EC 004: Dumpster Dives


For the 4th episode, I am posting the 3rd part of a 5 part video course, called W.A.S.T.E. Walks.

This episode introduces the “Dumpster Dive” to help reduce landfill charges and the amount of trash or rubbish going to the landfill.

You can view the video version of this course for free!

The following episode will cover the last walk, Energy Walks.

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Dumpster Dives, also called Waste Audits, are a great place to start for reducing solid waste and landfill charges in your facility or company.

This approach will help prioritize the opportunities, baseline current recycling and composting practices and success rates, and engage your employee to drive behavior changes.

What is a dumpster dive?

Similar to when you climb into a trash dumpster to look for items of value, a dumpster dive is an event to help companies and organizations make improvements to what leaves their facility as solid waste.

First, the trash, compost and recycling (called solid waste) is collected over a period of time, such as one day, multiple days, or one week. The duration of collection will vary, but should be representative of typical results from all areas. There should be no warning or announcement of the collection, in order to avoid skewed or modified results.

Next, employees representing each area of the organization will be asked to sort through the solid waste. They will be provided protective equipment, such as gloves, safety glasses and body suits if necessary.

After separating the items, the employees will group like items together. The categories can be pre-defined or determined after the sort.

The weight is taken for each category of items, and recorded into a spreadsheet. The results are added together, and each category is calculated as a percentage of the overall weight. A pie chart is created from the weight totals from each category. In addition, they provide feedback on the quality of the recycling and composting, to ensure the bins are not being contaminated.

The results are presented by the team to management, along with ideas and opportunities they observed or brainstormed. Ideas will include ways to reduce consumption of items, setup areas to collect and segment these items in the facility, or replace with more eco-friendly, recyclable or compostable options.

Here are some images from events held at a residence hall at the University of Iowa.

The upper left shows the contents of a container full of plastics.

The upper right shows the different categories identified during the dumpster dive.

In this event, the following categories were used:

  • Trash, with no option to recycle or compost currently
  • Food waste/scraps that could be composted
  • Liquids that could be composted
  • Mixed paper that could be recycled
  • Cardboard that could be recycled
  • Mixed plastics that could be recycled
  • Redeemable plastics that could be recycled and could generate income
  • Non-redeemable metals that could be recycled, but no income received
  • Redeemable metals that could be recycled and could generate income
  • E-waste that could be recycled
  • Plastic bags that could be recycled
  • Glass that could be recycled

They identified that food waste and liquids made up 33% of the landfill, and could be composted. In addition, 50% could be recycled. 27% of the solid waste could not be recycled or composted at this time, and was the only legitimate amount that should have been in the trash.

These results make it evident that there is plenty of room for improvement, even on a college campus. Imagine how these results might compare to your business or organization.

Here is the layout used at one of the dumpster dives at the University of Iowa.

There are two sort tables, and the volunteers stand next to each table.

Each volunteer was provided training on the dumpster dive (and what should be included in each container).

They are also required to gown up with Tyvex white suits and put on gloves and safety glasses for their protection.

The green numbered boxes in the middle represent the containers, each labeled as a different material or waste stream, such as batteries, metals, mixed plastics, etc.

There are two experts or referees, who dump out the trash cans on the left onto the table, so the volunteers can begin sorting the items.

If they aren’t sure if the item goes into a certain container, the experts help them out. They also review the bins to make sure the volunteers selected the correct bins. The expert role is very important to the success of the dumpster dive.

When the containers are full, the experts take away the full container and replace it with an empty container. Then they carry the full container over to the weigh station so the weight can be recorded (after taking out the weight of the container), and then the contents of the container are placed into the correct final container (either trash, recycling or composting bin, as shown at the far right).

When all the trash cans have been sorted, the final weights are collected and totaled, and a preliminary report is generated and shared with everyone involved. An official report with recommendations and next steps is compiled and sent out after the event.

There is a video in the next lecture that you can watch, to get a better idea how the event was conducted.

Most of the waste audits are taking place at high schools and college campuses.

The University of Iowa found that 75% of the trash could have been recycled or composted

Oklahoma University found that 50% of the trash weight could have been recycled

These audits also identify whether there is contamination in the recycling, when items are getting into the recycling or composting bins that should not be in there, which can unfortunately cause the entire recycling or compost bin to be thrown into the trash.

So there are two ways that recycling and composting can fail: items are being put in the trash, when they should be composted or recycled, and items are being recycled or composted, but they are not supposed to be there, so they contaminate those collections.

Once the teams identify the items that ended up in the garbage, the following waste pyramid can be used to help determine how to address these items.

Let’s discuss how this pyramid applies to a plastic water bottle

  • In order to refuse, the team could encourage workers not to use a water bottle at all, but instead drink from the faucet or drinking fountain.
  • To reduce, the team could work to increase the amount of recycled content in the water bottles (fewer virgin materials), or order smaller sized bottles
  • Under the Reuse category, they could have workers bring their own reusable bottle to fill up at a refill station or water fountain, or use the plastic bottle they purchased more than once.
  • For the Recycle category, they could work on increasing the number of people who are recycling their plastic bottles through better signage, more recycling bins, or better education.
  • If you notice, recycling is way down the list. It’s a good thing to recycle, but we want to take actions to refuse, reduce and reuse before we have to recycle.
  • If the water bottle cannot or does not get recycled, there is one more option before it goes to the landfill. Some places are able to burn the bottle and recover the energy and use it for electricity. There are some negatives that can come along with this approach, but sometimes it’s better than the last step, which is to dispose, or throw away the bottle into the landfill.

Credit: The WASTE pyramid was provided by the Purdue Technical Assistance Program Green Manufacturing Specialist program at Green Manufacturing at Purdue TAP

Prior to conducting a dumpster dive, use this checklist to make sure you don’t forget something.

  • Sort bins and containers with signs on each, so it’s easy for the volunteers to read
  • Scales to weigh each container, which will be used for the summary report
  • Volunteers to sort through the trash
  • Experts for determining which items go into which container
  • Protective equipment in case there are sharp objects or dangerous items in the trash
  • Waiver forms for volunteers to sign
  • A large area or space identified where the trash can be laid out and sorted. It’s preferred to conduct the audit outdoors in a visible area so it attracts a crowd
  • Table covers so the trash doesn’t dirty the tables or floors
  • And finally drinks and refreshments for the volunteers

In order to maximize the effectiveness of the dumpster dive, here are some things to consider.

You should sample at least 10% of the total solid waste in the building or area. Anything less than that may lead to misleading results.

The collection should represent the entire building or area, so the results will be representative of the whole area. Again, only looking at certain areas and ignoring others will lead to misleading results.

You should have material experts available, to help evaluate and categorize the items being sorted. Each category will be evaluated to determine if it can be recycled or composted, so these experts will help greatly with this discussion. Your waste management or recycling advocacy groups can provide this expertise.

Remember, this activity can provide great opportunities to save money, not just help the environment. In fact, previous activities have identified up to 50% cost savings opportunities to landfill charges for items that were not being recycled, as many waste management companies charge less for recycling and composting than they do for trash.

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