used M41 or M62 instead, respectively.

1Conducting this exercise required that EPA match amounts transferred to TSD facilities with amounts reported by these TSD facilities by using the reported RCRA ID number. In some cases, these RCRA ID numbers were not reported correctly by the facility so there are some quantities that cannot be matched and, therefore, these quantities could not be omitted from the analysis.

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