Amendment to PSA - Engineering Design Services for St. Joseph Riverbank Stabilization - Cardno, Inc.

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Project Understanding & General Project Approach Cardno completed the feasibility study for this project in June of 2019. The feasibility study expanded the project from the initial area of concern along Riverside Drive at the intersection of Yukon, to other related issues including the erosion upstream on the east side of the river along North Shore Drive downstream of Iroquois Street, and the potential cause of erosion at both sites; which is an artificial bar extending downstream from the stormwater outfall at the junction of Leland Avenue and Riverside Drive (Figure 1). The embankments are eroding along the river because the thalweg of the river is undercutting the steep slopes. The design approach will be to examine the artificial bar in more detail and determine if, in fact, it is contributing to the realignment of the river and thus causing the erosion of the toe of slope on either one or both areas identified (Figure 2). If that is the case, we will work with permitting agencies to see how the bar can be manipulated to direct the thalweg back toward the center of the channel. This would prevent a continuation of the downstream movement of the eroding banks. Both of the existing eroded embankments will require armoring at the toe of slope to stabilize the banks that have sloughed into the river. As much as possible, our designs will feature restoration of the slope with native vegetation above the waterline. The native vegetation will include tree planting. The purpose of the Engineering Design Project will be to prepare physical design plans and specifications that will be ready to bid out for construction and to ensure a successful overall project through communication with the City of South Bend, permitting agencies and affected landowners. earth 2000 meters, 800 Figure 1: Location of three sites to be addressed for design