Comments on the McArthur River Proposal

(last updated 11 Apr 1997)


Comments on Environmental Impact Statement for the McArthur River Proposal


Prepared for the
Saskatchewan Uranium Coalition
Marvin Resnikoff, Kim Knowlton, and Kal Island

Radioactive Waste Management Associates

March 1, 1996

(reproduced here with permission)

Radioactive Waste Management Associates
526 W. 26th Street Rm.517, New York, NY 10001, USA
Tel. +1-212-620-0526, Fax: +1-212-620-0518, E-Mail:

> For figures and references, please contact Radioactive Waste Management Associates.


Uranium mining activity in Northern Saskatchewan has increased rapidly over the past several years (see figure 1). Mines already exist at Rabbit Lake, Key Lake, and Cluff Lake. Operations have been approved at the McClean Lake Project site. Two proposals have been submitted by Cogema Resources, Inc. and the Cigar Lake Mining Corporation for mining at the Midwest and Cigar Lake sites, respectively. Most recently, an Environmental Impact Statement (EIS) for the proposed McArthur River Project was released in October 1995. The McArthur River Project EIS, compiled by Cameco, details planned operations and impacts at two sites. First, very high-grade uranium ore would be mined at the McArthur River site, near Read Lake. The ore would then be transported by truck about 80 km southwest to the Key Lake mill site. There, after being processed to extract uranium, McArthur River ore tailings would be blended with lower-grade `special wastes' derived from ores mined at Key Lake. The McArthur River tailings would be disposed of at Key Lake, within the former open-pit mine known as the Deilmann pit (or Deilmann Tailings Management Facility) (see figure 2).

Ground water will tend to flow into both the McArthur River and Key Lake mines. This water will have to be pumped out, and some of it will be used for mining operations. Each site will have a water treatment plant for remaining liquid wastes, and treated effluent will be discharged into local watersheds. Mining will also produce large volumes of waste rock, some of which will be replaced in the mines or pits, and some which may remain in above-ground piles adjacent to the pits and nearby lakes. There is an above-ground tailings management facility (TMF) already at Key Lake, about 3 km southwest of the present mill site. The Gaertner pit, a second open-pit mine at Key Lake similar to the Deilmann, has also been dewatered. The above-ground tailings facility holds tailings and wastes from all the processing of Key Lake ores to date.

According to the EIS, following uranium extraction at the Key Lake mill, the McArthur River tailings will be piped 4 km east to the Deilmann pit. The tailings will be deposited using two different methods. One, the `pervious surround' method, is in use at Rabbit Lake. It attempts to reduce ground water flow through the tailings, and thereby reduce the amount of radioactive and metal contamination that could enter the local groundwater. A more permeable lining layer of crushed rock and sands is placed in the pit around the tailings. This permits ground water to flow around, rather than through the tailings. The filter envelope is then drained of all contaminated ground water via sumps, dewatering shafts, and wells. Ideally, by the time of decommissioning, contaminated porewater will have already been released from the tailings during their consolidation and pumped away. Tailings produced from milling Key Lake ores will be deposited `subaerially' (above water and exposed to the elements) into the Deilmann pit until 1998, using this `pervious surround' method.

The other method involves underwater or `subaqueous' tailings deposition. Around October 1998, Cameco will switch to a subaqueous method, in order to minimize radioactive exposures from the high-grade McArthur River ores that will be milled by then. The subaqueous method attempts to deal with major amounts of ground water inflow by depositing tailings from a barge, through a pipeline, and into a flooded pit. The EIS states that, `Below water disposal into a flooded pit is attractive because the ground water gradient across the pit and through the tailings is minimal.' This method also reduces dust, radon gas and gamma exposures. A deep pond will be maintained above the Deilmann tailings, and some of the pond water will be pumped out and treated to keep local ground water moving in toward the pit. The subaerial method allows for evaporation and gravity drainage to assist somewhat in consolidation, but consolidation is much more effective with the subaqueous method. Worker exposures are typically higher during subaerial deposition. Other problems with the method include frost, dust, radon and gamma exposures and leaching of metals into groundwater.

The Deilmann pit disposal facility will be much larger than many other northern Saskatchewan projects. Its pit capacity will be 35 million m3 total, compared to 4.8 million m3 capacity for the JEB pit at McClean Lake. The excavated hole at Deilmann will be 150 m deep, compared to JEB's 100 m. There will be 110 dewatering wells around Deilmann pit, compared to 29 around the JEB pit. Large amounts of ground water will flow through the overburden sands and toward the Deilmann pit, and the McArthur River ore tailings will be extremely radioactive. Therefore, ground water will eventually be allowed to flow into the pit, leaving a relatively deep layer of pond water over the Deilmann tailings, even after decommissioning.

As part of the initial mining and subaerial tailings deposition at Deilmann pit, a huge dewatering project will totally drain some local lakes and streams, and create a cone of depression at least 2.5 km wide. Under Cameco's plan, `clean' water pumped from both Deilmann and Gaertner pits will be discharged southeastward into nearby Horsefly Lake, at an estimated rate of 10.2 million m3/yr. `Dirty' waste water from milling and mining processes, along with radioactively contaminated ground water, will be treated and then discharged westward into Wolf Lake at an estimated rate of 1.8 million m3/yr. Together, 12 million cubic metres annually will be discharged into the local surface waters.

Radioactive pore water which escapes from the McArthur tailings `paste' will be pumped from the underdrain below the tailings, to promote their consolidation and capture escaping radioactivity. The tailings themselves are supposed to become so dense that they are less permeable than the surrounding rock, preventing ground water from flowing through them and carrying away contamination. After milling ceases, decommissioning of the Deilmann pit will involve installing a layer of sandy materials on top of the tailings, and perhaps dumping in more waste rock to further enhance consolidation. Large volumes of high-nickel waste rock, special wastes, and radioactively- contaminated surface facilities will be placed into the Gaertner pit during decommissioning. Pond water will remain above the wastes buried within both Deilmann and Gaertner pits.

These mining and disposal operations will have a major effect on the area's environment. The mines, mill, and pit will produce large amounts of wastewater, and even after treatment this water will contaminate the lakes into which it is discharged. Waste rock will be a source of nickel, arsenic, radium and radon contamination, and radon will emanate from the mill and the tailings facility as well. As mentioned, pumping associated with the pits will lower the water table enough to lower or completely dry up several nearby lakes; plants and animals in fragile wetlands will die. Finally, over the long term, the pits will remain a source of ground water contamination. All of these problems add to the cumulative impacts of the region's many other uranium mining operations. In this report, we detail the environmental effects that must be weighed in considering whether to approve the proposed mining operations. We also identify a number of unresolved issues which Cameco should address.

Most of these issues involve the Deilmann pit. After decommissioning, a considerable depth of pond water will remain above the tailings mass. This is intended to reduce radioactive exposures from the high-grade uranium ore tailings. However, it is not clear that all of the material intended for the pit will fit inside and still maintain an adequate water cover depth. Also, assertions that the tailings will be effectively isolated from the ground water may prove overly optimistic. Although half of the porewater escaping from the tailings is supposed to be captured in the pit's underdrain pump, porewater could also escape sideways, contaminating the ground water and the water pumped from the perimeter wells, which would then have to be treated. In addition, if pumping from the underdrain is impaired, the amount of water pumped from the pond above the tailings may have to increase. These problems would require that the mill's water treatment plant be enlarged, but contingency plans do not estimate the volumes that would need to be treated.

Ground water monitoring might not continue beyond 3 years after the pit's closure. There appear to be no contingency plans for remediation in case of excessive ground water contamination. All the radium from the ore will be concentrated in the treatment plant sludges, and these are to go into Deilmann pit. However, some water treatment will continue after the pit is closed, and the disposal site for these sludges has not been mentioned. Estimates of the amount of radium leaching from the tailings may not be conservative. We are also concerned that radon emanation may have been underestimated; that ice could interfere with water treatment and effluent discharge; and that the possible effects of large forest fires on disposal operations have not been discussed.

Similar to the Midwest Joint Venture EIS, there are several environmental health and safety issues that are unanswered or incompletely described in Cameco's EIS. Because of the similarities between the planned mining and tailings waste disposal operations at the two sites (both make at least some use of the `pervious surround' method), many of the same issues are relevant to the two. Below is a list of issues pertinent to the proposed McArthur River/Key Lake Project.


Geology and hydrology

The rich uranium ore deposits of northern Saskatchewan are associated with a geological structure known as the Athabasca Basin. The McArthur and Key Lake ore bodies are located in the southeastern portion of the basin. About 1.8 billion years ago, metamorphic rocks of the Canadian Shield (here called the Wollaston Domain) were eroded into a surface known as an unconformity. Sandy sediments were later deposited on top of this unconformity, then consolidated into the relatively flat lying unmetamorphosed sandstones of the Athabasca Group. Uranium has since been mobilized and redeposited around the unconformity, especially along fault zones. At McArthur River, the ore body is associated with an area of faulted rock 500 to 600 meters below the ground surface (BGS).

Overlying the basement rocks and the Athabasca sandstones are glacial deposits such as drumlins, with axes that trend northeast to southwest, paralleling the glacial movements. Large lakes formed by melt water during the glaciers' retreat deposited silt and sand as outwash plains across the area. Most ground water flows through the glacial overburden sands. The ground water flow that does occur in the Athabasca sandstones is mainly along fracture systems. Much of the fracturing has occurred in more brittle, silicified areas of altered sandstone. Surface drainage is generally to the northeast in the region.

Mining operations

If approved, uranium production from McArthur ores could begin in 1999. Cameco would operate the McArthur River Project on behalf of a joint venture among three mining companies, and Cameco compiled the EIS. Cameco also operates Key Lake and Rabbit Lake, presently the world's two largest high-uranium mines. Ore reserves at McArthur River are estimated to be 416 million pounds, with an average grade of 15% U3O8. This is an extremely high-grade ore; the ores found at Key Lake, for instance, are an average of only 2% U3O8. Some of the McArthur ores are as high as 50% U3O8. In fact, the McArthur ore will be blended with special waste rock from Key Lake, just to bring down its uranium content to an average blended grade of 4% U3O8 and reduce worker exposures. Mining operations are already underway at Key Lake, where the Gaertner orebody mining began in 1975 and the Deilmann open pit mine began in 1976. It is estimated that 182 million pounds of ore will be taken from Key Lake through 1999, when its reserves will be gone. Production at McArthur River is expected to begin in 1999, and last for at least 20 years, through 2019.

At the McArthur River site, Cameco will pump out or freeze inflowing ground water, and then use the `raisebore' mining method to extract uranium ores. This involves drilling a hole from an upper chamber down through the ore body to a lower chamber, then pulling a reaming head up through the uranium zone. The ore will be crushed underground and ground into a slurry, then pumped to the surface. There the slurry will be thickened to a paste that will be put into containers and transported by truck 80 km southwest to the Key Lake mill. An average of 8 roundtrips a day will be made, each truck will carry 4 containers, and each container will hold 5.5 tonnes of ore.

Mining operations at McArthur River will generate 1.12 million tonnes of waste rock. There will be two waste rock pads: one for mineralized rock (water from here will go to the treatment plant) and a non-mineralized pile (will be used for construction of roads). Some of the mineralized waste rock will go back into the underground mine workings (as preferential backfill), and the rest will be sent to the Deilmann pit. The sludges from the water treatment plant, which will contain high levels of radium, will be filter pressed, stored temporarily in the mineralized waste storage area, and eventually either disposed of underground as shaft backfill or be sent to the Deilmann pit (see figure 3).

Worker exposures

The EIS estimates that occupational exposures at McArthur River will be below the proposed occupational dose limit of 20 mSv/yr. Cameco's estimate for total radon emissions coming out of the McArthur mine shaft is 7.0 x 106 Bq/sec. The largest total dose would be received by a worker grouting drifts in the McArthur mine, whose total dose would be 11.39 mSv/yr. This is 57% of the proposed worker dose limit of 20 mSv/yr.

Surface water impacts

Release of McArthur River effluent to Read Creek

The McArthur River minewater will first be sent to a surge pond, then be treated (peak capacity of 4,800 m3/day) , held within 3 monitoring ponds, and finally discharged to Boomerang Lake, about 1.5 km from the mine site. From there flow will continue to Lucy Lake, Read Creek, May Creek, Little Yallowega Lake, and Yallowega Lake (see figure 4). It will eventually reach Waterbury Lake, Waterfound Bay, Black Lake, Fond du Lac, Lake Athabasca and the Beaufort Sea. 1.7 million m3/yr will be discharged, making a total of 34 million cubic meters over the mine's estimated 20-year lifetime.

The ore that will be mined at McArthur River, besides being extremely rich in uranium, is high in nickel and arsenic. The treatment plant is intended to remove about 98% of the radium- 226, and about half of the nickel, arsenic and other heavy metals from the wastewater. But Cameco's predictions show that arsenic levels in the receiving waters may exceed the Saskatchewan Surface Water Quality Objectives (SSWQOs). The SSWQOs are intended to protect aquatic life, and are 0.11 Bq/L for Ra-226, 0.025 mg/L for nickel, and 0.05 mg/L for arsenic. The estimates of maximum effluent concentrations are 0.37 Bq/L Ra-226, and 0.15 mg/L each for nickel and arsenic. These three estimates exceed the SSWQOs.

Boomerang Lake, which is less than 1 m deep, is so shallow that it will essentially be made up entirely of this effluent. Furthermore, it is not clear that these effluent concentration estimates account for 20 years' worth of impacts from McArthur River ore production (through the year 2019). The EIS should predict cumulative water and sediment impacts for the small initial receiving water bodies like Boomerang Lake, instead of larger lakes like Lucy Lake, which are farther downstream and will dilute the effluent effects. Furthermore, Read Creek freezes over in winter and there could be problems with the McArthur effluent flooding a wide area around the stream.

Key Lake Mill and Deilmann Tailings Pit

Geology and hydrology

The Key Lake area is about 70 km east-southeast of Cree Lake, in north-central Saskatchewan. In the immediate area of Deilmann pit, there are three major rock horizons, similar to those found at McArthur River. The lowest is the gneissic basement rock, whose lowest top elevation is around 432 masl. Above that are the Athabasca sandstones, (whose lowest top elevation is 476 masl), and above that are the loose overburden (glacial outwash) sands. The pit is located within a bedrock depression known as the Key Lake trough or syncline. This trough is up to 1,400 m wide, with a flat bottom 600 m below the bedrock surface (about 100 mbsl). Mineralization at Key Lake is within the syncline, at the intersection of the unconformity and a shear zone, a situation similar to McArthur River.

The natural ground water table is relatively shallow, and numerous lakes cover the region. The pre-mining water table within the overburden was approximately 0 to 15 m deep in the glacial outwash sands, and from 0-30 m deep in the glacial till. The general direction of ground water flow in the bedrock is from southwest to northeast, and from west to east within the overburden. The EIS states that the loose overburden aquifer (comprised of outwash boulders and sands) contains 99% of the ground water flow across the pit. Locally, large amounts of water flow through fracture systems within the sandstones. Fractures are commonly associated with local faults, which trend both east-west and north-south. Most of the open fractures are in the north wall of Deilmann pit.

Milling and tailings disposal

Expansion of the already-existing Key Lake mill from 14 million to 18 million pounds/year will accommodate the additional McArthur ores, and their milling will last 20 years until 2019. Deilmann, a former open pit mine, should be fully excavated by the end of 1996. The final pit will be about 1300 m long, 600 m wide and up to 170 m deep. The Deilmann pit was once the southern part of Key Lake, before Cameco's mine dewatering project began. This previous dewatering was accomplished through a combination of ground water pumping and surface water diversion via canals and ditches. Cameco plans to continue depositing the remaining Key Lake ore tailings to an elevation of 412 masl within the Deilmann Pit Tailings Management Facility (Deilmann pit). Above this level, beginning in approximately 1999, McArthur tailings will be disposed of as a paste under subaqueous conditions. The paste tailings from the Key Lake mill will be piped 4 km east to the pit, within a concrete pipe trench with sumps and monitors.

The pit tailings disposal is to start with a `pervious surround' method similar to the one that has been used at Rabbit Lake since 1985. About 110 wells within and surrounding the Deilmann pit are to pump out inflowing ground water, thus dewatering the pit for disposal operations. Crushed rock and sand are to be put into the bottom and part way up the sidewalls of the pit as a lining `envelope.' Porewater from the tailings will seep to the bottom of the pit, then be collected and pumped up to the mill for treatment. It is estimated that 50% of the porewater will remain locked up within the tailings, and that the other 50% will be extracted and sent to the mill for use as process make-up water. Pumping of the porewater from the underdrain, along with the additional weight of overlying tailings, will consolidate the tailings into a lower-permeability mass. `Like the system at Rabbit Lake, ground water flowing towards the tailings in the Deilmann TMF will take the path of least resistance, traveling in the envelope and around, not through, the compacted tailings.' This is the essence of the `pervious surround' method.

It is expected that as time progresses, dewatering volumes will decrease as water levels are restored in the pits. Later on, during the underwater or subaqueous disposal of McArthur River tailings, ground water pumping will be discontinued, allowing water to flow back into the pit and form a pond. `Blended' McArthur River tailings will subsequently be disposed of underwater into the flooded pit. The depth of overlying pond water will start at approximately 93 m, then get shallower (to about 34 m) as the tailings depth builds up.

There is a second pit, the Gaertner pit, also in use at Key Lake. It, too, is a former open-pit uranium mine. Thirty-one dewatering wells are located on its southern and eastern sides only, about 100 m apart, to intercept water flowing into the pit. Similar to Deilmann pit, the Gaertner pit occupies what was once a lake (the northern part of Seahorse Lake). The effluent from dewatering these two pits will be treated by reverse osmosis (to remove Ni, Ra-226, U, Zn, Cu, Pb, and As), and then discharged to Horsefly Lake. `Dirty' (highly radioactive) effluent will be returned to the Key Lake mill for use as process make-up water, before being discharged to Wolf Lake (see figure 5).

Waste rock volumes

80 million tonnes of waste rock will be at Key Lake in the huge Deilmann North, Deilmann South, and Gaertner waste piles. Another 1.2 million m3 of `high-nickel basement material' or `oxidized special waste' was excavated during mining of the Deilmann ore body. This appears to be the same TMF material that could create 4.5 million m3 in proposed tailings from Ni/Co recovery. Of this high-Ni material, 1/3 will go back into the Deilmann pit (perhaps at the bottom, as a base for the drain materials), and 2/3 will be hauled to nearby Gaertner pit, `where it will be covered with a clean cap. When all of the high Ni rock has been placed in the bottom (elevation 470 to 480 masl) of the Gaertner pit, the water level ... will be allowed to rise to approximately 2 m above the final clean cap rock (about 502 masl).' Approximately 2 million tonnes (1.2 million m3) of `special waste' from Key Lake ores will be piled next to the two pits, and is to be blended into the very high-grade McArthur River ores in order to reduce worker exposures.

Water table depression

The impacts of the Deilmann pit on local hydrology were not discussed in EIS Section 5, and they should be. Huge amounts of ground water will be pumped from perimeter wells to `dewater' the pit, causing a large cone of depression, or area where groundwater flows in toward the tailings disposal facility at Deilmann. This is intended to prevent contamination from escaping the pit, and to maintain the desired pondwater depth. Dewatering has already been used to facilitate uranium mining at Key Lake. The average volume of ground water removed from 1982 to 1993 was 11.8 million cubic metres per year. The resulting `zone of influence' was 14 km long, and covered 30 km2. The natural water table has been lowered by 50 metres or more, and the ground water capture zone extends 4 km from the pit. The end result has been the complete draining of four local lakes, the removal of 70-98% of the water from 4 other lakes, and diminished flow in four local streams. Cameco's EIS does not estimate how big the Deilmann pit cone of depression could become, stating only that annual monitoring of ground water levels around the pit will be done, and maps will be drawn accordingly. Without a detailed estimate of the number of lakes and streams that will be affected, Cameco cannot predict what the environmental impacts of the Deilmann pit will be.

Surface water impacts

Wolf Lake

At the Key Lake mill, uranium extraction process waste waters will be bulk neutralized, then undergo barium chloride treatment to precipitate radium. The resulting overflow will be held in monitoring ponds and sampled for radioactivity, heavy metals, and other contaminants. Any `dirty' waste water that does not meet effluent standards will be sent back to holding reservoir 2, and then recycled to the mill. In the past, about 30% of the treated mill effluent has been thus recycled back to the milling process. If instead the monitoring pond water is within regulatory effluent limits, it will be released to the environment at Wolf Lake, at an estimated rate of 1.8 million m3/yr.

The receiving water bodies will be, sequentially: Wolf Lake, Wolf Creek, Fox Lake, Yak Creek, David Creek, Unknown Lake, David Creek again (a segment known as `Pyrite Creek'), Delta Lake, and David Creek (see figure 6). All the lakes immediately downstream of the effluent discharge are relatively shallow, and are of below-average depth for the Key Lake area. Receiving huge volumes of effluent will have a relatively greater effect on the aquatic ecology of these shallow bodies. Wolf Lake, in fact, is the shallowest lake in the area (less than 1.5 metres), and has a total volume of only 50,000 m3. This means that a volume of radioactive effluent 36 times the lake's total volume will be flushed into it each year.

Cameco estimates that their effluent already constitutes 30 - 90% of the flow in the larger streams. The EIS should consider the impacts on the smaller lakes and creeks that will be the first to receive the effluent volumes. Wolf and Horsefly Lakes have already `had significant alterations to their habitat - both of these small lakes are composed largely of effluent.' The EIS estimates for contaminant loading of nickel, arsenic, and radium-226 from Key Lake effluents indicates that the SSWQO for nickel (0.025 mg/L) will be exceeded by a factor of 7 (about 0.17 mg/L). The EIS should be sure to assess the total impacts from 20 years' worth of McArthur River tailings disposal, since the EIS often includes only operations through the year 2013. David, Delta, Fox and Wolf Lakes, as well as Yak and Wolf Creeks, contain spawning grounds for fish species, and these could be destroyed by the long-term influx of Key Lake effluent.

Horsefly Lake

A second discharge stream, this one into nearby Horsefly Lake, will be comprised of water from dewatering the pit area. Typically these dewatering effluent volumes are 5.5 times greater than the discharges into Wolf Lake from mill wastewater treatment, which was described above. Ground water pumped from both Deilmann and Gaertner pits will be monitored for radioactive contamination. If `clean,' it will be discharged southeastward into Horsefly Lake. Estimates are that about 40- 50% of the pit dewatering water will be clean enough to be directly discharged, but the remaining water is to be sent to a reverse osmosis (RO) plant for treatment. The RO plant is being constructed primarily to reduce the nickel in the dewatering discharge at Horsefly Lake. In 1988, nickel levels in Horsefly Lake increased dramatically, most of it coming from the Gaertner dewatering effluent. The RO plant is an attempt to deal with these high Ni levels, and is also intended to reduce concentrations of Ra-226, U, Zn, Cu, Pb and As in the Horsefly Lake discharge.

It is estimated that the RO plant will handle 10,000 m3/day. Cameco's plan is that about 15% of the RO product water will be recycled to milling operations, and 85% (the `clean' product water) will be discharged to Horsefly Lake. The resulting discharge to Horsefly Lake will equal 24,000 m3/day (10.2 million m3/yr) which includes the `clean' reverse osmosis treated water and any clean water from the Deilmann and Gaertner dewatering wells.

However, the success of reverse osmosis in treating uranium mine and mill effluent and reducing nickel concentrations is not strongly supported in the EIS. Section 2.6.15 of the Main Document notes that in 1995 the reverse osmosis plant was being constructed, but gives no evidence of its actual efficiency in removing nickel. A `separate study' is considering other possible mechanical, chemical and biological treatment methods for removing excess nickel from dewatering water, such as introducing algae into the pond water to bioremediate high Ni levels. Another possible plan is to use ion exchange. The results of all these studies should be part of the EIS. In other uranium mining sites, reverse osmosis has not been successful in removing radionuclides and metals from waste waters. At uranium in-situ mines near Bruni, in southern Texas, RO units were to be used to remove radioactive and chemical contamination from waste waters before they were discharged into the environment. However, the RO units experienced serious problems with equipment failure and poor membrane efficiency. The reduced efficiency resulted in a decreased ratio of `clean' to `dirty' water, and the process had to be abandoned.

Nickel levels in dewatering discharges to Horsefly Lake in 1995 were 0.3 mg/L. This is over 10 times greater than the SSWQO of 0.025 mg/L. The EIS alleges that the RO plant `will reduce nickel levels, currently about 0.3 mg/L, to less than 0.08 mg/L,' but provides no data to back up their claim. Alternative proposals for dealing with nickel contamination in Key Lake effluent discharges and the ground water around Deilmann pit should be discussed and supported by Cameco in much greater detail within the EIS.

The water bodies receiving the dewatering discharges will be: Horsefly Lake, Little McDonald Lake, McDonald Lake, McDonald Creek, Wilson Lake, Outlet Creek, and the Wheeler River. Similar to Wolf Lake, the enormous volume of dewatering flow to be discharged into these lakes and creeks could have significant impacts. The contaminant loading to the environment from dewatering discharges in 1992 was 1,768 kg/year of nickel, 18 kg/year of arsenic, 823 kg/year of uranium, and 724 MBq/year of Ra-226. The resulting concentration of nickel was 0.144 mg/L, almost six times greater than the SSWQO for nickel. Cameco's EIS has predicted contaminant concentrations in surface water bodies after 10,000 years, but must estimate the shorter-term values, which will be far higher.

Moreover, many of the calculations to estimate the amount of radioactivity that will enter the environment do not clearly include the contribution from a full 20 years' worth of McArthur River tailings. Many of Cameco's estimates use data from the `base case' in which only Key Lake tailings are being disposed. Even their `expansion case' often only deals with McArthur tailings disposal to the year 2013. However, the EIS states that it will take at least 20 years for McArthur production to end, thus the `hot' tailings will last through the year 2019. Cameco should verify that all of their loading estimates for radioactivity and heavy metals that would come from the Key Lake mill and Deilmann pit include at least 20 years' worth of McArthur River tailings, and thus are truly protective of human health and the environment.


Many of the metals associated with milling uranium tend to accumulate in the sediments of the effluent receiving waters. As early as 1992, arsenic, nickel and uranium in sediment samples collected downstream of the Key Lake mill effluent outfall `were found at elevated levels.' At Wolf Lake, arsenic levels as high as 650 ppm (mg/g), or almost 200 times background, have been found. As a reference, the background arsenic levels just upstream in David Lake and David Creek are 3.3 to 6.8 ppm. Uranium in Wolf Lake sediments has been measured at 91.5 ppm, which is over 60 times the David creek background value of 1.5 ppm.

Horsefly Lake sediments also have elevated values for nickel, due to co-precipitation with iron hydroxides in the dewatering discharge. The EIS concedes that, `Clearly, discharges at Key Lake have affected sediment quality within the mixing zones for each discharge.' The long-term effect of dietary uptake of contaminants from sediments is often greater than the impacts from direct uptake from water. The entire aquatic foodchain could be affected, as well as humans who eat local fish. Because of these sediment effects, establishing baseline values, site-specific sediment/water distribution coefficients, and ongoing monitoring of sediments is essential, especially for U, As, Cd, Pb, Ni, and Zn. The EIS should discuss cumulative effects of 20 years' worth of McArthur tailings disposal and associated effluent discharges on local sediment quality.

Ground water contamination

The proposed switch from subaerial to subaqueous tailings deposition has several purposes. First, it is timed to coincide with the introduction of the more radioactive McArthur River tailings into the pit. The layer of water that is to be maintained above the tailings will help reduce worker exposures. Second, the subaqueous method, which will include pumping of porewater from the underdrain, is intended to promote consolidation and decrease permeability in the tailings, just as the tailings mass is coming into contact with the more permeable sandstones.

Several advantages of this plan are mentioned in the EIS. The choice of a partial rather than full side/underdrain will leave more space in the pit, and will require less material to be removed from local borrow pits, hence less environmental impacts will occur. The plan will decrease the decommissioning time, since the ground water table will already be nearly re- established during operations. Pump-and-treat removal of ground water contamination will already be underway during the entire subaqueous phase. This will decrease the duration of remediation necessary during pit decommissioning. Allowing the surrounding groundwater to flow in toward the pit will save pumping and treating additional volumes of dewatering effluent, reducing environmental effluent impacts. Other advantages of underwater deposition include fewer problems with dust, radon and gamma exposures, and frost disruption.

However, once the level of tailings deposition is high enough to intersect the fractured sandstone horizons, it will be harder to keep escaping porewater from flowing sideways into the country rock. Without the dewatering wells operating around the pit, the natural groundwater flow paths will be re-established, and radioactive contamination will move away from the pit and to the northeast. At Rabbit Lake, where subaqueous tailings disposal has been underway since 1986, `the overall horizontal permeability is probably some 2 to 4 times higher than the vertical' and could be up to 10 times higher. Besides lateral migration along fractures associated with local faults, porewater could also contaminate the overlying pond water to a high degree. The porewater at Deilmann will contain 62 to 150 Bq/L of Ra-226, up to 0.288 mg/L of Ni, and 14.8 mg/L of arsenic. Cameco's modeling predicts that the porewater will eventually move into the overlying pond water. Ra-226 will exceed the SSWQO of 0.11 Bq/L for the first 12 years of pump- and-treat from Deilmann pond. Within 200 years, Ra-226 levels in Deilmann Pond could be back up to 0.12 Bq/L, and remain that high for 10,000 years. The pond water will affect both the ground water and possibly surface water bodies, since perpetual care to prevent its escape is unrealistic.

The pondwater will also be extremely high in nickel, containing up to 0.5 mg/L (which is twenty times the SSWQO of 0.025 mg/L) `over several years' as a result of 1,600 kg/yr of nickel leaching from surrounding waste rock. Nickel will leach from the surface waste rock piled around the two pits, and also from waste rock submerged in Deilmann pit. A plume of nickel- contaminated water is expected to enter the ground water around Deilmann Pond, and move about 1.5 km east within just 10 years after decommissioning. Plumes of radium-226 and arsenic will likewise migrate east and northeast from Deilmann, but at slower rates. These contaminant travel times, along with ground water loading calculations, could be underestimates if McArthur tailings to at least the year 2019 have not been included.

Pit volume

If consolidation of the tailings paste is less than expected, the pit capacity may be too small. Studies of similar methods used at Rabbit Lake have found that there can be a considerable margin of error in modeling consolidation for the partial drain design. The materials that may go into Deilmann pit include:

The plans are now for all 15 million m3 of Deilmann pit capacity to be occupied as follows :

Material                        Estimated           Estimated
                                 volume              finished
                                occupied           top elevation
Key Lake tailings + partial       2 million          412 masl
under/side drain materials          cubic meters
(to the year 2000)

McArthur River tailings           4.5               ~449 masl
(to 2013; consolidated volume)

Proposed tailings of Ni/Co        4.5               ~462.5 masl
recovery from segregated
high-nickel waste rock

`Future McArthur reserves'        4.0                476 masl, elev. of
(2013-2019+)                                       lowest top of sandstone
TOTAL:                           15 million cubic meters

It appears that Cameco is trying to fit just enough wastes into Deilmann to cover the top of the sandstone, but not exceed it. The idea would be to not have their wastes contacting the glacial overburden materials, which `conduct 99% of the groundwater flow.' Because there are many variables involved -- degree of tailings consolidation, volume of inflowing ground water, actual volumes of waste generated, and actual fate of those wastes - this will be difficult to insure. For instance, Cameco has mentioned extracting Ni and Co from `segregated high- nickel waste rock.' If that's feasible, they will put the resulting tailings into Deilmann pit. But Cameco has no check on their estimates of the tailings volume that this process would create. The EIS should discuss their contingency plans in case `the pit won't fit.'

It is estimated that there will be another 10 million m3 of space left in the pit above the top of the tailings and the lip of the pit. Presumably this will be filled by `Deilmann Pond' water to an elevation of 510 masl. That would make for an average 34 m pond water depth over the tailings. This `extra' 10 million m3 may be very important in accommodating what's left of the 2 million tonnes (1.2 million m3) of `special waste' which may go into the Deilmann pit without blending/milling; 800,000 m3 of leftover high-nickel waste; and the huge amounts of waste rock (80 million tonnes) leftover from the excavation of Gaertner and Deilmann pits. These volumes are not specifically included in the 15 million m3 pit capacity estimate, and should be discussed. The EIS states, `...flushing of oxidized products from the existing waste rock piles around the Deilmann pit is expected over a period of 10-20 years with increasing concentrations in the ground water beginning to develop by the year 2001.' If waste rock, high-nickel segregated waste and unmilled special wastes are all to be put into Deilmann pit and then flooded with water, extremely high concentrations of Ni, As, Cd, U and other metals will be released into the local groundwater and into the overlying pond water. But this is only held out as a `possible' future option. The ground water impacts of this contingency should be modeled in this EIS.


Decommissioning plans are to be ironed out in detail at a future time, according to the EIS. General plans are laid out, however. At McArthur River, decommissioning would begin at earliest about 20 years after production begins (about mid- 2019). All surface facilities will be removed, and the site will be re-contoured and re-vegetated. Remaining waste rock will be returned underground, and environmental monitoring will continue for 3 years. At Key Lake, the existing, aboveground tailings pile deposited west of the mill (the `TMF') from 1983 - 1995 is to be covered, contoured and re-vegetated. The TMF has had dust and frost problems, hence the change to pervious surround/subaqueous methods at Deilmann pit for the future. At Deilmann pit, the submerged tailings will be capped with a minimum 2 m thickness of glacial till (sand). The weight of the cap will `increase consolidation, and Cameco may dump more rock in to add even more weight.

Ground water will be allowed to rise to its `pre-development level,' and any water below the tailings will be pumped and `treated until it reaches acceptable water quality standards.' The waste rock piles next to the two pits may be contoured, capped and re-vegetated `if necessary.' Another alternative would be to dump the waste rock into the pits. At Gaertner, 2/3 of the high-nickel basement material will be dumped into the pit, `where it will be covered with a clean cap. When all of the high-nickel rock has been placed in the bottom (elevation 470 to 480 masl) of the Gaertner pit, the water level ... will be allowed to rise to approximately 2 m above the final clean cap rock (about 502 masl).' Regional groundwater levels will recover to approximately 518 masl, which is about 1 m above the original Key Lake level, within 15-20 years following decommissioning.

After decommissioning, the former Seahorse Lake (adjacent to Gaertner pit) and Key Lake (adjacent to Deilmann pit) will be changed forever. Both former, natural lakesites will be partially infilled with tailings and waste rock. At Deilmann, this will leave only `Remnant Key Lake' (the northernmost portion of the original Key Lake), Deilmann North and South waste rock piles, and `Deilmann Pond' in between, a pond with the Deilmann pit beneath. At Gaertner, only the southern parts of Seahorse Lake will exist, and `Gaertner Pond' will take up its northern arm. The decommissioning plans as presented are quite confusing. The EIS should provide a map of which areas will remain as water bodies versus natural or newly created land areas. All of Cameco's plans for operation and decommissioning are designed to stay within a proposed public dose limit of 1 mSv/yr (equal to 100 mrem/yr).


The radium-rich sludges from the McArthur River and Key Lake treatment plants will end up in Deilmann pit. But at decommissioning time, after the pit has been `closed,' where will the sludges from post-pit closure treatment of drain water be sent? The EIS should discuss the fate of these sludges, since pumping and treatment of pond water may continue for several years after decommissioning.


Uranium mining operations affect air quality through particulate emissions during milling, especially during yellowcake drying operations, and through radon emissions from waste rock and tailings. According to the EIS, 3.3 x 106 Bq/sec of radon will be emitted from McArthur River operations, and annual radon concentrations will increase by over 50 Bq/m3 at Key Lake. An area 40 km long will have increased radon concentrations as a result of Key Lake operations. A 1979 Key Lake EIS estimated that the total radon release rate from the Key Lake mill, open pits, ore storage, and tailings would be 3.6 x 107 Bq/sec. More recent calculations use a source term of 3.8 x 108 Bq/sec. Radon levels observed at Key Lake from 1986-1993 were highest in summer (0.289 Bq/L) and were 0.4 Bq/L right over the tailings.

If we divide Cameco's estimated 3.8 x 108 Bq/sec of radon by the area of Deilmann Pond (580,000 m2), one gets an estimate of 655 Bq/m2/sec. Dividing this by a factor of 25, to account for reduced radon emissions through the pondwater cover, one gets 26.2 Bq/m2/sec emanating from Deilmann pit. This is less than the value RWMA calculated for radon emission from the JEB pit at McClean Lake, which will use a similar subaqueous method. The smaller emission rate is due to the effect of `blending' the very hot McArthur River ores with Key Lake materials, bringing the Ra-226 concentrations of the tailings down to 325 Bq/g. Without blending, Ra-226 can be up to 1350 Bq/g. If in the future blending does not occur, or if the tailings do not remain underwater, radon emissions could increase dramatically.


Cumulative aquatic impacts

Although McArthur and Key are located within two different watersheds, their effluent could have cumulative regional impacts downstream, where drainage systems meet. Key Lake effluent is discharged into Wolf Lake, and dewatering flows move through Horsefly Lake into McDonald Lake. Both eventually flow to the Wheeler River, Russell Lake, the Geikie River and into Wollaston Lake. Most (70%) of Wollaston Lake drains east and into Hudson Bay, but 30% moves westward into the Beaufort Sea system. Thus around Waterfound Bay, cumulative impacts from some of the Key Lake effluents will combine with the effects of McArthur River effluent, which moves entirely toward the Beaufort Sea. Appendix 5C discusses the cumulative impacts of McArthur and Key Lake, along with the four other Saskatchewan uranium mines: McClean Lake, Rabbit Lake, Midwest, and Cigar Lake. Although the EIS concludes that cumulative regional impacts will be `minimal,' the EIS should clarify that its assessment is truly based on the possible `worst-case' emissions from the six Saskatchewan uranium sites.

Air emissions

Air emissions can also have a cumulative effect. Radon and the radioactive particles into which it decays are concentrated locally, but they do become distributed in the Northern Hemisphere atmosphere. There they add to the background dose of radiation affecting everyone's health. The Key Lake disposal operations will have the largest radon emissions of all of the uranium projects in northern Saskatchewan, over two times higher than either Rabbit or McClean Lake.

The possibility of nickel-cobalt recovery from the `segregated high-nickel waste rock' has not been adequately discussed in the EIS. There should be another complete EIS done for any proposed recovery processes, since they can have devastating environmental impacts. For instance, the nickel smelter at Sudbury, Ontario is the largest source of acid rain in North America, due to its enormous sulphur emissions.

Cumulative ground water impacts

Section 5 of the EIS, `Discussion of Cumulative Impacts,' does not mention the long-term effects of Deilmann pit and escaping contamination on the local and regional ground water. This most likely will be one of the major impacts of the entire project, and Cameco should consider this as a critical cumulative effect.

Ice & permafrost

Ice will form in the winter within the Deilmann pond over the tailings. Tailings will be deposited from a fixed central barge location during this time. But potential problems exist with ice buildup in lines, the settling and monitoring ponds, and Deilmann pond. Ice will tend to form on the pond further away from the barge deposition point. During winters when there is less snow cover, ice will also tend to form more. When ice melts in the spring/summer, there will be large radon releases. While Cameco considers ice a major environmental concern, they provide little data on how the depths or extent of ice will affect operations. The effects of ice on surface water discharge and tailings disposal operations should be evaluated. Ice buildup on very shallow lakes like Wolf Lake, which will receive effluent discharges, could create huge pools of effluent on top of the ice. There should be a discussion of these impacts.

Forest fire

In 1981 a huge forest fire (the Close Lake Fire) burned the entire McArthur River area. In 1978, a large fire occurred at Key Lake. According to Cameco, there are hundreds of forest fires throughout Saskatchewan annually. Yet there is no discussion of contingency plans to reduce the possible impacts of large fires upon operations at McArthur and Key Lake, particularly during disposal operations at Deilmann pit. These should be part of the EIS.


There is no doubt that the proposed McArthur mine site, Key Lake mill and Deilmann tailings disposal pit will contaminate the environment. The McArthur River ores in particular contain high-grade uranium but are also rich in other radionuclides and heavy metals, which will become important contaminants. Large amounts of wastewater will be generated which, even after treatment, will contaminate local shallow lakes. Wolf and Horsefly Lakes are already composed mostly of mill and dewatering effluent, and their sediments are concentrating arsenic, nickel, and uranium. The water in Deilmann Pond will receive radioactive porewater from the tailings below, and if any untreated pond water escapes from the pit, it will endanger surrounding surface waters.

Uranium milling will release particulates into the air, and radon will emanate from the waste rock and tailings. Huge piles of waste rock may be left on the ground surface, and decommissioning plans are not yet described in adequate detail. Because of heavy metals leaching out of this waste rock, arsenic levels could exceed regulatory limits soon after operations begin. Several local lakes and streams will be lowered or drained dry as ground water is pumped from around the Deilmann pit.

The uranium ores contain large amounts of radium-226, which will be concentrated throughout milling and disposal operations and will ultimately be sent to the Deilmann pit. Since radium-226 is especially mobile in surface water and ground water, the migration of radium-226 away from the tailings pit is of particular concern. Contamination from the tailings pit will eventually escape and enter the local ground water system. With the operators of the several proposed or operating uranium sites each relying on downstream dilution to dissipate the effects of their particular operation on local surface water, ground water and air, the cumulative effect of regional mining activities is another important concern. All of these environmental impacts must be weighed in deciding whether to approve the McArthur River/Key Lake proposal.

In addition, we have identified a number of unresolved issues, particularly with regard to plans for the Deilmann tailings pit. The following issues should be addressed before any decision is made to allow the proposed operations to begin.

Comments by the Saskatchewan Uranium Coalition on the
Report of the Joint Federal-Provincial Panel on Uranium Mining Developments in Northern Saskatchewan
McArthur River Uranium Mine Project

April 7, 1997

The Saskatchewan Uranium Coalition and our technical consultants, Radioactive Waste Management Associates, based in New York City, have been involved in all aspects of the Federal- Provincial proceedings concerned with the proposed McArthur River Uranium Mine Project. We provided comments on the original EIS and supplements and focused our attention on the proposed disposal of uranium mill tailings in the Deilmann Pit at Key Lake and long-term monitoring of the decommissioned tailings pit.

The Joint Federal-Provincial Panel, chaired by Dr. Donald Lee, allowed us ample opportunities to express our views and to raise questions. Many of their comments regarding tailings disposal and long-term monitoring, reflect our concerns and go some direction in alleviating our concerns. We would like here to underline some aspects of the Panel's recommendations that are important to implement and also to express our fear that some of the Panel's recommendations do not go far enough.

The Federal and Provincial governments should understand that the McArthur ore body is quite rich in uranium ore, one of the largest finds in the world. It is estimated to contain 416 million pounds of yellowcake at an extremely rich average grade of 15%. In the process of milling this uranium ore, approximately 85% of the original radioactivity in the ore will remain and be placed in the Deilmann Pit. From 550 metres below the surface, these tailings will be brought to the earth's surface and placed in the Deilmann Pit where they will remain radioactive and hazardous for several hundreds of thousands of years. This is the impossible challenge: to set up mechanisms that will protect many future generations from harm.

The Joint Federal-Provincial Panel recognizes the problem by stating that "the only way in which the people of the region can be assured of environmental protection is to monitor the facility is not possible to guarantee a walk-away, zero-risk tailings storage facility." In recognition of this fact, the Panel recommended the establishment of a Uranium Mining Contingency Fund to cover the costs of long-term monitoring and maintenance and the potential implementation of contingencies. We strongly support the establishment of such a fund. These wastes will far outlive the corporations that generated these wastes. The corporations should therefore contribute to an external fund that is overseen by the Federal-Provincial government.

At issue are important questions concerning the size of the fund and the governance mechanisms, including the establishment of criteria for maintenance and repair. In our comments to the Panel, we raised concerns about the need to pump and treat contaminated water from the sidewells near the Deilmann Pit. A contingency fund should include funding for means of remediating groundwater contamination. Any treatment implies that contaminated materials would be returned to the Deilmann Pit. This could be a never ending process. As we pointed out in our comments on the McArthur River Project EIS Addendum,

Issue #6: Contingency plans are needed in case local ground water contamination or Deilmann pond contamination exceeds estimated levels. This should include a worst-case estimate of the volumes of water requiring treatment, water treatment expansion, the effects on ground water wells, cost estimates, and how the companies of the joint venture will prepare to meet these costs. We are concerned that contingency plans may be abandoned if costs are high.
Response: The Addendum states that if concentrations of contaminants in Deilmann Pond come close to or exceed the Saskatchewan Surface Water Quality Objectives (SSWQOs) during operations, two options are available: (1) try to reduce the tailings porewater concentrations by washing and rethickening the underflow from counter-current decantation of the tailings, or (2) increase the thickness of the cover materials over the tailings from 2 metres to 4 metres, using sand/silt or waste rock.1 But there are no contingency plans given in case groundwater contamination exceeds predicted levels in the future, especially after decommissioning.

In our comments we also raised questions regarding the frequency of monitoring. The Panel has not come to grips with this issue as well, leaving it to the licensingprocess to decide. We fear that the licensing process, generally shielded from public view, will lead to an ineffective monitoring schedule.

Issue #8: Decommissioning plans should be clearer, especially regarding the fate of the enormous waste rock piles next to Deilmann and Gaertner pits. The EIS should provide a map of which areas will remain as water bodies versus natural or newly created land areas. Post-decommissioning monitoring should be frequent enough to allow an effective response in case of unexpected amounts of tailings settlement, ground water flow, pond or ground water contamination, or radon emissions.
Response: The Addendum does not provide a clear description or map of the projected shape/area of lakes that will remain during and after Key Lake pumping/disposal operations. The frequency of post-decommissioning monitoring is still unspecified. Cameco states the cycle over which regulators will assess whether decommissioning criteria are being attained is "to be determined."2 Monitoring and data review must be done frequently enough to allow for early detection and effective response to escaping contamination, but there is no assurance of this in Cameco's updated plan.

Finally, we are concerned about the action criteria for remediation efforts. Above what uranium and hazardous chemical concentrations, will the AECB require Cogema to take action?

1 McArthur River Project EIS Addendum, McArthur River Joint Venture p.2.4.41.
2 Ibid., Fig.

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