COLLIERY DAMS TECHNICAL COMMITTEE STATUS UPDATE
COLLIERY DAMS TECHNICAL COMMITTEE, January 10, 2013
Mandate of Technical Committee:
On October 21, 2013 the City of Nanaimo struck the Technical Committee with a mandate to focus on outcomes that only involve remediating the existing dams, using the following phased approach:
- Phase 1: Review the existing data and direct additional data collection as necessary.
- Phase 2: Develop option(s) for remediating the existing dams that will satisfy the requirements of the Dam Safety Section of the Ministry of Forests, Lands and Natural Resources.
- Develop plans for short-term physical alterations to the dams in 2014 to provide the necessary time to carry out the long-term strategy (if required).
Composition of Technical Committee:
The Committee is comprised of representatives of the City; Snuneymuxw First Nation; the Colliery Dams Park Preservation Society; and engineering firm Golder Associates. Committee facilitator Katherine Gordon was appointed on November 26. Both Golder Associates and Gordon were appointed by the Committee after review of a number of candidates.
Katherine Gordon will act as the contact person in relation to any questions about these updates or the work of the Committee.
Role of Technical Committee:
The Committee is tasked with making viable recommendations on rehabilitation options to be reviewed by the City, Snuneymuxw First Nation and the Dam Safety Section. Those recommendations are to be made by February 28 2014 to the Executive Committee, which is comprised of City senior staff and Snuneymuxw advisors directed by the Chief. The Executive Committee oversees the Technical Committee and if necessary provides guidance and advice to the Technical Committee.
In due course the Executive Committee will provide commentary and recommendations to the Policy Group (Mayor and Council/Snuneymuxw Chief and Council) for consideration and discussion. As owner of the dams, City Council must make the final decision on which rehabilitation option to pursue and any short-term mitigation options required before permanent remediation takes place.
The parties involved at the table agree that this is a fair, credible process to follow.
Meetings of Technical Committee:
The Technical Committee has met twice, on December 5 and 13, and three meetings are scheduled for January to discuss communications and risk assessment approaches and technical options being developed by Golder Associates for committee consideration. Representatives of the Dam Safety Section attend meetings in order to ensure they are fully informed and are able to contribute to the progress of technical discussions.
Objective of Technical Committee:
The Committee has agreed on the following overarching objective for its work:
Development of an environmentally minimally invasive, cost- and time-effective solution while satisfying required safety standards – i.e. a solution that addresses:
- The safety of downstream residents and workers;
- Dam Safety Section requirements;
- The respective objectives of the City, Snuneymuxw First Nation, the Colliery Dam Park Preservation Society and the community;
- Environmental concerns, including fisheries habitat and ecology;
- Cost-effectiveness; and
- Having a timely permanent solution in place in 2014 if possible, but no later than 2015, with shorter term mitigation in place if required in 2014.
Approach to development of rehabilitation options
The Committee is combining work on Phases 1 and 2 of its assigned tasks. Golder Associates is in the process of reviewing the existing data and collecting additional data as required. The Committee has provided Golder with copies of historical and other relevant documents and reports and City staff are working with Golder to provide whatever support is required in order to conduct any additional physical site investigation of the Lower and Middle Dams.
The physical site investigation involves a limited geophysical examination of the two dams that will take place during the week of January 13. This is a non-invasive way to survey a large area of the dams with hand-held equipment that can be used in areas that are difficult to access with conventional drilling equipment and minimize disturbance to the dams and watercourses.
The objectives include providing information related to the internal dam fill zoning of the two dams, gathering information about the water table, underlying foundations and reinforcement (such as rebar) within the concrete wall, collect information which may help to establish whether a low-level-outlet may exist, and gather any other geophysical information, including seismic velocities, that will help in developing suitable remediation options.
The work will be carried out on land, is non-invasive and is not expected to have adverse
environmental impacts as the radar and seismic signal sources are all very low energy. However, it may be necessary, during one day of seismic surveying, to limit public access in order to minimize vibration noise during the seismic recordings. If this is the case, notices will be posted at entrances to the Colliery Dams Park and on the City of Nanaimo website, as well in local newspapers.
A second phase of site investigation will likely take place in the first half of February and involve investigative drilling in the embankments and concrete core of the dams. The geophysics work may provide information that will influence the scope of the drilling.
At the same time, Golder has adopted an approach which includes the revised (2013) Canadian Dam Association Dam Safety Guidelines to satisfy Dam Safety Section requirements. This approach applies a risk assessment methodology to the development of satisfactory rehabilitation options. Dam Safety Section staff have indicated that they are willing to work with this new approach. It is an approach that both governments and industry are increasingly moving towards in developing cost-effective strategies to address risk issues.
Over the next few weeks, Golder will be undertaking a risk assessment of the dams and concurrently developing technical remediation options. The preliminary work will be presented to the Committee in late January.
This document came from Colliery Dams Park Preservation Society on Jan. 10, 2013. Emphasis has been added in the case of the new Risk Assessment guidelines from the Canadian Dam Association which may have a bearing on the new assessment of risk associated with the dams.
On first glance this all looks promising but I don’t trust them; is the result going to be negative and will we see our lovely dams go next summer? It is revealing that nowhere in the document is the sheer beauty of the park noted, or the great recreational value provided to South Nanaimo, unequalled by any other area that I can think of in Nanaimo. But then this is Harewood.
We have heard sirens so often that we will forever automatically assume a false alarm, and in the case of an earthquake, the only event I can see damaging the dams, we will have much worse problems to contend with even though we do live right on the river.
I must admit I paid almost no attention to the Lantzville water situation last year.and would appreciate the background references that I’m sure you have provided in the blog.
The fact that the 2013 Canadian dam safety risk standards have been revised is encouraging and we will see where this leads. It was odd that previous calculations led to the deaths of hundreds, despite there being only one death in all of history in Canada for a death from the collapse of a dam (I think I am correct in this figure, but would welcome correction if I am wrong.)
Your concern about sirens is to be tested again this coming Wednesday at 10:30 am when another three minutes test will beckon the area to awareness (or, as you suggest, to dismissal).
Hope there isn’t a real dam breach at 10:30 am on Wednesday…..
Latest update from the Colliery Dams Technical Committee:
The Colliery Dams Technical Committee is pleased to provide the following public progress update, also available on the City of Nanaimo website. All of the Committee members remain focused on supporting the work that needs to be done to develop a remediation plan for the dams that will meet their collective objectives.
The Technical Committee was struck on October 21 2013 by the City of Nanaimo, with a mandate to develop remediation options to present to the City of Nanaimo and Snuneymuxw First Nation for consideration before a final decision is made. Mayor John Ruttan says: “I’m very pleased to hear that the Technical Committee is making substantial progress on the work that has to be done, and working collaboratively together on developing options for remediation of the Colliery Dams. We have a good short-term emergency plan in place in the meantime, and I’m looking forward to seeing the options and making progress very soon on a permanent solution.”
Here’s the link to the Technical Committee Public Status Update.
Click to access 140205CollieryDamsTechnicalCommitteePublicStatusUpdate.pdf
Core drilling scheduled at Lower Colliery Dam week of Feb 11-14
(Nanaimo BC, February 7, 2014) – Users of Colliery Dam Park are advised that workers will be onsite at the Lower Colliery Dam to undertake core drilling during the week of Feb 11-14. This investigation work is being conducted in support of ongoing efforts to gather information required to develop long-term solutions for both dams.
Two drilling rigs will be on site – one will drill core samples from the Lower Dam’s concrete wall; the second will drill samples of the Lower Dam’s fill.
Both drill rigs will be operating on top of the Lower Dam and will block the paved trail.
For the safety of park users, the trail will be closed and flaggers will be on site to direct users away from the work zone. The City anticipates undertaking the work from 7:00 a.m. to 5:00 p.m. each day, weather permitting. The work should be complete by Friday, February 14.
City of Nanaimo