TAMRMS#: B06
12.1
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Feasibility Report Removal of Sediment
Notice given by: Councillor Killick
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PURPOSE OF REPORT
The purpose of this report is to identify the impacts of the proposed motion for which Councillor Killick gave notice on June 20, 2022.
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PROPOSED MOTION(S):
recommendation
That administration prepares a report of the feasibility of:
1. Doing a pilot project to do low impact removal of historical manmade sediment from the river at one high impact location
2. That the location be focused on environmental (vs aesthetic) improvements to the health, rehabilitation and re-naturalization of the river
3. that any possible alternative funding sources, grants be identified
4. That the regulatory approval process be quantified, and that the info be available for review by the EAC by Q4 2022.
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ALIGNMENT TO PRIORITIES IN COUNCIL’S STRATEGIC PLAN
N/A.
ALIGNMENT TO LEVELS OF SERVICE DELIVERY
C.2.3 Management of Environmental Risks and Compliance - Provision of subject matter expertise on regulations and best management practices to assist in managing environmental risk and maintaining regulatory compliance.
• C.2.3 a Environmental Protection and Stewardship
• C.2.3 d Environmental Approvals and Permits
C.2.3 h Regulatory and External Agency Relations
ALIGNMENT TO COUNCIL DIRECTION OR MANDATORY STATUTORY PROVISION
N/A
BACKGROUND AND DISCUSSION
Council and residents often express concern about the perceived poor environmental condition of the Sturgeon River, and typically mention the amount of sediment that has built up over time, particularly in the downtown area. This sediment was introduced through stormwater inputs to the river, which often carries oils, grease, nutrients, grit, pesticides, bacteria, and salts from roadways. Although not a detailed feasibility report administration has considered the following:
Impacts of Dredging
It is a common perception that dredging the riverbed will remedy many of the ecological issues we have, when there are many other approaches to improve the Sturgeon River that would be more effective over time. Dredging is extremely costly, logistically difficult, destructive ecologically, and requires a tremendous amount of work to obtain the necessary regulatory approvals. Dredging can increase water flow speeds, causing more bank erosion, and may exacerbate downstream flooding if done at a large scale. It is most likely that removing sediment would cause more sediment to move in from upstream and fill the space. The river would require ongoing dredging to have any significant impact on sediment volumes and would need to be done in other areas of the watershed where sediments are contributed. From an ecosystem perspective, there are no drastic improvements to water quality, flooding or aquatic health expected from dredging the Sturgeon River.
Alternatively, dredging can increase the width and depth of the channel, remove obstructions to navigation, and restore some small areas of lost fish habitat. However, this is the case namely on large rivers used for shipping, and in reservoirs, and is done for aesthetic, navigational, gravel mining, and operational purposes (frequent practice in the United States).
Regulatory Requirements
Although not a detailed report as requested through the proposed motion it is anticipated, no matter the size of the project, that a full environmental impact assessment would need to be completed by a consultant prior to regulatory permits being granted. There would be five permits/reviews required to do this work, including:
• Water Act - Provincial (est. timeline 3-6 months)
• Public Lands Act - Provincial (est. timeline 6-12 months)
• Navigable Waters Act - Federal (est. timeline 3-6 months)
• Fisheries Act - Federal (est. timeline 3-6 months or more)
• Historical Resources Act clearance (est. timeline 3 months)
No work can begin until these permits are in place. In addition, there are many ancillary pieces associated with these permits, including but not limited to:
• Indigenous engagement
• Public notification
• Fish relocation (which requires a Fisheries permit)
• The use of an isolating in-water dam
• Construction supervision by a Qualified Aquatic Environment Specialist (QAES)
• Migratory Bird Act considerations
Dredging Research
Dredging itself requires specialized equipment. Common methods include using large, toothed equipment and a suction on a barge-type platform to loosen the sediment and carry it away; diver-assisted suction dredging (like a large vacuum hose), and sometimes a backhoe in smaller areas. In the case of the Sturgeon and its low flows, we would require a dredge with a vortex to separate the water from the sediments, returning the water to the river and removing the sediment for disposal. Dredge equipment is available in Alberta in limited quantities and is used in oil and gas applications or reservoir management. Finding equipment small enough to have minimal impact on the Sturgeon may be a challenge.
A brief scan of the scientific literature was conducted, and some of the environmental risks pulled from journals include:
• Entrainment of aquatic organisms by suction dredges
• Resuspension of sediments and fine particulate matter in the water column, especially during repeat dredging events, which can have the following effects:
o reduction in sunlight penetration, resulting in less photosynthesis from aquatic plants and declines in dissolved oxygen levels
o more heat absorption by sediment particles, thereby raising the temperature of the water
o biological impacts such as disruptions in migration, spawning, movement patterns, disease susceptibility, growth and development impacts, reduced hatching success and direct mortality
• Reduction in the amount and species richness of benthic invertebrates
• Creation of unstable banks and shifting sediments
• Damage to riparian areas through equipment travel or placement
• Acidification of surface waters through an increase in certain types of bacteria
• Increased concentrations of bioavailable nitrogen and phosphorus
• Up to a 50% reduction in macroinvertebrate biodiversity, abundance and biomass has been noted in short-term (<1 year) dredging projects
• Mobilization of any heavy metals that may be contained in anthropogenic sediments (i.e., copper, zinc)
The conclusion is, in the majority papers, dredging has minimal positive impacts aside from navigation improvement, and may cause longer-term negative ecosystem impacts, putting further strain on the Sturgeon’s fisheries. As such, Administration does not recommend proceeding with the development of a feasibility report on the topics identified.
Current Initiatives Improving the Health of the River
The City has been proactive with the installation of oil and grit interceptors (OGIs) on major high priority outfalls and is now installing them on the medium priority sites. OGIs intercept the incoming stormwater as it passes through the pipe, and directs it to a large settling chamber, where solids and other particulates can settle out. Hydrocarbons collect on the top of the water and are skimmed off before the water is released back into the river. Moving forward, they are a requirement for developers to install one on each inflow to stormwater management facilities, which eases the financial burden on the City. Annually, these chambers are cleaned out by hydrovac units. OGIs are preferred to dredging the river as these units not only catch sediment before it reaches the river, but also collect hydrocarbons from stormwater runoff.
Figure 1. Sample drawing of an OGI.
Other current initiatives improving the health of the river include:
• Continued involvement with and support of the North Saskatchewan Watershed Alliance and the Sturgeon River Watershed Alliance, to address larger watershed-scale issues such as poor tributary health, nutrient inputs, wetland loss, and degraded riparian health.
• Shared municipal implementation of the Sturgeon River Watershed Management Plan and adoption of Riparian and Wetland Policies into the City’s regulatory framework.
• Conservation of natural areas on the landscape, particularly any remaining wetlands.
• Control of invasive species present in the river, and quarterly water quality sampling.
STAKEHOLDER COMMUNICATIONS OR ENGAGEMENT
Stakeholder engagement would be a requirement for the regulatory permitting to complete this work, and would include public notices, open houses, and government-required Indigenous engagement.
Indigenous communities have a strong connection to the Sturgeon River valley, and engagement with these groups would be crucial.
A multi-departmental project team including Environment, Capital Projects Office, Communications, Recreation and Parks and Community Relations would need to be assembled to coordinate the feasibility study and ensure efficient delivery of the project if it proceeds.
IMPLICATIONS OF RECOMMENDATION(S)
Financial:
Administration is not recommending proceeding with the feasibility report. If Council wants to proceed, an additional motion to approved funding for consulting expertise in the amount of $100,000 from Stabilization reserve would be required.
Legal / Risk:
None at this time.
Program or Service:
This project would require the reallocation of some capacity of the City’s Environmental Coordinator that is presently planned to complete other aspects of that role, which may include wildlife considerations, natural areas management, or involvement in larger-scale capital projects.
Organizational:
Since this work is not in the Environment Branch workplan, other corporate initiatives and projects would need to be reprioritized/delayed.
ALTERNATIVES AND IMPLICATIONS CONSIDERED
If Council does not wish to support the proposed motion, the following alternatives could be considered:
Alternative 1. Do nothing
Alternative 2. Direct Administration to hire a consultant to complete the feasibility study and confirm the funding source for an estimated $100,000 towards this study. That the results of the study be provided to Council for consideration of funding a pilot.
Alternative 3. Direct Administration to add to their workplan in 2023 to provide Council with a report on alternative options for improving the health of the Sturgeon River that are not currently being pursued or implemented (as outlined above) for consideration in the 2024 budget process.
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Report Date: August 15, 2022
Author: Melissa Logan
Department: Human Resources, Safety and Environment
Assistant Deputy Chief Administrative Officer: Diane McMordie
Deputy Chief Administrative Officer: Kerry Hilts
Chief Administrative Officer: William Fletcher