Esterhazy, Saskatchewan
(1985-1986) and (2004 – 2009)
(Client: Mosaic - 2009, IMC- 1985-86)
One of the most amazing grout curtains ever installed was the grout curtain through dolomitic limestone around the K2 Shaft (Esterhazy, Saskatchewan). The vertical grout curtain was installed from a donut shaped tunnel around the shaft at a depth of 2,760 feet below surface.
During 1985, ECO designed the remedial grouting program order to obtain a residual hydraulic conductivity of 0.01 Lugeon. A continuous, 265 foot high, grout curtain was created from the underground tunnel which straddled 4 distinctive aquifers under very high hydrostatic pressures (400 to 1200 psi). The hydrostatic conductivity in the “worst” aquifer, the upper DB4, was between 200-700 Lugeon; the Souris River formation: 10-40 Lugeon; the lower DB4: 60-100 Lugeon and the DB3: 10-35 Lugeon. The hydraulic conductivity in all aquifers was governed by intercrystalline porosity; therefore suspension grout could not be used. It was noted during the pre-excavation grouting for the shaft sinking in the sixties that acrylamide readily flocculated in contact with brine and a spread of only 2 feet was obtained. ECO formulated an acrylamide solution grout that did not flocculate in contact with brine and enabled a grout spread in excess of 10 feet (after acid stimulation of the formation) to create a continuous single row grout curtain of overlapping grout cylinders (tested via verification holes) under extreme pressure and flow conditions. During the 1986, 66% of the grout curtain was completed, at which point the seepage into the shaft was reduced by 90%.
During 2007 & 2008, ECO designed and provided the site engineering for the completion of the remaining 34% of the curtain. The execution of the remainder of this grout curtain was completed in the summer of 2009.