If it is not possible to get actual weights from your campus hauler (company/vendor that picks up your trash, recyclables, etc.), you may still be able to generate reasonably accurate numbers by doing volume-to-weight conversions.
Definition > A volume to weight conversion involves obtaining the total volume of waste generated on campus and applying an industry standard weight per unit volume to estimate the total weight.
While the waste weights will be an estimate using this strategy, the total volume of waste cannot be an estimate. Total volume can be determined using the following data points: The number of bins emptied, the total capacity of the bin, and the volume of the bin."
For smaller carts you can pop the lids on a few and get a feel for how full they are on average and use this to multiply across all carts. For larger dumpsters, perform a visual inspection and note the approximate dumpster "fullness" (i.e. 1/4 full, 1/2 full, 3/4 full, or completely full.) Use the dumpster capacity to determine total volume of waste. Ex: if an 8 yard dumpster is roughly half full when emptied, 4 yards should be used to calculate the weight."
Once you have determined the total volume capacity, you will need an average “per yard” or “per gallon” weight to use as a multiplier to estimate weight.
- The first and best option is to weigh sample bins to get an average weight per unit volume (a "multiplier") for your campus and apply it to all waste during the competition. Collection haulers not willing to weigh every week may nonetheless be willing to do a dedicated campus route on one or two occasions to create these multipliers. If so, be sure to arrange to ride along with your hauler to learn how to determine how many dumpsters are emptied on that route and how full they are so you can assign the number of gallons or yards to the weight.
- Second option > If recyclable materials are collected in bags, weigh 20 or 30 bags to get an average weight and then track the number of bags taken out each week going forward. If haulers are unable to provide the use of their scales, scales might be available on campus within academic departments such as Sciences, Dining services or at sports facilities.
- Third option > If you are not able to generate your own campus-specific sample weights as the basis for creating multipliers, use the US EPA has generic volume-to-weight formulas as a backup. Note: because the weight of recyclables and organics or trash can vary significantly from one location to the next, these EPA multipliers may not accurately reflect the actual weight of materials on a particular campus. Coordinators should use their judgment in deciding whether their actual materials are likely lighter or heavier and make adjustments as necessary. RecycleMania rules require schools to use a good faith best judgment in reporting all numbers even when relying on EPA, waste hauler or other 3rd party multipliers. If you have questions about this, contact the Campus Race to Zero Waste team for advice.