What happened to the green arena roof in Lansdowne 2.0?

Carolyn Mackenzie calls it the Great Toboggan Hill.

It's a grassy berm overlooking the Great Lawn at Lansdowne Park with a sweeping view of the end zone at TD Place. Mackenzie, chair of the Glebe Community Association's planning committee, will be sorry to see it go.

"The overriding concern is about the loss of green space, and the Great Lawn will be the not-so-great lawn anymore," she said.

That's because the plan for Lansdowne 2.0 would replace much of the Great Toboggan Hill with an arena and event centre. That might not have been so obvious at first glance, since previous aerial renderings of the site plan included a green roof looking just as grassy as the berm.

It wasn't meant to be publicly accessible, but the original proposal said it "aesthetically forms part of the berm that will tie the Event Centre in with the greenspace of the Great Lawn."

"I can't say that they ever pretended, although many people did come away with the idea that they would be able to walk around," Mackenzie said. "Let's just say I don't think the city went out of its way to be clear about the impact on the park."

Now even that semblance is gone, as the latest plan for Lansdowne 2.0, released Friday, quietly replaced the green roof with a white one. Even the before-and-after diagrams included a white roof for the 2022 version, as if the grassy dome had never existed.

Was it ever part of the plan?

Mayor Mark Sutcliffe told reporters the green roof was only ever meant to be an option, and it turned out to be an expensive one.

"It hasn't been removed," he said. "It wasn't a part of the 2.0 plan. It was something that city staff was asked to look at and it's very expensive. And there is a way to achieve environmental sustainability for the building… without using an expensive green roof."

But it actually was part of the plan from Ottawa Sports and Entertainment Group (OSEG), according to the group's vice president, Janice Barresi.

At least until now.

"We submitted a proposal with a green roof to the City of Ottawa and then council said, OK, we will approve this in concept, but we want the city to go away and do its due diligence," she said in an interview.

That due diligence led city staff to the conclusion that the green roof didn't work financially, she explained. They didn't include it in the revised concept plan they're recommending to a joint meeting of finance and planning committees, which are set to vote on the proposal next month.

"What we submitted was our thought process, but it's a city asset, so they get to decide," Barresi said.

Still, OSEG president and CEO Mark Goudie now shares some of the city's concerns.

"We worked with our architects in helping refine the plans for the event centre and it was their strong recommendation that we don't put a green roof in place," he said at the media conference that revealed the new design.

"Arenas will leak and finding the source of those leaks is very expensive, so it was going to be a much more expensive building to build, for sure, but also to maintain long term."

How much would it cost?

City staff studied three options for the green roof. One had a thin layer of soil suitable for only a limited range of plants. That would cost $4.2 million. An "intensive" green roof with thicker soils for "herbaceous perennials" and "ornamental grasses" would cost $7.2 million.

A third option would actually recreate the berm, in a sense, with a publicly accessible and removable roof with thick soils for a price tag of $28 million.

In a report released Friday, city staff found fault with all of those options. It said the cheaper ones wouldn't really integrate with the Great Lawn, and while they might provide some stormwater management advantages, better possibilities exist to make the site even more sustainable.

"There is an opportunity to explore a solar panel roofing system to generate electricity," the report said.

"Electricity generation through solar ensures local energy security and reliability and promotes economic competitiveness and resiliency."

What does it mean for sustainability?

Angela Keller-Herzog, executive director of Community Associations for Environmental Sustainability Ottawa, fears broader concerns about environmental sustainability are getting lost in debates about the roof, green or otherwise.

"It was already a half measure, because it wasn't green space that could be really used by the community and by the growing number of residents," she said. "So I was already dubious about this before."

She said the bigger environmental questions for Lansdowne are about walkability, liveability and transit access.

"I think the problem, in terms of lack of transit to the site — that persists," she said.

"There is not a commensurate investment in public transit."

While proponents of the plan have noted that it will be LEED certified (a rating system for green buildings), Keller-Herzog argued that's actually not an ambitious standard. The certification is required as a matter of course for all city buildings beyond a certain scale.

"This micro question of what's happened with this partially nice green roof ... which has now disappeared, that's one little element, but I think it's more useful to look at the overall building standard," she said. "LEED silver is a very old standard."

Sutcliffe said the new Lansdowne would be much more sustainable than the current north stands, which is "one of the most energy inefficient facilities in the entire city."