Anatomy of a spill

A provincial court has ruled that negligent management and improper maintenance procedures caused a spill of contaminated uranium mine water at Rabbit Lake, Sask., on Nov. 6 and 7, 1989. During a period of more than 16 hours, about two million litres of untreated mine water escaped from the 9.6-km pipeline joining the Collins Bay B zone pit to the mill. For more than 10 hours, the spill overflowed emergency catchment basins.

An estimated one-half of this volume entered Wollaston Lake, the source of drinking water for Wollaston Post residents. The lake supports commercial fishing, hunting and trapping.

Sampling conducted in mid-November by the Saskatchewan Research Council detected no increase in uranium, radium 226 or other radionuclides accumulated by fish in Wollaston Lake. The council recommended further sampling when fish resumed feeding in spring, 1990. This study would investigate possible delayed bio-accumulation of radionuclides through the aquatic food chain. Peter Courtney ofSEPSstated in June that this recommendation would instead be carried out by Cameco during the summer.

The spill was spotted as a stain on snow and ice by Robert Phillips, Cameco’s superintendent of environmental protection, while flying into the minesite with Robert Maloney, an inspector for the Atomic Energy Control Board (AECB). As recounted by George Jack, manager of the AECB’s waste management division, the mine water escaped when a frozen cast iron gate valve cracked at a small valve house near the midpoint of the pipeline. The electric power was off because a broken electrical transformer had not been repaired. Therefore, the electrical heater in the house, which was supposed to prevent the valve from freezing, was not working and neither was the exterior floodlight. A back-up transportable power generator was available at the mill, but inexplicably was not employed on the night of the spill.

When the pipeline was installed in 1984, Cameco incorporated a remote monitoring system designed to reveal spill conditions. This computerized alarm system was documented in Cameco’s licensing submissions to the AECB and to SEPS . However, software problems developed and Cameco, without informing, in writing, the AECB or SEPS , decided not to use the system. “Our staff was stretched thin, and we failed to discover and rectify this omission,” says Jack.

Instead, Cameco was relying on visual inspection of the pipeline and on manual processing in the mill control room of flow information transmitted from meters on the pipeline. As it turned out, neither visual inspection nor metering was satisfactory.

The meters revealed significant drops in pipeline pressure and volume, and thus might have alerted control room staff to the spill. However, they were inadequately trained and supervised to reach this conclusion. Cameco had also assigned staff to patrol the pipeline by driving in shifts along the haul road running parallel to the line. Although patrollers passed the culprit valve house every two hours, they failed to see the spill. The house is hidden from the road by an earthbank and, according to Jack, patrol crews did not leave their truck.

The AECB initiated charges against Cameco under the Atomic Energy Control Act of 1946. These charges included operation of the Rabbit Lake waste management system without the approved control systems and failure to provide competent waste water supervision. This was a case of “sheer, blatant culpability,” says Jack.

Cameco pleaded guilty to these charges, paid the maximum fine of C$10,000 on two counts and then the mine manager was let go.

Acting independently on recommendation of SEPS, the Saskatchewan Justice Dept. moved to sue Cameco for the environmental discharge of contaminants leading to the “reasonable possibility” of water pollution, under Clause 17 (a) of Saskatchewan’s Environmental Management and Protection Act. The maximum fine is C$1 million.

Cameco challenged the Environmental Management and Protection Act on constitutional grounds, but was unsuccessful. The company then entered a plea of not guilty, and the trial was scheduled for late August.

This story has a happy outcome, however. A breach in the same pipeline in January, 1990, released 90,000 litres of B-zone mine water into a ditch designed to contain pipeline leakage. The AECB did not consider prosecution for this leak, which was caused by a tear in the weld of a heavy-gauge polyethylene pipe flange. The main point, says Jack, is that the automated alarm system installed by Cameco after the November spill functioned properly, the staff response was correct, and the leak was contained.