Taking Stock Volume 16

2 Feature Analysis: Off-site Transfers to Disposal in North America, 2014–2018

2.2 Scope and Methodology

The Taking Stock methodology involves the compilation of data from the three North American PRTR programs for integration into the Taking Stock Online database. These data undergo a harmonization process that considers the differences among the reporting requirements of the national PRTRs with respect to pollutants and industry sectors. Through this process, Taking Stock enhances the ability of users to access regional PRTR data that are more comparable and understandable.

2.2.1 Data and information sources

For this special analysis of off-site transfers to disposal, North American PRTR data were obtained from Taking Stock Online. The analysis considers transfers reported between 2014 and 2018, with 2018 being the last year for which data were available for all three countries at the time of writing. Data for pollutants transferred across national borders for disposal (a subset of all transfers to disposal) were accessed via the Taking Stock Online Cross-border Transfers tool.

Readers should note that annual data are often updated by the national programs following quality assurance/quality control checks and facility revisions. Data are also periodically refreshed in Taking Stock Online to capture these revisions. The datasets used for the analyses in this report are from the NPRI, TRI and RETC datasets from March 2021, September 2020, and February 2020, respectively.

Interviews were also conducted with representatives of the North American PRTR programs and data from the three countries’ respective waste disposal regulatory agencies were examined. Finally, other sources of information (e.g., technical documents, news articles, studies) on industrial waste disposal practices and their associated environmental and human health risks were consulted.

2.2.2 Terminology and comparability of the North American PRTRs

The two fundamental concepts of PRTRs are: releases and transfers. Accordingly, pollutants are released on site to air, water, or land (with the latter including pollutants disposed of in or on the soil) by industrial facilities. In the case of transfers, pollutants are transported from an industrial complex to another site for recycling, treatment, storage, or disposal. Facilities that meet PRTR reporting thresholds are required to report the quantity of each specific substance (which may be contained in other waste) released or transferred in a calendar year.

The Taking Stock “off-site disposal” category covers a wide variety of practices employed by North American industrial facilities and reported according to unique national PRTR reporting requirements, making the comparison of data for the region challenging. To facilitate the analysis of the data presented in this chapter, an additional trinational effort was undertaken to review and “map” the transfers to disposal reported in the three countries. As a result, the Taking Stock Online database now includes the following six categories of transfers to disposal:

1. Confinement in landfills or surface impoundments
2. Underground injection
3. Disposal through land application
4. Off-site storage prior to disposal
5. Stabilization or treatment prior to disposal
6. Other disposal (unknown).

These Taking Stock categories, as well as each PRTR program’s corresponding terminology, definitions, and data fields, are presented in Table 6, which reveals some important differences among the three countries.^[11] Notwithstanding these differences, the availability of these disaggregated data through Taking Stock Online represents an important step towards improving the comparability of data across the region to enhance users’ understanding of the activities of North American facilities.

Readers are reminded that the terminology used in this report is unique to Taking Stock and is not necessarily that used by the national PRTR programs. This terminology reflects the best attempt to harmonize data from three different systems to obtain the most comparable picture of releases and transfers for the region.