DNV takes a greener approach to roadwork

By District Staff on Tuesday, Dec 14, 2021

We’ve adopted innovative paving methods to reduce carbon emissions and help create a more sustainable road ahead.

In 2019, we began a pilot study using warm-mix asphalt and found that the new pavement technology reduced emissions without reducing paving quality.

Based on the trial’s success, we’ve switched to warm-mix asphalt for all contract paving projects, including new paving projects and the regular maintenance of roads.

Our public works department is responsible for maintaining nearly 900 kilometres of roadway and 190 kilometres of sidewalk to keep streets safe and accessible for cyclists, pedestrians, motorists, commercial vehicles and public transit.

“We have put a lot of effort into environmental initiatives and technologies in paving and construction over the past few years,” says Mike Clarke, section manager, Construction and Survey. “With Council’s direction to focus on combating climate change and adopting green initiatives, we were looking for how we could reduce our carbon footprint in construction.”

Climate leadership in operations  

Warm-mix asphalt (WMA) technology allows asphalt to be mixed and placed at lower temperatures than conventional hot-mix asphalt. With this reduced temperature, emissions and energy consumption are also reduced.

 “The District’s early adoption of warm-mix asphalt technology and its environmental leadership has been instrumental in convincing other municipalities to follow suit,” says Kevin Bowyer, technical supervisor at BA Blacktop, which produces WMA for the District and performs annual paving and road rehabilitation across the municipality.

In 2020, BA Blacktop supplied the District with 14,120 tonnes of WMA. With an average temperature decrease of 17.5°C, that equates to an estimated reduction of 43 metric tonnes of CO2.

The temperature reduction also reduces the emissions, fumes and odours at the plant and improves the working conditions for crews while paving.

Keeping materials out of the landfill

Recycled Asphalt Pavement (RAP) is created by taking road grindings from an existing road and then incorporating the material back into new asphalt. By incorporating RAP into new asphalt, the amount of virgin asphalt cement and aggregate that is required is reduced.

Currently, we use the industry standard of 15 percent RAP in its asphalt mix and we are testing a mix design of 30 percent RAP, which would further reduce the amount of old asphalt bound for the landfill. 

In addition to using recycled pavement in asphalt paving projects, we also recycle asphalt grindings milled up from existing roads for lane and road grading and the production of recycled construction aggregate (gravel).

Embedding climate action into decision-making and operations

In 2019, District Council declared a climate and ecological emergency and subsequently adopted a Community Energy and Emissions Plan with targets of a 45% reduction below 2007 emission levels by 2030, and net zero emissions by 2050.

“The DNV has a long history of integrating environmental considerations into operations, policies and programs,” says Caroline Jackson, manager, Climate Action, Natural Systems and Biodiversity.

“We are accelerating initiatives like this one across the organization to accelerate change and embed climate action into decision-making, including new corporate standards, climate and ecological reporting metrics.”

Learn more about how we are taking action to reduce carbon emissions and energy consumption

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