https://www.hazmatmag.com/hazmat/ontario-environment-ministry-issues-drafts-order-company-investigate-mercury-contamination/1003275717/#

The Ontario government recently issued a Draft Order for preventative measures to the Domtar paper mill.  The draft Order requires the Paper Mill, located in Dryden Ontario, to study the mercury contamination on its property that was deposited by a previous owner.

History of the Mercury Contamination

The origin of the mercury contamination at the site is from Reed Ltd. that operated a chlor-alkali plant at the Dryden property from 1962 to 1975 the used mercury in a process to generate chlorine and sodium hydroxide to bleach pulp.  During this period of operation sewage and waste water from the site, including the chlor-alkali plant, was discharged to an effluent ditch located parallel to the Wabigoon River.  This effluent ditch also served as a settlement basin.  Effluent discharged through a culvert at the north end directly to the Wabigoon River.

From 1963 to 1970 approximately 10 metric tonnes of mercury were discharged into the Wabigoon River through the effluent ditch.  The quantity of mercury discharged from the plant was reduced by 99 percent by 1970 and operation of the plant was terminated in 1975.

The discharges from the plant affected aquatic life in the Wabigoon and English Rivers.  In 1971 Ontario suspended the commercial fishing licences for walleye, pike and sauger for the Wabigoon and English river systems due to the elevated levels of mercury in fish.

Studies by the federal and provincial governments were conducted in the 1970’s and 1980’s in the Wabigoon River to determine the location and the extent of mercury contamination. A joint federal-provincial report from 1983 titled “Mercury Pollution in the Wabigoon-English River System of Northwestern Ontario, and Possible Remediation Measures” in relation to studies conducted in 1973, 1976 and 1979 by the Ministry, provided that mercury levels in fish in the Wabigoon English River system all the way to the Manitoba border were elevated above the limit of 0.5 ppm set by the Canada Food and Drug Directorate for edible fish marketed in Canada.

Further studies of mercury contamination on the surrounding environment were conducted in the 1980’s, 1990’s, and 2000’s.

In March 2016 a report entitled “Advice on Mercury Remediation Options for the Wabigoon-English River System, Final Report” prepared for Grassy Narrows by Rudd et al. concluded more study was needed to determine if mercury releases were still occurring from the former chlor-alkali facility or if the mercury- contaminated river sediments are moving downstream.

Details of the Order

An Order under section 18 of the Ontario Environmental Protection Act, requires a company or individual to do the following:

(a) prevent or reduce the risk of a discharge of a contaminant into the natural environment from the undertaking or property; or

(b) prevent, decrease or eliminate an adverse effect that may result from

(i) the discharge of a contaminant from the undertaking, or

(ii) the presence or discharge of a contaminant in, on or under the property.

The proposed requirements in the draft order issued to Domtar by the Ontario Ministry of the Environment and Climate Change include:

• The development and implementation of a work plan to assess groundwater and soil on the mill site, and surface water and sediment within the Wabigoon River adjacent to the site for the purposes of determining if mercury is discharging from the site to the Wabigoon River.
  • The assessment must include the installation and sampling of monitoring wells along the shoreline and a geophysical survey of the shoreline area. Samples will be analysed for total mercury, methyl mercury and chloride.
• The provision of opportunities for area First Nation communities and other affected members of the public to be engaged in the development and implementation of the work plan, including making the progress reports and final report readily available to First Nations and members of the public who may be affected by a discharge of mercury from the site.
• Upon the completion of the assessment, Domtar Inc. is required to provide a final report to the ministry detailing whether mercury is coming from the land portion of the mill site, or present in sediments within the Wabigoon River portion of the site, and whether mercury has the potential to impact downstream water and sediment quality, and mercury concentrations in fish. Recommendations for further investigation and any necessary remedial measures necessary are also required.
• The order includes timelines to ensure work is conducted in a timely manner.

Domtar Inc. conducted sampling from groundwater monitoring wells on the mill site and provided analysis in December 2016.  The results indicated an elevated level of mercury in one groundwater monitoring well. All other wells were within provincial standards.

Accordingly, the work required by the order is necessary and implements a science-based approach to determine if there is an ongoing source of mercury from the mill property with the potential to impact the Wabigoon River.

If there is evidence that the Dryden mill site is an ongoing source of mercury, then measures to prevent further mercury from entering the river, and how those measures are to be implemented, will be assessed. This may include future orders.