The City of Hamilton was served a Ministry of the Environment, Conservation and Parks (MECP) Order on December 4, 2020, as a result of the Main/King Combined Sewer Overflow discharge that occurred between January 2014 and July 2018. The City of Hamilton has been working closely with the MECP and the Royal Botanical Gardens (RBG) to develop a remediation workplan for both Chedoke Creek and Cootes Paradise in response to the Order. Details can be found at www.hamilton.ca/ChedokeCreek
The Chedoke Creek Workplan outlines the steps associated with targeted dredging in Chedoke Creek. This work will remove nutrient laden sediment from the creek bottom and is scheduled to be completed before the end of 2022.
The goal of the targeted dredge project is to improve the condition of the creek prior to the beginning of the discharge event. As indicated in the MECP approved Chedoke Creek Workplan, the City implemented short term offsetting remediation projects in areas around lower Chedoke Creek and Princess Point to further improve the condition of the water. The Cootes Paradise Workplan addresses the long term offsetting work required by the order. The goal of the Cootes Paradise Workplan is to improve the quality of water into both Chedoke Creek and the receiving bodies of water.
Short Term Offsetting
As part of the Chedoke Creek Workplan, offsetting remediation projects have been completed to complement the targeted dredging work. Two initiatives including the installation of floating treatment wetlands and the installation of a small scale aeration system were undertaken to improve water quality conditions in the creek.
Floating Treatment Wetlands
Floating vegetative mats, also known as floating treatment wetlands, are used to manage and remove excess nutrients from surface waters under a variety of conditions. These wetlands are artificial floating platforms that allow aquatic plants to grow in sites of varying water levels. Native wetland species are planted on the platforms allowing aquatic root growth below into the underlying water. The roots trap suspended sediment and discourage growth of algae by reducing phosphorus and nitrogen, thereby improving water quality. The City has installed one floating treatment wetland within Cootes Paradise, with support from the RBG, which can be seen from the Desjardins Trail. Expansion of the project to other areas within Cootes Paradise is currently under evaluation.
- As pollutants enter the waterway, algae feeds off the harmful nutrients. The algae then multiplies, causing disruption to the natural ecosystem.
- The floating wetlands allow plants to grow above the algae. The roots then trap suspended sediments and discourages the growth of algae by reducing phosphorus and nitrogen from the water.
- Reduction in phosphorus and nitrogen therefore improves water quality, stimulating greater natural plant growth and a healthier habitat for fish, birds, insects and other wildlife.
Together the plants and bacteria create a living, breathing filter system that helps reduce the amount of contaminants and harmful nutrients in the water.
Small Scale Aeration
The City of Hamilton has installed a small scale aeration system in Chedoke Creek to help increase oxygen levels at the bottom of the creek while decreasing the amount of excess nutrients that contribute to algae blooms and cloudy water. Due to a decrease in temperature, the pumps are turned off in the winter months. The system is required to be removed for the targeted dredging activities to take place, but will be re-installed at the end of the project. A larger aeration system will be considered during the Lower Chedoke Creek Environmental Assessment Study.
How does it work?
- A compressor pumps air to the bottom of the creek through diffusers.
- In this process, the oxygen-poor water rises to the surface where it picks up oxygen from the diffusers and the surface.
- The oxygen-rich water then returns back down to the bottom where beneficial aerobic bacteria use the oxygen to digest organic matter, eliminating harmful excessive nutrients.
Removal - Targeted Dredging
The dredge activity will remove approximately 11,000 cubic metres of sediment including 24 tonnes of total phosphorus (TP) and 31 tonnes of total Kjeldahl nitrogen (TKN) from Chedoke Creek over a 4-5 month period.
Pre – Targeted Dredging
Work to complete the dredge design included a topographic survey, species at risk investigations, hydrologic & hydraulic modelling and sedimentation investigations. The sediment quality samples were collected at numerous locations within Chedoke Creek, the Princess Point Embayment and Cootes Paradise in the spring of 2021. Additional deeper samples were collected in August 2021 to better inform the dredge design. Based on the results and the design process, the project expects to remove 24 tonnes of TP and 31 tonnes of TKN within the targeted dredging area
Targeted dredging will occur within an identified area of Chedoke Creek to remove contaminated sediment from the creek bottom. Over a 4 – 5 month process the following activities will be completed:
- Preparation Work areas within the creek will be isolated using a turbidity/silt curtain that will have a weighted line to maintain contact with the bottom of the creek. The top float line will help isolate the work area at the surface. Fish and wildlife will be removed from the work area prior to the dredging activities by a qualified aquatic biologist, reducing potential interaction with the dredging operation in accordance with governing protocols.
- Removal Sediment will be removed from the creek bottom using a hydraulic dredge which utilizes a cutterhead and pump to vacuum and transport the sediments to the dredge material management area which is located within Kay Drage Park. The average combined dredge depth will be approximately 1.0 m which will remove approximately 11,000 m3 of sediment from the bottom of the creek.
- Dewatering Dewatering is the intentional removal of water from solid material or soil. In order to remove and dispose of the sediment efficiently, dewatering will occur at the dredge material management area. A trench will be built within the material management area to facilitate the dewatering process. The sediment slurry (mix of solid material and water) will be pumped into a geotextile container. An environmentally safe polymer is added to help bind the solids together and separate the water. The separated water will then drain from the geotextile container while the sediment remains inside. The separated water will be pumped to a nearby sanitary sewer main (on dry days only) to be treated at the Woodward Wastewater Treatment Plant. Once the container is full of sediment and the contents have dried, it will be hauled to a landfill.
- Repeat The dredge area has been broken up into two zones, North and South. The total dredge area spans between 100m north of the Desjardins Trail pedestrian bridge and 100m south of the Kay Drage Park bridge. Each zone will be broken-down into small sections so that only half the creek, as required by permitting, is blocked by dredging operations. Starting in the North Dredge Zone, after each section is completed, the contractor will reset in the next section and continue to dredge until complete. For updates on the dredging activities please visit the ArcGis Story map.
Post – Dredging
- Dredging and material removal is scheduled to be completed by the end of December 2022.
- Restoration works will occur at the material management area, Kay Drage Park in spring 2023.
- Surface water quality testing will continue after the dredge work has been completed. Results will be compared to historic data to determine the impacts of the dredge activity.
- Various post dredging monitoring efforts will take place to support each agency’s permitting and approval requirements including any changes in water levels, sediment quality of the newly exposed creek bottom and the functionality of any added species at risk habitat.
The timeline provided is an estimate based on acquiring appropriate approvals for dredging activities in a regulated waterway. There are several agencies at the Provincial and Federal level that must provide their approval prior to the work commencing.
- June/July 2022 - Kay Drage Park and Park Access Trail (located behind Nicholas Mancini Centre - Hunt Street) closure. Dredging preparations begin with staging of equipment at Kay Drage Park.
- July 16, 2022 - In-water dredge work begins. Note: This is the earliest start date since in-water work is restricted based on the Ministry of Northern Development, Mines, Natural Resources and Forestry regulations and the fish species present. Due to the fish species identified in Chedoke Creek, in-water work is prohibited from March 15 to July 15 each year.
- December 2022 - Planned project completion. Recreation Trail will reopen.
- Spring 2023 - Restoration. Kay Drage Park will re-open once the disturbed work areas are restored.
- Park Closure - Kay Drage Park will be closed for public access for the duration of the dredge activities. Starting June 2022 the Park will be used as a staging area for dredge preparations and will be utilized throughout the project as the dredge material management area. Upon project completion, the park will require restoration work and therefore it is expected it will reopen to the public in Spring 2023.
- Access Trail Closure - Located behind the Nicholas Mancini Centre (44 Hunt Street), is a trail that accesses Kay Drage Park. This trail will be closed to the public for the duration of the dredge activities and will reopen once the park restoration work has been completed. There is no expectation that the Desjardins Recreation Trail will be impacted. Signs will be posted should impacts arise.
- Transportation Routes - Trucks will be used to remove the sediment from the dredge material management area. Review the truck route map. Dredging activities will occur 5 days a week (Monday to Friday) with approximately two trucks an hour removing sediment.
- Odour - no expected impact due to the dredging method (hydraulic) and the dewatering method (geotextile containers) keeping the dredged material contained. Provisional odour mitigation tools will be utilized should odours become a nuisance.
- Noise - no expected impact, but should a concern arise, please report a noise concern to the number below.
- HSR - no expected impact as buses will be given priority on the trucking route.
- Public Health Services Advice - Avoid contact with water. Water may contain high levels of bacteria that can make you sick.
To report a concern please call 905-546-CITY (2489) and state the call is related to Chedoke Creek.
Long Term Offsetting
In response to the MECP Order, the City is implementing long term solutions to improve the quality of the water. Offsetting projects were identified in the Cootes Paradise Workplan focusing on long term solutions that improve the quality of water inflow into Chedoke Creek and the receiving bodies of water. The long term offsetting projects are identified through Environmental Assessments and Policy development.
The City is bound by the Provincial Environmental Assessment (EA) Act in its decision making related to municipal infrastructure. The three (3) Municipal Class EA studies identified below will include a detailed environmental, social and economic assessment of opportunities to improve water quality entering Chedoke Creek. Any alternatives identified will be evaluated through additional fieldwork, analysis (modelling) and agency/stakeholder/Indigenous engagement.
The studies will be conducted concurrently in 2022/23 and the identified preferred projects will advance into design in 2024 with construction expected in 2025/26. It is important to note that the Order does not specify completion deadlines for the proposed initiatives identified in the Cootes Paradise Workplan.
Study 1: Lower Chedoke Master EA Study
This study will involve a comprehensive review of the Lower Chedoke Creek environment to evaluate various alternatives in terms of their benefits, impacts, and life cycle costs to improve the ecology of the area including the inputs to Cootes Paradise and the Western Harbour. During the Cootes Paradise Workplan and Chedoke Creek Water Quality Improvement Framework studies, several potential remediation / restoration solutions were identified through stakeholder engagement and from previously completed studies. They included recommendations from RBG’s long-term strategy outlined in its 25 Year Master Plan, such as large scale aeration and constructed wetlands. In addition to these solutions, the Lower Chedoke EA will consider stream naturalization, additional dredging, riparian vegetation, re-establishment of the Chedoke delta, as well as other infrastructure improvements.
Study 2: Chedoke Watershed Stormwater Retrofit Master EA Study
This study will involve an assessment of potential locations within the separated storm sewer areas of the Chedoke Creek Watershed for retrofit projects to improve the quality of stormwater runoff from the urban environment. The study will establish a long list of locations and approaches to water quality treatment such as pond retrofits, conveyance controls, low impact development measures, and other end-of-pipe alternatives. Ultimately, the intended outcome of this EA is to establish a strategy focused on addressing water quality treatment gaps over the long term.
Study 3: Ainslie Wood Municipal Class EA (Sewer Separation)
The study will involve completion of a Municipal Class Environmental Assessment to determine a preferred solution to separate the Chedoke Creek inputs into the combined sewer system in the Ainslie Wood neighbourhood and to identify an appropriate outlet for the separated flow. The creek input locations specifically include areas upstream of Blackwood Crescent and Carwyn Crescent, as well at the western extent of Iona Avenue.
The key study objectives are to reduce the frequency and volume of combined sewer overflows to Chedoke Creek and other downstream bodies of water, to free up capacity in the municipal sewer system, and to potentially increase the baseflow that will reach the creek.
Municipal policies provide guidance to staff and the public on how to best implement and manage activities within a municipality. As part of the Cootes Paradise Workplan, the following policies were identified as opportunities to mitigate impacts of future projects as they relate to stormwater management.
Future implementation of these policies will provide long-term benefits to infrastructure operations and capital upgrades. The policies below can be directly considered part of the offsetting works for Cootes Paradise and the West Harbour.
Stormwater Management Policy - Redevelopment Sites
- This policy will explore best management practices to reduce/treat stormwater impacts from redevelopment sites, including Low Impact Development (LID) opportunities.
Retrofits for Road Rehabilitation Projects/Low Impact Development Best Management Practices Policy
- This policy will focus on water quality treatment practices to be applied to road rehabilitation projects within the City, including Low Impact Development (LID) opportunities. Ongoing best management practice options will be identified to advance the City’s stormwater management guidance.
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