How would the Chalk River Mound leak? Let us count some of the ways

Canadian Nuclear Laboratories (CNL) – run by a consortium of profit-making multinational companies – is proposing to build a giant mound that it misleadingly calls a “Near Surface Disposal Facility” for a million cubic meters of radioactive waste at its Chalk River facility along the Ottawa River.

CNL’s high cost ad campaign (paid for with Canadian tax dollars) says the dump is safe and uses “proven technology”. Ads say the dump will protect the public and the environment.

However, CNL’s draft environmental impact statement (EIS) describes several ways that contents of the proposed “engineered containment mound” of radioactive waste could leak into the Ottawa River. Here are some of the ways:

During operation (while the dump is being filled)…

1. Wastes being added to the mound would be exposed to the elements. 

Rain and melting snow would leach radioactive contents down through the mound. The liquid would be collected and pumped uphill to a water treatment plant. Some but not all radioactive contaminants would be removed prior to releasing the treated leachate into wetlands that drain into the Ottawa River. (Table 3.5.3-1 on page 3-23 of the draft EIS) 

2. Radioactive water (tritium) would leach in very large amounts from the mound. 

Tritium is part of the water molecule and cannot be removed by water treatment. The draft EIS suggests the very high tritium content will be reduced but does not say how. Untreated tritium would be discharged to wetlands that drain into the Ottawa River where it would get incorporated into fish and enter drinking water supplies Large quantities of tritium would also be released from the dump as water vapour. 

3. Other toxic substances such as PCBs leaching from the mound would be only partially removed by water treatment.. 

Table 3.5.3-2 on page 3-25 shows that treatment would only partly remove non-radioactive toxic compounds in the wastes such as lead, PCBs and dioxin. Measurable amounts would be released to the environment. 

4. Heavy storm events would erode the mound’s surface and wash toxic substances into low areas. 

Highly contaminated water washing off active dumping areas would be pumped to the water treatment plant. Less contaminated water would be pumped to three storm-water management ponds around the perimeter of the facility and be discharged to adjacent wetlands. Ponds would provide only “basic” containment of sediments before their contents were released (draft EIS explains this on page 3-57) 

5. The capacity of storm-water ponds would be exceeded during extreme rainfall events or snowmelts. 

The draft EIS (page 9-2) says that pond overflow “would be conveyed by inlet and emergency outlet structures adjacent to the surface water management ponds,” presumably to be released directly into adjacent wetlands. 

6. Other possible ways the facility might leak during operations (not described in detail the EIS) include tornado damage, pump failures during extreme storm events with loss of electrical power, improper installation of the base liners, puncture of the base liners by heavy or sharp materials, melting of liners by radioactively hot materials, and blockage of the leachate collection system. 

After closure…

1. Wastes in the mound would be re-exposed to the elements when the top cover fails. 

After waste dumping ended the leachate collection system and water treatment plant would be shut down, and a top cover placed over the wastes. The draft EIS acknowledges that the top cover would fail with “normal evolution” through forces such as erosion, extreme storms, burrowing animals, root penetration, etc. 

2. Failure of the top cover while the base liners remain intact would initiate the “bathtub scenario”. 

Rain and melting snow would again leach the radioactive wastes, 

but the leachate collection and pumping system would no longer be operational. Contaminated leachate would be trapped by the bottom liner and accumulate in the space between the mound and the surrounding berm. Leachate levels would rise and spill over along the low point of the 

berm. 

Long-lived radioactive elements such as plutonium and uranium, exposed to wind and water erosion, would flow into the river for thousands to millions of years. Eventual failure of the bottom liners would also allow radionuclides to move into groundwater. The Ottawa River would be permanently contaminated by radioactive wastes. Countless generations of people drinking its water would be exposed to increased cancer risks.

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