Trees Please Hamilton

Green Solutions to Air Pollution

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A summary of our Invasive Plants workshop

On May 29th, we held our Invasive Plants workshop.  Our amazing speakers were Nadia Cavallin, Lindsay Barr and Corey Burt of the Royal Botanical Gardens.   They covered a number of topics including: definition of invasive plants, real life examples and tools that can be used.

Invasive species is generally defined as not native and harms the natural environment.  It is one of the biggest threats to biodiversity and costs Canada approximately $13 – 50 billion dollars annually.

Our speakers brought in a number of examples to look at.
Our first plant was the Norway Maple.  Nadia explains that it is moving into natural areas and with its dense roots and canopy, little can grow underneath this tree.  One easy way to identify Norways is when you pluck a leaf and look at the stem, there will be a milky sap.

Photo 1 Norway

Nadia is holding up an example of the Norway Maple 

White Mulberry trees are hybridizing with our native Red Mulberry trees.  Our Red Mulberries are considered a Species at Risk.  Trying to distinguish White Mulberries from Red ones are challenging as most ones we see or have been planted are White Mulberries.  Red Mulberries leaves have fine hairs making it feel soft.  These hairs only appear when the tree matures.  The only real way of telling is by sending a sample to a genetic lab in Guelph for verification.  As well, you can contact Royal Botanical Gardens staff and they might be able to assist.

Privet is a shrub that is commonly found in our local nurseries.  At the RBG, it’s a challenge to get rid of.  It is one the top three invasive shrubs as well as Buckthorn and Honeysuckle.  Speaking of Honeysuckle, it’s berries are high in carbs and not protein.  So birds are unable to sustain long flights without having to stop and feed.

Multiflora Rose is very thorny.  One identifying feature mentioned at the talk was “it will rip your skin apart”.  Another identifying feature is taking a look at the bottom of the stem, the hairy part looks almost like a separate section.  Our native roses are more solid and the stem looks more continuous.
Multiflora Rose leaf
Tools that can be used:


Photo: Extractigator (orange handle – top of the photo), hatchet (middle) and tree girdler (bottom)

Extractor can be used to lift the entire plant out.  We found one local shop with two locations one on Barton and the other on Rymal Road that sells it for approximately $200 +HST.  Click here for store website.
Disposal must be done carefully.  When in a wooded area, invasives can be uprooted and if left, the plant can re-root themselves.  Lindsay often will hang buckthorns upside in trees to prevent the roots from touching the ground.


Lindsey extracts an invasive from the parking lot

A hatchet can be used to girdle a tree.  Go around the tree and cut through the inner bark this way you can slow down nutrients moving up and down the tree.  Lindsey clarifies that we want to be careful not to cut the tree down as that will cause the tree to sprout.  While girdling the tree will cause some sprouting, cutting it down will intensify the trees’ reaction.

A tree girdler is another tool that can be used.

Steps to get rid of invasives.
It basically cooks the plants.
Step 1: Place black tarp (could use thick black plastic garbage bags) to smother and heat up the invasives.  Depending on the invasive, could leave up to one year.  And leave anchored in place.  Can use rocks or garden staples.
Step 2: once the tarp / material is removed, layer at least 6 layers of newspaper down and place mulch or soil on top.  Make sure newspaper is wet to hold it down.
Step 3: create holes in the newspaper and mulch and plant native plants.

Main messages:
1) When at a nursery, ask for native species and keep asking.
2) Corey and Nadia explain the term “sterile”.  When buying a non-native the”sterile” label refers to that particular cultivar.  Examples of cultivars are: Emerald Queen Norway Maple and Crimson King Norway Maple.  So that two sterile Crimson Kings are not able to reproduce.  It can become fertile if two different ‘sterile’ cultivars mix and match.  And if for example, a Crimson King Norway crosses with another Norway of a different cultivar, the deep red leaves characteristic will probably be lost in the hybrid of the two cultivars.
3) When trying to remove Invasive Species, patience is key. Most of the time, it requires going back year after year and working away.
4) The impacts of Climate Change means more flooding and some invasives especially their seeds can travel by water for example, Giant Hogweed.  Shorter winters might mean that invasives are able to survive in our area when previously they couldn’t.

Grow Me instead

1) Grow Me Outside brochure.  A handy list of what to grow and what not to.
2) Early Detection and Distribution Mapping System is now available online to track new emerging invasive areas.  When caught early, it’s easier to manage.  For more information, click here.
3) Doug Tallamy’s book Bringing Nature Home is a great resource for what to plant instead.

A BIG thanks to Nadia, Lindsay and Corey for their insights, information and stories.  We learned so much!  Thanks to everyone who came out to attend our workshop and thanks to you our readers!


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Stormwater in Hamilton – An Engineering Perspective

A Municipal Hydraulics course available at McMaster University strongly reinforces the importance of the “Restoring Resilient Spaces” workshops promoting citizen activism and vigilance with stormwater management solutions within the City of Hamilton.

As mentioned in an earlier blog, a major portion of Hamilton’s sewer infrastructure is very old, particularly in the downtown regions of the city, where over 600 kilometres of combined sewer systems (sanitary sewage and stormwater collected together in a single pipe) wind underneath our feet. During periods of heavy rainfall, inflow from the combined sewer system can overwhelm the wastewater treatment facilities, leading to sewer overflow into Hamilton Harbour or the surrouding watersheds. These overflows often contain the really nasty stuff as well. A overflow of just 3% of the combined sewage for a given time period can contain 35% of the suspended solid material within the volume. It’s important to remember that on top of the environmental concerns for local wildlife, these wastes are getting dumped into Lake Ontario, where we source our drinking water from!

To Hamilton’s credit, work has been done to minimize the number of combined sewer overflows. Storage tanks have been set up to contain the overflow for later treatment when the system is back underneath capacity. The locations and capacities of these tanks are below:


This has reduced the quantity and frequency of untreated outflow by roughly 90%. Outflows that would be used more than two dozen times a year are now only used 2-3 times a year – far from a perfect solution, but its a step in the right direction.

It is still a temporary solution. Hamilton’s downtown population will continue to grow, especially much of the core now zoned for high-rise development. With more residents,  there will be more sanitary sewer flow.  Additionally, as climate change produces more frequent and violent storms, more stormwater performance will be demanded of our aging water systems.


During LRT construction, some of the pipes along the downtown corridor will be replaced by like-for-like pipes, or in some cases, upgraded to larger capacity pipes. These replacements will still be a combined sewer network – it would likely be far too costly and disruptive to switch from a combined sewer network to separated parallel networks for sanitary sewage and stormwater. Much of the 600 km network would have to be updated simultaneously for this monumental task.


Over time, the additional combined sewage will impact the wastewater treatment plants, forcing more plant and storage upgrades as the quantity of combined sewer overflow would rise to pre-intervention levels.

In Hamilton’s newer areas, there is a separated sewer system, with two parallel pipes, one for sanitary sewage collection, and one for stormwater uses. The sewage is sent to the water treatment plants, while the stormwater bypasses the treatment plant and is sent directly back into the watershed. In theory, this is much better than a combined sewer system because it reduces the energy and infrastructure costs. Two narrow pipes running side by side may require less pipe material than a single pipe that must be wide enough to carry both, and the wastewater treatment plant doesn’t need to have as large of a capacity to handle the inflow since its coming only from sanitary sewers.


However, these seperated sewer systems come with their own sets of problems. For one, the stormwater is directed back into our waterways completely untreated, but it can be far from clean. As it runs along the path of least resistance to the storm sewers, it collects dirt, asphalt, litter, oil, and other debris. Drains have covers to ensure larger debris doesn’t go through, but the materials that do pass through the grates can negatively affect our aquatic environments.


A partial solution to this are stormwater ponds (as shown above), where small debris can settle at the bottom of a man-made pond before the water is sent into the waterways. These ponds do require maintenance, such as clearing away the sediment on a timely basis, to sustain their mitigating effects on water pollution.


Another problem comes with intentional and unintentional cross-connections. Either deliberately or from a DIY project gone wrong, untreated sewage can get sent into our waterways. Garbage, fecal contamination and odour issues coming from the Red Hill Creek stormwater outflows spured Environment Hamilton’s “PipeWatch” community activism in 2002, with an unexpected revival one decade later in 2012.


As well, creating independent stormwater infrastructure is typically not done as conservatively or with the accuracy of sanitary sewage systems or combined sewer systems. Underestimating the capacity of these systems would mean that raw sewage could get pushed up onto the streets. This is a problem that most modern cities haven’t faced very frequently since the early days of municipal wastewater treatment in the 1800’s.

In comparison, stormwater sewers are considered “lower-risk” since in the event of a heavy storm exceeding stormwater capacity or causing a backup in the system, the water flooding your street (and your basement!) wouldn’t pose a significant health risk. The flow rate used to estimate s pipe sizes is calculated from a simple equation:

Stormwater3C – the runoff coefficient, is based on the land use and the associated soil infiltration and ground permeability, all of which depend on complex factors like the environment and interactions with the built infrastructure. For example, a more built-up area with the ground covered by pavement would have a higher C value. This is because less of the rainwater would infiltrate through the road compared to a natural environment, and as a result, more reliance would be put on the sanitary sewer system for drainage. Ranges for the runoff coefficients based on land use are given below:


I – the rainfall intensity, is determined from past rain events, and selected based on the “duration” and “design frequency”. “Duration” refers to the length of the rainfall event, and this value is usually matched to the length of time it takes water to clear out of the stormwater sewer system once it hits the ground. “Design frequency” is how often, on average, a storm of greater intensity is expected to happen. The standard in Ontario is 5 years, which is to say that stormwater pipes are under-developed to handle exceptional storms that happen, on average, once every 5 years. This is scary, because when the pipes cannot handle any more water, you get flooding! In addition, with climate change, these rare “5-year storms” are getting increasingly common. Additional urban development means that permeable soils that allow for natural protection against flooding will be replaced by asphalt and concrete. This will effectively increase the value of “C” – the runoff coefficient, and put more demand on the under-built stormwater system that was designed before development took place.


A – the drainage area, is also variable. Infrastructure and disruption of the natural flow patterns can change the effective drainage area. For example, if an area is leveled out for condo development, this can completely change the direction and speed the water flows. Some areas will inevitably find themselves with a larger drainage area than previously predicted.

Hopefully this has given you a bit more of an appreciation for the complexity and importance of our sewer networks, along with an indication of the fragility of these systems and the problems Hamilton has faced and will face in the coming years. With our growing city and aging infrastructure, it is more important than ever to citizen scientists to revitalize rain gardens and make the most of our green space.


Course Notes from Civil Engineering 3M03 – Municipal Hydraulics at McMaster University – Prof. Yiping Guo




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A tree of their own

In Michelle’s family last autumn, every one of her kids planted a tree from our Tree Giveaway on the Beach!  Now all of her children are watering and taking care of their own tree with dedication.  What a great way to spend some time outdoors together connecting with nature and improving their neighbourhood.

Thanks for sharing these fun photos, Michelle!






Two Serviceberries

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Trees Please Kick-off events

Trees Please begins tonight in the North End with a tree walk at Land’s Inlet, and tomorrow in Sherman at Lucy Day Park!  Inventory will begin the first week of June – keep an eye on our website for further schedule details.

Our final workshop in the Restoring Resilient Green Spaces is next Tuesday, May 29: Identifying Invasive Plants and What You Can Do.  There are still a few spots available, but make sure to register with us.

We look forward to seeing you there!


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Show off your native trees!

Thanks Logan and Roxanne for sharing this great story about your tree plantings!


From Roxanne:

“Tree planting is very important to Logan, for his birthday a few years back he asked for a tree as his present. Family and friends all contributed a few dollars and he purchased his first trees, an empire apple and a pear tree from a green house. He was also given another pear tree from the Green Party campaign that happened last summer. Then last fall he found out about your tree give away and he planted his service berry bushes. This year for Christmas he asked for an evergreen tree. His new mission is to save money to purchase a t-shirt from because they plant 10 trees for each purchase, I must say I am happy about this because we are running out of room on our property for any more trees!”

We love seeing this blossoming spring tree!  Send your photos of your beautiful native trees, and remember to pick up a sign from our office to show your neighbours why native trees matter to you.

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Vimy Oak Heritage Tree

There is a newly planted tree in Waterdown that recently obtained a heritage designation.  While quite an unusual situation, this sapling achieved this status because of its lineage.  A few acorns were picked up by Canadian soldier Leslie Miller after the Battle of Vimy Ridge and planted in Canada.  For the centennial anniversary, grafted descendants of these oaks were sent across the country, with one being planted with honour at the Waterdown Legion.


Photo: Barry Gray, the Hamilton Spectator


Photo: Barry Gray, the Hamilton Spectator

Although not a native tree, as we usually promote with Trees Please, this is a beautiful example of continued conservation for the sake of heritage.  An important tree is not simply a large one – we all have different criteria for the trees that are meaningful to us.  Is there a tree in your neighbourhood that means a lot to the community?  Perhaps it is hundreds of years old, a unique species, a peculiar shape, or perhaps it’s the common meeting spot.  We are interested in hearing about the trees you believe should get some designated protection!  Email with your stories and/or photos.

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Mother’s Day gift idea

While at the Beasley Fair this weekend, someone had a fantastic Mother’s Day idea!  Visit us at our office this week to pick up one of our beautiful tree signs with a donation…

I planted a native tree

And then go plant a native tree with the family!  Time spent together and a beneficial addition to your yard, what could be better?


A blossoming Red Bud planted by Michal from last year’s tree giveaway