Between the lines: overhead vs underground

The derecho that damaged our city’s electricity system in May was absolutely devastating to our community. That being said, we have been reading, and listening to our customers, and know that there are several questions surrounding infrastructure and underground wires. While buried lines may seem like an obvious fix based on the recent number of damaged poles resulting from the storm, the answer is much more complex. Let’s take a look at the different hurdles that come along with a project of this magnitude.

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Numbers for our customers

Making the switch to a full underground system would come at a hefty cost. Complete underground servicing costs residents roughly 11 times more than overhead infrastructure does. Per square kilometre, switching to underground lines costs anywhere between $2 million and $4 million. For a full scope look, burying the lines for the entire Hydro Ottawa territory would cost approximately $10 billion and take about 90 years to complete.

While some newer neighbourhoods already have this cost covered by developers and then worked into the price of the homes, the reality is that it would be a hefty bill for homeowners. While our focus is to always provide safe and reliable energy to our community, we always want to ensure that this energy is delivered at the most reasonable cost to our customers.

It should be noted that, if funded by others, and where feasible, Hydro Ottawa can bury wires provided it is consistent with the Conditions of Service and design guidelines. The City of Ottawa policy for the burial of overhead power lines remains as directed by City Council on April 13, 2011 “that the undergrounding of overhead wires on City right-of-ways be undertaken only when the full cost of burial is paid for by the requesting party, or as otherwise approved by Council on a case-by-case basis.”

Unwanted outages in our communities

When it comes to the idea of burying hydro lines, we want to be realistic and transparent with our customers. Both the strategic work to install a new underground system as well as repairs to that infrastructure are less than ideal for residents and generally come with lengthier downtimes compared to overhead systems. That is because any outages caused by underground equipment issues, whether planned or unplanned, require much more intricate work.

Even the smallest repair requires street excavation which inevitably leads to road closures, streetlight outages, traffic delays and more. This means that we would be inviting the same headaches associated with sporadic outages in overhead lines to everyday maintenance if we were to work with underground wires. Additionally, the proximity of underground lines to other utility infrastructure plays a large role in interruptions that occur with this type of groundwork, too. Lastly, and this is especially prominent in our river city, floods can be a major hit to buried lines.

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Resiliency rather than immunity

At Hydro Ottawa we recognize that a combination of different elements is what is best for our customers when hardening our infrastructure. On average, Hydro Ottawa customers had power 99.987 per cent of the time in 2021 (and 99.981 per cent in 2020). To achieve this, we use a mix of state of the art technology as well as innovative materials. While we do have 3,000 km of cable within our underground distribution in very high-density environments, our emphasis is also on cost effectiveness as well as sustainability. For instance, the wooden poles often used in our communities are cost-effective for consumers and highly recyclable for the environment. They also have a lifespan of roughly 40 years!

It should be noted that while wooden poles come with benefits, we recognize that certain areas require additional support to protect our infrastructure. This is done through composite poles, which can last up to twice as long as their previously mentioned counterparts. They also have a high strength-to-weight ratio, meaning they can be used in areas that may not be able to support a wooden pole (wet soils, ditches, swampy areas, or other structurally sensitive areas), and they are resistant to both rot and wildlife damage. Moreover, our composite poles are manufactured right here in Ontario.

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Tree trimming keeps everyone safe

In order to balance the benefits of a healthy tree canopy with the needs for public safety and electricity supply reliability, Hydro Ottawa conducts a Tree Trimming Program throughout the year.

Our tree trimming crews are trained in proper pruning techniques and do their best to redirect growth away from the power lines while attempting to protect the health of the tree. Every effort will be made to minimize the impact to the trees. Our experts evaluate the landscape around the electrical equipment and the natural structure of the tree before any work begins. The individual characteristics of each tree are also taken into consideration. To learn more about tree trimming and how it helps to keep you and our hydro lines safe, click here

We would like to thank our community for staying curious and wanting to know more about Hydro Ottawa’s infrastructure, so if you have any topics that you’d like more information on, please leave your feedback and we will consider them for future articles.

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