Some of the bedrock shelf upstream of the intake will be removed to promote water flow into the new powerhouse. This will be done through blasting and hoe ramming.
Weirs will be removed in preparation for the installation of the new ones.
The time it takes to complete the blasting will depend on how the rock behaves. Current estimations predict approximately 2 months.
The same monitoring procedures from Step 1 remain in place. Principally, the monitoring of water clarity upstream, downstream and in the work area and the maintenance and adjustment of sediment and erosion control measures and equipment.
In addition, monitoring will be completed by the blasting company. This will include monitoring for vibration and overpressure of nearby structure and overpressure on the Mississippi River.
As in Step 1, there is a potential for turbidity.
Blasting could result in fish kills or property damage.
The blasting plan developed for this site took into account the potential to harm any nearby structures and also follows the mitigation measures created by the Department of Fisheries and Oceans for the protection of fish during blasting in or near water.