Visit our rain gardens

 

 

 

 

 

 

 

 

 

 

 

 

A historic community

The community of Annieville, like much of North Delta, used to be covered by dense forest that soaked up rainwater like a sponge. Water not needed by the forest moved slowly through the soil, being cleaned and cooled, before reaching Annieville’s many streams such as McAdam, Collings, Norum, Honeymushroom, Kendale and Knudson.

With such a good water supply, salmon thrived in these streams, and in the Fraser River where the streams empty. Annieville’s First Nations and new settlers alike enjoyed the abundance of salmon in the area. In 1870, Annieville became the home of the very first salmon cannery in BC. During its first season, the cannery shipped over 30,000 pounds of salmon!

Since the 1960s, Annieville has grown rapidly. Most of the forest has been replaced by buildings and pavement – impervious surfaces that can’t absorb rainfall as the forest once did. Instead, rainfall runs off these surfaces, down storm drains and straight into salmon habitat. Warm polluted water has replaced the cool filtered water that once entered Annieville’s streams. Not surprisingly, salmon populations have plummeted. The salmon cannery is long gone.

One small step for salmon

In 2010 – 140 years after the opening of the old cannery – Annieville Elementary School became home to Delta’s third school rain garden (following Cougar Canyon in 2006 and Chalmers in 2009). Streamkeepers and Grade 4-7 students planted 300 shrubs and ground covers (purchased with funds from Delta, the Pacific Salmon Foundation, and Coast Capital Savings). The primary grades then mulched the entire garden with woodchips, which maximize water absorption and also protect against soil compaction, erosion and weeds. Almost immediately after planting, the garden began to do an excellent job of filtering and absorbing rainwater runoff from the school parking lot.

Functional limitations

Budget was not sufficient to allow for installing a new emergency overflow drain at the far end of the garden (as far away as possible from the water intake area).  So instead, Delta crews installed a riser on a pre-existing drain located at the intake.  The riser allows water to pool to a depth of about 5 centimeters; if it gets any deeper, it overflows down the emergency drain.

As the plants matured, the garden was able to absorb not only light to moderate runoff, but also quite heavy flows.  Unfortunately, when Delta School District repaved the parking lot in 2014, the new pavement was sloped such that a large portion of runoff flowed away from the rain garden and into an old-fashioned storm drain!  Ingrained habits are not easy to change!

The rain garden continues to do an excellent job nonetheless.  As for the runoff that now needlessly goes down a storm drain, we’re hopeful that the School District will eventually cut openings in the parking lot curb, to divert that water into the adjacent wide grass boulevard.  Simple as can be, no repaving necessary, boulevard trees will appreciate the additional water!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

At the Delwood Drive entrance to Brooke Elementary School there’s a large sloping lawn, with 4 street trees and 2 mature evergreens on it. What a perfect space for soaking up rainwater runoff from a pavement! Not only is there lots of room, but also all those trees (especially the large evergreens) are very good at soaking up water.

But the lawn is uphill from the school parking lot. Water doesn’t flow uphill, it flows downhill! What to do?

That’s easy! Delwood Drive is higher than the lawn – so instead of receiving rainwater runoff from the school parking lot, this rain garden receives runoff from the street.

The main challenge was figuring out how to get the water across the sidewalk. An attractive trench drain and some skilled concrete work by Delta staff have done the trick.

Brooke Rain Garden receives about 210,000 litres of rainwater runoff per year from Delwood Drive. This water used to be wasted down a storm drain, through a pipe, into Sunbury Creek and out to the Fraser River and the ocean. Now, the water helps to grow a beautiful garden. The nice thick layer of woodchips that students spread on the garden holds moisture in the soil, so that plant roots still find water even during a long summer dry spell.

With such a large lawn acting as an additional “sponge” right next to the garden, there’s no need for an emergency overflow drain. Whenever there’s a heavy rainfall and the garden can’t soak up water fast enough, any excess water flows out onto the lawn and gets soaked up there.

 

 

 

 

 

 

 

 

 

Blake Creek, a tributary of Cougar Creek

Like nearby Chalmers Elementary School, Burnsview Secondary lies in the watershed of Blake Creek, a tributary of Cougar Creek.  Though Blake is culverted along much of its upper reaches, it opens out into a beautiful little ravine that has some excellent spawning habitat.  From there, it flows into Lower Cougar Creek.

Environmental Science student project

Students of Mr. Benoit’s Environmental Science class approached Cougar Creek Streamkeepers to help them create a rain garden on their campus, as their Grade 11 project.   Their proposed site was a muddy area adjacent to the school’s driveway and bike racks.  Shortcutting across the site had seriously compacted the soils (and thus reduced their porosity) over many years.

Playing in the dirt

While a Delta School District crew tackled the main excavation with  mechanized equipment, students picked up shovels to dig the small area around the flagpole.  Including the flagpole within the rain garden has made lawn-mowing a little easier (fewer obstacles to mow around).

Steps through the garden

After much discussion, students and Streamkeepers alike agreed that it would be best to respect the traditional student shortcut diagonally up the slope to the sidewalk.  Streamkeepers provided some ultra-heavy recycled plastic landscape ties, to serve as steps up through the garden.  With much hammering and pounding, in went the steps and the rebar posts that hold them in place.

Total success:  The steps are heavily used, and they help provide a sense of ownership as students are welcomed into the garden rather than being expected to simply look at it or go around it.

No more mud puddle, and it looks good too!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A drainage problem

In addition to being environmentally friendly, rain gardens are also an economical way of dealing with drainage problems.  Case in point:  the entrance to the parking lot at Chalmers Elementary School in North Delta.

Years of car and foot traffic had caused settling of pavement and compaction of bare ground,  with the result that large puddles of rainwater and snowmelt regularly formed right beside the parking lot storm drain.

Despite the puddles, the storm drain nonetheless still managed to take in plenty of dirty runoff from the parking lot and pipe it directly into Blake Creek, a tributary of Cougar Creek.

In short, it was a situation of inadvertent “stormwater retention” that managed to cause significant inconvenience yet still didn’t protect the receiving creek from stormwater runoff.

A rain garden solution

Delta’s Engineering Department excavated a sunken garden to receive and absorb parking lot runoff. They re-positioned the storm drain – with a raised lip and surrounded by the rain garden – so that now it sends only excess water (if any) down the pipe to Blake Creek.

The garden design features a raised path of stepping stones, following the shortcut  route established by generations of students as they walk to and from school.

The students themselves planted the mugo pines, heathers, sword ferns, sedges, potentillas, roses and hens-&-chicks which fill their rain garden. Neighbours too volunteered their services, helping out with the planting and occasionally with maintenance (weeding, light pruning and litter patrol).

Garden performance improves with age

Unlike engineered stormwater management structures, which deteriorate over time, rain garden performance improves as plants mature.  Denser plant canopies trap more rainwater before it even reaches the ground, and much of that water evaporates back into the atmosphere.  Expanding roots and their associated soil organisms constantly create new porosities in the soil, making it capable of soaking up more water.

Chalmers Rain Garden, our 2nd oldest school rain garden in North Delta (after Cougar Canyon 1), is quite a small one.  Nonetheless, its performance has steadily improved as the plants have grown and thrived with minimal care from Streamkeepers and students.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Rainwater infiltration for drought-resistant creeks and forests

At first glance, the heart of Chalmers Park seemed an unlikely location for a rain garden.  There was no pavement to send polluted rainwater runoff down a pipe and into the nearest stream (Blake Creek, tributary of Lower Cougar Creek). But on closer inspection, Streamkeepers and Burnsview Secondary students from Mr. Benoit’s Environmental Studies class found 2 storm drains in the grass, that were serving to pipe away naturally-occurring “nuisance” seepage.

Water is not a nuisance, it’s a resource!  Whenever possible and safe (not near a steep slope, for example), it should be infiltrated into the ground.  Every additional drop in the ground means better summer flow in our creeks, and better-hydrated trees and forests that are less likely to burn during our increasingly hotter, longer, drier summers.

With financial assistance from North Delta Rotary and Nature Trust of BC, plus engineering and earthwork donated by the City of Delta,  Burnsview students and Streamkeepers created a linear rain garden that has brought additional beauty and biodiversity to the park.  The uphill of the 2 storm drains was closed off, and the downhill one (at the lowest end of the garden) now serves as emergency overflow only.  Though it’s impossible to measure the amount of natural seepage now flowing into the rain garden, clearly a significant volume of winter rainwater is being “banked” in nature’s free reservoir, the ground.  Seepage from this groundwater “savings account” helps streams and forests survive dry spells.

 

 

 

 

 

 

 

 

 

 

 

 

 

North Delta’s first school rain garden project

In 2006, Cougar Creek Streamkeepers, in cooperation with the Corporation of Delta, the Delta School District, and Stream of Dreams, applied for and received a $12,300 grant from the Pacific Salmon Foundation to install a demonstration rain garden at Cougar Canyon Elementary School, 11664 Lyon Road, North Delta, just across the street from the creek. The purpose of the rain garden is to absorb rainwater runoff and snowmelt from the school parking lot, and perhaps eventually from the street as well.

In late summer of 2006, Delta Engineering decommissioned two storm drains in the parking lot, replaced the solid curb with wheel stops, and excavated a sunken garden along the full length of the lot. They then installed highly absorbent soils, decorative boulders and a thin layer of gravel (imitation streambed), and planted a dozen trees.

The remaining 600 rain garden shrubs and ground covers were planted by students themselves (Seaquam Secondary’s Volunteer Club, plus every one of Cougar Canyon’s nearly 500 K-7 students), under the supervision of the Streamkeepers. Lawrence, a well-known and popular canine streamkeeper, served as Project Manager!

Stream of Dreams

In conjunction with the rain garden planting, Joan Carne of Stream of Dreams presented her highly informative and entertaining program on watershed health and stormwater management, to every class at Cougar Canyon Elementary. Thanks to Joan’s efforts, students were well-informed, enthusiastic and also respectful of their new rain garden.  To this day, neighbours comment on the remarkable absence of litter from the garden, compared to other areas (playing field, playground, etc).

Off to a good start

Shortly after the garden was installed, heavy rains and winds arrived, followed by heavy snow. The rain garden performed perfectly, absorbing virtually all of the rainwater and snowmelt. Grit, salt and other pollutants from the parking lot were filtered out by the garden, whereas before they would have gone down the drain and been piped directly into Cougar Creek.

Since its creation in fall 2006 …

Cougar Canyon Elementary School Rain Garden has become a well-known and popular neighbourhood feature.   Grade 4-5 maintenance teams are enthusiastic about weeding, trimming, and just hangin’ out in the garden chatting and looking at bugs and worms. Passersby often stop to admire the garden and compliment the kids on their success.

 

 

 

 

 

 

 

 

 

From the rain garden “live & learn” files

Cougar Canyon Elementary School Rain Garden had always functioned so perfectly, that when it came time to create a second one just the other side of the parking lot driveway, we were confident that it would work fine. So confident, in fact, that no overflow drain was provided.

Delta Engineering created their usual (or so we thought) imitation streambed, contoured the banks for planting, and arranged for safety fencing to be installed. In September 2009, students planted the garden with a generous supply of shrubs and groundcovers, purchased by Delta. Three deciduous trees were slated for later planting, once the weather became cooler and wetter.

All appeared to be fine. Until the first heavy rains, that is.

Oops! What was this lake? Why wasn’t the garden absorbing water quickly, as the first one had?  Was it the absence of trees? (8 evergreens and 3 deciduous in the first garden, none yet in the second one) Did we need more evergreen sedges and shrubs? Was the fire hydrant leaking?

While we pondered the possibilities, we also learned from Delta that the structure of the Rain Garden Extension was actually quite different from that of the main rain garden, despite their similar appearance. The Extension featured a very large volume of drain rock, wrapped in geotextile (landscape fabric), down the centre of the garden. By contrast, the main rain garden had been entirely filled with highly absorbent compost/soil – with just a skim coat of gravel on top.

But aren’t rocks good for drainage?

The accepted wisdom is that lots of “drain rock” is good for drainage. So it was with great trepidation that Streamkeepers and students set about the exhausting task of manually removing the tons (or so it seemed) of drain rock and their geotextile wrapper. Then we backfilled with highly-absorbent landfill compost, topped with just a thin layer of gravel. To our relief, this fixed the problem!

We’ve learned that rocks aren’t so good for drainage after all – at least not infiltration drainage. If the water has somewhere to go, then a thick layer of rocks can keep our feet dry while the underlying water flows away. But if we need to absorb water on site, rocks are not the best answer.

Do crows know best?

Rocks displace water. Every smart crow knows this! Just read about Aesop’s fable “The Crow and the Pitcher” – a story confirmed by experiments with modern-day corvids.

In contrast to rocks, soil with lots of organic matter does not displace water, instead it soaks up water like a sponge. The more roots and soil organisms, the more water the soil can soak up, and slowly release down to the subsoil and groundwater.

Beware the overuse of rocks in rain gardens!

In addition to displacing water, overuse of rocks may perhaps also inhibit absorption in 2 additional ways:

(1) Their sheer weight may compact the underlying soil so tightly that millions of small porosities are squeezed shut, thus preventing water from trickling down easily.

(2) Rocks (and geotextile) are not nearly as good habitat as soil and compost, for the countless roots, invertebrates and micro-organisms that also contribute to creating porosities into which water can trickle.

A surface cover of gravel and/or boulders is great for aesthetics, and for protection against erosion in places where water may flow vigorously. It’s also good as a maintenance path, from which weeding and trimming can be done.

But underneath that thin layer of rock, soil rich in organic matter makes for the most effective rain gardens.

 

 

 

 

 

 

 

 

 

Never doubt the power of a few committed people …

One teacher, one student – that’s all it took to make Delview Secondary School Rain Garden a reality. From selecting an excellent site at the south edge of the school parking lot, to getting permission from Delta School District and a grant from The Nature Trust of BC, to corralling a few family members and friends to move a small mountain of compost into the garden and then plant trees and shrubs – all this was initiated at Delview by just one teacher and one student.

The garden itself is a great success, absorbing all the parking lot runoff that drains into it, and sending not a drop down a pre-existing storm drain that now serves as emergency overflow. And not only does the garden absorb runoff, it also absorbs the flow from a natural seepage on the garden slope. All this, with a poorly-draining clay layer just 20 to 50 centimeters (8 to 20 inches) underneath the soil ….

Delview Rain Garden clearly demonstrates the impressive ability of plants, organic mulches, soils and soil organisms (macro and micro) to help us manage rainwater in an economical and environmentally-beneficial way.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

North Delta’s second most productive salmon stream

Every autumn, Streamkeepers regularly patrol Cougar Creek in search of coho and chum salmon spawners (95 sightings in 2015, 271 in 2016, 130 in 2017, 192 in 2018, 209 in 2019). McAdam Creek, in whose watershed Devon Gardens Elementary School is located, had not been patrolled in decades, if ever.

“Are there still salmon in McAdam Creek?”, we wondered, as plans took shape for a rain garden that would receive about 580,000 litres of runoff annually from the school parking lot ….

“Yes!” we learned, thanks to a few casual visits to the creek by Streamkeeper David Smith and Hemmera environmental consultant Jim Roberts. Between them, they logged 9 chum spawner sightings in just 3 visits – which means there were no doubt a lot more. In autumn 2016, David sighted 24 spawners in just two visits to McAdam.

This discovery “spawned” more than salmon fry, it also spawned the interest of some school staff and students, in learning more about McAdam. Principal David Hope and several Grade 7 volunteers explored the ravine, examined remains of a long-abandoned mink farm, picked up litter, removed invasive English ivy … and passed the word around that Devon Gardens has its own salmon stream just around the corner and down River Road.

Hopefully this beautiful little creek will benefit from additional rain gardens throughout its watershed.

 

 

 

 

 

 

 

 

 

 

 

 

 

Burnsview Secondary students take on SFPR mitigation projects: Phase 1

Students of Danick Benoit’s Environmental Science class at Burnsview Secondary School in North Delta suggested the creation of a park on the Fraser River shoreline, just east of the Alex Fraser Bridge, as an environmental mitigation measure for the South Fraser Perimeter Road (Highway 17). The site they had in mind had in fact already been earmarked for just such a park, the St. Mungo Recognifition Site (honouring First Nations and fisheries history).

So instead, the students took on a 2-phase rain garden project, financed by SFPR and with technical assistance from Cougar Creek Streamkeepers.

Phase I was dubbed “Fraser Falls” Rain Garden by the students, because this garden uses rainwater runoff that plummets down from open pipes on the underside of the Alex Fraser Bridge Approach high above. From 1986 when the bridge was built, until 2012 when the rain garden was planted, the only vegetation benefitting from this water were blackberries, reed canary grass and a few tansies. Now, hundreds of native plants — including trees, shrubs, ferns, groundcovers and sedges — are growing vigourously underneath the south end of the bridge.

Fraser Falls Rain Garden filters contaminants from bridge deck runoff, and also provides much-needed riparian vegetation for adjacent Cougar Creek as it flows through this industrialized area and out to the Fraser River. The garden also serves to welcome walkers and cyclists to a superb trail system that connects the Fraser River to Boundary Bay, passing many environmental treasures along the way.

Read about Phase II of the Burnsview students’ mitigation efforts under Tidewaters Rain Garden.

 

 

 

 

 

 

 

 

 

 

 

Once a forest, now a roundabout

Like nearby Annieville and Delview schools, Gibson Elementary occupies a site that was once densely-forested.  Many of North Delta’s salmon streams had their headwaters in this and nearby areas — including McAdam, Collings, Norum, Honeymushroom, Kendale and Knudson creeks.

Nowadays, stormwater from Gibson’s roof and parking lot is piped into Honeymushroom Creek.  Honeymushroom flows mostly in a culvert – the sad fate of many salmon streams – except for a short but potentially productive stretch just before it empties into the Fraser River.

The roundabout in front of the school offered a good opportunity to trap some of this stormwater runoff in a new rain garden, which would reduce pollutant loads and add to the natural groundwater flow to the creek.

Where there’s a will, there’s a way

It took 2 years of negotiations and planning, but Delta Engineering at last overcame 2 hurdles:  first, negotiating a drainage right-of-way so that municipal crews could work on School Board property; and second, designing a spillway that would bring additional water into the rain garden from 90th Avenue.

Here’s how that design works:

Runoff from 90th Avenue crosses the sidewalk in a trench drain, then flows down a spillway, into a small storm drain, underneath the pedestrian walkway, and through another trench drain into the rain garden.  Whew!

Planting time

After Delta had added 5 new trees to the roundabout, it was the turn of older students to plant shrubs, grasses, rushes and groundcovers.   Primary grades then mulched the entire garden with woodchips, which maximize water absorption and also protect against soil compaction, erosion and weeds.

We use arborist woodchips (from tree pruning or removal), which contain a “potluck” of wood types, leaves and needles.  Gardens thrive with this mulch.

Stunning ensemble

We knew that the existing roundabout trees – already quite large —  would “anchor” the new rain garden nicely.  However, until just a month before earthwork began, we had no idea that the blank wall behind these trees was to receive an impressive “wild BC” mural.  Delta rain garden designer Sarah Howie chose plants that beautifully complement the mood of this mural.

As with all densely-planted rain gardens, this one has become increasingly efficient at soaking up water, thanks to the growth of plant canopies, roots and soil organisms.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Prominent location

Commuters slow to 30 kph as they drive past Heath Traditional Elementary School on 72nd Avenue at 113th Street.  With Cougar Creek directly behind the school – deep in its beautiful canyon – and a busy thoroughfare directly in front, Heath seemed like the perfect location to advertise rain gardens.  A bus shelter, right in the middle of the proposed site, offered even more exposure.

One small problem

The only problem was that much of the runoff from the west parking lot was already infiltrating into either the grass boulevard or the Hydro right-of-way.  How could we justify the expense of a rain garden, when the site was already functioning as one (albeit not a very attractive one)?

Delta Engineering figured out how: by diverting runoff from 72nd Avenue itself, as well as enlarging the pre-existing intake from the school driveway in order to more effectively trap runoff.

The result has been a garden perfectly-sized for the runoff it’s receiving – capable of absorbing all the water, yet wet enough in heavy rains to clearly demonstrate its purpose and function.

Planting days

Delta Mayor Lois Jackson came to thank the students for their contribution, as they set to work planting 350 shrubs, ferns and groundcovers on November 3, 2011.  By the end of the next day, all plants were in the ground, and the entire garden had been mulched with woodchips.

Even at just a few months old, Heath Rain Garden proved itself to be not only highly valuable to Cougar Creek (it absorbs an estimated half million litres of water annually), but also one of our most well-known rain gardens.

Almost all North Deltans, and seemingly half of Surreyites as well, drive by this site at one time or another, if not daily. Interpretive signage near the bus shelter help educates the public (or at least some bored transit riders) about the important role that rain gardens can play in restoring salmon habitat and reducing the pollution of our creeks, rivers and oceans.

 

 

 

 

 

 

 

 

 

 

 

 

Rain garden raises school profile

“I never noticed there was a school here before,” remarked a passing neighbourhood resident to Hellings Elementary School principal Taj Reel, shortly after students planted their rain garden at the entrance to the school driveway.

Indeed, the entrance from 86th Avenue was not very eyecatching, and the school itself is set so far back as to be barely visible. The rain garden has focussed more attention on Hellings Elementary, and in addition, it makes a small contribution to the health of Bear Creek in Surrey.

Water doesn’t respect municipal boundaries – it simply flows downhill, whether in creeks, or as groundwater (underground water) or in storm sewers. Although Bear Creek is largely associated with Surrey (especially the beautiful stretches in Bear Creek Park), the Bear Creek Watershed extends into Delta and includes Hellings School.

Similarly, Cougar Creek is largely associated with North Delta, but a great deal of the water in the creek actually comes from the Surrey portion of its watershed.

 

 

 

 

 

 

 

 

 

 

Where paved no-parking zones once dominated the school entrance, Jarvis Elementary now boasts two rain gardens (one on either side of the entrance driveway), planted with a wide variety of low shrubs, ferns, flowering plants and groundcovers. An existing mature ‘Akebono’ cherry tree – a cloud of pale pink in spring – is the focal point of one of the gardens. A second young ‘Akebono’ has now joined it, in the garden on the other side of the driveway.

Four curb cuts guide about 665,000 litres of parking lot runoff per year into the rain gardens. There’s some overflow during the heaviest rains, down 2 pre-existing storm drains that are now surrounded by landscaping – but much of the parking lot runoff soaks into the ground where it can seep gradually to Blake Creek.

And of course, the school entrance looks so much better!

 

 

 

 

 

 

 

 

 

 

 

Perfect location, enthusiastic students

It’s rare that a rain garden “retrofit” meets with such ideal circumstances as at North Delta Secondary. There, almost the entire 83rd Avenue parking lot tilts to one corner of the lot, which just happened to abut a large expanse of grass, which just happened to have a storm drain already located within it. Perfect recipe for a meandering rain garden, with curb cut water intake at the highest end and the pre-existing storm drain at the lowest end, for emergency overflow if needed.

Enthusiastic student members of the school’s environmental club, and their equally enthusiastic advisor Robert Buchanan, applied for and received a Nature Trust Rain Garden Grant, negotiated with Delta School District to do the excavation and rough earthwork, did additional earthwork themselves, and then planted and mulched the garden in record time.

During heavy and/or extended rainfall, the young garden took in more parking lot runoff than it could absorb; much excess water overflowed down the storm drain. As it has matured, it has performed better and better – a feature of rain gardens that is in marked contrast to “built” infrastructure, which tends to decline over time. And of course the garden provides beauty and habitat as well, which no stormwater pipe can do.