Five Island Lake
PCBS and Five Island Lake
Five Island Lake Community Liaison Committee
Newsletter #4, November 1997
Dear Fellow Residents ...
Three years ago, November, 1994, many of us attended an important
meeting in the Fire Hall about the PCB situation. Two things
came out of that meeting:
- a commitment from the provincial government to clean up the PCB contamination in the Five Island Lake area
- the formation of this Community Liaison Committee.
Our mandate is to work with the community and the government to develop a remediation plan that is environmentally sound, technically viable and acceptable to the community.
Strategy
After discussions with local residents at a community meeting
held on November 20, 1996, we recommended a Lake Clean-Up Strategy
(see box, page 3) to deal with the PCB contaminated sediments
in Five Island Lake. This strategy involves dredging a layer
of sediments out of North Bay at the north end of the lake.
We presented this Strategy to Wayne Adams, Minister of Environment, and Don Downe, Minister of Transportation and Public Works in December, 1996. What's happened since then? Various tests have been carried out and a boat launch and control weir constructed. Now, very shortly, a pilot dredge test will start.
This newsletter is intended to bring you up to date. If you need more information, and especially if you are new to the area and want to know what the CLC is trying to do, please call the CLC member who lives nearest you (phone numbers on page 4).
Pilot Dredge Test Begins
Because every dredging situation is different, the next step
in carrying out the Clean Up Strategy is to test the dredging
and dewatering processes to see what works and what doesn't.
The Department of Transportation and Public Works has selected Laidlaw Environmental to carry out these pilot tests which will begin very soon. The purpose of the tests is:
- to confirm that current dredging methods are effective in the Five Island Lake sediments (which are fine and full of organic material)
- to identify special environmental controls or monitoring requirements needed during the full-scale operation
- to identify what surveys may be needed before and after the full scale project
- to confirm which dewatering techniques will be the most effective (when the sediments are first removed from the lake they will resemble a thin soup).
Environmental controls will be in place during the testing and different technologies will be assessed in terms of their accuracy and efficiency, and their ability to minimize the resuspension of sediments.
Schedule
Laidlaw Environmental will take about ten days to move the equipment
on to the site and then the actual dredging will probably start
around November 17, lasting one or two weeks. The contractor
will be using a conventional suction dredge with a high capacity
pump, and will also test two types of dewatering equipment:
a plate press and a centrifuge.
The land based equipment will be set up on the railway right-of-way and in the small parking area by the new boat launch.
Once the sediments have been dredged and dewatered they will be put in a container and stored on the site of the former salvage yard.
Full Scale Dredging: When?
Only a small amount of sediment will be removed from the lake
during these tests. At this point the Committee doesn't know
when full scale dredging will take place. This will depend on
how smoothly the pilot test goes and when funding is committed.
The earliest that full scale dredging could proceed would be
spring of 1998.
Control Weir Built
As one of the environmental controls needed before any of the
contaminated sediments are disturbed by dredging, a control
weir has now been built across the narrow neck between North
Bay and the rest of Five Island Lake. Water continues to flow
through the opening in the weir but, if necessary, North Bay
can now be temporarily isolated from the rest of Five Island
Lake.
To build the weir the old bridge was removed. Two cribs were constructed and rockfill was extended from both sides and into the cribs. The Department is looking into the feasibility of facing the rockfill on the north side with crushed limestone to help counteract the acidity of the water.
A new bridge was then built over the narrow (3.5 metres) opening. This opening can be closed by dropping stop logs (planks of wood) into a frame on either side.
Even with the stop logs in position, the control weir would still only act as a temporary dam. Water would continue to flow into North Bay. The water level would rise, perhaps very quickly if a large rainstorm came along, and would soon start flowing over the top of the stop logs. The control weir will however provide an extra margin of safety while the sediment is being removed.
If the dredging disturbs large amounts of sediment, the first line of defence is the siltation curtains surrounding the dredge. If the curtains could not contain the resuspended sediments, the control weir could be closed. This would buy time, probably several days, during which the dredging contractor would be able to use coagulants to settle out the suspended sediments.
The weir is not absolutely water-tight. Sections of the former railway bed were constructed of rockfill which is porous. The rockfill used to construct the weir is also porous but a geotextile fabric has been incorporated into the structure to capture fine sediment particles.
Test Results So Far
When the Committee put forward its Strategy there were a number
of unknowns relating to the Five Island Lake sediments and the
use of different clean-up technologies. The Community Liaison
Committee recommended moving ahead as quickly as possible on
the surveys and tests needed to answer these questions.
The Honourable Don Downe and the Honourable Wayne Adams made an initial commitment to fund the first round of tests, including treatment tests carried out in a laboratory on small amounts of sediments. Because the results were positive, the Minister announced funding for the pilot dredging and dewatering program to try out equipment and processes on site.
So far the Department of Transportation and Public Works and their consultants, Jacques Whitford, have completed the following tasks.
Collected More Information on North Bay
In order to be able to hire a dredging contractor and monitor
their work effectively, the Department needed the following
information:
- a detailed bathymetric survey (a contour map of the lake bottom)
- a map showing the location of any metal debris in the lake
- an aquatic vegetation survey (some plants can pose problems for certain types of dredge units)
- water quality sampling to provide a baseline against which to monitor the performance of the dredging contractor.
Tested Different Treatments on Sediments
from North Bay
Not all types of treatment work on all types of sediments, so
it was important to carry out several tests to see what will
work. All the testing so far has been "bench scale":
tests carried out in a laboratory using small quantities of
sediment. They included:
- evaluating the performance of coagulants which make fine suspended particles clump together and then sink to the bottom
- testing dewatering equipment to help dry out the sediments after they have been removed from the lake
- collecting physical information on the sediments in order to know how to move them around or store them temporarily on site
- trying out the thermal desorption technology on North Bay sediments.
Results
All of these tests were successful. In particular, the thermal
desorption bench scale tests were so successful at separating
the PCBs from the sediments, that the consultants say further
testing using larger quantities of sediment is unnecessary.
Lake Clean-Up Strategy: Re-Cap
1.Dredge the contaminated sediments out of North Bay
There is no other reliable, long term method of keeping
the PCBs from spreading further up the food chain and through
the lake system
2.Make sure that the dredging doesn’t make things worse
Test to make sure it can be done safely and use all
necessary environmental controls.
3.Investigate the viability of separating the PCBs from the
dredged sediments using thermal desorption
Transporting all of the sediments (potentially enough to
fill 400 dump trucks) a long distance could be prohibitively
expensive and risky. Thermal desorption, a non-burn separation
process (now proven to work on Five Island Lake sediments) could
reduce volumes and costs significantly.
4. Treat the contents of the 49 containers
on the site of the former salvage yard at the same time.
The containers were only intended to be a temporary solution,
and they could be a problem if access was needed to the contaminated
site beneath them. Therefore, if practical, the contents should
be disposed of at the same time as dealing with the lake sediments.
5. Send the PCBs away to be destroyed
off-site
Destruction through incineration at licensed facilities is the
only permanent solution.
PCB Destruction: Some Changes
To ensure a permanent solution the Community Liaison Committee's
Lake Clean-Up Strategy calls for dredging, dewatering, thermal
desorption to separate the PCBs from the sediments, and then
destruction of the PCBs.
Since the last newsletter various changes have taken place: the incinerator at Swan Hills in Alberta, which is the only licensed facility in Canada accepting out-of-province PCBs, has closed down temporarily. The US border, which has long been closed to shipments of PCBs, opened up only to close again a short time later in response to a court challenge.
So right now, if the dredging and thermal desorption were to be completed tomorrow, there would be nowhere to send the PCBs. However, no-one expects the situation to stay this way for long.
There are plans to reopen the Swan Hills facility to accept first liquids and then, early in 1998, solid materials. There are also licensed facilities in other provinces which could soon start accepting PCBs from other areas.
The two provincial departments are also continuing to watch developments in bioremediation (using microbes to treat the PCBs), but so far have not seen evidence that it works at full scale on Arochlor 1260, the type of PCB found in Five Island Lake.
The Committee will be monitoring the developments in PCB destruction and will keep you informed.
New Boat Launch
The Strategy also recognizes that some people with deeded access
to Five Island Lake could no longer get to their property because
boating is prohibited in North Bay (to avoid stirring up the
contaminated sediments). The Department of Transportation and
Public Works (TPW) has therefore constructed a new boat launch
to provide alternate access. Only affected property owners have
keys to the gate; the boat launch is not intended for general
public use. If you have questions please contact Christopher
Moir at TPW, 424-4725.
Your Community Representatives on the Five Island Lake Community Liaison Committee
Richmond Campbell, Cambrians Cove 876-7847
Andre Faubert, Lake of the Woods 876-8390
Wenda Greer, Cambrians Cove 876-0813
John Hoyt, Three Brooks 876-2722
Ken Jakeman, Lake of the Woods 876-2510
John Jardine, Five Island Lake 876-2724
Danny LeBlanc, Sheldrake Lake 876-8179
Joyce Milley, Hubley Lake Road 876-5000
Wayne Nicholson, Five Island Lake 876-2294
Murray Power, Sheldrake Lake 876-8236
Shawn Redmond, Glen Margaret 823-3068