Rehabilitation of Site No. 1 at the Eustis Mining Complex
(Municipalité du Canton de Hatley)
Rehabilitation work was carried out at the former Eustis 1 mining site in 2007 and 2008 at a cost of $2.6 million. The Eustis site is among the contaminated sites under the responsibility of the Gouvernement du Québec.
The work consisted of covering the mine tailings with a waterproof barrier to prevent oxidation, rainwater infiltration, and subsequent acid mine drainage.
The rehabilitation was authorized by Ministère du Développement durable, de l’Environnement et des Parcs and carried out in close cooperation with Municipalité du canton de Hatley and Fondation des villages miniers Capelton, which owns the land.
Mining in the Estrie region dates back to the 19th century, when exploration in 1840 led to the discovery of a number of copper and pyrite deposits. The region’s first mines opened in 1850. However, it wasn’t until 1860 that copper mining really took off, when demand for the metal skyrocketed due to the American Civil War (1861–1865).
Copper mining was concentrated mainly in Ascot County, where the Capelton and Eustis mines were located. The Capelton industrial and mining complex operated from 1865 to 1939. The Eustis mine was known in turn as the Lower Canada (1865), Hartford (1866-1872), Crown (1872-1888), and Eustis (1888-1939) mine. With a depth of 2,260 meters, for many years it was the deepest copper mine in Canada.
Underground mining was first carried out in the Hartford shaft at Eustis 3, the oldest of the sites. The ore extracted there was sorted by hand at the site before being transported to the Eustis 1 site for roasting. Starting in 1879, the ore was extracted from the mine through a drift that connected to the Hartford shaft. The barren rock extracted during the shaft sinking and the manual sorting operations was dumped along the banks of Ruisseau Eustis (now known as the Eustis 2 site). The mine closed down in 1939.
Location of the Eustis Site
The Eustis mining site is located approximately 9 kilometers south of Sherbrooke, in Municipalité du canton de Hatley. It consists of three sites, including a tailings site (Eustis 1) and two waste rock piles (Eustis 2 and 3). The Eustis mine tailings are a source of acid mine drainage. The total surface area of these three sites is approximately 15 hectares.
The approximately 11 hectare Eustis 1 site is located on Chemin Stafford, bordering Rivière Massawippi. The site is divided into three zones: The old railroad that has been converted into a bike path connecting Municipalité de North Hatley and Lennoxville bisects the Eustis 1 site (sections A and B), while Chemin Stafford divides the Eustis 1A site from a small waste rock pile known as the experimental cell. The tailings storage area is a mound about 20 meters high and is just a few meters upstream from the bike path and east of Chemin Stafford (Eustis 1A).
The spillage zone extends from the bike path to Rivière Massawippi over about 300 meters in length (Eustis 1B). The site also includes an experimental cell to the west of Chemin Stafford that was restored in the mid-1990s.
Eustis 1 Site and its Components
The 1.5 hectare Eustis 2 site containing barren rock is about 700 meters north of Route 108, alongside Ruisseau Eustis.
Eustis 2 Site
The 3 hectare Eustis 3 site containing barren rock is located on a slope alongside Ruisseau Eustis, just over one kilometer north of the Eustis 2 site.
Eustis 3 Site
Ruisseau Eustis runs into Rivière Massawippi.
Problems Stemming From Acid Mine Drainage1
Environmental problems at this site are nothing new. In the early days of mining here, the sulfur contained in the ore was eliminated by roasting the ore on a bed of hot coal, which would burn for about 70 days as the sulfur oxidized. The roasting process released sulfur emissions that affected the surrounding environment and had a harmful effect on livestock and human health. In the early 1880s, this process was replaced by a flotation concentrate plant.
More than 70 years after mining operations were abandoned, the presence of sulfurous tailings is the main problem at the Eustis mine site. The acid mine drainage caused by the oxidation of iron sulfide mineral in the mine tailings is a major source of contamination of Ruisseau Eustis and Rivière Massawippi.
In 1983 samples taken by Ministère de l’Environnement revealed that the water in Ruisseau Eustis was extremely acidic, with a pH of 2.3. In 2003 Berryman2 detected concentrations of cadmium, copper, iron, lead, and zinc in Ruisseau Eustis that were respectively 41; 2,490; 67; 25; and 65 times higher than criteria for the protection of aquatic life. As for Rivière Massawippi, it is contaminated by both the Eustis 1 site and the high levels of heavy metals in Ruisseau Eustis.
Rehabilitation of the Eustis 1 Site
In the early 1990s, work was done on the experimental cell to cover the mine tailings with a waterproof layer of de-inking residues in order to limit leaching. Due to the instability of the slope and the odor emanating from the residues, corrective measures are required.
In November 2006 Ministère des Ressources naturelles et de la Faune undertook rehabilitation work at the Eustis 1 site. The proposed rehabilitation was based on the findings of the site characterization. Construction plans and specifications were drawn up and an invitation to tender was issued.
The Eustis 1 site rehabilitation, which began in 2007 and was completed in November 2008, included the following:
During the rehabilitation work, Chemin Stafford had to be closed temporarily to ensure the safety of motorists and allow off-road vehicles to access the site. A temporary detour was also created next to the flood plain (Eustis 1B) to redirect cyclists during work along the bike path.
Before and after views of the Eustis 1A cell upstream from the bike path
In foreground, view of the flood plain (Eustis 1B) and, in background, of the Eustis 1A site
Rehabilitation of the Eustis 2 and 3 Sites
Following characterization of the sites, rehabilitation plans for these two sites were developed. They include containing barren rock under a waterproof barrier consisting of a geomembrane covered by a layer of soil and vegetation. Ditches will be dug upstream from the two sites in order to collect and direct surface water into Ruisseau Eustis.
Work is slated to begin in June 2009 and will be complete by November 2009 at the latest.
|1.||Caractérisation environnementale des sites miniers Eustis 2 et 3, Final report presented to Jacques Langlois, Fondation du village minier de Capelton, by Université de Sherbrooke and Les consultants SM Inc., September 2001.|
|2.||BERRYMAN, David, ST-ONGE, Jacques, GENDRON, Andrée, BROCHU, Charles : L’impact d’anciens parcs à résidus miniers sur la qualité de l’eau et les communautés benthiques de la rivière Massawippi et des ruisseaux Eustis et Capel , Ministère de l’Environnement, 2003.|