Circularity in Public works

In public works projects, enhancing circularity can generate environmental and economic benefits. Scope 3 Consulting worked with a medium-sized city in the Pacific Northwest to quantify the environmental implications of their efforts to enhance the circularity of their operations.

We modeled two different projects: One was a river dike and park enhancement project. The other was road paving with high recycled content. In both cases, we found substantial reductions in climate impact (and other indicators as well) with enhanced circularity, compared to a business-as-usual scenario.

By reusing material on-site, the dike enhancement project avoided 1,000 tonne-km of dump truck operation, and saved 20 kt CO2e. In this project, dump truck transport was the largest single contributor, so it was important to have a realistic model of a dump truck. However, a specific dump truck model was not available. So, we customized a tractor-trailer truck model to have fuel consumption on par with heavy-duty dump trucks. In addition, we included the additional on-site material handling that was required for this circularity enhancement. The more complete model very slightly increased emissions, but improved confidence and vanquished any concerns about greenwashing.

By incorporating 30% recycled content in pavement, 100 kt CO2e were saved in their pilot project. When scaled to all applicable roads in the city, the impact could be over one Mt CO2e. For this project, we incorporated the high-quality pavement models developed by Michigan State University and Athena and YY ZZ. These were customized to use the specific mix of binders, aggregate, recycled content, and additives that were required.