ENG-TECH Consulting Limited (ENG-TECH) completed the slope stability assessment for the placement of limestone rip-rap along the shoreline for erosion protection along your properties. ENG-TECH understands all seven (7) properties owners are interested in participating in a group effort to limit erosion. The purpose of the assessment was to assess the existing riverbank stability and provide recommendations for shoreline erosion protection that will not have a negative impact on existing slope stability.
The analyses were completed to assess the stability of the existing bank and determine the impact shoreline erosion protection will have on overall riverbank stability. Historical records were reviewed to estimate soil shear strength parameter values and the depth to various soil layers. This method of analysis is satisfactory in showing the percent changes in the factor of safety (FS) of potential slip surfaces (PSSs) pre and post the placement of rip-rap. A percent increase in the FS of PSSs shows the placement of rip-rap will not have a negative impact on existing riverbank stability.
The use of limestone rip-rap to minimize shoreline erosion is the most viable option. The rip-rap can be placed starting at elevation +/- 226.5 m, and extend into the river channel to elevation 221.5 m. The rip-rap alone would have a slight positive impact on riverbank stability, although its intended use is for shoreline erosion protection. Approximately 7850 tonnes of limestone rip-rap will be required. The placement of rip-rap has no negative impact on riverbank stability, and furthermore a slight positive impact on the FS of the PSSs shown from the analyses. As such, the rip-rap is designed to limit erosion while not having a negative impact on existing riverbank stability.