Five Island Lake
PCBS and Five Island Lake
Five Island Lake Community Liaison Committee
Newsletter #3, October 1996
Dear Fellow Residents
This is our third newsletter (if you haven't received issues #1 and 2 call your community
representative listed on page 12). In Newsletter #2 we talked about the pros and cons of
either (a) dredging contaminated sediments out of Five Island Lake or (b)leaving them
where they are and trying to reduce the environmental impacts.
In this newsletter we carry on the discussion: if we dredge the sediments, what would happen to them? What treatment and disposal options are available? What are the costs and what are the uncertainties?
Together, the three newsletters should give you the basic information you need to make sense of the lake clean-up situation.
We realize that this is a lot of reading, and commend those of you who have stayed the course! Now we really need your feedback. Please consider the questions on page 11 and then either call your community representative, or fax/mail back the feedback form preferably by November 5.
Please don't feel you have to have a lot of scientific or technical knowledge to make a useful contribution. Without input from the community the Liaison Committee cannot do its job.
Recap: To Dredge or Not To DredgeNewsletter #2 looked at three options to address the problem of PCB contamination in the sediments of North Bay in Five Island Lake:
Option 1 Managing the Sediments in Place
Leave the sediments in place but greatly restrict the flow of water in and out of North
Bay and to ban recreational use of this area of the lake.
Option 2 Covering the Sedimeats in Place
Leave the North Bay sediments in place and cover them with a synthetic fabric and then a
layer of clean sand so that they won't spread further through the lake system.
Option 3 Sediment Removal, Treatment and Disposal
Dredge the North Bay sediments, and then treat and/or dispose of them.
Options 1 and 2 do not remove the PCBs from the lake but do contain them to a certain extent. Options 1 and 2 both reduce the chance of people coming into contact with the PCBs. Option 2 also reduces the chance of aquatic animals being exposed to PCBs.
Option 1 would gradually cause North Bay to become stagnant and eventually fill in, becoming more swamp than lake. Option 2 would not have this effect and would better contain the sediments, but there are questions about its effectiveness in the long term.
Option 3 permanently removes a large amount of PCBs from the lake system, but dredging, by itself, does not solve the whole problem - something has to be done with the contaminated sediments, and that "something" is what this newsletter is about.
If dredging is picked as the solution, how much material would be removed, what would it be like and where would it go?
If the Lake Were Dredged........ ?
How Much
If a decision were made to dredge the lake, the next question would be how far and how
much.
North Bay, the upper part of Five Island Lake, has acted as a natural settling pond and
probably holds about 70 percent of the PCBs now in the lake system. PCB concentrations in
this area range from 10 to 200 ppm.
The PCBs that have escaped from North Bay are more thinly distributed and, as explained in
Newsletter #2, would be technically very difficult and costly to retrieve.
To clean up North Bay so that remaining PCB concentrations would be around 1 ppm - probably the best that could be achieved - would mean dredging 30-45 centimetres or about a foot of sediment over the entire area (5 hectares or 12 acres). This would mean removing a total of 15,000 cubic metres of sediments (a standard dump truck holds 10 cubic metres).
If dredging continued into the main body of Five Island Lake from North Bay the cost would rise dramatically, but the retrieval rate would drop.
The consistency of the sediments
The sediments in North Bay are made up of mostly very fine particles. A high percentage is
likely to be organic material (vegetation and animal matter that has decayed). The
sediments would therefore still hold a lot of water, which would have to be removed
whatever treatment or disposal option was used. Either a centrifuge (a spinning device) or
a filter press would probably be used to dewater the sediments.
While PCBs don't readily dissolve in water, they could be attached to fine sediments still in suspension after the dewatering. Therefore the water separated from the sediments may have to be treated before being released into North Bay again.
Even after dewatering, the sediments will probably still have a high water content. This wet material may be difficult to handle or transport. It is likely that some dry uncontaminated soil will have to be added to it to help stabilize the dewatered sediments before further handling or transportation.
This is one of the uncertainties involved: until the technical people know the exact composition of the dewatered sediments, they won't know the total quantity of material to be handled, transported or treated.
Staging area
These activities - dewatering and adding soil - would likely happen in an area next to
North Bay and would take several months. About an acre of land would be needed. This
staging area could be located further away but the whole process would be less efficient.
Since the release of PCBs into the environment was first identified as a serious worldwide problem in the 1970s, many technologies have claimed to cleanup or contain PCB contaminated soils and sediments.
Some perform well and some not so well. Some only work in certain circumstances; for soils but not sediments for example. Sorting out the claims of all these technologies is often the most difficult task facing a community with a contaminated site.
Luckily it isn't necessary to start from scratch each time. In the last few years PCB remediation technologies have been reviewed for the following projects:
- the Sydney Tar Ponds
- a government proposal to bring in a mobile incineration unit to deal with the PCBs in storage in Atlantic Canada
- clean-ups at military bases in Goose Bay, Labrador and Argentia, Newfoundland.
Types of Remedial Technologies
To assist the Community Liaison Committee, Jacques Whitford Environmental Limited
pre-screened a long list of 24 PCB remedial technologies. This list included all the
technologies that are now commercially available, as well as emerging technologies. They
fall into three main categories:
Containment
The PCBs aren't changed or destroyed but permanently sealed off from any exposure to the
environment.
Minimization
The PCBs are extracted from the soil or sediments, thereby minimizing the volume of waste
to be treated and reducing costs. Minimization technology is often subsequently combined
with a destruction technology.
Destruction
The PCBs are permanently destroyed through the use of thermal, chemical or biological
processes. (Only thermal processes have been demonstrated on a commercial basis in
Canada).
Questions
These were the questions asked about each technology:
- Will it comply with Canadian regulations?
- How effective is it in reducing risk of exposure to PCBs?
- Is it commercially available and/or demonstrated on a full scale project?
- Has it been shown to work with lake sediments (as opposed to soils)?
- Will it handle large quantities of materials?
- Could the technology create other potential environmental problems (by releasing other
chemicals for example)?
- Does use of the technology create long term liability problems?
- Will this technology work in the Five Island Lake situation?
At this stage no technology has been rejected on the grounds of cost, although the Committee recognizes that this will need to be taken into consideration.
The Short ListOut of the long list, four basic options were recommended by the consultants for further assessment:
Why These Options and Not Others?A. Bury the contaminated sediments in a secure containment berm to be constructed near the site of the former salvage yard (containment).
B. Transport the sediments directly to an incinerator of-site, which could be the Bovar incinerator at Swan Hills in Alberta, or a facility in the US if the federal government changes current regulations banning the movement of PCBs across the border (destruction).
C. Transport the sediments to a thermal desorption facility, extract the PCBs, ship them to an incinerator in Alberta or the US, bury the remaining solids (minimization combined with destruction).
D. Bring in a mobile thermal desorption unit to Five Island Lake, extract the PCBs, ship them to an incinerator in Alberta or the US, and bury the remaining solids (minimization combined with destruction).
This is always a difficult question, especially as claims about new technologies are being made constantly. As explained to the Committee by the consultants, Jacques Whitford, these were the key reasons for rejecting other options at this time :
Out-of Province Landfilling
Local municipal landfills will not accept PCB contaminated sediments. Nova Scotia does not
have a hazardous waste landfill. A facility in another province or possibly the US could
be used,
but this would leave the Nova Scotia government with an unacceptable long term out-of province liability. If, sometime in the future, the owners of the landfill went out of business or mismanaged the landfill the Province could still be liable for clean-up costs, without having any direct control.
Solidification/Stabilization
These technologies involve solidifying the contaminated sediments before disposing of
them. They have not been successfully demonstrated for PCB contaminated sediments on a
commercial basis.
Soil Washing
This technology has not been proven to handle PCBs well since PCBs do not readily dissolve
in water. In addition it is not effective for fine grained, organic rich material, such as
the North Bay sediments.
Solvent Extraction
PCBs do dissolve in certain solvents but in this technology the solvents themselves can
remain in the sediments causing new and perhaps more serious problems.
The Eco Logic Process
Many people have heard of the Eco Logic process which uses a high temperature chemical
reaction process (not burning) to destroy the PCBs. The technology is already being used
for some applications, but has not yet demonstrated that it can handle large quantities of
sediments on a continuous basis. It is not clear when this component of the technology
will be demonstrated. If it took place before a final decision had to be made, this option
could still be considered, but the consultants could not recommend the use of Eco Logic at
this time.
Chemical Processes
There are a number of chemical destruction processes potentially available to clean up PCB
contaminated soils. Some of these processes produce hazardous by-products and many have
not been successfully demonstrated on a commercial basis.
Mobile Incineration Technology
Mobile or transportable incinerators have been successfully used at a number of
contaminated sites in Canada and the US. But getting public acceptance has often been
difficult. In 1994 a mobile incinerator in Nova Scotia was rejected during the
environmental assessment process, not on environmental reasons but because of community
opposition.
Bioremediation
Great advances are being made in the use of microorganisms to solve a range of waste
problems, and some day there may be a proven bioremediation process that can destroy PCBs
on a commercial scale. At present success has been limited, and usually only for very
small quantities of material contaminated with the types of PCBs that are more easily
degraded. At Five Island Lake the most commonly found type of PCB is Arochlor 1260 which
is much more difficult for microorganisms to break down and therefore less suited for
bioremediation.
The Committee knows that costs have to be an important part of the clean-up decision, along with environmental protection and community considerations.
Jacques Whitford have provided the Committee with some very preliminary cost estimates which we have included with the description of each option.
At this stage the Committee wants to establich strongly that all these cost estimates could change, and, for some options, could change dramatically.
Here are the main uncertainties:
The consistency of the sediments after they have been dredged and dewatered:
This could affect the cost of stabilizing, handling and transporting the material
The ability of the thermal desorption technology to handle the organics-rich North Bay sediments:
This could drastically affect how long it takes to treat the sediments, and the cost of disposing of the extracted PCBs and of the residual solid material.
Environmental assessment requirements: It is not clear whether any or all of the options would need to go through federal or provincial environmental assessment, which would add to the time and costs.
A second key point is that some options have ongoing annual costs for maintenance and monitoring which become significant over the long term.
Options Recommended for Further Study
1. Managing the Sediments in Place
(Described in more detail in Newsletter #2)
A permanent control weir would be built at the railway trestle to isolate North Bay
from the rest of Five Island Lake. Western Brook would also be redirected. Swimming and
boating in North Bay would be permanently restricted.
Estimated construction cost: about $160,000
Ongoing costs for monitoring and maintenance: about $30,000/year
2. Covering the Sediments in Place(Described in more detail in Newsletter #2)
A temporary control weir would be constructed at the railway trestle and
Western Brook would be diverted for a short time. The contaminated sediments in North Bay
would then be covered with a layer of geotextile fabric, topped by a 0.5 metre layer of
clean sand. When the covering was complete, the control weir would be removed and Western
Brook restored.
Estimated construction cost: about $2.5 million
Ongoing costs for monitoring and maintenance: about $50,000/year
A new site would have to be found for a containment berm (an above ground earth
structure lined and capped to prevent water passing through it). There is now no room on
the site of the former salvage yard. Approximately 2,500-4,000 square metres of land
(between half and one acre) would be required. Monitoring wells would be constructed
around the perimeter of the berm and long term monitoring carried out.
Estimated construction cost: about $6 million
Ongoing costs for monitoring and maintenance: about $65,000/year
Positive Features
- PCBs are inert and relatively immobile and are therefore easy to contain permanently in
a lined and capped berm.
- This is known technology with few risks.
- If circumstances change, the contaminated material could be treated at a later date.
Limitation
- The PCBs will be contained but will still remain in the community
- It may be difficult to get the needed permits and approval for this option.
After being dewatered and stabilized with added soil, the sediments would be transported by road or rail directly to an incinerator. At present Bovar at Swan Hills is the only permanent incinerator licensed to take PCBs in Canada. PCBs cannot be transported over the US border, but there are indications that this restriction may soon be lifted and this could allow use of incineration options in the US.
Estimated cost: at least 13 million (could be more depending on the consistency of the sediments).
Positive Features
- The PCBs are removed from the community and destroyed.
- High temperature incineration is a proven technology to destroy PCBs.
- There would be no concern about long term liability.
Limitations
- Because of the large volumes and long transportation distances, this is a very high cost
option.
- There is considerable uncertainty about the volumes of sediments to be transported and incinerated because of the soil that would be added to stabilize the material for transportation.
- The greater the volume of contaminated material to be transported, the greater the risk that an accident or spill could occur.
3-C. Transport the Sediments to a Thermal Desorption Facility; Incinerate the Extracted PCBsThermal desorption is a process which uses heat in an oxygen-free chamber to turn the organic chemicals in soils or sediments into gases. These gases then condense in a separate chamber and can be removed. The sediments or soils do not burn because they are never exposed to a flame. Thermal desorption units are routinely used in the US, but have had only limited application in Canada. After dewatering and stabilization the sediments would be transported by road or rail to a facility somewhere in Canada or possibly the US. The PCBs would be recovered in the form of an oil. This would be sent either to Alberta or perhaps a US facility for incineration. Until tests are carried out on the sediments in North Bay, nobody knows what quantities of either PCBs or residual solids would be produced by the thermal desorption process.
Estimated cost: at least 8.5 million (until tests are carried out this cost estimate is very tentative, the final cost could be much higher if difficulties are encountered).
Positive Features
- The PCBs are removed from the community and destroyed.
- By extracting the PCBs and thereby reducing the volume of material that needs to be incinerated, the transportation costs to an incinerator would be greatly reduced.
Limitations
- Because large volumes of sediments must be transported out of province, the costs would still be very high.
- Although thermal desorption is used in the US it has received only limited approval in Canada. Tests are currently being carried out in Quebec to see if the technology can meet Canada's air quality emission regulations that are stricter than the US regulations.
- Although thermal desorption facilities in the US have handled sediments as well as soils, tests would be required for the Five Island Lake sediments which contain a high percentage of organic material. These tests are needed in order to estimate what the final disposal costs would be.
- There are no permanent out-of province thermal desorption facilities. There is a temporary unit operating in Quebec, but we don't know if it would accept the contaminated sediments from Five Island Lake.
3-D. Use an On Site Mobile Thermal Desorption Unit to Extract the PCBs, Send them out of Nova Scotia for Incineration
This option would involve the operation of a mobile thermal desorption unit in the Five
Island Lake area. The sediments would be dewatered and stabilized and then put through the desorption unit to extract the PCBs which would be sent to Alberta or the US for destruction. The remaining treated solids would be buried on site. Until tests are carried out on the sediments in North Bay, nobody knows what quantities of either PCBs or residual solids would be produced by the thermal desorption. Once the job was finished, the unit would be removed.
Estimated cost: at least 8 million* (until tests are carried out this cost estimate is very tentative, the final cost could be much higher if difficulties are encountered).
Positive Features
- The PCBs are removed from the community and destroyed.
- Like Option 3c, this option is cheaper than transporting the contaminated sediments all the way to Alberta for destruction.
- Thermal desorption is a proven technology in the US and Canada.
Limitations
- It will be necessary to install and operate the thermal desorption unit in the
community, probably for several months. This may be unacceptable to some residents.
- Depending on the results of current testing in Quebec, more data on air emissions could be to obtain federal and provincial approvals, and delays could be possible.
- Although thermal desorption facilities in the US have handled sediments as well as soils, tests would be required for the Five Island Lake sediments which contain a high percentage of organic material.
- The residual solids left after the PCBs have been removed will have to be buried on site.
- The NS Department of Environment has stated that it may be very difficult to get a permit for this type of equipment to operate in Nova Scotia.
* A Note About the Cost of Thermal Desorption
The Committee had expected that on-site thermal desorption would be considerably cheaper
than. off site thermal desorption because of reduced transportation costs. In fact the two
cost estimates are quite close. Apparently this is due to (a) the cost of bringing the
mobile equipment in, and (b) the sloppy consistency of the North Bay sediments - a lot of
water would probably be shipped to Alberta or the US as well as the actual PCBs.
So far we have spoken about the problem of the contaminated lake sediments in isolation, because the Committee believes that cleaning up this problem should be the first priority.
What about the other contaminated material on the site of the former salvage yard? If the sediments are dredged out of the lake and have to be treated and/or disposed of, can and should the other materials on the site be handled in the same way and at the same time?
The 49 containers on-site
The containers now storing PCB contaminated soils are intended to be a temporary solution.
The containers themselves will last for another 10-15 years. Furthermore, they are sitting
on top of the clay cap covering the unexcavated portion of the site. Until the containers
have been moved there is no way to do anything with this area should the need arise.
The containers hold an estimated 1,500 cubic metres of contaminated soil, with PCB concentrations over 50 ppm. Technically, any of the four options could also be used to treat or dispose of this material at the same time. Since these containers are a federally registered PCB storage site there are regulatory issues to be sorted out before the soils they contain could be incorporated in Options 3a to 3d. However, costs would rise, anywhere from $ 1 million to $4 million depending on the option.
The soil in the existing berms
This material is less contaminated (the levels are between 5 and 50 ppm). It does not fall
under existing PCB regulations, and is now safely contained in two specially constructed
berms. It could be excavated and added to the sediments, but there appears to be no
particular need to do this.
The contaminated soil and other materials under the clay cap
The Committee does not yet know what action is most appropriate for this area of the site.
In places under the clay cap, the contamination levels are known to be extremely high.
Excavating this area is likely to be difficult and would pose new risks. Groundwater
monitoring has indicated that the PCBs are not migrating out of this general area. It is
therefore unlikely that any of this material would be handled at the same time as the
contaminated lake sediments.
We, the members of the Community Liaison Committee, are trying to recommend a remediation plan that will be environmentally sound, technically viable and acceptable to the community.
We want to be able to make our recommendation for the first part of this plan - the
clean up of North Bay - later this fall. Newsletter #2 and Newsletter #3 together lay out
the key issues. Now we need to hear your opinions!
The reality is that a total clean-up will be impossible. Whatever happens, there will
still be some PCBs in the lake system, and there will still be PCBs on the site of the
former salvage yard that will require ongoing monitoring. Hawever, the Committee believes
that the situation can be significantly improved, hopefully to the point where
environmental impacts will be much less and the community of Five Island Lake will no
longer carry a stigma.
Please consider these questions.
l. Should the contaminated North Bay sediments be left where they are or removed from the lake?
2. If they are left where they are, should they be simply contained within North Bay by cutting this area off from the rest of the lake, or should they be physically covered up?
3. If you think the North Bay sediments should be dredged, what options for treatment and disposal would be acceptable to you?
4. How important is it to you to start the clean-up as soon as possible? If choosing a high cost option could delay the clean-up (or jeopardize it even starting) are any of the lower cost alternatives acceptable to you?
5. If you don't feel ready to make these decisions now, what information do you need?
6. Are you satisfied with the work of the Community Liaison Committee so far?
Feedback
Comments
- The sediment in North Bay should be left to nature's course; likely producing
minimal or acceptable concentrations of PCBs over the larger area. Actual damage to
wildlife has not been proven. We still have active families of loons, ducks, minnows and
spiders. Fish have been scarce since extensive building began.
- A recent article in the Mail Star by a UNB scientist suggests that there is a great deal of over-reaction to any dangers from PCBs.
- Eutrophication of the North Bay by sealing it off seems like the worst possible solution.
- I think the third option (sediment removal) is the best because it is a more permanent solution ..... This provides good long term and short term effectiveness, the first two aren 't guaranteed. The only way to prevent the PCBs from continuing to travel to other places is to get rid of them.
- I hope the provincial and federal government will keep a closer eye in the future so that salvage yards, dump sites and companies carrying PCBs are following all the rules. This way we may keep our Canadian wildlife intact.
Questions
Q. Who is paying the bill for this work?
A. The Province through the Department of Transportation and Public Works is currently paying the remediation costs. Environment Canada and the provincial Department of Natural resources contributed to some of the previous activities.
Q. How long will PCBs stay in the soil or sediments if nothing is done to remove them?
A. Natural biodegradation mechanisms for PCBs are not fully understood but current scientic information suggests the PCBs would remain for hundreds of years.
Q. Do animals with PCBs in. their systems pass them on to their young?
A. Mammals can definitely pass PCBs along to their young through milk. It is possible that other pathways exist during pregnancy.
Q. If the sediments were to be dredged, would this kill off most of the contaminated fish anyway, either directly or by removing their food source?
A. If the sediments are dredged in North Bay a certain number of fish right in North Bay itself will be killed because their habitat or food source have been destroyed. However, the majority of the fish in the rest of the lake system won't be affected by the dredging. There will still be fish contaminated with PCBs and there will still be PCBs in the sediments in the rest of Five Island Lake, although at much lower concentrations than are currently found in North Bay.
Q . When if ever will the fish in. the lake chain be safe for consumption again? After the clean up is complete and the life span of the contaminated fish is over, are there any plans to restock the lake?
A. Because there will still be some PCBs in the sediments (dredging North Bay might be able to remove 70 percent of the total PCBs in the lake system) it is likely that some fish will continue to be contaminated for a very long time. Because there is no way to remove all the PCBs from the lake system it makes little sense to restock the area.
The Five Island Lake CLCThe CLC consists of eleven volunteer representatives appointed by local homeowners and ratepayers associations, and representatives of the Departments of Environment and Transportation and Public Works. The co-chairs are John Hoyt (resident) and Gordon Roche (NSDoE).
The mandate of the Committee is to:
- Help the community and the government exchange information and discuss concerns
- Work with government to develop a remediation plan that will be environmentally sound, technically viable and acceptable to the community.