A Greener Approach To Collect And Clean Rainwater In Vancouver

The city of Vancouver, surrounded by waters on the west, north and south, is on the front line of climate change. The Intergovernmental Panel on Climate Change projects a rise in sea level of .5 metres by 2050 and of one metre by 2100. That increases the flood risk for thousands of people living in low lying areas of the city.

While those long-range forecasts may seem fanciful to some, we are already seeing the impact of extreme weather events in BC. The November 2021 atmospheric river was costly and devastating to many cities, towns and First Nation communities in the province. A group of scientists predicts such weather phenomena will occur more frequently in BC because of climate change.

A report from the city of Vancouver states, “More extreme rainfall events in fall, winter and spring are to be expected by 2050. Specifically, there is an expected increase of 12% in fall, 5% in winter and 7% in spring precipitation. The amount of rain from each of these events is also predicted to increase, with 33% more precipitation on very wet days and 63% more on extremely wet days.” Those rain periods will also be punctuated by drier summers.

Heavy rain has overwhelmed the Vancouver sewer and drainage system causing localized flooding and resulting in another problem, contaminated water flowing into Burrard Inlet, False Creek, Fraser River and the Salish Sea. That’s because the underground network of combined sewer pipes moves both rainwater runoff and sewage in the same pipes. When rainwater hits hard surfaces like streets and roads, it picks up all kinds of contaminants that flow into the drainage system.

Damaged Stanley Park seawall after atmospheric river, 2021. Photo: Bill Stovin.

In response, the city of Vancouver has developed a series of plans including the ‘Rain City Strategy’ which City Council adopted in 2019. Its objectives include removing pollutants from water and air, reducing the volume of rainwater entering the pipe system, and harvesting and reusing water. Project director, Jennifer Bailey, describes it as a transformative direction.

“It really speaks to rainwater being a resource, not a waste product. What we have always done in the past was to get rid of it as quick as possible. Now there is an understanding that we can capture and treat it or reuse it. So letting it just flow into a receiving body is not a practice that is good for the environment.”

Jericho Beach, 2022. Photo: Bill Stovin

Replacing Vancouver’s aging underground sewer and drainage system presents a major challenge. The city knows that many of these pipes built in the early to mid-1900s, and during major city densification in the 1960s, are reaching the end of their life and need to be replaced.

Bailey acknowledges it is a costly situation.

”It’s very expensive to do these systems and we have deteriorating assets. We have been polluting the environment in a way that is not acceptable with our combined sewer overflows. So we need to get in front of that as well, plus we have a growing population. We are pulling together our data to see where we can make the best impact. So, how do we do this in an affordable way?”

The city has been replacing combined pipes with separated pipes since the 1970s and for over 10 years it has been ramping up nature based initiatives , so called ‘green rainwater infrastructure (GRI),’using soil and plants, and built structures such as swales, rainwater tree trenches and rain gardens to capture and treat rainwater closer to where it falls.

Under the Rain City Strategy, the city’s target is to capture and clean a minimum of 90 percent of Vancouver’s average annual rainfall long term; and to manage urban rainwater runoff from 40 percent of impervious areas in the city by 2050.

The city believes it’s a more cost effective and environmentally sound approach.

“A combination of nature-based and traditional engineered systems is where you will get your best value. That’s where we’re going to get the best bang for the buck. It’s the best value to optimize for what we already have and research for where you put your green rainwater infrastructure,” adds Bailey.

Since the adoption of the Rain City Strategy the city reports 65 new GRI assets built in the public realm, and 93 new GRI assets in the private realm with approved building permits. Some project highlights can be found here.

They include an eight block stretch of Richards Street downtown where a tree trench was built underneath a bike lane. It collects and cleans polluted rainwater from streets and sidewalks while providing shade, helping to mitigate the effects of an urban heat island.

At Yukon street and 63rd Avenue, a newly constructed bioswale is helping to filter out pollutants before the runoff reaches an overflow catch basin.

Another GRI project has been built in Sunset Park where the community was experiencing localized flooding. The creation of a bioswale is filtering the runoff while the planting of trees has provided a shady canopy and improved habitat for birds.

The city’s water management efforts particularly in False Creek are being watched closely by Zaida Schneider. After retiring as a journalist, Schneider spent 12 years cruising the waters off the coasts of California and Mexico before returning to Vancouver in 2018.

“I was flabbergasted about how much indifference there was to the marine environment, especially in False Creek. The seawalls were pretty, the high rises were gorgeous but the water was like an afterthought.”

And so began conversations with other people including environmentalist Tim Bray about the quality of water and the idea of turning False Creek into Canada’s first urban marine park. Before long the two had co-founded Friends of False Creek with a mission to restore the False Creek marine environment in alignment with First Nations stewardship values and marine science.

“When you tell people the idea they get it real quick. We were the first to say what do you think about turning False Creek into something that Vancouverites can come to revere and be proud of?”

The False Creek Friends have been inspired by Europe’s first marine park at Plymouth Sound in the United Kingdom and have forged several partnerships with scientific, education and community groups. One of their most ambitious ventures has been the staging of a “bio blitz” in 2022, a survey of biodiversity life of the seafloor, water and shorelines of False Creek.

An interim report on the Bio Blitz has been released.

“A lot of people thought that False Creek was a dead zone but they were blown away by myriad life worthy of protection,” says Schneider.

It will be another month or so before the DNA analysis of water samples is complete and a final report produced.

Schneider is supportive of the Rain City Strategy but wants a quicker resolution to sewage tainted rainwater flowing into False Creek and other bodies of water.

“The city has a big plan to ameliorate that but it’s going very slow and it’s been frustrated by the fact that sea level rise will make the problem even worse.”

For its part, the city says it’s making progress in addressing the problem through green infrastructure and other measures. Rain City Strategy’s Jennifer Bailey says actions in the plan will probably get reprioritized as more data is collected.

“We do have to go to council every three years. So it’s overdue. We have a memo going to city council very soon. That will give a progress update.”

In other moves, city council in February 2023 approved the development of the Healthy Waters Plan to guide the city’s policies and investments in managing a wide range of issues. In the first phase of the plan, council has approved investments in sewer and drainage systems amounting to $656 million over the next four years, a 70% increase in expenditures.

Major spending decisions will need to be made in the future as costs will run into the billions of dollars over the coming decades. As noted in this memorandum to city council last year, 100% sewer separation by 2050 is not likely affordable or achievable. The plan will need to evaluate to what degree green rainwater infrastructure can contribute towards the objective of eliminating combined sewer overflows.

As for the challenges ahead for the Friends of False Creek, Schneider has this to say.

“Our strategy is to get as many people involved in the conversation and by offering community science projects so people can develop this sense of place and regard for this slender sliver of the Salish Sea. So far this has been a very successful approach.”

Bill Stovin is a retired journalist with a long career at CBC-TV and radio and in private radio as well as a former Communications Director in government.