Green Bin Audit Report 2015 Understanding contamination in curbside organics collection
Contents Executive Summary... 3 Audit 2015... 4 Background... 4 How Organic Waste is collected... 4 Education... 5 Inspection of green bins... 5 Audit findings... 6 Number of Contaminated bins... 6 Contamination by weight... 8 Contamination by volume... 8 Types of liners used... 8 Discussion... 9 Causes of contamination... 9 Small food related items... 9 Plastic bags... 9 Food in packaging... 10 Confusing items... 10 The use of compostable bags... 10 Conclusion and Next Steps... 10 Lessons for the future... 11 References... 11 Raw data... 12
Executive Summary The City of Nanaimo began to collect household organic waste in 2011. Organic waste is collected weekly with the separation of organics from garbage leading to a 50% reduction (by weight) in waste sent to landfill. The City of Nanaimo has invested considerable efforts into educating residents as to the proper separation and disposal of household organics. The 2015 audit aims to understand the efficacy of these efforts and to assess the level and type of contamination within the residential organic waste stream. 50 green bins from across the City of Nanaimo were audited. The audit found that 24% of the bins contained some type of contamination. The types of contamination can be categorised as follows: i. Small food related items ii. Plastic bags iii. Food in packaging iv. Confusing items Whilst a 24% contamination rate is less than desirable the actual amount of contamination compared to complaint materials is very small. The audit found that less than 1% of the weight and less than 1% of the volume of the material audited comprised of contaminants. The audit also found that 86% of residents line their green bin, with 82% of residents opting to use specially purchased compostable liners. A further 4% of bins were lined with paper. The following areas where further resident education is required have been identified: i. Increased vigilance when disposing of small food related items ii. The need to use compostable bags, not biodegradable bags iii. Increased vigilance when disposing of pre-packaged food iv. Clarification on certain confusing household items
Kg/household Audit 2015 The aim of the audit was to understand the level and type of contamination in the curbside organic waste collection with a means to assessing the effectiveness of the City s education program. Background How Organic Waste is collected Residential organic waste is collected by City refuse collectors. The City services single family dwellings and residences up to fourplexes in size. There are a small number of small businesses who also receive the service (those too small to arrange commercial pick up). In total; 26,698 households and 171 businesses receive curbside collection of organic waste (as of July 2015). Organic waste is collected weekly in 34 litre Orbis wheeled bins, known as Green Bins. The waste is manually loaded in to side loading garbage trucks. Upon completion of the route the waste is taken to Nanaimo Organic Waste, 981 Maughan Road, Nanaimo. Organic waste is banned from residential garbage and since implementation of the program in 2011 the amount of garbage collected at the curb has dropped by 50%. 500 450 400 350 300 250 200 150 100 50 0 2007 2008 2009 2010 2011 2012 2013 2014 Kitchen Waste Recycling Garbage
Education Over the years immediately preceding and following implementation of the Green Bin program residents have been constantly educated as to the requirements of the program. Examples of such education include: 1. Green Bin user Guide, first issued in 2011 to all households and updated in 2013. 2. Green Bin How to video, released in 2011. 3. Beyond Composting Website, originally launched in 2011. 4. Green bins coming, Wasteline Fall 2011. 5. How to care for your green bin, Wasteline Spring 2012. 6. Summer Tips for your Green, released in 2012. 7. On the path to a sustainable City, Wasteline Fall 2012. 8. Food Waste collection, Wasteline Spring 2013. 9. Curbside Green bin Guide, Wasteline Spring 2014. 10. Why did we tag your can?, Trash Talk, Spring 2015 In addition to the above, refuse collectors take the time to educate residents at the curb. Where a refuse collector notices a non-complaint green bin they will knock at the door (where safe and accessible) to see if the resident is home for a friendly chat, if nobody is home collectors leave reminder stickers and handouts. The box at the bottom of the sticker is used to give details of the non-compliant material. Inspection of green bins The manual nature of organic waste collection in the City allows for cursory inspection of every bin collected. Typically, a refuse collector will remove large items of contamination from the bin to allow collection of compliant material. However, where the refuse collector has made multiple attempts to educate the resident the bin and its contents will be left behind. This means that any large items of contamination are spotted and eliminated from the waste stream. Any items that are too small for the refuse collector to notice should be screened out at the organics processing plant. Refuse collectors typically site that the main item of contamination within the waste stream is plastic bags used to contain compliant material. Often these bags feature printing that describes them as biodegradable. Residents can be unaware of the distinction between biodegradable and compostable bags. Considerable focus has been given to the need to use only compostable liners featuring the certified compostable logo.
Audit findings The Audit took place over three days in July 2015. A random sample of 50 bins was audited. The contents of the bins were weighed and sorted. Items of contamination were recorded, photographed, weighed and their volume as a percentage of the contents was estimated. The type of any liner used (if any) was also recorded. Number of Contaminated bins Of the 50 bins audited, 12 (24%) contained items of contamination. Of the 12 contaminated bins, one was contaminated obviously enough that the non-complaint material would have been spotted by a refuse collector. The other items of contamination were hidden within compliant organic material or contained within tied compostable bags. Details of contamination found in the 12 bins containing non-complaint material 1 1/2 a bread clip & Top off a juice box 2 Plastic sausage skin 3 Cheese string in packaging and yogurt tube 4 6 Plastic bags containing compliant compost (contained in compostable liner). 5 Q tip and candy wrapper 6 Filter material 7 Metal twist tie 8 Foil lined cardboard lid 9 Plastic straw wrapper 10 3 Metal twist ties 11 3 plastic bags 12 Pop bottle cap
Examples of Contamination found during audit
Contamination by weight The total contents of the audited bins weighed 291.50 kgs. The average weight of as single green bins contents was 5.8 kgs. The total weight of the contaminants found was negligible at 33g (0.01%). The weight of contaminants had to be estimated as the items were too light to register on the digital scale. Contamination by volume It was estimated that the contamination within the bins represented 0.1% of the total volume of the bin contents. For this reason, with the exception of plastic bags, the contaminants encountered during the audit would be particularly difficult for refuse collectors to spot. Types of liners used 41 (82%) of the bins audited were lined using specially purchased starch based compostable liners. A further two (4%) bins were lined with paper; one specially purchased paper lined and one newspaper lined. Seven (14%) bins were unlined.
Discussion Although the sample size only represents a small selection of the City s households (0.2%), this sample can be considered representative of the City since 18 of the City s 35 routes were audited with an even distribution over the city. The audit sample included the full spectrum of dwelling types and socioeconomic areas that the City services. Levels of contamination appeared uniform across the City with no area out performing another. Causes of contamination The audit showed that it is unlikely that residents are actively attempting to hide non-compliant material within their organic waste. Rather there are specific reasons why the organics stream becomes contaminated. The findings of the audit imply the following lead causes of contamination to the organic waste stream: i. Small food related items ii. Plastic bags iii. Food in packaging iv. Confusing items Small food related items Six (50%) of the 12 contaminated bins contained small plastic food related contaminants that residents typically are aware are not compostable. This suggests that items find their way into the organics bin through oversight rather than misinterpretation of the guidelines. Plastic bags In two instances we found that residents had used plastic bags to contain otherwise compliant material. In the first instance the plastic bags were contained within a compostable bag. The plastic bags were clear with green writing indicating that they were biodegradable. It is likely that the resident had been confused by this distinction. In the second of these instances the auditor was able to speak with the homeowner about the use of plastic bags, the homeowner did not speak English and the auditor felt that he was unable to communicate effectively with the homeowner.
Food in packaging Food still in packaging accounted for two of the contaminated bins. Items were a sausage in plastic skin and individually wrapped cheese strings and yogurt tubes. It is likely that these items were placed in the bin from oversight since residents are generally aware that plastic wrapping is not compostable. Confusing items Two bins were contaminated with items that residents could be mistaken in believing are compostable. These were a foil lined lid from a take away food container and a piece of cotton type filter material. The use of compostable bags 82% of the bins audited were lined using specially purchased compostable liners made from plant starch. With average prices around 20c a bag this represents a considerable commitment by residents to source and use the correct liners for the purpose of keeping their kitchen catcher and green bins clean (the cost of compostable bags to each residence is estimated at 60c a week or $31.20 a year, (Region of York, 2011)). Compostable bags are available at most grocery and hardware shops in the City; the high usage of these bags is testament to the City s efforts to educate residents to look for the compostable logo. There is certainly further work to be done in terms of educating all residents about the need to use compostable bags over biodegradable. Based on audit results it could be considered that 5% of the City s residents are confused about this distinction. Furthermore, it could be considered that residents who speak English as a second language may not understand the educational materials provided. The use of paper bags was low compared to starch bags with only 2% of the sample bins featuring specially purchased paper liners. Paper liners are more expensive than starch liners with the average cost being 55c per bag ($1.65 per week or $85.80 per year per household, (Region of York, 2011)). 16% of residents opted to either not line their green bin or to use newspaper as a free alternative to a specially purchased liner. Conclusion and Next Steps At first glance, the contamination rate of 24% is alarming, however, upon closer inspection of the types, weight and volume of this contamination the situation is not so dire with less than 1% of the weight and volume of organics audited comprising of contaminants. Doubtless the ability of our refuse collectors to manually inspect the green bin further safeguards against contamination however, the lion share of contamination is not noticeable without ripping open bags and closely inspecting the contents. This finding is favourable since the City is considering a move
to automation which would remove our ability to manually inspect each can. With an automated system there will be cameras in the truck hopper to allow refuse collectors identify and remove large items of contamination. Lessons for the future The audit has pinpointed areas of focus for future education of residents, in order of priority these are: v. Increased vigilance when disposing of small food related items like bread clips vi. The need to use compostable bags, not biodegradable bags vii. Increased vigilance when disposing of food (remove packaging) viii. Clearing up confusion around certain items like cotton and foil-lined card References Region of York, 2011. Compostable bag retail price list. https://www.richmondhill.ca/documents/compostable_bag_retail_price_list.pdf
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