Questions and Answers - Drag Lake Dam South Replacement
Trent-Severn Waterway National Historic Site
Q. What work will be completed at Drag Lake Dam South?
A. Parks Canada will be undertaking a full replacement of Drag Lake Dam South. Work will include the construction of two sluices, hydro intake and abutment walls, new mechanical equipment and public safety improvements. Construction began in mid-August and will take approximately one year to complete.
Q. Why does Drag Lake Dam South need to be replaced?
A. The Drag Lake Dams are an integral part of the water management system of the Trent-Severn Waterway. As part of the historic program of investment into the infrastructure supporting the Trent-Severn Waterway, Parks Canada is undertaking a major rehabilitation and replacement of the dams at the outflow of Drag Lake. At this location, there is a north and south concrete dam with extended concrete wingwalls branching off from the two structures.
Originally, Drag Lake Dam South was intended to be a major rehabilitation project along with the Drag Lake Dam North project. During the work on the north dam, further assessments were completed on the south dam which uncovered a higher level of deterioration than originally expected. These factors indicated that the dam is at, or nearing, the end of its normal expected service life, and requires a major intervention. Thus, the construction plan for the Drag Lake Dam South was revised from a major rehabilitation to a full replacement.
Q. Why did Drag Lake Dam North need a rehabilitation and not a replacement like the south dam?
A. The assessment of the north dam’s structural condition identified that the core of the concrete structure was in good condition with only peripheral deterioration of the concrete. Therefore, the north dam could be rehabilitated and safety elements added to extend its service life significantly, without having to replace it. During the work on the north dam, further assessments were completed on the south dam which uncovered a higher level of deterioration than originally expected. Due to this, Parks Canada completed further inspections on the south dam which determined that the approach to the work required on the south dam should be adjusted to a full replacement.
Q: Why didn’t Parks Canada know the condition of the dam before the project was started?
A: It is very commonly the case that the full extent of deterioration of the structure isn’t fully known until the rehabilitation work begins. This is despite the geotechnical drilling, testing and inspection work that is done by the third-party consultant in advance of the design. This evaluation is only localized in the areas tested and should represent a synopsis of the structure but that is not always the case. In addition, there are often areas of the dam that are unsafe to fully inspect when flows or water levels are high. In this case, some areas were unable to be inspected until flows and water levels were lower during the first construction period.
Q. Parks Canada notified the public of the project in 2016 and Drag Lake Dam North was completed in 2017. Why has it taken so long for the south dam to progress to construction?
A. The structures that make up the Trent-Severn Waterway National Historic Site, including the dams, locks and bridges, are historic and complex assets. Originally, Drag Lake Dam South was intended to be a major rehabilitation project along with the Drag Lake Dam North project. During the work on the north dam, further assessments were completed on the south uncovering a higher level of deterioration than originally expected. In order to effectively incorporate this new information, a complete review of the south dam was undertaken which led to defining the need to increase capacity to meet the current design criteria. Following this, the structure was redesigned and subsequently tendered which caused the delay.
These projects are managed using established program delivery practices to ensure quality work and value for Canadians. With heritage structures and such major required work, as is the case with the Drag Lake Dams, it is not uncommon for these projects to change.
Q. How will this construction impact local residents?
A. Parks Canada have made every effort to plan a project that reduces impact on residents. Since project commencement in August, the contractor was instructed to work within the hours of 7:00 a.m. – 8:00 p.m., Monday to Friday, and Saturdays as necessary. Recent high water levels on the Trent-Severn Waterway led to a work stoppage to accommodate the movement of water through the system. Work is back underway. However, due to the stoppage, the contractor will commence work on Saturdays from 8:00 a.m. – 5:00 p.m. beginning on November 6th, 2021 until the end of February 2022 in order to maintain project timelines. Work on Sundays from 9:00 a.m. – 4:00 p.m. can also be expected during this timeframe on an as-needed basis. Residents can expect construction noise and traffic during this time as this is unavoidable in a project of this size. However, it is expected to be restricted to daytime hours and will respect local by-laws, unless otherwise notified.
Q. Where can I find more information?
A. To find up-to-date news about this or other infrastructure projects in your area, please visit www.pc.gc.ca/tswHaliburton. To enroll for email updates about the project to replace the dam, please contact us at firstname.lastname@example.org and include “Drag Lake Dam” in the subject heading.
Q. How will Parks Canada manage water while the new dam is being constructed at Drag Lake Dam South?
A. Parks Canada manages water levels on the Trent-Severn Waterway to achieve a variety of objectives including navigation, mitigation of flooding, and the protection of the environment. Dams such as Drag Lake Dam South are essential infrastructure for public safety, and are rehabilitated and reconstructed as needed to ensure Parks Canada’s ability to meet these objectives. Parks Canada’s water management strategy is maintained during construction at this site by utilizing the north dam for daily requirements with measures put in place should an unexpected flow increase occur. There is no greater risk to upstream or downstream properties as a result of construction than presented normally.
Q. Has there been an environmental assessment done for this project?
A. Parks Canada’s environmental team is engaged right from the start of each project; scrutinizing project plans and processes and looking for ways to avoid, reduce or offset a project’s potential to impact our environment. They are also involved throughout construction to ensure all requirements are satisfied. A Basic Impact Assessment was completed by Parks Canada Agency for this project pursuant to Canadian Environmental Assessment Act, 2012.
At the Drag Lake Dams, the staging area that was used for the north dam will also be used for the south dam. Any vegetation or tree removal required of the project shall be completed in accordance with the Migratory Bird Convention Act. A vegetation replantation plan will be developed as part of the project’s requirements.
Q. Will the construction project impact fish species?
A. Adverse impacts to fish and fish habitat were assessed as part of the project’s Basic Impact Assessment. While efforts have been made to significantly reduce the impact of construction on fish species, some impact on fish habitat during dewatering may occur. An Environmental Management Plan will be implemented to ensure proper mitigations are followed.
No in-water works will occur between March 15th and July 15th of any year. In-water works will be completed in accordance with the Ministry of National Resources and Forestry fish timing window and Fisheries Act. .
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