Comparing Collection Policies: Cost and Diversion Impact

Post Date: July 17, 2020

In anticipation of the curbside collection contracts renewal, pending regulatory/policy change and the development of a 30-year Solid Waste Master Plan, the City of Ottawa retained Dillon Consulting Limited (Dillon) to complete a study and develop a curbside collection model. The model assisted the City in identifying the most cost-effective curbside waste collection system to help support increased waste diversion and reduce residential garbage, while also considering greenhouse gas impact, and cost of implementation.

The model was designed as a tool to assist staff in developing curbside collection options and/or new policies. It is based in Microsoft Excel.

Collection Options
Analysis Model

The different waste diversion policies that were considered in the model were:

  • Bag/container limits for garbage
  • Pay As You Throw
  • Clear bag program for garbage
  • Containerized garbage program
  • Mandatory participation in diversion programs
  • Material bans e.g., grass clippings, organics and recyclables in garbage

The collection options considered in the model were:

  • Status quo
  • Weekly co-collection of blue/black box
  • Status quo level of service with a 4-day collection week
  • 4 day collection week
  • Status quo with separate weekly leaf/yard waste collection
  • Separate bi-weekly leaf/yard waste collection
  • Weekly collection of recyclables and leaf/yard waste

The model requires input of household information, collection seasons/periods, materials collected, truck compartment and utilization parameters, collection factors, collection costs and waste tonnage breakdown by material type to establish a baseline scenario, which is then used to compare against several different collection and policy options. It can compare new collection and policy options against status quo parameters including costs, vehicles required for servicing, diversion rates, and greenhouse gas (GHG) impacts.

Modeling required resources and system performance

Designed for adaptability, the model will allow other Ontario municipalities to analyze their integrated waste collection system by revising the inputs to the model and waste collection program policy customizations. The model produces several estimated outputs, including:

  • Number of trucks required (per season, per collection stream);
  • Number of hours required to collect materials (per season, per collection stream);
  • Annual cost per household and per person ($);
  • Capture rate (kg/person);
  • Diversion rate (%); and
  • GHG impacts (tonnes CO2 equivalents per year).

Note that this study only looks at residential households that receive curbside collection and does not include bulk material collection.

Lessons learned in Ottawa

Key outcomes of the modelling exercise for Ottawa were:

  • Higher curbside collection costs are attributed to weekly co-collection of dual stream recyclables and leaf/yard waste over a four-day collection week due to the number of vehicles required.
  • The lowest collection costs are for the status quo, and separate weekly or bi-weekly leaf/yard waste collection due to a lower number of vehicles being required than the other scenarios. Separate bi-weekly leaf/yard waste collection may produce less CO2 equivalents per year than status quo for all policy scenarios modeled.
  • Weekly co-collection of blue/black box under a four-day collection week is likely to produce the most CO2 equivalents per year due to the number of vehicles required and hours collecting waste materials.
  • There appears to be a correlation between cost effectiveness and greenhouse gas emissions; higher costs are attributed to model runs that have the higher number of CO2 equivalents per year.
  • Enforcement is key.
Photo source: Ottawa.ca

Next Steps

The City of Ottawa will be using these results to inform a subsequent project that will create business cases for each of the Service Level Options (SLO). Additionally, over the next 24 months the City of Ottawa is preparing a Solid Waste Master Plan. The results of these projects will be used in conjunction with other studies to determine the best path forward for Ottawa’s municipal waste programs.

For more information contact CIF staff or Lori Andrews at Dillon Consulting Limited.

Additional guidance can be found in the Technical Memorandum Synopsis: Integrated Curbside Waste Collection Model Development.