1. Issaquah High School Cafeteria Waste Audit
By Chris Bruno, Resource Conservation Manager
With help from Craig Abbey
Chris conducted an audit of the Issaquah High School cafeteria on January 9, 2016, for commingled recycling, compost recycling, and trash. Craig collected all waste from the lunches giving a sample size of 12 bags of commingled, 18 of compost, and 12 of trash, weighing 49, 65, and 104 lb respectively. Based on this sample Issaquah High has a current cafeteria recycling rate of about 50%.
Chris then sorted through the garbage bags and found 10 lb of commingled material, 68 lb of compostable material, and 10 lb of liquids. Therefore, about 84% of the garbage could have been recycled.
The recycle bags were also sorted. The commingled bags had 9 lb of contamination and 13 lb of liquids. The compost bags had 8 lb of contamination and 1lb of liquids. Therefore, the recycling contamination was about 14%.
Thus from this sample size, Issaquah High has a potential cafeteria recycling rate of about 80%, assuming all materials are placed in the proper receptacles.

2. Sample Size: 218 lb commingled recycling compost recycling trash
42 bags of solid waste from six stations covering all lunches.

3. Solid Waste Current Composition by Weight
With a small sample of just one day, the recycling rates should be estimated to one significant figure only. The left pie chart shows the data from simply weighing the trash/recycle bags, and the right one is a more in-depth look at what was found in the bags. Liquids overall were about 10% by weight. Over half the weight of the commingled recycling was contamination, but that is typical in most schools. The compost recycling had no liquids and very little contamination.

4. compost recycling contamination commingled recycling contamination
Post Sort
compost recycling
Commingled in trash
commingled recycling
compost in trash
Actual trash
compost recycling contamination
commingled recycling contamination
This picture shows the compost and commingled recycling with contamination on the bottom, and the trash bags sorted at the right. Liquids from the recycling and trash bags are not shown in this picture.

5. Solid Waste Composition by Weight
Category
Weight (lb)
Recycling commingled
27.2
Recycling commingled (found
in trash bags) 10
Recycling compost
57.2
Recycling compost (found
67.8
Actual trash
16.4
Recycling contamination (goes to trash)
16.2
Liquids in trash/commingled bags (should go in trash)
22.8
Total
217.6

6. Solid Waste Potential Composition by Weight
Since it’s not practical to have liquid collection buckets in Issaquah High’s cafeteria, the “potential rate” assumes that all liquids are poured into trash bins. If liquids could somehow be separated then the potential rate jumps to 90%.
The best opportunity for improvement comes from diverting compost out of the trash. This audit found over half of all compostable material being discarded into trash bins.

7. Commingled Recycling
All material from the 12 recycling bags with the actual recyclables at the top and contamination separated out at the bottom. The liquids can be seen in the green bucket, with most coming from a few water bottles that were mostly full.

8. Compost Recycling
All 18 bags of compost recycling with contamination separated at the bottom of the picture.

9. Trash Bags Sorted commingled recycling in trash: 10 lb
compost recycling
in trash: 67.8 lb
actual trash: 10.3 lb
The trash bags were sorted to determine how much “actual” trash they contained. Approximating by volume the three categories are about equal, but by weight the recyclable material is 84%.

10. extra pictures available on connect.issaquah.wednet.edu
To find more pictures, a pdf report, and a PowerPoint slide show, go to Connect:
Intranet
Operations Department
Resource Conservation
Waste Audits