Your waste bills, produced by your waste contractor should be the primary source of data for examining waste generated combined with raw material purchase records to the facility/organization. The contractor(s) that collects the waste from your organization is required to provide you with waste bills or invoices. These documents should detail the quantity of waste that is collected.

This provides a variety of useful data points including the financial data for processing the waste which can be utilized to assist in calculating the savings that can be achieved as a result of implementing improvements or to estimate the cost of inaction with regards to a particular waste stream. Presenting this information simply and clearly and using it to demonstrate payback on any investment required (whether financial or staff time), will often be essential in obtaining management commitment to any proposed strategies.

The quantity of raw materials and supplies that your organization has bought is possibly detailed in purchase orders. These documents are usually held by an organization’s finance or procurement teams. This financial data can be used to determine savings that result from implementing improvements. It can also help calculate the potential cost of inaction. To obtain management commitment, try presenting this information in a clear and simple way. Use the information to demonstrate payback on any investments made, whether that be through capital or staff time.

Keep the following points in mind when looking at bills/invoices or purchase records:

• Understand what information relates to your organization’s actual consumption or waste generation. Additional charges (e.g., skip rentals or delivery costs) do not reflect on your organization’s waste or resource use. Any landfill tax or other environmental charges, or the cost of reprocessing recyclable material, however, do factor in. These charges will vary depending on how efficiently you use the raw materials you have purchased.
• Determine if the quantities you see in your documents are based on actual or estimated consumption (e.g., the number of bins may have been recorded but bins may not have been completely full each time)
• Make note of the time period of the information. Is every collection of waste or delivery of supplies documented individually or do you have the total quantity for the year? Information lumped into a longer time period (e.g., one year) will not show shorter-term fluctuations in consumption or waste. These shorter-term quantities can help you to determine improvement opportunities.
• Be careful not to look solely at financial information. Changes in price may hide any changes in consumption and waste generation patterns.
• If possible, speak to your raw materials provider or waste collector to ask if they can provide more detailed information on your bills (e.g., breakdown of waste by material and associated volume or weight)

Over time, you may find that it is better to take direct measurements of the raw materials your organization uses. The more accurately and more frequently you measure your raw material consumption, the easier it will be for your organization to identify areas for improvement. This is because frequent monitoring will alert you to short-term fluctuations in consumption. Ideally, you will be taking measurements once every one or two weeks.

Measurement options for waste materials:

• Weigh small, partially filled containers or bags on calibrated scales.
• Fit piped systems with accurate flow meters. Where possible, use electronic data loggers (this is for liquid raw materials – e.g., water as a raw material).
• Count the number of metered doses (e.g., the amount being added to a mixing vessel).
• Decant large containers such as drums using set measurements (e.g., liter jugs).
• Count the number of part bags, drum loads, shovel loads, etc.

Measurement options for materials that have stock levels:

• Fit tanks with calibrated electronic level meters or load cells.
• Mark transparent containers such as intermediate bulk containers (IBCs) to indicate fixed intervals so you can measure against a scale.
• Use straight and properly calibrated dipsticks.

Waste composition analysis is where you identify and measure the materials being disposed. This involves manually separating and weighing various waste materials. This can be useful where accurate waste information is not available. This analysis can be done through a simple four-step process and can help you to understand and quantify your waste stream(s). Both internal and external bins can be analyzed.

1.  Determine the number and types of bins

Determine the types of bins your organization uses and how many of each you have. Common bin sizes include: 90 liter, 120 liter, 140 liter, 240 liter, 360 liter, 660 liter, 1,000 liter, 1,100 liter and 1,280 liter. Your organization may also use 205-liter drums or 1,000-liter intermediate bulk containers (IBCs) to store waste. You may also find your organization uses front-end loader (FEL) bins, rear-end loader (REL) bins, compactors, and skips.

2.   Determine the uplift frequency

Find out how often your bins are emptied by checking your waste bills/invoices. It may also be useful to speak with relevant colleagues.

3.    Determine the content of the bins and estimate the fill rates.

Use a sample of bins (minimum 10%) for each area of your site. This selection should represent the typical waste disposed of in that area.

If possible, empty the selected bins and weigh the different components found in each. This will be the most practical approach. If this is not possible or practical, look into the bins and estimate the volume of each type of waste disposed. When making your estimations, bear in mind how different materials stack and compress.

Tip: Use clear bin bags to allow you to easily check what is being disposed of.

Ideally, you should monitor waste and raw material use continuously and measure as many materials as possible. Often it is more practical to take occasional measurements and use that information to make estimates where you have unknown information, or you wish to target a specific area, particular process, or raw material and/or waste stream. This can be done through trials and taking samples.

A trial involves changing one variable in an equation and looking at the impact on the rest of the process. For example, you might alter the settings on a piece of equipment and see how the change affects the amount of waste generated. When completing a trial, it is imperative that all other variables are kept the same, so you get an accurate understanding of the impact.

Data sampling involves collecting a sample of information and then scaling it up to give an estimate of the total for a longer period or over a larger area. For example, it may not be feasible to collect accurate data on every bin on your business’s site, but you could collect data on a smaller set of bins and then scale the data up to represent all the bins on the site. When data sampling, consider the following:

• Make your samples as large as possible.
• Sample over a representative cycle (i.e., day/shift/production cycle).
• Note any assumptions when scaling the data (i.e., working days in a year vs actual days).
• Provide as much detail as possible in your initial measurements. This can greatly affect the accuracy of your estimations.
• Repeat your sample collections as often as possible. This will help you to monitor fluctuations in your waste or raw material consumption as well as understanding (and subsequently reporting) the positive impact waste reduction initiatives have had.