1. Clark Elementary School Cafeteria Waste Audit
By Chris Bruno, Resource Conservation Manager
With help from Terry Hayes, Lead Custodian
Chris conducted an audit of the Clark Elementary School cafeteria on May 6, 2016, for commingled recycling, compost recycling, liquids, and trash. Terry saved all waste from the lunches weighing 19, 40, 15, and 73 lb respectively. Based on this sample Clark has a current cafeteria recycling rate of about 50%.
Chris then sorted through the trash bags and found 63 lb of recyclable material. Therefore about 85% of the trash could have been recycled.
All recycling bags were also checked for contamination and from both the commingled and compost bags, about 14 lb of solids and 4 lb of liquids were found. This gives a recycling contamination rate of about 30%.
Thus from this sample size, Clark has a potential cafeteria recycling rate of about 90%, assuming all materials and liquids are placed in the proper receptacles.

2. Pre Sort: total weight 146 lb
commingled recycling
compost recycling
trash
8 bags of solid waste from two stations covering two lunches. The average weights for the commingled, compost, and trash bags were 9.3, 20, and 18.3 lb respectively. Liquids weighed about 15 lb but are not included in this picture.

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. About 85% of what went into the trash bags could have been recycled. The commingled recycling had a high amount of contamination but the contamination in the compost recycling, however, was relatively low.

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

5. Solid Waste Potential Composition by Weight
The Clark lunchroom recycling rate has the potential to be about 90% and each of the three categories of recycling has the potential to double if everything is properly sorted. Compost takes up about 2/3 of the waste stream so that category deserves the most attention.

6. Solid Waste Composition by Weight
Category
Weight (lb)
Commingled recycling
5.4
Commingled recycling (found
in trash bags)
6.5
Compost recycling 47
Compost recycling (found
45.4
Liquids
14.7
Liquids in trash/recycle bags
15.3
Actual trash (includes recycling contamination)
12.1
Total
146.4

7. Commingled Recycling
All material from the two recycling bags with the actual recyclable material on the right of the picture. The pile on the left should have gone to compost, and trash is seen in the center. Uneaten/untouched food is grouped at the bottom center.

8. Compost Recycling
All material from the two compost bags with the actual compostable material on the right of the picture. The pile on the left should have gone to recycling, and trash is seen in the center. Uneaten/untouched food is grouped at the bottom center. The plastic bag was mostly full of pre consumer compostable waste from the salad bar.

9. Trash Bags Sorted Compost recycling in trash: 45.4 lb
Commingled recycling
in trash: 6.5 lb
Actual trash: 9.7 lb
The trash bags were sorted to determine how much “actual” trash they contained. All untouched/unopened food is separated in this picture but was weighed as part of the “compost recycling in trash” category.

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