Sorting Challenge 2013/14

As part of our campaign to improve recycling rates at City, we have introduced the Sorting Challenge. The aim of the challenge is to see which department is on the ball when it comes to the disposing of their waste. Random, unannounced audits of bins in staff kitchens will be carried out over the next few months and each kitchen will be ranked based on how much contamination is found in each type of bin (General, Recycling and Food Waste).

Contamination for the leader board will be calculated as per the example below:


Audit form for Kitchen X

Bin Type Location (or Description of) Fill Level (%)* Contamination? If Yes, list contaminants Waste types and proportions (%): Must add up to 100 *Food waste bins only if there is contamination Calculation of contamination
General Waste   Kitchen 60% Yes, Plastics, paper, cans Recyclable plastics (30%)Paper (20%)Cans (30%)Crisp Packets (20%)

Assuming total volume = 60 then 30% of 60 = 18 

20% of 60 = 12

30% of 60 = 18


Total volume of contamination = 48

Co-mingled Recycling Bin Kitchen 80% No Paper, card (100%)  N/A
Food Waste Bin Kitchen 10% Yes, paper Food (90%)Paper (10%)  Assuming total volume = 10, then 10% of 10 =1Total volume of contamination = 1

*Volume of bin taken to be 100 units. Therefore, 1% = 1 arbitrary unit


Total volume of waste (arbitrary units) = 60+80+10 = 150

Total volume of contamination (arbitrary units) = 48 + 1 = 49

Total contamination expressed as a percentage of total waste = 49/150 = 32.7 (rounded up to 1 decimal point)

It is this figure that is used for the Leader Board

Past Leader boards can be found here: