California TDP Catalog

Contractor’s Report to CalRecycle 37 Step 4: Key data from these sources is entered into a customized spreadsheet model and scrutinized to identify all flows as completely and accurately as possible while avoiding double counting. This is an iterative process in which researchers identify issues and follow up with facilities to refine the analysis. All reported quantities are converted tons. With the exception of retreaders, surveys request flow data in tons. Retreaders report the number of different types of tires retreaded and their average weight. Occasionally facilities provide data in the number of tires or cubic yards, and the most accurate conversion factor available is used to convert to tons . 13 WTMS data are used to estimate the approximate magnitude of tires flowing to and from facilities. This is very helpful in eliminating double counting, and also helps identify issues to resolve through interviews. However, WTMS data generally provide only rough approximates of actual tonnage flows due to conversion factor issues. CalRecycle’s WTMS database provides all data in PTEs (defined as 20 pounds). But the basis for WTMS data are Comprehensive Trip Logs (CTLs) submitted by haulers and facilities, which may enter amounts in either tons, cubic yards, or the actual number of tires (regardless of the tire size or type). CalRecycle converts cubic yards to PTEs using 10 PTEs/cubic yard, which generally tends to under-estimate actual tonnages. For this report, WTMS data is downloaded in PTEs and then converted to tons using the 20 pound per PTE standard. Where necessary, researchers also examine a sampling of CTLs for a given facility to analyze potential errors related to conversion factors. When the final analysis is complete, tons are also converted to PTEs to allow comparison with past reports. Methodology Refinements The methodology for conducting this report has been relatively unchanged since 2007. However, refinements are made from time to time. In this year’s report a few changes to the categories used to report the main findings in Table 1 were changed: • Used Tires (Export) was grouped in the reuse category rather than the export category as in previous reports. • Under crumb rubber, the “Molded and Extruded” and “Other” categories were combined to form the new “Molded and Other” category. • The Export category was relabeled as “Exported TDF”, with two subcategories, “baled waste tires” and “size-reduced TDF.” 13 For example, according to the U.S. Tire Manufacturers Association (formerly the Rubber Manufacturers Association), on average light duty tires such as scrap passenger tires weigh 22.5 pounds, commercial tires such as scrap truck and bus tires weigh 120 pounds, and the average of all light duty and commercial scrap tires (excluding off-the-road tires) is 32.8 pounds. Source: “2013 U.S. Scrap Tire Management Summary.”November 2014, page 4.