Director of Engineering Services Ryan O’Grady at Courtenay City Hall   |  Photo by George Le Masurier

Stormwater systems shift slowly toward green infrastructure

by Dec 19, 2018Environment, Stormwater2 comments

By George Le Masurier

This is the fourth in a series exploring the adverse effects on our waterways from how municipalities have traditionally managed stormwater runoff, and the slow shift to mimic natural through green infrastructure. This week we look at how Comox Valley municipalities are addressing the issues. Next week: what other communities are doing.

 

Stormwater management plans in the Comox Valley have historically treated rainwater as waste, something to be collected and disposed of quickly, usually into previously clean streams or directly into the ocean.

Our local governments have commonly relied on hard engineering solutions that employ expensive infrastructure, such as storm drains, catch basins, pipes and ponds.

That approach has removed and altered the source of groundwater that used to recharge our aquifers. And it has left us with polluted streams incapable of supporting aquatic life, shellfish harvesting bans, eroded private and public property, the loss of attractive natural environments and a long-term financial burden we cannot afford.

Shellfish bans to all of the K’omoks Estuary

Comox Valley governments already have more than roughly $400 million in unfunded infrastructure liabilities (even more if the calculation was based on replacement cost), and stormwater systems account for a significant portion of that staggering total. The Town of Comox alone had $160 million in 2012.

And each new regional housing development ultimately adds more to the total because builders pay development cost charges that cover only the costs of installing infrastructure. They pay nothing for ongoing repairs, maintenance and replacment. Taxpayers are saddled with that burden, forever.

Clearly, a new approach is needed.

Forward-thinking municipalities have shifted toward source control, managing rain where it falls through infiltration, evapotranspiration and rainwater harvesting, techniques known as green infrastructure. This improves water quality, reduces flooding and erosion and costs taxpayers less.

To fund this fundamental transformation in stormwater systems, some municipalities have introduced new fees based on the percentage of impervious surfaces on a property, along with corresponding financial incentives to install green infrastructure.

So, given the benefits and cost savings of going green, are Comox Valley municipalities and other local governments rushing to implement green infrastructure? Not exactly.

A 2017 study conducted by the Canadian Freshwater Alliance and Green Communities Canada, which included data from the Comox Valley, found that most municipalities were moving slowly.

“Most communities surveyed are not far advanced in adapting urban landscapes to manage rain where it falls,” according to a Green Communities summary of the study. “Communities appear to be making moderate commitments … in community plans.”

So, what exactly are Comox Valley municipalities doing?

City of Courtenay

Ryan O’Grady, the city’s director of engineering services, will lead the development of an Integrated Stormwater Management Plan (ISMP) in 2019. The plan will encompass strategies for flood mitigation in the downtown core, how to replace traditional engineered infrastructure with green solutions and will, he says, look through a broad lens at regional solutions.

“The ISMP will have an educational component, too, about stormwater systems,” O’Grady told Decafnation. “These will be challenging conversations, but there is a collective desire to change.”

Water and sewer issues have gotten most of every municipalities’ attention up until now, he said. Stormwater is one of the last service areas to focus on.

Rain gardens on Courtenay’s new ‘complete’ Fifth Street

“Our city has prioritized stormwater lower in the past to deal with drinking water,” O’Grady said. “All staff are looking forward to working on stormwater.”

The city has also shifted its approach to management of assets from reactive to proactive, a move he said came from Chief Administrative Officer David Allen (see separate story).

For example, the city is currently doing a culvert assessment where streams pass under roadways to see they are working properly. Good working culverts are important for fish passage. And the recently renovated upper portion of Fifth Street was designed with rain gardens to test how well they work and the ongoing cost to maintain them.

“We’re learning how to integrate green infrastructure and low-impact development going forward,” he said.

O’Grady intends for the stormwater plan to take a regional view, including discussions about Brooklyn Creek, which originates in Courtenay, flows through regional Area B and empties into Comox Bay.

“There’s a collective desire to collaborate … it would be great to work together,” he said.

The stormwater management plan project is part of a national pilot project to improve Courtenay’s resilience to climate change. The city is one of 72 across Canada chosen to participate.

O’Grady told Decafnation he has already begun contacting representatives from the development community, regional technical staff, stakeholders, elected officials, regulatory agencies, creek and stream stewardship groups and the K’omoks First Nations. The planning will get underway in early 2019.

The city has set aside $110,000 to develop the plan, and will get additional funding assistance from the Municipal Natural Asset Initiative (MNAI), a collective that supports municipalities to better understand, value and manage its natural assets onan equivalent basis with its other infrastructure.

“I look forward to facilitating that conversation with the bigger group,” he said.

Town of Comox

Comox does not have a town-wide stormwater management plan, but has created detailed plans for specific developments, such as the North East neighbourhood..

On paper, the North East neighbourhood stormwater management plan looks to be the most progressive for a subdivision in the Comox Valley.

However, the green infrastructure recommended in a plan commissioned by the area’s land owners and developers from McElhanney Consulting Services Ltd., has not been adopted by the town into bylaws that fund and manage their long-term operation.

So, it is unknown at this point whether these green infrastructure policies will actually be implemented, or enforced.

Town of Comox Municipal Engineer Shelley Ashfield refused to meet with Decafnation to discuss the town’s plans. Instead she answered some email questions and referred us to links on the town’s website.

Vegetated property cleared for condos near the Comox Golf Club. Town says no source control on rainwater will apply

If fully enacted, the McElhanney report recommends a variety of source control measures for eventual North East homeowners. These include rainwater harvesting, disconnecting downspouts from stormwater pipes, rock pits (infiltration pits), green roofs, amended soil for rain gardens and permeable pavement for driveways.

The report also recommends the town require narrow streets for less impervious surface, town-owned rain gardens in roundabouts and boulevards, and infiltration galleries.

McElhanney expressed concern in its report about the possibility that homeowners and the town would not maintain or protect the green infrastructure features, which could result in their failure and cause flooding and other problems.

“Given the potential difficulties in enforcing the ongoing maintenance and upkeep … it has been decided that the water balance benefit derived from the use of these features ought to be significantly discounted, to ensure the long-term performance of the overall stormwater management system,” the report says.

To hedge against that possibility, the report suggests, “It may be prudent to approach the shift to greater reliance on Low Impact Development tentatively, by designing a few subdivisions on the basis of redundant capacity, and then monitoring for compliance with clearly worded and well-publicized operation and maintenance regulations.”

It appears the neighbourhood will get traditional stormwater conveyance in addition to requirements for green infrastructure

The engineers are recommending the creation of series of dry detention ponds connected by infiltration trenches that all ultimately flow into the Queens Ditch, which is a low-sloped ditch leading to the Strait of Georgia at the Point Holmes boat ramp.

And they recommend copious informational signs reminding homeowners of their responsibilities for managing rainwater on their property and not to damage town-owned green infrastructure.

Ashfield said the town is currently updating its Subdivision and Development Services Bylaw and she hopes to have it finalized by next spring. But she would not say whether all or some of the North East Comox stormwater recommendations would be included in the town-wide bylaw.

Asked via email whether the town asked for green infrastructure features in the redevelopment of the Comox mall, or in the development of new multi-family projects at the Comox Golf Course or on Anderton Road, Ashfield said it did not.

“These sites are per the town’s current Official Community Plan and as such are currently modeled with the town’s 2013 storm study,” Ashfield wrote.

She also said bioswales or other infiltration features were considered for the recent Robb Road renovation, but were rejected because of the installation and maintenance cost premium and soil condition.

Ashfield said the town would be an active participant in the Courtenay Integrated Stormwater Management Plan process.

“Anything upstream of the town drains into Brooklyn Creek and so is very important that all jurisdictions within any watershed work together …” she said.

Village of Cumberland

The majority of Cumberland’s rainwater is collected and is either combined with the sanitary sewer system or, where it is separated, directed to one of three wetland areas around the village.

Manager of Operations Rob Crisfield said the village does have some storm drainage systems where rainwater is collected into a bioswale and soaks away into the ground.

One of several rain gardens in the boulevards entering the Village of Cumberland

“This method is used in the new ditches that were established on Cumberland and Bedan roads as part of a (renovation) project in 2016-2017,” he told Decafnation. “Of course, this doesn’t always work, depending on soil conditions.”

The village also requires ground recharge infiltration methods in appropriate subdivisions to allow water to soak back into the ground without runoff. And it is looking at a man-made pond in the Carlisle Lane development as a retention pond.

“We are also looking at including the potential of rain gardens in our downtown enhancement plan when it is updated in the near future,” he said.

Comox Valley Regional District

Marc Rutten, the general manager of the regional district’s engineering services branch, says the CVRD has no stormwater infrastructure to manage.

But the regional district is responsible for land use planning in the rural areas and uses the development permit too to reduce natural hazards (steep slopes) and protect the natural environment (streams). The CVRD has mapped the entire district to identify steep ravines and slopes, and streams, with the goal of ensuring no adverse effects from water flows.

The CVRD also dictates that water flows before and after a property is developed remain equal, so that streams neither flood nor run dry. But the CVRD shifts responsibility to the landower to employ green infrastructure — minimizing impervious surfaces, ponds, rock pits, pervious pavers, etc. — to achieve that goal.

How a street-side rain garden functions

However, stormwater runoff from Courtenay and Comox does affect the CVRD wastewater treatment plant on Brent Road.

Inflow volumes at the treatment plant increase by 3.5 times during the rainy winter months, an indication that stormwater is leaking into the sanitary sewer system.

Rutten said current municipal bylaws don’t allow stormwater to be tied into sewer lines, but there are legacy connections, which were common 70 years ago. Courtenay and Comox have separated sewer and stormwater lines over the last 40 years.

But because sewer and stormwater pipes are usually buried side-by-side, stormwater can leak into a gravity sewage system, such as the Courtenay-Comox sewer lines.

A gravity sewer systems runs under atmospheric pressure and the pipes are generally 25 percent to 75 percent full and flowing downhill. There is generally not enough pressure inside the system to force sewage out of the pipe, but groundwater enters because when groundwater levels rise, static pressure is created to force the water into the sewer pipe through worn out gaskets in pipe section joints.

Darry Montieth, the CVRD’s manager of liquid waste planning, said the Ministry of Highways has some subdivision approval authority in rural areas, and maintains all rural ditches.

But in the developments where the CVRD does have approval authority, Montieth says the district stresses 30 metre riparian setbacks and steep slope guidelines and can require a stormwater drainage plan through the development permit process.

The future

“Stormwater runoff is one of the largest water pollution issues facing the U.S. today,” says Larry Levine, a senior attorney with the National Resource Defense Council, an international environmental advocacy group.

And the challenge for Canadian municipalities is to wholeheartedly embrace green infrastructure as the only affordable and effective long-term solution to how rainwater is managed.

Next: how other communities on Vancouver Island and around the world are meeting this challenge.

 

 

 

 

 

 

READ MORE

North East Comox Stormwater Management Plan

Green Communities Canada

Canadian Fresh Water Alliance

 

 

A SHORT GLOSSARY OF STORMWATER TERMS

Bioswales — A stormwater conveyance system similar, but larger than a rain garden (see below).

Evaporation — As water is heated by the sun, surface molecules become sufficiently energized to break free of the attractive force binding them together, and then evaporate and rise as invisible vapour in the atmosphere.

Green infrastructure — Any natural or built system that provides ecological benefits and help to maintain pre-development hydrology. It encompasses natural features like streams, wetlands, forests and parks, as well as engineered systems that manage urban runoff.

Groundwater — Subterranean water is held in crack and pore spaces. Depending on the geology, the groundwater can flow to support streams. It can also be tapped by wells. Some groundwater is very old and may have been there for thousands of years.

Hydrologic cycle — The endless circulation of water. From the beginning of time when water first appeared, it has been constant in quantity and continuously in motions. The same water molecules have been transferred time and time again from the oceans and the land into the atmosphere by evaporation, dropped on the land as precipitation and transferred back to the sea by rivers and ground water.

Low-impact development (LID) — The systems and practices that use or mimic natural processes that result in the infiltration, evapotranspiration or use of stormwater in order to protect water quality and associated aquatic habitat.

Precipitation — Rain, snow or hail from clouds. Clouds move around the world, propelled by air currents. For instance, when they rise over a mountain range, they cool, becoming so saturated with water that water begins to fall as, snow or hail, depending on the temperature of the surrounding air.

Rain garden — A miniature wetland in a residential setting, lower than the adjacent grade to collect rainwater from roofs, driveways or streets, thus allowing infiltration into the ground.

Runoff — Excessive rain or snowmelt can produce overland flow to creeks and ditches. Runoff is visible flow of water in rivers, creeks and lakes as the water stored in the basin drains out.

Transpiration — Water vapour is also emitted from plant leaves by a process called transpiration. Ever day an actively growing plant transpires five to 10 times as much water as it can hold at once.

 

 

 

 

Share This