Food Diversion Cart Tag Study - Waste Management Northwestwmnorthwest.com/20XXsummary/fyw/materials/Cart Tag Pilot... · 2018-02-25 · Food Diversion Cart Tag Study Final Analysis

King County Food Diversion

Cart Tag Study

Final Analysis Summary

Prepared by Cascadia Consulting Group

for King County Solid Waste Division

May 18, 2017

Study Team

Study Questions

▶ Do cart tag prompts increase residential

participation in food scrap diversion?

▶ Which (if either) tagging frequency supports

sustained behavior change?

▶ Do cart tags have different effects under

different service arrangements?

Tag Designs

Service Arrangements across Study Areas

Kenmore

North KC

Burien

Subscription service

Universal organics service

Weekly collection

EOW collection

Study Timeline

Kenmore Burien North KC

Audit – Baseline Nov 2015 March 2016 March 2016

Tagging – Round 1 (T2, T4)

Dec 2015 Apr 2016 Apr 2016

Tagging – Round 2(T4)

March 2016 July 2016 July 2016

Audit – Midpoint July 2016 Sep 2016 Sep 2016

Tagging – Round 3(T2, T4)

July 2016 Oct 2016 Oct 2016

Tagging – Round 4(T4)

Oct 2016 Jan 2017 Jan 2017

Audit – Final Nov 2016 March 2017 March 2017 *T2 HHs were assigned to receive tags biannually; T4 HHs were assigned to receive tags quarterly.

Audit Methodology

▶ Collected contents of paired HH garbage,

organics cart set-outs

▶ Random interval sampling

▶ 150 households sampled per study area

(plus contingency, even split T2/T4)

▶ Samples represent 7% of HHs with organics

service in study area

▶ 5 material list, only food capture calculated

▶ Error range for avg. food capture rates

<+/-10% at 90% confidence

Material Sort List:

1. Food

2. Compostable Paper,

Plastic, and Food-

Related Wood

3. Non-Compostable

Paper and Plastic

Food Service Items

and Packaging

4. Yard Debris

5. Other Material

Final Analysis

Findings

Tagging Implementation

Study

Area

# T2 HHs

in study

Not

Tagged

Tagged

1x

Tagged

2x

# T4 HHs

in study

Not

Tagged

Tagged

1x

Tagged

2x

Tagged

3x

Tagged

4x

Kenmore 695 7% 25% 68% 680 1% 10% 21% 37% 32%

Burien 1,542 11% 34% 55% 1,538 3% 8% 19% 33% 37%

North KC 1,219 4% 28% 68% 1,267 2% 5% 14% 35% 43%

TOTAL 3,456 8% 30% 62% 3,485 2% 7% 18% 34% 38%

▶ Not all households were tagged – only those with carts set out on day of tagging event.

▶ Only 62% of T2 assigned households actually received two tags.

▶ Only 38% of T4 assigned households actually received four tags.

Food Scrap Diversion Behavior - Participation

▶ Significant increase in

HH participation in

food scrap diversion in

Kenmore & North KC.

▶ Participation in Burien

was very high from the

start. Increased among

T4 households but not

statistically significant.

▶ Higher participation

from T4 HHs across all

study areas, but not


Study Area Baseline

Participation Rate

Final

Participation Rate

T2 HHs (%) T4 HHs (%) T2 HHs (%) T4 HHs (%)

Kenmore 50% 44% 62% 68%

Burien 77% 78% 77% 85%

North KC 61% 58% 71% 74%

Food Scrap Diversion Behavior - Efficiency

▶ Over study period,

more HHs started

participating in food

scraps diversion and

existing participants

diverted more of

what they generated.

▶ Overall, the percent

of HHs diverting

<20% of food scraps

fell from 43% to 30%.

43%

5% 7% 9%

35%

0

50

100

150

200

0-20 20-40 40-60 60-80 80-100

Ho

use

ho

lds

Food Capture Rate(baseline)

30%

7% 9%14%

40%

0

50

100

150

200

0-20 20-40 40-60 60-80 80-100

Food Capture Rate(final)

Overall HH food scrap diversion efficiency distribution


▶ Kenmore experienced

significant jump in

participation.

▶ The percent of HHs

diverting <20% of

food scraps fell from

59% to 41%.

▶ Diversion efficiency

of new participating

HHs was lower than

experienced HHs but

increased over time.

59%

3% 4% 6%

28%

0

20

40

60

80

100

0-20 20-40 40-60 60-80 80-100

Ho

use

ho

lds


41%

9% 12%8%

31%

0

20

40

60

80

100

0-20 20-40 40-60 60-80 80-100


Kenmore HH food scrap diversion efficiency distribution


▶ In Burien, food scrap

diversion efficiency

was high from the

start but still

improved over time.

▶ By the end of the

study period, half of

all households were

diverting more than

80% of all food

scraps generated.

25%

5%11% 12%

48%

0

20

40

60

80

100

0-20 20-40 40-60 60-80 80-100

Ho

use

ho

lds


20%

7% 7%16%

50%

0

20

40

60

80

100

0-20 20-40 40-60 60-80 80-100


Burien HH food scrap diversion efficiency distribution


▶ In North KC, food

scrap diversion

efficiency distribution

shifted significantly

toward higher rates.

▶ Over study period,

more households

started diverting food

scraps and existing

participants diverted

more food scraps.

45%

9% 8% 10%

29%

0

20

40

60

80

100

0-20 20-40 40-60 60-80 80-100

Ho

use

ho

lds


30%

5%9%

17%

38%

0

20

40

60

80

100

0-20 20-40 40-60 60-80 80-100


North KC HH food scrap diversion efficiency distribution

Food Capture Rates – All HH Set-Outs

▶ Overall, average food

capture rates increased

by 20% (9 % points).

▶ Kenmore average food


by 22% (8 % points).

▶ Burien average food


by 8% (4 % points).*

▶ North KC average food


by 37% (15 % points).

45%35%

61%

40%

54%

43%

65%55%

0%

20%

40%

60%

80%

100%

Overall Kenmore Burien North KC

Perc

ent

of

Foo

d C

aptu

red

Baseline Final

Avg. food capture rates among all HHs with paired set-outs

2014 KC = 39.5%

*Change not statistically significant

Food Capture Rates – Participating HHs

▶ Overall, average food

capture rates among

participating HHs did

not change even

though the number

of participating HHs

increased.

▶ Small changes

observed among

participating HHs within

Kenmore and North KC

study areas are not


Avg. food capture rates among HHs participating in food scraps diversion

2014 KC = 66.6%

73% 74%78%

66%73%

65%

78%72%

0%

20%

40%

60%

80%

100%


Perc

ent

of

Foo

d C

aptu

red

Baseline Final

Organics Contamination Rates - Overall

▶ Overall, organics

contamination rates

increased slightly but

changes are not


▶ In Burien and North KC,

organics from

participating HHs had

higher contamination

than non-participating

HHs at final audit but

differences are not


Overall Organics Contamination Rates

2.0%

0.8%

3.0%

2.4%2.3%

1.1%

2.6%

3.4%

2.1%

0.9% 1.0%

5.2%

2.9%

0.8%

3.3%

5.0%

0.0%

1.0%

2.0%

3.0%

4.0%

5.0%

6.0%


Perc

ent

of

Org

anic

s C

olle

cted

Baseline (all set-outs) Final (all set-outs)

Baseline (participating HHs) Final (participating HHs)

2014 KC = 2.4%

Organics Contamination – HH Behavior

▶ Although changes in

contamination rates

were not significant,

the number of HHs


diversion with >5%

contamination

increased sharply.

▶ At final audit, 1 in 5

participating HHs had

>5% contamination

in organics carts.

Participating HH contamination rate distribution

69%

10%3% 3% 2%

12%

0

50

100

150

200

250

<1% 1%-2% 2%-3% 3%-4% 4%-5% >5%

Ho

use

ho

lds

Contamination Rate(baseline)

63%

7% 6% 3% 1%

20%

0

50

100

150

200

250

300

<1% 1%-2% 2%-3% 3%-4% 4%-5% >5%

Contamination Rate(final)

Food Scrap Generation – HH Behavior

▶ Across all study audits,

food scrap generation

was higher among HHs


diversion compared to

non-participating

households.

▶ Less food scraps among

non-participating HHs

may indicate underlying

demographic differences

(e.g. HH size, age, etc.).

2014 KC avg. = 49.1 lbs/hh/mo

31.8

40.035.2

48.7 49.652.9

0.0

10.0

20.0

30.0

40.0

50.0

60.0

Baseline Midpoint Final

Lbs

Foo

d G

ener

ated

Per

Mo

nth

Non-participating HHs Participating HHs

Avg. HH Food Scrap Generation Rates

Study Questions & Answers

▶ Do cart tag prompts increase residential food

scrap diversion? YES!

▶ Which (if either) tagging frequency supports

sustained behavior change? BOTH!

▶ Do cart tags have different effects under

different service arrangements? Bigger impact

in areas with lower participation at the start.

Final Takeaways

▶ Participation is (still) highest where organics service is universal and weekly.

▶ Increasing food diversion requires “activating” new households. (i.e. get households not currently diverting food scraps to start participating.)

▶ Cart tag “prompts” can activate new households to participate in food

diversion and also increase diversion from households already participating.

▶ Cart tag “prompts” effects increased with repetition.

▶ Increased food diversion may lead to higher contamination.

▶ Households that generate less food waste may be less likely to participate in

food diversion.

Lessons Learned

1) Cart-based audits can cause a stir…

‒ Field crew must be professional, well prepared

‒ Successful de-escalation requires all hands

(field crew, customer service staff, project managers)

…but the data gathered is valuable.

‒ Only way to assess household-level behavior

‒ Can improve program targeting, cost-effectiveness

Lessons Learned

2) Cart tag placement is labor-intensive…

‒ 2-person team can tag 500-700 HHs in a day.

‒ Tagging staff must be professional, organized,

efficient, hardy, and comfortable with data tracking.

…but technology can create major efficiencies.

‒ Spotio app cut tag placement times by 20-30%.

Lessons Learned

3) Cart tags designed for

recyclability do not hold up

well in heavy rain.

‒ Tag placement should be done

during dry weeks or alternate

design should be considered.

Lessons Learned

4) Single cart tagging events

do not reach all households.

‒ Tag placement should be done

repeatedly, at regular intervals,

to ensure all households receive

information.

‒ Study outcomes represent

effects of 2x year tagging.

Outreach Recommendations

▶ Focus on starting the behavior; rather than ‘doing more’

▶ Tag cart to start behavior at least 2x/yr

▶ Keep tag message focused (audience testing needed)

1. Place food in yard waste cart

2. Keep out contaminates

▶ Focus on contamination message separately and in priority

Outreach Recommendations

▶ Use tagging as part of an integrated campaign to change social norms and overcome barriers

Strategy Tactics

Raise awareness that you can compost at curb • Traditional Media• Social media• Direct mail

Provide tools and education to make it easy • Through grassroots outreach – events, outreach, one-to-one

• If possible, at point of YW service signup or service level change

• Collect commitments

Prompt to start behavior or modify behavior (contamination) • Curbside cart tags• Collect commitments

Provide feedback • E-communications• Social media• Direct mail

Documents

Food Diversion Cart Tag Study - Waste Management Northwestwmnorthwest.com/20XXsummary/fyw/materials/Cart Tag Pilot... · 2018-02-25 · Food Diversion Cart Tag Study Final Analysis