1. Pine Lake Middle School Cafeteria Waste Audit
By Chris Bruno, Resource Conservation Manager
With help from Mike Cautard, Lead Custodian
Chris conducted an audit of the Pine Lake Middle School cafeteria on January 22, 2016, for commingled recycling, compost recycling, and trash. Mike saved all waste from the lunches weighing 27, 60, and 81lb respectively. Based on this sample Pine Lake has a current cafeteria recycling rate of about 50%.
Chris then sorted through the trash bags and found 44 lb of recyclable material. Therefore about 55% of the trash could have been recycled.
All recycling bags were also checked for contamination and from both the commingled and compost bags, only 3 lb of solids and 12 lb of liquids should have been discarded as trash. This gives a recycling contamination rate of about 15%.
Thus from this sample size, Pine Lake has a potential cafeteria recycling rate of about 70%, assuming all materials and liquids are placed in the proper receptacles.

2. Pre Sort: total weight 168 lb
commingled recycling
compost recycling
trash
18 bags of solid waste from six stations covering two lunches. The average weights for the commingled, compost, and trash bags were 4.5, 9.9, and 13.6 lb respectively.

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. The commingled recycling had high contamination but the compost recycling had essentially none. About 20% of the weight came from liquids. About half of the weight of the trash bags was compostable material.

4. commingled recycling contamination compost recycling contamination
Post Sort
actual trash
commingled recycling
compost recycling
compost in trash
commingled in trash
commingled recycling contamination
compost recycling contamination
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 Composition by Weight
Category
Weight (lb)
Commingled recycling
9.4
Commingled recycling (found
in trash bags)
6.6
Compost recycling
62.2
Compost recycling (found
37.8
Liquids in trash bags 22
Liquids in recycle bags
12.2
Actual trash (includes recycling contamination)
17.8
Total
168

6. Solid Waste Potential Composition by Weight
At Pine Lake students are instructed to pour liquids into trash bins. With this practice the maximum recycling rate is about 70%. If liquids can be diverted out of the trash, then Pine Lake could have a recycling rate of about 90%.

7. Commingled Recycling
All material from the six recycling bags with the actual recyclables at the top, contamination separated at the bottom, and liquids separated in the green bucket.

8. Compost Recycling
All material from the six compost bags with the actual compost at the top and contamination separated at the bottom. No liquids were found.

9. Trash Bags Sorted commingled recycling in trash: 6.6 lb
compost recycling
in trash: 37.8 lb
actual trash: 14.9 lb
Liquids: 22 lb
The trash bags were sorted to determine how much “actual” trash they contained.

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