Pesticide Warehouse Fire
Canning, Nova Scotia

In the early morning hours of May 31, 1986, a fire broke out at Maple Leaf Farm Supplies Limited pesticide warehouse situated on Main Street, Canning, Nova Scotia. A large variety and quantity of agricultural products including pesticides, herbicides, fumigants, and fertilizers were stored in the building along with seed grains, seed and table potatoes, propane cylinders and miscellaneous farm machinery.

During firefighting operations, an estimated 1.2 million litres of water was used; much of this contaminated water migrated off site passing over adjacent residential properties, into a farmer's pond and eventually finding its way into the Habitant River via drainage ditches and storm drains.

Vegetation and large numbers of worms were killed in the path of the water, and fish and invertebrates died in a local farmer's pond as well as downstream in the Habitant River. A trench was dug to intercept contaminated runoff and wash water during the cleanup phase; however, this trench was constructed after the bulk of fire fighting water had left the site. Roughly 100,000 litres of water was treated by a membrane filtration process known as reverse osmosis to remove contaminants prior to discharge.

Diagram of main water flow from fire site

Several hours after the fire was discovered, municipal and local fire and police officials began evacuating the village of Canning; residents living closest to the fire site were not permitted to return to their homes for six days. A multidisciplinary emergency response and cleanup effort was immediately initiated.

The Spill Site

Canning is a small rural community of approximately 750 people located in Kings County in the predominantly agricultural Annapolis Valley of Nova Scotia. The village is some 10 kilometers from Kentville, the site of the County offices designated as headquarters for the spill response. Main Street closely parallels the Habitant River which flows 1.5 kilometers to an abateau (water control structure) at its confluence with the Minas Basin.

The Maple Leaf Farm Supplies Limited warehouse was a metal-sided structure on a concrete pad situated on a hill overlooking Main Street. The pesticides were stored in a variety of metal, plastic and paper containers. A large number of propane cylinders and two of gaseous methyl bromide were also present; the contents of the latter were not released during the fire. A nearby retail outlet containing a variety of farm products was undamaged by the fire. The inventory records for the warehouse were kept in this building and were, therefore, not destroyed in the fire.

Response, Containment, and Cleanup Activities

The local volunteer fire service responded to the call at 0200 hours on May 31, 1986; following an assessment of the situation, the fire chief requested and received mutual aid assistance from other volunteer departments. He also contacted Transport Canada's CANUTEC office to obtain information on potential hazards of products suspected to be involved in the fire.

Municipal and Kings County officials were promptly advised and they invoked the County Emergency Response Plan which fortunately had been thoroughly tested only days before the fire. By 0300 hours, an evacuation of local residents by firefighters and the RCM Police was underway. A senior citizens home was situated very close to the fire site. Following the evacuation, access to the entire area was restricted to those involved in responding to the incident.

At 0319 hours, CANUTEC relayed information on the spill to the Canadian Coast Guard Traffic Centre, who in turn informed the Nova Scotia Department of Environment (NSDOE) and Environment Canada (EC), and subsequently other interested agencies. Representatives of environmental agencies were on-scene by 0530 hours, May 31, 1986.

Twenty-three firefighters and police officers and one local resident were treated in hospital for possible exposure to chemical fumes and then released.

As mentioned previously, in excess of 1.2 million litres of water was used to control the fire; much later, foam was also applied; contaminated water left the immediate site passing over adjacent properties. A trench was dug to trap water leaving the immediate fire area.

The NS Fire Marshall's officer and the RCMP initiated an intensive investigation into the cause of the fire since there had been a number of suspicious fires in the Annapolis Valley over the preceeding weeks and months. The Fire Marshall retained control of the site for five days; this did not, however, impede the monitoring and cleanup activities taking place there.

Environmental agencies worked closely with the warehouse owner to develop a detailed and current inventory of products in the building and with product manufacturers to determine the safest and most appropriate containment, neutralization and cleanup procedures.

Response teams from pesticide manufacturers came on-scene both to provide technical advice and to recover identifiable products for disposal or re-use.

Environmental samples were collected by Environment Canada, and several laboratories placed on alert to evaluate samples on a priority basis.

The Fundy Health Unit of the provincial Health Department placed an immediate restriction on the use of the municipal water supply until testing confirmed its safety on June 5th. However, an advisory remained in effect after this date for five private wells in the area. The Health Department also coordinated a blood/urine sampling program (acetylcholinesterase, liver and kidney functions) for response crews and others potentially exposed to chemicals. The results of this extensive testing showed no abnormalities. Milk was collected from local diary herds for pesticide residue analysis and cattle in the immediate area were given blood tests and placed under veterinary observation as a precaution.

Chemical Soup

On June 3, 1986, NSDOE issued a Ministerial Order requiring a thorough cleanup of the site by the polluter. The warehouse owner was unable to fund, on his own, such a large operation. Following the invocation of the Good Samaritan Act by the province, the Canadian Agricultural Chemical Association (now known as the Crop Protection Institute of Canada) agreed on behalf of the industry to fund the cleanup and ultimate disposal of contaminated building debris and the remaining "chemical soup". Environment Canada assisted in the cleanup efforts by providing a mobile reverse osmosis unit to treat contaminated water.

Debris was segregated; uncontaminated building materials were disposed of at the local landfill site while pesticide residues, contaminated debris and used filters from the reverse osmosis process were drummed and disposed of at an approved out-of-the-province hazardous waste facility.

Regular media briefings were conducted throughout the incident and the media were allowed on site in a controlled manner for picture taking opportunities. Meetings were held with affected residents to provide them with detailed information on the nature of the spilled chemicals, possible health and environmental implications, and to give them an opportunity to air any concerns they may have had with respect to the evacuation, response, and cleanup activities.

The evacuation order for residents in the immediate area of the fire was not lifted until the evening of June 6, 1986, following an opportunity for those most directly affected to question environmental and health authorities on their findings.

Treatment of Contaminated Water and Debris

Manufacturers/suppliers with pesticides present in the Maple Leaf Farm Supplies Limited warehouse at the time of the fire (Chipman Chemicals, Union Carbide, Dupont Chemicals, Velsicol Canada, BASF, Ciba-Geigi and Hoechst Canada Inc.) responded rapidly to requests for detailed information and cleanup of their products; they also sent representatives on site to remove identifiable pesticide products for reprocessing and disposal. Two cylinders of the fumigant, methyl bromide, were recovered intact from the site by the supplier. Union Carbide recovered and shipped 13 drums of waste Temik from Canning on June 4, 1986.

Following this stage of the cleanup, a hazardous waste contractor, Sanexen International, was retained to undertake the warehouse site cleanup. The company deployed a 40 ft. tractor trailer as an operations centre for the cleanup. Work crews were outfitted with protective clothing to shield them from pesticide residues as well as from caustic cleaning solutions.

The warehouse structure was dismantled and the building materials along with other large pieces of debris were decontaminated with a fine spray of detergent and weak caustic solution, and temporarily stored in a limed and bermed area adjacent to the fire site.

The company segregated contaminated and uncontaminated debris; all large uncontaminated and decontaminated building materials were disposed of in a local landfill. The location of all items deposited at the landfill site were mapped for future reference.

Broken containers of chemicals and loose chemicals were shovelled into labelled steel drums and sealed. The liquid remaining was contained and either vacuumed into drums or treated with soda ash and soaked up using absorbent clays. This material was also drummed and labelled.

Although cleanup crews were able to finally leave Canning one month after the fire, it was almost a year later in March, 1987, that the remaining waste on site (50 drums of manzate waste, 20 drums of waste from the reverse osmosis unit, 111 drums of waste from the cleanup by Sanexen) was shipped to Ontario for treatment and disposal at an approved secure chemical landfill site. This delay resulted from a shortage of space at the selected disposal site and the need for the company to obtain approval for, and then develop, this new storage capacity.

Roughly 100,000 litres of contaminated runoff water and waste water, generated during site cleanup, collected in a trench dug down slope from the warehouse. This water was periodically pumped into a tanker truck to allow settling of particulates and await treatment and disposal. Removal of water from the trench also aided decontamination and dewatering of the fire site. A reverse osmosis unit (mobile filtering system) belonging to Environment Canada was employed to process the waste water. The unit consists of a feed pump, two 5-25 um pre-filters, a high pressure pump and pressure vessels containing reverse osmosis membranes. This unit was on scene from June 10 to June 29, 1986. In combination with activated carbon filters, the unit effectively removed 99 percent of the pesticide residues. Levels in the water were reduced to below background levels prior to discharge to the Habitant River. Alum was used to enhance suspended solids removal prior to filtering. This flocculation step also tended to significantly reduce the concentration of some pesticides in the supernatant solution prior to further processing; for example, atrazine levels declined from 9000 ppb to 200 ppb.

The original volume of waste water noted above was reduced to roughly 4000 litres of sludge and concentrate, and 400 litres of spent carbon. All of this material was drummed and disposed of with other contaminants out of province.

(excerpts from RESPONSE AND ENVIRONMENTAL MONITORING DURING THE CANNING PESTICIDE WAREHOUSE FIRE; R. Percy, W. Ernst; H. Samant, P. Hennigar, L. Trip, Environment Canada; and F. Potter, Nova Scotia Department of Environment)