Chedoke Creek Remediation

Chedoke Creek updates provided to Hamilton City Council and Standing Committees.

Chedoke Communication Updates

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.

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.

On December 20, 2022, the MECP Director approved the City's requested deadline extension to December 31, 2023, with all other items in the Order remaining in effect, and unaltered. On March 3, 2023, the MECP Director issued a revised amendment which requires that the in-water targeted dredging work be completed by August 31, 2023, with the remaining activities in the approved Chedoke Creek Workplan completed by December 31, 2023.

Subsequently on March 14, 2023, after positive and collaborative discussions between the City and the MECP, the MECP Director issued a revised amendment, which supports the City's concerns regarding the previous deadline and still expedites the remediation of Chedoke Creek. As such, the City is now required to complete the in-water targeted dredging work on or before October 31, 2023. The City has completed the permitting and approvals process and will inform the various internal and external stakeholders of this amendment to the Order.

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 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.

Diagram description

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.

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?

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 DredgingWork 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

DredgingTargeted 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:

Post – Dredging

To report a concern please call 905-546-2489 and state the call is related to Chedoke Creek.

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.

Environmental Assessments

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 StudyThis 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 StudyThis 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.

Policy development

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

Retrofits for Road Rehabilitation Projects/Low Impact Development Best Management Practices Policy

The City of Hamilton has taken all necessary steps to ensure wildlife and species at risk located within Chedoke Creek and Cootes Paradise are protected throughout the remediation process. These steps have been in accordance with all six governing bodies including the MECP, Hamilton Conservation Authority, Ministry of Transportation, Transport Canada, Fisheries and Oceans Canada and Royal Botanical Gardens to proceed with remediation work. Some of the measures taken include:

Pre-dredge/during dredge:

Post-dredge:

The dredging will occur in two separate dredge zones – north and south. Work will start at the north end of Chedoke Creek, near the Desjardin pedestrian bridge and will move southwards toward Kay Drage Park. Residents will be able to see the dredge machine from the waterfront trail and Desjardin pedestrian bridge while work occurs in the north zone.

Residents can still expect to see some work occurring in wet weather conditions.

Permitting requires that the creek flow remain unimpeded, so each dredge zone will be broken down into smaller isolated sections covering only ½ the creek.

Turbidity curtains separate the work zone and allow the creek to continue flowing, while also allowing the City to safely isolate from any wildlife and keep the dredge material from disrupting the rest of the creek.

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 2023. The goal of the targeted dredge project is to improve the condition of the creek prior to the beginning of the discharge event.

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.

Once the sediment is removed from the creek using the hydraulic dredge, it will be transported via pipeline to the dredge material management area which is located within Kay Drage Park. In order to remove and dispose of the sediment efficiently, dewatering will occur at the dredge material management area. A lined 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.

Sediment remaining in the Geotubes are anticipated to be disposed of offsite at a non‐ hazardous waste disposal facility. The disposal timeline will depend on the dredging completion date and the dewatering rate of the sediments. The contractor will monitor the dewatered sediment prior to disposal to ensure the material is fully dewatered, dry and passes a slump test to be classified as solid non‐ hazardous waste.

Dredging will be completed hydraulically. This means we will be vacuuming up the sediments (or solids) from the bottom of the creek. The hydraulic dredge utilizes a cutterhead and pump to vacuum and transport the sediments to the dredge material management area via pipeline. The average combined dredge depth will be approximately 1.0 m which will remove approximately 11,300 m3 of sediment from the bottom of the creek.

No – the site will look as it did before work started. Kay Drage Park is expected to be restored to its original condition and re-open to the public at project completion.